Congestive heart failure contractility increase

In summary, cardiac glycosides increase contractile force and reduce heart rate and AV conduction. In addition, cardiac glycosides suppress the sympathetic hyperactivity which occurs in advanced stages of congestive heart failure via a complex mechanism involving the central nervous system. 

Dopamine and dobutamine are sometimes used to stimulate the heart in cases of acute or severe heart failure (see Chapter 20). Dopamine and dobutamine exert a fairly specific positive inotropic effect, presumably through their ability to stimulate beta-1 receptors on the myocardium.60 Other beta-1 agonists (epinephrine, prenalterol, etc.) will also increase myocardial contractility, but most of these other beta-1 agonists will also increase heart rate or have other side effects that prevent their use in congestive heart failure. Dopamine and dobutamine are usually reserved for patients with advanced cases of congestive heart failure who do not respond to other positive inotropic drugs (e.g., digitalis).6,72... 

PHARMACOLOGICAL EFFECTS The adrenergic agonists lower arterial pressure by an effect on both cardiac output and peripheral resistance. In the supine position, when the vascular sympathetic tone is low, the major effect is to reduce both heart rate and stroke volume however, in the upright position, when sympathetic outflow to the vasculature normally increases, these drugs reduce vascular resistance and may lead to postural hypotension. The decrease in cardiac sympathetic tone leads to reduced myocardial contractility and heart rate, possibly promoting congestive heart failure in susceptible patients. 

C) Atrial natriuretic peptide increases cardiac contractility in congestive heart failure... 

Digoxin (Lanoxin) slows the heart rate and increases the contractility of the cardiac muscle and is used to treat atrial dysrhythmias or congestive heart failure, not premature ventricular contractions. 

Heart failure is a clinical syndrome of which a diseased heart is the centerpiece. It is characterized by the inability of the heart to meet metabolic demands. One may look at the preload, afterload, and contractility components associated with cardiac function in health and disease being affected by this syndrome. Congestive heart failure may be caused by a deficit of cardiac contractility or an increased workload. 

The main effect of hawthorn is on the cardiovascular system. Pharmacological studies report enhanced coronary blood flow and myocardial perfusion improvement of cardiac muscle contractility increased left ventrical output velocity lowering of blood pressure " an antiarrhythmic effect increased myocardium tolerance to oxygen deprivation under hypoxic conditions cardioprotective effect against myocardial infarc-tion and stimulation of revascularization after myocardial ischemia (escop 1) Various clinical studies reveal efficacy in congestive heart failure increased cardiac performance decrease in peripheral vascular... 

Theophylline, given as the soluble ethylenediamine salt aminophylline, offers some help in relieving the paroxysmal dyspnea that is often associated with left heart failure. A major portion of its efficacy may be due to the relief of bronchospasm secondary to pulmonary vascular congestion. Theophylline increases myocardial contractile force and has occasionally been used in the treatment of refractory forms of congestive heart fail-... 

Heart failure is due to defects in cardiac contractility (the vigor of heart muscle), leading to inadequate cardiac output. Signs and symptoms include decreased exercise tolerance and muscle fatigue, coupled with the results of compensatory responses (neural and humoral) evoked by decreases in mean BP. Increased SANS activity leads to tachycardia, increased arteriolar tone T afterload, 4- output, 4 renal perfusion), and increased venous tone (T preload, T fiber stretch). Activation of the renin-angiotensin system results in edema, dyspnea, and pulmonary congestion. Intrinsic compensation results in myocardial hypertrophy. These effects are summarized in Figure IH-4-1. 

In heart failure following a myocardial infarct, amrinone, digoxin, and dopamine (at high dose) can improve cardiac function (and relieve pulmonary congestion) by exerting a positive inotropic effect they each increase cardiac contractility. Amrinone, and at lower doses dopamine, may also cause vasodilation that can... 

Sulmazole (AR-L 115) (37), an imidazopyridine derivative, increased dp/dt max. by 58% and heart rate by 12 beats/min in anesthetized cats after 1 mg/kg i.v. Systolic blood pressure was decreased by 13 mm Hg.l42 Oral administration augmented dp/dt max. up to 92% for 5 to 12 hours in conscious dogs.143 Despite similar PDE-inhibitory activity of 37 and theophylline, it seems likely that effects other than PDE-inhibi-tion contribute to the positive inotropic action.144 Measurement of the effect of 21 on relations between free Ca++, bound Ca ", and ATPase activity of dog cardiac myofibrils indicates that the positive inotropic actions may involve direct activation of myofibrils by an increased affinity of thin filament receptors for Ca++.145 Several clinical studies in heart failure showed that in patients with congestive cardiomyopathy and with coronary artery disease, 22 improved hemodynamics and regional wall motion via decrease in pre- and afterload and Increase in contractility, myocardial oxygen consumption and coronary sinus flow, with no myocardial ischemia.14 149... 

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