Aortic incompetence may result from dilatation of the aortic ring.Damage of the value cusp or loss or support of the cups.
. Acute onset disease (20%)
. Chronic onset disease (80%)
Here elastic coat of aorta is replaced by fibrous coat and there is intimal proliferation. The fibrous coat yields to dilatation, resulting in dilatation of aortic ring.
Due to rapid run off of blood from aorta to the LV, left ventricular blood volume increases which left ventricular muscle resists and interpericardial pressure rises.To facilitate left ventricular filling from LA in diastole, the filling pressure rises which results in elevation of left atrial and pulmonary capillary pressure. So, there is abrupt rise in after load which may lead to LVF. Due to non-complaint pericardium left ventricular filling is interfered with, which may lead to increase in right atrial and RV pressure. Due to limited forward stroke volume there is peripheral vasoconstriction and moderate fall of aortic diastolic pressure. So the aortic diastolic murmur is short and less pronounced in early stage and peripheral signs of chronic lesion are absent. Due to markedly reduced coronary blood flow from high filling pressure of left ventricle and low aortic diastolic pressure there is myocardial ischaemia, infarction arrhythmias resulting in sudden death.
The regurgitant column of blood from aorta and the usual left ventricular blood flow from left atrium will cause increased blood volume of the left ventricle in diastole. According Frank Starling’s law left ventricular force of contraction and stroke volume both are increased. As, end diastolic volume will progressively rise. This will lead to sarcomere replication in series ultimately resulting in hypertrophy of left ventricle. Left ventricle, therefore, shows both hypertrophy and dilatation (eccentric hypertrophy). In course of time gradually left ventricle fails. As total stroke volume is increased pulse pressure also increases because.
This wide pulse pressure will lead to development of classical peripheral signs of Aortic incompetence which are however absent in Acute lesion.
CLINICAL FEATURES (CHRONIC LESION)
Average age 30 years and males predominate (3:2).
The disease may also remain asymptomatic
The head and body of the patient may be seen shaking with each heart beat (de Musset’s sign). Carotid dance (Corrignan’s sign), locomotor brachialis or serpent brachialis and peripheral vascular dance are present. Capillary pulsation of Quincke may be seen on the nail beds, everted lips, scratch mark on the forehead and by ophthalmoscopic examinations. Uvular pulsation (Muller’s sign) may also be present. Pulse is characteristically water hammer or collapsing in type. This is also called Corrigan’s pulse. It is a high volume ill-sustained pulse with abrupt rise and abrupt fall. When there is aortic stenosis in addition, pulsus bisferiens is found. This type of pulse may sometimes also be present even in absence of aortic stenosis. BP shows high systolic pressure (due to increased stroke volume) and a low diastolic pressure (due to carotid sinus reflex resulting in peripheral vasodilatation and also due to reflux of blood from the aorta.
So, the pulse pressure is very high (more than 60 mm of Hg). High pulse pressure is the cause of all the above peripheral vascular signs. The wide pulse pressure in Aortic incompetence in turn may stimulate Baroreceptor reflex causing further widening of pulse pressure. Sometimes BP in lower limbs may be higher than that of the upper limbs (Hill’s sign) to maintain adequate cerebral circulation. The venous pulse may rarely show a Bernheim ‘a’ wave.
Apical impulse may be seen to be displaced downwards and to the left. It is forceful but ill-sustained (hyperkinetic or hyperdynamic) in type.
Apical impulse is forceful and hyperkinetic, rarely a palpable ‘a’ wave is felt. A diastolic thrill may rarely be palpable along the left sternal border. Sometimes a systolic thrill may be felt over the suprasternal notch and upwards along the carotids. This systolic thrill is due to increased rush of blood through aortic orifice and does not necessarily mean aortic stenosis.
A, may be normal or may be feeble. Rarely it may be accentuated. A systolic click over aortic area may be heard which is due to dilatation of aorta. S3 and S4 may rarely be audible. The characteristic and diagnostic finding is high pitched blowing early diastolic murmur over the aortic area immediately following A, which is well conducted along the left border of the sternum to the apex beat. In rheumatic cases the murmur is best heard over left 3rd space sometimes over 4th space close to sternum, called neoaortic area or Erb’s point and in syphilitic cases it is best audible over the aortic area. The murmur may be loudest at the apex or at the left axilla (Cole-Cecil murmur). Due to infective endocarditis perforating the aortic valve or in cases of ruptured sinus of valsalva and sometimes in syphilitic cases this murmur may have a musical quality (Seagull murmur or Cooing Dove murmur). The murmur of Aortic Incompetence is best heard by pressing the diaphragm of chest piece over the aortic area after holding the breath in full expiration with the patient erect and leaning forward. Sometimes a functional mid- diastolic and pre-systolic murmur may be heard over mitral area, called Austin-Flint’s murmur. This is due to relative mitral stenosis produced by the apposed aortic cusp of the mitral valve towards its opposite partner by the aortic regurgitant jet or due to vibration of Aortic cusp of mitral valve by regurgitant jet. Some also think that it may be due to relative mitral stenosis produced by hugely dilated left ventricle in absence of mitral ring dilatation. When left ventricle dilates a pansystolic murmur may be heard over mitral area replacing this murmur.
Peripheral vascular signs:
On light application of the chest piece of the stethoscope over the medium-sized vessels, e.g., brachial or femoral, a pistol shot sound is heard (Traube’s sign). Sometimes double sounds may also be heard (Traube’s double sound). On applying pressure on the proximal segment of the vessel a systolic murmur and on the distal segment a diastolic murmur may be heard. The latter is called Duroziez’s murmur. All these constitute Duroziez’s sign. Duroziez’s sign is particularly important because it is present in moderate to severe aortic incompetence even in absence of aortic diastolic murmur.
Sudden dyspnoea occurs in 50% of cases due to left ventricular failure resulting in pulmonary oedema. There may be systemic embolic manifestations and fever may be present. When right coronary artery becomes occluded features of Inferior wall infarction may be present but when left coronary artery is occluded, the patient invariably dies. Chest pain, cough, frothy sputum, haemoptysis, features of shock mental confusion, etc. may also be present.
Features of peripheral circulatory failure, sweating, tachycardia, signs of shock, pulmonary oedema are seen. There is no hypertrophy and dilatation of left ventricle. The aortic diastolic murmur is short and inaudible but classic peripheral vascular signs are always absent. If the patient survives, after one year features of chronic Aortic regurgitation will develop.
Severe pulmonary hypertension with Graham-Steel murmur: Evidences of pulmonary hypertension are present, peripheral signs of aortic incompetence are absent, X-ray shows dilatation of the pulmonary trunk, echo shows fluttering of the tricuspid valve during diastole.
Other conditions with early diastolic murmurs such as PDA, coronary arteriovenous fistula, ruptured sinus of valsalva are also to be differentiated. They all are causes of continuous murmur. Cardiac catheterization and aortography may sometimes be helpful.
Course and Prognosis:
Mild degree of aortic incompetence may be compatible with a normal life span. In severe cases, usually disability sets in, in fourth or fifth decade of life. In presence of recurrent dyspnoea and cardiomegaly life expectancy is not more than 2-3 years.
Mild to moderate cases may require palliative treatment with prophylactic antibiotics and diuretics. In syphilitic cases appropriate antibiotics should be given. Afterload reducing agents like Hydralazine or ACE inhibitors are useful in chronic cases which may reduce regurgitant jet, end systolic and end diastolic volume of left ventricle and increase the ejection fraction. Vasodilator therapy is particularly useful in chronic severe AR for haemodynamic improvement as a short-term therapy or as long-term therapy if valve replacement is not possible or if LV dysfunction develops after valve replacement and also in asymptomatic patients. In acute lesions pre load and after load reduction is life saving which may be achieved by using Nitroprusside. In severe cases aortic valve replacement surgery should be done. In acute aortic Regurgitation which usually develops after infective endocarditis, appropriate antibiotics and vasodilators should be used first followed by surgery. In many centres now-a-days valve repair is being done by new technique in chronic cases of AR.
When valve replacement is considered it should be well ahead before symptoms of cardiac failure set in. Once failure develops full recovery of myocardium is not expected even after valve replacement. In children and young adults tissue valves are not preferred as there is chance of rapid calcification and degenerative changes. In aged individuals tissue valves are better as use of anticoagulants can be avoided.
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