[Value of the study of electrocardiographic P wave in pheochromocytoma].

The diagnostic value of electrocardiographic P wave analysis in the frontal plane was assessed with respect to previously reported abnormalities: right atrial hypertrophy-dilatation; an enlarged, crenalleted summit without criteria of right atrial hypertrophy. Two observers studied the ECG recordings of 20 hypertensive patients with pheochromocytomas: 10 men and 10 women, aged 45.5 +/- 16 years, and in 30 patients with essential hypertension, 15 men and 15 women, aged 48.9 +/- 9 years (NS). The duration of hypertension was 2.6 +/- 2 years versus 4.7 +/- 4 years (p = 0.02). Right atrial hypertrophy-dilatation was observed in 5 patients in the pheochromocytoma group and in none of the essential hypertensive patients: an isolated abnormality of the summit of the P wave was observed in 5 other cases of pheochromocytoma and by 1 observer in 1 of the essential hypertension. These abnormalities disappeared after ablation of the tumour. These changes were not recorded in 3 patients who had predominant noradrenaline hypersecretion; nevertheless, comparison of the urinary adrenaline, noradrenaline, normeta- and metanephrine levels were inconclusive. No relationship was established between these concentrations, global urinary catecholamines and meta block, the duration of hypertension, the frequency and level of hypertensive crises, or the presence of "ischaemic" ST-T wave changes. P wave changes are thought to be related to high plasma catecholamine levels irrespective of the clinical impact; the sensitivity of these changes is modest (10/20) but the specificity is better within a group of hypertensive patients. An experienced observer can orient the diagnostic investigations to the search for a pheochromocytoma or to a secondary recurrence of the tumour from the surface ECG. The role of marker of a very high noradrenaline or adrenaline secretion cannot be confirmed from a series limited in separated plasma concentration measurements.