Pulsus bisferiens, also known as biphasic pulse, is an aortic waveform with two peaks per

cardiac cycle The cardiac cycle is the performance of the human heart from the beginning of one heartbeat to the beginning of the next. It consists of two periods: one during which the heart muscle relaxes and refills with blood, called diastole, following ...

, a small one followed by a strong and broad one. This reference illustrates the normal and abnormal spectral waveform. It is a

sign A sign is an object, quality, event, or entity whose presence or occurrence indicates the probable presence or occurrence of something else. A natural sign bears a causal relation to its object—for instance, thunder is a sign of storm, or me ...

of problems with the aorta, including aortic stenosis and

aortic regurgitation Aortic regurgitation (AR), also known as aortic insufficiency (AI), is the leaking of the aortic valve of the heart that causes blood to flow in the reverse direction during ventricular diastole, from the aorta into the left ventricle. As a conseq ...

, as well as

hypertrophic cardiomyopathy Hypertrophic cardiomyopathy (HCM, or HOCM when obstructive) is a condition in which the heart becomes thickened without an obvious cause. The parts of the heart most commonly affected are the interventricular septum and the ventricles. This r ...

causing subaortic stenosis. __TOC__

Pathogenesis

In hypertrophic cardiomyopathy, there is narrowing of the

left ventricular outflow tract A ventricular outflow tract is a portion of either the left ventricle or right ventricle of the heart through which blood passes in order to enter the great arteries. The right ventricular outflow tract (RVOT) is an infundibular extension of the ...

(LVOT) due to hypertrophy of the

interventricular septum The interventricular septum (IVS, or ventricular septum, or during development septum inferius) is the stout wall separating the ventricles, the lower chambers of the heart, from one another. The ventricular septum is directed obliquely backwar ...

. During systole, the narrowing of the LVOT creates a more negative pressure due to the Venturi effect and sucks in the anterior mitral valve leaflet. This creates a transient occlusion of the LVOT, causing a midsystolic dip in the aortic waveform. Towards the end of systole, the ventricle is able to overcome the obstruction to cause the second rise in the aortic waveform. In severe aortic regurgitation, additional blood reenters the left ventricle during diastole. This added volume of blood must be pumped out during ventricular systole. The rapid flow of blood during systole is thought to draw the walls of the aorta together due to the Venturi effect, temporarily decreasing blood flow during midsystole. A recent paper theorized that an alternative explanation for pulsus bisferiens may be due to a forward moving suction wave occurring during mid-systole.

References

External links

Symptoms and signs: Cardiac {{med-sign-stub