LAW No. 167 of 16 JULY 1997 OF THE REPUBLIC OF KAZAKHSTAN THE CRIMINAL CODE OF THE REPUBLIC OF KAZAKHSTAN 3 page

PATENT DUCTUS ARTERIOSUS

PATENT DUCTUS ARTERIOSUS. A small patent ductus arteriosus is of little or no physiological significance, and there are no postoperative limitations after division of an isolated restrictive patent ductus. Recommendations after division of a moderately restrictive or nonrestrictive patent ductus with large left-to-right shunt and variable elevations of pulmonary arterial pressure depend upon the guidelines just set forth for postoperative moderately restrictive to nonrestrictive ventricular septal defect.

Pulmonary vascular disease in these cyanotic patients is a contraindication to strenuous exercise. In patients with suprasystemic pulmonary vascular resistance and right-to-left shunts, even low levels of isotonic exercise tend to be accompanied by decrements in systemic arterial oxygen content and the development of tissue lactic acidosis. The exercise-induced increase in right-to-left shunt poses a special problem regarding the elimination of metabolically produced carbon dioxide, resulting in high ventilatory requirements, subjective dyspnea (Fig. 30–13 Fig. 30–13 ), and occasionally, respiratory acidosis.150,151 In nonrestrictive patent ductus arteriosus with suprasystemic pulmonary vascular resistance and reversed shunt, exercise may cause leg fatigue but comparatively little dyspnea, because the ventilatory stimuli of hypoxemia, hypercapnia, and acidemia circumvent the respiratory center. (Venous blood is delivered to the lower body but not to the vital centers of the head and neck.5)

FALLOT’S TETRALOGY

FALLOT’S TETRALOGY. In patients with this anomaly isotonic exercise provokes a fall in systemic vascular resistance and an augmentation of venous return to a right ventricle with fixed obstruction to outflow, so the right-to-left shunt increases. The subjective sensation of breathlessness is caused chiefly by the response of the respiratory center to the sudden change and blood gas composition and pH as just described. The relief of effort-induced dyspnea by squatting (see [For More Information] ), a time-honored hallmark of Fallot’s tetralogy in children, is seldom seen in adults.5 Squatting exerts its salutary effect by countering the exercise-induced fall in systemic vascular resistance and by decreasing the amount of low oxygen content inferior vena caval blood that is received by the right ventricle and shunted into the aorta during exercise. High-intensity isometric exercise in Fallot’s tetralogy abruptly reduces flow from the right ventricle into the aorta in the face of fixed obstruction to right ventricular outflow, so systemic flow suddenly falls, risking syncope and occasionally sudden death. All but low-intensity isometric exercise is proscribed.

After repair of Fallot’s tetralogy, recommendations regarding physical activity and participation in athletics depend upon patient age at operation and the presence and degree of postoperative residua and sequelae.183 After repair of Fallot’s tetralogy, patients should undergo two-dimensional echocardiography with Doppler interrogation and color flow imaging, exercise stress testing, and 24-hour ambulatory electrocardiography. If obstruction to right ventricular outflow is mild or absent, if the shunt is absent or trivial, if low-pressure pulmonary regurgitation is no more than mild to moderate, if there are no significant disturbances in ventricular rhythm, and if right ventricular size and function are normal or nearly so, limitations are not imposed upon athletic activity, either isotonic or isometric.183 Of particular concern are residual right ventricular outflow gradients that increase significantly during exercise and are accompanied by right ventricular ectopic rhythms believed to originate at the site of the ventriculotomy scar. Postoperative bifascicular block (Fig. 30–17 Fig. 30–17 ) is uncommon with current surgical techniques. Bifascicular block without the aforementioned residua or sequelae does not in itself preclude unrestricted physical activity, provided that the 24-hour ambulatory ECG records no additional evidence of impaired atrioventricular conduction.

COMPLETE TRANSPOSITION OF THE GREAT ARTERIES

COMPLETE TRANSPOSITION OF THE GREAT ARTERIES. Data regarding this anomaly are derived chiefly from patients who have undergone atrial switch operations in early life. With few exceptions, important postoperative residua and sequelae require that isotonic physical activity be restricted to mild or moderate intensity and limited duration. Recommendations regarding athletic activity after the arterial switch operation cannot currently be made. However, there is an air of cautious optimism that uncomplicated arterial switch repairs may circumvent the electrophysiological sequelae so common after atrial switch operations (Fig. 30–11 Fig. 30–11 ), while allowing the morphological left ventricle to serve as the systemic pump.

The Fontan operation permits study of the human circulation in which total right atrial or total caval flow is channeled directly into the pulmonary artery or into a small right ventricle that serves only as a conduit. Exercise performance improves but remains subnormal and the cardiac index increases, but seldom more than twofold.132a,168,184 Patients with optimal repairs are permitted moderate-intensity isotonic exercise if the following criteria are met: (1) a satisfactory working capacity as judged by exercise stress testing, (2) stable sinus rhythm with no significant disturbances in atrial or ventricular rhythm in response to exercise or on 24-hour ambulatory electrocardiography, (3) normal ventricular function as determined by two-dimensional echocardiography or radionuclide imaging, and (4) normal systemic arterial oxygen saturation.

Employability and Psychosocial Considerations

EMPLOYABILITY

EMPLOYABILITY. Opportunities for employment of adults with congenital heart defects are influenced by the type of cardiac lesion, cardiac surgery, job discrimination, and educational level.185 Legislation has been enacted to protect the rights of patients and to provide assistance in seeking employment. Overprotective attitudes of parents and teachers combined with absence of self-discipline may seriously reduce competitive spirit and curtail educational achievement. Job discrimination is one of the most important factors affecting employment opportunities for patients with congenital heart disease. The smaller the company, the greater the reluctance to hire an employee with a thoracotomy scar or with preexisting cardiac disease.

In selected occupations (bus drivers and airline pilots, for example), the safety of others is in the hands of a single individual. To make sensible recommendations regarding fitness for these occupations, the patient’s risk of incapacity or sudden death must be defined. The National Rehabilitation Act of 1973 and the Vocational Rehabilitation Act of 1920 offer a wide range of services that are significantly underutilized, especially by cardiac patients.

PSYCHOSOCIAL CONSIDERATIONS

PSYCHOSOCIAL CONSIDERATIONS. Special if not unique psychological problems confront patients who have experienced dramatic and sometimes traumatic diagnostic and therapeutic interventions during key developmental phases of their lives.186 The trend toward early diagnosis and reparative surgery in congenital heart disease has made it difficult to generalize from results of studies done 10 to 20 years ago. Despite methodological difficulties and a number of constraints, a reasonable understanding has been achieved by critical assessment of available data combined with clinical experience.

Most patients with congenital heart disease function within normal psychological range, although low self-esteem, insecurity, and feeling of vulnerability are matters of concern.186 Parental knowledge, understanding, and attitude significantly affect psychosocial adjustments. Difficulty in accepting illness may be manifested by denial and by potentially self-destructive behavior, especially in adolescents. Adults with congenital heart disease face problems in the workplace, in dating, in marriage, and in parenthood. Cyanosis impairs intellectual function, although the degree of impairment is generally mild and often overestimated by IQ tests that depend upon gross motor function at a young age. Early surgery in cyanotic patients appears to improve intellectual and psychological development.187 Circulatory arrest with deep hypothermia may have subtle adverse effects upon intellectual function, especially if the circulatory arrest and hypothermia are prolonged.188

Surgical Considerations

Operation or reoperation for adults with congenital heart disease involves special surgical considerations peculiar to an older patient population.2 When preoperative phlebotomy is required to improve hemostasis in cyanotic patients, the blood should be stored for potential autologous transfusion. Reoperation after palliative procedures involves revision of Blalock-Taussig shunts, Glenn shunts, Potts or Waterston shunts, and pulmonary arterial bands. Important considerations at reoperation after reparative surgery are reconstruction of cardiac valves and replacement of conduits or prosthetic valves. Operative planning requires knowledge of the basic congenital malformation, of the initial surgical procedure, and of postoperative residua, sequelae, and complications. Perhaps the most important variable that precludes reparative or palliative surgery or reoperation is pulmonary vascular disease. Depressed ventricular function, which is the second major impediment to operability or reoperability, is a consequence of volume or pressure overload, myocardial ischemia, and inherent ventricular morphology.

Certain important principles apply intraoperatively, including myocardial protection, cardioplegia, and hypothermia. Intraoperative salvage of red blood cells and platelet-rich plasma before cardiopulmonary bypass has diminished the need for nonautologous blood and blood products. Minimizing the need for donor blood and blood products is more important at reoperation because of the greater risk of bleeding. The sternotomy incision at reoperation is a technical problem, posing a significant risk when an enlarged right ventricle is apposed to the sternum and when right ventricular outflow conduits adhere. The risk can be reduced materially if reoperation is anticipated at the time of initial repair with placement of an anterior patch of synthetic pericardium.

There are three categories of prostheses: patches, valves, and conduits. The devices and materials selected must achieve an immediately successful technical result, while taking into account the long-term postoperative effects on morbidity and mortality. The choice of materials is based on the patient’s age and size, the nature of the congenital malformation, the type of repair, whether or not subsequent repairs are anticipated, the availability of various synthetic and biological materials and devices, complications of long-term anticoagulation, and the risk of infection.

Cardiac Catheterization as a Therapeutic Intervention

(See also Chap. 39 )

Therapeutic cardiac catheterization, like cardiac surgery, has three principal objectives: (1) preservation or improvement of cardiac function, (2) an increase in longevity, and (3) maintenance or improvement of the quality of life. When the catheterization technique achieves these ends, surgical morbidity and mortality are circumvented. Corrective or reparative interventional catheterization procedures currently apply to pulmonary valve stenosis (Fig. 30–9 Fig. 30–9 ), recoarctation of the aorta, patent ductus arteriosus, and selected patients with atrial septal defect. Palliative interventions can be either in lieu of surgery or as adjuncts to surgery. Procedures performed in lieu of surgery apply to lesions such as aortic valve stenosis (Fig. 30–10 Fig. 30–10 ), postoperative systemic or pulmonary venous obstruction, native coarctation of the aorta, obstructed bioprosthetic valves, and pulmonary arteriovenous fistulas (Fig. 30–8 Fig. 30–8 ). Palliative procedures that are adjuncts to surgery deal with systemic-to-pulmonary arterial collaterals, systemic-to-pulmonary arterial surgical shunts, pulmonary or systemic venous obstruction, certain intraatrial communications, and selected patients with pulmonary artery stenosis.

Noncardiac Surgery in Adults with Congenital Heart Disease

(See also Chap. 54 )

When adults with congenital heart disease require noncardiac surgery, perioperative risks can be reduced, often appreciably, if problems inherent in that patient population are anticipated.2,155 The following discussion includes patients with cyanotic or acyanotic congenital heart disease who have not undergone cardiac surgery, and patients who have undergone reparative cardiac surgery.

SITUS INVERSUS WITH DEXTROCARDIA

SITUS INVERSUS WITH DEXTROCARDIA (see [For More Information] ). This cardiac malposition may go unrecognized until an illness that requires noncardiac surgery brings the adult to medical attention.5 Accompanying symptoms are likely to be misconstrued and diagnostic conclusions incorrect unless the mirror-image visceral positions are known. In acute appendicitis, the abdominal pain is in the left lower quadrant, whereas biliary colic is in the left upper quadrant. The risk of noncardiac surgery is the same in the presence of situs inversus as in patients with normal situs, provided no congenital malformations coexist in the mirror-image heart.

CONGENITAL COMPLETE HEART BLOCK

CONGENITAL COMPLETE HEART BLOCK (see [For More Information] ). This conduction defect requires electrocardiographic monitoring during and immediately after noncardiac surgery. Intraoperative vagotonic stimuli during ophthalmic or gastrointestinal surgery should be minimized and treated with intravenous atropine expectantly or if there is a sudden decrease in heart rate.155 If the preoperative scalar ECG shows wide QRS complexes and a relatively slow ventricular rate, especially if there is a history of syncope or near syncope, a temporary right ventricular pacemaker should be inserted.

BICUSPID AORTIC VALVE

BICUSPID AORTIC VALVE (see [For More Information] ). If the valve is functionally normal, or nearly normal, noncardiac surgery incurs nothing more than the risk of infective endocarditis. When emergency noncardiac surgery is required in an adult with severe calcific bicuspid aortic stenosis and marginal left ventricular function, hemodynamic monitoring with a flotation catheter should be used. If surgery is elective, consideration should be given to preemptive aortic valve replacement. Balloon valvuloplasty is problematic, even more so if stenosis is due to calcification of a congenitally bicuspid aortic valve rather than to calcification of a trileaflet aortic valve. Coronary angiography may shed light on whether or not angina pectoris is caused by coexisting coronary artery disease or by augmented oxygen demands of the afterloaded left ventricle. The margin of safety during noncardiac surgery is sometimes improved by preoperative coronary angioplasty. Intraoperative monitoring of systemic blood pressure is important because a sudden fall in systemic vascular resistance may not be associated with an adequate increase in stroke volume, owing to fixed obstruction to left ventricular outflow. An attempt to correct hypotension with rapid infusion of intravenous fluids may cause pulmonary edema.155 Pharmacological support of systemic resistance is safer than an intravenous infusion and just as efficacious.

Patients with hemodynamically significant bicuspid aortic regurgitation confront noncardiac surgery with risks determined by left ventricular function and susceptibility to infective endocarditis. If ventricular function is normal, the risk of noncardiac surgery is small. Moderate intraoperative anesthetic hypotension is not a hazard, serving instead to decrease regurgitant flow and reduce the volume overload of the left ventricle. If left ventricular function is depressed, elective noncardiac surgery raises the question of preemptive replacement of the aortic valve. A tissue valve is preferred to avoid anticoagulants if subsequent noncardiac surgery is anticipated. Emergency noncardiac operation in the presence of depressed left ventricular function calls for hemodynamic monitoring and reduction of postoperative pharmacological afterload.

EBSTEIN’S ANOMALY OF THE TRICUSPID VALVE

EBSTEIN’S ANOMALY OF THE TRICUSPID VALVE (see [For More Information] ). Patients with the acyanotic form of the anomaly confront noncardiac surgery with four risks: (1) the functionally inadequate right ventricle, (2) atrial tachyarrhythmias with or without accessory pathways, (3) paradoxical embolism through an intraatrial communication, and (4) infective endocarditis on the malformed tricuspid valve. Right ventricular failure is less a perioperative risk than sudden atrial flutter or fibrillation, especially with rapid antegrade conduction through bypass tracts. Patients with histories of rapid heart action or fusion beats (type B Wolff-Parkinson-White) on scalar ECG require electrocardiographic monitoring. Postoperative thrombophlebitis and the attendant risk of paradoxical embolization are reduced by the use of support hose and early ambulation.

OSTIUM SECUNDUM ATRIAL SEPTAL DEFECT

OSTIUM SECUNDUM ATRIAL SEPTAL DEFECT (see [For More Information] ). Young adults with uncomplicated defects experience comparatively little risk during noncardiac surgery, with two exceptions. In response to hemorrhage, systemic resistance rises and venous return diminishes, a combination that augments the left-to-right interatrial shunt, sometimes considerably. An additional concern is the risk of paradoxical emboli from leg veins because thrombi carried by the inferior vena cava tend to stream across the atrial septal defect into the systemic circulation. Meticulous leg care and early ambulation minimize venous stasis.

CYANOTIC CONGENITAL HEART DISEASE

CYANOTIC CONGENITAL HEART DISEASE. Cyanotic adults have an increased incidence of acute cholecystitis caused by calcium bilirubinate gallstones (Fig. 30–12 Fig. 30–12 ). Perioperative improvement in hemostasis in cyanotic patients can be addressed if surgery is elective, with guidelines set forth earlier. Inhalation of oxygen may raise arterial oxygen saturation even in the presence of a right-to-left shunt, but there is little evidence that its routine perioperative use is beneficial. Intravenous lines, infusions, and drugs must be managed with special care in cyanotic patients. Introduction of air or particles into peripheral veins risks delivery into the systemic circulation because of the right-to-left shunt. Use of an air/particle filter obviates the risk.

Older patients with Fallot’s tetralogy may come to noncardiac surgery without intracardiac repair or with only a shunt inserted in infancy or childhood. Meticulous perioperative monitoring of oxygen saturation (pulse oximeter) and blood pressure is important, because a sudden fall in systemic resistance may precipitate intense cyanosis and occasionally death, or a sudden rise in systemic resistance may abruptly and dangerously depress systemic blood flow.155 The risk of postoperative postural hypotension is mentioned below. Susceptibility to infective endocarditis requires prophylaxis.

Cyanotic patients with elevated pulmonary vascular resistance face noncardiac surgery with risks inherent in the cyanosis itself in addition to the formidable risks of pulmonary vascular disease. Fixed pulmonary resistance precludes rapid adaptive responses to labile intraoperative or postoperative hemodynamic changes. In Eisenmenger’s complex or physiologically analogous lesions, a sudden fall or a sudden rise in systemic vascular resistance precipitates responses similar to those already described in Fallot’s tetralogy. Every effort should be made to minimize the postural hypotension that tends to occur during early convalescence in patients having general anesthesia.155 Because the attendant drop in systemic vascular resistance suddenly augments the right-to-left shunt, convalescent cyanotic patients with pulmonary vascular disease should change positions slowly until the risk of postoperative postural hypotension has abated.

Noncardiac Surgery in Adults with Repaired Congenital Heart Disease

Noncardiac Surgery in Adults with Repaired Congenital Heart Disease

Adults who have undergone reparative surgery for congenital heart disease comprise an increasing percentage of patients who require subsequent noncardiac operations. If cardiac surgery is curative (division of a small patent ductus arteriosus), there is no added risk of a noncardiac surgical procedure. Early correction of simple pulmonary valve stenosis is also close to a cure. Subsequent noncardiac surgery imposes little or no risk, including, in all probability, susceptibility to infective endocarditis. Closure of an ostium secundum atrial septal defect in childhood is close to a cure.

Valvular residua and sequelae after cardiac surgery or therapeutic catheterization are relevant in the medical management of patients who undergo noncardiac surgery in adulthood.189 Successful repair of coarctation of the aorta may leave behind a functionally normal bicuspid aortic valve that is susceptible to infective endocarditis. After complete relief of congenital pulmonary valve stenosis by direct repair or balloon dilatation, the risk of infective endocarditis is low if not absent, but the functional adequacy of the right ventricle is an important perioperative variable. In Fallot’s tetralogy, reconstruction of the right ventricular outflow tract may largely or entirely abolish the gradient. If the function of the right ventricle is satisfactory, and if postoperative pulmonary regurgitation is no more than moderate, the risk of noncardiac surgery is small. Infective endocarditis prophylaxis is advisable even though susceptibility is relatively low.

After surgical repair of Ebstein’s anomaly of the tricuspid valve (tricuspid reconstruction and division of bypass tracts), atrial arrhythmias remain a concern during noncardiac surgery, but without fear of accelerated conduction (Fig. 30–7 Fig. 30–7 ). Closure of the intraatrial communication eliminates cyanosis, so the hematological derangements are no longer issues, and the potential for paradoxical embolization is eliminated. The postoperative right ventricle is not functionally normal, but the hemodynamic risk during subsequent noncardiac surgery is small. If residual tricuspid regurgitation is more than mild, prophylaxis for infective endocarditis is advisable.

PROSTHETIC MECHANICAL VALVES

PROSTHETIC MECHANICAL VALVES. These devices (see [For More Information] ) complicate the management of noncardiac surgery. The immediate issue is anticoagulation in addition to and apart from the risk of infective endocarditis. If noncardiac surgery is elective, and if the prosthesis carries a high thromboembolic risk (mitral location with atrial fibrillation), warfarin should be replaced with an in-hospital continuous infusion of heparin that is discontinued 4 to 6 hours before the elective surgery, restarted within 48 hours after surgery, and then replaced by warfarin. For a lower-risk prosthetic valve in the aortic location, it is relatively safe to discontinue warfarin 2 to 3 days before noncardiac surgery and resume the drug 2 to 3 days after surgery.

Emergency noncardiac surgery in an anticoagulated patient with a mechanical prosthesis is managed differently. Prompt restitution of hemostasis requires infusion of fresh frozen plasma. Cessation of warfarin and administration of vitamin K do not achieve immediate reversal of the anticoagulant effects, which persist for 24 hours or more. If vitamin K is used, the preoperative response to readministration of warfarin is blunted.

ELECTROPHYSIOLOGICAL SEQUELAE

ELECTROPHYSIOLOGICAL SEQUELAE. Electrophysiological sequelae after reparative surgery are important concerns during management of subsequent noncardiac surgery. The most diverse and complex sequelae are incurred by intraatrial repairs (Mustard or Senning operations) for complete transposition of the great arteries, and require monitoring during noncardiac surgery. Intraventricular surgery may result in electrophysiological sequelae that are potentially important. Awareness of the presence or potential presence of these sequelae decreases perioperative risk.

After repair of coarctation of the aorta, systemic hypertension may persist or recur even if the obstruction has been completely relieved, but the incidence is declining owing to the success of early operation. Nevertheless, pharmacological control of perioperative hypertension is sometimes necessary during noncardiac surgery. The greater the duration of systemic hypertension before repair, the greater the likelihood of premature coronary artery disease—a point to be considered in subsequent perioperative management.

VENTRICULAR FUNCTION

VENTRICULAR FUNCTION. The adequacy of ventricular function (left, right, or single ventricle) is a major determinant of risk during noncardiac surgery in adults. Excessive intravenous fluids should be avoided, and hemodynamic monitoring used when the morphological substrate permits insertion of a flotation catheter.155

Medical management during noncardiac surgery must also take into account acquired diseases of the heart and circulation, especially coronary artery disease and systemic hypertension, as well as noncardiac acquired medical disorders such as renal, respiratory, gastrointestinal, or endocrinological.

Postoperative Residua and Sequelae

Residua are defined as cardiac, vascular, or noncardiovascular disorders that are unavoidably left behind at the time of reparative heart surgery189 (Table 30–3 Table 30–3 ). With few exceptions, residua do not result from surgery having fallen short of its goal, at least in a technical sense.190 By contrast, sequelae are defined as alterations or disorders that are intentionally incurred—occasionally or invariably—at the time of reparative surgery and are looked upon as necessary and acceptable consequences of surgery189 (Table 30–4 Table 30–4 ). Complications are unintentional aftermaths of reparative surgery that range in degree from inconsequential to fatal. Complications and sequelae imperceptibly merge. Surgery is curative if there are no cardiac or vascular residua, sequelae, or complications after surgery. “Curative” means that normal cardiovascular structure and function are achieved and maintained, life expectancy is normal, and further medical or surgical treatment for the congenital heart disease is unnecessary. This ideal seldom is realized, and even curative cardiac surgery does not preclude noncardiac residua.189

Residua

Residua

ELECTROPHYSIOLOGICAL RESIDUA

ELECTROPHYSIOLOGICAL RESIDUA. With some exceptions, these residua are inherent components of certain congenital cardiac malformations.189 The abnormalities are often evident in standard preoperative 12-lead ECG’s, and persist—sometimes harmlessly, sometimes not so harmlessly—after reparative surgery. Electrophysiological residua include (1) axis deviation, especially left; (2) conduction defects, especially atrioventricular; (3) disorders of impulse formation, especially of the sinus node; and (4) arrhythmias, especially atrial.

RESIDUAL ABNORMALITIES OF CARDIAC VALVES

RESIDUAL ABNORMALITIES OF CARDIAC VALVES. These residua fall into three general categories: (1) congenitally malformed cardiac valves that are functionally normal and do not require attention during reparative surgery; (2) intrinsically normal cardiac valves that are rendered incompetent because of the physiological stress imposed by the congenital malformation that prompted surgical repair; and (3) residually incompetent or stenotic congenitally malformed cardiac valves that do not lend themselves to complete repair. Aortic valve abnormalities that represent unimportant residua include functionally normal bicuspid aortic valve with coarctation of the aorta and mild aortic regurgitation that may accompany Fallot’s tetralogy. Residual congenital mitral valve abnormalities that are functionally unimportant include the “cleft” but competent anterior mitral leaflet of an atrioventricular septal defect and the reduction in interpapillary muscle distance associated with coarctation of the aorta. Postoperative residual incompetence of an intrinsically normal pulmonary or tricuspid valve is usually the result of pulmonary hypertension or obstruction to right ventricular outflow.

RESIDUAL VENTRICULAR ABNORMALITIES

RESIDUAL VENTRICULAR ABNORMALITIES. Certain ventricular abnormalities are obligatory and permanent after reparative surgery, such as the morphology of a chamber, or may change with the passage of time, such as alterations in chamber mass and function. In patients undergoing either an atrial switch operation for complete transposition of the great arteries, or operation for congenitally corrected transposition of the great arteries, a postoperative residuum of fundamental importance is the presence of a morphological right ventricle in the systemic location. A pivotal question is whether that right ventricle, perfused by a right coronary artery, can, in the long term, perform as a systemic chamber as well as a morphological left ventricle perfused by a left coronary artery.

Date: 2014-12-21; view: 1049