Clinical features of severe aortic stenosis

Clinical features of severe aortic stenosis

Symptoms of severe aortic stenosis (AS)

Angina, syncope and features of heart failure are the important symptoms of AS which correlate with survival. The median survival with these symptoms are five, three and two years respectively. Angina occurs in AS because of a demand supply mismatch in a hypertrophied left ventricle. Syncope is related to exercise and is due to a relatively fixed cardiac output in the face of systemic vasodilation which occurs with exercise. Since the cardiac output can hardly increase with exercise in severe AS, cerebral hypoperfusion and syncope results.

In degenerative calcific aortic stenosis which is seen mostly in the elderly, average survival after the onset of symptoms, is 2-3 years [1]. Patients with syncope, angina, and dyspnoea need prompt aortic valve replacement. Aortic stenosis is the most common valvular lesion in Europe and North America [1].

Pulse in AS

The characteristic pulse in severe AS is slow rising low volume pulse known as pulsus parvus et tardus. A bisferiens pulse is noted in a combination of aortic stenosis and aortic regurgitation. Bisferiens pulse has two peaks in systole and is more likely to occur in free aortic regurgitation or dominant aortic regurgitation rather than in dominant aortic stenosis.

Pulsus alternans has been described in acquired aortic stenosis [2]. But the finding was mostly in left ventricular pressure tracings and the amplitude of variation was much lesser in arterial pressure tracings. It was not seen in congenital aortic stenosis of similar severity in that study.

Blood pressure in severe aortic stenosis

The systolic pressure is low and the pulse pressure is narrow in severe aortic stenosis. But hypertension can occur in degenerative aortic stenosis, particularly in the elderly. In one study, 32% of the 193 patients with symptomatic aortic stenosis had history of hypertension while the remaining 131 patients were normotensive [3].

Apex beat in aortic stenosis

The apex is formed by the left ventricle in aortic stenosis and it is a heaving (sustained and forceful) apex in severe aortic stenosis.

Heart sounds in aortic stenosis

In severe AS, the aortic component of second heart sound is soft and delayed, sometimes even a paradoxical split may occur. Fourth heart sound may be audible due to the forceful atrial contraction needed to improve the filling of a hypertrophied left ventricle. Third heart sound can be heard in left ventricular failure.

Thrill and murmur in aortic stenosis

A systolic thrill is felt in severe AS in the aortic area and over the carotids. A systolic thrill can also occur in lower degrees of aortic stenosis if there is associated aortic regurgitation. The ejection systolic murmur is harsh, loud, long, late peaking and best heard in aortic area and conducted to the carotids in severe AS. The murmur may become less audible if the left ventricle fails and hence severe AS is an important differential diagnosis of dilated cardiomyopathy. When the left ventricular function improves with treatment or inotropic support, the murmur becomes more prominent in severe AS with heart failure. In aortic stenosis of the elderly, the murmur of aortic stenosis is harsh in the aortic area and more musical in the mitral area resembling associated mitral regurgitation. This phenomenon is known as Gallavardin dissociation. It was described by Gallavardin in 1925 [4]. The harsh murmur in the aortic area is due to turbulent flow across the stenotic aortic valve and the musical murmur in the mitral area is supposed to be due to the vibration of the left ventricular outflow tract. Gallavardin postulated that the high pitched musical components of the murmur of aortic stenosis were preferentially transmitted to the apex through solid tissues while lower pitched components were transmitted to the neck vessels through the blood flow. Giles TD et al proposed that the high pitched musical murmur could be due to associated papillary muscle dysfunction [4].

References

1. Ramaraj R, Sorrell VL. Degenerative aortic stenosis. BMJ. 2008 Mar 8;336(7643):550-5.
2. Cooper T, Braunwald E, Morrow AG. Pulsus alternans in aortic stenosis; hemodynamic observations in 50 patients studied by left heart catheterization. Circulation. 1958 Jul;18(1):64-70.
3. Antonini-Canterin F, Huang G, Cervesato E, Faggiano P, Pavan D, Piazza R, Nicolosi GL. Symptomatic aortic stenosis: does systemic hypertension play an additional role? Hypertension. 2003 Jun;41(6):1268-72.
4. Giles TD, Martinez EC, Burch GE. Gallavardin phenomenon in aortic stenosis. A possible mechanism. Arch Intern Med. 1974 Oct;134(4):747-9.