Unexplained cardiac arrest. The need for a prospective registry.
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K H Kuck
Publications and source records attributed to K H Kuck.
Preservation of atrioventricular nodal conduction during radiofrequency current catheter ablation of midseptal accessory pathways.
BACKGROUND: Septal accessory atrioventricular (AV) pathways may be located in close vicinity of the His bundle-AV nodal conduction system. Attempts at surgical or electrical interruption of these pathways may therefore result in impairment of normal AV conduction. This study focuses on a subset of septal pathways with an atrial insertion located inside the triangle of Koch. In this study, they were called "midseptal." METHODS AND RESULTS: Six patients with a midseptal accessory pathway (mean +/- SD age, 40 +/- 12 years; five with Wolff-Parkinson-White syndrome and one with a concealed accessory pathway) underwent attempts at ablation of their pathway using 500-kHz radiofrequency current applied to the atrial insertion of the accessory connection. Guided by the recording of accessory pathway activation potentials, the ablation catheter was positioned in all patients in an area bounded anteriorly by the tip electrode of the His bundle catheter and posteriorly by the coronary sinus ostium. All pathways were successfully ablated without the induction of complete heart block. First-degree AV conduction block occurred in one patient in whom a concealed accessory connection was located closer to the AV node than to the coronary sinus ostium. CONCLUSIONS: Radiofrequency current catheter ablation may be used effectively for midseptal accessory pathways and should be preferred in experienced centers as a safe alternative to surgical therapy.
Adult↗
[Value of experimental and clinical methods on the effectiveness and side effect profile of anti-arrhythmia agents].
The suppression by antiarrhythmic drugs of ventricular premature beats, pairs and salvos is frequently not associated with a suppression of ventricular tachycardia or fibrillation in the same patient. The evaluation of antiarrhythmic drugs must therefore distinguish between antiectopic, anti-reentry and anti-fibrillatory efficacy. Clinical methods such as Holter monitoring and programmed electrical stimulation which only allow the validation of anti-ectopic or anti-reentry efficacy present a major problem in the evaluation of antiarrhythmic drugs. Anti-fibrillatory drug efficacy cannot be evaluated by clinical methods.
Anti-Arrhythmia Agents↗
Radiofrequency catheter ablation of accessory pathways.
One hundred five patients with an accessory atrioventricular pathway underwent catheter ablation of the pathway using radiofrequency current. There were 79 accessory pathways located on the left and 32 on the right side of the heart. In patients with right-sided pathways ablation was attempted via a catheter positioned at the atrial aspect of the tricuspid annulus. In patients with a left-sided free-wall accessory pathway a novel approach was utilized in which the ablation catheter was positioned in the left ventricle directly below the mitral annulus. Accessory pathway conduction was permanently abolished in 93 patients (89%). Failures were mainly due to inadequate catheters used initially. It is concluded that catheter ablation of accessory atrioventricular pathways using radiofrequency current is an effective and safe therapeutic modality for patients with symptomatic tachyarrhythmias mediated by these pathways.
Adult↗
[Successful high-frequency current ablation of three accessory conduction pathways in a single session].
A case is presented of a 25-year-old symptomatic male with Wolff-Parkinson-White syndrome and three overt accessory atrioventricular connections which were all diagnosed and ablated during the same session. A discordant preexcitation pattern between delta wave and QRS axis was found on the surface electrocardiogram, indicating the presence of two or more accessory pathways. During atrial pacing the appearance of a changing QRS morphology and alternating delta wave suggested the presence of an additional left-sided pathway. After ablation of a right anteroseptal pathway, a second pathway was found located in the left lateral position and was successfully ablated. The final pathway became evident only after the ablation of the first two and was found to be located in a right midseptal position. This pathway was also ablated during this session. There were no complications and the patient remained asymptomatic during an 11-month follow-up.
Adult↗
[Prospective long-term ECG study of 100 patients surviving sudden cardiac death].
One hundred survivors of sudden death were randomized to four groups and treated with Amiodarone, Propafenone and Metoprolol, or were supplied with an automatic implantable cardioverter/defibrillator (AICD, control group). Prospective Holter-monitoring showed that the prognostic significance of the complexity and frequency of ventricular ectopic activity in survivors of sudden cardiac death is relative to the chosen prophylactic antiarrhythmic treatment: Findings in the control group confirm the classical notion that frequent and complex ventricular ectopic activity is predictive for recurrent life-threatening ventricular tachyarrhythmias (relapse) (> or = 25 VES/h, p < 0.05; Lown IVb, just short of statistical significance). Therapy with Amiodarone reduced frequent and complex ventricular ectopic activity as well as the 2-year relapse rate, which was significantly lower than in the control group (AICD: 36%, Amiodarone 12%, p = 0.03). Under Metoprolol the frequency and complexity of ectopic ventricular activity increased, yet the relapse rate was reduced (12%, p = 0.03). Under Propafenone, especially, those patients who showed low frequencies of ventricular ectopic activity were at high risk; the 2-year relapse rate was 28%.
Adult↗
Radiofrequency current for catheter ablation of accessory atrioventricular connections in children and adolescents. Emphasis on the single-catheter technique.
Catheter ablation of an accessory atrioventricular connection using 500-kHz radiofrequency current was attempted in 10 children and adolescents aged between 6 and 15 years (mean 10.5 years). Six children had the Wolff-Parkinson-White syndrome and four had tachyarrhythmias related to a retrograde-only conducting ("concealed") accessory connection. No child had associated structural heart disease. Symptoms ranged from disabling palpitations to episodes of syncope (three patients) and cardiac arrest (one patient). Ablation was attempted from the left ventricle in all children; in one child, ablation of a second, right-sided pathway was attempted via a right atrial approach. Ten of the 11 accessory connections were interrupted successfully. A single complication was encountered in a 10-year-old girl in whom the procedure had to be terminated because a thrombotic occlusion of the right internal iliac artery had evolved. A simplification of the ablation procedure associated with reduced procedure duration and radiation exposure time was achieved in three children with the Wolff-Parkinson-White syndrome and a left free-wall accessory pathway when a single catheter placed in the left ventricle was used for pathway localization as well as ablation. It is concluded that catheter ablation using radiofrequency current is effective and safe and may supersede surgery as the curative treatment for children with serious symptoms mediated by an accessory atrioventricular connection.
Atrioventricular Node↗
[Catheter ablation of septal accessory conduction pathways with high frequency electric current].
In 58 symptomatic patients with septal accessory atrioventricular pathways, attempts at catheter ablation of the pathway were made using 500-kHz radiofrequency current. The methodological approach (introduction and final positioning of the ablation catheter) was dependent on the anatomical site of the accessory pathway. Right anteroseptal pathways were accessed via a jugular venous route, whereas a femoral venous route was used for right mid- and posteroseptal pathways. In these pathways, ablation was attempted from an atrial catheter position. Left posteroseptal pathways were located via mapping of the coronary sinus and were ablated either from the left ventricle or (in 3 cases) from the vena cordis media. Utilizing a deflectable catheter with a 4-mm tip electrode, ablation attempts were successful in 54 patients (93%) with a median of 12 radiofrequency current pulses of an average 24.9 W of power and 23.2 s length. The mean duration of the sessions was 4.6 h. Impairment of physiological conduction (first-degree AV block) was observed in 1 patient; complete heart block was never induced. Recurrences after initially successful ablation necessitated a repeat session in 2 patients. One patient died 3 days after successful ablation of a posteroseptal accessory pathway. Septal accessory pathways may be ablated using radiofrequency current with an efficacy and safety comparable to free-wall accessory pathways and with good preservation of physiological AV node-His bundle conduction.
Adolescent↗
Current status of radiofrequency ablation in the preexcitation syndromes.
Catheter ablation techniques have become an accepted treatment form for a variety of supraventricular arrhythmias. After the introduction of radiofrequency energy, catheter ablation has become the first line of treatment and has replaced surgery in patients with the preexcitation syndromes. The success rate in large series is very high, while the complication rate in experienced hands is very low. Despite all this progress, the ablation of a small subset of accessory atrioventricular pathways poses some problems. The ideal source of energy is still unknown and improvement in catheter technology are needed. This review will try to focus on some of these issues dealing with a very exciting area of clinical cardiology.
Cardiac Catheterization↗
Radiofrequency current catheter ablation of accessory atrioventricular pathways.
Tachyarrhythmias mediated by an accessory atrioventricular pathway and which are refractory to drug therapy have been treated surgically with variable success. Early results of direct-current catheter ablation were encouraging but were associated with complications such as barotrauma and the need for a general anaesthetic. We have investigated the endocardial application of radiofrequency current which is a potentially safer technique. Of 105 patients with an accessory atrioventricular pathway, 79 were located on the left side of the heart and 32 on the right side. Accessory pathway conduction was permanently abolished in 93 (89%) patients. Complications developed in 3 patients: thrombotic occlusion of a femoral artery, arteriovenous fistula formation at the site of groin puncture, and left ventricular rupture with cardiac tamponade after direct-current shocks. There were no deaths from the procedure. We conclude that radiofrequency current catheter ablation is both effective and safe for patients with symptomatic tachyarrhythmias mediated by accessory atrioventricular pathways.
Adult↗
Intravenous dantrolene does not exhibit calcium channel blocking effects on the cardiac conduction system in humans.
In malignant hyperthermia, dantrolene, a drug assumed to possess calcium channel blocking properties, effectively suppresses supraventricular and ventricular arrhythmias. To investigate antiarrhythmic properties of dantrolene, six patients (three women and three men, age 42 +/- 18 yr) with symptomatic atrioventricular (AV)-nodal reentry tachycardia were studied. Electrocardiographic measurements included sinus cycle length, PQ-interval, width of the QRS-complex, and QT- and rate-corrected QT-interval. During the electrophysiologic study, effective refractory periods of the right atrium, AV node, right ventricle, and AV-nodal conduction intervals were determined, and AV-nodal reentry tachycardia was induced in all patients. Dantrolene was administered intravenously over a period of 15 min at doses of 1.0, 1.5, or 3.0 mg/kg in two patients each. The dosage was not further increased because of side effects at the dose of 3.0 mg/kg. After the infusion of dantrolene, the electrocardiographic measurements and electrophysiologic study were repeated. The plasma concentrations of dantrolene ranged from 1.69 to 6.61 micrograms/ml at the time of the electrophysiologic study. After dantrolene administration, the sinus cycle length shortened from 686 +/- 80 to 622 +/- 55 ms (P less than 0.05). No significant changes of any other parameter could be demonstrated after intravenous dantrolene. AV-nodal reentry tachycardia remained inducible in all patients without change of the tachycardia cycle length and without change in coupling intervals of tachycardia-inducing extrastimuli. Antiarrhythmic properties of dantrolene could not be demonstrated in patients with AV-nodal reentry tachycardia at therapeutic doses.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Effects of body constitution and age on maximum pacing rate of activity-modulated rate responsive pacemakers.
UNLABELLED: The pacing rate of activity-modulated pacemakers is triggered by vibrations running through the body. Whether the body constitution predicts maximum pacing rate and may facilitate rate response programming was studied in 16 patients with Activitrax pacemakers. Rate response parameters were programmed to a fixed setting in VVIR/VOOR mode (lower pacing rate 60 ppm, upper pacing rate 125-130 ppm, activity threshold medium/7). Body vibrations were induced by a treadmill exercise test with increasing speed. Maximum pacing rates were measured at the stage of symptom-limited tolerance. Exercise tests with a duration of 7.3 +/- 2.9 minutes resulted in a maximum pacing rate of 98 +/- 22 ppm ranging from 60-122 ppm. Maximum pacing rates did not differ between male (n = 10; 102 +/- 21 ppm) and female (n = 6; 92 +/- 24 ppm). Correlations between maximum pacing rates and body constitutional factors were not significant with r = -0.15 (weight), r = 0.39 (height), r = 0.07 (body surface area), and r = -0.27 (skin-fold thickness). The correlations with body mass index (r = -0.53) and age (r = -0.53) were initially significant, but not after Bonferroni-Simes-Hommel correction. The age-dependent relationship may be caused by the shorter exercise duration of older patients indicated by the correlation between exercise duration and maximum pacing rate (r = 0.77), as well as with age (r = -0.73). CONCLUSIONS: body constitution did not modify body vibrations and did not allow prediction of maximum pacing rates; therefore, it is no aid for the programming of rate response parameters.
Aging↗
Successful catheter ablation of human ventricular tachycardia with radiofrequency current guided by an endocardial map of the area of slow conduction.
A case is presented of a 68-year-old male patient with a history of myocardial infarction and recurrent ventricular tachycardia who was successfully treated with a single 20-second transcatheter application of radiofrequency current. Prior to current application a complete endocardial map had been obtained of an area of slow conduction that extended caudo-cranially for approximately 2 cm along the lower left ventricular septum. Stimulation techniques yielded evidence that this area was critically related to tachycardia initiation and maintenance. Its central part was subsequently chosen as the site for current delivery.
Aged↗
Benefits of smaller electrode surface area (4 mm2) on steroid-eluting leads.
The purpose was to test whether a reduction of pacemaker electrode surface area below 8 mm2 improves leads that elute steroid from the electrode tip to the surrounding myocardium. A standard-sized 8 mm2 lead with 1 mg dexamethasone was implanted in 12 patients and a lead with 4 mm2 electrode surface area and 0.5 mg dexamethasone in ten patients. Pacing threshold, impedance, and sensing threshold were measured at implantation and after 1, 4, and 12 weeks. Pacing thresholds were similar for both groups and were always less than or equal to 0.8 V at 0.5 msec pulse duration in all patients. Impedance was significantly higher (P less than 0.05) for the 4 mm2 lead (implantation: 726 +/- 119 ohms; 1 week: 596 +/- 71 ohms; 4 weeks: 624 +/- 68 ohms; 12 weeks: 643 +/- 56 ohms) than for the 8 mm2 lead (implantation: 422 +/- 43 ohms; 1 week: 402 +/- 48 ohms; 4 weeks: 439 +/- 57 ohms; 12 weeks: 449 +/- 61 ohms). R wave amplitudes did not differ between both groups; no sensing failure occurred at 5 mV sensitivity. Compared to the 8 mm2 lead the reduction of surface area to 4 mm2 did not influence pacing threshold, but resulted in a higher pacing impedance. The amount of pacing energy was lower in the smaller-sized electrode. For clinical impact, low pacing threshold and high impedance leads are the condition to implant pulse generators with smaller battery capacity.
Aged↗
Catheter ablation of atrioventricular junction using radiofrequency current in 17 patients. Comparison of standard and large-tip catheter electrodes.
BACKGROUND: Two catheter electrode systems were compared for delivering radiofrequency current for ablation of the atrioventricular junction. Seventeen patients with drug-resistant supraventricular tachyarrhythmias were studied. METHODS AND RESULTS: A 6F or 7F catheter with six or eight standard electrodes (1.25 mm wide, 2.5-mm spacing) was used in the first seven patients (group 1). A 7F quadripolar catheter with a large-tip electrode (4 mm long; surface area, 27 mm2) was used in the final 10 patients (group 2). Both ablation catheters were positioned to record a large atrial potential and a small but sharp His bundle potential from the distal bipolar electrode pair. Radiofrequency current was applied between a large skin electrode on the left posterior chest and either 1) each individual electrode on the standard-tip electrode catheter at 40 V (group 1) or 2) the large-tip electrode at 50-60 V (group 2). Radiofrequency current was limited to 40 V in group patients because of the strong potential for an early impedance rise when higher voltage is applied through standard electrodes. Complete atrioventricular block was achieved in six of seven group 1 patients and all 10 group 2 patients. A junctional escape rhythm followed ablation in five or six group 1 patients (mean cycle length, 1,066 +/- 162 msec) and eight of 10 group 2 patients (mean cycle length, 1,281 +/- 231 msec). Atrioventricular block was produced in a mean of 4.7 +/- 4.6 radiofrequency current applications delivered over a period of 42 +/- 45 minutes using the large-tip electrode (group 2) compared with 46 +/- 22 applications using standard electrodes (15.9 +/- 10.2 applications delivered through the standard-tip electrode) over a period of 147 +/- 59 minutes (group 1). For the application producing atrioventricular block, the large-tip electrode used higher voltage (58 +/- 17 versus 38 +/- 5 V, p less than 0.03) and had lower impedance (103 +/- 22 versus 148 +/- 40 omega, p less than 0.01), resulting in greater power (33.0 +/- 13.0 versus 10.2 +/- 0.6 W, p less than 0.003) and shorter time to block (8 +/- 3 versus 22 +/- 3 seconds, p less than 0.001). Current delivery through standard electrodes was limited by an impedance rise occurring 7 +/- 7 seconds after the onset of one or more radiofrequency current applications at 10 +/- 1 W in six of seven patients. Using the large-tip electrode, an impedance rise occurred in five of 10 patients, but at 25 +/- 10 W and after 21 +/- 9 seconds. Atrioventricular block occurred before the impedance rise in three of these five patients. Complete atrioventricular block persisted in 15 of 16 patients at a mean follow-up of 8.7 months. Atrioventricular conduction returned at 1 month in one group 2 patient and was successfully ablated by a second procedure. Three group 1 patients died 0.5-2 months after ablation, and a fourth patient underwent cardiac transplantation after 10 months. Pathological examination of the heart in two of these patients showed necrosis of the atrioventricular node and origin of the His bundle, without injury to the middle or distal His bundle. All 10 group 2 patients are alive and subjectively improved after ablation. CONCLUSIONS: We conclude that catheter-delivered radiofrequency current effectively produces complete atrioventricular block (94%) without requiring general anesthesia or the risk of ventricular dysfunction or cardiac perforation. The large-tip electrode allows a threefold increase in delivered power and markedly decreases the number of pulses and time required to produce atrioventricular block.
Atrioventricular Node↗
Catheter ablation using radiofrequency current to cure symptomatic patients with tachyarrhythmias related to an accessory atrioventricular pathway.
BACKGROUND: Recent investigations have shown that cure of patients with symptomatic tachyarrhythmias related to an accessory atrioventricular pathway may be achieved by closed-chest electrode catheter ablation of the accessory connection. Direct current shocks have primarily been used for this purpose, but its applicability is limited because of the lack of controlled titration of electrical energy, the infliction of barotrauma, and the need for general anesthesia. Radiofrequency current has been proposed as an alternate energy source. METHODS AND RESULTS: Seventy-three symptomatic patients with Wolff-Parkinson-White syndrome and 19 patients with only retrogradely conducting (concealed) pathways underwent ablative therapy with radiofrequency current. There were 71 accessory pathways located on the left side of the heart (57 free-wall and 14 posteroseptal pathways) and 25 on the right side (11 free-wall, seven posteroseptal, and seven midseptal or anteroseptal pathways). In patients with right-sided pathways, ablation was attempted via a catheter positioned at the atrial aspect of the tricuspid annulus. In patients with a left-sided free-wall accessory pathway, a novel approach was used in which the ablation catheter was positioned in the left ventricle directly below the mitral annulus. Accessory pathway conduction was permanently abolished in 79 patients (86%). Growing experience and improved catheter technology resulted in a 100% success rate after the 52nd consecutive patient. Failures were mainly the result of inadequate catheters used initially or an unfavorable approach to left posteroseptal pathways. CONCLUSIONS: Catheter ablation of accessory atrioventricular pathways by the use of radiofrequency current is an effective and safe therapeutic modality for patients with symptomatic tachyarrhythmias mediated by these pathways.
Adult↗
Single-catheter approach to radiofrequency current ablation of left-sided accessory pathways in patients with Wolff-Parkinson-White syndrome.
BACKGROUND: Catheter ablation with the use of radiofrequency current has been introduced as a therapeutic option for patients with tachyarrhythmias mediated by an accessory atrioventricular pathway. The technique conventionally implies the introduction of several catheters into the heart for assessment of electrophysiological parameters as well as for localization of the accessory pathway and may last for several hours. METHODS AND RESULTS: Thirty-four patients with Wolff-Parkinson-White syndrome and a delta wave pattern indicative of an overt (i.e., capable of consistent antegrade conduction) left-sided free-wall accessory pathway underwent attempts at radiofrequency current ablation of the pathway with the use of just one catheter. No patient had a previous electrophysiological study. The catheter was introduced into the left ventricle close to the mitral annulus and was used for pathway localization as well as for ablation. The approach was completely successful in 30 patients (88%). In the remaining four patients, ablation of the pathway was achieved by using the multiple-catheter approach. Overall procedure duration was 2.0 +/- 1.1 hours; radiation exposure time was 22.8 +/- 20.4 minutes (median, 17.3 minutes). There were no acute complications. CONCLUSIONS: The single-catheter approach to radiofrequency current ablation of overt left-sided free-wall accessory pathways is feasible, safe, and effective in the majority of patients. The approach requires considerable investigator experience but significantly reduces procedure duration and radiation exposure time.
Adolescent↗
[The effect of step rate and muscle force on the rate response of activity-modulated cardiac pacemaker].
Programming of activity-modulated pacemakers allows an individual adaptation of rate response. In 26 pacemaker patients (Activitrax n = 16; Synergyst n = 10; Medtronic) it was tested whether rate-response parameters can already be programmed under consideration of patient's characteristics. At a fixed rate-response setting (VVIR/VOOR mode, pacing rate range: 60-130 ppm, MEDIUM/7) four treadmill exercise tests were performed: three step-rate controlled tests with 40, 80, and 120 steps/min and a symptom-limited exercise test with 1 km/h initial speed and 1 km/h speed increments every second minute. Maximal pacing rates at 80 steps/min (72 +/- 14 ppm) and 120 steps/min (90 +/- 6 ppm) were higher than at 40 steps/min (63 +/- 6 ppm). Forced steps with a step rate of 40/min resulted in a higher pacing rate compared to normal steps. At symptom-limited exercise, maximum pacing rates increased to 102 +/- 19 ppm with a range from 60 ppm to 124 ppm. Positive correlations were found between maximum step rate and maximum pacing rate (r = 0.55), between exercise duration and maximum pacing rate (r = 0.70), and between exercise duration and maximum step rate (r = 0.78). Patients with an exercise tolerance up to 5 km/h achieved pacing rates from 91 and 124 ppm, but patients with restricted exercise tolerance had lower maximum pacing rates due to their lower maximum step frequencies. Step rate and body force are important movements in the generation of body vibrations.
Aged↗