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Congenital Heart Disease in Adults
     

Anomalies of the Great Veins

Due to major advances in both diagnosis and treatment of congenital heart disease in children, many are living into adulthood. There are almost one million such patients this year.

Congenital heart disease can be divided into two types:

1. The acyanotic ones in which the oxygen level in the blood is high enough to keep the patients' color pink;

2. The cyanotic ones in which the oxygen level in the blood is low enough for the lips and skin to show varying degrees of bluish discoloration.

1. Acyanotic congenital heart consist of the following:

a) atrial septal defect ( figures 112a, 112b )
b) ventricular septal defect ( figure 112c )
c) patent ductus arteriosus ( figure 22 )
d) aortic stenosis ( figures 24a, 24b, 46a, 46b, 46c, 47 )
e) pulmonary stenosis ( figure 25a, 25b )

f) parachute mitral valve ( figures 44g-1 and 44g-2 )
g) coronary artery fistula
h) anomalies of the great veins

 

2. Cyanotic Congenital Heart
Disease
features bluish discoloration of the skin and lips as opposed to the normal pink appearance. The cyanosis is due to the shunting of systemic venous blood to the arterial circulation causing arterial blood desaturation of oxygen. The size of the shunt determines the degree of desaturation. In adults the most common causes of cyanotic congenital heart disease are tetralogy of Fallot and Eisenmenger's syndrome.

a) Tetralogy of Fallot ( figure 23d )
b) Ebstein's Anomaly ( figure 23e )
c) Transposition of the Great Arteries ( figure 23h )
d ) Eisenmenger's syndrome ( figure 23j )

Brickner,M.E. and others,Congenital Heart Disease in Adults,N.Engl.J.Med.,Vol.342.N4,2000,pp.334-342

 

Anomalies of the Great Veins

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Introduction
Anomalies of the Systemic Veins
Anomalies of the Pulmonary Veins
Anomalies of the Coronary Sinus


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Introduction
In the normal heart, the superior and inferior vena cavea, along with the coronary sinus, have a characteristic arrangement within the right atrium. It is therefore appropriate to consider abnormalities of each channel separately, recognizing that, in rare cases, these anomalies may coexist.

Anomalies of the systemic veins are not uncommon, examples of which include a persistent left superior vena cava connected to the coronary sinus, interrupted inferior vena cava, and absent right superior vena cava.

Anomalies of the systemic veins are associated with atrial isomerism, an understanding of which is important in sorting out the various lesions involved. These so-called heterotaxic syndromes are characterized by failure of many "right-left" differentiation, leading to ambiguity in viscero-atrial situs, along with anomalies of systemic or pulmonary venous return.

In patients with left atrial isomerism, the infrahepatic portion of the inferior vena cava is frequently absent, and the venous return from the lower part of the body enters the superior vena cava via the azygos vein. In patients with right atrial isomerism, the right and left hepatic veins may enter the ipsilateral sides of the common atrium, remaining separate from the inferior vena caval entrance.

Abnormalities of the pulmonary veins are also common in both left and right atrial isomerism; direct connection to the superior or inferior vena cava is more frequent in right atrial isomerism, whereas anomalous pulmonary venous drainage into the same side of the atrium as the systemic venous drainage is more frequent in left atrial isomerism. Frequently there is outflow obstruction to pulmonary arterial blood flow at either the valvar or subvalvar level. Pulmonary atresia is more common with right atrial isomerism, whereas pulmonary stenosis is more common in left atrial isomerism. Pulmonary artery anomalies are not rare, particularly when there is pulmonary atresia with the ductus arteriosus as the only source of pulmonary blood flow. After the ductus closes, a "coarctation" commonly develops in the pulmonary artery just at the insertion of the ductus. The branching pattern of the pulmonary arteries generally assumes one of two forms, depending on whether left or right atrial isomerism is present.

In right atrial isomerism, both right and left pulmonary arteries tend to look like a normal right pulmonary artery, with the bronchus for the upper lobe being above the first segmental artery for the right upper lobe (eparterial bronchus).

In contrast, in left atrial isomerism, the bronchi are below the pulmonary artery at the hilum (hyparterial bronchi), as is the case for a normal left pulmonary artery. In right atrial isomerism, both lungs tend to be trilobed, whereas in left atrial isomerism both lungs tend to be bilobed.

Finally, asplenia is more commonly present in right atrial isomerism, whereas polysplenia is more frequently associated with left atrial isomerism. These features have contributed to the general rule (which has many exceptions) that patients with right atrial isomerism tend to have bilateral "right-sidedness", whereas those with left atrial isomerism tend to have bilateral "left-sidedness".


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Anomalies of the Systemic Veins


This discussion in limited to anomalies of the great systemic veins, which include the superior and inferior vena cava, along with the coronary sinus.

Anomalies of the superior vena cava

A persistent left superior vena cava is the most common form of anomalous venous drainage involving the superior vena cava and represents persistence of the left horn of the embryonic sinus venosus, which normally involutes during normal development to become the coronary sinus. Almost always, a persistent left superior vena cava enters the right atrium through the orifice of an enlarged coronary sinus. To this extent, therefore, the lesion is considered to be an anomaly of the coronary sinus. It characteristically reaches the heart in the angle between the left atrial appendage and the left pulmonary veins. The left superior vena cava then runs down the back of the left atrium to enter the left atrioventricular groove and channel draining blood from the head and both arms. This is the site in the normal heart of the oblique ligament and vein of Marshall.

A persistent left superior vena cava is of no clinical significance since the systemic venous blood continues to return to the right atrium, but may be troublesome in keeping blood out of the field during cardiopulmonary bypass. It may be ligated only in the presence of a communicating vein between the right and left superior vena cavea. In some circumstances, the left vena cava may be the only channel draining the head and both arms, and the usual right superior vena cava is absent.

Rarely, a persistent left superior vena cava can be connected to the roof of the left atrium between the left atrial appendage and pulmonary veins rather than to the coronary sinus. This anomaly is termed complete unroofing of the coronary sinus. The orifice of the coronary sinus then persists as an interatrial communication. A levo-atrial cardinal vein is a rare venous structure that is found in association with the hypoplastic left heart syndrome. It provides the only route of exit for pulmonary venous return, and typically runs along the roof of the left atrium, from the anticipated site of a left superior vena cava, to the left brachiocephalic vein, and the superior vena cava.

Other rare anomalies of the superior vena cava include a right superior vena cava connected to left atrium, and a right superior vena cava connecting with both the right and left atria through separate orifices in the presence of an intact atrial septum. Aneurysmal dilatation of the superior vena cava is recognized as being an acquired lesion of the heart and is rarely seen in children.

Anomalies of the inferior vena cava

Anomalies of the inferior vena cava are most commonly an integral constituent of atrial isomerism, and only rarely is found in patients with usual or mirror-image atrial arrangements. The most common lesion of the inferior vena cava is that of interruption of the abdominal portion, with continuation through either the azygos or the hemiazygos veins. Described simply as ‘azygos continuation’, it is important to always exclude the existence of left atrial isomerism, which is performed through the identification of the bronchial morphology and determination of the presence of polysplenia. When there is interruption of the inferior vena cava with azygos continuation, all the systemic venous return reaches the morphologically right atrium through a superior vena cava. With azygos continuation, this is the right-sided vein, whereas with hemiazygos continuation, the inferior caval blood is returned through a persistent left superior vena cava.

Anomalies of the coronary sinus


Morphology
The most frequent morphological anomaly of the coronary sinus is persistence of a left superior vena cava which drains through the orifice of the coronary sinus. Under these circumstances, the coronary sinus is enlarged, and the lesion is of no clinical importance. An unroofed coronary sinus, however, can produce windows into the left atrium and provide right-to-left intraatrial shunting. The extreme form of this lesion is completely unroofed coronary sinus, in which the interatrial communication is at the mouth of the sinus. Isolated coronary sinus windows can occur, however, when there is no persistent left superior vena cava and when the atrial septum is intact.

Other rare reported anomalies of the coronary sinus include connection of hepatic veins to the coronary sinus, fistulous connections between the coronary sinus and the coronary arteries, and connection of the coronary sinus to the inferior vena cava.

The unroofed coronary sinus syndrome consists of total absence of the coronary sinus, as there is absence of the partition between the coronary sinus and the left atrium. Individual coronary veins drain separately into both the right and left atria. The unroofed coronary sinus syndrome with persistent left superior vena cava occurs when part or all of the common wall between the coronary sinus and the left atrium is absent, and there is a persistent left superior vena cava. The persistent superior vena cava usually connects to the left upper corner of the left atrium between the attachment of the left atrial appendage and the left pulmonary veins.

There is often an associated coronary sinus ASD, which may be further complicated by a confluent partial or complete atrioventricular septal defect. Other associated lesions include a patent foramen ovale, ostium secundum ASD, tricuspid atresia, tetralogy of Fallot, and atrial isomerism. Of considerable importance is that the innominate vein is absent in the great majority of cases, and the right superior vena cava is frequently small or absent. The inferior vena cava may cross to the left side below the diaphragm and enters the left hemiazygos vein, which subsequently drains into the left superior vena cava. The hepatic veins usually enter the inferior aspect of the right atrium, but they too may connect anomalously to the inferior left atrial wall.

Hemodynamics
Isolated completely unroofed coronary sinus is associated with a small right-to-left shunt and is usually of no hemodynamic consequence. In the presence of a persistent left superior vena cava, however, cyanosis may be mild or severe depending on the degree of right-to-left shunting.

Clinical Findings & Management


Patients with completely unroofed coronary sinus and persistent left superior vena cava present with cyanosis. Cerebral embolization and cerebral abscess may also complicate the clinical picture. The diagnosis of unroofed coronary sinus syndrome is usually made by echocardiography. Cineangiography may be useful in defining a persistent left superior vena cava and/or inferior vena cava drainage to the left atrium, in addition to defining commonly associated abnormalities.

Medical management is usually expectant, and operative correction is usually indicated.

Isolated coronary sinus ASD (isolated unroofed coronary sinus without persistent left superior vena cava) is treated the same as other types of ASD. Unroofed coronary sinus with persistent left superior vena cava is approached with the goal of separating the systemic from pulmonary venous drainage. The most direct method is to resect much of the atrial septum, leaving a rim of limbus to preserve the conduction system, then separate the three systemic veins from the four pulmonary veins by means of a pericardial patch. Left superior vena cava ligation can be safely done if there is a patent crossing vein connecting the right and left superior vena cavea. A final alternative is to anastomose the left superior vena cava directly to the left pulmonary artery, although the experience with this method is limited. When unroofed coronary sinus is associated with other major cardiac anomalies, the associated anomaly usually presents a clear indication for operation.

RIGHT VENTRICULAR HYPERTROPHY IN CONGENITAL HEART DISEASE AND DIFFERENTIAL

Some of the causes of right ventricular hypertrophy include congenital heart disease (there are acquired causes as well:see below) such as the following:

A.Triology of Fallot
Triology of Fallot is composed of:

1. Pulmonary artery stenosis (valvular)

2. Right ventricular hypertrophy (increased thickness of the right ventricular walls)

3. Atrial septal defect (hole in the atrial septum).

Diagnosis can be established by

Doppler echocardiography.

DD of congenital heart diseases related to right ventricular hypertrophy

A. Cyanotic heart disease (in which the patient has a bluish discoloration due to decreased oxygen leve from shunting of desaturated blood from the right side of the heart to the leftl through anabnormal hole inthe the heart or its great vessels):
1. with right ventricular hypertrophy: Tetralogy of Fallot with pulmonary stenosis (narrowing of the opening of the great vessel carrying unoxygenated blood to the lungs from the right ventricle), ventricular septal defect(hole in the lower partition separating the right ventricle from the left, "IVS"), over-riding of the aorta (the great vessel leading out of the heart carrying the oxygenated blood over the interventricular septum("IVS") to the rest of the body from the left ventricle); Eisenmenger syndrome(see above under cyanotic heaertdisease).

B. Non-cyanotic heart disease:
1. with right ventricular hypertrophy: ASD(hole in the atrial septum), pulmonary stenosis(narrowing of the pulmonary artery,which receives blood from the right ventricle ,sending to it to the lungs for oyxgenation).


Diagnosed by doppler echocardiography and MRI

Differential diagnosis

The right ventricular hypertrophy(increased thickness of the right ventricle) can be due to congenital or acquired causes like an atrial septal defect(congenital)and mitral stenosis from rheumatic fever fro example.

The Abnormal Ventricular Electrocardiogram (ECG) (see figures illustrations 1 and 2)

Illustration figure 6.22
The difference between the electrocardiographic abnormalities produced by congenital heart disease, such as pulmonary valve stenosis (A), and those produced by the early stages of acquired disease, such as mitral stenosis (B).

 

Illustration figure 6.23
Hypothetical explanation for the electrocardiographic abnormalities caused by systolic pressure overload of the right ventricle.


The Mean T Vector and Right Ventricular Hypertrophy

Diastolic pressure(filling period)overload of the right ventricle should theoretically produce a mean T vector that is larger than average, and the ST segment vector should be parallel to the mean T vector.

Actually, the most common cause of diastolic (filling period) overload of the right ventricle is a secundum atrial septal defect (a hole in the upper partition of the heart, the atrium) in which a right ventricular conduction defect dominates the electrocardiogram. The T wave abnormality in such a patient is secondary to the QRS abnormality, and the latter dominates the electrocardiogram rather than abnormalities associated with right ventricular diastolic pressure overload.

Systolic pressure (when the ventriles are squeezig down to contract) overload of the right ventricle, due to congenital heart disease, such as pulmonary valve stenosis, tetralogy of Fallot, or the Eisenmenger syndrome, produces a mean QRS vector that is directed to the right and anteriorly. Therefore, the mean T vector will be located 150° to 180° away from the mean QRS vector and will be directed leftward and posteriorly (Fig. 6.22, figure 1 lnk attached).

The transmyocardial pressure gradient of the right ventricle is decreased and finally eliminated by the abnormal systolic pressure generated during the late stage of mechanical ventricular systole. This permits the repolarization process to begin in the endocardium of the right ventricle, producing electrical forces that are opposite normal (Fig. 6.23 ,fgfure 2attached separately). A right atrial abnormality is often present.


Figure 6.22 The difference between the electrocardiographic abnormalities produced by congenital heart disease, such as pulmonary valve stenosis (A), and those produced by the early stages of acquired disease, such as mitral stenosis (B).

A. The duration of the QRS complex is 0.10 second or less. The mean QRS vector is directed to the right and anteriorly, and the ST and T vectors are directed opposite the mean QRS vector. This type of abnormality occurs with congenital disease, such as pulmonary valve stenosis, or advanced acquired disease, such as mitral stenosis with moderately severe pulmonary hypertension. A right atrial abnormality may be apparent in patients with right ventricular hypertension.

B. The duration of the QRS complex is 0.10 second or less, and the mean QRS vector is located vertically and posteriorly. The mean T vector may be directed to the left and slightly posteriorly. This type of mean QRS vector is often caused by acquired disease. A left atrial abnormality as shown here suggests an early stage of mitral stenosis.

Figure 6.23 Hypothetical explanation for the electrocardiographic abnormalities caused by systolic pressure overload of the right ventricle.


A. Electrical forces and QRS and T deflections of a hypothetical cell that has been stimulated on the left side.

B. Electrical forces and QRS and T deflections produced when a hypothetical cell has been cooled but also stimulated on the left side.

C. Normal depolarization and repolarization of the ventricular wall of a normal adult. The endocardial systolic pressure is greatest in the endocardial area as compared to the epicardial area. Both the QRS complex and T wave are upright.

D. Systolic pressure overload of the right ventricle. The systolic pressure is so great that there is no significant difference between the endocardial and epicardial pressure. The QRS vector will be directed to the right and the mean T vector will be directed to the left.


Early in the natural history of right ventricular hypertrophy due to acquired heart disease, such as mitral stenosis or primary pulmonary hypertension, the mean QRS vector tends to have an intermediate or vertical direction; it usually retains a slightly posterior direction. The mean T vector tends to be directed leftward and posteriorly (Fig. 6.22 figure 1 illustratio). A left atrial abnormality may be present with mitral stenosis, and a right atrial abnormality may occur with pulmonary hypertension.

Later in the course of disease, as more severe right ventricular hypertension develops, the mean QRS vector tends to be directed more to the right and anteriorly, and the mean T vector eventually lies 150° to 180° away from the mean QRS vector, being directed to the left and posteriorly. The mean ST vector tends to be parallel with the mean T vector.