…to the sequence of activation of the ventricular myocardium. The ventricles should be depolarized (activated) by impulses spreading through the left and right bundle branch…

…Hypertrophy manifests on the ECG as increased amplitudes of the QRS complexes. The explanation is straightforward: myocardial muscle mass is increased and therefore it generates…

…80% of cases. Other causes include acute mechanical complications—particularly ventricular septal defect (VSD) and papillary muscle rupture with acute severe mitral regurgitation—predominant right…

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…

…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…

…g ejection fraction (EF), fractional sorting (FS), etc — do not elucidate regional variations in contractile function, or the effectiveness of longitudinal, radial, and circumferential contraction…

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

…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)…

…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…

…defined as regional abnormalities in contractile function. Ischemic heart disease is the most common cause of wall motion abnormalities. Assessment of wall motion abnormalities is…

…low concentration of gap junctions in AV nodal cells), which allows for ventricular filling to complete prior to ventricular contraction. In contrast, contractile cells–and…

…differences in contractile function. Otherwise, the point of measurement may not be representative. Ventricular activation must be normal. For example, in the setting of left…

…7 ). The explanation for this is as follows: The vector resulting from activation of the right ventricle does not come to expression , because it is…

…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…

…of the examination. Evaluation and Physical Examination Before stress echocardiography, clinical assessment should establish: The nature and stability of symptoms Exercise capacity The presence of…

…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…

…contractions (PAC) PACEMAKER RELATED Pacing with rapid ventricular response rate The incidence of tachycardia induced cardiomyopathy is 8–10% among patients with atrial tachycardia (Medi…

…Ventricular rhythm. One exception to the rule above should be noted. If an ectopic focus arises in or near the bundle of His, the impulse…

…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…