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Biomedical subjects

H Katus

Publications and source records attributed to H Katus.

30 records · Page 2Linked to original sources
PubMed1982

Intracoronary thrombolysis in acute myocardial infarction: duration of ischemia as a major determinant of late results after recanalization.

To define the effect of duration of myocardial ischemia on the late results after successful thrombolysis in patients with acute transmural myocardial infarction, data on 39 patients treated with intracoronary infusion of streptokinase were analyzed. Patients with successful recanalization of infarct vessel and a time lag between onset of symptoms and reperfusion less than 4 hours were assembled in group A1 (n = 15), and patients with successful recanalization but a time lag of more than 4 hours (n = 17) in group A2. Group B consisted of 7 patients with unsuccessful thrombolysis. Coronary anatomy, left ventricular volume, ejection fraction, and regional ejection fraction of infarct area were determined before and 4 weeks after thrombolysis with cineangiography. Serum creatine kinase activity was serially measured. Before intervention, the groups were comparable with regard to age, Killip class, localization of infarction, incidence of previous infarction, Gensini score of coronary anatomy, left ventricular volume, ejection fraction, regional ejection fraction of infarct area, and serum creatine kinase activity. Four weeks after the intervention, patients in group A1 had a higher ejection fraction (59%) and regional ejection fraction of infarct area (39%) than patients in group A2 (ejection fraction: 49%, p less than 0.05; regional ejection fraction: 26%, p less than 0.05) and group B (ejection fraction: 44%, p less than 0.05; regional ejection fraction: 25%, p = 0.05). Peak serum creatine kinase activity measured during the acute illness was lower in group A1 (764 U/liter) than in group A2 (1,580 U/liter, p less than 0.05) and group B (2,106 U/liter, p less than 0.05). Thus, contraction of infarct area was improved and enzymatic estimate of infarct size was reduced after early as compared with late reperfusion in patients with acute myocardial infarction.

Aged↗
PubMed1977

Ventricular arrhythmias in cardiac anaphylaxis.

Arrhythmogenic effects of anaphylaxis and histamine were studied in guinea pigs by measuring changes of transmembrane potentials from isolated papillary muscles. Antigenic challenge of preparations obtained from passively sensitized animals induced ventricular automaticity in 1/3 of the experiments. The arrhythmogenic effects of cardiac anaphylaxis could be reproduced by exogenous histamine. Abnormal automaticity was associated with a stable diastolic membrane potential in most of the ventricular fibres and only occasionally ectopic pacemaker potentials were observed in fibres near the ventricular septum. The effective refractory period, maximum rate of depolarization of the action potential and electrical threshold were not significantly changed in ventricular anaphylaxis but in the presence of histamine the refractory time was shortened. Ventricular arrhythmias induced by histamine were increased at high extracellular Ca2+ concentrations and inhibited by Mn2+ and D 600 but were only moderately antagonized by tetrodotoxin. Pretreatment with reserpine had no effect on the abnormal automaticity. Spontaneous ventricular activity caused by histamine was markedly inhibited by the histamine H2-receptor antagonist burimamide and also by the antiarrhythmic drug, prajmalium bitartrate. The H1-receptor antagonist brompheniramine, hydrocortisone and propranolol had little or no antiarrhythmic effect.

Action Potentials↗
PubMed1976

Action of anaphylaxis and histamine on isolated mammalian ventricles: contractile hyperactivation and changes of membrane potentials.

The effects of anaphylaxis and histamine on the action potential and the isometric contraction of isolated guinea-pig papillary muscles have been investigated. The anaphylactic reaction was found to affect directly ventricular muscle fibers. The anaphylactic alterations of membrane and contraction parameters were very similar to effects of histamine and were not affected by pretreatment with reserpine. Isometric contraction developed typical features of contractile hyperactivation, characterized by a marked increase of peak force associated with shortening of time to peak of contraction and the appearance of oscillatory contractions and aftercontractions. Mechanical alternans and electrical alternans were also observed. Oscillatory contractions occurring during membrane depolarization were increased with prolongation of the action potential duration. After contractions developed after complete repolarization of the membrane and increased at higher stimulation rates. The anaphylactic reaction and histamine caused shortening of the action potential. Resting potential, overshoot and maximum rate of rise of action potential were not significantly changed. A common mechanism of contractile hyperactivation based on a multicompartment model of the intracellular Ca movements in discussed.

Anaphylaxis↗
PubMedDate not supplied

Intropic and electrophysiological action of humoral factors released in cardiogenic shock after acute myocardial infarction.

The inotropic and electrophysiological effects of plasma obtained from patients and experimental dogs during cardiogenic shock following acute myocardial infarction were studied. Changes in the isometric contraction and the intracellular action potential were determined in isolated papillary muscles of rabbits. Control plasma collected from normal subjects produced no significant changes in the contraction or the electrical parameters. Plasma from shock patients decreased peak force by 42% and the maximum rate of force development by 38% in comparison to control values; the time to peak of contraction, the relaxation time and the action potential parameters were not significantly altered. Corresponding results were obtained with plasma from dogs before and during experimental cardiogenic shock. Biochemical determinations failed to identify a single specific "myocardial depressant factor" in the plasma of patients and dogs with cardiogenic shock. The results suggest that (1) various humoral factors released during cardiogenic shock may depress the contractile function of cardiac muscle and (2) that the observed negative intropic effect is not due to electrical changes in the cell membrane.

Action Potentials↗
PubMedDate not supplied

Comparison between the effect of postextrasystolic potentiation and the effect of nitrates on left ventricular function for the differentiation between reversible and irreversible left ventricular asynergy.

In patients with coronary heart disease (CHD) it is important to differentiate between reversible and irreversible left ventricular (LV) asynergy. Therefore global and regional LV function was investigated in the postextrasystolic beat (PES) and after isosorbide dinitrate (ISDN). In 24 patients LV angiograms were performed before and after ISDN. The ejection fraction (EF) was determined in a sinus beat and in PES. Regional LV performance was measured by the shortening of the length axis and six short hemiaxes. In 12 patients with normal LV function at rest EF increased from .72 +/- .04 (+/- 1 SD) to .77 +/- .04 (P less than 0.05) after ISDN and rose further to .81 +/- .02 in the PES (P less than 0.05). In 12 patients with CHD and LV asynergy EF increased from .43 +/- .12 to .47 +/- .13 after ISDN (P less than 0.05) and rose further to .57 +/- .13 in the PES (P less than 0.02). After ISDN 23/39 asynergic axes improved, 15/39 axes did not change, 1/39 axis decreased its shortening by 12%. In the PES 26/39 axes improved, 6/39 axes did not change; 7/39 axes showed less shortening, presumably due to a systolic shift of blood into dyskinetic regions with LV scar. It is concluded: The PES affects viable myocardium more than does ISDN; the PES is easier to perform and permits a more precise distinction between reversible and irreversible LV dyskinesis.

Coronary Disease↗