Biomedical subjects

H Kottkamp

Publications and source records attributed to H Kottkamp.

64 records · Page 4Linked to original sources

PubMed1994

[Therapy of AV nodal reentry tachycardia with catheter ablation of the fast retrograde pathway].

AV-nodal reentrant tachycardia (AVNRT) is a common cause of recurrent supraventricular tachycardia. Currently, catheter ablation of either slow or fast pathway are nonpharmacologic options for the treatment of patients with AVNRT. Radiofrequency (RF) catheter ablation of the fast pathway was attempted in 35 patients (aged 46.7 +/- 15 years; 12 m, 23 f) with recurrent AVNRT. RF energy (25-50 watt, 30-90 s) was delivered to the anterior right atrial septum. The catheter was placed posterior to the largest His bundle deflection. AV conduction was monitored during continuous pacing of the high right atrium while the RF current was applied. RF-ablation was acutely successful using a mean of 6.5 +/- 6.2 impulses in 31 patients. Late spontaneous block of the slow pathway occurred in one patient (pat. 17) with an unsuccessful initial attempt of fast pathway ablation. PQ and AH interval increased significantly after the ablation procedure (PQ: from 149 +/- 27 to 208 +/- 34 ms, AH: from 76 +/- 22 to 131 +/- 38 ms; p value: < 0.0001). Acute interruption of retrograde VA conduction was the result in 23 patients. Six patients (17%) had a recurrence of AVNRT during a follow-up period of 11.9 +/- 7.5 months. Five of 6 patients underwent a second successful procedure. Complete AV block occurred in 3 of the first 10 consecutive patients and in none of the subsequent 25 patients (overall incidence: 8.6%). Thus, RF ablation of the fast retrograde pathway is an effective method for the curative treatment of AVNRT.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Atrioventricular nodal reentry tachycardia: electrophysiologic comparisons in patients with and without 2:1 infra-His block.

Patients with atrioventricular nodal reentry tachycardia (AVNRT) occasionally may demonstrate a 2:1 infra-His block during tachycardia. However, the electrophysiologic background of this phenomenon has not been established so far. In the present study we compared the electrophysiologic parameters of 10 consecutive patients with a transient 2:1 infra-His block during AVNRT of the common type (Group A) with those of 17 consecutive patients without this phenomenon during tachycardia (Group B). Transient 2:1 infra-His block occurred without termination of the tachycardia in all 10 patients of Group A. The tachycardia sustained despite intermittent or permanent conduction disturbance of the infrahisian tissue in 8 of these 10 patients. In comparison, the electrophysiologic parameters of 17 patients without 2:1 block during AVNRT of the common type (Group B) were analyzed. A significantly longer antegrade (318 +/- 58 ms vs. 259 +/- 50 ms) and retrograde (308 +/- 59 ms vs. 239 +/- 20 ms) AV conduction capacity could be demonstrated in these patients. The tachycardia cycle length did not differ significantly between the two groups, although the mean tachycardia cycle length was 48 ms longer in patients of Group B. These observations demonstrate an advanced conduction capacity in patients with a transient infra-His block during AVRNT of the common type. This study underlines that the reentry circuit in AVNRT is not necessarily dependent on infrahisian tissue.

Adult↗

PubMed1993

[Torsade de pointes].

Torsade de pointes (TDP) is a polymorphic ventricular tachycardia with a particular electrocardiographic pattern of continuously changing ("twisting") morphology of the QRS complex occurring in the setting of delayed myocardial repolarization (i.e., prolongation of the QT interval). TDP may develop in the setting of an idiopathic disorder (Jervell/Lange-Nielsen syndrome, Romano-Ward syndrome, sporadic long QT syndrome) or may be induced by pharmacologic agents which prolong the QT interval, as well as by other clinical circumstances under which repolarization is delayed (e.g., hypokalemia, hypomagnesemia, bradycardia) (acquired long QT syndrome). Since the treatment of TDP strongly differs from that of conventional ventricular tachycardia, correct diagnosis is critical as it guides the treating physician in selecting the appropriate mode of therapy. In this paper mainly the electrocardiographic criteria presently used for the correct identification of this unusual form of ventricular arrhythmia are presented. Additionally, the potential mechanisms and therapeutic modalities of TDP are discussed.

Anti-Arrhythmia Agents↗

PubMed1993

[Oral anticoagulation for prevention of thromboembolism in non-rheumatic atrial fibrillation: indications, effectiveness and risk].

Oral anticoagulation in patients with rheumatic heart disease for prevention of systemic thromboembolism is accepted clinical practice. The incidence of stroke in patients with nonrheumatic atrial fibrillation is about five times the rate of patients in sinus rhythm. However, contradictory findings in several small retrospective studies have precluded determination of a gold standard for patients with nonrheumatic atrial fibrillation so far. Recently, the results of five prospective, placebo-controlled studies in patients with nonrheumatic atrial fibrillation treated with anticoagulation have been published. A consistent risk reduction of thromboembolism ranging from 37 to 87% in patients treated with warfarin was reported. This risk reduction occurred in excess of a relatively low incidence of intracerebral and/or fatal bleeding complications. The efficacy of prevention of thromboembolism was comparable for high intensity anticoagulation (International Normalized Ratio (INR) 2.8-4.2) and low dose anticoagulation (INR 1.5-2.7). However, fatal and/or intracerebral bleedings only occurred with INR > or = 2.6. In subgroup analysis, recent congestive heart failure, arterial hypertension, and previous apoplex or arterial thromboembolism were independent clinical predictors of increased risk for thromboembolism, whereas results in patients with chronic and intermittent atrial fibrillation were comparable. In 69 patients with lone atrial fibrillation, no single event occurred in the follow-up period. Thus, lone atrial fibrillation does not seem to carry an increased risk for stroke when strict criteria for diagnosis of lone atrial fibrillation are applied. In two of the five studies, aspirin was additionally randomized. Since contradictory findings resulted, the role of aspirin for prophylaxis of stroke still needs to be determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗

PubMed1993

[Anisotropic impulse conduction characteristics in chronic myocardial infarct. The importance for initiation and perpetuation of ventricular tachycardia].

The underlying mechanism of most ventricular tachycardias in the setting of chronic myocardial infarction is reentrant excitation. At that time, the active membrane properties like upstroke velocity and amplitude of action potentials of muscle fibers surviving in the border zone of the infarction have returned nearly completely to normal. Anisotropic conduction characteristics, however, importantly contribute to the electrophysiologic properties of the epicardial and/or endocardial border zones in chronic myocardial infarction. In normal myocardial tissue with tight coupling between muscle fibers, conduction velocity is slower for impulses propagating transverse to fiber orientation compared to longitudinal to fiber orientation due to a higher effective axial resistivity ("uniform" anisotropy). With infarct healing, connective tissue invading into the epicardial border zone separates surviving muscle fiber bundles and thereby decreases cell-to-cell coupling ("non-uniform" anisotropy). In this setting, excitation waves propagate transverse to fiber orientation in an irregular sequence and conduction velocity in this direction is significantly reduced without occurrence of acute ischemia. Block of conduction waves propagating longitudinally to fiber orientation may lead to activation of the area distal to the block with long delay by very slow transverse wavefronts. This long delay allows fibers proximal to the line of block to regenerate excitability, and reentrant excitation may be initiated. The common pathway of figure-eight tachycardias preferentially orientates longitudinally to fiber orientation. Very slow conduction transverse to fiber orientation at the pivoting points of reentrant circuits may lead to the occurrence of excitable gaps.

Animals↗

PubMed1992

Efficacy and tolerability of slow-release gallopamil in patients with stable exercise-inducible angina pectoris.

The anti-ischemic properties and tolerability of a slow-release formulation (SR) of gallopamil were investigated in 118 patients with exercise-inducible ST-segment depression and stable angina pectoris in this double-blind, randomized, placebo-controlled, multicenter study. After a placebo run-in period (A) of 2-7 days and a 7-day open therapy period (B) with gallopamil SR, the patients were randomized to a double-blind 7-day period (C) to receive placebo or gallopamil SR 100 mg twice a day. Each patient was submitted to gradual upright bicycle ergometry and electrocardiography (ECG) at rest on the last 2 days of each period at 6 and 12 h postadministration (p.a.) In period C, exercise time and exercise tolerance remained significantly prolonged at 6 and 12 h after gallopamil SR administration in comparison with the placebo values. Additionally the sum of ST-segment depression and maximal ST-segment depression were significantly reduced by gallopamil SR at 6 h p.a. as were the frequency of angina attacks and nitroglycerin consumption. Four patients were withdrawn from the study because of gallopamil-related adverse events, which, however, were not serious. Constipation was noted in 2.5% of the patients. These data suggest that gallopamil SR is effective in reducing exercise-inducible ST-segment depression and increasing exercise tolerance with no serious adverse effects in patients with stable angina pectoris.

Adult↗

PubMed1992

[Left atrial myxoma].

Left-atrial myxomas produce a broad array of clinical symptoms depending on their location, size, and morphology. The clinical presentation is characterized by obstruction of blood flow, systemic embolism, and unspecific systemic effects. Within 6 weeks, three patients presented in our clinic with left-atrial myxomas. Primary differential diagnoses were infective endocarditis, circulatory collapse, and transient ischemic attack of unknown origin. In all cases diagnosis was made with echocardiography (m-mode, 2D, TEE). In this review the etiology, epidemiology, and pathology are reported briefly. The variety of clinical symptoms with the corresponding differential diagnosis is presented systematically and discussed with our patients. Diagnostic, therapeutic, and prognostic aspects are summarized.

Adult↗

PubMed1992

[Biophysical aspects of high frequency catheter ablation. Studies of the significance of sudden changes in impedance].

UNLABELLED: To determine the effects and the underlying mechanisms of sudden rise of impedance during radiofrequency (RF) catheter ablation, 60 RF applications were delivered to isolated preparations of ventricular myocardium at three different power levels (mean: 3.7, 11.3, 19.3 watts). Pulse duration was 30 s, current voltage and catheter tip temperature were continuously monitored. Impedance rise occurred during 34 of 60 applications; the incidence of impedance rise increased at higher power levels. Impedance rise was significantly more often observed when the preparations were superfused with heparinized blood compared to saline solution (p less than 0.05). Catheter-tip temperature during radiofrequency application without impedance rise was significantly lower compared to applications with impedance rise (mean = 108 degrees C vs. 121 degrees C, p less than 0.01). The increase of catheter-tip temperature and maximal-tip temperature following impedance rise was significantly higher in blood when compared to saline solution (mean = +48 degrees C vs. +13 degrees C (p less than 0.001), Tmax: 121 degrees C vs. 245 degrees C). Following impedance rise, insulation defects of the electrode catheter and vaporized crater formation of the myocardium was often observed. CONCLUSIONS: During radiofrequency catheter ablation impedance rise occurs following overheating of the catheter electrode (greater than 110 degrees C). After impedance rise, catheter-tip temperature markedly increases. Insulation defects of the catheter and vaporized craters in the myocardium frequently occur after impedance rise. The results have important implications for the clinical use of RF-currents for catheter ablation; energy application should be immediately stopped after the occurrence of impedance rise.

Animals↗

PubMedDate not supplied

Anisotropic conduction characteristics in ischemia-reperfusion induced chronic myocardial infarction.

OBJECTIVES: Anisotropic properties of cardiac tissue play an important role in initiation and perpetuation of ventricular tachycardia. However, anisotropic conduction properties in different morphologic types of chronic myocardial infarctions as well as frequency dependency still need to be elucidated. In the present study, the characteristics of anisotropic conduction were investigated in situ in the setting of ischemia-reperfusion induced chronic myocardial infarction. METHODS: Myocardial infarction was induced in 12 dogs by a percutaneous transcatheter left anterior descending coronary artery occlusion-reperfusion technique. Four additional dogs served as normal controls. After 14 to 20 days, epicardial mapping was performed using simultaneous unipolar recordings from 240 electrodes of a plaque electrode array placed on the epicardial border zone overlying the infarctions. Constant rate pacing with five cycle lengths (CL) ranging from 500 to 200 ms as well as programmed electrical stimulation (PES) with four basic cycle lengths (BCL) ranging from 430 to 300 ms and single extrastimuli (S2) were performed. RESULTS: Two anatomically different patterns of epicardial surface morphology were analyzed, designated as type I and type II. In seven animals, there was a continuous thin layer of surviving epicardial muscle fibers overlying the infarction (type I). During pacing with CL of 500 vs 200 ms, conduction velocity longitudinal to fiber orientation (theta L) decreased significantly in the infarcted animals compared to control group (10.9% vs 5.2%, p < 0.05) whereas conduction velocity transverse to fiber axis (theta T) decreased to a similar degree in control and infarcted animals (6.9 vs 7.4%, n.s.). After premature stimulation, there was considerably greater reduction in theta L in infarcted animals than in controls (39.8% vs 31.5%, p < 0.05) whereas theta T decreased to a similar extend in infarcted and control animals (22.2% vs 21.4%, n.s.). During constant rate pacing and premature stimulation, no functional conduction block was induced in type I infarctions. In five animals, the transmural infarctions clearly extended to the epicardial surface, but continuous strands of surviving epicardial muscle fibers traversed the area of necrosis (type II). During PES with S2, functional conduction block and areas of very slow conduction were observed in each case. CONCLUSIONS: In ischemia-reperfusion induced chronic myocardial infarctions, different epicardial patterns of morphology were observed. Anisotropic conduction was frequency dependent in the longitudinal but not in the transverse direction. In type I infarctions, functional conduction block was not inducible during PES whereas in type II infarctions, prerequisites for reentrant arrhythmias like functional conduction block and very slow conduction were induced in each case by single extrastimuli.

Animals↗

PubMedDate not supplied

[Idiopathic left ventricular tachycardia in childhood: typical clinical findings and different therapeutic options].

We report 3 adolescents with structurally normal heart who were referred to hospital due to long-lasting palpitations. Initial 12-lead-ECG showed sustained, monomorphic ventricular tachycardia, right bundle branch block QRS morphology and axis deviation. After failure of different anti-arrhythmic drugs finally the intravenous medication with verapamil led to termination of ventricular tachycardia in all three patients. All clinical findings and the responsiveness to verapamil are consistent with the diagnosis of idiopathic left ventricular tachycardia. In one patient an electrophysiological study was done and increased left ventricular vulnerability was shown. After inducing a tachycardia originating from the left ventricle radiofrequency catheter ablation of the left-posterior fascicle was successfully performed. The tachycardia was not inducible after this ablation. Since that investigation the patient has been asymptomatic without anti-arrhythmic treatment. Two of three patients have been on oral verapamil prophylactically and have been free of symptoms.

Administration, Oral↗