Physical Examination

A complete physical examination in a patient with previously repaired CHD will often yield information critical to the proper planning of a general surgical procedure. Patients need to be completely undressed and thoroughly examined. In many cyanotic patients, color changes may be prominent, particularly in the nail beds, lips, and mucous membranes. In other patients, cyanosis may be subtler, giving the patient a gray or even pale appearance. Previous surgical incisions need to be noted and reconciled with the known medical history. Thoracotomy incisions on either side may indicate a previous BT shunt using the turned-down, divided subclavian artery or with a prosthetic interposition graft, the so-called modified BT shunt. In patients with a left aortic arch, a left thoracotomy incision will be present if a previous coarctation repair has been carried out. Median sternotomy incisions or anterior thoracotomy incisions may indicate previous intracardiac or extracardiac surgery.

A complete vascular examination is often overlooked in patients with CHD. It is important to assess pulses and obtain blood pressure measurements in all four extremities. Patients who have an existing or have previously had a BT shunt often have diminished or absent pulses in the upper extremity corresponding to the previous shunt. This may also be true in the left upper extremity in patients with previous coarctation repairs, especially if a subclavian flap angioplasty was performed (Waldhausen procedure). Furthermore, a history of previous coarctation repair does not guarantee that the lower extremity pulses and blood pressures will be normal. Also, patients who have undergone previous cardiac catheterization may have chronically stenosed or occluded femoral vessels. All these issues may be of significance for monitoring and vascular access in a patient undergoing a general surgical procedure.

Later in this chapter, the Fontan procedure for single-ventricle palliation will be reviewed. Briefly, this operation results in significant systemic venous hypertension, often in the range of 12 to 15 mm Hg. In patients with a Fontan circulation, physical examination may reveal hepatic congestion, ascites, pedal edema, venous varicosities, and jugular venous distention. In some individuals, macronodular hepatic cirrhosis may be suspected on the basis of a firm fibrotic liver edge.

Entire textbooks have been dedicated to the physical examination of patients with cardiac disease and a thorough discussion of this issue, particularly the specifics of cardiac auscultation, is beyond our scope here. In general, however, the cardiac examination includes an assessment of the patient’s rhythm, point of maximal impulse, and character of any auscultated murmurs. It must also be emphasized that the absence of a significant cardiac murmur does not rule out significant cardiac pathology.

Diagnostic Tests

Plain Radiography

Standard chest radiography with anteroposterior and lateral views is still an essential component of the assessment of a patient with CHD. Standard elements to be examined include a skeletal survey, assessment of the diaphragms and hepatic shadow, and location of the gastric bubble. The lung fields are assessed for pulmonary plethora (arterial or venous), air space disease, and presence of effusions. The cardiac silhouette may reveal much important information, such as a cardiothoracic ratio indicative of cardiomegaly or pericardial effusion, presence of atrial enlargement, presence or absence of the pulmonary artery shadow, and arch sidedness (Fig. 59-4).

FIGURE 59-4 Cardiomegaly and increased pulmonary vascular markings in a patient with complete atrioventricular canal defect.

Cardiac Catheterization

Cardiac catheterization has long been considered the gold standard for diagnostic imaging of congenitally malformed hearts. With the current sophistication of echocardiography, this is no longer the case for most patients. Nonetheless, there are still circumstances in which diagnostic cardiac catheterization is necessary to obtain accurate anatomic detail. This may true for patients who have poor echocardiographic windows, although even this issue may be overcome using transesophageal echocardiography. More often, there are specifics of anatomic detail that neither echocardiography nor MRI can delineate, such as branch pulmonary artery (or segmental) stenoses, origin and course of aortopulmonary collateral vessels, and fistulous connections and intracardiac communications (septal defects) not clarified by other imaging modalities.

Usually, however, diagnostic cardiac catheterization is performed to obtain precise hemodynamic information needed to make an informed assessment of the consequences of the patient’s cardiac lesions. Using oximetric measurements, pressure data, and thermodilution cardiac output determination, accurate assessment of the patient’s hemodynamic profile is obtained. Measured or derived data include central venous pressure, atrial pressure, ventricular pressures (including end-diastolic pressure), shunt fraction (in the case of atrial or VSDs), pulmonary artery pressures, pulmonary capillary wedge pressure, systemic arterial pressure, and segmental oximetry of cardiac structures, including systemic and pulmonary venous return (Fig. 59-5). Thus, critical information is obtained about the presence and degree of shunting, systemic and pulmonary vascular resistance, and cardiopulmonary function. In certain clinical settings, these data are mandatory to a successful clinical management strategy. This may be particularly true for the adult patient with congenital cardiac disease requiring noncardiac surgery.

FIGURE 59-5 Hemodynamic information obtained following cardiac catheterization.

A thorough understanding of normal cardiorespiratory physiology is critical in interpreting data obtained by cardiac catheterization in the patient with CHD. Specifically, the normal pressure range, pulse waveforms, and oxygen saturations for the various cardiac chambers must be compared against data obtained in a deranged circulation. The various cardiac chambers have normal pulse waveforms. In the atria, there are characteristic waveforms—a wave corresponding to atrial contraction, c wave corresponding to atrioventricular valve closure, and v wave corresponding to atrial filling from venous return against the closed atrioventricular valve. Typical normal right atrial mean pressures range from 1 to 5 mm Hg and left atrial pressures range from 2 to 10 mm Hg. Right ventricular pressure tracings in normal hearts demonstrate a more gradual upstroke when compared with the left ventricle. Filling or end-diastolic pressures range between 2 and 10 mm Hg in normal hearts. The normal right ventricular systolic pressure ranges from 15 to 30 mm Hg (and thus pulmonary artery systolic pressure) and the left ventricular systolic pressure ranges from 90 to 110 mm Hg.

In normal hearts, there is a small, physiologically insignificant right-to-left shunt, which results from ventilation-perfusion mismatch in the lungs and coronary venous return directly to the left ventricle (thebesian venous return). This physiologic shunt represents less than 5% of the cardiac output and, in normal circumstances, does not produce detectable systemic arterial desaturation. Thus, significant systemic arterial desaturation represents a pathologic finding, consistent with pulmonary disease, intracardiac shunting, or both. As noted, the origin and degree of intracardiac shunting may be assessed by echo study. In certain circumstances, however, cardiac catheterization is necessary to measure cardiac oximetry, calculate shunt fraction, and derive systemic and pulmonary vascular resistance. Using a derivation of the Fick principle, the ratio of pulmonary blood flow (Qp) to systemic blood flow (Qs) flow can be determined as follows:

where SaO₂ sat is systemic arterial oxygen saturation, sat is mixed venous oxygen saturation, sat is pulmonary venous oxygen saturation, and PaO₂ sat is pulmonary arterial oxygen saturation.

Thus, in a patient with sat of 60%, sat of 100%, Sao₂ sat of 100%, and PaO₂ sat of 80%,

Calculating vascular resistances may also be extremely important in determining operability in the patient with CHD. In many settings, a precise measure of vascular resistance is unnecessary based on the clinical evidence. For example, in the small child with a large VSD seen on the echocardiogram, the clinical findings of tachypnea, cardiomegaly, and failure to thrive confirm a large left-to-right shunt and thereby infer acceptable pulmonary vascular resistance. In less clear circumstances, however, a precise calculation may be important in clinical decision making. The pulmonary vascular resistance may be calculated from cardiac catheterization data as follows:

In general, patients with an elevated Rp are further evaluated with pulmonary vasodilation—hyperventilation, hyperoxygenation, and inhaled nitric oxide—to determine whether the resistance is responsive. This information may be critical for patients who are otherwise marginal candidates.

Finally, it must be mentioned that cardiac catheterization has been evolving as the primary therapeutic method for a number of important structural cardiac defects. In many children’s hospitals, including Texas Children’s Hospital, most catheterizations now performed are for interventional procedures rather than diagnostic. This may be particularly pertinent to the general surgeon faced with treating a patient with a previous catheter-based correction of a cardiac defect. For example, the patient may have had an atrial or VSD closed with an occluder device in the past. This information may have important ramifications for infectious exposure and vascular access.

Persistent Arterial Duct (Patent Ductus Arteriosus)

A persistent arterial duct or PDA is a frequently encountered congenital cardiac condition. The arterial duct is necessary during gestation to shunt right ventricular blood away from the unventilated pulmonary vasculature; ductal flow is from the pulmonary artery to the aorta during gestation. At delivery, after the first breath of the neonate, ductal flow reverses and becomes left to right in most individuals. Over the first several hours or days of postnatal life, the PDA closes spontaneously and is completely closed in most infants by 2 to 3 weeks of life.

In the absence of other congenital cardiac lesions—although a PDA may be present in association with other structural cardiac conditions and may sometimes be necessary for systemic or pulmonary blood flow—a PDA becomes pathologic related to its presence and degree of left-to-right shunting. The amount of shunting produced relates to the size and geometry of the duct and the pulmonary vascular resistance. A PDA may be responsible for a large Qp/Qs and result in pulmonary overcirculation, left heart volume overload, and congestive heart failure (CHF). A large unrestricted PDA will be associated with pulmonary hypertension; if left untreated, this will proceed to irreversible pulmonary vascular disease (Eisenmenger’s syndrome), ultimately proceeding to pulmonary and right heart failure, only treatable by pulmonary transplantation. Even with a small, pressure-restrictive PDA, there is an ongoing risk for pulmonary congestion and left heart volume overloading; endocarditis is always of concern for even small PDAs. As such, closure is recommended for all PDAs.

The gold standard of therapy for closure of PDA is surgery, usually accomplished through a left thoracotomy using ductal division, ligation, or clipping (Fig. 59-6). This needs to be a low-risk procedure associated with minimal potential for persistence. Nonetheless, the invasive nature of this proven method has led to the development of alternative strategies for ductal occlusion. From a surgical perspective, many PDAs are amenable to thoracoscopic clipping through very small port incisions; robot-assisted PDA occlusion has been performed in many patients, with good results.¹² At present, however, most PDAs are occluded in the cardiac catheterization laboratory using occlusive devices. Even the repair of large defects in small babies has been successfully addressed. The long-term effects of the devices remaining in the vascular tree are as of yet not fully understood; however, successful device closure appears to be an extremely effective and durable therapy.¹³

FIGURE 59-6 Anatomic relationships of a patent ductus arteriosus, exposed from a left thoracotomy.

(From Castaneda AR, Jones RA, Mayer JE Jr, Hanley FL: Patent ductus arteriosus. In Castaneda AR, Jones RA, Mayer JE Jr, Hanley FL: Cardiac surgery of the neonate and infant, Philadelphia, 1994, WB Saunders.)

A PDA in an adult patient can be challenging. As noted, a long-standing large PDA may be associated with pulmonary vascular disease. Clearly, a right-to-left shunt in a PDA is cause for significant concern and warrants further investigation. In adults with PDAs, the arterial wall may calcify, making an attempt at ligation or division hazardous. In these patients, ductal occlusion may require resection of the adjacent descending aorta with patch grafting or short-segment graft replacement (Dacron).

Aortopulmonary Septal Defect (Aortopulmonary Window)

An aortopulmonary septal defect is a communication between the ascending aorta and, usually, the main pulmonary artery. This is a rare defect; it relates to the common embryologic origin of the arterial trunk and failure of complete separation into the aorta and pulmonary artery. Defects are classified by their location: type I is proximal, just above the aortic sinuses; type II is more distal on the ascending aorta and often involves the origin of the right pulmonary artery; and type III is more distal and associated with a separate origin of the right pulmonary artery from the aorta (Fig. 59-7). An aortopulmonary septal defect may occur in isolation or in association with other conditions, including interrupted aortic arch (IAA) and anomalous origin of a coronary artery. Defects are typically large and responsible for a large left-to-right shunt with systemic pulmonary artery pressures. Children with this problem typically present with CHF, failure to thrive, and frequent respiratory infections. Diagnosis may be made by echocardiography, MRI, or catheterization.

FIGURE 59-7 Native anatomy and classification of aortopulmonary septal defect. A, In type I, the communication is between the ascending aorta (Ao) and the main pulmonary artery (PA) on the posterior medial wall of the ascending aorta. The left main coronary artery (LCA) orifice may be close to the defect. B, In type II, the defect is more cephalad on the ascending aorta. C, In type III, the defect is more posterior and lateral in the aorta. The communication is with the right pulmonary artery, which may be completely separate from the main pulmonary artery.

(Adapted from Fraser CD: Aortopulmonary septal defects and patent ductus arteriosus. In Nichols DG, Ungerleider RM, Spevak PJ, et al [eds]: Critical heart disease in infants and children, Philadelphia, 2006, Mosby, pp 664–666.)

All aortopulmonary septal defects are surgically closed; this lesion is not amenable to catheter-based closure and such an attempt is hazardous. A small defect may be ligated through a thoracotomy or median sternotomy approach, but this method is not recommended because of significant risk for rupture or incomplete closure. Surgical closure is accomplished with cardiopulmonary bypass support. Options for closure include complete division and separate patch repairs of the great vessel defects or a sandwich type of closure, using a patch to construct a common intervening wall; both methods are effective (Fig. 59-8).

FIGURE 59-8 A, Surgical exposure of aortopulmonary (AP) septal defect includes a transverse incision in the ascending aorta (Ao). B, Aortopulmonary septal defect is closed by suturing a patch over the aortic side of the defect. PA, Pulmonary artery.

(Adapted from Fraser CD: Aortopulmonary septal defects and patent ductus arteriosus. In Nichols DG, Ungerleider RM, Spevak PJ, et al [eds]: Critical heart disease in infants and children, Philadelphia, 2006, Mosby, pp 664–666.)

Atrial Septal Defect

An isolated atrial septal defect (ASD) is one of the most common congenital cardiac lesions. The most frequently encountered ASD relates to a defect in the interatrial wall, as defined by the fossa ovalis. The defect develops as the result of incomplete closure of the embryologic patent foramen ovale; thus, the defect is a result of incomplete closure of the septum primum. Although the terminology can be confusing, these defects are typically termed secundum atrial septal defects. They present in a wide variety of configurations, ranging from single small defects to multiple fenestrations to complete absence of the septum primum. The confines of the defect may extend from the IVC orifice up to the superior atrial wall adjacent to the aortic root (Fig. 59-9).

FIGURE 59-9 Types of atrial septal defects as viewed through the right atrium—ostium secundum, ostium primum, and sinus venosus.

(Adapted from Redmond JM, Lodge AJ: Atrial septal defects and ventricular septal defects. In Nichols DG, Ungerleider RM, Spevak PJ, et al [eds]: Critical heart disease in infants and children, Philadelphia, 2006, Mosby, p 580.)

The primary pathophysiologic derangement in ASDs relates to a significant left-to-right shunt in the setting of normal pulmonary vascular resistance. It must be emphasized, however, that even in the setting of a normal Rp, patients with ASDs are capable of transient right-to-left shunting, particularly during times of increased intrathoracic pressure. The effects of chronic, large left-to-right shunting (in some patients producing a Qp/Qs >3 : 1) include right heart volume overloading and enlargement. Most children are not overtly symptomatic but may exhibit some degree of exercise intolerance or frequent respiratory tract infection. Symptoms typically become more prevalent in adulthood and include dyspnea on exertion, palpitations and, ultimately, evidence of right heart failure. Pulmonary vascular disease is not a typical finding in secundum ASDs, but one may demonstrate an ASD in a patient with primary pulmonary hypertension. A rare form of presentation relates to the potential of right-to-left shunting at the atrial level; the ever-present risk for paradoxical embolus and cerebrovascular accident must be considered when recommending ASD closure.

Most centers recommend ASD closure before school age. The standard therapy for ASDs since the late 1950s has been surgical closure using cardiopulmonary bypass support. The defect is closed using direct suture closure, autologous pericardium, or prosthetic patch material (Fig. 59-10). This is an effective method, with a low associated perioperative risk, including the virtual absence of residual or recurrent defects, as noted in one study.¹⁴ Minimally invasive techniques for ASD closure have also gained popularity.

FIGURE 59-10 Surgical closure for atrial septal defect. A, Right atriotomy. B, Direct suture closure. C, Patch closure. D, Deairing the left atrium (LA). Ao, Aorta; CS, coronary sinus; PA, pulmonary artery; TV, tricuspid valve.

(Adapted from Redmond JM, Lodge AJ: Atrial septal defects and ventricular septal defects. In Nichols DG, Ungerleider RM, Spevak PJ, et al [eds]: Critical heart disease in infants and children, Philadelphia, 2006, Mosby, p 583.)

The potential for closing defects using nonsurgical methods has led to the development of catheter-based therapies, which are now being widely applied to large numbers of patients worldwide for the treatment of ASD. The most commonly used device is the Amplatzer septal occluder (St. Jude Medical, St. Paul, Minn) device, of nitinol metal mesh, which is placed percutaneously and delivered with echocardiographic and fluoroscopic guidance. Early reports have indicated an acceptable procedure-related complication rate and successful closure rate.¹⁵ It is clear, however, that the long-term effects of having such a device in mobile cardiac structures are not fully understood. Several recent reports have documented an alarming incidence of device erosion through the atrial wall and into the adjacent ascending aorta, as well as disruption of the conduction system.^16,17 A recent case of late severe endocarditis involving a previously placed Amplatzer ASD device has highlighted the need for ongoing observation of the long-term consequences of placing large prosthetic devices into the circulation.¹⁸

Sinus venosus atrial septal defects occur as the result of embryologic malalignment between the superior vena cava (SVC) or IVC. These defects are not associated with the ovale fossa and are frequently associated with partial anomalous pulmonary venous return. A superior sinus venosus ASD occurs high in the atrium, near the orifice of the SVC. This lesion is frequently associated with anomalous drainage of a portion of the right lung to the SVC. An inferior sinus venosus ASD is located low in the atrium, often extending into the IVC orifice. This lesion is typically associated with anomalous pulmonary venous drainage of the entire right lung to the IVC (potentially intrahepatic); pulmonary sequestration and an abnormal systemic artery perfusing the right lower lobe, with origin from the abdominal aorta, may also be present. In patients with total anomalous pulmonary venous return (TAPVR) to the IVC, the anomalous pulmonary vein may be readily obvious on a plain chest radiograph and has been described as appearing like a saber (scimitar syndrome), first described by Sabiston and Neill.¹⁹

Surgery for sinus venosus ASDs is recommended for the same pathophysiologic reasons as secundum ASDs. The repair is not amenable to catheter techniques, and surgery is more complicated than for an isolated secundum ASD. Superior sinus venosus defects with partial anomalous pulmonary venous return to the SVC may be treated with an intracardiac patch baffle; however, in the setting of high drainage of the anomalous pulmonary veins, an SVC translocation operation (Warden procedure) may be necessary.²⁰ Surgery for an inferior sinus venosus ASD with a scimitar vein can be more complicated, potentially involving the need for a patch baffle within the intrahepatic IVC, which may require periods of hypothermic circulatory arrest.

Perimembranous Ventricular Septal Defect

A perimembranous VSD occurs as a defect in the membranous portion of the interventricular septum; its associated margins include the annulus of the tricuspid valve, the muscular septum, and potentially the aortic annulus. The defects may be large and have associated prolapse of the noncoronary or right coronary aortic valve cusps. Perimembranous VSDs exhibit a potential for spontaneous closure, particularly small defects presenting early in childhood.

Muscular Ventricular Septal Defect

Muscular VSDs occur in all aspects of the muscular interventricular septum. Margins of these defects are entirely muscle. The lesions may be isolated or involve multiple openings in the septum (so-called Swiss cheese septum). Small defects have great potential for regression or spontaneous closure.

Subarterial (Supracristal or Outlet) Ventricular Septal Defect

Subarterial VSDs occur in association with the annulus of the aortic valve, pulmonary valve, or both. The defects are almost always associated with significant prolapse of the adjacent aortic valve cusp, usually the right coronary cusp, which may lead to significant cusp distortion, aortic valve insufficiency, and even cusp perforation. The only mechanism for spontaneous closure of these defects relates to the cusp prolapse and valve distortion and is generally not complete or a favorable arrangement. All these defects are surgically closed because of the ongoing risk for aortic valve injury (Fig. 59-11).

FIGURE 59-11 Location of VSDs in the ventricular septum (view of the ventricular septum from the right side). 1, Perimembranous VSD; 2, subarterial VSD; 3, atrioventricular canal–type VSD; 4, muscular VSD.

(From Tchervenkov CI, Shum-Tim D: Ventricular septal defect. In Baue AE, Geha AS, Hammond GL [eds]: Glenn’s thoracic and cardiovascular surgery, ed 6, Stamford, Conn, 1996, Appleton & Lange.)

The indications for surgery to close VSDs relate to the size of the VSD, degree of shunting, and associated lesions. Thus, small babies presenting with large VSDs, refractory heart failure, and large shunts undergo surgical closure of the defects in the newborn period, irrespective of age or size. Other defects are addressed based on the ongoing concerns of left-to-right shunting, aortic valve cusp distortion, and risk for endocarditis. Asymptomatic patients with evidence of significant shunts and cardiomegaly are proposed for surgical therapy. Prophylactic closure of small defects in asymptomatic patients with normal cardiac size and function is advocated by some surgeons because of the lifelong risk for endocarditis and comparatively low risk for surgery.

Although catheter-based therapies for some VSDs have been developed, particularly muscular defects, this mode of therapy is still not widely applicable to most VSDs.²¹ The complex relationship of many defects, including close association with the aortic valve and cardiac conduction tissue, makes the existing technology less than ideal. At present, surgery remains the primary mode of therapy for VSD closure. Defects are approached with the aid of cardiopulmonary bypass support and may be closed with various materials, including autologous pericardium (our preference), Dacron, polytetrafluoroethylene (PTFE), and homograft material. Surgical closure of VSDs is a low-risk procedure with a high expectation of complete closure.²² Challenging anatomic situations such as Swiss cheese septum or multiple apical muscular VSDs may be initially palliated by limiting pulmonary blood flow with a pulmonary artery band and deferring corrective surgery to later in life.

Adult Patient With Atrioventricular Septal Defect

A number of patients with partial or transitional AVSD survive well into adulthood without surgery. These patients have variable modes of presentation but may exhibit severe exercise intolerance, evidence of right heart dysfunction, some elevation of pulmonary vascular resistance and, possibly, atrial dysrhythmias, including atrial fibrillation. In such late-presenting patients, cardiac catheterization is often recommended to rule out occult coronary artery lesions and evaluate pulmonary vascular resistance. Nonetheless, in the absence of obvious surgical contraindication, surgery is recommended for adults with unrepaired AVSD to eliminate the chronic left-to-right shunt and repair the typically insufficient atrioventricular valves.

Other patients are now presenting well into adulthood with previously repaired AVSDs. These patients may have a widely disparate constellation of findings, including atrial and ventricular dysrhythmias, valvular insufficiency or stenosis, and right heart dysfunction. In many of them, secondary reparative surgery may become necessary. Furthermore, in the setting of a patient with remotely repaired AVSD requiring noncardiac surgery, it must be expected that there are potential ongoing hemodynamic concerns that will affect the perioperative course.