Pathophysiology of heart failure in dogs and cats

Clinical heart failure in dogs and cats occurs when the heart is either unable to adequately deliver blood for the body’s metabolic demands or when it can do so only with elevated filling pressures. Dog heart failure is not a specific diagnosis, but a syndrome caused by one or more underlying processes. Poor myocardial contractility (systolic disfunction), as a primary cause, can initiate the cascade of neurohormonal and other responses that result in clinical failure. However, other causes of chronic cardiac stress or injury can underlie the development of circulatory congestion and secondarily lead to myocardial systolic (and/or diastolic) dysfunction.

Chronic heart failure in dogs and cats cannot be framed simply and only in terms of a ”bad pump” that needs positive inotropic stimulation and a diuretic, although this therapeutic approach may be transiently necessary in some cases of acute, decompensated myocardial failure. The pathophysiology of the failing heart is much more complex and involves a number of structural and functional changes within cardiac and vascular cells, as well as within the extracellular matrix. The syndrome of heart failure can be viewed in terms of progressive ventricular remodeling that develops secondary to a cardiac injury or stress such as valvular disease, genetic mutations, acute inflammation, ischemia, incresed systolic pressure load, and other uses.

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