…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…

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

…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…

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

…of cardiac cells: Conduction cells form the fiber networks that sprout into the myocardium and disseminate the action potential. These cells have virtually no contractile…

…of such changes is simply to enable the cardiopulmonary system to increase its delivery of oxygen to skeletal muscle and myocardium. The oxygen consumption – and…

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

…are components of the myocardial contractile apparatus and are expressed predominantly in cardiac muscle. Troponin I is highly specific for myocardial injury. Interpretation of troponin…

Echocardiography Echocardiographic assessment of regional contractile function Systolic ventricular function is one of the strongest predictors of total and cardiovascular mortality. Previous chapters have discussed…

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

…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 )…

…concentration after induction of ventricular fibrillation (cardiac arrest). As ATP concentration declines, critical cell functions cease. Membrane potential, action potential, excitability, and contractile function are…

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

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

…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…

…Elsevier 2010 ). At the time of J 60 and J 80, there is minimal chance that there are any electrical potential differences in the myocardium…

…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…

…contractile force (contractility). Several endogenous and synthetic agents exist and are frequently combined to achieve the desired hemodynamic outcome. Most agents exhibit both vasopressor and…

…contractile force (contractility). Several endogenous and synthetic agents exist and are frequently combined to achieve the desired hemodynamic outcome. Most agents exhibit both vasopressor and…

…ischaemia and to estimate prognosis in patients with suspected or established coronary artery disease (CAD). It combines echocardiographic assessment of left ventricular (LV) structure and…

…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…

…the main cause of left ventricular dysfunction among patients with atrial fibrillation and other supraventricular tachyarrhythmias. Moreover, ventricular tachyarrhythmias (including recurrent episodes of ventricular tachycardia…

…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…

…major determinants of subsequent LV deterioration and long term survival. Viable, stunned, and hibernating myocardium Viable dysfunctional myocardium is myocardial tissue whose contractile function improves…

…that variations in preload and afterload, rather than changes in contractile function, explains the varying ejection fraction. Ejection fraction and left ventricular volume Ejection fraction…

…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…