Relationship between arterial pressure and negative U waves in electrocardiograms.

A LTHOUGH HYPERTENSION is a common pathologic condition associated with negative U waves in the electrocardiogram, their clinical significance and relationship to arterial pressure have not been adequately established. Kemp et al.1 have described a correlation between negative U waves in left precordial leads and malignant hypertension with con-gestive heart failure. Reversal of the waves from negative to positive or isoeleetric has been noted after sympathectomy2 and, as reported by Surawiez, Kemp, and Bellet,a following the lowering of arterial pressure presumably with one of the antihypertensive agenits, administration of nitroglycerin, and incidental slowing of the heart rate. These observations suggest that inverted U waves in electrocardiograms of hypertensive patients might bear some relationship to the arterial pressure but do not make clear whether the level of the arterial pressure is the critical factor in determining their polarity. The present study was undertaken to determine the possible relationship between arterial pressure and degree of negativity of U waves in electrocardiograms of hyper-tensive patients and to evaluate their clinical significance. Methods and Material The active files of the Research Division of the Cleveland Clinic were reviewed. Records of hyper-tensive patients who have had negative U waves in one or more of the left precordial leads of the electrocardiogram and who, following anti-hypertensive treatment, had repeat electrocardi-ographic tracings constitute material for this study. A total of 45 records was selected. Fundus-copic examinations performed during each visit and arterial pressure measurements at least four times daily in supine and standing positions were available in all. Since arterial pressure measurements were not performed simultaneously eaclh electrocardiographic tracing, for purposes of coiii-parison, the average supine arterial pressure of that day was used. In addition, in 12 hypertensive patients, who on their recent admission to the Res~arch Ward of the Cleveland Clinic Hospital had negative U waves in one or more of the left precordial leads, the arterial pressure was lowered with intravenous sodium nitroprusside as previously described,4 and simultaneous electrocardiograms were taken serially. In each patient the arterial pressure, measured sphygmomiianoimietr ically every half minute, was kept, with the use of sodium nitroprusside, at various desired levels for as long as it was necessary to obtain electrocardio-graphic tracings. Only the leads showing the negative U waves were taken. In three of these 12 patients, electrocardiograms were also taken during and after intravenous infusion of guanethi-dine, in both supine and head-up tilt positions. Results Review of the …