High-resolution and signal-averaged electrocardiography to separate post-myocardial infarction patients with and without ventricular tachycardia.

High-resolution and signal-averaged ECG, 24 h Holter recording and ejection fraction were used to separate post-myocardial infarction patients with and without ventricular tachycardia (VT) among 150 individuals: 26 patients with an old myocardial infarction and documented sustained VT, 104 patients with an acute myocardial infarction without sustained VT, who were followed-up for 2 years, and 20 healthy volunteers. Bipolar orthogonal XYZ leads were recorded, high-pass filtered at cut-off frequencies of 25, 40, 60, 80 and 100 Hz, and combined to vector magnitude square root of X2 + Y2 + Z2. The filtered QRS duration, the root-mean-square voltages of different time intervals and the durations of low amplitude signals under different thresholds, both from the initial and terminal QRS, were calculated.

Magnetocardiography: supraventricular arrhythmias and preexcitation syndromes.

Magnetocardiography is an elegant non-invasive method with which to study the electrical activity of the heart. The localization of cardiac electric sources, such as arrhythmia foci, would, in particular, be an interesting clinical application. In addition the detection of different abnormalities that could lead to cardiac depolarization and repolarization gives insight into how cardiac arrhythmias and arrhythmia mechanisms are generated.

Identification of patients with ventricular tachycardia after myocardial infarction by high-resolution magnetocardiography and electrocardiography.

The value of time domain analysis of late fields in the high-resolution magnetocardiogram in the identification of myocardial infarction patients with ventricular tachycardia was investigated in 30 subjects: 10 patients with documented sustained ventricular tachycardia and old myocardial infarction, 10 patients with old myocardial infarction without complex ventricular arrhythmias, and 10 normal volunteers. The duration of the QRS complex in the magnetocardiogram was significantly longer in ventricular tachycardia patients compared to myocardial infarction patients (144 (SD, 33) vs 109 (SD, 8) ms; p = 0.004).

The effects of thrombolytic therapy on the high-resolution electrocardiogram after myocardial infarction.

The effects of thrombolytic treatment was studied in 109 consecutive patients 9-11 days after their first acute myocardial infarction by high-resolution electrocardiography (ECG), 24 h Holter monitoring, exercise test and radionuclide ventriculography. Thirty-seven patients were treated with intravenous thrombolytic agents. Thrombolytic treatment was assessed by clinical criteria to be successful in 22 patients and probably successful in 12 patients.

Localization of accessory pathways in Wolff-Parkinson-White syndrome by high-resolution magnetocardiographic mapping.

Fifteen patients with Wolff-Parkinson-White syndrome were studied with standard 12-lead electrocardiogram, invasive electrophysiologic study, and high-resolution magnetocardiographic (MCG) mapping. In addition, intraoperative epicardial mapping was performed in seven surgically treated patients. The MCG characteristics of ventricular preexcitation for different locations of the atrioventricular accessory pathways were described in terms of morphology and field patterns.