Diagnosis

The diagnosis of pulmonary hypertension is established primarily by echocardiography, which provides the definitive diagnosis of any underlying structural heart defects, and, in most cases estimates of the pulmonary artery pressure (PAP), the right atrial pressure, any tricuspid or pulmonary regurgitation, and evaluation of RV function. Presence of ventricular septal bowing into the LV during late systole to early diastole is an indicator of pulmonary hypertension.⁹⁶⁷ The echocardiogram guides the patient care team to identify the new development of pulmonary hypertension, and RV status, and enables close ongoing monitoring of the response to therapeutic interventions. Echocardiography quickly identifies if pulmonary hypertension develops in conditions not typically at risk for exacerbation of pulmonary hypertension, such as a post cardiac catheterization newborn following intervention for aortic valve stenosis or a child with postoperative elective atrial septal defect repair.

All of the information related to the pulmonary vascular hemodynamics is obtained through direct measurements made during cardiac catheterization to determine severity and reversibility of the pulmonary hypertension and, thus, potential for surgical intervention for the underlying defect.³²¹ Such assessment is performed prior to cardiac transplantation to minimize the risk of RV dysfunction post transplant³²¹ (see Chapter 17). It may also be performed for patients undergoing the Glenn or Fontan procedures for single ventricle circulation, because they require low pulmonary vascular resistance for optimal postoperative cardiac output and recovery.³²¹ Even mild elevations in PVR may result in severe impairment of cardiac output in Fontan circulation.⁷¹⁷

As noted above, in addition to baseline hemodynamics, the reversibility or reactivity of the pulmonary vascular resistance to vasodilator drugs can be evaluated during cardiac catheterization. Administration of 100% oxygen, inhaled nitric oxide, intravenous prostacyclin or adenosine should produce pulmonary vasodilation,⁶³⁸ indicating a “reactive” pulmonary vascular bed. Pulmonary vasodilation should be associated with increased pulmonary blood flow, decreased pulmonary artery pressure and increased cardiac output. A decrease in mean PAP by 10   mm Hg to reach a mean PAP < 40   mm Hg with a normal or high cardiac output is defined as a response to vasodilator therapy.⁶³⁷ The lowest achievable PVR can be identified. Patients may respond to pulmonary vasodilator therapies without a return to normal pulmonary vascular resistance, and therefore will be identified with elevated perioperative risk for residual pulmonary hypertension,³²¹ so appropriate anticipatory care can be planned.

Failure to respond to administration of pulmonary vasodilators identifies irreversible pulmonary arterial damage and is termed a “fixed” pulmonary vascular bed with inoperable congenital heart disease. This is Eisenmenger syndrome, and usually corresponds to a pulmonary vascular resistance above 12 Wood units.⁶¹³

The patient with pulmonary hypertension requires careful observation and support following cardiac catheterization to avoid hypoventilation and other causes of alveolar hypoxia, acidosis or any other factors that may contribute to further pulmonary vasoconstriction.^638,804 Patients with suprasystemic PAP before noncardiac surgery or cardiac catheterization were found to have significant risk of major perioperative complications, including pulmonary hypertensive crisis and cardiac arrest.¹⁴⁰ Common factors promoting pulmonary vasodilation will need to be supported, with avoidance of the clinical situations that cause further pulmonary vasoconstriction. (See section, Management of Pulmonary Hypertension).

Evaluation of actual histologic (structural) changes in pulmonary arteries requires a biopsy, which may be accomplished through a thoracotomy or thoracocscopy.⁷¹⁷ However, these biopsies are rarely performed⁶¹³ and are associated with a 30% in-hospital mortality.⁴⁰⁸

Clinical Signs

Despite optimal care, patients with pulmonary hypertension can experience exacerbations that can lead to hemodynamic instability, and, if not successfully treated, can be fatal. Anticipation and early detection is crucial to management and avoidance of progression. An acute pulmonary hypertensive event can be triggered by pulmonary vasoconstriction with resultant rise in pulmonary vascular resistance and pressures. The right ventricle is stressed but may not immediately fail, and systemic arterial blood pressure is stable initially. Signs and symptoms of a pulmonary hypertensive event include an acute rise of pulmonary artery pressure. Clinical signs can include tachycardia, and signs of poor perfusion, but a stable arterial blood pressure. Acute increases in afterload, such as reactive pulmonary vasoconstriction, are poorly tolerated during the neonatal period,⁹³⁵ and are poorly tolerated by a dysfunctional postoperative RV, so may rapidly progress to a hypertensive crisis. (See Table 8-18.)

A pulmonary hypertensive event can quickly deteriorate to a pulmonary hypertensive “crisis.” These crises seem to be associated with severe pulmonary vasoconstriction, an acute rise in right ventricular afterload, right ventricular failure, decreased left ventricular filling and sudden deterioration in cardiac output and systemic perfusion with a sudden fall in arterial pressure. Most of the “crises” occur with weaning of mechanical ventilation⁷¹⁷ or suctioning, but they can occur at any time. The pulmonary artery systolic pressure rises to or exceeds systemic pressure. The signs of a pulmonary hypertensive event versus crisis are summarized in Table 8-18. Once these events develop, they often cluster and must be avoided by promoting factors that produce pulmonary vasodilation and avoiding conditions that contribute to pulmonary vasoconstriction. Rapid recognition of a pulmonary hypertensive event is critical to avoid deterioration to a crisis. A crisis left untreated quickly progresses to cardiovascular collapse, arrest, and death.

Table 8-18 Clinical Signs and Symptoms of Pulmonary Hypertension Events and Crises

From Nieves J, Kohr L: Nursing considerations in the care of patients with pulmonary hypertension. Pediatr Crit Care Med 11(2 Suppl):S74-S78, 2010.

Clinical signs of RV failure in the patient with pulmonary hypertension can include tachycardia, a loud pulmonic component of the second heart sound, palpable right ventricular heave, hepatomegaly, ascites, peripheral edema, and signs of inadequate perfusion. Patients older than 1 year of age may demonstrate elevated jugular venous pressure. A holosystolic blowing murmur of tricuspid regurgitation can be heard over the lower left sternal border.⁹⁶⁷ Signs of inadequate cardiac output will quickly produce a metabolic acidosis, drop in mixed venous oxygen saturation, and a rise in serum lactate (greater than 2.2   mmol/L). For further information, see Chapter 6 and the Postoperative Care section in this chapter (and Table 8-35 later in this chapter).

Prevention

Neonates, infants, and children with many forms of heart disease are at risk for developing elevated pulmonary vascular resistance. Since it is difficult to predict if or when pulmonary hypertension will develop, surgical correction is scheduled to eliminate the possibility. Medical management of congenital heart patients at risk for developing pulmonary hypertension includes close monitoring of status to optimize the timing for interventions in each child. Almost all congenital heart lesions corrected in a timely manner have resolution of the pulmonary hypertensive structural changes with a return of normal hemodynamics.⁷¹⁷ Lesions such as atrioventricular septal defect, large patent ductus arteriosus, and truncus arteriosus are typically repaired during the first months of life to prevent permanent pulmonary hypertension and optimize the potential for controllable pulmonary vascular resistance perioperatively. Critical pulmonary hypertensive conditions in the newborn are emergencies and are treated immediately after birth (i.e., obstructed total anomalous pulmonary venous return or hypoplastic left heart syndrome with intact atrial septum).⁵¹⁴

Children undergoing single ventricle staged palliations require low pulmonary vascular resistance for survival.^926,935 Moderate increases in PVR or PAP can lead to critical alterations or failure of Fontan or Glenn circulations. In two-ventricle circulations, elevated pulmonary vascular resistance increases right ventricular afterload and work, forcing the right ventricle to generate higher pressure to maintain normal cardiac output through the pulmonary vascular bed.

In the postoperative period if right ventricular (myocardial) dysfunction is present (particularly in the presence of a right ventriculotomy), an increase in pulmonary vascular resistance can trigger progressive right ventricular failure and low cardiac output. Children with right ventricular dysfunction, particularly postoperative newborns with a right ventriculotomy following repair of tetralogy of Fallot, truncus arteriosus, or neonatal Ross procedure, often require pulmonary hypertension precautions during care to minimize such elevations in pulmonary vascular resistance, while optimizing cardiac output.

General Treatment Approaches

A significant increase in PVR impedes blood flow and causes right ventricular strain that impairs right ventricular filling, producing right ventricular volume and pressure overload. Tricuspid regurgitation develops, and right atrial pressure rises as the right ventricle continues to fail.⁹⁶⁷

If the right ventricle is not able to increase pressure sufficient to maintain normal flow into the pulmonary circulation, left atrial filling decreases. As the right ventricular volume and pressure increase, the ventricular septum bows toward the left, into the LV outflow tract. The LV compliance will decrease, with an increased LV end diastolic and LA pressure. The pulmonary venous return will decrease, with further fall in cardiac output and coronary perfusion (a pulmonary hypertensive crisis).⁸⁴⁵ Treatment strategies for pulmonary hypertension management may be initiated when the systolic PAP is more than half the systemic systolic blood pressure.⁸⁴⁵

As noted, there are many neonates, infants and children at risk for the development of postoperative pulmonary hypertension. Neonates are particularly sensitive to changes in afterload and poorly tolerate sudden increases in pulmonary or systemic vascular resistance.⁹³⁸ In addition, some patients with apparently normal pulmonary vascular resistance may develop reactive pulmonary vasoconstriction.

Common critical care procedures that can increase pulmonary vascular resistance include hypoxia, sympathetic stimulation, acidosis, endotracheal suctioning, hypoventilation, and alveolar hyperinflation.⁹³⁵ Alveolar hypoxia is the most potent trigger for pulmonary vasoconstriction.⁷⁴⁵ Nurses must remain vigilant during noncardiac surgical procedures such as sedated echocardiograms, cardiac catheterization, endotracheal intubation, sedation, or exposure to anesthesia, which may lead to exacerbation of pulmonary hypertension.

In the preoperative setting caution is necessary in using additional oxygen and other pulmonary vasodilators in children with uncorrected left to right shunting lesions and identified pulmonary hypertension. Use of pulmonary vasodilators, such as oxygen, increase the volume of left-to-right shunts, increasing pulmonary blood flow, but this can also lead to worsening symptoms of congestive heart failure, pulmonary congestion and left heart overload. Excessive increases in pulmonary flow may also lead to a decrease in systemic perfusion in these children.

Postoperative Care

The nurse caring for the child postoperatively should be aware of the child's preoperative health status, intraoperative cardiovascular function, intraoperative echo findings and particular postsurgical complications, including anticipating the risk for pulmonary hypertension. Pulmonary hypertension and pulmonary vascular resistance can be elevated following cardiopulmonary bypass. Factors such as pulmonary vascular endothelial cell dysfunction, atelectasis, microemboli, hypoxic pulmonary vasoconstriction and release of potent vasoconstrictive substances can contribute to postoperative pulmonary vasoconstriction.^845,935,938 The length of cardiopulmonary bypass has also been implicated in the development of postoperative pulmonary vascular reactivity.⁹³⁵

Treatment of any patient at risk for pulmonary hypertension requires anticipatory care with elimination of factors that cause pulmonary vasoconstriction and administration of oxygen and other therapies that promote pulmonary vasodilation. The goals of care will include avoiding severe exacerbations in pulmonary vascular resistance and providing therapies to decrease pulmonary vascular resistance, with subsequent improvement of right ventricular function and cardiac output. Nurses will need to monitor continually for risks and signs of pulmonary hypertension. Therapies to avoid triggering pulmonary vasoconstriction will focus on optimizing oxygenation, ventilation, pain control, pulmonary vasodilating medications and sedation; these are summarized in Table 8-19.

Table 8-19 Strategies to Minimize Pulmonary Vasoconstriction^267,938

From Nieves J, Kohr L: Nursing considerations in the care of patients with pulmonary hypertension. Pediatr Crit Care Med 11(2 Suppl):S74-S78, 2010.

If a child's calculated PVR is high, or if the child is known to have increased PVR from preoperative studies or perioperative echocardiographic studies, meticulous attention to ventilation management and respiratory care are required. Precise management of ventilation in children with congenital heart disease is crucial and may have a significant effect on pulmonary vascular resistance; PVR can be controlled by manipulating aspects of ventilation.⁹³⁵

The child may be kept sedated with neuromuscular blockade for at least the first 24   hours after surgery to minimize the incidence of pulmonary hypertensive episodes, hemodynamic instability, and crisis.^42,935 Use of oxygen and controlled ventilation promotes pulmonary vasodilation and assists with stabilizing pulmonary artery pressure.^632,876 During mechanical ventilation, the tidal volume must be appropriate and barotrauma prevented. A normal functional residual capacity is optimal because it promotes lower PVR.⁹³⁵

Hypoventilation is avoided because it will increase PVR with the associated acidosis and hypercapnia. Hypoventilation may result from weaning ventilation, sedation, premature extubation, a significant leak around the endotracheal tube (can lead to variable tidal volume), or endotracheal tube obstruction or displacement. Pleural effusion, lobar collapse, and pulmonary infections are avoided or promptly treated; these can lead to alveolar hypoxia, hypercapnia, and acidosis with resultant increased pulmonary vasoconstriction. Low lung volumes (because of risk for atelectasis), excessive lung volumes, hyperinflation, and high PEEP are also to be avoided because they may provoke pulmonary vasoconstriction and increased pulmonary vascular resistance.^935,938

Blood gases will require close monitoring to prevent and treat the patient with pulmonary hypertension. Acidosis with a blood pH below normal is avoided as it can provoke pulmonary vasoconstriction. Alveolar hypoxia must be avoided; an alveolar PaO₂ below 50 to 60   mm Hg provokes pulmonary vasoconstriction. Prompt detection and treatment of acidemia and hypoxemia are required. An arterial PaO₂ of greater than 100   mm Hg is expected in children with a biventricular cardiac repair who receive supplementary oxygen.

Oxygen is a potent pulmonary vasodilator.⁹³⁵ In infants, high levels of inspired oxygen, especially 100% oxygen (FiO₂ of 1.0), decrease pulmonary vascular resistance.⁹³⁵

Oxygen therapy is used with caution in the patient with unrepaired single ventricle physiology (e.g., truncus arteriosus or hypoplastic left heart syndrome) because pulmonary vasodilation can cause pulmonary over-circulation with systemic hypoperfusion (see section, Specific Diseases, Single Functioning Ventricle). In single ventricle physiology the balance between systemic and pulmonary blood flow must be carefully controlled through manipulation of PVR. Cyanotic heart disease is present (no air can be allowed to enter any IV line), and a “balanced” shunt is generally present if systemic hemoglobin saturation is maintained near 80% with a PaO₂ of near 40   mm Hg.⁹³⁵ The patient care team should develop individualized target parameters (such as pH, PaCO₂, PaO₂, central venous pressure) for each patient with or at risk for pulmonary hypertension that require notification of the cardiac care team and prompt intervention.

Alkalosis is a pulmonary vasodilator. Serum pH is the dominant factor causing pulmonary vascular tone changes, not the PaCO₂.⁷⁸⁴ A mild alkalosis (pH approximately 7.5) can be created with mechanical hyperventilation to reliably decrease PVR in infants.⁹³⁵ However, hypocarbia will decrease cerebral perfusion, so should be used with caution. Alkalosis can also be achieved by adding a continuous infusion of sodium bicarbonate.⁷⁸⁴ A PaCO₂ less than 25   mm Hg should be avoided because of the risk of compromise in cerebral oxygenation and perfusion.

Endotracheal suctioning has been identified as a strong stimulus provoking acute pulmonary vasoconstriction.⁹³⁵ Premedication with IV fentanyl can help to block the stress response.³⁷¹ Hyperventilation with the delivery of 100% inspired oxygen should be provided before and after each suction pass. Hyperoxygenation has been shown to reduce suction-induced hypoxia⁶⁶⁹ and can promote pulmonary vasodilation, so additional manual ventilator breaths with higher oxygen flow should be provided before and after every suction pass. Inline, closed suctioning systems allow suctioning while maintaining a continuous gas flow and PEEP as well as lung volume.⁷⁸⁸ However, the nurse must be adept with the use of such a system. If the intubated child has an open suctioning system, two people should be available to suction the patient. One person provides hand or mechanical ventilation and ensures that oxygenation is maintained. The second provides skilled, sterile, gentle suctioning,⁷⁸⁸ while monitoring heart rate, end tidal CO₂, systemic arterial oxygen saturation, and hemodynamics.

A pulmonary hypertensive event must be detected promptly to avoid the rapid deterioration to a pulmonary hypertensive crisis. If the patient deteriorates during suctioning, the suctioning is stopped and support of optimal airway, oxygenation, and ventilation provided. Hand ventilation with 100% oxygen is provided until the child's heart rate, color, and cardiovascular function are stable. During a pulmonary hypertension crisis, therapies include: administration of 100% oxygen, intravenous fentanyl bolus, additional sedation, neuromuscular blockade, alkalinization, and efforts to precisely control ventilation and improve cardiac output. The bedside nurse should also verify that infusions of vasodilator therapies (inhaled and intravenous) continue without interruption. Inotropic support, if used, may further escalate PVR. Initiation of inhaled nitric oxide may be required.

During weaning of mechanical ventilation the child's pulmonary pressure and systemic perfusion should be monitored carefully because hypoventilation will produce alveolar hypoxia, hypercapnia, and acidosis, and can result in pulmonary vasoconstriction with decreased RV function. Prevention or prompt correction of acidosis will be required. An arterial PaO₂ of greater than 100   mm Hg is expected in the child with a biventricular repair receiving supplementary oxygen therapy. During the weaning of oxygen therapy, the arterial blood gas and pulse oximetry is monitored for decreasing PaO₂ and arterial oxyhemoglobin desaturation. The care team should be notified if the PaO₂ is less than 90   mm Hg, the arterial oxyhemoglobin saturation is less than 94%, or if a previously identified critical parameter develops. A planned, controlled extubation process is needed with continuous monitoring of systemic perfusion and staff ready to manage in the event of decompensation.⁸⁴⁵ Following extubation, supplementary oxygen and adequate analgesia (to maximize efforts for pulmonary toilet and minimize excessive oxygen consumption) are used.

Sedation and pain control are provided to minimize exacerbation of pulmonary vasoconstriction. Agitation and pain can cause stimulation of the sympathetic nervous system with subsequent pulmonary vasoconstriction.⁹³⁵ Continuous infusions of sedation with intermittent bolus doses are required while mechanical ventilation is provided. Narcotic bolus doses of fentanyl have been shown to blunt the stress response³⁷¹ associated with endotracheal suctioning. Pain resulting from chest tube removals, suctioning, venipuncture, intravenous catheter changes or infiltration, or large dressing or tape removals can lead to agitation and pain, with additional risk for pulmonary hypertension; fentanyl premedication should be considered, particularly in labile patients. Continuous infusion of fentanyl (5   mcg/kg per hour) with doses as high as 10 to 15   mcg/kg per hour have been used to treat patients with labile pulmonary hypertension.⁹³⁵ Neuromuscular blockade with intravenous muscle relaxants may be required.

Normothermia is maintained to minimize additional oxygen consumption. Bathing, discomfort, and excessive stimulation are avoided until the risk for pulmonary hypertensive episodes has passed.

When a pulmonary artery (PA) catheter is present, the pulmonary artery pressure (PAP) can be monitored continuously with rapid detection of alterations. The effect of interventions on the PAP can be monitored, including the addition or weaning of therapies.^935,938 PVR can be calculated and mixed venous oxygen saturation measured.¹³² Guidelines for PA line management and removal have been published.¹³²

Fluid volume status requires ongoing assessment. Right ventricular dysfunction may require a high right atrial pressure and CVP to optimize RV preload, thus maintaining adequate cardiac output. Both hypovolemia and hypervolemia can alter right ventricular preload, leading to decreased cardiac output. Presence of a sinus rhythm is essential. In the patient with severe RV dysfunction and pulmonary hypertension, tachyarrhythmias with loss of atrioventricular synchrony further critically impair preload and stroke volume, decrease cardiac output, and require immediate treatment (see section, Arrhythmias).⁹⁶⁷ Development of bradycardia is ominous and may result from development of profound myocardial hypoperfusion and ischemia.⁸⁰⁴

Nurses should anticipate higher risk of pulmonary hypertensive events or crises developing with extubation, intubation, weaning oxygen, weaning ventilator support (caused by rise in PaCO₂, fall in PaO₂, and development of alveolar hypoxia), weaning of sedation or analgesia, discontinuing of neuromuscular blockade, weaning pulmonary vasodilators (nitric oxide), and with painful procedures, in particular suctioning. Continuous monitoring is essential.

Nurses can provide care within a set of individualized parameters identified by the care team for each patient. These may include monitoring for identified specified therapeutic limits, including the highest acceptable pressure (e.g., for right atrial and pulmonary artery pressure), the lowest acceptable invasive or noninvasive oxygenation and carbon dioxide parameters (e.g., lowest PaO₂ or arterial oxyhemoglobin saturation allowed, highest end tidal CO₂), blood gas limits (e.g., for target pH, PaCO₂), mixed venous oxygen saturation, or serum lactate limits. These limits will be valuable during the weaning process, when pulmonary hypertensive events and hemodynamic instability may develop.

Selected patients may have a residual atrial communication (“atrial pop-off”) in place postoperatively to allow some right-to-left shunting of blood when either right ventricular end-diastolic pressure or right atrial pressure increase.⁹³⁸ This atrial communication may be present following newborn truncus arteriosus repair, when RV function and pulmonary hypertension are anticipated or with fenestrated Fontan procedures. This right-to-left shunt can optimize left ventricular preload, preserve cardiac output, and cause transient systemic arterial desaturation.⁸⁴⁵ Because this shunt allows systemic venous blood to enter the systemic arterial circulation, no air can be allowed to enter any IV line due to risk of systemic emboli. As the RV function improves and elevated pulmonary vascular resistance resolves, the patient will show improved arterial oxygen saturations because of less right-to-left shunting.⁹³⁸

Drug Therapy

The causes for pulmonary hypertension in the critical care unit are frequently multifactorial; therefore, multiple approaches to therapies are required for the best care.⁹³⁸ Combinations of inotropic support and vasodilator therapy may be used to treat pulmonary hypertension by the inhaled, intravenous, or oral routes of delivery. The optimal medications produce pulmonary vasodilation, decreased PVR, lower PAP, and resultant ease of RV workload without systemic arterial hypotension. Ultimately this will increase pulmonary blood flow and improve cardiac output. Inhaled nitric oxide therapy is common. Unfortunately, most parenteral and oral vasodilators dilate both arteries and veins; thus, this therapy may produce complications such as profound systemic hypotension and critical lowering of coronary perfusion pressure.⁹³⁸ If vasodilators are administered continuously, it is important that the child's fluid volume status be assessed, because hypotension is more likely to occur during therapy if hypovolemia is present.

New and Evolving Therapies

Additional therapies are under investigation for the treatment of pulmonary hypertension.^6,274,404 Major pathways at the cellular level have been discovered to contribute to pulmonary hypertension, including the vasodilating nitric oxide pathway and the prostaglandin pathway. The vasoconstrictor pathway effects are produced by endothelins. Pulmonary hypertension is thought to be a result of an imbalance of vasodilation or vasoconstriction. Therapeutic drug therapies are under investigation that will help, individually or used in combination, to improve the balance between pulmonary vasodilation and pulmonary vasoconstriction.⁹⁶⁷ The medications and treatment pathways are reviewed in detail by Humbert et al³⁹⁷ and Barst et al.⁶⁰

Sildenafil (Viagra) is used for treatment of pulmonary hypertension by promoting pulmonary vasodilation. This drug is approved by the FDA for treatment of adult pulmonary hypertension. Sildenafil has a somewhat selective pulmonary vasodilating effect.⁹³⁵ An oral/nasogastric dose 0.5   mg/kg every 4   hours was found to be as effective as 2.0   mg/kg.⁷²⁰ To reduce development of rebound pulmonary hypertension with weaning of NO, the dose is given 1 to 1.5   hours before the NO is discontinued. Peak drug effect occurs in 30 to 60   minutes,⁹⁶⁷ with a half-life of 4   hours. Sildenafil is contraindicated in patients receiving oral or intravenous nitrates because of the risk of refractory hypotension.³⁸ In children, the optimal dose for sildenafil is likely to be 0.3 to 1.0   mg/kg three times/day, but is yet to be determined.²⁷⁴ Pediatric congenital heart disease clinical trials in the United States are in progress.

Bosentan (Tracleer) is used as chronic oral therapy for pulmonary hypertension in adults.⁶ It blocks pulmonary vasoconstriction by endothelin, a potent pulmonary vasoconstrictor, endogenously secreted by the vascular endothelium. Bosentan was first found to be successful in adults in the Breathe 2006 study,²⁹⁵ in which patients with Eisenmenger syndrome showed significant improvement in exercise capacity and hemodynamics, fewer symptoms, but no change in pulmonary vascular disease. Bosentan is administered under monthly surveillance of hepatic function studies because it can alter hepatic function. Pregnancy is contraindicated.

Letairis (Ambrisentan and Sitaxsentan), are additional orally administered endothelin blocker medications.⁶ Letairis was approved by the FDA for use in adults in June 2007. Pediatric studies for endothelin blocking agents are in progress.

Epoprostenol (Flolan) is a prostacyclin producing pulmonary vasodilation, approved by the FDA for treatment of chronic severe pulmonary hypertension.⁴⁰⁴ This intravenous drug is used most often for chronic outpatient therapy.⁹³⁸ In the immediate postoperative unstable patient it can precipitate a systemic hypotension. Flolan is costly, has specific guidelines for initiation with dose titration, and must be administered by continuous IV infusion because it has such a short half life (2 to 3   min).^404,613,967

Additional prostacyclin analogues have been shown to be effective when studied in adult patients. These include subcutaneous Treprostinil (Remodulin), a subcutaneous infusion with a longer half-life (3 to 4   hours).⁹⁶⁷ Remodulin was approved for use by the FDA in 2002. An inhaled prostaglandin drug, Iloprost (Ventavis), can be given by nebulizer treatments 6 to 9 times/day, lasting 10 to 15   minutes each.⁴⁰⁴ Iloprost was FDA approved for adults in 2004, and limited studies are available in children. Each of these medications is currently used as an “off label” therapy in children.

Transition and Advanced Care

Patients with pulmonary hypertension may be admitted to the critical care unit for postoperative care, after cardiac catheterization, following non-cardiac surgery procedures, for respiratory illness, or when pulmonary hypertensive drugs are initiated or changed, necessitating nurses to closely monitor for responses to therapy. Communication and collaboration of current status, response to treatments, and plan of care involving all team members is imperative to avoid exacerbation of pulmonary hypertension, which can become life-threatening. Some advanced concepts in the management of these patients are listed in Box 8-13.

Children with severe pulmonary hypertension often receive medications in the home setting, including continuous oxygen and intravenous infusions, to promote pulmonary vasodilation.⁷⁴⁵ Nurses must ensure that home medications for pulmonary hypertension are not interrupted upon hospital admission, particularly those medications with a short half-life, such as IV Flolan. Families require comprehensive nursing education focusing on their child's PHTN management.

Arrhythmias

Arrhythmias are the most common cause of sudden cardiac death in ACHD,³⁵² and affect up to 50% of adults with congenital heart disease.⁹⁴⁶ Patients with uncorrected and corrected congenital heart disease may present with arrhythmias. For example, patients with uncorrected atrial septal defect may develop atrial fibrillation or flutter. Ninety percent of patients with late sudden cardiac death related to arrhythmias have tetralogy of Fallot, D-transposition of the great arteries, coarctation of the aorta, or aortic stenosis.³⁵² Antiarrhythmic therapy can be used to treat specific rhythms, but proarrhythmic effects must be monitored. Therapies are detailed by Harris.³⁵² Treatments can include medications, cardiac pacing, implantation of cardiac defibrillators, or surgical interventions such as the Maze procedure⁴⁶ in the management of patients' status post right atria to pulmonary artery Fontan procedure with subsequent development of atrial re-entry tachycardia or atrial fibrillation.⁸⁶⁴ The Maze procedure or Cox-Maze III procedure involves cryoablation (−160   °C) as well as surgical atrial incisions of the abnormal conduction pathways during open heart surgery.⁸⁶⁴

Cyanosis

Cyanosis can affect patients with uncorrected cyanotic lesions, those with uncorrected shunt lesions and Eisenmenger syndrome, those with cyanotic heart defects and palliative procedures (e.g., systemic artery to pulmonary artery shunts, systemic vein to pulmonary artery shunts, central aorta to pulmonary artery shunts [e.g., Waterston, Potts shunt]), Fontan-type procedures with fenestrations, or complex surgical repairs where atrial fenestration remains.

Polycythemia with hematocrit rising to 60% or above may produce symptoms of headache, dizziness, dyspnea, fatigue, and neurologic changes.²¹⁵ Dehydration must be avoided because of hyperviscosity and risk for stroke or emboli. All intravenous systems require meticulous removal of any air or clots because of risk of paradoxic emboli to the brain, kidney, or heart.²¹⁵ Thrombocytopenia and coagulopathies are common (see Hypoxemia Caused by Congenital Heart Disease).

Phlebotomy is not routinely performed unless the patient becomes symptomatic. An equal volume of whole blood may be removed and replaced with saline or albumin. Potential complications of phlebotomy include stroke, seizures, and death.⁸⁶⁴

If the cyanosis is associated with pulmonary hypertension (e.g., Eisenmenger syndrome), the patient requires pulmonary hypertensive care precautions. In addition, medical management is required (see the following).

Cyanotic adults may also develop hyperuricemia, gouty arthritis, and altered renal function requiring treatment with allopurinol or colchicines.⁸⁶⁴ Hypoperfusion and chronic hypoxia also lead to renal disease.²¹⁵

Pulmonary Hypertension

Pulmonary hypertension can develop as a consequence of congenital heart disease in 15% to 30% of patients,⁵¹¹ those repaired at a later age, or those with significant unrepaired left-to-right shunts.²¹⁵ Patients with single ventricle with Glenn and Fontan palliations or staged correction require the lowest possible pulmonary resistance for survival.⁵¹¹ Evaluation of the status of the pulmonary vascular bed may include cardiac catheterization with measurement of the reactivity to pulmonary vasodilator therapy (see Common Diagnostic Tests, Cardiac Catheterization).

Patients may demonstrate hypoxemia as a result of pulmonary hypertension and progression to Eisenmenger syndrome with reversal of the intracardiac shunt. This pulmonary hypertension is typically unresponsive to oxygen.⁹²⁶ Pulmonary vasodilator treatments include oxygen therapy to treat hypoxemia (particularly at night),²¹⁵ inhaled nitric oxide or epoprostenol,⁵¹¹ prostacyclines, endothelin receptor antagonists (Bosentan),⁹¹² and phosphodiesterase five inhibitors (Sildenafil).⁵¹¹

Pulmonary hypertensive precautions are vital during periods of illness or procedures requiring anesthesia because these situations include risk for conditions such as acidosis, alveolar hypoxia, pain, agitation, and hypoventilation that may provoke pulmonary vasoconstriction. Goals of care will include lowering PAP, decreasing PVR and RV afterload while maximizing RV function, ultimately improving cardiac output. Nursing care will focus on optimizing ventilation, improving RV function, providing adequate sedation, treating pain, avoiding metabolic and respiratory acidosis, avoiding atelectasis, avoiding anemia, and minimizing energy expenditure needs.⁵¹¹ In the immediate cardiac surgery postoperative period, reactivity of the pulmonary vascular bed is heightened.⁵¹¹ Support of systemic blood pressure may be required with use of agents such as norepinephrine to maintain coronary perfusion.⁵¹¹

Adequate hydration is essential, and hypotension must be avoided.²¹⁵ Strategies for care attempt to decrease pulmonary artery pressure, enhance right ventricular function, and avoid development of pulmonary hypertensive events or crises with subsequent right ventricular failure (see Sectons “Pulmonary Hypertension” and “Management”).

Selected Eisenmenger syndrome patients may require phlebotomy because of symptomatic hyperviscosity, with specific guidelines to avoid acute adverse reactions and even death. For further information, see Daniels²¹⁵ and Warnes et al.⁹²⁶

Conduit Obstruction

Extracardiac conduits and baffles can develop obstruction over time, requiring reintervention. The conduits connect the subpulmonary ventricle to the pulmonary arteries in tetralogy of Fallot and other complex congenital heart disease.³⁹⁸ Treatments include cardiac catheterization intervention (balloon angioplasty or stent implantation).

Conduit replacement is possible with early low mortality; of patients reoperated at a mean age of 9.6 years, 55% were free from conduit reoperation at 10 years, and 31.9% at 20 years.²²⁸ Developments in percutaneous pulmonary valve replacement have resulted in avoiding surgical revisions in many of the cases treated⁵⁵⁰ and are FDA approved since 2009.⁵⁹⁸ Patients with conduits require lifelong periodic reevaluation⁵²⁶ in adult CHD clinics.^215,926

Bicuspid Aortic Valve

Bicuspid aortic valve is the most common congenital lesion, present in about 1% to 2% of the population.^215,926 The lesion can progress over time, requiring patients to be monitored for potential development of aortic valve calcification, regurgitation, and stenosis. Aortic root dilation and dissection may also develop.⁹²⁶

When indicated, therapeutic interventions may include interventional catheterization balloon valvuloplasty, or surgery for aortic valve intervention or replacement, or a Ross procedure (see section, Specific Diseases, Aortic Stenosis).

Coarctation of the Aorta

Coarctation of the aorta may be diagnosed late in life, and the patient may present with upper extremity hypertension with decreased lower extremity pulses and blood pressures. Late complications of repair include recoarctation, aortic aneurysm or dissection, and sudden death. Systemic hypertension has been reported in up to 70% of patients after coarctation repair,⁴²⁷ and must be differentiated from hypertension caused by recoarctation through use of physical exam (arm and leg blood pressure gradients) and diagnostic studies. Systemic hypertension may occur during rest or activity, and may require medical therapy.^215,926 Blood pressures may be decreased in the left arm if a left subclavian artery flap was used in the original repair. The cause of the high risk of hypertension and aortic dissection is unknown.²¹⁵

Recoarctation incidence is 8% to 54% and in selected cases may be treated with transcatheter therapy (stent, angioplasty).²¹⁵ An aortic aneurysm may form in the left subclavian flap or patch aortoplasty repair site.¹⁹⁷ Bicuspid aortic valve is present in about half of patients with coarctation of the aorta.^527a These bicuspid valves can develop significant stenosis or regurgitation.¹⁹⁶

Atrial Septal Defect

The adult with an undiagnosed atrial septal defect may present with a cerebrovascular accident or transient ischemic attack following a paradoxic embolism across the atrial septal defect.²¹⁵ Factors leading to arrhythmia development include chronic right heart volume overload, ventricular dysfunction,⁹²⁶ late date at operation, or the presence of pulmonary hypertension.³⁵² About 50% of those patients with preoperative atrial arrhythmias have postoperative arrhythmias, particularly if they are 40 years old or older at the time of surgery. The presence of atrial arrhythmias can result in need for anticoagulation.³⁵² Transcatheter device closure is possible for many with secundum type lesions (see Specific Defects, Atrial Septal Defect).

Adult patients presenting with sinus venosus or primum defects require surgical repair.⁸⁰² Pulmonary hypertension may be present in the unrepaired adult. Atrial septal defects repaired early in life are typically symptom free, but atrial arrhythmias (fibrillation or flutter) may develop in the operated^608,926 and the unoperated patient.^352,926

Tetralogy of Fallot

Tetralogy of Fallot is the most common complex defect with the longest survival history.⁹⁴⁶ Most adult patients have undergone surgical repair in childhood or even adolescence,³⁵² and some have undergone initial palliative shunt procedure. Some patients may have a right ventriculotomy with a patch or a valved conduit between the right ventricle and pulmonary artery, whereas others have surgical removal of the pulmonary valve with a transannular patch and resultant free pulmonary regurgitation.

If the pulmonary valve is present, it may become insufficient or stenotic and the distal pulmonary arteries obstructed. Postoperative patients may develop arrhythmias. Atrial arrhythmias (flutter, fibrillation or supraventricular tachycardia) develop in up to one third of patients.⁷⁴³ Ventricular tachycardia and sudden cardiac death are known complications.^215,926 By 35 years after surgery, the estimated risk for sustained ventricular tachycardia is 11.9%, and for sudden death is 8.3%.³⁰²

RV size correlates with QRS duration. The combination of older age at correction and QRS duration of 180   ms or longer, as well as older age at initial repair³⁵² predict risk of sustained ventricular arrhythmias and sudden cardiac death.³⁰³ Right bundle branch block (RBBB) is a common finding in patients who had surgical correction many years ago, but in itself is not predictive of a worse prognosis (although RBBB with QRS 180 ms or higher is).³⁵²

The most common problem following surgical correction of tetralogy of Fallot is pulmonary regurgitation, which causes chronic right ventricular volume overload and may progress to right ventricular enlargement and systolic dysfunction.^215,926 Severe right ventricular dilation and mild global right ventricular systolic dysfunction are associated with higher risk for adverse clinical outcomes in patients with repaired tetralogy of Fallot.⁴⁸² Progressive aortic root dilation and potential for aortic dissection may also develop.²¹⁵ Pulmonary regurgitation is the most common reason for late reoperation.⁹⁴⁶

Tetralogy of Fallot survivors require lifelong monitoring, including regular evaluation with MRI,^482,926 for each of these potential complications and to avoid progression of decreased cardiac function. Surveillance for potential arrhythmias is required. Treatment for arrhythmias includes cardiac pacing, use of implantable cardioverter/defibrillators, antiarrhythmic therapy or radiofrequency ablation, or arrhythmia intervention during reoperation³⁵² for pulmonary valve replacement. Selected cases may undergo transcatheter pulmonary valve replacement via cardiac catheterization.⁵⁹⁸ Long-term survival at 32 years is 86%.⁶⁴¹ Tetralogy of Fallot is the most common diagnosis for patients with implantable cardioverter defibrillators.⁴⁶⁷

Transposition of the Great Arteries

Atrial switch for d-transposition of the great artery (Mustard or Senning procedure) requires extensive atrial incisions and suture lines.³⁵² As a result, patients who undergo these procedures require lifelong regular monitoring^215,926 for development of arrhythmias (atrial tachycardia, sick sinus syndrome) and are at risk for sudden cardiac death. Loss of sinus rhythm is common, with only 18%⁹⁵⁰ to 40%³¹⁰ of survivors in sinus rhythm 15 to 20 years after surgery. Pacemaker implantation is anticipated in about one-fifth of adults with long-term followup after a Mustard procedure.³⁵²

Pacemakers can be used to treat bradyarrhythmias or tachyarrhythmias,³⁵² and radiofrequency ablation or medications can be used to treat tachyarrhythmias.²¹⁵ Despite close followup, about 7% of patients have sudden cardiac death after atrial switch.⁹⁵⁰

After an atrial switch procedure for d-transposition of the great arteries, the right ventricle is the systemic ventricle (pump) for life and progressive dysfunction develops by the second or third decade of life in about 15% of postoperative patients,⁹⁵⁰ with progression to ventricular arrhythmias in the failing ventricle.³⁵² The tricuspid valve, exposed to systemic pressures, can become dysfunctional. Narrowing in the left ventricular outflow area can also develop.

Reconstruction of the atrial flow pathways can rarely result in the serious complication of baffle obstruction of pulmonic or systemic venous return.²¹⁵ Baffle leaks causing atrial shunting are common but they are often small.²¹⁵ If despite optimal medical management the ventricular dysfunction becomes severe, either staged surgical anatomic correction (arterial switch procedure) or cardiac transplant may be planned. Patients with d-TGA, VSD, and pulmonary stenosis repair will have undergone a Rastelli procedure with a conduit between the right ventricle and pulmonary artery, that will require continued surveillance.

Arterial switch became the treatment of choice for transposition of the great arteries in the 1980s. Follow-up shows good systemic ventricular function and sinus rhythm,⁹⁴⁶ although the patients having additional VSD repair are reported at higher risk for arrhythmias.³⁵⁹ Potential long-term issues include the need for serial assessment of ventricular function and surveillance for the development of arrhythmias, stenosis at the great vessel suture sites,⁹⁴⁶ neo-aortic root dilation, and development of valvar regurgitation.¹⁸⁶

Coronary artery lesions, found in 5% of patients following the arterial switch operation, are progressive and can be treated by coronary angioplasty or surgery.⁷¹⁹ Coronary atherosclerosis remains a concern and requires careful followup.⁶⁹² The progression of coronary artery disease after the arterial switch procedure is unknown. The most common cause for reoperation is pulmonic stenosis.⁵⁴⁷ Survival at 15 years after the initial operation is 88%,⁵⁴⁷ but long-term outcome is unknown.^186,215,926

Single Ventricle

Although it is a rare condition, patients with a single ventricle account for a disproportionate share of the morbidity and mortality found in adults with congenital heart disease.⁹⁴⁶ Single ventricle includes diagnoses of tricuspid atresia, mitral atresia, double inlet LV, hypoplastic right or left ventricle, or single ventricle. These patients will remain cyanotic until they undergo Fontan-type correction. The first patients with a Fontan-type staged palliation and correction are now in their fourth decade of followup.⁴⁶⁶ Young adults with a univentricular heart who are unrepaired have a poor prognosis.²¹⁵

The original Fontan procedures (1970s) connected the right atrium directly to the pulmonary arteries, or connected the right atrium to the right ventricle, exposing the right atrium to high systemic venous pressure.³⁵² Over time elevated right atrial pressure can lead to right atrial enlargement, hypertrophy, and slowed atrial conduction.³⁵² A severely enlarged right atrium is often seen in patients with a classic Fontan procedure and a failing Fontan circuit, which contributes to development of medically resistant complex atrial arrhythmias.⁹²⁶ Atrial distension and surgical incisions with subsequent scarring also contribute to arrhythmia formation.³⁵² Atrial tachycardia and sick sinus syndrome may be observed, particularly in those patients with the right atrium included within the Fontan pathway.³⁵² Atrial tachycardia can develop in up to 50% of adults with Fontan procedure,^226,926 and sinus bradycardia or junctional escape rhythm has been reported in up to 15% of patients.³⁵² Sustained atrial arrhythmias may cause patients to present with congestive heart failure, low cardiac output, and can lead to development of atrial thrombi.³⁵² Anticoagulation therapy is often required in the presence of sustained atrial arrhythmias.³⁵² Therapy for arrhythmias can include antiarrhythmic therapy, pacemaker (typically epicardial if ventricular), radiofrequency ablation, or arrhythmia intervention during reoperation.³⁵²

Many long-term complications have been reported following single ventricle palliations. Outcomes have improved, but systemic ventricle dysfunction may develop, particularly with a right ventricular systemic pump.³¹¹ The less efficient right atrium to pulmonary artery Fontan type surgical procedure has become obsolete,³¹¹ replaced by the total cavopulmonary artery connections (superior vena cava to pulmonary artery shunt plus intraatrial lateral tunnel or extracardiac conduit).⁴⁶⁷ The use of external conduits from the inferior vena cava to the pulmonary artery results in a sutureless right atrium, and potentially may decrease incidence of postoperative atrial arrhythmias.³¹¹ Some patients may have a lateral tunnel connecting the inferior vena cava to an intraatrial tunnel, then the pulmonary arteries. Long-term data are not yet available to define long-term outcomes of these two procedures.³¹¹

Pulmonary vein compression, pulmonary artery stenosis, Fontan pathway obstruction, atrioventricular valve insufficiency, arrhythmias, hepatic dysfunction, hepatic fibrosis, and cirrhosis may each develop after the Fontan procedure.^47,215,926 Protein losing enteropathy is reported in 3.7% of patients following Fontan-type correction and is associated with a poor clinical course,³¹¹ with a 50% 5-year mortality after the diagnosis.^612,926

The function of the single systemic ventricle and atrioventricular valve can deteriorate, and must be monitored closely, particularly in those patients with a right ventricle performing a lifetime of systemic work. Heart failure risk in Fontan patients is reported to be higher in those patients with the (single) morphologic right ventricle functioning as the systemic ventricle.⁹⁴⁴ Currently, many patients with the Fontan operation have hypoplastic left heart syndrome, with a resultant systemic right ventricle, creating concerns regarding long-term right ventricle status.³¹¹

Arterial oxygen saturations will be monitored for the potential late development of cyanosis caused by fenestration of the Fontan or the development of pulmonary arteriovenous malformations (AVM), systemic venous collaterals, or baffle leaks.²¹⁵ Patients developing cyanosis²¹⁵ or residual stenosis may require diagnostic or therapeutic cardiac catheterization. Cardiac magnetic resonance imaging (MRI) cannot be completed if the patient has a cardiac pacemaker.

The failing Fontan circuit may require surgical revision with conversion to an extracardiac Fontan and a form of the Maze procedure for treatment of intractable atrial tachycardia.⁹²⁶ Recent reported perioperative mortality is 1%,^46,226 and late mortality is 5%.⁴⁶

Survival at 25 years after Fontan-type correction has been reported at 70%.⁴⁶⁷ The most frequent causes of late death in Fontan patients are sudden death (9.2%), thromboembolism (7.9%), and heart failure (6.7%), with an arrhythmic origin presumed for the sudden deaths.⁴⁶⁷ Absence of aspirin or warfarin therapy is a predictor of death caused by thromboembolic event.⁴⁶⁷ The risk for thromboembolic death increases sharply 15 years after Fontan surgery.⁴⁶⁷ All single ventricle patients require continuous lifelong care in a center with expertise in ACHD care. In the presence of single ventricle dysfunction or protein-losing enteropathy, a heart transplant may be beneficial.⁹²⁶ More information is needed regarding long-term outcome of these patients.

Procedures

Cardiac catheterization may be required in adults with CHD for hemodynamic assessments. Interventions are commonly performed for complex pulmonary artery stenosis, baffle stenosis, or residual aortic narrowing. Shunting defects, including fenestrations, may be sealed with devices (see Common Diagnostic Tests, Cardiac Catheterization). Pulmonary valves and aortic valves are now replaced by transcatheter interventions in selected cases. Pediatric electrophysiology studies to detect and treat atrial or ventricular arrhythmias may include implantation of a cardiac pacemaker with possible cardioverter defibrillator.³⁸⁸

Postoperative Care

Comprehensive guidelines are available for the perioperative assessment and management of patients with adult congenital heart disease undergoing noncardiac surgery.¹⁹⁶ When cardiovascular surgery is required, reoperations are the most common type of surgery needed.⁸⁰² High-risk patients require close postoperative surveillance in a critical care or coronary care unit, particularly patients with cyanosis, pulmonary hypertension, ventricular dysfunction, or single ventricle.¹⁹⁶

The most common reported complication in the postoperative cardiac surgery adult (occurring in 10.8% of patients) is atrial arrhythmias.¹ The postoperative team must carefully monitor the patient's volume status, hemodynamics, and electrolyte balance, and be observant for evidence of hypoxemic pulmonary hypertensive episodes or crisis and be aware of all drug therapies required. Each cardiac lesion carries risks of particular rhythm disturbances, and unexpected arrhythmias may occur at any time.

Conduction anomalies are common in adults with uncorrected cyanotic CHD,⁸⁰² including ventricular or supraventricular ectopy. Perioperative development of arrhythmias can lead to sudden, severe low cardiac output. Immediate evaluation and prompt treatment are required.⁸⁰² Monitoring for development of cardiac ischemia includes monitoring for ST segment changes and ventricular ectopy. Atrial and ventricular pacing wires can assist in management (see Arrhythmia Detection and Management).

Bleeding is a potential risk following reoperation, particularly in the patient with longstanding cyanosis.⁸⁰² Reoperation requires incisions through vascular scar tissue and chronic hypoxemia is associated with thrombocytopenia and thrombocytopathia. In addition, patients with chronic hypoxemia may demonstrate a decrease in vitamin K-dependent clotting factors. For these reasons, bleeding should be anticipated and plenty of blood should be available for postoperative blood replacement.

Cardiac reserve may be limited in many cyanotic patients, and excessive blood loss can rapidly cause hemodynamic instability. Target hemoglobin values and plans for coagulation factor replacement are individualized based on the specific congenital lesion, operative interventions, and associated risk factors. A patient with expected residual cyanosis cannot tolerate anemia, because it decreases oxygen-carrying capacity and reduces oxygen content and likely oxygen delivery.

The risk of perioperative low cardiac output is increased in the presence of chronic hypoxemia, ventricular hypertrophy, chronic volume or pressure overload, ventricular dysfunction, and arrhythmias. In the postoperative period, reactivity of the pulmonary vascular bed is heightened,⁵¹¹ so pulmonary hypertension precautions are vital (see section, Pulmonary Hypertension).

Pulmonary hemorrhage may develop with interventions that increase pulmonary blood flow, particularly after interventional cardiac catheterization. Mechanical ventilation and pulmonary support are required. Development of pneumonia, infection, fever, thrombosis, or pulmonary edema can seriously destabilize the patient with ACHD, even after a minor procedure. Supplementary oxygen can help to decrease the pulmonary vascular resistance, although if cyanotic heart disease is present it may not increase the arterial oxygen saturation.¹⁹⁶ Parameters for acceptable and expected oxygen saturation levels and PaO₂ are required.

Smoking can compromise pulmonary function preoperatively and postoperatively. Encourage pulmonary toilet hourly while awake with incentive spirometry, and encourage the patient to get out of bed and walk or at least sit in a chair as soon as possible. Intermittent pneumatic compression or the use of antiembolism stockings should be used to reduce the risk of deep vein thrombosis (DVT).¹⁹⁶

Risk of DVT is increased with prolonged bedrest, neuromuscular blockade, and limited range of motion. Early ambulation is optimal. Monitor for signs of DVT, including redness or pain in the leg calves. Signs of pulmonary embolus include sudden dyspnea, tachypnea, increased oxygen requirement, and rales. An arterial blood gas will not establish the diagnosis. Massive pulmonary embolism can result in acute right ventricular failure, low cardiac output, and myocardial ischemia with ST segment changes. Diagnosis is confirmed by lung perfusion scan or pulmonary angiogram. Treatment includes immediate, heparinization, and hemodynamic supportive care. In acute situations, fibrinolytics (recombinant tissue plasminogen activator or rTPA) are administered. Cardiopulmonary bypass may be employed to remove the embolus (pulmonary embolectomy).

Renal dysfunction is a known risk in patients with chronical cyanotic hypoxemia.⁸⁰² Cardiopulmonary bypass can further exacerbate renal dysfunction. Perioperative care includes maintaining optimal cardiac output with careful fluid balance and support of systemic perfusion. Volume replacement requires normal saline infusions typically of 500 cc or more (10 cc/kg), administered as a bolus to optimize cardiac filling pressures. Infusion by syringe injections (often used for pediatric patients) does not allow administration of sufficiently large volumes when resuscitation is required.

Relative hypovolemia can result from rewarming and vasodilation, fever, increased capillary permeability, and use of vasodilators. Signs can include sinus tachycardia, decreased central venous or intracardiac pressures, and signs of decreased perfusion.

Standard medication doses for adults are used, including doses for resuscitation drugs, antiarrhythmic therapy, and antibiotics. Intravenous drug infusions in the adult can be specifically concentrated by the clinical pharmacist to avoid excessive fluid volume administration. Doses must be titrated individually with consideration of any renal or hepatic dysfunction.

Cyanotic patients are at greater risk of postural hypotension because of a greater right-to-left shunt.¹⁹⁶ Changes in movement should be gradual.

Effective pain management is essential to minimize catecholamine surges.¹⁹⁶ The patient with ACHD may have sensitization to and greater fear of painful procedures because of a previous history of inadequately managed pain during prior surgeries or hospitalization.⁷⁰⁷ Discussion of plans for pain control and patient-controlled analgesia help to control potential anxiety. Patients with preoperative history of illegal drug use or preoperative prescription narcotics typically require higher doses of analgesia postoperatively. Inadequate analgesia can lead to decreased chest physiotherapy and ambulation.

Many adult survivors of congenital heart disease have unique alterations in neurologic status related to the presence of genetic syndromes (Down, DiGeorge, Williams) or previous neurologic alterations leading to developmental delays and increased dependence on family involvement in care. Rest and privacy are essential. The adult's bedtime ritual can be assessed. Some may use prescriptions, rituals, or over-the-counter medications to promote sleep.

Unique developmental needs and degree of family involvement may be present in the patient with ACHD. Some may rely heavily on a parent and/or significant other for making decisions and daily activities. Survivors require guidance in terms of educational and vocation choices. Some of the survivors of complex congenital heart disease management are at risk for inattention, hyperactivity, and developmental disabilities, and require remedial school services.⁷⁹⁸

Issues with independence and interdependence may exist, as well as other psychological challenges found in patients with chronic illness, as detailed in Claessens et al¹⁸⁰ and Tong et al.⁸⁶⁷ Providers should assess the patient's knowledge and independence in areas of self-care.

Systemic Vascular Resistance

Systemic vasoconstriction may be a compensatory mechanism in a low cardiac output state or from administration of vasoconstrictors. Treatment of increased afterload involves avoidance of precipitating factors, intravenous nonspecific vasodilating agents (SVR and PVR), inhaled vasodilators (PVR), and mechanical ventilator manipulation to optimize cardiopulmonary interactions (e.g., intubation and supporting ventilation for reducing left ventricular afterload).

If systemic vascular resistance (SVR) is high or even normal in the presence of ventricular dysfunction, or the child demonstrates significant peripheral vasoconstriction with poor systemic perfusion, treatment with vasodilators usually is indicated. These agents are nonspecific and may cause dilatory effects in both the systemic and pulmonary beds. When intravenous vasodilators are administered, the child's fluid volume status must be adequate because hypotension may develop, especially during initiation of therapy.

Vasodilators can reduce ventricular preload and afterload because they produce venous and arterial dilation (see Chapter 6). During vasodilator therapy, assess the warmth of the child's extremities, capillary refill, serum lactate, urine output, and blood pressure to determine the effectiveness of therapy. If multiple agents are used, it is also important that the dose of only one medication be changed at any one time so that the patient's response to each change can be determined.

Pulmonary Vascular Resistance

Pulmonary vasoconstriction can result from alveolar hypoxia, acidosis, hyperinflation of the lung, and hypothermia. In addition, cardiopulmonary bypass can affect vascular tone and permeability. Pain may also affect vascular tone.⁷³ Elevated pulmonary vascular resistance (PVR) may be a developmental, acute, or chronic condition. For example, newborns have reactive pulmonary vascular bed and are susceptible elevated PVR. Additionally, some children have a genetic predisposition for pulmonary hypertension, such as children with trisomy 21.⁶⁵² For further information, see Box 8-1 and Table 8-16.

The effects of cardiopulmonary (CPB), pulmonary leukosequestration, microemboli, and hypothermia have been implicated in pulmonary vascular endothelium dysfunction, and elevated PVR with increased pulmonary vasoreactivity in the postoperative period.^73,206,667 Excessive pulmonary blood flow and left-to-right intracardiac shunts before and after CPB, elevated pulmonary venous pressure, lung pathology, blood products, and Protamine are several of the other risk factors associated with postoperative elevation in PVR.^73,667,845 Post-CPB pulmonary endothelium dysfunction may be responsible for increased generation of pulmonary vasoconstricting mediators and decreased endogenous nitric oxide (NO) production associated with vasodilatation.^71,73

An increase in the child's pulmonary vascular resistance also may be an acute cause of inadequate systemic perfusion postoperatively. An acute rise in PVR with resulting decreased cardiac output, acidosis, hypoxemia, and increased right ventricular (RV) afterload can worsen any preexisting RV dysfunction.^4,7,73,206

Pulmonary hypertension (PHTN) is characterized by an elevation in pulmonary artery pressure and PVR. It is defined as a systolic pulmonary artery pressure (PAP) greater than 35   mm Hg or a mean PAP greater than 25   mm Hg at rest. Often in the clinical setting, the severity of PHTN is discussed in relation to systemic arterial pressures. Treatment for PHTN typically begins at approximately half systemic pressures. In the absence of a pulmonary artery catheter, it is possible to assess for effects of PVR by monitoring the systemic venous atrial or central venous filling pressures. A child experiencing PTHN will have a rising right atrial or central venous pressure, falling left atrial (or pulmonary venous atrial) pressure, and falling blood pressure.

PHTN can lead to RV failure, low cardiac output state, impaired oxygen delivery, and shock. The goals of care are to decrease PVR and maximize RV function, and optimize cardiac output.⁶⁵² Support of right ventricular function and output is important. Milrinone, dopamine, or epinephrine may be used to support cardiac output. Optimizing right ventricular preload can improve cardiac output, because elevated right atrial pressures are required to maintain adequate ventricular filling.⁸⁴⁵

The child with perioperative pulmonary hypertension requires precise postoperative ventilator management and must remain well oxygenated and ventilated, as well as warm. Providers should make an effort to treat pain and agitation and minimize stimulation (see section, Common Clinical Conditions, Pulmonary Hypertension). Respiratory mechanisms to lower PVR include ensuring adequate gas exchange, maintaining functional residual capacity, and avoiding hypoinflation or hyperinflation. Alveolar hypoxia, such as may be produced by hypoventilation, pneumothorax, airway obstruction, suctioning, and atelectasis, must be avoided. A mild alkalosis will promote pulmonary vasodilation. These children usually require mechanical ventilator support for several days, and then gradual weaning is attempted. During weaning the child's pulmonary pressure (if available) and systemic perfusion should be monitored carefully because hypoventilation produces alveolar hypoxia and can result in pulmonary vasoconstriction.

These children may also require blunting of stress responses with opioid or benzodiazepines, and ventilation with sedation and neuromuscular blockade may be needed. There may be benefit to premedicating the child with an opioid and/or benzodiazepine before suctioning or noxious stimuli to blunt responses to the stimulus. Clustering care to prevent excessive stimulation may reduce the potential for PHTN crisis as well.

Prevention or prompt correction of acidosis is required with either respiratory or metabolic maneuvers to achieve a pH of approximately 7.5.⁶⁵² Pulmonary vasodilatation with specific and nonspecific agents is frequently accomplished through administration of inhaled nitric oxide (specific) and/or milrinone (nonspecific). If inhaled nitric oxide is administered it should be weaned slowly to avoid rebound effect. Weaning from any PVR therapy should be accomplished in a stepwise, methodical fashion.⁸⁴⁵

Endotracheal suctioning is a well-known noxious stimulus that can provoke PHTN. Hyperventilation and hyperoxygenation have been shown to reduce suctioning induced hypoxia.⁶⁶⁹ The use of in-line suctioning catheters may be beneficial as well.⁴⁴² If open suctioning is required, two nurses should perform the procedure. The first nurse provides hand or mechanical ventilation and maintains oxygenation. If inhaled nitric oxide is being used, ensure that there is delivery of the drug into the hand ventilation circuit. The second nurse provides skilled, gentle suctioning. Children with extremely labile pulmonary vascular beds should have a physician or advanced practice nurse present during suctioning. Please refer to Common Clinical Conditions, Pulmonary Hypertension for further information.