Congenital Heart Disease



Congenital Heart Disease





SECTION 1 ECHOCARDIOGRAPHY AND CONGENITAL HEART DISEASE

Progress has been made in the diagnosis of congenital heart diseases. In the past, careful physical examination along with the electrocardiogram and the chest x-ray was the mainstay of making a preliminary diagnosis. Once this assessment was made, cardiac catheterization, hemodynamics, angiography, and analysis of complex catheter courses laid the groundwork for the cardiac surgeon.

Currently, echocardiographic techniques allow for the precise diagnosis of congenital heart diseases. This includes the location of shunts, great vessel arrangements, atrioventricular valve orientations, and many other abnormalities, all of which can be displayed on the echo screen in both two and three dimensions. Doppler assessments allow for pressure and flow calculations and shunt quantifications. Echocardiography along with CMRI have revealed so much anatomic
and physiologic information that cardiac catheterization with angiography have become focused on gathering information that is missing from the diagnostic equation.

Structural heart interventions with devices for shunt closure and valve replacement have filled in the time slots in the diagnostic cardiac catheterization laboratories and have altered the procedures done by cardiac surgeons.

The specialty of adult congenital cardiology has been born from the excellent work done by pediatric cardiologists, pediatric cardiac surgeons, and adult cardiologists interested in this area, and they have allowed our patients to reach adulthood and lead normal lives.

This chapter deals with the diagnosis of congenital heart disease focusing on common, relative simple abnormalities and not dealing with very complex congenital cardiac abnormalities. For the emergency room physician, the primary care physician, and the internist to the cardiologist, the diagnosis of congenital heart disease in the adult patient is challenging. There are certain basic clues in the general examination, the electrocardiogram, and the echocardiogram that should allow the correct diagnosis to be made.

Bicuspid aortic valve is the most common congenital abnormality of the heart, and it is presented in more detail in the section on the aortic valve and aorta.

Examples of common congenital abnormalities in the young person and adult are discussed in the following pages.


SECTION 2 PATENT FORAMEN OVALE

Although bicuspid aortic valve is the most common congenital abnormality of the heart if we label patent foramen oval (PFO) as a congenital abnormality, it might be the most common. Actually, we consider PFO to be a part of our development that is incomplete and not a frank defect. In ordinary circumstances, it poses no problem, but in special situations, it can cause difficulty. In the setting of high right-sided pressures with pulmonary embolus or pulmonary hypertension from another etiology, high right atrial pressures will result in a PFO opening up and allowing right-to-left shunting. In the setting of a PFO with a relative short tunnel, simple maneuvers such as deep breathing, coughing, sneezing, and Valsalva maneuver can open the PFO and cause right-to-left shunting. This physiology comes into play in the setting of SCUBA diving when decompression difficulties occur.1

PFO at times can be a major factor in cryptogenic stroke. Small thrombi from the legs can migrate up the vena cava to the right atrium and in the right clinical setting can cross to the arterial circulation. The extreme of this situation is the pulmonary embolus in transit that crosses to the left circulation and causes a stroke. An additional relationship exists with PFO and migraine headaches. The incidence of migraine headaches in those who have a PFO is higher than in
the general population. One explanation is that vasoactive substances bypass the lungs by crossing through the PFO producing migraine headaches by altering the vasculature of the brain.2,3,4


LARGE PATENT FORAMEN OVALE






FIGURE 10.1 A freeze frame from the image above that shows the thin portion of the interatrial septum on inspiration as it shifts to the left side (yellow arrow) opening up the tunnel of the PFO (green arrow).






FIGURE 10.2 “Bubble study” showing a negative stream coming from the left side and then with inspiration a puff of contrast crosses from right to left. TEE, 89° view.



SECTION 3 ATRIAL SEPTAL DEFECT


OSTIUM SECUNDUM ATRIAL SEPTAL DEFECT

Ostium secundum atrial septal defects (ASDs) are the most common type of ASD. Embryologically, this defect occurs when the septum secundum does not completely cover the fenestration in the septum primum. ASDs can be of various sizes and shapes and can be multiple or can be like “Swiss cheese.” They result in left-to-right shunting because of the low resistance pathway to the compliant right atrium and ventricle, and this will remain so unless the complication of pulmonary hypertension develops.

Individuals with this defect may go unrecognized until adulthood. Careful history taking will often reveal intolerance to vigorous exercise, but they are usually participants. Pregnancy is usually tolerated well unless pulmonary hypertension is present. Physical examination may not be so revealing unless careful attention is directed to the second sound uncovering fixed splitting. There may be an ejection murmur at the left upper sternal border from excessive flow.

The electrocardiogram is usually not normal and shows incomplete right bundlebranch block. In older individuals with larger ASDs, the chronic volume overload of the right atrium and ventricle results in dilated chambers and atrial fibrillation.

The echocardiogram plays a major role in making this diagnosis and defining the anatomy and physiology. The location of the defect and its relationship to the aorta and the superior and inferior vena cava and the direction and quantification of the shunt can be determined. Current therapies of these defects with closure devices all require exact definition of the size of the defect, the anatomy of the remaining interatrial septum, and the relationship to the adjacent aorta. The definition of the aortic rim is important to anchor the edges of the implanted device.5

Examples of secundum atrial septal defects are noted in Figures 10.3 and 10.4.






FIGURE 10.3 Flow through the secundum ASD (blue on color Doppler with aliasing in the middle of the jet).







FIGURE 10.4 3D view of the defect from the left side (black arrow).


TEE-GUIDED CLOSURE OF A SECUNDUM ASD WITH AN AMPLATZER DEVICE






FIGURE 10.5 TEE 42° view showing the defect in the atrial septum and the aortic rim—which should be at least 5 mm in order to minimize complications.







FIGURE 10.6 Once both disks are out from the guiding catheter, they assume their original shape and close on the defect.


COMPLICATIONS OF SECUNDUM ATRIAL SEPTAL DEFECT

If ASD escapes detection in childhood, in later life it may surface because of a complication. The most dreaded complication of these defects is the development of increased pulmonary vascular resistance and pulmonary hypertension. This complication can be progressive to the point of shunt reversal and the development of cyanosis. ASD, ventricular septal defect, and patent ductus arteriosus are the three congenital abnormalities that most commonly result in shunt reversal. The presence of one of these defects, a reversed shunt and cyanosis, forms the components of Eisenmenger syndrome.

Actually, Eisenmenger in 1897 first described the syndrome of the presence of a shunt, reversed flow, and cyanosis in an individual with a ventricular septal defect. Currently, this terminology is used for any shunt that results in increased pulmonary vascular resistance and shunt reversal with cyanosis.6,7

In addition to pulmonary hypertension, chronic volume overload of the right atrium and ventricle can lead to dilated dysfunctional chambers, right heart failure, ascites, and atrial fibrillation. In this setting, the presence of right heart failure,ascites and incomplete right bundle-branch block are clues to the diagnosis. Echocardiography will usually solve the problem.



SECTION 4 VENTRICULAR SEPTAL DEFECT

Congenital ventricular septal defect comes in many forms including muscular defects, inflow defects, and outflow defects both infracristal and supracristal. Defects in the inflow area of the right ventricle are very close to the tricuspid valve and the perimembranous area of the ventricles. The septal leaflet of the tricuspid valve often has its origin in the middle of the membranous portion of the interventricular septum and poses options for shunting to take place. Below the tricuspid valve, the shunt is to the right ventricle, and above the septal leaflet, it is directed to the right atrium (Gerbode defect). Muscular defects can be of various locations and can be multiple often orienting around the moderator band.

Other defects in the direction of the right and left ventricular outflow tracts may be infracristal or supracristal. The infracristal defects are identified as their jets relate to the aortic valve and are located at the 9 o’clock region or more toward the body of the right ventricle. The supracristal defects are high up in the interventricular septum and have a 12 o’clock orientation as related to the aorta in cross section and lie under the right cusp of the aortic valve. These defects are notorious for resulting in poor support of the right coronary cusp of the aortic valve and can cause aortic regurgitation of various degrees. Repair of this defect often requires intervention of one type or another on the aortic valve. The resulting aortic regurgitation may change in an abrupt fashion, and for this reason, long-term follow-up is needed. These types of defects do not lend themselves to percutaneous interventions.8,9

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May 5, 2019 | Posted by in CARDIOLOGY | Comments Off on Congenital Heart Disease
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