Heart Valves and the Cardiac Cycle

This flashcard set covers the anatomy of heart valves, the phases of the cardiac cycle (systole and diastole), flow dynamics (laminar vs. turbulent), and key valvular pathologies.

Systole

The phase where the ventricles are emptying by contracting the myocardium; it includes isovolumic contraction, rapid ejection, and reduced/slow ejection.

Diastole

The phase where the ventricles are filling; it includes isovolumic relaxation, rapid filling, diastasis, and atrial systole.

Isovolumic relaxation

A phase where volume in both ventricles is equal and unchanged, while the pressure is drastically decreasing and muscle tension is decreasing.

Isovolumic contraction

A phase generally lasting around $0.03\,s$ or $5-6\%$ of the cardiac cycle where volumes are nearly equal in both ventricles, pressure is drastically increasing, and muscle tension is increasing.

Distal

An anatomical direction meaning further away from the start/source/origin.

Proximal

An anatomical direction meaning closer to the start/source/origin.

Medial

An anatomical direction meaning closer to the center/midline.

Lateral

An anatomical direction meaning away from the center/midline.

Rapid ejection

The first phase of mechanical systole which begins when the pressure in the LV has surpassed that of the aorta, causing the aortic valve to open.

Diastasis

A period in diastole where pressures have equalized and volume has increased in the LV, resulting in a slowing or standstill in the movement of blood from the LA to the LV.

Atrial systole

Also known as the "atrial kick," this is the contraction of the LA that forces blood from the LA to the LV.

Laminar Flow

Normal, steady blood flow where the majority of blood travels in one direction at the same velocity without swirling, showing uniform tracings on spectral Doppler.

Turbulent Flow

Flow characterized by increased pressures and velocities, swirling of blood in numerous directions, and an increased mosaic pattern on color flow Doppler.

Valvular stenosis

The narrowing or obstruction of a valve area that restricts flow, increases the pressure gradient across the valve, and causes turbulent flow in the downstream chamber.

Valvular regurgitation

The failure of complete coaptation of valve leaflets or cusps, resulting in retrograde, turbulent flow into the upstream chamber.

Atrioventricular (AV) valves

Valves located between the atrium and ventricle (Tricuspid and Mitral) that open in diastole when atrial pressure is higher than ventricular pressure.

Semilunar Valves

The aortic and pulmonic valves, which are made of 3 crescent moon-shaped cusps and are open during systole to allow blood ejection into the arteries.

Chordae tendineae

Tendinous cords that tighten during ventricular contraction to prevent the valve leaflets from inverting or prolapsing.

Tricuspid Valve

The valve between the RA and RV consisting of an annulus, chordae tendineae, 3 papillary muscles, and 3 leaflets: Anterior, Septal (medial), and Posterior.

Mitral Valve (bicuspid valve)

The valve between the LA and LV composed of 2 leaflets (Anterior and Posterior) and 2 commissures (Lateral and Medial).

Nodules of Arantius

Small nodules found at the tip of each semilunar valve cusp (both aortic and pulmonic).

Sinus of Valsalva

The pouch-like dilation located behind each cusp of the aortic valve.

Bicuspid aortic valve

The most common congenital heart defect in the adult population.

ECG Square Value

On an electrocardiogram, 1 square represents $0.04\,\text{sec}/0.1\,\text{mV}$.