Why does the heart beat prematurely

Premature heart beats may occur in normal people or in patients with some heart diseases. Premature heart beats may occur in various ways, including a person's careless lifestyle, frequent smoking and drinking, and no regular time to regulate oneself. These are the main factors that can cause premature heart beats, and some examination items need to be selected.

Causes

Premature beats can occur in normal people. But it is more likely to occur in patients with cardiac neurosis and organic heart disease. Emotional excitement, nervous tension, fatigue, indigestion, excessive smoking, drinking or drinking strong tea can all cause attacks. There may also be no obvious triggers. The toxic effects of digitalis, barium, quinidine, sympathomimetic drugs, chloroform, cyclopropane anesthetics, potassium deficiency, and heart surgery or cardiac catheterization can all cause attacks. Coronary heart disease, advanced mitral valve disease, heart disease, myocarditis, hyperthyroidism heart disease, mitral valve prolapse, etc. are prone to premature beats.

Pathogenesis

It may occur in a variety of ways.

(I) Abnormal impulse formation caused by abnormal autonomy ① Under certain conditions, such as when the sinus impulse reaches the ectopic pacemaker, due to the Weidensky phenomenon, the threshold potential at that point is lowered and the diastolic depolarization slope is changed, causing premature beats. ② The permeability of the diseased atrium, ventricle or pulsatile fiber cell membrane to different ions changes, causing the fast-response fibers to transform into slow-response fibers, thereby accelerating the automatic depolarization during diastole, enhancing autonomy, and producing premature beats.

(ii) Reentry phenomenon - circular reentry or focal microreentry. If the reentry pathway is the same, the morphology of the premature beat will be consistent; if the conduction velocity during the reentry is consistent, the pairing time of the premature beat with the previous beat will be fixed.

(III) Parallel contraction

4. Triggered activity

Clinical manifestations

Premature beats may be asymptomatic or may cause palpitations or a feeling of cardiac arrest. Frequent premature beats can cause symptoms such as fatigue and dizziness (due to reduced cardiac output). For people with existing heart disease, this can induce or aggravate angina pectoris or heart failure. Auscultation may reveal irregular heart rhythm and a long compensatory interval after premature beats.

The first heart sound of premature beats is often enhanced, while the second heart sound is often weakened or disappeared. When premature beats are in a binomial or tripeminic rhythm, a long pause can be heard after every two or three heartbeats. Premature beats are inserted between two regular heartbeats and may appear as three consecutive heartbeats. Palpation of the pulse may reveal intermittent absence of pulses.