What Is Ventricular Diastole?

After ventricular ejection is completed, the diastolic pressure begins to decrease rapidly. When the arterial pressure drops below the arterial pressure, the arterial valve closes. Atrioventricular valve is still closed. At this time, the ventricular volume does not change, and the pressure gradually decreases. It is called isovolumic diastole, about 0.07 seconds.

After ventricular ejection is completed, the diastolic pressure begins to decrease rapidly. When the arterial pressure drops below the arterial pressure, the arterial valve closes. Atrioventricular valve is still closed. At this time, the ventricular volume does not change, and the pressure gradually decreases. It is called isovolumic diastole, about 0.07 seconds.

Chinese name

Ventricular diastole

Foreign name

ventricular diastole

Department

Cardiology

Ventricular Diastole I. Overview

When the intra-ventricular pressure is lower than the intra-atrial pressure, the atrioventricular valve opens, blood flows from the atrium to the ventricle, and the ventricle begins to fill. The filling period is about 0.43 seconds. Ventricular blood filling in the first 0.33 seconds of this period mainly depends on the "pumping" effect of ventricular diastole, and the inflow of blood accounts for 70% of the total.

Therefore, the pumping function of the heart is mainly accomplished by ventricular diastolic activity. The atrial systole is both the beginning of the cardiac cycle and the last phase of the end-diastolic phase. The blood volume squeezed into the ventricle during atrial systole accounts for 30% of the total ventricular blood volume.

Ventricular diastole

Because diastole is an active energy-consuming process, some scholars consider that diastole is part of the systole in a strict sense, but from the clinical point of view, diastole needs to distinguish between four phases: isovolumic relaxation, rapid early filling, slow ventricle Filling (late diastole), atrial filling.

Ventricular Diastole III. Determinants

Diastolic function is affected by several factors and myocardial retardation, ventricular filling, and passive elasticity of the ventricle, but one of the main determinants is heart rate. Increasing the ventricular rate shortens the diastolic filling time interval disproportionately. This shortening only compensates for increased diastolic rate and enhanced diastolic attraction. Therefore, impaired diastolic function can be exacerbated by tachycardia, and simply reducing the heart rate and extending the diastolic period can improve the prognosis.

In the normal left ventricle, the end-systolic volume is less than its elastic balance force, so the elastic return rate is generated, and the change of the elastic return rate is inversely proportional to the end-systolic volume. The elastic recovery rate causes the diastolic attraction to draw blood into the ventricle under low pressure, and may cause negative pressure in early diastole. This filling mechanism is important during exercise, so that the normal ventricle can reduce the minimum diastolic pressure, and even if the cardiac output is increased by 3 to 5 times, the end diastolic pressure can be maintained constant. Loss of elastic recovery rate and reduction of early diastolic filling during acute ischemia are accompanied by an increase in left atrial pressure and ventricular rate.

Another important determinant of diastolic function is the atrioventricular pressure step, which depends on atrial pressure, diastolic rate, viscous force in the myocardium, and ventricular filling rate. Increasing the sluggish rate can keep the left atrial pressure at normal level. Although the ventricular output is increased, the decrease in ventricular filling rate can be compensated by the increased left atrial pressure.

Ventricular diastole IV, abnormal diastolic function

Diastolic dysfunction: From a clinical point of view, diastolic dysfunction can be called diastolic dysfunction according to its severity; diastolic dysfunction and diastolic heart failure. The diastolic function is characterized by an abnormal filling index, which is usually determined by echocardiography. It has a reduced early filling rate or a prolonged isovolumic diastolic period without clinical symptoms. In this case, the ventricle can compensate for diastolic dysfunction and keep the left ventricle at a normal level.

Diastolic dysfunction is characterized by increased diastolic filling and may be related to dyspnea. This symptom can occur during activity ("potential" diastolic dysfunction), or "resting" diastolic dysfunction can occur at rest. Many patients with moderate to severe left ventricular hypertrophy can develop diastolic dysfunction.

Diastolic heart failure has the clinical symptoms of heart failure, such as paroxysmal nocturnal dyspnea, sitting breathing and edema. The clinical difference between systolic dysfunction and diastolic dysfunction is important because the prognosis and treatment interventions for these two types of heart failure are different.