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What is a Diastole?

MVSAT 2024

A diastole or diastolic function of the heart is the process where the heart muscles go through relaxation which is followed by the filling of blood in the heart's chambers. This as a result decreases the blood pressure of an individual. Thus, diastole heart function is a phase in the cardiac cycle of a person which is responsible for ventricular relaxation along with the active and passive filling of blood in the heart chambers before pumping them out throughout the body.

This is a very important topic for understanding the cardiac cycle of humans and how an abnormal diastolic function can result in several heart diseases. 

This article provides information on ventricular diastole and left ventricular diastolic dysfunction definition. Students can also refer to this article to understand diastolic dysfunction meaning. 

Definition of Diastole and Systole

Before understanding the cardiac cycle and knowing the abnormalities of heart functioning, it is important to get a clear understanding of the diastole and systole.

Ventricular diastole and systole form a major part of the cardiac cycle. These can be defined as the two periods in a cardiac cycle which occurs in the form of heartbeats. They pump the blood through the blood vessels which is carried to each and every part of the body. 

Diastole is the relaxation of the ventricles and pumping of blood into the heart chambers while systole can be defined as the contraction of heart muscles to pump out blood in the entire body.

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Ventricular Diastolic Dysfunction

The trouble in relaxation of heart muscles and reduction in the pumping of blood into the ventricles of the heart is known as ventricular diastolic dysfunction. 

Left ventricular diastolic dysfunction (DD) is characterized as the ventricle's failure to fill to a normal end-diastolic volume, both during exercise and at rest, while left atrial pressure does not surpass 12 mm Hg.

The occurrence of mild diastolic dysfunction starts with slow heartbeats due to the limited amount of blood flow in the ventricles required for the next heartbeat

A normal left ventricular diastole requires proper relaxation, contraction and ejaculation of blood throughout the body for normal functioning of the heart. 

The two common main reasons for left ventricular diastole dysfunction are:

  1. Due to an Overworked Heart Muscle: This is caused by the high amount of physical activity which as a result thickens the muscles of the heart creating less space inside the heart ventricles for filling in blood.

  2. Clogged Arteries: Muscle bulking and stiffening of heart muscles can be genetic but the most common factors for these has always been a high level of cholesterol and blood pressure. Clogging of heart arteries results in narrowed heart valves which block several proteins, irons and other substances to filtrate out of the arteries making the heart stiffer.

Causes and Effects of Diastolic Heart Failure

Several factors contribute to abnormal functioning of the heart. Some of the main factors include ageing, aortic stenosis, pericardial diseases and hypertrophic cardiomyopathy. 

Hypertrophic cardiomyopathy is the abnormal thickening of the left ventricular wall while aortic stenosis can be defined as the narrowing of the aortic valve opening.

These abnormalities lead to the accumulation of fluids in the pericardial space causing a sudden heart failure.

Other factors for diastolic dysfunction include diabetes, high blood pressure, obesity and coronary heart diseases. 

Symptoms of Diastolic Heart Failure

Although people show no diastolic dysfunction symptoms, many may experience issues with breathing difficulty, fatigue and irregular heartbeat. They also face difficulty in doing physical activities and have a lack of appetite. Many severe symptoms include abdominal swelling, rapid weight gain and swelling of the ankle and legs (edema). 

Many people also face severe chest pain and foamy, pink mucous after coughing. Therefore it is important to do a regular checkup of your heart and maintain a low cholesterol level for better functioning of the heart.

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FAQs on Diastole

1. Can Diastolic Dysfunction Lead to Serious Heart Problems?

Ans. Yes, diastolic dysfunction is a serious heart problem that causes abnormal functioning of the heart. During this, our heart is unable to relax and thus the ventricles are able to pump in a very little amount of blood and leads to a low heartbeat rate. 

2. What is a Cardiac Cycle?

Ans. A cardiac cycle can be defined as a process that is responsible for the circulation of blood in our body. It is an important activity for the functioning of the human heart. It is regulated by the sinoatrial node and atrioventricular nodes, also togetherly known as nodal tissues. Our heart takes 72 cardiac cycles per minute i.e., 72 heartbeats per minute. 

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