Congenitally Corrected Transposition 

Updated: Jan 22, 2019
Author: Arnold S Baas, MD, FACC, FACP; Chief Editor: Yasmine S Ali, MD, FACC, FACP, MSCI 

Overview

Practice Essentials

Congenitally corrected transposition of the great arteries (CCTGA) is a rare congenital heart defect in which the heart twists abnormally during fetal development and the ventricles are reversed. Patients and/or their parents/guardians should receive pregnancy counseling,[1]  education regarding infective endocarditis prophylaxis, as well as counseling about moderate and not heavy exercise routines.[2]

See the image below.

Subcostal view of a 1-year-old child with L-transp Subcostal view of a 1-year-old child with L-transposition of the great arteries, valvular and subvalvular pulmonic stenosis, and a moderate outlet ventriculoseptal defect (VSD). Note the ventriculoarterial discordance. Note the posterior, rightward position of the pulmonary artery. [PA = pulmonary artery, LV = left ventricle, RV = right ventricle].

Signs and symptoms

Symptoms usually reflect associated cardiac anomalies. The most common presenting features include the following:

  • bradycardia related to high-degree AV heart block

  • a single loud second heart sound, which is often palpable to the left of the sternum, arising from the anteriorly positioned aortic valve

  • heart murmur due to associated ventricular septal defect, pulmonic stenosis, or tricuspid regurgitation

  • cyanosis (only if there is an associated cardiac defect, such as pulmonary atresia or ventricular septal defect)

  • heart failure

  • tachyarrhythmia

See Clinical Presentation for more detail.

Diagnosis

This condition is usually diagnosed later in childhood or in early adult life when patients present with complete heart block or heart failure due to right ventricular decompensation or systemic tricuspid valve regurgitation.

Diagnosis may require some or all of the following tests:

  • Echocardiogram

  • Chest radiography

  • Transesophageal echocardiography

  • Cardiac MRI

  • Electrocardiography

Echocardiogram and cardiac MRI are most commonly used in the diagnosis of CCTGA.

See Workup for more detail.

Management

Medical care

There is little evidence that established medical treatment options for left ventricle dysfunction (ACE inhibitors, beta-blockers, nitrates) produce similar outcomes for systemic right ventricles. Caution should be used with administration of beta-blockers, as complete heart block may be precipitated in these patients with known conduction system abnormalities. Ultimately, patients with failing systemic ventricular function may best be served by cardiac transplantation.

Surgical care

For patients who need surgery, the type of operation will vary according to the associated defects. There are several options available including the following:

  • Ventricular septal defect closure (VSD) and insertion of a tube (conduit) between the heart and the lungs

  • Tricuspid valve replacement

  • Switch procedures, including double switch and the Senning-Rastelli procedure

Early pacemaker placement is recommended in the setting of complete heart block either during or after surgical intervention, or if any significant associated defect, such as cardiomegaly, decreased right ventricular function, symptomatic bradycardia, or heart failure, is present.

See Treatment and Medication for more detail.

Pathophysiology

Congenitally corrected transposition of the great vessels is a rare congenital heart defect associated with multiple cardiac morphologic abnormalities and conduction defects.

During embryologic development, left-handed looping of the heart tube results in atrioventricular (AV) discordance, and the aortopulmonary septum fails to rotate 180°, resulting in ventriculoarterial discordance. Blood flows in an effective sequence, hence the name corrected; however, the right ventricle supports the systemic circulation in this disorder.

Venous blood returns from the body into the right atrium before passing through the mitral valve into a morphological left ventricle. Blood then enters the lungs via the pulmonic valve into the main pulmonary artery. Pulmonary venous blood returns to the left atrium and then passes through the tricuspid valve to the morphological right ventricle, exiting to the aorta via the aortic valve. The aorta is positioned anterior and to the left of the pulmonary artery. In effect, the ventricles are transposed.

Etiology

Causes and exposures associated with congenitally corrected transposition of the great arteries have not been identified clearly.

A substantial number of patients with congenital heart disease have a deletion of chromosome band 22q11. These deletions have been associated with abnormalities of the pulmonary arteries and aortic arch or its major branches regardless of the intracardiac anatomy.[3]  Rarely, these deletions are found in patients with transposition of the great vessels. In one series, none of 45 patients with transposition had the deletion.

Epidemiology

United States data

Data from the Baltimore-Washington Infant Study supported the fact that congenitally corrected transposition is a rare disorder.[4]  As many as 40 infants per 100,000 live births are affected by congenitally corrected transposition of the great vessels; this is fewer than 1% of all congenital heart defects.

International data

This disorder is reported in 0.5% of patients with congenital heart disease, and the literature reports fewer than 1000 cases. Most pediatric cardiologists have seen multiple cases of congenitally corrected transposition of the great vessels; however, the true prevalence of the malformation is not known.

Prognosis

Patient prognosis depends on AV conduction, arrhythmias, structural abnormalities, and degree of hemodynamic disturbance.[5]

Sudden death may be related to the onset of complete heart block or atrial or ventricular arrhythmias.

Right ventricular failure can develop over time. This may be related to coronary perfusion mismatch as the right ventricle is supplied by a single coronary artery. In addition, differences in right and left ventricular fiber orientation, geometry, and microscopic structural features may play a role in early failure of the right ventricle when functioning as the systemic ventricle. Poor prognostic indicators include cyanosis, polycythemia, pulmonary vascular obstructive disease, tricuspid regurgitation, younger age at surgery, larger preoperative shunt size, and lower right ventricular ejection fraction. A multicenter series of 182 patients with congenitally corrected transposition of the great arteries demonstrated that 25% of patients without associated cardiac lesions and 67% of patients with other cardiac abnormalities developed congestive heart failure by age 45.[6]

Morbidity/mortality

Note the following:

  • Ten-year survival rate ranges from 64-83% from the time of diagnosis and is dependent on associated anomalies.

  • Freedom[7]  reported an operative mortality rate of 6% and a 15-year actuarial survival rate of 48% in a cohort of patients with congenitally corrected transposition of the great vessels at the Hospital for Sick Children in Toronto.

  • A rare patient without associated cardiac anomalies may have a much more benign course, and literature documents many examples of these patients being diagnosed in the sixth and seventh decades of life.[8, 9, 10]

  • A median age at death of 40 years has been reported in both patients who have undergone operation and those who have not.

Complications

Major postoperative residual complications include contractile dysfunction of the systemic right ventricle, progressive tricuspid (systemic AV) regurgitation, complete heart block, atrial or ventricular arrhythmias, and infective endocarditis. Patients may develop conduit or homograph dysfunction postoperatively.

Systemic AV valve regurgitation is well described after surgery even when the valve has not been directly manipulated.

 

Presentation

History

Symptoms usually reflect associated cardiac anomalies. The uncommon patient with isolated congenitally corrected transposition of the great vessels should be asymptomatic early in life. The diagnosis may be established via a chest radiograph or electrocardiogram performed for another reason; otherwise, this condition is usually diagnosed later in childhood or in early adult life when patients present with complete heart block or heart failure due to right ventricular decompensation or systemic tricuspid valve regurgitation. The most common presenting features are (1) bradycardia related to high-degree AV heart block; (2) a single loud second heart sound, which is often palpable to the left of the sternum, arising from the anteriorly positioned aortic valve; (3) heart murmur due to associated ventricular septal defect, pulmonic stenosis, or tricuspid regurgitation; (4) cyanosis; (5) heart failure; or (6) tachyarrhythmia.

Associated cardiac structural findings include those discussed below

Atrial situs

The atria are situs solitus in 85-90% of patients.

Ventricular septal defect

This is the most common associated cardiac malformation, with an incidence of 60-70% in clinical series and nearly 80% in reviews of autopsied cases. The defect is usually large and perimembranous in location but can occur in any position along the ventricular septum.

The perimembranous ventricular septal defect tends to be subpulmonary.

Subarterial ventricular septal defects, roofed by the semilunar valves, have been described in Asian patients but are uncommon in the Western world.

The resulting left-to-right shunt is usually large.

Conduction system abnormalities

The sinus node is positioned normally but the anatomical situation precludes normal conduction because the AV conduction tissue is profoundly abnormal. The normal AV node cannot give rise to the penetrating AV bundle. An anomalous second AV node is the functional AV conduction system in many patients, generally located beneath the opening of the right atrial appendage at the lateral margin between the pulmonic valve and the mitral valve; thus, the node has an anterior position and gives rise to the AV bundle immediately underneath the right anterior pulmonic valve leaflet. This accessory node is not always present and may be hypoplastic or nonfunctional.

Complete heart block occurs in 30% of patients and may be present at birth or develop at a rate of 2% per year. Other conduction disturbances described include sick sinus syndrome, atrial flutter, re-entrant AV tachycardia due to an accessory pathway along the tricuspid valve annulus, and ventricular tachycardia.

Coronary anatomy

The coronary arteries have a mirror image location. Dabizzi et al found coronary artery-ventricular concordance in 11 of 13 patients who underwent angiography.[11] Early entrapment of coronaries in fat or myocardium is also common in this cohort of patients.

Left ventricular outflow tract obstruction

Left ventricular outflow tract obstruction (pulmonary outflow tract) occurs in 30-50% of patients and is typically associated with a ventricular septal defect. Freedom[7] reported that, of patients with pulmonary outflow tract obstruction and a ventricular septal defect, approximately one third have tricuspid valve deformities.

Multiple obstructive lesions have been described, including wedging of the outflow tract by inverted mitral and tricuspid valves, fixed infundibular and valvar pulmonic stenosis, tissue bags derived from intact or perforated membranous septum, blood cysts attached to the pulmonary valve, or a subpulmonic tag originating from both sides of the ventricular septum.

Abnormal tricuspid valve morphology

The incidence is 90% in autopsy series, but clinically relevant abnormalities are less common and include dysplasia (malformed or imperforate leaflets), apical displacement of the septal leaflet (Ebstein-like malformation), or straddling and overriding of an inlet ventricular septal defect.

Other

Other associated cardiac structural findings include the following:

  • Straddling or overriding left AV valve (also abnormalities of cusp number or tension apparatus)

  • Coarctation of the aorta

  • Interruption of the aortic arch

  • Aortic or subaortic stenosis

  • Hypoplasia of one ventricle: Usually, the disturbed AV valve is ipsilateral to the hypoplastic chamber.

  • Common arterial trunk (functional or anatomic aortic atresia)

  • Abnormal conduction tissue

Physical Examination

The physical findings depend on the associated anomalies, such as the following examples:

  • In patients with large left-to-right shunts, the precordium is hyperdynamic, with evidence of cardiac enlargement.

  • Individuals with pulmonic stenosis tend to have a relatively quiet precordium, and cyanosis is prominent.

  • A loud and often palpable single second heart sound is commonly present at the left sternal border and is related to the anterior and leftward position of the aorta.

  • The murmur of left AV valve (tricuspid) regurgitation may be mistaken for the typical pansystolic murmur of ventricular septal defect since it is often maximal at the fourth intercostal space near the sternum rather than at the apex, reflecting the side by side orientation of the ventricles in congenitally corrected transposition with the ventricular septum in the sagittal plane.

  • Although the murmur of pulmonary stenosis is often heard well at the pulmonary area, it may be loudest lower on the left side or at the aortic area, because of the inferior and posteriorly displaced pulmonary valve.

 

DDx

 

Workup

Laboratory Studies

Cyanotic conditions may be associated with elevations in red cell volume reflected in the hemoglobin and hematocrit. This elevation is a reactive process to the body's demand for oxygen and is not a primary polycythemia. CBC count, clotting profile, renal function, and ferritin and uric acid levels should be measured.

Imaging Studies

Echocardiography either in utero or by transthoracic or transesophageal imaging generally confirms the diagnosis (see following images).

Subcostal view of a 1-year-old child with L-transp Subcostal view of a 1-year-old child with L-transposition of the great arteries, valvular and subvalvular pulmonic stenosis, and a moderate outlet ventriculoseptal defect (VSD). Note the ventriculoarterial discordance. Note the posterior, rightward position of the pulmonary artery. [PA = pulmonary artery, LV = left ventricle, RV = right ventricle].
Apical image revealing atrioventricular discordanc Apical image revealing atrioventricular discordance. Note the pulmonary venous return into the left atrium, with sequential flow through the tricuspid valve to the right ventricle. The right ventricle is systemic. [LA = left atrium, RA = right atrium, LV = left ventricle, RV = right ventricle].

Chest radiography reveals parallel great vessels. The upper left heart border is formed by the aorta and appears straight, and the pulmonary artery knob is absent because of the rightward, posterior displacement of the artery.

Transesophageal echocardiography (TEE) may be needed to assess ventricular function, AV valve regurgitation, and pulmonary outflow tract if this information is not provided by transthoracic imaging, particularly in the patient who has undergone an operation.

Nuclear cardiology assessment of ventricular function may be indicated. Radionuclide angiography usually better reports right ventricular function compared with echocardiography.

Cardiac magnetic resonance imaging (MRI) evaluates ventricular volumes, ventricular function, and valvular or conduit function. It is reasonable (class IIa recommendation) in adults with CCTGA to determine systemic RV dimensions and systolic function.[12]

Other Tests

Electrocardiography is affected by the associated cardiac anomalies but commonly shows AV block, atrial arrhythmias, and abnormal initial ventricular activation due to disordered anatomy of the conduction system. With ventricular inversion, the ventricular bundle branches are inverted and the initial activation is oriented from right-to-left. This results in reversal of the normal Q-wave pattern in the precordial leads such that Q waves are present in the right precordial leads but absent in the left precordial leads. The ECG in patients with congenitally corrected transposition may therefore be misinterpreted as inferior myocardial infarction.

A Holter monitor is used for assessment of AV block and atrial arrhythmias.

Procedures

Cardiac catheterization carries a significant risk of inducing transient or complete heart block. Note the following:

  • Use caution. Transient or permanent complete heart block may be induced in this condition because the conduction system lies just below the pulmonic valve.

  • Always use a balloon-tipped catheter to approach the pulmonic valve. Always have transvenous pacing capability available during this procedure.

  • Limit catheterization to assessment of pulmonic stenosis, shunt volume, pulmonary vascular resistance before and in response to therapy, and angiography in preparation for reparative surgery.

Histologic Findings

Anderson et al identified both a normal-appearing AV node in the usual position without connections to a penetrating bundle and an accessory AV node located in the right atrium at the junction of the mitral valve and the left border of the right atrial appendage.[13, 14] This second AV node connects directly to an aberrantly located penetrating bundle. The bundle passes laterally onto the pulmonary outflow tract just below the pulmonic valve, then descends to the interventricular septum, remaining on the right side of the septum rather than the left side (ie, normal system). The course varies depending on the integrity of the ventricular septum.

 

Treatment

Medical Care

Connelly et al reported infective endocarditis in as many as 11% of a 52-patient series.[15] In most cases, antibiotic prophylaxis is indicated according to the recommendations of the American Heart Association.

Management of heart failure may entail use of diuretic drugs, digitalis, beta-blockers, and/or angiotensin-converting enzyme (ACE) inhibitor therapy. All are helpful for symptomatic therapy in particular individuals, but none are demonstrated to improve mortality rates in patients with congenital heart disease. In fact, a systematic review of medical therapy for systemic right ventricles for the 2018 AHA/ACC Guideline for the Management of Adults with Congenital Heart disease did not show any evidence of benefit of medical therapy (beta blockers, ACE inhibitors, ARBs, and aldosterone antagonists) in patients with systemic right ventricles.[16]

It is tempting to suggest that established treatment outcomes for severe LV dysfunction (ACE inhibitor, beta-blocker, nitrate, hydralazine, aldosterone antagonist) would have similar effects in patients with RV failure in the setting of congenitally corrected transposition of the great arteries; however, little evidence-based data is available to support improvements in cardiac outcomes or total mortality as was observed when treating LV systolic dysfunction. Furthermore, caution should be used with administration of beta-blockers, as complete heart block may be precipitated in these patients with known conduction system abnormalities. Ultimately, patients with failing systemic ventricular function, if good candidates, may best be served by cardiac transplantation.

Surgical Care

Surgery is recommended only for symptomatic associated lesions and when significant hemodynamic benefit is expected.

Common postoperative complications include complete heart block and progressive tricuspid regurgitation, even when these anatomic structures are not manipulated directly.

The altered location of a fragile conduction system and the mirror image coronary anatomy may complicate surgical repair. The right-sided coronary artery often divides into the anterior descending and circumflex branches, which supply the morphological left ventricle. This complicates placement of a conduit in patients to relieve pulmonic stenosis.

In a study of 62 adults with congenitally corrected transposition of the great arteries (ccTGA), Helsen and colleagues found that native or surgically induced pulmonary outflow tract obstruction (POTO) was associated with an improved event-free survival. Event-free survival was defined as the composite of all-cause mortality, heart transplantation, or congestive heart failure. In the presence of POTO, the mean progression-free interval for the composite endpoint increased from 11.2 years to 18.1 years (P=0.035).[17]

Ventricular septal defect closure is generally performed when symptoms of CHF or failure to thrive do not respond to medical therapy or when pulmonary vascular pressures are increasing. Operative mortality rate among 15 patients with ventricular septal defect reported by Termignon et al[18] was 13%, with 33% requiring permanent pacemaker implantation for complete heart block. Two patients had late deaths and 6 required reoperation for tricuspid valve replacement. Of note, ventricular septal defect closure may exacerbate systemic AV valve (morphologic tricuspid valve) regurgitation due to septal shift and distortion of the AV valve annulus.

Tricuspid valve replacement can be performed for severe tricuspid incompetence. Repair of the dysplastic or displaced valve is not usually feasible. Tricuspid valve replacement should also be considered when severity is more than grade 2/4 and other intracardiac lesions are being corrected. Replacement of the tricuspid valve is recommended for symptomatic (class I) or asymptomatic (class IIa) adults with CCTGA and severe tricudpid regurgitation, if they have preserved or only mildly reduced systemic ventricular function.[12]

Switch procedures attempt to correct the underlying malformation anatomically, trying to minimize the risk of heart block or tricuspid incompetence. Note the following:

  • The atrial and ventricular double switch procedure is performed when pulmonic stenosis and a large ventricular septal defect are present.[19] Feasibility of the repair depends on the location of the ventricular septal defect. The repair requires proximity of a ventricular septal defect to the aorta. Chordal malattachments or deformation of the mitral valve inhibiting support of systemic pressures may exclude this option.

  • The Rastelli procedure, originally described by Gian Carlo Rastelli in 1969, for patients with D-transposition of the great arteries, large ventricular septal defect, and naturally occurring pulmonary outflow obstruction involves routing the left ventricle to the aorta via a prosthetic baffle through the ventricular septal defect into the right ventricle to the aortic valve and placing a conduit from the right ventricle to the pulmonary artery bifurcation. In patients with moderate pulmonary stenosis, self-palliation has occurred and infants can survive for many years without intervention.[20]

    Post-Rastelli repair with left ventricle to aortic Post-Rastelli repair with left ventricle to aortic baffle through a ventriculoseptal defect (VSD) complicated by subaortic stenosis.
  • The atrial switch for L-transposition takes the form of the Senning or Mustard procedure with additional repair of any ventricular septal defect. These procedures involve intra-atrial baffles to route venous blood toward the right ventricle and pulmonary artery, and oxygenated blood from the pulmonary veins into the left ventricle and out to the body. The Senning procedure is technically advanced to better preserve intrinsic AV nodal function. The atrial switch is coupled either with an arterial switch (part of the Double Switch) or a Rastelli procedure. The right ventricle and tricuspid valve will become subpulmonic at this point.

  • The arterial switch operation is the most current procedure available, generally performed within 2 weeks of birth. In this procedure, the left ventricle must have tolerated near-systemic pressures prior to the switch. Pulmonary artery banding prior to a definitive repair can prepare the ventricle if a sufficient ventricular septal defect is not present; however, based on results from repair of complete transposition of the great arteries, long-term outcome after atrial switch is a concern. Late complications include atrial arrhythmias and vena cava or pulmonary venous obstruction.

In a study of 52 patients reported by Termignon et al,[18] the operative mortality rate of a classic repair of congenitally corrected transposition of the great arteries and ventricular septal defect was 16% and the rate of complete heart block was 24% after the repair. Six additional late deaths and 5 patients who required reoperation for tricuspid valve replacement were also listed. Survival rates were 83% at 1 year and 55% at 5 years after the repair.

Early pacemaker placement is recommended in the setting of complete heart block either during or after surgical intervention or if any significant associated defect, such as cardiomegaly, decreased right ventricular function, symptomatic bradycardia, or heart failure, is present. Unfortunately, transvenous pacemaker implantation may also precipitate worsening AV valve regurgitation and deterioration of systemic ventricular performance by altering position of the ventricular septum during pacing, resulting in incomplete systolic coaptation of the tricuspid valve and, hence, worsening regurgitation.[21]

In a retrospective review of 53 patients, Hofferberth et al found that late-onset systemic ventricular dysfunction is a major complication associated with univentricular pacing in patients with congenitally corrected transposition of the great arteries (ccTGA). Patients with ccTGA who develop heart block should undergo primary biventricular pacing, which prevents late systemic ventricular dysfunction. Preemptive placement of biventricular pacing leads at the time of anatomical repair or another permanent palliative procedure will facilitate later biventricular pacing if heart block develops.[22]

Percutaneous pulmonary valvuloplasty is not recommended in patients with transposition of the great vessels because of expected complete heart block.

Consultations

Patients with congenitally corrected transposition should be managed and seen regularly by cardiologists with expertise and training in congenital heart disease. Furthermore, patients referred for cardiac catheterization, electrophysiologic procedures, or percutaneous and/or surgical procedures should be referred to centers with expertise in congenital heart disease.

Activity

The reduced ability of the right ventricle to support systemic pressure and associated anomalies limit activity. The 1994 Bethesda Conference included patients with congenitally corrected transposition of the great vessels, and specific recommendations to limit activity were not made. Individual assessment should include serial evaluations of right ventricular function.

Prevention

Serial echocardiograms to monitor right ventricular (ie, systemic ventricular) size and function, and tricuspid (systemic AV) valve regurgitation can help to time operative repair and assess effects of medical intervention. Data are emerging using right ventricular radionuclide angiography and magnetic resonance angiography for both perfusion and function assessments. Multiple gated acquisition (MUGA) scans can also accurately describe right ventricular function and dimension.

  • Guidelines for the Clinical Application of Echocardiography by an ACC/AHA Task Force suggest that class I indications for follow-up echocardiograms in patients with known congenital heart disease include any change in clinical findings, any uncertainty of the original diagnosis or of the structural abnormalities or hemodynamics, or periodic monitoring for those whose ventricular function and AV valve regurgitation must be followed.[23]

  • The timing of periodic monitoring is not specified. Most centers monitor patients with serial echocardiography; more frequent examinations are warranted for any change in clinical status.

  • Dobutamine stress echocardiography may also be helpful. In asymptomatic children after arterial switch surgery, baseline left ventricular function is often mildly impaired with reversible areas of ischemia revealed, despite normal coronary perfusion.

Long-Term Monitoring

Depending on the functional status and level of right ventricular dysfunction, adult patients with CCTGA should follow up with an outpatient ACHD cardiologist every 3-12 months. ECG and echocardiograms should be obtained yearly. Holter monitors, Cardiac MRIs, and exercise testing can also be obtained at regular intervals ranging from 12-60 months depending on each individual’s functional status and symptoms.[12]

 

Medication

Medication Summary

Medications include antibiotic prophylaxis for procedures or dental work and standard therapy for heart failure (diuretic drugs, digitalis, beta-blockers, and angiotensin converting enzyme [ACE] inhibitors). All are helpful for symptomatic therapy, but none are demonstrated to improve mortality rates.

Antibiotics

Class Summary

Empiric antimicrobial therapy should cover all likely pathogens in the context of this clinical setting.

Amoxicillin (Amoxil, Trimox)

Interferes with synthesis of cell wall mucopeptides during active multiplication, resulting in bactericidal activity against susceptible bacteria. Recommended prophylactic regimen for dental, oral, or upper respiratory procedures per American Heart Association guidelines.

Ampicillin (Omnipen, Principen)

For prophylaxis in patients undergoing dental, oral, or respiratory tract procedures. Patients unable to take oral medications may be given ampicillin IV.

Clindamycin (Cleocin)

Used in penicillin-allergic patients undergoing dental, oral, or respiratory tract procedures.

Diuretics

Class Summary

These agents are used for treatment of pulmonary or hepatic congestion and peripheral edema due to heart failure.

Furosemide (Lasix)

Increases excretion of water by interfering with chloride-binding cotransport system in kidney, which, in turn, inhibits sodium and chloride reabsorption in ascending loop of Henle and distal renal tubule. Titrate dose according to response.

Available as 20-, 40-, and 80-mg tablets.

Angiotensin converting enzyme inhibitors

Class Summary

These agents offer a mortality benefit in CHF and left ventricular dysfunction in patients with structurally normal hearts.

Lisinopril (Prinivil, Zestril)

Prevents conversion of angiotensin I to angiotensin II, a potent vasoconstrictor, resulting in lower aldosterone secretion. Not recommended in patients with one kidney.

Ramipril (Altace)

Prevents conversion of angiotensin I to angiotensin II, a potent vasoconstrictor, resulting in lower aldosterone secretion.

Captopril (Capoten)

Prevents conversion of angiotensin I to angiotensin II, a potent vasoconstrictor, resulting in lower aldosterone secretion.

Enalapril (Vasotec)

Competitive inhibitor of ACE. Reduces angiotensin II levels, decreases aldosterone secretion.

Quinapril (Accupril)

Prevents conversion of angiotensin I to angiotensin II, a potent vasoconstrictor, resulting in lower aldosterone secretion.

Cardiac glycosides

Class Summary

These agents inhibit sodium-potassium adenosine triphosphatase (ATPase), increasing intracellular calcium. Used in treatment of mild to moderately severe CHF.

Digoxin (Lanoxin)

Cardiac glycoside with direct inotropic effects in addition to indirect effects on cardiovascular system. Acts directly on cardiac muscle, increasing myocardial systolic contractions through intracellular calcium release. Its indirect actions result in increased carotid sinus nerve activity and enhanced sympathetic withdrawal for any given increase in mean arterial pressure.

Beta-blockers

Class Summary

These agents have not been studied in patients with right systemic ventricle heart failure. Beta-blockers have mortality benefits in the general heart failure population and must be considered in the population of patients with complex congenital heart disease. Initiate beta-blockers only in patients whose condition is stable, without CHF symptoms, and titrate slowly.

Metoprolol (Lopressor, Toprol XL)

Selective beta1-adrenergic receptor blocker that decreases automaticity of contractions. During IV administration, carefully monitor BP, heart rate, and ECG.

Carvedilol (Coreg)

Used to reduce disease progression in CHF. Effects include beta-blockade, alpha1-blockade, and antioxidant properties.