thickened due to the resultant anoxia and pulmonary hypertension develops →this leads to right venlricular hypertrophy and finally failure.

the finer vessels become thickened due to the resultant anoxia and pulmonary hypertension develops →this leads to right venlricular hypertrophy and finally failure. As a resulf of pulmonary congestion, pulmonary capillary BP rises → pulmonary edema develops. Recall, normally, lung fields are dry primarily because of low (about 9 mm Hg) capillary BP in the pulmonary circulation. But in mitral stenosis this may become something like 20 or 25 mm Hg. Characteristic clinical finding of mitral sfenosis is mid diastolic murmur and where the heart is beating regularly with a sinus rhythm ( = pace maker remains the SAN), there is usually a presystolic accentuation. Atrial fibrillation often develops in cases of mitral stenosis and with the onset of atrial fibrillation, the presystolic accentuation disappears. Explanation of the murmur. Recall, in most situations, normally, flow of the blood is streamllie Streamline flows are silent but turbulent flows are noisy. Streamline flows can become turbulent (and, therefore, noisy), under some circumstances, like when the Reynold's number exceed 1000 (chap 7 sec V). For example, when the velocity of blood rises or the lumen of the vascular tube is very wide, the stream line flow becomes turbulent (and noisy) because it exceeds the critical Reynold's number of 1000. " British physiologist and clinician (a renowned cardiologist), Lewis made lasting contributions in many fields, like ECG, pain producing substance- substance P histamine, circus movement and was also guru of Pickering (the great exponent of hypertension). Sir Thomas worked mostly in the pre 2nd world war time. However, if the flowing blood meets an obstacle, the flowing blood rebounds the particles of blood collide with one another turbulence is produced. This type of turbulence will be produced, even when the Reynold's number is much below 1000. In mitral stenosis, there is narrowing of the mitral opening (from a normal value of 4 to 6 sq cm, the orifice may become now well below 2 sq. cm). This produces an obstruction to the flow murmur develops with a Reynold's number value well below 1000. Nevertheless, if the velocity be increased (eg. by exercising the patient) the murmur becomes louder. The presystolic accentuation is due to the last rapid filling phase which in turn is due to atrial contraction, causing increase in the velocity. In atrial fibrillation, where there is no atrial contraction, there is, therefore, no presystolic accentuation. II. Mitral incompetence Vast majority of mitral incompetence cases are chronic cases and most ol them are of rheumatic fever origin. Mitral valve prolapse, however, is another important cause, particularly in the west In mitral incompetence, the mitral valves cannot close completely during ventricular systole as a result, some blood from the left ventricle regurgitates into the left atrium during ventricular systole (mitral regurgitation) a the regurgitated blood may also enter the pulmonary veins. Characteristic finding in mitral incompetence is a systolic murmur (= murmur during ventricular systole). Recall, part of the 1st heart sound is due to turbulence created by rebounce of blood from the undersurface of the mitral valve during ventricular contraction. To this, another kind of turbulence is created due to leakage of blood into the atrium. Left atrium contains extra blood due to regurgitation. This extra blood can produce 3rd heart sound (protodiastohc gallop ) during 1st rapid filling phase. III. Aortic incompetence (regurgitation) Great majorities of aortic incompetence cases are chronic. Rheumatic fever is a very important cause, syphilis is another. Rheumatic fever can cause scarring of the aortic valve a condition is created when these valves cannot close properly therefore, blood from the aorta regurgitates into the left ventricle during ventricular diastole ventricle receives extra blood in its diastohc period (volume overload or preload, see chap 2 sec V) operation of Frank Starling's law rise in stroke volume sharp rise in systolic BP (SBP). Further, regurgitation causes too quick and too extensive draining of blood from the aorta reduction of diastohc BP (DBP), further, duration of diastole is also short. Major findings of aortic incompetence, are therefore, (i) a water hammer pulse, (ii) high SBP but low DBP (eg. 160/ 30 mm Hg) both the features are due to reasons stated above (see also 'water hammer pulse' in 'pulse' chap 9 sec V); and (mi) a diastohc murmur (which is due to turbulence of blood in the ascending arota and left ventricular cavity) heard in the clinical aortic area. As coronary arteries are filled mostly in the diastole, and as the DBP is very low in such cases, in aortic incompetence cases, coronary supply is often geopardised. HEART FAILURE Heart failure may be viewed as a condition, where there is insufficient contractility (inotropic state) of the heart which results in such a reduction of cardiac output despite adequate venous filling that it leads to insufficient perfusion of the tissues. In the beginning, there operate the compensatory mechanisms and in well compensated cases ('mild heart failure') patient may remain reasonably symptom free at rest. In advanced or severe heart failure, despite the operation of compensatory mechanisms, the patient worsens. [This definition of heart failure covers only the 'classical or systolic heart failure'. Other types, however, have been ignored to keep the discussion simple. ] The signs and symptoms of heart failure are to a large extent, due to the compensatory mechanisms. In dealing with the heart failure, traditionally, two terms are used : (1) Forward failure (introduced