Atrial pump loss of ventricular contraction

Atrioventricular block refers to the block of impulse during atrioventricular conduction. Divided into two categories of incompleteness and completeness. The former includes first-degree and second-degree atrioventricular block, and the latter is also called third-degree atrioventricular block, and the block can be in the atrium, atrioventricular node, Heath bundle and double bundle branch. In complete atrioventricular block, the temporal relationship between the atrium and the ventricle is separated, and the auxiliary pump function of the atria on ventricular contraction is lost, resulting in a decrease in cardiac output. Patients with complete atrioventricular block are more than 50 years old. In young patients, complete atrioventricular block is temporarily more. More men than women. Symptoms and hemodynamic changes of complete atrioventricular block depend on the degree of slowdown of ventricular rate and myocardial disease and functional status. In complete atrioventricular block, the temporal relationship between the atrium and the ventricle is separated, and the auxiliary pump function of the atria on ventricular contraction is lost, resulting in a decrease in cardiac output. In congenital complete atrioventricular block, the ventricular rhythm point is often above the branch of the atrioventricular bundle, the ventricular rate is faster, and it can increase with physical activity. Myocardial function is good, and cardiac output is easy to increase, so these patients often have no obvious symptoms. In patients with acquired complete atrioventricular block, most of them may be asymptomatic or have palpitation at rest. There may be palpitations, dizziness, fatigue, chest tightness, and shortness of breath during physical activity. If the ventricular rate is too slow, especially if the heart has significant ischemia or other lesions at the same time, or if it is complicated by extensive acute myocardial infarction or severe acute myocarditis, the symptoms may be severe, and heart failure or shock may occur, or due to insufficient blood supply to the brain The occurrence of unresponsiveness or obscurity, and then developed into syncope (incidence rate up to 60%), Alzheimer's syndrome. Due to the increase in diastolic ventricular filling and stroke volume, widening of the pulse pressure difference and mild to moderate cardiac enlargement can occur. The clinical manifestations of complete atrioventricular block during acute myocardial infarction have its own characteristics: the degree of hemodynamic disorder during acute myocardial infarction depends on the location of the infarction, the rate at which the block occurs, and the rate of ventricular pacing Site and ventricular rate. Inferior wall infarction is complicated by third-degree atrioventricular block. If it gradually develops from first-degree or second-degree ventricular atrioventricular block, the ventricular rate is not too slow, which may not cause clinical deterioration. In contrast, most anterior wall infarctions with third-degree atrioventricular block can cause hypotension, shock, and severe left heart failure. Regardless of anterior or inferior wall infarction, if the QRS wave widens suddenly and the ventricular rate is too slow, those with third-degree atrioventricular block below 40 beats / min are likely to induce ventricular arrest or ventricular tachycardia or Ventricular fibrillation. The mortality rate of anterior wall compared with inferior myocardial infarction with complete atrioventricular block is 2 times higher. However, when the inferior wall is combined with right ventricular myocardial infarction and complete atrioventricular block, the right ventricle's filling effect on the left ventricle is reduced, leading to a further decrease in cardiac output, hemodynamic disorders, and a significant increase in mortality. Complete atrioventricular block with acute myocardial infarction is mostly temporary, and only a few patients never recover after infarction. Those with slow ECG central ventricular rate and obvious QRS wave widening are particularly prone to syncope or heart failure. In patients with complete atrioventricular block, the first heart sound varies, and sometimes it is particularly loud, such as the firing sound. This is because the correlation between the atrial and ventricular systolic time often changes.