I. Anomalous Origin of the Left Coronary Artery (Bland-White-Garland Syndrome, Alcapa Syndrome)
A. Pathology and Pathophysiology
The left coronary artery (LCA) arises abnormally from the main PA. Postnatal decrease in the PA pressure results in ineffective perfusion of the LCA, producing ischemia and infarction of the LV that is normally perfused by the LCA.
B. Clinical Manifestations
- 1.
The newborn patient is usually asymptomatic until the PA pressure falls to a critical level. Symptoms appear at 2 to 3 months of age and consist of recurring episodes of distress (anginal pain) with signs of CHF. Heart murmur usually is absent.
- 2.
Chest radiographs show cardiomegaly. The ECG shows anterolateral myocardial infarction pattern consisting of abnormally deep and wide Q waves, inverted T waves, and ST-segment shift in leads I, aVL, and most precordial leads (V2 through V6).
- 3.
Two-dimensional echo with color flow mapping is diagnostic and has replaced cardiac catheterization. The absence of normal LCA arising from the aorta raises the possibility of the condition. Instead, the LCA is seen to connect to the main PA. Color Doppler examination may show retrograde flow into the main PA from the LCA. The right coronary artery may be enlarged. The left ventricle may enlarge with reduced LV systolic function. Increased echogenicity of papillary muscles and adjacent endocardium suggests fibrosis and fibroelastosis.
- 4.
Computed tomography (CT) scans show high-resolution definition of coronary artery anatomy.
- 5.
Cardiac troponin I level may be increased.
C. Management
Medical treatment alone carries a very high mortality (80% to 100%). All patients with this diagnosis need surgery.
- 1.
Palliative surgery (simple ligation of the anomalous LCA close to its origin from the PA) may be performed in very sick infants to prevent steal into the PA. This should be followed later by an elective bypass procedure.
- 2.
Most centers prefer definitive surgery unless the patient is critically ill, but the optimal operation remains controversial. One of the following two-coronary system surgeries may be performed.
- a.
Intrapulmonary tunnel operation (Takeuchi repair). Initially a 5- to 6-mm AP window is created between the ascending aorta and the MPA at the level of the takeoff of the LCA. In the posterior wall of the MPA, a tunnel is created that connects the opening of the AP window and the orifice of the anomalous LCA. The mortality rate is near 0%, but a rate as high as over 20% has been reported. Late complications of the procedure include supravalvar PA stenosis by the tunnel (75%), baffle leak (52%) causing coronary-PA fistula, and AR.
- b.
LCA implantation. In this procedure, the anomalous coronary artery is excised from the PA along with a button of PA wall, and the artery is reimplanted into the anterior aspect of the ascending aorta. The early surgical mortality rate is 15% to 20%.
- c.
Tashiro repair. A narrow cuff of the main PA, including the orifice of the LCA, is transected. The upper and lower edges of the cuff are closed to form a new left main coronary artery, which is anastomosed to the aorta. The divided main PA is anastomosed end-to-end.
- d.
Subclavian-to-LCA anastomosis. In this technique, the end of the left subclavian artery is turned down and anastomosed end-to-side to the anomalous LCA.
- a.
II. Aortopulmonary Septal Defect
A. Pathology and Pathophysiology
In aortopulmonary septal defect (also known as aortopulmonary [AP] window), a large defect is present between the ascending aorta and the main PA. This condition results from failure of the spiral septum to completely divide the embryonic truncus arteriosus. Unlike persistent truncus arteriosus, two separate semilunar valves are present in this condition.
B. Clinical Manifestations
- 1.
Clinical manifestations are similar to those of persistent truncus arteriosus and are more severe than those of PDA. CHF and pulmonary hypertension appear in early infancy. Peripheral pulses are bounding, but the heart murmur is usually of the systolic ejection type (rather than continuous murmur) at the base.
- 2.
The natural history of this defect is similar to that of a large untreated PDA, with development of pulmonary vascular obstructive disease in surviving patients.
C. Management
Prompt surgical closure of the defect under CPB is indicated. The surgical mortality rate is very low.
III. Arteriovenous Fistula, Coronary
A. Pathology and Pathophysiology
Coronary artery fistulas occur in one of two patterns:
- 1.
True coronary arteriovenous fistula. It represents a branching tributary from a coronary artery coursing along a normal anatomic distribution, with blood emptying into the coronary sinus. This type occurs in only 7% of patients.
- 2.
Coronary artery fistula. In most patients the fistula is the result of an abnormal coronary artery system with aberrant termination. In most cases the fistula terminates in the right side of the heart and the PA (40% in the RV, 25% in the RA, and 20% in the PA).
B. Clinical Manifestations
- 1.
The patient is usually asymptomatic. A continuous murmur similar to the murmur of PDA is audible over the precordium.
- 2.
The ECG is usually normal, but it may show T-wave inversion, RVH, or LVH if the fistula is large. Myocardial infarction pattern can occur. Chest radiographs usually show normal heart size.
- 3.
Echo studies usually suggest the site and type of the fistula. Presence of a massively dilated proximal portion of one coronary artery suggests a coronary artery fistula or an arteriovenous fistula. One can follow the course of the dilated coronary artery to its site of entry.
- 4.
Often selective coronary artery angiography is necessary for accurate diagnosis before intended intervention.
C. Management
- 1.
A tiny coronary artery fistula to the main PA (coronary artery-to-PA fistula) that is detected incidentally by an echo study should be left alone. Spontaneous closure may occur in some small fistulae, but some of them may progress and require intervention.
- 2.
Small fistulous connections in the asymptomatic patient may be monitored.
- 3.
For moderate or large coronary artery fistula, transcatheter occlusion is reasonable using coils or other occluding devices.
- 4.
Elective surgery is indicated if not amenable to catheter occlusion. Using CPB, the fistula is ligated as proximally as possible without jeopardizing flow in the normal arteries and also ligated near its entrance to the cardiac chamber. The surgical mortality rate is zero to 5%.
IV. Arteriovenous Fistula, Pulmonary
A. Pathology and Pathophysiology
- 1.
There is direct communication between the PAs and pulmonary veins (PVs), bypassing the pulmonary capillary circulation. It may take the form of either multiple tiny angiomas (telangiectasis) or a large PA-to-PV communication.
- 2.
About 60% of patients with pulmonary AV fistulas have Osler-Weber-Rendu syndrome. Rarely, chronic liver disease or a previous bidirectional Glenn operation may cause the fistula.
B. Clinical Manifestations
- 1.
Cyanosis and clubbing are present, with a varying degree of arterial desaturation ranging from 50% to 85%. Polycythemia is usually present. A faint systolic or continuous murmur may be audible over the affected area. The peripheral pulses are not bounding.
- 2.
Chest radiographs show normal heart size (unlike systemic AV fistula). One or more rounded opacities of variable size may be present in the lung fields. The electrocardiogram (ECG) is usually normal.
- 3.
The diagnosis can be made through contrast two-dimensional (2D) echo. In this technique, 4 to 10 mL of saline that has been agitated is injected into a peripheral vein while monitoring the appearance of bubbles in the left atrium.
- 4.
CT typically shows one or more enlarged arteries feeding a serpiginous or lobulated mass, and one or more draining veins. Pulmonary angiography remains the gold standard to determine the position and structure of the fistula prior to intervention.
- 5.
Stroke, brain abscess, and rupture of the fistula with hemoptysis or hemothorax are possible complications.
C. Management
- 1.
Transcatheter occlusion is recommended for all symptomatic patients and for asymptomatic patients with discrete lesions with feeding arteries ≥3 mm in diameter.
- 2.
Diffuse microscopic pulmonary AV malformations are not amenable to transcatheter occlusion. Surgical resection of the lesions, with preservation of as much healthy lung tissue as possible, may be attempted in symptomatic children, but the progressive nature of the disorder calls for a conservative approach.
V. Arteriovenous Fistula, Systemic
A. Pathology and Pathophysiology
- 1.
Systemic AV fistulas may be limited to small cavernous hemangiomas or may be extensive. In large AV fistulas, there is direct communication (either a vascular channel or angiomas) between the artery and a vein without the interposition of the capillary bed.
- 2.
The two most common sites of large systemic AV fistulas are the brain and liver.
- a.
In the brain, it is usually a large type occurring in newborns in association with a vein of Galan malformation.
- b.
In the liver, hemangioendotheliomas (densely vascular benign tumors) are more common than fistulous arteriovenous malformation.
- a.
- 3.
In the large type, cardiomegaly, tachycardia, and even CHF may result because of decreased peripheral vascular resistance and increased stroke volume.
B. Clinical Manifestations
- 1.
A systolic or continuous murmur is audible over the affected organ. The peripheral pulses may be bounding. A gallop rhythm may be present with CHF.
- 2.
Chest radiographs show cardiomegaly and increased PVMs. The ECG may show hypertrophy of either or both ventricles.
C. Management
- 1.
In patients with large cerebral AV fistulas (and CHF), surgical ligation of the affected artery to the brain is rarely possible without infarcting the brain. Many of these infants die in the neonatal period.
- 2.
In hepatic fistulas, surgical treatment is often impossible because they are widespread throughout the liver. However, hemangioendotheliomas often disappear completely.
- a.
Large liver hemangiomas have been treated with corticosteroids, aminocaproic acid, local radiation, or partial embolization, but the beneficial effects of these management options are not fully established.
- b.
Catheter embolization is becoming the treatment of choice for many symptomatic patients with hepatic AV fistula.
- a.
VI. Cor Triatriatum
In this rare cardiac anomaly, the LA is divided into two compartments by a fibromuscular septum with a small opening, producing obstruction of pulmonary venous (PV) return. Embryologically, the upper compartment is a dilated common PV and the lower compartment is the true LA. Hemodynamic abnormalities of this condition are similar to those of MS in that both conditions produce pulmonary venous and arterial hypertensions.
- 1.
Important physical findings include dyspnea, basal pulmonary crackles, a loud P2, and a nonspecific systolic murmur. The ECG shows RVH, and occasional RAH. Chest radiographs show evidence of pulmonary venous congestion or pulmonary edema, prominent MPA segment, and right-sided heart enlargement. Two-dimensional echo is diagnostic. It demonstrates a linear structure within the LA cavity. Degree of obstruction and pulmonary hypertension can be easily estimated by echo study.
- 2.
This is a curable form of pulmonary hypertension. Surgical correction is always indicated. Pulmonary hypertension regresses rapidly in survivors if the correction is made early.
VII. Dextrocardia and Mesocardia
The terms dextrocardia (heart in the right side of the chest) and mesocardia (heart in midline of the thorax) express the position of the heart as a whole but do not specify the segmental relationship of the heart. A normally formed heart can be in the right chest because of extracardiac abnormalities. On the other hand, a heart in the right chest may be a sign of a serious cyanotic heart defect. The segmental approach is used to examine the significance of abnormal position of the heart.
A. The Segmental Approach
The heart and the great arteries can be viewed as three separate segments: the atria, the ventricles, and the great arteries. These three segments can vary from their normal positions either independently or together, resulting in many possible sets of abnormalities. Accurate mapping can be accomplished by echo and angiocardiography, but chest radiographs and ECG are helpful also.
- 1.
Localization of the atria.
- a.
Chest radiographs
- (1)
Right-sided liver shadow and left-sided stomach bubble indicate situs solitus of the atria. Left-sided liver shadow and right-sided stomach bubble indicate situs inversus of the atria.
- (2)
A midline (symmetrical) liver shadow on chest radiograph suggests heterotaxia.
- (1)
- b.
The ECG: The sinoatrial (SA) node is always located in the RA. Therefore the P axis of the ECG can be used to locate the atria.
- (1)
When the P axis is in the 0 to +90 degrees quadrant, situs solitus of the atria is present.
- (2)
When the P axis is in the +90 to +180 degrees quadrant, situs inversus of the atria is present.
- (1)
- c.
Two-dimensional echo identifies the IVC and/or pulmonary veins. The atrial chamber that is connected to the IVC is the RA. The morphology of the atrial appendages further helps differentiate the atria, with the right atrial appendage being broad and triangular and left atrial appendage being narrow and fingerlike. Cardiac magnetic resonance imaging (MRI), angiocardiography, and surgical inspection aid further in the diagnosis of atrial situs.
- a.
- 2.
Localization of the ventricles . Ventricular localization can be accomplished by the ECG and 2D echo.
- a.
ECG: The depolarization of the ventricular septum normally takes place from the embryonic LV to the RV, producing Q waves in the precordial leads that lie over the anatomic LV.
- (1)
If Q waves are present in V5 and V6 but not in V1, D-Loop of the ventricle (as in normal persons) is likely.
- (2)
If Q waves are present in V4R, V1, and V2 but not in V5 and V6, L-loop of the ventricles is likely (ventricular inversion, as seen in L-TGA).
- (1)
- b.
Two-dimensional echo: The tricuspid valve leaflet inserts on the interventricular septum more toward the apex than does the mitral septal leaflet.
- (1)
The ventricle that is attached to the tricuspid valve is the RV.
- (2)
The ventricle that has two papillary muscles is the LV.
- (3)
Furthermore, the trabeculations in the RV are more coarse, and the LV endocardial surface is more smooth.
- (1)
- 3.
Localization of the great arteries . Echo studies can locate the great arteries accurately, but the ECG is not helpful in finding them.
- a.
B. Common Types of Displacement
The four most common types of dextrocardia are (1) classic mirror-image dextrocardia, (2) normal heart displaced to the right side of the chest, (3) congenitally corrected TGA, and (4) mal-differentiated ventricle such as seen with asplenia or polysplenia syndrome ( Fig. 10.1 ). All these abnormalities may result in mesocardia. Echo study can make accurate diagnosis of the segmental relationship in dextrocardia or mesocardia. However, chest radiographs and ECGs can be used to deduce the nature of segmental abnormalities, as described earlier.
- 1.
Classic mirror-image dextrocardia ( Fig. 10.1A ) shows left-sided liver shadow on chest radiographs. The ECG shows the P axis between +90 and +180 degrees and the Q waves in V5R and V6R.
- 2.
Normally formed heart shifted toward the right side of the chest (dextroversion) ( Fig. 10.1B ) shows the liver shadow on the right on chest radiographs, the P axis between 0 and +90 degrees, and the Q waves in V5 and V6 on the ECG.
- 3.
Congenitally corrected L-TGA ( Fig. 10.1C ) shows situs solitus of abdominal viscera on chest radiographs. The ECG shows the P axis in the normal quadrant (0 to +90 degrees) and the Q waves on the right precordial leads (V3R, V1, or V2) but no Q waves on V5 and V6.
- 4.
Undifferentiated cardiac chambers ( Fig. 10.1D ) are often associated with heterotaxia (with complicated cardiovascular defects) and may show midline liver on chest radiographs. The ECG may show the P axis shifting between the 0 to +90 degree quadrant and +90 to +180 degree quadrant in asplenia syndrome (with two sinus nodes). In polysplenia syndrome, the P axis may be superiorly directed (due to ectopic atrial pacemaker). Abnormal Q waves may be seen in the precordial leads.
