Cardiac failure pathophysiology

Congestive Cardiac Failure Pathophysiology and Treatment, edited by David B. Barnett, Hubert Pouleur and Gary S. Francis... 

Dysautonomias also range from mechanistically straightforward disorders in which altered autonomic function plays a primary pathophysiological role (e.g., pure autonomic failure), to conditions in which altered autonomic fimction worsens an independent pathophysiological state (e.g., cardiac failure), and to more mysterious disorders in which the involvement of the autonomic nervous system is less clear (e.g., chronic fatigue syndrome). Abnormalities of blood pressure control represent the common presenting cfinical features of the dysautonomias. In those involving... 

Propofol infusion syndrome Propofol infusion syndrome has been reported in children and adults after short-term high-dose propofol. It presents with variations of severe metabolic acidosis, rhabdomyolysis, myoglobinuria, cardiac failure, and death. The pathophysiology is unknown, but genetic predisposition, mitochondrial inhibition, and increases in serum free fatty acids are believed to play a role. Catecholamines and corticosteroids may act as triggering agents. 

Pathophysiology can influence muscarinic activity in other ways as well. Circulating autoantibodies against the second extracellular loop of cardiac M2 muscarinic receptors have been detected in some patients with idiopathic dilated cardiomyopathy and those afflicted with Chagas1 disease caused by the protozoan Trypanosoma cruzi. These antibodies exert parasympathomimetic actions on the heart that are prevented by atropine. In animals immunized with a peptide from the second extracellular loop of the M2 receptor, the antibody is an allosteric modulator of the receptor. Although their role in the pathology of heart failure is unknown, these antibodies should provide clues to the molecular basis of receptor activation because their site of action differs from the orthosteric site where acetylcholine binds (see Chapter 2). 

The net result of the action of therapeutic concentrations of a cardiac glycoside is a distinctive increase in cardiac contractility (Figure 13-5, bottom trace). In isolated myocardial preparations, the rate of development of tension and of relaxation are both increased, with little or no change in time to peak tension. This effect occurs in both normal and failing myocardium, but in the intact patient the responses are modified by cardiovascular reflexes and the pathophysiology of heart failure. 

Hypercalcemia occurs in horses with chronic renal failure and in a few neoplastic conditions. The clinical signs are usually those of the underlying pathophysiology but soft tissue calcification may occur. In experimental ponies, hypercalcemia induced ventricular fibrillation or cardiac arrest at ionized calcium concentrations of 18.2-40mg/dl (4.55-10.0 mmol/1) (Glazier et al 1979). Treatment for severe hypercalcemia (ionized... 

To understand the pathophysiologic processes in heart failure, a basic understanding of normal cardiac function is necessary. Cardiac output (CO) is defined as the volume of blood ejected per unit time (L/min) and is the product of heart rate (HR) and stroke volume (SV) ... 

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