Echocardiographic measurements and plasma levels of atrial natriuretic factor

Atrial distension and pressure have been reported to be important for the release of atrial natriuretic factor (ANF) into the circulation. However, in mild essential hypertension, we have been unable to demonstrate an increase in plasma levels of ANF. To evaluate more precisely the lack of increase of ANF, we measured echocardiographically the diameters of the cardiac chambers and correlated these measurements with ANF values in normal subjects (n = 25), in patients with untreated essential hypertension (n = 20), and in patients with treated essential hypertension (n x 27). The plasma values of ANF were 21.9 +/- 2.8 pg/ml in the normal controls, 20.4 +/- 2.2 pg/ml in patients with untreated mild essential hypertension, and 32.6 +/- 2.8 pg/ml in patients with treated but uncontrolled essential hypertension (p less than 0.05). The plasma values of cGMP were 4.53 +/- 0.56 pmol/ml in the normal, 5.41 +/- 0.57 pmol/min in the patients with untreated essential hypertension, and 6.76 +/- 0.58 pmol/ml in treated essential hypertension (p less than 0.05). There were no significant differences in the size of the cardiac chambers between the three groups, except for the size of the right atrium, but there was a correlation between the ANF values and the size of the left atria (r = 0.29, p = 0.01, n = 72), as well as with the size of the intraventricular septum (IVS) in systole (r = 0.36, p = 0.002, n = 72). Since ANF levels are similar in mild untreated essential hypertension and normal volunteers, the ANF plasma levels could be a better reflection of the impact of the blood pressure on the myocardium than the level of blood pressure itself and indicate in patients the degree of cardiac impairment. On the other hand, there seems to be definitely an effect of treatment on the levels of ANF.