[Atrial natriuretic factor in acute atrial hyperkinetic arrhythmia and chronic atrial fibrillo-flutter]

The aim of this paper was to study atrial natriuretic factor, plasma renin activity and antidiuretic hormone values during paroxysmal atrial arrhythmias with different ventricular rates before and after pharmacological cardioversion and during chronic atrial flutter-fibrillation. The study was carried out: 1) during acute arrhythmias (atrial flutter-fibrillation or supraventricular tachycardia) and after restoration of normal sinus rhythm in 2 patients without heart disease, in 13 with chronic heart disease and in 6 with acute myocardial infarction; 2) during chronic atrial flutter-fibrillation in 5 patients with chronic ischemic heart disease, without congestive heart failure. Atrial natriuretic factor, aldosterone, plasma renin activity and antidiuretic hormone values were measured by radio-immunoassay. During paroxysmal atrial arrhythmias atrial natriuretic factor levels were higher than normal in all patients, particularly in those with supraventricular tachycardia. Most of the aldosterone measurements were above the normal range. As far as plasma renin activity and antidiuretic hormone values are concerned, levels higher than the normal range were found in the patients with severe hemodynamic impairment. Central venous pressure was above normal in all patients except in the 2 without heart disease, and there was a positive correlation between atrial natriuretic factor and central venous pressure values. After restoration of normal sinus rhythm atrial natriuretic factor values returned to normal except in acute myocardial infarction patients, in 1 chronic ischemic heart disease patient with congestive heart failure and in 3 patients with mitral valve disease. In all patients with chronic atrial flutter-fibrillation and in 5 patients with acute atrial flutter-fibrillation and low rate, above normal atrial natriuretic factor values were found with normal central venous pressure values. Atrial distension due to high central venous pressure values, lack of atrial contraction and rhythmic detension of the atrial stretch receptors, may be considered the major stimuli responsible for atrial natriuretic factor release during acute paroxysmal atrial arrhythmias and atrial flutter-fibrillation with low ventricular rate, respectively.