Biomedical subjects

T Hilbel

Publications and source records attributed to T Hilbel.

22 records · Page 2Linked to original sources

PubMed1992

Sotalol exhibits reverse use-dependent action on monophasic action potentials in normal but not in infarcted canine ventricular myocardium.

In 12 anesthetized mongrel dogs (30 mg/kg pentobarbital), a thoracotomy was performed, and the left anterior descending coronary artery was ligated proximally. Eight to 12 days later, monophasic action potentials were recorded endocardially from the apex of the noninfarcted right ventricle and infarcted areas of the left ventricle, and the effects of 1.5 mg/kg intravenous sotalol were evaluated. Monophasic action potentials from the infarcted zone of the left ventricle were obtained from areas where fractionated bipolar electrograms could be recorded; this was histologically confirmed. After sotalol, in sinus rhythm, the monophasic action potential duration at 90% repolarization of the infarcted zone increased from 186 +/- 31 to 226 +/- 45 ms (+ 22%, p less than 0.05), and monophasic action potential duration of the noninfarcted zone increased from 184 +/- 31 to 225 +/- 47 ms (+ 22%, p less than 0.05). Programmed ventricular stimulation was performed with single extrastimuli at a basic drive cycle length of 300 ms. With long coupling intervals (290 ms), monophasic action potential duration of the infarcted zone increased from 165 +/- 23 to 183 +/- 25 ms (+ 11%, p less than 0.05) after sotalol; and monophasic action potential duration of the noninfarcted zone increased from 159 +/- 20 to 180 +/- 25 ms (+ 13%, p less than 0.05). With short coupling intervals (200 ms), the monophasic action potential duration of the noninfarcted zone increased from 157 +/- 19 to 173 +/- 18 ms (+ 10%, p less than 0.05), and monophasic action potential duration of the noninfarcted zone increased from 150 +/- 18 to 157 +/- 18 ms (+ 5%, NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗

PubMed1992

Electrophysiologic and antiarrhythmic effects of D-sotalol.

There is extensive experimental and clinical experience concerning the antiarrhythmic potency of DL-sotalol, a beta-adrenergic antagonist that lengthens the cardiac action potential duration. More recently, its dextrorotatory isomer, D-sotalol, has been evaluated in experimental studies and preliminary clinical trials. Whereas the isomer is almost free of beta-blocking activity, both experimental and clinical data demonstrate that potent class III activity of D-sotalol. Further investigations, particularly in patients with life-threatening arrhythmias, are needed to delineate the clinical usefulness of this compound.

Action Potentials↗

PubMed1991

Characteristics of endocardial monophasic action potentials recorded from areas with fractionated bipolar electrograms in infarcted canine ventricular myocardium.

STUDY OBJECTIVE: The aim was to characterise monophasic action potentials recorded from subacutely infarcted myocardial regions, where fractionated bipolar electrograms could be obtained. DESIGN: Dogs underwent ligation of the left anterior descending coronary artery. Before and 8-12 d after ligation, monophasic action potentials and local electrograms were recorded endocardially from the apex of the left ventricle. EXPERIMENTAL MATERIAL: 15 anaesthetised mongrel dogs (30 mg pentobarbitone.kg-1) were used. MEASUREMENTS AND MAIN RESULTS: Multiphasic fractionated bipolar electrograms could be recorded from infarcted sites of the left ventricle with a mean duration of 69(SD 10) ms and a mean amplitude of 3.7(1.6) mV, compared to control values of 42(7) ms (p less than 0.05) and 9.4(2.2) mV (p less than 0.05), respectively. Endocardial monophasic action potentials recorded from these areas were similar to action potentials obtained from non-infarcted sites before coronary ligation. The fractionated extracellular potentials were superimposed on the monophasic action potential upstroke. MAP90 was 189(31) ms, MAP30 138(12) ms, versus control values of 182(27) ms and 139(10) ms (NS). Monophasic action potential amplitude was significantly reduced at infarcted sites compared to control, at 26(7) mV v 38(6) mV. Histological specimens were taken to confirm that measurements were obtained from infarcted tissue. CONCLUSIONS: It is possible to record monophasic action potential in subacutely infarcted canine ventricular myocardium; this technique might help in further studies to characterise electrophysiological mechanisms of ventricular arrhythmias in chronic myocardial infarction in man.

Action Potentials↗

PubMed1991

[Combined anti-bradycardia/anti-tachycardia pacemaker-cardioverter-defibrillator systems in patients with recurrent ventricular tachyarrhythmias].

In 41 patients with recurrent sustained ventricular tachycardia and/or ventricular fibrillation an integrated pacemaker-defibrillator-system (PCD, Medtronic, model 7216 A or 7217 B) was implanted. In 21 out of 24 (88%) patients a new transvenous implantation technique in combination with a subcutaneous patch electrode was used. The implanted devices comprise antibradycardiac pacemaker functions, two different forms of antitachycardiac pacemaker functions (ramp and burst pacing), and internal cardioversion or defibrillation capabilities. During a mean follow-up of 8 months 147 episodes of ventricular tachycardia were detected, 131 of them were terminated successfully by antitachycardiac pacing; in 13 episodes internal cardioversion was applied to revert ventricular tachycardia. Twenty-seven episodes of ventricular fibrillation or rapid ventricular tachycardia (greater than 200/min) were detected and successfully terminated by internal defibrillation. In six patients with intermittent rapid atrial fibrillation, change of antiarrhythmic therapy was required to avoid activation of the device. The new integrated pacemaker-defibrillator systems improve therapy in patients with life-threatening tachyarrhythmias by reducing the number of internal cardioversions/defibrillations; the non-thoracotomy approach reduces the post operative risk.

Adult↗