[Disproportionate shortening of left ventricular diastolic duration in patients with dilated cardiomyopathy]. / Abnorme Verkürzung der linksventrikulären Diastolendauer unter körperlicher Belastung bei Patienten mit dilatativer Kardiomyopathie.

BACKGROUND AND PURPOSE: Cardiac performance can be characterized in terms of the relative duration of systole and diastole. In pediatric patients with dilated cardiomyopathy (DCM), a disproportionate shortening of left ventricular diastole was observed. The present study was intended to reproduce these findings in an adult patient group and to evaluate exercise-related changes of both time intervals. PATIENTS AND METHODS: Exercise radionuclide angiography was used in 61 patients with DCM NYHA (New York Heart Association) stage II-III. The phases of the cardiac cycle were derived from a radionuclide time-activity curve with high temporal resolution. The control group consisted of 26 patients referred for ventricular function assessment with radionuclide angiography before cardiotoxic cancer treatment. RESULTS: When the duration of systole was expressed as the product of systolic time and heart rate, DCM patients exhibited a significant increase in left ventricular systolic time at rest (23.9 vs. 21.5 s/min; p = 0.006) and during peak exercise (29.2 vs. 26.7 s/min; p = 0.01). The prolongation of left ventricular systole at peak exercise was evident, although the peak heart rate was significantly lower in the patient group than in the control group (118 vs. 127/min; p = 0.04). In DCM patients the diastolic time loss per beat was further quantified using a regression equation obtained from the healthy control group. A significant shortening of left ventricular diastolic time was confirmed during peak exercise. Furthermore, a progressive loss in diastolic time per beat from rest to peak exercise was noted. CONCLUSION: Cardiac cycle abnormalities of patients with DCM are characterized by a prolongation of left ventricular systole and an abnormal shortening of left ventricular diastole. The systolic-diastolic mismatch is accentuated during exercise and has the potential to impair the cardiac reserve in these patients by restricting ventricular filling and perfusion.

Conversion of recent-onset atrial fibrillation or flutter with ibutilide after amiodarone has failed.

OBJECTIVE: To evaluate whether ibutilide can convert atrial fibrillation or flutter in patients in whom amiodarone has failed. DESIGN AND SETTING: Clinical study in a university hospital intensive care unit (ICU). PATIENTS: Twenty-six patients were studied, in whom atrial fibrillation or flutter persisted for a maximum of 6 h at maximum. Patients were monitored continuously during the arrhythmia. Medical conversion was necessary due to symptomatic or hemodynamic causes. INTERVENTIONS: All patients initially received amiodarone (150 mg i.v.) and after 2 h of persistent arrhythmia ibutilide (1 mg or, without success and body weight > 70 kg, 2 mg i.v.). Before the administration of ibutilide 1 g magnesium was administered, and high normal levels of potassium serum levels were achieved (4.5-5.0 mmol/l). RESULTS. After amiodarone atrial flutter persisted in 73% and atrial fibrillation in 27% of patients. After ibutilide the QT interval was prolonged from 327 +/- 61 to 387 +/- 62 ms. The QTc interval increased from 456 +/-32 to 461 +/- 66 ms. Conversion to normal sinus rhythm was achieved in 22 of 27 of cases. Nonsustained torsade de pointes tachycardia was seen in three patients (11%). No patient showed sustained ventricular tachycardia. Patients with proarrhythmic effects were characterized by a decreased left ventricular function. CONCLUSIONS: In ICU patients ibutilide led to conversion to sinus rhythm in 81.5% of patients in whom amiodarone was unsuccessful. Nonsustained tachycardias were seen in 11%; sustained ventricular tachycardia was not seen. Ibutilide seems to be well suitable for conversion of recent onset atrial fibrillation or flutter and had no severe side effects in this study population.