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Biomedical subjects

K H Kuck

Publications and source records attributed to K H Kuck.

At least 73 records · Page 4Linked to original sources
PubMed1994

[One session diagnostic heart catheterization and balloon dilatation ("prima vista"-PTCA): results and risks].

Percutaneous transluminal coronary angioplasty (PTCA) immediately after elective diagnostic cardiac catheterization ("prima vista"-PTCA) was performed in 124 patients (group 1) with typical angina pectoris (96 men, 28 women; mean age 60 +/- 10 [25-86] years). In a case-control analysis the results and complications, as well as the volume of contrast media and amount of radiation exposure were compared with a group of patients with similar symptoms (group 2) who during the same period had undergone angiography at another hospital and subsequently PTCA in our department (96 men, 28 women; mean age 60 +/- 8 [39-78] years). The success rate in group 1 (122 of 138 stenoses: 92.1%) was similar to that in group 2 (122 of 138 stenoses: 88.4%). Complications (coronary artery dissection with occlusion, emergency operation, myocardial infarction) were rare in both groups (8 vs 5; difference not significant). But the combined procedure (group 1) used lower volumes of contrast medium (341 +/- 131 vs 250 +/- 113 ml; P < 0.001) and the cumulative fluoroscopic time was lower (33.7 +/- 19.5 vs 26.5 +/- 12.4 min; P < 0.002). With optimal logistic conditions, "prima vista"-PTCA under elective circumstances is a useful and patient-friendly alternative to the conventional two-session diagnostic and therapeutic procedures.

Adult↗
PubMed1994

Potential of intracardiac ultrasonography as an adjunct for mapping and ablation.

Radio frequency catheter ablation of cardiac tissues has evolved rapidly as the standard therapy for various arrhythmias. Current mapping techniques include fluoroscopy and endocardial ECG recordings. These techniques are time-consuming and give only limited information with regard to cardiac anatomy and pathology. Moreover, fluoroscopy leads to significant radiation exposure to the patient and the operator. Intracardiac ultrasonography is a promising new technique that may improve intracardiac anatomic orientation, reduce radiation exposure, allow better control of lesion formation during radio frequency current application, and identify possible complications such as thrombus formation or perforation. Intracardiac ultrasonography systems that are presently available are limited by insufficient penetration depth and image resolution. Technical refinements are discussed that may improve the applicability of intracardiac echocardiography for electrophysiologic mapping procedures.

Animals↗
PubMed1994

Implantable cardioverter defibrillator compared with antiarrhythmic drug treatment in cardiac arrest survivors (the Cardiac Arrest Study Hamburg).

In 1987, the Cardiac Arrest Study Hamburg (CASH), a prospective, multicenter, randomized controlled study, was started in survivors of sudden cardiac death resulting from documented ventricular tachyarrhythmias. Through December 1991, 230 survivors (46 women, 184 men; mean age 57 +/- 11 years) of cardiac arrest caused by ventricular tachyarrhythmias were randomly assigned to receive either oral propafenone (56 patients), amiodarone (56 patients), or metoprolol (59 patients) or to have an implantable defibrillator (59 patients) without concomitant antiarrhythmic drugs. The primary endpoint of the study was total mortality. In March 1992, the propafenone arm of CASH was stopped because of excess mortality compared with the implantable defibrillator group. This article presents preliminary results of the comparison of implantable defibrillator therapy with propafenone therapy. A significantly higher incidence of total mortality, sudden death (12%), and cardiac arrest recurrence or sudden death (23%) was found in the propafenone group compared with the implantable defibrillator-treated patients (0%, p < 0.05). It was concluded that, in survivors of cardiac arrest, propafenone treatment is less effective than implantable defibrillator treatment.

Amiodarone↗
PubMed1994

Influence of internal current and pacing current on pacemaker longevity.

UNLABELLED: The effects of lower pulse amplitude on battery current and pacemaker longevity were studied comparing the new, small-sized VVI pacemaker, Minix 8341, with the former model, Pasys 8329. Battery current was telemetrically measured at 0.8, 1.6, 2.5, and 5.0 V pulse amplitude and 0.05, 0.25, 0.5, and 1.0 msec pulse duration. Internal current was assumed to be equal to the battery current at 0.8 V and 0.05 msec. Pacing current was calculated subtracting internal current from battery current. The Minix pacemaker had a significantly lower battery current because of a lower internal current (Minix: 4.1 +/- 0.1 microA; Pasys: 16.1 +/- 0.1 microA); pacing current of both units was similar. At 0.5 msec pulse duration, the programming from 5.0-2.5 V pulse amplitude resulted in a greater relative reduction of battery current in the newer pacemaker (51% vs 25%). Projected longevity of each pacemaker was 7.9 years at 5.0 V and 0.5 msec. The programming from 5.0-2.5 V extended the projected longevity by 2.3 years (Pasys) and by 7.1 years (Minix). The longevity was negligibly longer after programming to 1.6 V. CONCLUSION: extension of pacemaker longevity can be achieved with the programming to 2.5 V or less if the connected pacemakers need a low internal current for their circuitry.

Aged↗
PubMed1994

Catheter-induced mechanical conduction block of right-sided accessory fibers with Mahaim-type preexcitation to guide radiofrequency ablation.

BACKGROUND: Accessory pathways originating at the tricuspid annulus that exhibit decremental antegrade conduction properties (Mahaim-type preexcitation) are amenable to radiofrequency (RF) current catheter ablation. However, a reliable and reproducible strategy for mapping and ablation of these fibers is lacking. METHODS AND RESULTS: Eleven patients with preexcited atrioventricular tachycardia involving a decrementally conducting antegrade accessory pathway underwent complete electrophysiological evaluation and subsequent attempts at RF catheter ablation. Mechanical conduction block at the subannular level of the atrial input to the accessory fiber was induced by catheter manipulation in 8 patients, in 2 of them during atrial fibrillation. RF current was delivered, after resumption of preexcitation, to the site of mechanical block during atrial pacing (n = 6) or atrial fibrillation (n = 2) and eliminated the accessory pathway in all 8 patients. In another patient, mechanical block was not observed, but ablation of the atrial accessory fiber insertion was achieved at the subannular level during atrioventricular tachycardia. The anatomic site of ablation along the tricuspid annulus was anterolateral (n = 1), lateral (n = 3), or posterolateral (n = 5). Failures were encountered in the first patient of the series in whom ablation attempts were directed at the ventricular insertion of the accessory fiber and in a patient in whom ablation of the atrial insertion was attempted at the supraannular level. Recurrence of preexcitation within 12 hours was observed in 5 of 6 patients in whom ablation had been achieved during atrial pacing. Eventually successful repeat sessions were performed the following day using a simplified ablation approach. Thus, a median of 5 RF pulses (range, 1 to 26) per accessory fiber eliminated conduction in 9 (82%) of the 11 patients in 1.9 +/- 0.9 sessions. During a follow-up of 9.5 +/- 2.3 months, preexcitation recurred in 1 patient. CONCLUSIONS: The atrial origin of accessory connections with Mahaim-type preexcitation is apparently confined to the anterolateral-to-posterolateral region of the tricuspid annulus. Mechanical conduction block in the atrial input to the accessory fiber induced at the subannular level by catheter manipulation provides an optimal marker to locate the ablation site, even during atrial fibrillation. To expose early recurrence of antegrade accessory pathway conduction, intermittent atrial pacing in the 12 hours after ablation is advisable; in cases of recurrence, a repeat procedure can readily be performed using just the ablation catheter advanced to the target site at the tricuspid annulus.

Adult↗
PubMed1994

Anatomic, electrical, and mechanical factors affecting bipolar endocardial electrograms. Impact on catheter ablation of manifest left free-wall accessory pathways.

BACKGROUND: The use of bipolar endocardial electrogram characteristics to guide radiofrequency (RF) current catheter ablation of accessory pathways (APs) has been advocated by several investigators. However, the influences of a varying anatomy of the AP and the atrioventricular groove, of different ablative approaches, and of RF current pulses preceding the final pulse have not been adequately addressed. METHODS AND RESULTS: Local bipolar endocardial electrograms were retrospectively analyzed in a uniform cohort of 62 consecutive patients with a single manifest AP located on the left free wall; in all patients, the AP had been ablated by a uniform approach with a single catheter advanced retrogradely toward the mitral annulus. Electrogram parameters assessed were the presence or absence of a presumed AP potential, the atrial-to-ventricular (A/V) amplitude ratio, the A-V interval, and the onset of delta wave to local ventricular activation (delta-V) interval. The AP location was classified on fluoroscopy as anterior, lateral, or posterior. Catheter stability was verified by comparing pre- and post-RF amplitudes of local atrial potentials. The ablation site was ventricular in 52 patients (group A) and atrial in 10 (group B). In group A, 26 APs (50%) required a single RF current pulse for ablation. These APs showed no anatomic predilection and no statistically significant differences in electrogram parameters from 24 APs that were ablated only after a median of three pulses had failed, suggestive of a wider ventricular insertion of the latter APs. A lower A/V ratio and a higher incidence of transient AP block found in the remaining 2 group A patients, who had anteriorly located APs requiring > 10 failed pulses, suggested an adverse anatomy of the A-V groove in that region. A stepwise multivariate logistic regression analysis revealed that the simultaneous presence of (1) a presumed AP potential, (2) an A/V ratio > or = 0.10, (3) an A-V interval < or = 40 milliseconds, and (4) a delta-V interval < or = 0 milliseconds was associated with a specificity of 94% and a positive predictive accuracy of 87% for an RF pulse to be successfully applied to the ventricular insertion to the AP. Compared with APs of group A, APs of group B were distinguished by unsuccessful ventricular pulses associated with a delta-V interval > 10 milliseconds in the presence of an A/V ratio > 0.33 (specificity of 97% and positive predictive accuracy of 82%), which is suggestive of a more epicardial ventricular insertion of these APs. CONCLUSIONS: The effect of anatomic variations of the AP and the A-V groove is reflected in the bipolar endocardial electrogram and needs to be considered in the approach to AP ablation. The stepwise inclusion of the four electrogram criteria introduced in this study may improve the efficacy of RF catheter ablation of a manifest left free-wall AP at its ventricular insertion. Whenever mapping cannot improve on a delta-V interval > 10 milliseconds despite apparently close contact with the mitral annulus ("good" A/V ratio), attempts at ablation are likely to be successful at the atrial aspect of the mitral annulus.

Adult↗
PubMed1994

[Cardioversion in atrial fibrillation].

Atrial fibrillation is often not only associated with palpitations, but also with hemodynamic detoriation and high incidence of thromboembolic complications. However, since the establishment or maintenance of a sinus rhythm with antiarrhythmic drugs may also lead to an increased mortality, sinus rhythm should only be achieved by external electrical cardioversion and should be limited to those patients who have been shown to, or may be expected to markedly improved by this intervention. Internal electrical cardioversion should be restricted to those patients who fail external cardioversion. Implantable devices to automatically cardiovert atrial fibrillation are still under clinical investigation and will require further evaluation.

Atrial Fibrillation↗
PubMed1994

[The implantable cardioverter/defibrillator].

Despite all advances in the diagnosis and therapy of cardiovascular diseases, the mortality from malignant ventricular tachyarrhythmias is still a major health problem. In addition to established therapeutic strategies in the prevention of sudden cardiac death such as antiarrhythmic drug treatment, catheter ablation or antiarrhythmic drug treatment, cardioverter/defibrillator was introduced to clinical practice in 1980. The number of 50,000 overall implants reflects the current clinical status of the therapy with implantable cardioverter/defibrillators. Significant technical improvements in the defibrillator therapy may contribute to an increase in therapy acceptance. These advances include the introduction of nonthoracotomy lead systems, enhanced defibrillation efficacy, full programmable devices providing tiered electrical therapy, improved diagnostic Holter functions and enhanced arrhythmia detection algorithms. The major present goals of defibrillator therapy are detection and termination of malignant ventricular tachyarrhythmias, prevention of sudden cardiac death, reduction in patient's mortality and improvement in quality of life. The efficacy and safety of defibrillator therapy to prevent sudden arrhythmic death has been proven in several large clinical investigations In patients with this device the annual sudden cardiac death mortality is < 2% even in high-risk patient populations. Compared to sudden cardiac death rate there is a much higher rate of overall cardiac mortality because a defibrillator is not able to prevent nonarrhythmic cardiovascular deaths. There is a clinical impression that cardiovascular mortality is lower in patients treated with an implantable cardioverter/defibrillator compared to patients treated with other therapies. However, there are no results from controlled studies providing scientific evidence that defribillator therapy can decrease overall cardiovascular mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Death, Sudden, Cardiac↗
PubMed1993

Preliminary results of the Cardiac Arrest Study Hamburg (CASH). CASH Investigators.

Sodium channel blockers and class III antiarrhythmic compounds, as well as beta blockers, have been used in preventing recurrences of sudden cardiac death. In recent years, implantable cardioverter-defibrillators (ICDs) have been used increasingly, but no data from randomized trials comparing antiarrhythmic drug and ICD therapy have been reported in this setting. In 1987, the Cardiac Arrest Study Hamburg (CASH), a prospective, randomized trial, was initiated to compare metoprolol, amiodarone, propafenone, and ICD implantation in patients surviving sudden cardiac death due to documented ventricular tachycardia and/or ventricular fibrillation. The details of the study design and preliminary results are presented herein. The primary endpoint of the study is total mortality. The data reviewed in March 1992, representing a mean follow-up period of 11 months, indicated no significant differences among patients randomized to metoprolol, amiodarone, and ICDs. However, there was a significantly higher total mortality and cardiac arrest recurrence in patients randomized to propafenone compared with those randomized to the ICD treatment limb. The study continues with the deletion of the propafenone treatment limb.

Adult↗
PubMed1993

[The programming of the pulse amplitude: the effect on the longevity of cardiac pacemakers with high and low inhibition currents].

Recently developed rate-responsive cardiac pacemakers are smaller than conventional ones because of their smaller battery capacity. The influence of programming pulse amplitude on battery current was investigated in 13 patients (six women, seven men; mean age 66 +/- 11 years), seven with a small pacemaker (1.2 Ah battery capacity) and six with a conventional model (1.65 Ah battery capacity), 3-12 months after pacemaker implantation. The telemetrically measured battery current of the conventional pacemaker was significantly greater than that of the smaller one. While stimulation currents were the same, the conventional model had a higher inhibition current (22 +/- 0 microA) than the rate-responsive one (7.1 +/- 0.1 microA). At 5 V impulse amplitude the calculated period of functioning was 5.8 years for the conventional pacemaker and 8.2 years for the rate-responsive one. Programming for 2.5 V increased the calculated period of functioning by 1.5 for the conventional and by 5.1 years for the rate-responsive pacemaker. The smaller, rate-responsive pacemaker thus has a longer period of functioning, at least 7 years, because of its superior circuitry. By programming the impulse amplitude at 2.5 V the period is increased to more than 10 years.

Aged↗
PubMed1993

Loss of "pacemaker's identity" following activation of the emergency VVI feature.

Electromagnetic signals coming from the pacemaker programmer can permanently damage multiprogrammable pacemakers. At a follow-up of a sixfold programmable VVI pacemaker (Phoenix 251-6, Pacesetter), the emergency VVI button was activated on the programmer after the programming of the pacing impulse had induced a loss of capture. The next telemetrical interrogation revealed an alteration to a threefold programmable Programmalith III. The inadvertent programming of the model number occurred, because the programming head was removed at one very specific time in the programming sequence of the emergency VVI command.

Aged↗