The pathogenesis and symptoms of heart failure in cats, common diseases in cats! Heart failure in cats is also known as cardiac insufficiency. It is not an independent disease and is often relayed in the occurrence of other diseases. It is caused by weakened myocardial systolic function, resulting in reduced cardiac output, insufficient tissue perfusion, obstruction of venous return, edema, dyspnea, cyanosis, and even cardiac arrest and sudden death. According to the course of the disease can be divided into acute and chronic. Chronic heart failure is also known as congestive heart failure.

I. Pathogenesis

Cardiovascular It has a strong compensatory ability. Under normal circumstances, it is enough to complete the task of cardiac output that exceeds the normal load of the heart by 5-6 times. For animals that lack exercise, when suddenly heavy duty or strenuous exercise occurs, various tissues and organs of the body are required. Both blood volume and venous blood return volume have increased sharply. In order to discharge more blood and meet the needs of various tissues and organs, the heart must compensate by strengthening myocardial contractility and accelerating myocardial contraction frequency. Although the myocardial contraction frequency can improve blood circulation to a certain extent in a short period of time, both of them can lead to excessive consumption of myocardial reserve energy and aggravate cardiac dysfunction. Especially if the frequency is accelerated, it not only increases myocardial oxygen consumption, but also greatly shortens the ventricular diastolic period, insufficient ventricular filling and coronary blood flow, so that the cardiac output not only does not increase, but decreases. exhaustion.      

Acute heart failure is due to weakened myocardial contractility, which reduces cardiac output, arterial pressure, and reflexively induces sympathetic nerves Excited, compensatory tachycardia occurs. When the heart rate exceeds a certain limit, the ventricle is underfilled, coronary blood flow decreases, and cardiac output decreases. Sympathetic nerve excitation causes the adrenal medulla to secrete a large amount of catecholamines (epinephrine, norepinephrine, etc.), causing spasmodic contraction of peripheral blood vessels, aggravating ventricular pressure load, resulting in cardiac congestion and insufficient renal blood supply, which reflexively causes the adrenal cortex to secrete aldosterone and hypothalamic-neuropituitary secretion of antidiuretic hormone increased, renal tubular reabsorption of water and sodium ions increased, causing water and sodium retention, increasing blood volume, aggravating ventricular volume overload and venous congestion, promoting more serious heart failure, and ultimately Acute heart failure due to decompensation.

Congestive heart failure is commonly seen in endocardial disease (bacterial endocarditis, congenital endocardial fibroelastosis), myocardial disease ( , cat cardiomyopathy, infectious myocarditis), pericardial disease (constrictive pericarditis, pericardial tumor), congenital heart defect (atrial or ventricular septal defect, aortic or pulmonary valve stenosis, patent ductus arteriosus, etc.), infection (parvovirus infection, trypanosomiasis, feline infectious peritonitis), shock, endotoxemia, etc.

2. Symptoms

Congestive heart failure is chronic go through. Affected cats are fatigued, depressed, lose weight, and have pale or cyanotic conjunctiva on mild exercise or even excitement. Cough and dyspnea with pulmonary congestion or pulmonary edema. Some have ascites and subcutaneous edema. Cardiac examination revealed tachycardia, cloudy heart sounds, enhanced first heart sound and weak second heart sound, often loud heart murmurs and precordial tremors, arrhythmia, and weak pulse. On the electrocardiogram, the QRS complex wave can be seen to be prolonged or due to ventricular dilation and peak splitting, often accompanied by atrial or premature ventricular contractions, paroxysmal tachycardia, atrial fibrillation and atrioventricular block. X-ray examination often shows changes in cardiac hypertrophy, pulmonary congestion or pleural effusion.

In left heart failure, in addition to the above signs, there is often severe dyspnea, cough, colorless or pink foamy fluid from the nostrils, chest auscultation There are generalized wet rales and other manifestations of pulmonary congestion and pulmonary edema.

In the case of right heart failure, in addition to the above signs, there are often clinical signs such as conjunctival cyanosis, superficial venous distention, subcutaneous edema, hepatomegaly, and ascites. .