…aorta. Afterload affects myocardial muscle fibers during systole and diastole. Afterload is a function of the following three variables: Aortic resistance (pressure). Left ventricular volume…

Echocardiography Structure and contractile function of myocardial fibers The left ventricular wall can be subdivided into several layers. These layers are similar to those seen…

…The orientation of myocardial muscle fibers results in longitudinal, radial and circumferential shortening (contraction). Traditional methods for investigating left ventricular function — e.g ejection fraction…

…of them are easy to use and require very little calculation. Sensitivity and specificity vary markedly, as discussed in detail in the articles on left…

…severe left ventricular (LV) dysfunction, accounting for approximately 80% of cases. Other causes include acute mechanical complications—particularly ventricular septal defect (VSD) and papillary muscle…

…and the development of myocardial fibrosis. Contractile dysfunction further aggravates the regurgitation (the regurgitation volume increases). Mechanically, wall stress (the load on individual muscle fibers)…

…ventricles. When the contractile myocardium receives the action potential, it is activated and contracts. Figure 1 illustrates the relevant components of the conduction system, the…

…as follows: Sympathetic activity causes constriction of the veins, which increases the venous return to the heart. Contracting muscles function as a pump that propels…

…degradation. Histologically, a vulnerable plaque is defined by a fibrous cap thickness of less than 65 μm, heavy macrophage infiltration, sparse smooth muscle c

…injury. Mechanisms of troponin release Troponin I and troponin T are components of the myocardial contractile apparatus and are expressed predominantly in cardiac muscle. Troponin…

…of the Left Ventricle). Regional wall motion abnormalities are defined as regional abnormalities in contractile function. Ischemic heart disease is the most common cause of…

…the ventricles. First degree AV block is rarely serious and may be left untreated in the vast majority of cases (exceptions are discussed later). Second…

…the following reasons: Left ventricular geometry must be normal. There must not be regional differences in contractile function. Otherwise, the point of measurement may not…

…third vector: the ventricular free wall The vectors resulting from activation of the ventricular free walls is directed to the left and downwards ( Figure 7 )…

…excitability, and contractile function are all compromised by ATP depletion. Myocardial necrosis (infarction) commences within 20 minutes of circulatory collapse. The electrical phase: Defibrillate It…

…systolic function (contractile function) Several echocardiographic measurements are available to assess left ventricular systolic function. These methods elucidate slightly different aspects of systolic function and…

…conduction and contractile cells—must undergo rapid repolarization to ensure they are excitable when the next action potential occurs. If any component of the ventricular…

…contractile myocardium. When the contractile myocardium receives the action potential, it is activated and contracts. Figure 1 illustrates the sinus node and the components of…

…J point to the onset of the T wave. Because of the long duration of the plateau phase most contractile cells are in this phase…

…heart rate and contractility (i.e contractile force), results in increased metabolism. Cardiac cells are highly capable of matching the supply and demand of ATP…

…Vasopressors induce vasoconstriction and increase mean arterial pressure (MAP). Inotropes increase cardiac contractile force (contractility). Several endogenous and synthetic agents exist and are frequently combined…

…Vasopressors induce vasoconstriction and increase mean arterial pressure (MAP). Inotropes increase cardiac contractile force (contractility). Several endogenous and synthetic agents exist and are frequently combined…

…coronary artery disease (CAD). It combines echocardiographic assessment of left ventricular (LV) structure and function with exercise or pharmacological stress. The physiological basis is an…

…This makes more calcium available to the contractile proteins which therefore produce stronger contractions. Lowering of the heart rate is due to increased Vagus nerve…

…of His, bundle branches (left and right bundle branch), and Purkinje fibers. The conduction system allows for rapid spread of the depolarization to the contractile…

…for electrophysiological evaluation (Hasdemir et al, Kawamura et al, Yokokawa et al). Tachycardia induced cardiomyopathy is presumably the main cause of left ventricular dysfunction among…

…of ventricular rhythm and idioventricular rhythm The usual mechanisms are responsible for all ventricular rhythms. Increased automaticity (in His Purkinje fibers), abnormal automaticity (in contractile…

…moderate ischemia may produce post ischemic stunning. In the absence of infarction, contractile recovery can occur rapidly after reperfusion, with recovery generally occurring within one…

…Ejection fraction is routinely examined at rest, which does not reveal the functional (maximum) capacity of the left ventricle, as this would require measuring the…

…The action potential in the sinoatrial node and in contractile myocardial cells. Phase 4 of the action potential in the sinoatrial node is called "pacemaker…