Interatrial block (IAB) (P wave > or =110 milliseconds) is a potent correlate of atrial tachyarrhythmias, left atrial electromechanical dysfunction, and embolism. IAB has been demonstrated to be highly prevalent in the general hospital population, but no investigation has addressed this in the elderly community outside the hospital. We appraised the prevalence of IAB in a service of the Program of All-Inclusive Care for the Elderly (PACE), the Elder Service Plan (ESP). Of the 202 ESP members in Worcester, MA, 167 (ages 61-103 years; female 81.4%) who had current 12-lead electrocardiograms were evaluated for IAB, and an age-based comparison was made between those with and without IAB. Of those patients with current electrocardiograms, 148 (88.6%) showed sinus rhythm and 72 (48.6%) depicted IAB: 20% in patients aged 60-69 years, 39.5% aged 70-79 years, 56.8% aged 80-89 years, and 50% in those 90 years and older. Given its sequelae of anatomic and pathophysiologic consequences, prompt recognition of IAB in a high-risk group such as that in the PACE community (48.6% prevalence) is important, especially for anticipation of atrial fibrillation and possible embolism.

No abstract

T he ECG, taken in the emergency department (ED), of a 38-year-old woman with renal failure complaining of weakness is shown below. The extreme widening (up to 350 ms) of the QRS complexes and their almost sine wave connection to their T waves is one sign of acute hyperkalemia that is particularly valuable in the ED. The patient's serum potassium level was 8.7 mEq/L. With treatment, the patient's ECG was normal 8 hours later, with normal P waves and sinus rhythm (P axis, +50 degrees), a QRS duration of 78 ms, and a QRS axis of +60 degrees. (Hyperkalemia induces QRS axis shifts, but if this is not a supraventricular rhythm that is a moot point.) The ED trace showed an irregularly irregular rhythm with no sign of atrial activity (the "bumps" in beats 2, 3, 5, and 7 are probably part of the QRS). One cannot rule out any atrial rhythm because hyperkalemia suppresses P waves even with sinus rhythm by electrical "paralysis" of the atria. (With a regular ventricular rhythm, the sinus can control the ventricles with suppressed P waves [sinoventricular rhythm], but here atrial fibrillation cannot be ruled out.) Although the QRS complexes fulfill criteria for ventricular tachycardia, idioventricular rhythm cannot be ruled out, but it is less likely because of the degree of irregularity. The extreme QRS widening is rare in ventricular rhythms in the absence of hyperkalemia or certain drug effects (eg, encainide). With hyperkalemia, the ECG effects depend on the rate of rise of serum potassium more than its absolute level.

No abstract

T he patient was a 62-year-old heavy smoker who presented to the emergency department with acute dyspnea. Pulmonary function tests were subsequently positive for severe obstructive lung disease. The ECG shows a vertical (over +60 degrees) P-wave axis, which, by itself, is about 90% specific for emphysema in men and women older than 45 years. The vertical P axis induces a single-peaked P wave in leads II, III, and aVF. Lead II shows P pulmonale (P wave ≥2.5-mm amplitude), which is usually, as it is here, an emergency department phenomenon, disappearing with early treatment (NOTE: the vertical P axis is permanent). Another typical finding is narrow QRS complexes, shown here <70 milliseconds. The combination of vertical P axis and vertical narrow QRS was 96% specific for emphysema in a recent investigation. The peaked T waves are nonspecific, probably an adrenergic response.