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

…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…

…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…

…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…

…Figure 1A 2C. The orientation of myocardial muscle fibers results in longitudinal, radial and circumferential shortening (contraction). Traditional methods for investigating left ventricular function — e…

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

…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…

…25% Normal FS, 2D measurement 18% Advantages of fractional shortening If ventricular geometry is normal and there are no regional wall motion abnormalities, then fractional…

…to the left and downwards ( Figure 7 ). The explanation for this is as follows: The vector resulting from activation of the right ventricle does not…

…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…

…block morphology is more common (regardless of heart rate) among persons with heart disease. Alternating block (right and left bundle branch block alternating from one…

…node) and intrinsic automaticity The sinus node is a small oval structure located near the entrance of the superior vena cava in the right atrium…

…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…

…syndrome, stress testing may be considered after at least 24 hours of stabilization, provided that active ischaemia and haemodynamic or electrical instability are absent. A…

…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…

…be caused by any tachyarrhythmia leading to prolonged periods of rapid ventricular rate (Table 1). Children and healthy adults may also develop tachycardia induced cardiomyopathy…

…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…

…to calculate; if the left ventricle contains 100 ml of blood at the end of diastole and 40 ml is pumped out during systole, then…

…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…