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Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, in particular the large arteries and small arterioles. The process is the opposite of vasodilation, the widening of blood vessels. The process is particularly important in controlling hemorrhage and reducing acute blood loss.
A heart attack can cause arrhythmias, as well as permanent damage to the heart muscle. [25] Coronary ischemia resulting from coronary artery disease also increases the risk of developing heart failure. [10] Most cases of heart failure result from underlying coronary artery disease. [10]
Ventricular escape beats occur when the rate of electrical discharge reaching the ventricles (normally initiated by the heart's sinoatrial node (SA node), transmitted to the atrioventricular node (AV node), and then further transmitted to the ventricles) falls below the base rate determined by the rate of Phase 4 spontaneous depolarisation of ventricular pacemaker cells. [1]
Coronary artery disease (CAD), also called coronary heart disease (CHD), or ischemic heart disease (IHD), [13] is a type of heart disease involving the reduction of blood flow to the cardiac muscle due to a build-up of atheromatous plaque in the arteries of the heart. [5] [6] [14] It is the most common of the cardiovascular diseases. [15]
In a healthy heart all activities and rests during each individual cardiac cycle, or heartbeat, are initiated and orchestrated by signals of the heart's electrical conduction system, which is the "wiring" of the heart that carries electrical impulses throughout the body of cardiomyocytes, the specialized muscle cells of the heart.
Heart disease is the number one killer of men and women in the United States—it kills more people than all cancers combined, and is responsible for one out of every four deaths, according to the ...
Coronary thrombosis is defined as the formation of a blood clot inside a blood vessel of the heart. This blood clot may then restrict blood flow within the heart, leading to heart tissue damage, or a myocardial infarction, also known as a heart attack.
However, structural changes in the diseased heart as a result of inherited factors (mutations in ion-channel coding genes, for example) cannot explain the sudden onset of cardiac arrest. [60] In ventricular tachycardia, the heart also beats faster than normal, which may prevent the heart chambers from properly filling with blood. [61]