Cats

The pathogenesis and symptoms of feline heart failure, common diseases in cats! Feline heart failure is also called cardiac insufficiency. It is not an independent disease and often occurs secondary to the occurrence of other diseases. , is a syndrome caused by weakened myocardial contractile function, resulting in reduced cardiac blood output, insufficient tissue perfusion, blocked venous return, edema, dyspnea, cyanosis, and even cardiac arrest and sudden death. According to the course of the disease, it can be divided into acute and chronic types. Chronic heart failure is also called congestive heart failure.

1. Pathogenesis

Cardiovascular has strong compensatory capacity, which under normal circumstances is enough to complete 5-6 times the normal load of the heart. Cardiac output tasks, animals that usually lack exercise, when suddenly severely exerted or exercised violently, the blood demand and venous blood return volume of various tissues and organs of the body increase sharply. In order to discharge more blood, the heart adapts to various tissues and organs The demand must be compensated by strengthening myocardial contractility and accelerating myocardial contraction frequency. Although strengthening myocardial contractility and accelerating myocardial contraction frequency can improve blood circulation to a certain extent in a short period of time, However, both can lead to excessive consumption of myocardial energy reserves and aggravate cardiac dysfunction. In particular, the accelerated frequency not only increases myocardial oxygen consumption, but also greatly shortens the ventricular diastolic period, resulting in insufficient ventricular filling and reduced coronary blood flow. The cardiac output not only does not increase but decreases, resulting in cardiac failure due to insufficient compensation. Exhaustion.

Acute heart failure is caused by weakened myocardial contractility, which reduces cardiac output and arterial pressure, which reflexively causes sympathetic nerve excitement and compensatory tachycardia. When the heart rate exceeds a certain limit, ventricular filling is insufficient, coronary blood flow decreases, and cardiac output decreases. Sympathetic nerve excitement causes the adrenal medulla to secrete a large amount of catecholamines (epinephrine, norepinephrine, etc.), causing spasmodic contraction of peripheral blood vessels, increasing ventricular pressure load, leading to cardiac congestion and insufficient renal blood supply, which reflexively causes the adrenal cortex to secrete aldosterone. And the antidiuretic hormone secreted by the hypothalamus-neurohypophysis increases, and the reabsorption of water and sodium ions by the renal tubules increases, causing water and sodium retention, increasing blood volume, aggravating the volume load of the ventricle and venous congestion, making heart failure more serious, and ultimately Acute heart failure occurs due to decompensation.

Congestive heart failure is common in endocardial diseases (bacterial endocarditis, congenital endocardial fibroelastosis), myocardial diseases (feline cardiomyopathy, infective myocarditis), Pericardial diseases (constrictive pericarditis, pericardial tumors), congenital heart defects (atrial or ventricular septal defects, aortic or pulmonary valve stenosis, patent ductus arteriosus, etc.), infections (parvovirus infection, trypanosomiasis, feline Infectious peritonitis), shock, endotoxemia, etc.

2. Symptoms

Congestive heart failure has a chronic course. Sick cats become tired after slight exercise or even excitement, depression, weight loss, pale or cyanotic conjunctiva. Cough and dyspnea occur with pulmonary congestion or pulmonary edema. Some have ascites and subcutaneous edema. Heart examination shows tachycardia, cloudy heart sounds, enhanced first heart sound and weak second heart sound, often loud heart murmur and precordial tremor, arrhythmia, and weak pulse. It can be seen on the electrocardiogram that the duration of the QRS complex is prolonged or the peaks are split due to ventricular enlargement, often accompanied by premature atrial or ventricular contractions, paroxysmal tachycardia, atrial fibrillation and atrioventricular block. X-ray examination often shows changes in cardiac hypertrophy, pulmonary congestion or pleural effusion.

When left heart failure occurs, in addition to the above signs, there are often severe dyspnea, coughing, colorless or pink foamy liquid flowing from the nostrils, and chest auscultation showing widespread rales and other pulmonary congestion and symptoms. Manifestations of pulmonary edema.

In 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.