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 heart, 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, fo ...

, 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 The aorta ( ; : aortas or aortae) is the main and largest artery in the human body, originating from the Ventricle (heart), left ventricle of the heart, branching upwards immediately after, and extending down to the abdomen, where it splits at ...

, including

aortic stenosis Aortic stenosis (AS or AoS) is the narrowing of the exit of the left ventricle of the heart (where the aorta begins), such that problems result. It may occur at the aortic valve as well as above and below this level. It typically gets worse o ...

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 conse ...

, as well as

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

causing subaortic stenosis. __TOC__

Pathogenesis

In hypertrophic cardiomyopathy, there is narrowing of the left ventricular outflow tract (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 ventricle (heart), ventricles, the lower chambers of the heart, from one another. The interventricular septum is di ...

. During systole, the narrowing of the LVOT creates a more negative pressure due to the

Venturi effect The Venturi effect is the reduction in fluid pressure that results when a moving fluid speeds up as it flows from one section of a pipe to a smaller section. The Venturi effect is named after its discoverer, the Italian physicist Giovanni Ba ...

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

{{Cardiovascular system symptoms and signs Symptoms and signs: Cardiac