A 71-year-old man with a history of previous myocardial infarction was referred to our hospital for recurrent symptoms of palpitation and syncope. During an episode of palpitations, a 12-lead ECG (Figure 1) was obtained in the emergency room. The ECG shows a wide-QRS complex tachycardia at a rate of 167 bpm. The P waves are positive in lead II (↑) before each QRS complex, and the PR interval is...

AIMS Cardiac resynchronization therapy (CRT) is an effective treatment for heart failure patients with prolongation of QRS duration. Despite careful patient selection, some do not respond to CRT based on QRS complex duration. We sought to evaluate the presence of left ventricular dyssynchrony using tissue Doppler imaging (TDI) according to QRS duration in heart failure patients. METHODS AND R...

The ability to evaluate various Electrocardiogram (ECG) waveforms is an important skill for many health care professionals including nurses, doctors, and medical assistants. The QRS complex is a vital wave in any ECG beat. It corresponds to the depolarization of ventricles. The duration, the amplitude and the complex QRS morphology are used for the purpose of cardiac arrhythmias diagnosis, cond...

We describe the case of a 67-year-old woman with non-ischemic dilated cardiomyopathy who underwent successful radiofrequency catheter ablation for ventricular tachycardia (VT) originated from the isolated ventricular septal substrate. Pacemapping exhibited either left, identical to clinical VT, or right bundle branch block like wide QRS morphology. Time interval from the stimulus to QRS onset (...

An electrophysiologic procedure was performed in a 50-year-old man with a 20-year history of paroxysmal tachycardia. During sinus rhythm, the atrial-His (AH) interval was 70 msec, the His-ventricular (HV) interval was 45 msec, and the QRS width was 80 msec. During atrial pacing at a cycle length of 290 msec, there was widening of the QRS complex (Fig. 1). The transition from a narrow to wide QR...

To determine if paced cycle length-dependent changes in the QRS duration correlate with the change in ventricular tachycardia (VT) cycle length after procainamide, we measured the QRS duration during sinus rhythm and during right ventricular pacing before and after procainamide (mean concentration, 9.9 micrograms/ml) in 18 patients with morphologically identical VT induced at both study periods...

Aims: To investigate the hypothesis that changes in the ECG over time may be an important and readily available marker of prognostic value in patients with heart failure. Methods: 112 elderly patients (81 men) with stable heart failure, a mean (SD) age of 73.3 (4.4) years, left ventricular ejection fraction 38 (17)%, and peak oxygen consumption 15.1 (4.7) ml/kg/min had ECG measurements on two o...

The QRS represents the simultaneous activation of the right and left ventricles, although most of the QRS waveform is derived from the larger left ventricular musculature. Although normal QRS duration is <100 millisecond (ms), its duration and shape are quite variable from patient to patient in idiopathic dilated cardiomyopathy (IDCM). Prolongation of QRS occurs in 14% to 47% of heart failure (...

The majority of patients with Duchenne muscular dystrophy (DMD) have electrocardiographic abnormalities, but the clinical significance of conduction disturbances remains unclear. This study aimed to evaluate age-dependent cardiac conduction disturbances by electrocardiogram (ECG) to identify risks of complete atrioventricular (AV) block in this patient population.In total, 47 patients with DMD ...

Prolonged electrocardiographic QRS duration is frequently observed in congestive heart failure (CHF) patients. We hypothesized that CHF risk increases with longer QRS interval in individuals free of CHF. We evaluated 1759 Framingham Study participants (mean age, 69 years; 63% women) without prior myocardial infarction or CHF who attended a routine examination. QRS duration was analyzed as a con...