1. Accomisural artic valve
2. Miniature valve ring
3. Bicuspid aortic valve where the malformation does not necessarily mean that the patient will have aortic stenosis but a large percentage of these patients present with a marked tendency to develop calcification and rigidity at the valve level, which in turn favors the development of aortic valvular stenosis. This is by far the most common congenital disease of the heart and great arteries.
4. Monocuspid aortic valve where the aortic valve is only formed by membrane interrupted by commissure in one side of the aorta. This second category of aortic valve malformation usually signifies a severe stenosis, present since birth.
5. Quadricuspid valve
6. Six cuspid valve

1. Left ventricular hypertrophy of the concentric type with thicker than normal left ventricular walls and intraventricular septum and small left ventricular chamber. In turn, and in the last stage of the disease, left ventricular hypertrophy can be observed with dilatation of the left ventricular chamber.

    Left ventricular hypertrophy is a common finding in these patients.
    Endocardial fibroelastosis can be seen particularly in children. Occasionally endocardiac fibroelastosis can be associated with hypoplasia of the left ventricular wall. In these cases the aortic stenosis is of secondary importance.
    Patent foramen ovale can be seen occasionally as a consequence of the large increase in the left ventricular and diastolic pressure transmitted to the left atrium, with development of a left to right cardiac shunt.
    Post stenotic dilatation of the aortic arch is prevalent in adults and young children as compared with newborn and young children.
    Other different malformations can be seen in association to congenital valvular aortic stenosis. The most frequent of those is patent ductus arteriosus and coarctation of the aorta.
    One of the most typical features of congenital aortic stenosis, as compared with another etiology of AS, is the early appearance of calcification. More than 80% of patients beyond age 20 with congenital aortic stenosis will present some degree of calcification in the aortic valve.
    Aortic Stenosis has hemodynamic significance not till 70% of the aortic valve area is reduced. The normal area of the aortic valve in the young adult is between 2.5 and 4 cm². Symptomatology will usually appear when the aortic valve area is below one square cm. and the critical area seems to be approximately 0.5 cm².

PHYSIOPATHOLOGY AND HEMODYNAMICS

    The hemodynamic significance of this disease will depend upon the severity of the aortic stenosis.
    The second factor is the degree of responsiveness of the left ventricle to overcome such narrowing (LVH).
    From the hemodynamical viewpoint two main features should be underlined in relation to the severity of the stenosis.

1. Aortic gradient
2. Cardiac output

    The analysis of the ejection fraction is also important. All these factors are perfectly identified in the Gorling and Gorling formula.
    The more severe the aortic stenosis the higher the aortic valvular gradient. Such gradient is observed during the pullback pressure recording across the aortic valve with a catheter, or recording simultaneous pressure in the ascending aorta and in the left ventricular cavity.
    In any event it is erroneous to parallel the severity of the aortic stenosis with the magnitude of the gradient. It is well known that when congestive failure develops, the gradient can reduce its significance, simulating a moderate and even mild aortic stenosis. This is why the correlation between gradient, heart rate, ejection fraction and cardiac output is important as observed in the Gorling and Gorling formula for the correct evaluation of the aortic valve area.
    The evolution of the symptomatology and the hemodynamic of AS is not only related to the magnitude of the aortic stenosis but to the way the left ventricular wall responds to such physical impediment to the normal blood flow.
    However, many still classify aortic stenosis severity in relation to the valvular gradient, and from this viewpoint, and underlying the previous limitations of this method, the disease can be categorized as follows:

1. Mild aortic stenosis with an aortic valvular gradient below 25mm Hg.
2. Moderate aortic stenosis with a valvular aortic gradient between 25 and 60 mm Hg.
3. Severe with an aortic valve gradient over 65 mm Hg.
4. Critical aortic stenosis with an aortic valvular gradient over 100 mm Hg.

    (Usually the critical aortic stenosis corresponds to the aortic valvular area below 0.5 cm².)
    Aortic stenosis is an evolving disease, tending to produce hemodynamical consequences after the patient reaches age 15 and when the aortic valve is below 1.2 cm².
    This is a disease where typically the deficit is manifested with physical activity. What may be a normal cardiac output with the patient resting may be abnormal if some degree of physical activity developed (difficulty of the left ventricle to increase the cardiac output despite prolongation of the left ventricular ejection fraction).

CLINICAL PICTURE

    Most of the patients do not present symptomatology until after 15 years of life. If the disease is severe or critical since birth, patients may present with congestive heart failure during the first two years of age and the risk of sudden death, and pulmonary edema is high. It is frequently seen that if the patient overcomes age two, the symptomatology many times improves, probably in relation with the development of left ventricular hypertrophy, but signs of congestive failure usually reappear after age 15.
    The most frequent symptoms are related to physical activity and they are as follows: general fatigue with mild or moderate aortic stenosis in relation to physical exertion and probably due to a low and fixed cardiac output at the time of exercise.
    Signs of congestive heart failure in severe or critical aortic stenosis as a sign of left ventricular claudication is usually a terminal symptom.
    As previously observed, left ventricular failure is most frequent below two years of age and when the patient is older than 15.
    Angina pectoris is a sign of critical aortic stenosis and is more frequently observed with patients older than 20 years of age.
    Syncope is another symptom of critical stenosis. It is secondary to sudden drop of the cardiac output during physical exertion but it may be secondary to ventricular fibrillation or other dangerous arrhythmia.
    Sudden death may occur at any age and usually is present in severe or critical aortic stenosis.     Growth and development are normal, and this malformation does not generate cyanosis.

PHYSICAL FINDINGS

    In general, aortic stenosis will be seen in most countries and is four to five times more frequent in males than females. As previously noted, growth and development in these patients are normal and the degree of symptomatology is moderate if the stenosis is mild or moderate, being much more significant when the AS reaches critical levels.
    The most typical findings are:
    Sustained apical impulse.
    Systolic thrill palpable in the second right intercostal space and over the carotid artery areas if the stenosis is moderate, severe or critical. The absence of these signs usually indicates that the obstruction is either mild or extreme.
    Systolic ejection murmur in the second right intercostal space radiated to the carotid area is typical. Many times the murmur is louder in the apex (Gallavardin phenomenon).
    First sound is diminished in intensity or normal. The second sound is normal, or may present splitting and in case of critical stenosis, paradoxical splitting is present.
    A third heart sound may be present in the low left sternal border and apical area.
    The analysis of the aortic stenosis by auscultation and phonocardiography can provide many clues in the evaluation in the severity of the disease as follows:
    The systolic ejective murmur usually has a free space between the initiation of the murmur and the first sound. The later the peak of the murmur, which at times may involve the pulmonic component of the second sound (paradoxical splitting of the second sound), the more severe the stenosis. Phonocardiography is essential for the analysis of the paradoxical splitting and to determine the location of the maximal intensity of the ejection murmur. Systolic click may be noted by phonocardiography in many patients. From the practical viewpoint, if the second sound is normal, only a mild or moderate aortic stenosis can be implied. On the other hand, paradoxical splitting of the second sound indicates a severe or critical aortic stenosis. Atrial gallop (S4) can be also seen in severe stenosis.
    The AS pulse is described as parvus and tardus. The pulse volumeis diminished, and the carotid pulse typically anacrotic.

ELECTROCARDIOGRAM

    If the stenosis is severe enough, the electrocardiogram will depict changes of left ventricular hypertrophy with features of left ventricular pressure overload (systolic overload).

The main criteria are as follows:

R1 + SIII equal or greater than 23 mm. (Lewis criterion)

R in avL higher than 11 mm.

R in avF higher than 18 mm.

S in lead V₁ higher than 23 mm.

R in V₅ or V₆ higher than 35 mm.

Left axis deviation over the frontal plane and counter-clockwise rotation over the. horizontal plane.

Lengthening of the ventricular activation.

T wave inversion in leads V₄, V₅, V₆ avL and lead I.

ST segment depression in the same leads.

Upright T wave in avR as expression of left ventricular systolic overload.

ROENTGENOGRAM

    Usually the left ventricular hypertrophy, even in severe aortic stenosis, is many times insignificant from the radiological viewpoint. Only in the terminal stages when congestive failure develops and dilatation of the previously reported concentric hypertrophy occurs,the left ventricular shadow will enlarge. Post-stenotic dilatation of the ascending aorta can be seen. In many young children, this aortic dilatation is one of the few radiological findings and in general, its magnitude increases with age. Calcification of the aortic valve is a sign worth looking for, since it is unusual in early age in AS of different etiology (RHD).
    The analysis of the pulmonic arch is important since the combination of aortic and pulmonic stenosis is not uncommon and it should be excluded before any surgery is considered.

ECHOCARDIOGRAM IN AORTIC STENOSIS

    Bicuspid aortic valve: The sonographic criterion is still relatively new and must await further confirmation.
    Evaluation of the degree of stenosis: The echocardiog ram is of poor reliability using the standard M-Mode. Somewhat better information is claimed using real-time cross sectional echocardiography. Aortic valve orifice size can be affected by cardia output, been decreased in patients with low cardiac output. Pulmonary hypertension, however, can be recognized by the characteristic pulmonary valve motion.
    Cardiac ultrasound procedures, however, proved excellent for evaluation of ventricular function, considering that it is a non-invasive procedure. However, it should be remembered that in adult patients if coronary artery disease is present, cardiac ultrasound may tend to overestimate the ejection fraction. The secondary thickening of the ventricular wall is easily assessed as is the circumferential fiber shortening and ejection fraction with the limitations just mentioned. Real time echocardiography should be useful in the evaluation of this pathology.
    Bicuspid aortic valve produces marked eccentricity of the aortic valve cusp echoes in diastole. In a large number of patients with bicuspid valve multilayed echoes can be demonstrated echocardiographically during diastole. However, although eccentricity of the diastolic aortic valve echoes appears specific for a bicuspid aortic valve only 75% of this sonographic diagnosis finally correlates with real biscuspid valve. The remaining 25% is artifactual asymetry produced mainly by wrong transducer angulation.

CARDIAC CATHETERIZATION AND ANGIOCARDIOGRAPHY

    A quite accurate evaluation of the significance of the aortic stenosis can be reached with a careful clinical observation, the stethoscope and non-invasive procedures. In any event, prior to any surgical consideration, a careful hemodynamic analysis with left cardiac catheterization, at least, and left ventricular angiography must be attempted. The selective coronary angiography is essential in order to rule out any simultaneous coronary artery disease which, incase of being present may need correction during the same surgery.
    The search for other congenital diseases should be never underemphasized since approximately 25% of these patients may present some other heart malformation.
    The more essential left cardiac catheterization data is:

1. The determination of the aortic valve systolic gradient during the pullback pressure recording across the aortic valve.
   
2. The left ventricular systolic pressure and left ventricular end diastolic pressure. Afterload however does not appear to be a major factor in determining the severity or in separating different categories of patients.
   
3. Right cardiac catheterization is advisable in order to rule out pulmonic stenosis and to obtain blood samples from the main pulmonary artery in order to determine cardiac output which is essential for the final calculation of the aortic valve using the Gorling and Gorling formula.
   

    In many cases, the passing of the catheter toward the left ventricle is extremely difficult due to the small area of the valve and transeptal catheterization may be attempted.
    Biplane left ventricular angiogram is important as injecting the ascending aorta for evaluation of post stenotic dilatation.
    Angiography will demonstrate the typical dye ejection jet through the stenotic valve, make graphic left ventricular contractility and rule out any degree of signficant mitral insufficiency present. Left ventricle angiogram is still the most accurate way to evaluate ventricular function in these patients.
    The analysis of the pressure contour (left ventricular pressure, aortic or carotid pressure) will show typical features in the case of severe or critical AS. Prominent a wave will be seen in the aortic valve as prolongation of the ejection fraction and notching of the ascending limb. The same findings can be seen in the carotid pulse. The pullback pressure recording across the aortic valve will demonstrate the systolic gradient between both cavities (left ventricle and aorta).
    The Gorling and Gorling formula can be used as explained elsewhere, for the calculation of valve area. However in very low cardiac output situations, the hydraulic constant of such equation may not be applicable.
    The gradient may be difficult to assess in patients with coarctation of the aorta and arterial hypertension.
    Cardiac ultrasound procedures proved excellent for evaluation of ventricular function, but if coronary artery disease is present the echocardiogram may tend to overestimate the ejection fraction.

MEDICAL AND SURGICAL TREATMENT

    In children below two years of age if severe aortic stenosis is present, the more critical problem is the control of recurrent congestive failure.
    Subacute bacterial endocarditis is frequent, and its clinical course does not necessarily differ from other circumstances. Antibiotics should be given routinely to these patients to prevent SBE and development of aortic insufficiency.
    If congestive failure develops in young children below two years of age, surgery as an emergency should be considered. The operation is also indicated in infants, children or adults with angina pectoris, left ventricular failure and syncope.
    Regardless of the symptomatology, however, most of the congenital stenosis with a systolic gradient higher than 60 mm. of mercury probably deserves surgical correction. The operation is usually done with cardiopulmonary bypass opening the aortic root previous closed and clamping of the vessel. In the case of pure aortic stenosis commisurotomy can be attempted and usually incompetence does not result if it is done correctly.
    If calcification is significant in adults and commisurotomy produces a large aortic insufficiency, resection of the aortic valve is many times necessary with implanting of a prosthetic device. Continuing improvement in artifical valve design and in the preparation of homograft valves make actually the prognosis much better after surgery and earlier operation is possible.
    The results are, in general, quite good and the hospital mortality rates are low with satisfactory early results.
    Endocardial fibroelastosis in infants constitutes in any event an extra operative risk.

CONGENITAL AORTIC REGURGITATION

1. Unicommisural aortic valve
2. Bicuspid aortic valve
3. Tricuspid aortic valve
4. Quadricuspid valve common in troncus arteriosus.
5. Aortic Regurgitation associated to valvular or supravalvular aortic stenosis
6. Supracristal ventricular septum defect.

Electrocardiogram of a 27 year-old male with severe congenital Aortic Stenosis. The aortic valve gradient was 85 mm Hg.