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Biomedical subjects

M Oeff

Publications and source records attributed to M Oeff.

35 records · Page 2Linked to original sources
PubMed1991

Phase image triangulation of accessory pathways in patients undergoing catheter ablation of posteroseptal pathways.

The outcome of posteroseptal accessory pathway ablation by direct current (DC) shocks delivered just outside the os of the coronary sinus was studied in 21 patients. Electrocardiographic and electrophysiological parameters as well as phase image patterns of equilibrium multiple-gated blood-pool scintigrams were studied to determine their usefulness in predicting the success of ablation. A second free-wall pathway was documented by electrophysiological or surgical findings in six patients, and the value of phase images in detecting this second pathway was studied as well. Ablation was successful in 57%. The cumulative mean energy of DC shocks amounted to 524 +/- 170 joules and was not predictive of ablation outcome, neither was the mean ventriculoatrial (VA) conduction time. The predictive value of the 12-lead maximally preexcited electrocardiogram was poor in the 15 patients with a single posteroseptal bypass tract. A new method to triangulate the site of the earliest phase angle on the atrioventricular (AV) valve plane successfully localized the bypass pathway in 14 of those patients. No specific phase pattern predicted successful ablation except for a symmetrical, concentric peripheral phase progression found to be predictive of ablation success in the four patients who showed this pattern. Phase analysis was able to localize the second, nonposteroseptal pathway in four of six patients. This study showed that a concentric peripheral phase progression in the gated blood-pool scintigrams is predictive for ablation success in patients with posteroseptal pathways. A free-wall localization of the earliest phase angle is suggestive of a second bypass tract in this area.

Adolescent↗
PubMed1990

Inefficacy and proarrhythmic effects of flecainide and encainide for sustained ventricular tachycardia and ventricular fibrillation.

OBJECTIVE: To assess the efficacy of encainide and flecainide in treating patients with sustained ventricular arrhythmias. DESIGN: Patients were treated with encainide or flecainide. Efficacy was assessed by comparing the results of programmed ventricular stimulation while patients received therapy with the results while they were drug free. SETTING: The electrophysiology laboratory of the University of California at San Francisco. PATIENTS: Forty-nine patients with spontaneous or inducible sustained ventricular tachycardia or ventricular fibrillation for whom treatment with at least one class IA antiarrhythmic agent had failed. INTERVENTIONS: Patients were treated with encainide, 35 to 50 mg three or four times daily, or flecainide, 100 to 200 mg twice daily. RESULTS: Arrhythmia worsened early in 5 of 16 patients receiving encainide and 3 of 33 patients receiving flecainide. Patients with poor left ventricular function were more likely to exhibit proarrhythmia (P = 0.02). Nine of eleven patients receiving encainide and 23 of 28 patients receiving flecainide who had repeat programmed ventricular stimulation while receiving drug therapy still had inducible, poorly tolerated ventricular tachycardia. CONCLUSION: Encainide and flecainide have a low efficacy rate and a high incidence of worsening of arrhythmia in patients with sustained ventricular arrhythmias, particularly when this condition is associated with poor left ventricular function.

Adult↗
PubMed1990

Effects of multipolar electrode radiofrequency energy delivery on ventricular endocardium.

This study examined the effects of radiofrequency energy applied in a bipolar fashion with single as compared with multiple sequential applications at the canine endocardium. In this closed-chest model, radiofrequency energy (750 kHz) was delivered between two adjacent poles of an electrode catheter. Single applications were performed at distinct sites in the left (n = 30) and right ventricles (n = 29) of 13 normal dogs. A multiple sequential technique, which enlarges the ablated endocardial surface, was applied in the left (n = 13) and right ventricles (n = 4) of seven normal dogs and six dogs with remote myocardial infarction. Single applications (199 +/- 200 joules) resulted in lesions with a volume of 0.12 +/- 0.06 cm3 (range 0.03 to 0.31 cm3) and an endocardial surface area of 0.29 +/- 0.15 cm2 (range 0.06 to 0.63 cm2). Changes at the catheter/tissue interface led to a rise in impedance, restricting further enlargement of the necrosis. Sequential delivery of radiofrequency energy between poles 1 and 2, 2 and 3, and 3 and 4 of a quadripolar electrode catheter repeated 9 to 11 times in slightly different positions allowed a cumulative energy of 6571 +/- 3857 joules to be applied to the endocardium, resulting in a lesion volume of 0.84 +/- 0.38 cm3, with an endocardial lesion surface area of 3.7 +/- 1.2 cm2 (range 2.9 to 5.1 cm2). Histologically, all radiofrequency lesions were restricted to the endocardium/subendocardium with a small border zone of injury. Aggressive stimulation techniques did not induce ventricular tachycardia in any of the dogs before and 19 +/- 11.4 days after multiple sequential ablations.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Catheter ablation of canine myocardium with radiofrequency energy.

High energy direct-current shocks delivered via an electrode catheter have been used to ablate the atrioventricular junction since 1981. This technique has also been adapted for ablation of other cardiac tissues including the atrium, posterior interatrial septum and ventricular myocardium. The limitations of this technique include inadequate control of the energy source, poor understanding of the mechanisms of myocardial injury, and untoward complications possibly related to barotraumatic injury. Radiofrequency energy has been shown to create ablative injury when delivered to the myocardium via standard electrode catheters. This report will review our experience with radiofrequency catheter ablation of the canine myocardium with specific emphasis on the biophysical aspects of lesion formation.

Animals↗
PubMed1986

Methods for non-invasive detection of ventricular late potentials--a comparative multicenter study.

To evaluate the methodological problems of the non-invasive registration of late potentials the results obtained with four different averaging devices in the same 109 patients were compared. The high-resolution ECG was obtained from the body surface, high-gain amplified and filtered. With the averaging technique, the improved signal-to-noise ratio was able to detect low-amplitude cardiac activity. The incidence of late potentials detected with the four averaging systems, whose characteristics are described, ranged between 12% and 21%. Corresponding positive results were obtained in 5.5%, corresponding negative results in 68.8%. The reasons for differing results were mainly due to differences in visual or automatic interpretation of the registered fractionated electrical cardiac activity. Additionally, the determination of the end of QRS using the QRS width, obtained from reference leads, may influence the specificity of the methods.

Cardiac Complexes, Premature↗
PubMed1986

[Noninvasive registration of spontaneous ventricular potentials in patients with healthy hearts and in patients with intraventricular impulsive conduction disorders. Method and results of the signal averaging technic].

For registration of delayed depolarizations 50 healthy persons (age: 49.4 +/- 6.2 years) and 43 patients with bundle-branch block (age: 65.1 +/- 11.8 years; 23 of them with right and 20 with left bundle-branch block) underwent high-resolution electrocardiography at the body surface using signal-averaging technique. The findings were compared with results obtained in the 24-hour long-term ECG. In 2 normal persons (4%), delayed depolarizations were recorded whose configuration, however, differed from that of pathological findings in patients with coronary heart disease. 2 other subjects evidenced repetitive ventricular arrhythmias. Detection of delayed depolarizations in patients with coronary heart disease is indicative of an increased risk of malignant or even fatal arrhythmias. The low prevalence in healthy subjects underlines the specificity of this finding and represents the prerequisite for identifying patients with an increased risk. Delayed depolarizations were found also in 3 patients with right and 4 patients with left bundle-branch block (16.3% in all). 8 patients had repetitive ventricular arrhythmias, and one of them with a left bundle-branch block also revealed delayed depolarizations. Thus delayed depolarizations can be registered in some patients with intraventricular conduction defects. The incidence rate corresponds to that found in patients with coronary heart disease, so that detection of delayed depolarizations in this patient group is not helpful in the assessment of prognosis.

Adult↗
PubMed1984

[Effects of diltiazem on rest and stress hemodynamics in coronary disease].

The acute hemodynamic effects of the Ca-antagonist Diltiazem were measured in the course of diagnostic cardiac catheter examinations in 10 patients with coronary heart disease. After initial step-wise ergometric stress, Diltiazem (D) was applied intravenously for 5 min at a dose of 0.3 mg/kg. The effects on right and left ventricular performance as well as on arterial pressure and heart rate were registered 1, 3, 5, 10 and 15 min after termination of the infusion. Then, a second period of ergometric exertion under identical stress conditions was performed. The results under resting conditions show that D effects a significant increase in left ventricular filling pressure (p greater than 0.005), which, however, only lasts a few minutes. After D, the systolic and mean arterial pressure decreases significantly (p greater than 0.001); there is no reflex-induced increase in the heart rate, which on the contrary is significantly lower (p greater than 0.005) 15 min after termination of the infusion than the initial value. The stroke volume index increases from 40 to maximally 48 ml/m2 after D. Comparison of the hemodynamic parameters under ergometric stress before and 20 min after D shows that, on termination of stress, the filling pressure of the left ventricle is reduced. This behavior can largely be attributed to the reduction of the systolic pressure after D (maximal value before D 181, after D 167 mm Hg). Also, the stress-induced increase in the heart rate takes a flatter course after D than before it. The results obtained thus provide evidence that, at a dosage of 0.3 mg/kg, D has no significant negative inotropic effect and probably leads to a decrease of the myocardial oxygen consumption reducing the systolic pressure and, to a lesser degree, heart rate.

Adult↗
PubMed1984

[Changes in contractility parameters, coronary flow and myocardial oxygen consumption following intravenous diltiazem in patients with coronary heart disease].

In 11 patients (9 men, 2 women) with angiographically confirmed coronary heart disease, hemodynamics, myocardial blood flow, oxygen consumption and lactate extraction were measured at rest before and after administration of 0.3 mg diltiazem per kg body weight. There was a prompt and sustained drop in mean systolic arterial pressure from 141 mm Hg to 127 mm Hg along with a reduction in total peripheral resistance. The filling pressure of the left ventricle remained constant following a post-injection rise lasting up to 5 minutes. A marked sustained drop in heart rate from 82/min to 73/min was registered. Concomitantly, stroke volume index rose from 39 to 49 ml/m2. Due to the decrease in load and frequency, contractility parameters dP/dt and dP/dt/P dropped slightly. Myocardial blood flow did not change. On the other hand, a decrease in the difference between arterial and coronary venous oxygen content indicated a coronary dilatory effect. Fifteen minutes after injection, myocardial oxygen consumption had dropped from 11.6 to 10 ml O2/min and 100 g of tissue. There was no substantial change in lactate extraction. Through a drop in peripheral arterial resistance and heart rate, diltiazem leads to a measurable decrease in myocardial oxygen consumption while the patient is still at rest. At the same time, there are indications of a coronary dilatory effect.

Adult↗
PubMed1982

[Systemic thrombolysis with short-term streptokinase infusion in acute myocardial infarct].

Within 6 hours after the onset of acute myocardial infarction, 93 patients received a brief high-dose intravenous infusion of streptokinase, 49 patients received 500,000 IU within 30 min and 44 patients received 1,500,000 IU within 60 min. 26 patients had angiography in the acute phase, after 24 hours, and in the 4th week; 52 patients had angiography in the 4th week only; and 15 had no angiography. 7 patients died in hospital and 6 suffered a nonfatal reinfarction. There were no complications with bleeding. In 52% of cases, reopening of an occluded infarct vessel was achieved within 1 hour of the beginning of treatment. During the 4th week after infarction a patent infarct vessel was found in 84%, and 58% had a residual stenosis less than 70%. In contrast, in a control group that received no streptokinase treatment, 25% had a patent infarct vessel and 4% had a residual stenosis less than 70%. Indicative for salvage of ischemic myocardium are a significant improvement in local contraction disorders between the acute phase and the 4th week and a significant correlation between infarct size in the 4th week and beginning of treatment after onset of symptoms. 1. It may be concluded that: brief intravenous infusion of streptokinase results in restoration of blood flow in an infarcted coronary artery in a high percentage of cases; the shorter thrombus-lysis time with intracoronary streptokinase infusion could be made up for by the earlier initiation of intravenous streptokinase treatment; and a conclusive randomized trial is needed to ascertain the true impact of a brief high-dose intravenous infusion of streptokinase on mortality and morbidity following acute myocardial infarction.

Adult↗
PubMed1981

[Risks of treatment with beta-blocking agents in acute myocardial infarction (author's transl)].

Haemodynamic investigations were performed in 40 patients with acute myocardial infarction before and after intravenous application of 6 mg propranolol. Cardiac index was significantly decreased caused by reduction of cardiac frequency and stroke volume. Pulmonary capillary pressure increased significantly. As a consequence pulmonary and peripheral vascular resistance increased. Arterial blood pressure remained largely unaffected. Propranolol showed a haemodynamically beneficial decrease of left ventricular stroke work without signs of negative cardiodepression at a cardiac index of more than 3.0 l/min . m2. At a cardiac index of less than 3.0 l/min . m2 a haemodynamically detrimental lowering of cardiac index to ranges of insufficiency of 2.0 l/min . m2 on average occurred. Thus cardiac index is an important factor for the decision of use of beta-blocking agents in acute myocardial infarction. Indiscriminate use of beta-blocking substances should not be accepted.

Adult↗
PubMed1981

[The treatment of acute myocardial infarctions with beta-receptor-blockers. II. Hemodynamic effects of propranolol with and without combination therapy with nitroglycerin (author's transl)].

In 20 infarct patients, whose age varies from 43 to 78 years (m 59.6), continuous hemodynamic measurements were made to determine the cardiovascular effects of propranolol without and during a simultaneous infusion treatment with nitroglycerin. In cases of compensated ventricular function and pulmonary wedged pressures of 15 mm Hg or less (N = 10), a mean intravenous propranolol dose of 6.1 +/- 1.3 mg led to a significant reduction of the LVSWI and a simultaneous increase of the PCP by 31% of the control value (P less than or equal to 0.005). A simultaneously performed infusion treatment with nitroglycerin at a mean dose of 3.0 +/- 1.6 mg/h resulted in totally cutting off the propranolol-induced PCP increase, whereas a decrease of the heart rate and the LVSWI due to a beta-receptor-blockade remained completely unchanged. In the case of pre-existing congestion insufficiency of the left ventricle (N = 10) and of a pulmonary wedged pressure of above 15 mm Hg, the administration of a mean dose of propranolol of 5.8 +/- 1.1 mg for protection of the myocardium resulted in a partly disquieting decrease of the volume of cardiac output (P less than or equal to 0.005) which was 28% of the control value for the CI an 12% for the SVI. Correspondingly the left ventricular stroke work decreased to 18%. Nitroglycerin has a reducing influence on these changes, but not down to the initial level. In cases of sufficient ventricular function, propranolol has a favorable influence on the myocardial O2-metabolism via its depressor effect on heart rate and contractility. By means of nitroglycerin, an increase of the pulmonary wedged pressure occurring under this condition can be inhibited. However, in the case of a pre-existing congestion insufficiency, propranolol can lead to a partly disquieting depression of the circulation, which, apart from the hemodynamic risks, makes a rather unfavorable influence on the myocardial O2-metabolism seem likely.

Adult↗
PubMed1981

[Treatment of acute myocardial infarction with betareceptor blocking agents. I. Hemodynamic effects of Propranolol in combination with digitalis (author's transl)].

In the acute stage of transmural myocardial infarction, 22 patients ranging in age from 34 to 76 (mean 61.6) were given propranolol- because of its alleged myocardium-protecting properties - intravenously at a dosage of 0.03 to 0.1 mg/kg body weight under conditions of continuous hemodynamic control. Subsequently, the influence of digoxin, administered i. v. at a dosage of 0.01 my/kg body weight, on the negative-inotropic propranolol effects was examined. A hemodynamic comparison was made of the effects of propranolol before and after digitalis administration. In patients with compensated cardiac function (group 1, 16 patients), the propranolol-induced drop in the left ventricular stroke-work-index and rise in the left-ventricular filling pressure was completely compensated again by digitalis. The frequency-decreasing propranolol effect was nor influenced by digitalis. In patients with cardiac decompensation (group 2, 6 patients) digitalis only led to a renewed compensation of the left-ventricular stroke-work-index, the rise of the left-ventricular filling pressure remained unaffected. It follows from that, in cases of myocardial infarction without cardial decompensation, propranolol requires concomitant digitalisation. In cases of already existent myocardial insufficiency, propranolol can produce an unfavorable increase of the decompensation signs.

Acute Disease↗
PubMed1980

[Nifedipine in acute myocardial infarction (author's transl)].

Nineteen patients in the acute stage of transmural myocardial infarction were given 20 mg nifedipine orally under haemodynamic control. Two groups were differentiated according to the original left ventricular filling pressure: group 1 pressure less than or equal to 15 mm Hg (n1 = 8), group 2 pressure > 15 mm Hg (n2 = 11). In both groups a significant drop in peripheral resistance and thus arterial mean pressure was found 1-2 hours after ingestion of nifedipine. in the compensated patients in group 1 it led to lowering of the left ventricular stroke-work index with virtually unchanged heart rate and constant cardiac index. The lower initial values for stroke-work index in the decompensated group 2 were not influenced by nifedipine. In the patients of group 2 a small but yet significant lowering of the left ventricular filling pressure was obtained with original values of 22.6 mm Hg on average. Thus the use of nifedipine in the acute phase of myocardial infarction leads to a more economical cardiac action in compensated patients. In decompensated cases the results do not deteriorate, and the tendency to reduction of left ventricular filling pressure may even result in a recompensation of the left ventricle.

Aged↗
PubMed1980

[Anti-arrhythmic effect of dazolicin. Clinical-pharmacological research].

8-Chloro-6-[(1-isopropyl-3-imidazolin-2-yl)-methyl]-1,6-benzoperhydrothiazocin-hydrochloride (dazolicin, ucb B 192) is a new antiarrhythmic drug with direct membrane action which was applied both orally and parenterally. The immediate antiarrhythmic effect of a single i.v. injection of 150 mg of dazolicin on the average was investigated in 28 patients with various types of arrhythmia. After i.v. injection the drug proved to have very strong antiarrhythmic potency and rather a low incidence of side effects. Ectopic beats and paroxysmal tachycardias of both ventricular and supraventricular origin were successfully treated with dazolicin. The antiarrhythmic drug significantly increased the duration of both the QRS- and QT-interval after correction for frequency but it had no detectable effects on the atrioventricular conduction time. After i.v. administration the antiarrhythmic effects of the drug lasted for several hours. The elimination half-life of dazolicin was 7 h. Oral treatment with dazolicin was attempted in 10 patients suffering from stable extrasystolic arrhythmia with daily doses ranging from 3 x 25 mg to 3 x 50 mg. In only 4 patients ectopic beats could sufficiently be eliminated. According to the low dosage the maximum serum concentrations after oral application were significantly lower than after i.v. injection. In two patients serious side effects were observed, such as paroxysmal ventricular fibrillation and an increase in frequency and polymorphism of ventricular ectopic beats. In both instances the patients were suffering from congestive heart failure and they had TU abnormalities in the ECG.

Administration, Oral↗
PubMed1979

[Influence of digitalis on pindolol activity in exercise-induced cardiac failure in patients with coronary disease (author's transl)].

The activity of the beta-receptor blocker pindolol (0.4 mg i.v.) was investigated alone and in combination with digitalis (moderately fast loading) in 12 patients with coronary heart disease and without manifest signs of cardiac insufficiency. These patients showed pathological increase of left ventricular filling pressure during exercise testing. The exercise-induced rise of the mean pulmonary arterial and capillary pressures were increased by pindolol. Concurrently the increase of cardiac frequency was clearly diminished during ergometry (from 107/min without pindolol to 96/min, P less than 0.005). Digoxin given orally for an average of 5 days prevented the pressure increase in the pulmonary circulation induced by pindolol during exercise testing and at rest. The frequency reducing effect of pindolol was potentiated by digitalis. Use of digitalis alone did not influence mean exercise-induced pressure increase of the pulmonary circulation. In fact in some cases deterioration of these parameters was observed.

Acetyldigoxins↗
PubMedDate not supplied

Localization of a ventricular tachycardia-focus with multichannel magnetocardiography and three-dimensional current density reconstruction.

The objective of this case report is to determine the accurate localization of a malignant ventricular tachycardia (VT) focus by combining multichannel magnetocardiographic (MCG) information with morphologic data. The localization was obtained by calculating the three-dimensional current density distribution (3D-CDD) on the left ventricular surface. To estimate the accuracy of this localization technique, examinations of a healthy volunteer were additionally performed. The MCG-signals were recorded in a magnetically shielded room by a 49-channel magnetogradiometer. The corresponding morphologic information was recorded by magnetic resonance tomography (MRT). The coordinate systems were matched with the help of markers. The 3D-CDD was calculated by the Philips CURRY software package. The origin of a malignant VT determined by X-ray images of the ablation catheter position during the electrophysiological examination (EPE), was used as the gold standard. This was then compared with the localization results obtained by the 3D-CDD. It was found that the localization coordinates showed a difference of less than 10 mm.

Adult↗