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Biomedical subjects

K H Kuck

Publications and source records attributed to K H Kuck.

At least 55 records · Page 3Linked to original sources
PubMed1997

Atrial fibrillation: maintaining stability of sinus rhythm or ventricular rate control? The need for prospective data: the PIAF trial.

Atrial fibrillation is one of the most commonly encountered clinical arrhythmias. Different treatment options for this rhythm disorder exist with the electrical and/or pharmacological cardioversion to sinus rhythm with subsequent antiarrhythmic drug therapy to prevent recurrences being one of the primary therapeutic goals. Another alternative, however, is represented by the control of the ventricular rate in patients with persistent atrial fibrillation. The question of which these two strategies should be preferred in the majority of patients with atrial fibrillation has not been studied in a prospective way. Given the background of conflicting data with respect to the prognostic impact of atrial fibrillation and of the increasing evidence concerning the risks of antiarrhythmic drug treatment in atrial fibrillation, a prospective multicenter trial has been initiated to compare these two therapeutic alternatives prospectively. Patients will be randomly assigned to cardioversion with subsequent antiarrhythmic drug therapy to prevent recurrent atrial fibrillation or to a therapy aiming exclusively at control of the ventricular rate during persistent atrial fibrillation. All patients will receive anticoagulation by means of warfarin (target INR 2.5-3.5) to prevent thromboembolic complications. The rationale and the design of the PIAF trial (Pharmacological intervention in Atrial Fibrillation) are discussed below. The pilot phase of this study has begun patient enrollment in the spring of 1995.

Adolescent↗
PubMed1997

Arrhythmias in hypertrophic cardiomyopathy.

Supraventricular and ventricular arrhythmias, particularly nonsustained ventricular tachycardia, and ventricular premature beats are a common finding in patients with hypertrophic cardiomyopathy. Several investigations have demonstrated that nonsustained ventricular tachycardia on Holter monitoring is associated with an increased risk of sudden cardiac death. It has been a long lasting controversial discussion whether suppression of these arrhythmias with drugs, such as amiodarone is capable to reduce the incidence of sudden cardiac death. While recent studies have indicated that nonsustained ventricular tachycardia in asymptomatic patients without additional risk factors, such as a positive family history of sudden cardiac death or syncope should not be treated prophylactically with amiodarone. Symptomatic patients with sustained ventricular tachycardias and/or syncope related to ventricular arrhythmias should undergo ICD implantation. The implantation of an ICD in asymptomatic patients should be limited to those who have several risk factors for sudden cardiac death. It is questionable whether other risk stratifiers, such as programmed electrical stimulation may be helpful to identify asymptomatic patients who are at risk to die suddenly. Moreover, whether the demonstration of electrocardiogram fractionation during electrophysiological study is superior to the induction of sustained ventricular arrhythmias for risk stratification, needs further investigation.

Anti-Arrhythmia Agents↗
PubMed1997

Mapping of the coronary sinus and great cardiac vein using a 2-French electrode catheter and a right femoral approach.

INTRODUCTION: Local electrograms recorded from the coronary sinus and great cardiac vein provide important information for the diagnosis of various arrhythmias and identification of target sites for ablation of left-sided accessory pathways. One limitation of present techniques is the inability, in many cases, to probe the great cardiac vein at the anterior mitral annulus. We tested the feasibility of a new technique for catheterization of the coronary sinus and great cardiac vein by means of a small-diameter electrode catheter advanced via a right femoral approach through an angiography catheter. METHODS AND RESULTS: Of 22 patients (12 men and 10 women; ages 44.5 +/- 13.4 years) undergoing radiofrequency ablation of a supraventricular tachycardia, cannulation of the coronary sinus orifice using a 6-French 1L or 2L Amplatz catheter was achieved in 20 patients (91%) within 0.9 +/- 0.6 minutes; after cannulation, a 2-French octapolar electrode catheter with a soft radiopaque tip and a 3-mm interelectrode distance could be advanced in all 20 patients through the guiding catheter to the great cardiac vein in the anterior region of the AV sulcus within 0.8 +/- 0.7 minutes. Atrial and ventricular local potentials were recorded all along the mitral annulus during sinus rhythm, atrial and ventricular pacing, or supraventricular tachycardia. Variation of local potential amplitude never exceeded 20% of the mean and presented similar stability at all annular regions. The arrhythmogenic substrate was identified in all patients. Of 18 patients with 21 left-sided accessory pathways, an accessory pathway potential could be recorded at the ablation site by one or more adjacent epicardial electrode pairs in 10 pathways. No procedure-related complications were observed. CONCLUSIONS: The technique introduced in this study proved feasible in 91% of patients. Its main advantages are the simplicity and rapidity of coronary sinus cannulation and the ability to advance the electrode catheter to the anterior cardiac vein. In addition, closely spaced bipolar electrograms resulted in enhanced atrial, ventricular, and accessory pathway potential resolution.

Adult↗
PubMed1997

Clinical recurrences after successful accessory pathway ablation: the role of "dormant" accessory pathways.

INTRODUCTION: Recurrence of clinical symptoms after radiofrequency catheter ablation of an accessory atrioventricular pathway (AP) may be due to the late manifestation of an additional AP that was not detected during the initial ablation session. It was the purpose of this study to elucidate the phenomenon of these "dormant" APs. METHODS AND RESULTS: Of 1280 consecutive patients who underwent radiofrequency catheter ablation of an AP, 54 patients (4.2%) developed clinical symptoms postablation, necessitating a repeat ablation session. Recurrence of conduction over the AP targeted at the initial ablation session was found in 45 patients, whereas in the other 9 patients (0.7%) the manifestation of a previously unnoticed AP had caused symptom recurrence. Retrospective analysis of the data from these patients' ablation sessions revealed that the late manifesting AP was ablated at a site clearly different from that of the initially targeted AP, and that the manifestation of conduction over a previously "dormant" AP occurred significantly later than the recovery of a presumably ablated AP. Seven (78%) of the 9 "dormant" APs were concealed, and none exhibited decremental conduction properties. CONCLUSION: The incidence of clinical recurrences mediated by the late manifestation of conduction over a previously "dormant" AP is low. The lack of an anatomic vicinity of these predominantly concealed APs with the initially targeted AP and the lack of evidence for their presence during the initial ablation session suggest intermittent conduction as the most likely explanation for their late manifestation.

Adult↗
PubMed1996

Radiofrequency current catheter ablation of accessory atrioventricular pathways in Ebstein's anomaly.

BACKGROUND: In patients with Ebstein's anomaly, localization of accessory pathways (APs) may be impeded by abnormal local electrograms recorded along the atrialized right ventricle and by the presence of multiple APs. The impact of these factors on radiofrequency (RF) current catheter ablation of APs has not been evaluated yet. METHODS AND RESULTS: Twenty-one patients with Ebstein's anomaly and reentrant atrioventricular tachycardias underwent electrophysiological evaluation and subsequent attempts at RF catheter ablation. Thirty-four right-sided APs were found, with 30 located along the atrialized ventricle. Local electrograms in this region were normal in 10 patients but fragmented in 11. Fragmented electrograms prevented the clear distinction between atrial and ventricular activation potentials as well as the identification of AP potentials. Right coronary artery mapping was performed in 7 patients. Abolition of all 26 APs was achieved in the 10 patients with normal local electrograms and in 6 of 11 patients with abnormal electrograms. Right coronary artery mapping allowed AP localization and ablation in 5 patients. In the 5 patients with abnormal electrograms and a total of 8 APs, 6 APs could not be ablated. Unsuccessfully treated patients received antiarrhythmic drugs. During 22 +/- 12 months of follow-up, 5 patients had clinical recurrences, including 4 who had undergone a successful RF procedure. CONCLUSIONS: In patients with Ebstein's anomaly and reentrant atrioventricular tachycardias, factors likely to account for failure of RF catheter ablation include an AP located along the atrialized right ventricle and the abnormal morphology of endocardial activation potentials generated in this region.

Action Potentials↗
PubMed1996

Programmable polarity: effects on pacing and sensing of bipolar steroid-eluting leads.

Presently available bipolar pacemakers connected to bipolar leads allow the programming of polarity to either bipolar or unipolar configuration. The bipolar configuration improves sensing because of its lack of oversensing. In respect to the pacing impulse, it may be beneficial to program the bipolar to unipolar configuration, because the unipolar pacing configuration seems to lead to lower pacing thresholds. The aim of the study was to investigate the effects of the two configurations on pacing and sensing in 11 patients with a new ventricular steroid-eluting lead (Encor Dec 033-301, Telectronics Inc.) connected to the same types of VVI(R) pacemakers. Follow-up was 12 months after implantation. Pacing was assessed by pulse duration thresholds at 0.8- 1.6-, and 2.5-V pulse amplitude and by pacing impedance. Parameters for sensing included sensing thresholds, R wave amplitudes, and amplitude of intrinsic deflection. Pulse duration thresholds were similar for the two configurations. At implantation, pacing impedance was significantly higher with bipolar (672 +/- 60 omega) than with unipolar pacing configuration (626 +/- 82 omega, P < 0.005). The difference lasted until 1 month after implantation (bipolar: 670 +/- 49 omega; unipolar: 63053 omega, P < 0.01). No significant differences were detected after 3 (bipolar: 683 +/- 63 omega; unipolar: 662 +/- 70 omega) and 12 months (bipolar: 658 +/- 64 omega; unipolar: 660 +/- 63 omega) between the 2 configurations. Although intrinsic deflections of ventricular electrograms were different, mean R wave amplitudes were similar in unipolar and bipolar configuration. Pacing and sensing characteristics of unipolar and bipolar configuration were similar for the studied bipolar pacing lead. Pacing impedance was initially higher for bipolar than for unipolar configuration and equilibrated within 3 months after implantation.

Aged↗
PubMed1996

Reliability and variability of impedance measured by real-time telemetry.

UNLABELLED: With the aim to detect dysfunction of pacing leads, most present-day pacemakers measure pacing impedance by means of real-time telemetry. The recommended setting for impedance measurement is 5.0 V for pulse amplitude and 0.5 ms for pulse duration. Availability of reliable settings would facilitate impedance measurements during follow-up. The purpose of the present study was twofold: (1) to assess whether telemetrically measured impedance of the studied pacemaker is similar to impedance measured at implantation; and (2) to evaluate whether the pacemaker setting influences telemetrically measured impedance. Sixty-five consecutive patients receiving VVI(R) pacemakers were studied; in all patients, impedance measured at implantation by a pacing system analyzer was compared to measurements obtained telemetrically within 1 day after implantation. In 44 other patients, impedance was determined 3 months after implantation at 60 and 120 ppm (n = 44), twice at 60 ppm (n = 42), and 12 months after implantation at 60 ppm (n = 34). For each measurement, pulse amplitude was programmed to 0.8, 1.6, 2.5, 5.0, and 8.0 V, and pulse duration to 0.05, 0.25, 0.50, and 1.00 ms. Impedance at implantation (606 +/- 113 ohms) did not differ from the data obtained with telemetry (629 +/- 113 ohms; P = NS). Different pacing rates, repeat measurements, and follow-up time failed to show any influence on impedance. Measurement tolerance was < 10% for 15 of 19 studied settings other than 5.0 V and 0.5 ms. CONCLUSION: The studied pacemakers provide reliable data for telemetrically measured impedance. Telemetrical impedance does not necessarily have to be measured at 5.0 V and 0.5 ms. These findings should be considered for measurement and interpretation of real-time telemetry impedance during follow-up.

Aged↗
PubMed1996

Radiofrequency catheter ablation of left atrial tachycardia originating within the pulmonary vein in a patient with dextrocardia.

A case is presented of a 38-year-old male with dextrocardia in whom radiofrequency current ablation of an incessant atrial tachycardia originating within the infero-lateral pulmonary vein was achieved. Activation mapping with detection of the earliest atrial activation was used for identification of the arrhythmogenic focus. In addition to fluoroscopy, transesophageal echocardiography was used for catheter guidance during the transseptal puncture. The present experience suggests that location of an arrhythmogenic focus within the pulmonary venous system should be considered whenever early atrial activation during ectopic atrial tachycardia is recorded at the junction between the left atrium and the pulmonary veins.

Adult↗
PubMed1996

[Anti-arrhythmia therapy after myocardial infarct: preliminary results of EMIAT and CAMIAT studies].

This article reviews the preliminary results of the EMIAT and CAMIAT postinfarction trials which were published in early 1996. The trials were conducted independently from each other and both have a randomized, placebo controlled design to assess the efficacy of the class III agent amiodarone in patients with acute myocardial infarction. Differences in patient inclusion criteria and study endpoints are pointed out and major findings from the analysis of 1,486 patients enrolled in EMIAT and 1,202 patients enrolled in CAMIAT are presented. A reduction in the 2-year total mortality could not be demonstrated in EMIAT, but both trials showed unanimously that amiodarone therapy in patients with myocardial infarction significantly reduced the incidence of arrhythmic death and resuscitated cardiac arrest over a 2-year follow-up period.

Adult↗
PubMed1995

[Do steroid-eluting pacemaker electrodes permit programming at lower pacemaker pulse amplitudes?].

A study was undertaken on 107 patients (68 men, 39 women; mean age 68 [29-100] years) with steroid-eluting ventricular electrodes to determine whether in general these electrodes make it possible routinely to set pacemaker impulses at 2.5 V instead of 5.0 V with an impulse duration of 0.5 ms. 3-12 months after implantation, impulse duration thresholds were 0.27 +/- 0.20 ms at 0.8 V, 0.13 +/- 0.09 ms at 1.6 V and 0.08 +/- 0.05 ms at 2.5 V impulse amplitude. Thus, employing a 100% margin of safety, it was possible to set the pacemakers of 103 among the 107 patients at 2.5 V and 0.5 ms. In four patients it was not possible to achieve the 2.5 V and 0.5 ms setting. With one exception (stimulation threshold rose immediately after a current accident) no circumstances arose under which thresholds increased. These results demonstrate that, using steroid-eluting electrodes, ventricles can be reliably stimulated with 2.5 V and 0.5 ms in 96% of patients. However, since it is not possible in all patients, optimal stimulation parameters must be determined in each patient even when steroid-eluting electrodes have been implanted.

Adult↗
PubMed1995

Metoprolol versus sotalol in the treatment of sustained ventricular tachycardia.

The efficacy of sotalol in the treatment of sustained ventricular arrhythmias has been proved; however, whether its antiarrhythmic effect is due to a beta-blocking activity, a class III antiarrhythmic activity, or a combination of both is not known. We conducted a prospective randomized study to compare the effects of metoprolol, a "pure" beta-blocking agent, and of sotalol, a beta-blocking agent with additional class III antiarrhythmic properties, in 34 consecutive patients with documented sustained monomorphic ventricular tachycardia (VT) unrelated to transient causes. After undergoing baseline programmed electrical stimulation (PES-1) to assess arrhythmia inducibility, the patients were randomly assigned to a (double-blind) treatment of either metoprolol (16 patients) or sotalol (18 patients). Before the chronic regimen was initiated, arrhythmia inducibility was reassessed after the intravenous administration of either 0.15 mg/kg metoprolol or 1.5 mg/kg sotalol (PES-2), according to drug assignment. During the chronic oral regimen, a third PES (PES-3) was performed after a median follow-up of 72 days. Resting and exercise ECG, Holter monitoring and echocardiography were performed at baseline and during follow-up. During a 2-year follow-up, a non-fatal arrhythmia recurred in 1 patient of the metoprolol arm and in 5 patients of the sotalol arm; 1 patient in the latter group died suddenly 2 months after the recurrence, while receiving amiodarone therapy. Intention-to-treat analysis showed no difference in the incidence of arrhythmia recurrence, sudden death, or total mortality between the two groups. During PES-1, a sustained ventricular arrhythmia was inducible in 18 of 34 patients (53%), 8 in the metoprolol and 10 in the sotalol arm.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1995

Programming of the pacing impulse in pacemakers connected to steroid lead systems.

The purpose of the study was to compare the feasibility of low amplitude output programming (2.5 V/0.5 msec) 3 or more months after pacemaker implantation in patients receiving steroid and nonsteroid lead systems. Chronic pacing voltage, current, and energy thresholds were determined from 0.05- to 1.0-msec pulse duration in 44 patients with steroid lead systems, and in 36 patients with nonsteroid lead systems; all patients received pacemakers from the same manufacturer, which utilized the same programming and telemetry features. Chronaxie, pulse duration at the lowest pacing current, and energy were assessed from individual threshold curves. Steroid-eluting leads had significantly lower pacing voltage, current, and energy thresholds than nonsteroid leads. A 100% safety threshold margin could be achieved in 43 (98%) patients with steroid lead systems and in 27 (75%; P < 0.05) patients with nonsteroid lead systems with output programming of 2.5 V/0.5 msec. Chronaxie (0.22 +/- 0.17 msec vs 0.44 +/- 0.31 msec; P < 0.05), pulse duration at lowest pacing current (0.28 +/- 0.12 msec vs 0.49 +/- 0.22 msec; P < 0.05), and pulse duration at lowest pacing energy (0.31 +/- 0.17 msec vs 0.53 +/- 0.22 msec; P < 0.05) were significantly shorter for steroid than for nonsteroid lead systems. In 42 patients of the former group, a 100% safety margin could be maintained either with a 2.5 V/0.3 msec or with a 1.6 V/0.5 msec output. Conclusions Low amplitude output programming can be obtained in almost all pacemakers connected to steroid-eluting lead systems, and in a significantly higher number of patients than when connected with nonsteroid leads systems.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

[Carotid sinus massage in pacemaker patients with heart rates about the pacemaker frequency].

UNLABELLED: The delivery of pacing impulses is inhibited in patients with VVI(R) pacemakers whose intrinsic heart rate is above pacing rate. Efficacy of the pacing impulse can be evaluated on surface ECG by application of a magnet on the pacemaker which temporarily induces asynchronous pacing. Carotid sinus massage can alternatively lower intrinsic heart rate below pacing rate. The study investigates in how many patients carotid sinus massage lowers heart rate below pacing rate during follow-up, and whether the efficacy is reduced in the presence of a pacing rate programmed below the nominal setting. Patients with pacing rates 61-72 ppm (group I) were compared to patients whose pacemakers were programmed to 51-60 ppm (group II) and 40-50 ppm (group III). A right- and leftsided carotid sinus massage was performed in 119 consecutive patients. Right-sided carotid sinus massage was positive in 64 and left-sided in 53 patients. The second, left-sided carotid sinus massage induced pacing in additional 11 patients. In general, carotid sinus massage lowered heart rate below pacing rate in 75 (70%) patients. Induction of pacing was significantly lower (p < 0.02) in group III (n = 31/57; 54%) compared to group I (n = 17/20; 85%). No differences were detected between group II (n = 27/42; 64%) and group I. CONCLUSION: Carotid sinus massage is a useful method for induction of pacing in patients whose intrinsic heart rate is above pacing rate.

Adult↗
PubMed1995

Therapeutic consequences of newer studies addressing the problem of myocardial ischemia and ventricular arrhythmias.

Direct evidence from pathologic-anatomical studies in victims of sudden cardiac death has been given for acute ischemia (caused by either an acute thrombus, plaque fissuring or an organizing thrombus) to play a major role in the genesis of sudden cardiac death. Furthermore, indirect data on the effects of drugs in the setting of acute myocardial infarction have demonstrated that treating patients with beta-blocking agents is more beneficial than treating them with a pure anti-arrhythmic drug such as lidocaine. Whereas lidocaine, which also reduces the incidence of ventricular fibrillation in the setting of acute myocardial infarction, may produce an excess of mortality, beta-blockers reduce ventricular fibrillation and are associated with a prolonged survival. Further, indirect evidence on the role of ischemia in ventricular arrhythmias is given in patients with chronic ischemic heart disease by several studies on coronary revascularization and by studies on antiarrhythmic drugs versus beta-blockers in the same situation. In conclusion, there is clear evidence from studies of coronary revascularization and from studies on drug intervention in different patient populations with ischemic heart disease at risk for ventricular arrhythmias and/or for sudden cardiac death that ischemia plays an important role in the genesis of these arrhythmias.

Anti-Arrhythmia Agents↗
PubMed1995

[Modern electrodes with and without steroid: effects on stimulation current of cardiac pacemakers].

The aim of the investigation was to test whether new leads without steroid, a meshwire tip leads (Ionyx 4180, CPI; n = 10) and a carbon tip lead (Facet ITP 13, Vitatron; n = 10), have electrical characteristics similar to a new steroid-eluting tip lead (CapSure SP 4023, Medtronic; n = 10) and their impact on the pacemaker's pacing current. Pacing thresholds, impedance, and R-wave amplitudes measured at implantation were similar for the three leads. One, 4 and 12 weeks after implantation both nonsteroid leads had significantly higher pacing thresholds at 0.1 and 0.3 ms pulse duration in comparison to the steroid lead (after 12 weeks at 0.3 ms steroid: 0.9 +/- 0.2 V, carbon: 2.1 +/- 0.5 V; meshwire: 1.5 +/- 0.5 V). This result was restricted to the carbon lead after 52 weeks. At 0.5 ms pulse duration higher pacing thresholds were obtained for the carbon lead (after 12 weeks at 0.5 ms; steroid: 0.8 V, carbon: 1.7 +/- 0.6 V; meshwire: 1.1 +/- 0.4 V). Impedance of the steroid lead was 531 +/- 61 ohms, 535 +/- 54 ohms, and 511 +/- 50 ohms, respectively, after 4, 12, and 52 weeks, whereas the carbon lead had significantly higher values with 652 +/- 84 ohms, 669 +/- 93 ohms, and 657 +/- 107 ohms, respectively. The impedance of the meshwired lead (4 weeks: 585 +/- 92 ohms; 12 weeks: 592 +/- 89 ohms; 52 weeks: 550 +/- 130 ohms) did not differ from the steroid lead.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

[Reopening of completely closed aortocoronary venous bypasses using angioplasty and 24-hour local fibrinolysis].

Recent occlusion of aortocoronary venous bypass grafts had occurred in three patients, aged between 64 and 67 years. In all three recanalization was achieved after 8 hours, two and five days, respectively, of coronary angioplasty combined with local urokinase infusion for 24 hours. The procedure consisted of passing a guide-wire through the occluded bypass graft, the tip of the wire then being advanced to the periphery of the native coronary artery. The balloon was then repeatedly dilated along the length of the graft. Primary opening was not achieved in one of the grafts, and the other two closed again, despite repeated and prolonged balloon dilatation. In all three patients a coronary infusion catheter was then placed into the graft lumen and urokinase (3 mill. units) infused over 24 hours. An angiogram 24 hours later demonstrated an open bypass graft (residual stenosis < 50%). Angiography 9 to 14 weeks later revealed restenosis in one case, but it was reopened by balloon dilatation and stent insertion, while the other two had remained open without significant stenosis.

Aged↗