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Biomedical subjects

O Ickrath

Publications and source records attributed to O Ickrath.

At least 19 recordsLinked to original sources
PubMed1992

Effect of heart rate on transmitral flow velocity profile and Doppler measurements of mitral valve area in patients with mitral stenosis.

To study the effect of heart rate changes on Doppler measurements of mitral valve area atrial pacing was performed in 14 patients with mitral stenosis and sinus rhythm. Continuous wave Doppler and haemodynamic measurements were performed simultaneously at rest and during pacing-induced tachycardia. (1) Mitral valve area was determined using the conventional pressure half time method. (2) Additionally, mitral valve area was calculated with a combined Doppler and thermodilution technique according to the continuity equation. (3) Simultaneous invasive measurements were used for calculation of the mitral valve area according to the Gorlin formula. With increasing heart rate (69 +/- 13-97 +/- 15-114 +/- 13 beats min-1) mitral valve area either determined by the continuity equation (1.0 +/- 0.2-1.0 +/- 0.3-1.1 +/- 0.4 cm2) or the Gorlin formula (1.2 +/- 0.3-1.2 +/- 0.4-1.3 +/- 0.4 cm2) remained constant. Both methods correlated closely not only at rest (r = 0.88, SEE = 0.11 cm2, P less than 0.001), but also during atrial pacing (first level: r = 0.95, SEE = 0.10 cm2, P less than 0.001, second level: r = 0.95, SEE = 0.13 cm2, P less than 0.001). In contrast, mitral valve area calculated according to the pressure half time method increased significantly during atrial pacing (1.0 +/- 0.3-1.8 +/- 0.5-2.0 +/- 0.5 cm2).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Simple computer-assisted diagnosis of acute myocardial infarction in patients with acute thoracic pain.

In order to minimize the initial diagnostic uncertainty in patients suspected of having acute myocardial infarction, we prospectively extracted predictive variables from previous history, ECG, and clinical chemical parameters of 87 patients, who were admitted for acute thoracic pain. The variables thus extracted were: Thoracic pain in previous history, duration of pain, white blood cell count, blood glucose, creatine-kinase, and S-T elevation in the ECG. These parameters were used for formulating a mathematical model based upon univariate and multivariate statistical methods. The sensitivity of the model in the study population was 95% and the specificity 77%. Correct classification was achieved in 89% of cases. In a second phase, the prognostic index was prospectively evaluated in a second set of 122 consecutive patients. In this test population, the sensitivity was 89% and the specificity 86%. 87% of patients were classified correctly.

Adult↗
PubMed1992

[Acute and long-term results of coronary Excimer laser angioplasty].

Laser and catheter technology have been considerably improved within the first 2 years of the clinical use of coronary excimer laser angioplasty. Furthermore, patient selection has changed due to increasing operator experience. We report on the acute- and long-term results achieved in 163 patients in three subgroups with different system parameters and catheter technology. In the initial series 1 (N:60) a prototype catheter with a diameter of 1.4 mm was used. In series 2 and 3, we employed improved transmission devices with 1.3, 1.5 or 1.8 mm. In series 3 the pulsewidth was increased from 60 ns to 115 ns. The target vessel was the LAD in 68%, the LCX in 10%, and the RCA in 21%. According to the AHA/ACC Lesion classification there were 13% type A, 26% type B1, 55% type B2, and 5% type C lesions. Stand-alone laser angioplasty was performed in 23/60 (38%), 24/40 (60%), and 34/64 (53%) in series 1, 2, and 3, respectively. Additional balloon angioplasty was necessary in 32, 11, and 21 interventions. Failure of laser angioplasty occurred in five patients of series 1 and 2, and nine patients of series 3. Frequently observed complications included coronary spasm in 18 to 32%, dissections in 16% to 33%, and vessel closure in 18 to 27%. Myocardial infarction occurred in three patients in the first and one patient of the second and third series. There was one in-hospital death in series 1 and 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Laser↗
PubMed1990

[Myocardial effects of the calcium antagonists nifedipine, nisoldipine and isradipine in coronary heart disease].

Cardiac and peripheral effects of three calcium antagonists of the dihydropyridine group were compared in three groups of ten men each with coronary heart disease (mean age 56 +/- 6 years). Dosages (by 30 minutes intravenous infusions) were: 2 mg nifedipine in group I, 0.5 mg nisoldipine in group II and 0.5 mg isradipine in group III. In this dosage peripheral effects--decrease of peripheral vascular resistance and mean aortic pressure--did not differ significantly between them. As a consequence of different negative chronotropic properties the extent of the observed reflex tachycardia was different: there was no significant heart rate increase after isradipine, an increase by 9.8% (P less than or equal to 0.001) after nifedipine and by 20.4% (P less than or equal to 0.001) after nisoldipine. Left-ventricular pressure-rise velocity as a parameter of myocardial contractility rose by 15.3% in group II (P less than or equal to 0.001) and by 13.5% in group III (p less than or equal to 0.001), but not in group I. These data show, that peripheral equipotent dosages of the three calcium antagonists can have different myocardial effects.

Blood Pressure↗
PubMed1990

Electrophysiologic effects and efficacy of cibenzoline on stimulation-induced atrial fibrillation and flutter and implications for treatment of paroxysmal atrial fibrillation.

The effects of intravenous cibenzoline (1.5 mg/kg) on atrial vulnerability and electrophysiology were assessed in 25 patients with documented paroxysmal atrial fibrillation (AF), in whom sustained (greater than 30 seconds) AF was induced by atrial stimulation with up to 2 extrastimuli and paced rates between 100 and 180 beats/min. In 7 patients AF persisted despite the application of cibenzoline, and in 8 patients the induction of sustained AF was prevented by cibenzoline. Intraatrial conduction time, flutter cycle length and shortest ventricular cycle length during AF were increased by cibenzoline (p less than or equal to 0.01). Sinus cycle length was decreased (p less than or equal to 0.05), whereas sinus node recovery time remained unchanged. The effective refractory period of the right atrium was not significantly affected. Eight patients with frequent episodes of paroxysmal AF received oral cibenzoline for control of paroxysmal AF irrespective of the efficacy of intravenous cibenzoline. Prevention of stimulation-induced AF predicted successful treatment of paroxysmal AF (p = 0.018). Cibenzoline could be effective in the treatment of atrial arrhythmias, and selection of an antiarrhythmic therapy for recurrent AF seems to be useful.

Administration, Oral↗
PubMed1990

Effects of intravenous cibenzoline on ventricular vulnerability and electrophysiology in patients with sustained ventricular tachycardia in comparison to a control group.

The electrophysiologic effects of intravenous (i.v. 1.5 mg/kg) cibenzoline were investigated in 13 patients with organic heart disease and supraventricular arrhythmias (control group) and 13 patients with drug refractory sustained ventricular tachycardia (VT group). In both groups, cibenzoline increased the effective refractory period (ERP) of the right ventricle (p less than or equal to 0.05), QRS duration (p less than or equal to 0.01), and QTc duration (p less than or equal to 0.01). Cycle length of the VT was increased from 311 +/- 73 to 393 +/- 119 ms (p less than or equal to 0.05) as well. The increase in QTc duration was more pronounced (p less than or equal to 0.05) in the VT group as compared with the control group. In four patients in the VT group with the largest increase in QRS-, QTc duration and cycle length of the VT proarrhythmia was noted after i.v. cibenzoline. Cibenzoline plasma levels were not significantly different between the two study groups. In the VT group, induction of VT was prevented in 2 patients, more difficult in 2 patients, easier in 1 patient, and unchanged in 5 patients. Spontaneous occurrence of the VT or induction by atrial stimulation was noted in 4 patients. In the control group, ventricular vulnerability remained unchanged. Cibenzoline may be effective in selected patients with drug refractory VT. In such patients, the increase in QTc duration was more pronounced as compared with a control group.

Anti-Arrhythmia Agents↗
PubMed1990

[Effect of cibenzoline on atrial vulnerability and value of electrophysiological methods in the treatment of paroxysmal atrial fibrillation].

The effects of intravenous cibenzoline (1,5 mg/kg) on atrial vulnerability and electrophysiology were assessed in 25 patients with documented paroxysmal atrial fibrillation, in whom sustained (greater than 30 s) atrial fibrillation/-flutter was induced by programmed atrial stimulation. In seven patients atrial fibrillation persisted despite the application of cibenzoline; in eight patients induction of atrial fibrillation was not prevented. In 10 patients the induction of sustained atrial fibrillation was prevented by cibenzoline. Intraatrial conduction time and shortest ventricular cycle length during atrial fibrillation were increased by cibenzoline (p less than or equal to 0.01). The effective refractory period of the right atrium was not significantly affected. Eight patients with frequent episodes of paroxysmal atrial fibrillation received oral cibenzoline (320 mg/day) for control of paroxysmal atrial fibrillation irrespective of the efficacy of intravenous cibenzoline. Prevention of stimulation-induced atrial fibrillation predicted successful treatment of paroxysmal AF. In conclusion, cibenzoline might be effective in the treatment of atrial tachyarrhythmias. Programmed atrial stimulation seems to be helpful in the prediction of the efficacy of an antiarrhythmic treatment of paroxysmal atrial fibrillation.

Adult↗
PubMed1990

[Effect of acute short-term ischemia during PTCA on the function of the right ventricle].

To determine whether a transient ischemia of the right ventricle leads to right ventricular impairment and whether RV function can also be influenced by septal ischemia caused by an occlusion of the left anterior descending coronary artery (LAD), RV function before and at the end of 60 s of ischemia during PTCA was assessed in 15 patients with single-vessel disease of either the right coronary artery (RCA, n = 10) or the LAD (n = 5). The RV-enddiastolic pressure and the pulmonary capillary wedge pressure (PCW) were recorded continuously. The RV ejection fraction was determined from ventriculograms performed before and during coronary occlusion. An increase of RVEDP from 3.7 +/- 1.2 to 8.3 +/- 1.8 mm Hg (p less than or equal to 0.001) and a decrease of the RV-ejection fraction from 52 +/- 3 to 33 +/- 8% (p less than or equal to 0.001) occurred during RCA occlusion with a predominant ischemia of the RV free wall only, and not during LAD occlusion with left ventricular and septal ischemia. The extent of the RV dysfunction was independent of an additional increase of RV afterload (PCW increase). Comparable to ischemic effects on left ventricular function, an acute right ventricular myocardial ischemia results in a severe RV contractile failure.

Angioplasty, Balloon, Coronary↗
PubMed1990

[Percutaneous coronary Excimer laser angioplasty in patients with coronary heart disease].

To verify the efficacy and safety of percutaneous coronary excimer laser angioplasty in patients with coronary artery disease a prospective study was conducted in 60 patients. The application of laser light was possible in 55 of the 60 patients. A novel 1.4-mm diameter catheter with 20 quartz fibers of 100-microns diameter, each arranged concentrically around a central lumen suitable for an 0.014-inch flexible guide wire was used. The light source was a commercial excimer laser emitting energy at a wavelength of 308 nm, with a pulse duration of 60 ns. The laser was operated at 20 Hz; mean energy transmission was 30 +/- 5 mJ/mm2. In 23 of the 55 patients treated with excimer laser energy the qualitative angiographic results were sufficient. In 32 patients additional balloon angioplasty was necessary, either because of an insufficient result or due to vessel closure after laser ablation. In 47 of the 55 patients control angiography was performed within the 6-month follow-up period. Rate of restenosis was higher in patients treated with laser ablation and subsequent balloon angioplasty (16 of 28) than in patients treated with laser ablation alone (6 of 19). Results of the 6-month observation period suggest that 1) coronary excimer laser angioplasty in combination with subsequent balloon angioplasty results in a considerable increase of the restenosis rate; 2) the exclusive use of laser ablation also results in a restenosis rate comparable to balloon angioplasty alone; and 3) the impact of this new method using improved application systems and higher energy transmission has to be determined in further studies.

Angina Pectoris↗
PubMed1989

Percutaneous coronary excimer laser angioplasty: initial clinical results.

A novel 1.3 mm diameter laser catheter, consisting of 20 concentric 100 microns quartz fibres around a central lumen for a 0.35 mm flexible guide wire, was used to ablate atherosclerotic tissue in thirty patients with coronary artery disease. The laser catheter was coupled to an excimer laser delivering energy at a wavelength of 308 nm and a pulsewidth of 60 ns. The primary success rate was 90% (27 of 30 lesions). The mean (SD) percentage stenosis fell from 85 (15)% to 41 (19)% after laser ablation. In ten patients the lumen diameter after laser angioplasty was considered sufficient, but subsequent balloon angioplasty was carried out for the other twenty patients. Failure to pass the lesion was caused by vessel kinking in two patients and a total occlusion in one patient. No complications directly attributable to laser ablation, such as vessel wall perforation, occurred; one dissection occurred but had no clinical sequelae. There was one early reocclusion and death in a patient with triple vessel disease and unstable angina, probably as a result of plaque rupture after balloon angioplasty. These results are encouraging and justify further clinical investigations.

Angioplasty, Balloon↗
PubMed1989

[Percutaneous transluminal excimer laser coronary angioplasty].

Percutaneous transluminal laser coronary angioplasty (PTLCA) was undertaken in five patients (four men and one woman, aged 44-72 years) with coronary artery stenosis. The vessel diameter was increased in all patients after PTLCA; complete ablation of the atheromatous plaque succeeded in three. In the other two the catheter could not be advanced across the entire stenotic region. After PTLCA the stenoses were 40-50% of normal lumen. Balloon dilatation was additionally done in all five patients. In three this caused dissection of the vessel wall distal to the stenosis and possible intracoronary thrombus formation: this would suggest that balloon dilatation after laser angioplasty is not recommendable. PTLCA widens the spectrum of invasive methods for treating coronary artery stenosis.

Adult↗
PubMed1989

Myocardial properties of the new dihydropyridine calcium antagonist isradipine compared to nifedipine with or without additional beta blockade in coronary artery disease.

Isradipine is a new dihydropyridine calcium antagonist with myocardial effects significantly different from those of nifedipine, as shown by in vitro and animal experimental data. Isradipine selectively inhibits the sinus node but not the atrioventricular conduction and its negative inotropic action is much less if administered in a dose of comparable peripheral effects. To study these effects in man, 40 patients with coronary artery disease were divided into 2 groups receiving either a continuous 30-minute intravenous infusion of 2 mg of nifedipine or 0.5 mg of isradipine, doses that resulted in a comparable afterload reduction (decrease of systemic vascular resistance: nifedipine -22.1%, isradipine -25%, p less than 0.001). Ten patients in each group received an additional intravenous bolus of 5 mg of propranolol at the end of the calcium antagonist administration to antagonize its induced adrenergic reflex mechanisms. The heart rate significantly increased after nifedipine only (+9.2%, p less than 0.001), experienced no change after isradipine and the nifedipine and propranolol combination and decreased after the combination of isradipine and propranolol (-9.6%, p less than 0.001). This resulted in a significant decrease of the rate pressure product with isradipine (-12.5%, p less than 0.001) but not with nifedipine. As a result of the afterload-induced adrenergic reflex mechanisms, the maximal derivative of the left ventricular pressure increased after isradipine administration (+13.5%, p less than 0.001) and was unchanged after nifedipine, which demonstrates the significantly less negative inotropic properties of isradipine as compared with nifedipine.

Adrenergic beta-Antagonists↗
PubMed1989

Comparison of the effects of intravenous and oral betaxolol on antegrade and retrograde conduction in patients with atrioventricular nodal reentrant and atrioventricular reentrant tachycardia.

The electrophysiologic effects of intravenous (0.15 mg kg-1) and oral (20 mg day-1) betaxolol have been investigated in 11 patients with atrioventricular (A-V) nodal reentrant tachycardia and eight patients with orthodromic A-V reentrant tachycardia. Betaxolol significantly (P greater than 0.01) prolonged sinus cycle length, sinus node recovery time, intranodal conduction time, and the antegrade functional refractory period of the A-V node. When the effective refractory period of the A-V node could be determined it was increased by betaxolol, whereas no significant electrophysiologic effects were observed in the atrium, the ventricle or the accessory pathway. Intravenous betaxolol prevented tachycardia in 8 out of 11 patients with A-V nodal reentrant tachycardia, whereas oral betaxolol was effective in 10 patients, primarily by acting on the antegrade limb in two patients and on the retrograde limb in eight patients. In those with A-V reentrant tachycardia, intravenous betaxolol did not prevent tachycardia in any patient, while it was effective after oral treatment in two patients. When the tachycardia remained inducible, cycle length of the tachycardia increased in all patients, due to prolongation of the antegrade and retrograde conduction time in patients with A-V nodal reentrant tachycardia, and due to an increase in the antegrade conduction time, i.e. the A-V node, in the patients with A-V reentrant tachycardia. In conclusion, betaxolol proved to be effective in the treatment of supraventricular tachycardia; for chronic treatment, a single oral dose (20 mg) seems to suffice.

Administration, Oral↗
PubMed1989

[Success and complication rates of coronary angioplasty in the unstable angina pectoris stage after myocardial infarct--a comparison with percutaneous transluminal coronary angioplasty in the acute infarct stage and unstable angina pectoris without preceding myocardial infarct].

To evaluate whether there is a difference in terms of the success and complication rates of PTCA in patients (pts) with unstable angina pectoris (UAP) after myocardial infarction (group I) and patients with myocardial infarction (group II), as well as in patients with UAP without preceding myocardial infarction (group III), we analyzed the data of 188 patients retrospectively. Acute PTCA was performed in 42 patients of group I, 55 patients of group II, and 91 patients of group III. The primary success rate was comparable in all three groups (group I: 74%; group II: 76%; group III: 77%). The incidence of acute ACVB operation was comparable in group I (5 pts: 9%) and group III (10 pts: 11%). One patient was operated during an acute myocardial infarction. Five patients of group I (9%) and seven patients of group III (8%) developed a myocardial infarction. Three patients of group I (7%) and three patients of group II (5%) died during hospitalization. PTCA performed during acute myocardial ischemia has the highest complication rate in patients with UAP after myocardial infarction and is considerably higher than in patients with UAP without preceding infarction.

Angina Pectoris↗
PubMed1989

[The acute hemodynamic effects of the new vasodilating beta blocker carvedilol in comparison with combined administration of nifedipine and propranolol in patients with coronary heart disease].

The acute hemodynamic effects of carvedilol, a new vasodilating betablocker, were assessed in comparison to the response to nifedipine or a combination of nifedipine and propranolol in patients with coronary artery disease. Either 5 mg carvedilol, 2 mg nifedipine or 2 mg nifedipine + 5 mg propranolol (N + P) were administered intravenously in a not randomized study within 30 min to 10 patients for each drug. Carvedilol reduced (comparable to the effect of N + P) the left ventricular afterload with a decrease of AOPm of 12.6%, p less than 0.001 (N + P -11.8%, p less than 0.001) and systemic vascular resistance of 9.1%, p less than 0.02 (N + P -10.0%, p less than 0.01) and no change of cardiac index. Single treatment with nifedipine leads to a reflex increase of heart rate which could not be observed after carvedilol or N + P as a result of the betablocking properties of carvedilol and propranolol. Therefore, the rate-pressure-product at rest was unchanged after nifedipine but decreased significantly after carvedilol (-10.9%, p less than 0.01) and N + P (-12.4%, p less than 0.01). Negative inotropic effects were significantly lower after carvedilol, with a 6.3% (p less than 0.05) decrease of LV dP/dtmax, compared to N + P (-12.0%, p less than 0.01). Since preload, afterload, and heart rate changes were equal in both groups negative inotropic effects can be compared on the base of dP/dtmax changes. The acute hemodynamic effects (vasodilation without reflex tachycardia, negative inotropic effects) of the new vasodilating betablocker carvedilol are comparable to a combined treatment with nifedipine and propranolol in patients with coronary artery disease and well preserved left ventricular global function.

Carbazoles↗
PubMed1989

[Electrophysiologic properties of cibenzoline in Wolff-Parkinson-White syndrome and atrioventricular nodal reentry tachycardia].

The electrophysiologic effects of the new class-1 antiarrhythmic drug cibenzoline (1.5 mg/kg within 10 min, followed by an infusion of 0.5 mg for 30 min) were investigated in six patients with atrioventricular (av) nodal reentrant tachycardia and nine patients with atrioventricular tachycardia. Sinus cycle length, sinus node recovery time, effective refractory period (ERP) of the atrium and the ventricle as well as the ERP of the av node were not significantly affected by cibenzoline. Retrograde conduction via the av node was prevented by cibenzoline in 6/15 patients, retrograde ERP was increased in 4/15 patients and in 5/15 patients determination of the retrograde ERP of the AV node was impossible. Intranodal conduction time (AH-interval) and infranodal conduction time (HV-interval) was increased from 96 +/- 27 ms to 117 +/- 40 ms (p less than 0.01) and 36 +/- 12 ms to 62 +/- 12 ms (p less than 0.01), respectively. In four patients with antegrade conduction along the accessory pathway no antegrade conduction was seen after the application of cibenzoline. Retrograde ERP of the accessory pathway was increased in two patients, it was unchanged in three patients, and no retrograde conduction along the accessory pathway was seen in four patients. AV nodal reentrant tachycardia was not inducible, after cibenzoline in 4/6 patients and in 5/9 patients with AV reentrant tachycardia. If tachycardia remained inducible, an increase in tachycardia cycle length from 333 +/- 46 ms to 402 +/- 24 ms was observed (p less than 0.01). In conclusion the electrophysiologic effects of cibenzoline make it a suitable drug for the treatment of av nodal reentrant tachycardia and atrioventricular tachycardia.

Adult↗
PubMed1989

[Determination of the right ventricular ejection fraction from the exponential decrease in the thermodilution curve--a comparison with biplanar cineventriculography].

Using the exponential downslope of the thermodilution curve right ventricular ejection fraction and volumes can be calculated. To evaluate the accuracy of this method for clinical application thermodilution measurements were compared to the results of biplane cineventriculography in 40 patients. Mean right ventricular ejection fraction was 52 +/- 9% determined by thermodilution (Th), and 53 +/- 8% determined by angiography (A). Mean enddiastolic volume was 189 +/- 74 ml (Th) and 162 +/- 42 ml (A) and mean endsystolic volume 92 +/- 42 ml (Th) and 75 +/- 20 ml (A). Ejection fraction of thermodilution measurements correlated with the results of angiography (r = 0.59; SEE = 7%; % SEE = 13 rel. %; p less than 0.001). The correlation for endsystolic volume was: r = 0.50; SEE = 36 ml; % SEE = 48%; p less than 0.001, and for enddiastolic volume: r = 0.36; SEE = 70 ml; % SEE = 43%; p less than 0.05. The differences in ejection fraction calculated by the two different methods were especially high (up to 25%) in patients (n = 10) with low (less than 110 ml) or high (greater than or equal to 200 ml) enddiastolic volume. For the other 30 patients the correlation for right ventricular ejection fraction was: r = 0.82; SEE = 5%; % SEE = 9 rel. %; p less than 0.001. Thus, the thermodilution method allows an approximative assessment of right ventricular ejection fraction only in patients with a normal right ventricle. Since right ventricular ejection fraction cannot be determined with sufficient accuracy in patients with right ventricular dilatation, the clinical application of this method is limited.

Cardiac Output↗