Your heart may not function normally if the heart valves are not working properly, as this can interfere with blood flow in the heart. The main purpose of the heart is to pump blood through the body; It does this in a repetitive sequence called the cardiac cycle. The cardiac cycle is the coordination of filling and emptying the blood heart by electrical signals that cause the contraction and relaxation of the heart muscles. The human heart beats more than 100,000 times a day. In each cardiac cycle, the heart contracts (systole), extracts blood and pumps it through the body; This is followed by a relaxation phase (diastole) in which the heart fills with blood, as shown in Figure 1. The atria contract at the same time, forcing blood through the atrioventricular valves into the ventricles. Closing the atrioventricular valves produces a monosyllabic “Lup” sound. After a short time, the ventricles contract and at the same time force blood through the valves of the crescent in the aorta and the artery that carries blood to the lungs (via the pulmonary artery). Closing the crescent valves produces a monosyllabic “dup” sound. Problems with your cardiovascular system include: The right side of the heart receives oxygen-depleted blood because most of it has been consumed by the brain and body.
It pumps this into your lungs, where it absorbs a new supply of oxygen. The blood then returns to the left side of the heart, ready to be pumped to the brain and the rest of your body. Some people are born with a heart that has not developed properly in the womb before birth – these are called congenital heart defects. Where the atria meet the ventricles, there is an area of special cells called atrioventricular nodes that transmit electrical signals through a system of electrical pathways known as a conductive system through your heart muscle. The cardiac cycle refers to all the events that occur from the beginning of a heartbeat to the beginning of the next and can be divided into two parts: a period of relaxation known as diastole and a period of contraction known as systole. The changes in pressure and volume that occur during the cardiac cycle of the left ventricle are illustrated in Figure 6.2 and serve as a platform to describe important events. It is important that these changes for the left ventricle shown here also occur simultaneously in the right side of the heart in the right atrium, in the right ventricle and in the pulmonary artery. The standard pressure-volume loop for a single cardiac cycle is divided into four phases. Phase I is called the filling period and begins at point A when diastolic filling begins.
is also a founding member of Hi-Ethics. This website complies with the HONcode standard for reliable health information: Check here. Feeling your pulse can also help you determine if your heart rate is regular or not. Despite this new appreciation of the importance of systole and diastole in maintaining normal cardiovascular physiology, the role of diastolic LV function in health and disease is incompletely understood and underestimated by many primary care physicians and cardiologists. As discussed in Chapter 2, diastole is a complex phenomenon with many determinants that are difficult to study individually and several phases that include both relaxation and filling of the ventricle. Physical examinations, echocardiography (ECG), chest x-rays and laboratory studies are not reliable for diagnosing diastolic heart failure in most individuals, and invasive measurements of the diastolic properties and pressures of LV are not practical in clinical practice. Therefore, the assessment of the type and degree of diastolic dysfunction of the VL currently depends on the evaluation of the filling model of the VLT. Although this can be achieved through radionuclides and computed tomography (CT), angiographic imaging techniques and magnetic resonance imaging (MRI), cardiac ultrasound is currently the method of choice due to its non-invasive and portable nature. Evaluation of LV filling with two-dimensional anatomical results, Doppler flow and tissue Doppler imaging (TDI) has proven to be a powerful clinical technique for predicting adverse cardiovascular events such as emerging atrial fibrillation and heart failure, as well as LVEF-independent mortality. The purpose of this chapter will be to describe the different models of LV filling found in clinical practice and what these models and their measurable variables say about the diastolic function of lv..