Hypopotassemia Resembling Myocardial Ischemia

ELECTROCARDIOGRAM OF THE MONTH

Hypopotassemia Resembling Myocardial Ischemia* MICHAEL M. LAKS , M .D. AND STEPH EN

R.

ELEK, M.D. , F.C.C .P.

Los Angeles, California

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fering from dehydration, nausea, drowsiness, and with a history of possible hysterical paralysis. As part of a medical checkup, an electrocardiogram, shown in Fig. lA, was ob-

3 3 - V E AR- O LD WHITE WOMAN WAS AD-

mitted to the Psychiatric Service suf-

*From the Department of Medicine and Institute for Medical Research, Cedars-Sinai Hospital.

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LAKS AND ELEK

tained. In this tracing, the ST segments are horizontally and deeply depressed in leads V 1 through V II and lead'S I, II, III and aVF. Since these changes resembled subendocardial injury , a diagnosis of coronary artery disease was made. However, hypokalemia was considered because the profoundly depressed ST segments are shorter in duration than is usually seen in myocardial ischemia. The serum potassium was 1.8 mEq.jL. This degree of ST segment change is associated with a low serum potassium concentration usually below 2.5 mEq.jL. In hypokalemia, the P waves are usually taller than normal and slightly peaked, best seen in the standard leads; similar P wave changes may also be seen in other conditions. It is interesting that Prinzmetal has demonstrated that the underlying mechanism for ST segment depression in mild ischemia is intracellular flux of potassium. After the intravenous administration of 40 mEq.jL. of potassium in about one hour, the electrocardiogram shown in Fig. IB was obtained. The ST segments were considerably less depressed, the P waves were diminished in amplitude and the V

Diseases of the Chest

waves, best seen in leads V 2 through V~, became more prominent. The normal Q-T interval and prolonged Q-V interval is characteristic of hypokalemia, as is the juxtaposition of the V wave to the T wave. These changes are best seen in the precordial leads. Left ventricular hypertrophy often produces V waves and the depressed ST segments in the left precordial leads, but of a different configuration from hypotassemia. In the presence of both left ventricular hypertrophy and hypopotassemia, the ST segment also become'S depressed in leads VI to v; It is worth emphasizing that the characteristic changes of hypokalemia are the depressed ST segments of short duration and prominent V-waves juxtapositioned to the T waves. Inasmuch as the electrocardiographic diagnosis of hypopotassemia is often missed, and since this is a treatable condition , it is important that the cardiologist be aware of the subtle electrocardiographic changes in hypotassemia. For reprints, please write Dr. Laks, 4833 Fountain Avenue, Los Angeles.

Readers are invited to submit art icles for the Electrocardiogram of the Month. Please submit material to Stephen R. Elek, M.D ., 6423 W ilshi re Bouleva rd. Los Angeles, California.

RADIOCINEMATOGRAPHIC INVESTIGATION The author's experience In clinical radloclnematography of the esophagus testlftes to the fact that the study of the contractile capacity of esophageal walls In the diagnosis and differential diagnosis of tumors of the esophagus merits great attention. An a na lys ls of segmental contractions Is of greater slgnlftcance than the assessment of peristaltic movements. According to the author. the undervaluation of th e diagnostic Importance oC segmental contrae-

tlons of the esophagus at the present time Is due to the complex nature of their study during routine x-ray Investigation. Radloclnematography with Its peculiarities and possibilities opens new vistas in this d irection. KE\'ESH , L. E. : " Importance of Analys is of Segmental Contractions of the Esophagus in the Diagnos is of its Tumorous Affections (Radiocinematographic Investigation) ," Clin, M,d. ( USSR ) , 42 :4~, 1964.

CONGENITAL DIAPHRAGMATIC HERNIA A 45-year-old woman was referred to the surgical clinical for evaluation of abnormal chest roentgenogram. Chest film revealed a round tumor-like dense opacity adjacent to the heart In the lower field of the right lung. Lateral film disclosed the shadow behind the sternum. On t1uroscopy, there was noted a clear area In the shadow and careful auscultation reveuled occasional Intestinal sound over the right

hemithorax. On thoracotomy, parasternal hernia (Morga gn l) containing the omentum and a portion of the transverse colon was found and was repaired after a large portion of the omentum was excised. INADA, K. ET AL: "Congenital D iaphr agmatic Hern ia : A Case Report of Parasternal Hern ia Cured Surgically," I"P""'st I. Thor. S"rg .. 17 :49, 1964.