ECG of the Month:Changing Morphology of a Wide-QRS Tachycardia.

An obese 49-year-old man with a history of systemic arterial hypertension, diabetes mellitus, dyslipidemia, three myocardial infarcts, an ischemic cardiomyopathy, a four-vessel coronary artery bypass operation 7 years earlier, and implantation of a cardioverter-defibrillator 2 years earlier comes to the hospital with palpitations and dyspnea. An ECG is recorded.

ECG of the Month:A Forty-Year-Old Woman with a History of a Cardiac Operation at Age 5 Years.

There is a sinus P wave in front of each QRS, and the rate is 122 beats/min. The QRS voltage is large and meets many criteria for left ventricular hypertrophy: RI > 13 mm (1.3 mV); RaVF > 19 mm; SaVR > 14 mm; SV1 > 24 mm; SV2 > 30 mm; RV6 > 26 mm; RV6 > RV5; SV1 + RV5 or RV6 > 35 mm; SV2 + RV5 or RV6 > 45 mm; RaVL + SV3 > 20 mm in a woman.

ECG of the Month: ECG in a 30-Year-Old Woman.

Sinus rhythm; an atrial premature complex; sagging ST-segments, low T-waves, and prominent U-waves suggesting hypokalemia. The ST-T and U-wave changes described above are characteristic of hypokalemia. When the serum potassium level is between 3.

ECG Case of the Month: IRREGULARLY IRREGULAR CARDIAC RHYTHM IN AN 87-YEAR-OLD WOMAN. MULTIFOCAL ATRIAL TACHYCARDIA; RIGHT BUNDLE BRANCH BLOCK.

Multifocal atrial tachycardia; right bundle branch block. The rhythm is totally irregular at a rate of 103 beats/min and originally was read as atrial fibrillation. Close examination, however, reveals a P wave before each QRS and ≥ 3 different P- wave morphologies with no dominant morphology.

ECG of the Month: ECG in an 81-Year-Old Woman.

Sinus bradycardia (48 beats/min), long P-R interval (0.29 s), long QT interval (0.53 s with QTc of 0.