Search PubMed⌕ Search

Biomedical subjects

K H Kuck

Publications and source records attributed to K H Kuck.

At least 91 records · Page 5Linked to original sources
PubMed1993

First lessons from radiofrequency catheter ablation in patients with ventricular tachycardia.

UNLABELLED: Fourteen patients (12 men, 2 women; 61 +/- 9 years) with ventricular tachycardia and underlying heart disease underwent an attempt at radiofrequency energy catheter ablation. Twelve patients had coronary disease and two patients had dilated cardiomyopathy. Two patients had two clinical tachycardias, the ejection fraction was 38% +/- 11%. All tachycardias were inducible and hemodynamically well tolerated (cycle length = 357 +/- 56 msec). Ablation was initially successful in nine patients (no tachycardia inducible after ablation and before discharge). Two patients had recurrences (in-hospital and 4 months) and one patient had a tachycardia of a different morphology, which was also successfully ablated. Ablation was overall successful in seven patients and unsuccessful in seven patients (including all patients with cardiomyopathy). Mid-diastolic potentials were observed in all the patients in whom ablation was successful but not observed in four of seven unsuccessful patients. The successful patients remain free of recurrences at 9 +/- 8 months follow-up. CONCLUSIONS: (1) in ventricular tachycardia following an old infarction radiofrequency energy ablation is possible with a high success rate if a critical component of the tachycardia circuit can be localized. Localizing isolated mid-diastolic potentials and ensuring these potentials are part of the reentrant circuit with concealed entrainment can help to enhance the results. (2) A negative predischarge electrophysiological study may be predictive of success.

Cardiac Pacing, Artificial↗
PubMed1993

Radiofrequency current catheter ablation for control of supraventricular arrhythmias.

With the advent of radiofrequency energy, catheter ablation techniques have become an accepted form of treatment for a variety of supraventricular arrhythmias. The ablation of the atrioventricular (AV) node was performed first and is now widely used in patients with refractory atrial fibrillation or flutter. Ablation has also replaced surgery in patients with preexcitation syndromes, and as the complication rate in experienced centers is low, it has become the first line of treatment in these institutions. The results of catheter ablation in AV nodal reentrant tachycardia are excellent as well, although there is still debate about whether "slow" pathway ablation is superior to "fast" pathway ablation. Radiofrequency current ablation has also contributed to a better understanding of the pathophysiology of AV nodal reentrant tachycardia, as it has provided evidence for atrial participation in the reentrant circuit. Experience with atrial tachycardias and tachycardias due to Mahaim fibers remains limited. The ideal source of energy for specific arrhythmias is still unknown and improvement in catheter technology is needed.

Atrioventricular Node↗
PubMed1993

Effects of local steroid elution on chronic pacing threshold and impedance of endocardial pacemaker leads.

To study the effects of steroid elution on chronic pacing threshold and impedance, a 4-mm2 surface area lead with steroid (030-368, Telectronics; n = 9) was compared to the same lead without steroid (030-359, Telectronics; n = 9) 3 months after implantation. The pulse duration thresholds of the steroid lead were significantly lower at 0.8, 1.6, 2.5, and 5.0 V. Impedance measured by telemetry at 0.8, 1.6, 2.5, 5.0 and 8.0 V pulse amplitude, and 0.05, 0.25, 0.5 and 1.0 ms pulse duration was similar for the two leads. Mean impedance was about 650 omega and did not change from 0.8 to 8.0 V. The local steroid elution reduced the pacing threshold, but had no influence on the impedance. The stable impedance indicates that the impedance of this lead was not modified by pulse-dependent variables and, therefore, can also be correctly determined at pulse amplitudes below 5.0 V.

Aged↗
PubMed1993

[Outpatient diuretic treatment of terminal heart failure by a completely implantable venous infusion system].

In severe heart failure with peripheral and enterohepatic congestion resistance to diuretics with inactivation of oral furosemide is a common finding. Impaired bioavailability is most likely related to pharmacodynamic and especially to pharmacokinetic reasons. To ensure efficient drug delivery and effective treatment with diuretics, venous access devices (port-systems) were implanted in 10 patients (eight men and two women, age between 57 and 80 years). All patients were in heart failure functional class III-IV and had a history of recurrent episodes of severe decompensation; none was suitable for heart transplantation. Injections of furosemide and other drugs were performed 1-4 times a day; one female patient performed the intravenous injections herself, in three cases the partners and in six cases the practitioner or an outpatient nurse performed the injections. All patients were treated on an outpatient basis, i.e., at home or in nursing homes. The port-implantation was followed up between 30 and 742 days (1-24 months); no serious complications were observed. Both patients and their partners were considered to well tolerate and accept the port-systems. Totally implantable venous access devices promise to reduce the number and severeness of cardiac decompensations in chronic preterminal heart failure by application of daily intravenous furosemide. This form of outpatient treatment will ameliorate the quality of life and stabilize the course of these severely and chronically ill patients.

Aged↗
PubMed1993

[The predictors of success in the radiofrequency ablation of left accessory pathways using the single-catheter technic].

INTRODUCTION AND OBJECTIVES: To determine the predictors of successful radiofrequency current ablation of an accessory pathway using the single-catheter approach, we retrospectively analyzed 46 consecutive patients with left sided accessory atrioventricular pathways and manifest preexcitation. METHODS: Ablation using a single catheter advanced retrogradely towards the mitral valve was successful in 42 (91%). A radiofrequency pulse resulting in permanent accessory pathway block was defined as a successful pulse; a pulse that had no effect or caused only transient accessory pathway block was defined as an unsuccessful pulse. RESULTS: Successful radiofrequency pulses (n = 37) did not differ from those that failed (n = 56) in the local atrium-accessory pathway potential interval, in the accessory pathway-ventricle interval nor in the cumulative energy delivered. But in successful radiofrequency pulses, the amplitude ratio of local atrium and ventricular potentials tended to be larger (0.29 +/- 0.17 vs 0.23 +/- 0.17; p = 0.053) and presumed accessory pathway potential was more often recorded (36 [97%] vs 38 [68%]; p = 0.006). The time elapsed from the beginning of the current application and the accessory pathway block was shorter in successful pulses as compared to those pulses producing only transient block (3.3 +/- 2 s vs 6.9 +/- 4 s). CONCLUSIONS: The recording of a presumed accessory pathway potential, a large local A/V ratio and the occurrence of early conduction block in the accessory pathway were the best predictors of successful radiofrequency current application using the single-catheter approach.

Adolescent↗
PubMed1993

[Low energy cardioversion with the implantable cardioversion defibrillator devices for treatment of ventricular tachycardia and ventricular fibrillation].

Programmable implantable cardioverter-defibrillators (ICD) with low energy capabilities for the treatment of ventricular tachycardia were introduced to increase patients acceptance and lengthen battery life. However, no data about efficacy and safety of low energy cardioversion with subsequent defibrillation in ventricular tachycardia and fibrillation are available. Nineteen of 42 patients with documented or inducible ventricular tachycardia before ICD implantation were studied. In all patients the effectiveness of low-energy cardioversion (< or = 4 joules) with subsequent high-energy defibrillation was evaluated in monomorphic ventricular tachycardia and/or ventricular fibrillation. During predischarge programmed stimulation in 13/19 patients, a total of 32 monomorphic ventricular tachycardias occurred, and in only six patients could ventricular fibrillation be induced. A tachycardia-related efficacy of 69% and patient-related efficacy of 46% of the low-energy cardioversion < or = 4 joules was observed. Ten tachycardias were accelerated to ventricular fibrillation or remained unchanged (n = 2). The second shock (energy > 17 joules) terminated seven arrhythmias, whereas a third (30 joules) shock or an external defibrillation (n = 2) was necessary for termination of the remaining three arrhythmias. After induction of ventricular fibrillation as the primary arrhythmia, the first (low-energy) shock terminated 2/16 episodes, whereas the second (high-energy) shock reverted ventricular fibrillation in 11/16 episodes. In one patient, a second high energy shock and in two patients external defibrillation was necessary for conversion of ventricular fibrillation. In one patient, an increase of the defibrillation threshold induced by amiodarone could be identified.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

[Syncope in supraventricular tachycardia. Incidence, pathomechanism and consequences].

Syncope occurs in up to 20% of patients with supraventricular tachycardias and is suggestive of rapid and dangerous arrhythmias. Incidence, pathomechanism and consequences of syncope in supraventricular tachycardia are reviewed in this presentation. Frequent symptoms in supraventricular tachycardias are palpitations, dizziness or dyspnea. Syncope is more uncommon, however, if a sensation of rapid heart beat precedes a syncope, a causal relationship between arrhythmia and syncope has to be considered. When the surface ECG shows no abnormalities, Holter monitoring or exercise testing usually fail to record a suspected tachycardia, therefore, electrophysiologic study should be performed to verify the underlying arrhythmia. In patients with unexplained syncope supraventricular arrhythmias can be established in up to 15% of patients. However, interpretation of electrophysiologic results has to be performed carefully because functional abnormalities like dual AV nodal pathways can be found in up to 10% of asymptomatic patients. The prognostic value of syncope as a marker for rapid tachycardia or sudden cardiac death is still in discussion. Syncope in patients with Wolff-Parkinson-White syndrome may help to identify patients at risk for ventricular fibrillation due to rapid conduction over an atrioventricular accessory pathway during atrial fibrillation. Syncope in young patients (< 25 years) with Wolff-Parkinson-White syndrome was found to be associated with a short anterograde refractory period (< 220 ms) of the pathway. However, most of the studies were performed retrospectively in selected patients referred to the centers because of severe symptoms, therefore the predictive value of syncope in unselected patients with supraventricular tachycardia remains uncertain.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrioventricular Node↗
PubMed1993

[Shortening the stimulus T time: indicator for physical activity in patients with demand modulated cardiac pacemakers].

Activity-modulated pacemakers detect body vibrations and increase their pacing rate. As the body vibrations are not always related to physical activity, we studied in 20 patients with the activity-modulated pacemaker Legend (Medtronic) whether a second physiological signal, the paced QT duration, can help to verify exercise. At rest, pacing rate was programmed from 60 ppm to 130 ppm in steps of 10 ppm which shortened the QT duration from 467 +/- 32 ms (60 ppm) to 391 +/- 24 ms (130 ppm). During treadmill exercise, pacing rate increased from 62 +/- 1 ppm to 98 +/- 9 ppm and the QT duration decreased from 450 +/- 25 ms to 372 +/- 27 ms. Compared to rest, the exercise-induced QT shortening was significantly shorter for pacing rates > or = 70 ppm. To simulate artificial sensor activation, an electrical razor was put onto the pulse generator. Pacing rate increased to 81 +/- 7 ppm, but the QT duration shortening was similar to the measurement at rest with 80 ppm. In conclusion, the paced QT duration is able to confirm whether body vibrations are related to physical exercise.

Adult↗
PubMed1993

[Atrial fibrillation in Wolff-Parkinson-White syndrome. Development and therapy].

In patients with Wolff-Parkinson-White syndrome the accessory pathway may participate in various tachyarrhythmias thereby influencing symptoms and prognosis. Atrial fibrillation occurs in 10 to 32% of patients and may have life-threatening consequences by precipitating ventricular fibrillation in patients with rapid conduction due to an accessory pathway with short anterograde refractory period (< 250 ms). Pathogenesis of atrial fibrillation in the WPW syndrome and therapeutic options are reviewed in this presentation. Spontaneous degeneration of atrioventricular reentrant tachycardia has been reported to represent the most frequent mode of initiation of atrial fibrillation during electrophysiologic study (up to 64% of episodes). Hemodynamic changes during tachycardia may lead to increased sympathetic tone, hypoxemia or increased tension of the atrial wall, thus, triggering atrial fibrillation. Induction of reentrant tachycardia during electrophysiologic study also has shown to be strongly correlated to its clinical prevalence and is inducible in up to 77% of patients with atrial fibrillation. The pathogenesis and high incidence of atrial fibrillation in patients with WPW syndrome is related to presence and functional properties of the accessory pathway. After surgical excision or catheter ablation more than 90% of patients are free of this arrhythmia. Anterograde conduction properties of the pathway appear to be more important than retrograde properties. High incidence of atrial fibrillation is related to short anterograde refractory periods, and of note, this arrhythmia is rare (3%) in patients with concealed pathways. With intracardiac recordings, Jackman et al. could demonstrate atrial fibrillation due to micro-reentry originating in accessory pathway networks.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Fibrillation↗
PubMed1993

[Stable stimulation impedance of steroid electrodes in various impulse amplitudes: indications for low polarization of the electrode-myocardium interface].

The reduction of electrode surface area leads to an increase of pacing impedance which may be caused either by higher tissue resistance or by greater polarization occurring at the electrode-myocardium interface. The impedance of steroid-eluting leads with both 8 mm2 surface area (CapSure 4003, Medtronic n = 12) and with 4 mm2 (030-368, Telectronics, n = 8) were compared to the impedance of a high polarizing Elgiloy lead (PE 60/4 DN, Biotronik; n = 7). All leads were connected to the same unipolar VVI pacemaker (Pasys 8329, Medtronic). Pacing impedance was measured at 0.8, 1.6, 2.5, 5.0, and 8.0 volts pulse amplitude and at 0.05, 0.25, 0.5, 1.0, 2.0 msec pulse duration. Impedance of the Elgiloy lead was constant at 0.05 and 0.25 msec, but increased at longer pulse durations for pulse amplitudes below 5.0 volts. Both steroid-eluting leads had constant impedance at each pulse duration. The impedance of the 4 mm2 lead was significantly higher than of the 8 mm2 lead. In contrast to the Elgiloy lead, impedance of the steroid-eluting leads is not influenced by pulse-dependent factors such as polarization, indicating that the higher impedance of the 4 mm2 steroid-eluting lead is caused by a higher tissue resistance and not by greater polarization.

Aged↗
PubMed1992

[Floating intracardiac metastasis].

Two years after the removal of an embryonic testicular tumour from a now 26-year-old man, his general health deteriorated and a holosystolic murmur was heard over the tricuspid valve area. A chest X-ray film demonstrated lung metastases. Biochemical tests were within normal limits, but the human chorionic gonadotrophin level was elevated to 81,030 mU/ml. Echocardiography revealed mild tricuspid regurgitation and a floating mass between the right atrium and ventricle, in contact with the tricuspid valve. The described findings did not support the diagnosis of embolus or inflammatory vegetation. Because of the danger of embolization and obstruction of the pulmonary outflow tract the mass was removed surgically. Enzyme-histological examination identified the tissue as a metastasis of the testicular tumour. The patient's condition at first improved, but he soon died of bleeding from the lung which was infiltrated by trophoblast-containing metastases of the testicular tumour.

Adult↗
PubMed1992

[Local steroid elution via pacemaker electrodes: improved stimulation and sensing functions].

The effect of local elution of dexamethasone on stimulation and sensing properties of pacemaker electrodes was studied in 20 patients with cardiac arrhythmias (11 men, 9 women; average age 73 +/- 9 years). In two randomized groups of 10 patients each a unipolar ventricular electrode (surface area 4 mm) with or without steroid was implanted. The steroid electrode contained 0.5 mg dexamethasone which elutes into the surrounding myocardium from a silicon ring at the electrode tip. Stimulation threshold was determined at 0.05 ms to 1.5 ms impulse duration in 0.8 V steps, impedance being measured by telemetry. Correct R wave sensing was tested for 1.25, 2.5 and 5.0 mV. While stimulation thresholds after implantation of an electrode without steroid rose to a maximum after two weeks, there was only a mild rise in threshold within the first week after implantation of a steroid electrode, the threshold then remaining constant. In none of the patients did the stimulation threshold rise above 0.8 V at an impulse duration of 0.5 ms. The intracardiac signal at 5.0 mV sensitivity was correctly sensed in all 10 patients with a steroid electrode, but in only 7 without steroid. A further reduction in stimulation energy over that with a standard impedance of 500 ohm was achieved at impedances greater than 600 ohm.

Aged↗
PubMed1992

Catheter ablation from right atrium of anteroseptal accessory pathways using radiofrequency current.

Catheter ablation with radiofrequency current has recently been introduced as a therapeutic regimen for symptomatic patients with the Wolff-Parkinson-White syndrome or atrioventricular (AV) tachycardia mediated by a retrogradely conducting (concealed) accessory AV pathway. These pathways may be located, although infrequently, in the anteroseptal region of the heart in close proximity to the AV node-His bundle conduction system. Any attempt to interrupt an anteroseptal accessory pathway therefore is subject to the potential complication of inadvertent impairment of normal AV conduction. This study was conducted to establish whether abolition of anteroseptal accessory pathways by radiofrequency current aimed at the atrial as opposed to the ventricular insertion of the pathway can be achieved with preservation of AV node-His bundle conduction. Twelve patients (mean age 37 +/- 13 years; 10 with Wolff-Parkinson-White syndrome, 2 with a concealed accessory pathway) were studied. In the majority of patients, radiofrequency current (500 kHz; mean energy 577 +/- 207 J) was applied through a steerable catheter with a long tip electrode placed in the anterior septal space at the atrial aspect of the tricuspid anulus, with the intention to destroy the atrial insertion of the accessory pathway. All pathways were successfully ablated. The AV node or His bundle conduction was not impaired in any patient. Right bundle branch block was induced in two patients (17%). There were no complications related to the procedure. It is concluded that catheter ablation from the right atrium using radiofrequency current provides effective and safe interruption of anteroseptal accessory pathways with good preservation of the normal conduction system.

Adult↗