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K den Dulk

Publications and source records attributed to K den Dulk.

At least 19 recordsLinked to original sources
PubMed1992

Apparent P wave undersensing in a DDD pacemaker post exercise.

Wenckebach behavior of DDD pacemakers occurring when the P-P interval varies between the programmed upper rate interval and the total atrial refractory period is symmetrical in a sense that the pacemaker response during atrial rate acceleration is similar to the pacemaker response during atrial rate deceleration. This phenomenon can be observed in all patients with persistent AV block in whom a DDD pacemaker is implanted, during exercise testing when the spontaneous atrial rate exceeds the selected upper rate, i.e., the programmed upper rate interval. However, this phenomenon will not be observed in all patients with intermittent intact AV conduction during exercise. In this case report we describe a patient who showed an asymmetrical response during a bicycle exercise test. There was 1:1 atrial sensing ventricular pacing until the atrial rate exceeded the upper rate of 140 ppm, while atrial sensing was restored during recovery when the conducted sinus rhythm had decreased to 105 beats/min.

Aged↗
PubMed1992

Efficacy of automatic multimodal device therapy for ventricular tachyarrhythmias as delivered by a new implantable pacing cardioverter-defibrillator. Results of a European multicenter study of 102 implants.

BACKGROUND: Third-generation implantable cardioverter-defibrillators are devices designed to treat ventricular tachycardia (VT) and ventricular fibrillation (VF) by means of overdrive pacing, cardioversion, or defibrillation. So far, the efficacy of tiered therapy has been documented only in small series. Therefore, a European multicenter clinical evaluation study of a new tachyarrhythmia control device, the Medtronic PCD pacer-cardioverter-defibrillator with epicardial patch-lead configuration, was undertaken. METHODS AND RESULTS: We report on 102 patients (mean age, 55 +/- 13 years) from 11 European centers. PCD devices implanted between May 1989 and February 1991 were included. The patients suffered from hemodynamically significant ventricular tachyarrhythmias not suppressed by antiarrhythmic drug therapy and unrelated to acute myocardial infarction; one patient had nonsustained VT and severely depressed left ventricular function. Seventy patients had coronary artery disease with old myocardial infarctions, 23 had cardiomyopathies of various etiologies, and nine patients had no detectable heart disease. Mean ejection fraction was 36 +/- 14% (range, 10-76%). Mean intraoperative defibrillation threshold (51 patients) was 10.6 +/- 5.1 J (range, 2-18 J). The documented follow-up ranged from 1 to 21 months (mean, 9.4 +/- 5.8 months), or 79.9 cumulative patient-years. Perioperative mortality was 3.9%. The actuarial survival rate at 12 months was 91%. One sudden arrhythmic death occurred. Sixty patients (58%) received device therapy. Seventeen patients had therapies only for "VF" episodes, 16 patients only for VT, and 28 patients for VT and "VF" episodes. Based on device memory data, 1,235 spontaneous VT episodes were detected and treated in 43 patients. Twelve hundred four of these VT episodes received painless initial antitachycardia pacing therapy, restoring sinus rhythm in 91%. The 108 ongoing episodes received 209 multiple therapeutic attempts. Eighty-five additional overdrive pacing therapies restored sinus rhythm in 30%. Initial ineffective antitachycardia pacing therapies received 51 cardioversion pulses. The success rate was 61%. Seventy-three additional cardioversion pulses were delivered to backup ineffective pacing therapy as well as ineffective secondary cardioversion pulses. Their success rate was only 40%. Two hundred eighty-six spontaneous episodes were detected in 44 patients as "VF." Overall defibrillation efficacy was 97.6%. CONCLUSIONS: The implanted device nearly eliminates sudden arrhythmic death in patients with documented, potentially fatal ventricular tachyarrhythmias. Automatic tiered therapy is highly effective to restore sinus rhythm, provided that an integrated two-zone tachycardia detection algorithm is used, assigning lower tachycardia rates to overdrive pacing and/or cardioversion and higher tachycardia rates to defibrillation. In general, spontaneous VTs can be terminated by automatic overdrive pacing, and painful or disturbing countershock therapies are not required to terminate the majority of spontaneous VT episodes.

Death, Sudden, Cardiac↗
PubMed1992

Ambulatory electrocardiography evaluation of supraventricular tachyarrhythmias and bradyarrhythmias.

Long-term ECG recordings are of great value in the diagnosis and management of patients with cardiac arrhythmias. Information from programmed stimulation studies and intracardiac recordings has markedly improved the diagnostic abilities of the person examining the long-term ECG recording. This article discusses how knowledge from intracardiac electrophysiologic studies has resulted in much better recognition of the type and mechanisms of a supraventricular arrhythmia on the Holter record.

Bradycardia↗
PubMed1991

Applicability of the stimulus-T interval for antitachycardia pacing.

UNLABELLED: At the onset of tachycardia, the refractory period (RP) changes together with the tachycardia termination window. We evaluated dogs with total atrioventricular (AV) block to determine if stimulus-T interval (STI) can be used to adjust the coupling interval(s) of an antitachycardia pacemaker in relation to changes in RP. Endocardial STI was recorded continuously together with six surface ECG leads. Steady-state (greater than 2 min) RP was determined for drive cycle lengths (DCL) 400 msec and 900 msec. The test pulse (TP) coupling interval, with DCL 900 msec, was chosen to be equal to the RP of DCL 400 msec. DCL was then changed to 400 msec until TP captured. STI of DCL of beat before capture was gained was measured. DCL was then changed back to 900 msec and the interval determined when capture was lost. TP was then lengthened by 5 msec and the procedure repeated until TP captured immediately upon changing to DCL 400 msec. RESULTS: The difference between RP at onset of pacing at DCL of 400 msec and RP when capture was achieved with the shortest coupling interval was 35-50 (mean 40) msec. This required 35-90 (mean 62) seconds. The correlation coefficient RP to STI was greater than 0.95. CONCLUSIONS: (1) RP changed by as much as 35-50 msec at the onset of an abrupt increase in rate in a 35-90-second period; and (2) STI enables estimation of RP on a beat-to-beat basis. Capture can therefore be predicted from the previous beat and the coupling interval adjusted accordingly in an antitachycardia pacing mode.

Animals↗
PubMed1990

Long-term antitachycardia pacing experience for supraventricular tachycardia.

UNLABELLED: A pacemaker was used to control drug-resistant reentrant supraventricular tachycardia (SVT) in 40 patients. An antitachycardia pacemaker was implanted in 37 for SVT; in one for ventricular tachycardia that could also be used to terminate SVT; in one SVT could be terminated with an activity rate variable pacemaker; and in one a DDD pacemaker was used for prevention and termination of SVT. Twenty patients had AV nodal reentrant tachycardias, eight had tachycardias due to a concealed accessory pathway, eight had a Wolff-Parkinson-White syndrome, three had reentrant atrial tachycardias, and one had atrial flutter. Twenty-two patients were paced from the right atrium, five from the coronary sinus, ten from the right ventricle, and three had a DDD pacemaker. During a total follow-up period of 1,503 (mean 38) months an estimated 16,240 episodes of tachycardia were terminated promptly at home, 58 required several attempts, 57 episodes lasted longer than 30 minutes but did not require medical attention, and 11 required hospital admission. Hospital admission for SVT decreased from one per patient-month (in the 3 months before implantation) to 1 per 137 patient-months after implantation. Additional reentrant tachycardias occurred in 13 patients. Antiarrhythmic drug therapy in combination with a conservative antitachycardia pacing mode was required in four patients paced from the atrium to avoid pacing induced atrial fibrillation. Antiarrhythmic drug therapy was used in 42% of patients to help control SVT. CONCLUSIONS: (1) Drug-resistant SVTs can be safely and effectively managed on the long-term with antitachycardia pacemakers. (2) Rapid termination of SVT improved the quality-of-life significantly by avoiding prolonged episodes of tachycardia and repetitive hospital admissions.

Anti-Arrhythmia Agents↗
PubMed1988

The Activitrax rate responsive pacemaker system.

Bipolar Medtronic Activitrax rate responsive pacemakers were implanted in 31 patients for ventricular (28) or atrial (3) pacing. Mean follow-up was 16 months (range 10 to 26). Twenty pacemakers were implanted after catheter ablation of the His bundle, 7 for sick sinus syndrome. 1 for atrioventricular block and 3 for sick sinus syndrome with atrioventricular block. A rate response value was selected that gave a pacing rate of about 100 pulses/min during walking. Of the 31 patients, all had 24-hour ambulatory electrocardiographic monitoring with diary, 11 walked a 20-minute circuit, including a flight of stairs, and 20 had a treadmill exercise test. In 9 patients the pacing rate could be compared with the underlying sinus rate during exercise and was seen to match it very closely. In 12 patients the pacing rate during car driving was found to be similar to the sinus rate of 5 volunteers under similar conditions (mean minimum and maximum rate was 80 and 99 pulses/min, respectively). No pacing-induced arrhythmias were seen during ambulatory electrocardiographic monitoring. At high pacing rates slightly irregular pacing intervals were sometimes observed, which was due to polarization sensing. Sporadically, 1 pacing interval shortened to the upper rate value, because of a known and now resolved timing anomaly. Neither anomaly was of clinical consequence and the first could be resolved by reprogramming.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Pacemaker syndrome with AAI rate variable pacing: importance of atrioventricular conduction properties, medication, and pacemaker programmability.

A patient who received an AAI Activitrax rate variable pacemaker for treatment of symptomatic sinus bradycardia is described. disopyramide prolonged the anterograde effective refractory period of the fast conducting atrioventricular (AV) nodal pathway to such an extent, that conduction switched to the slow AV nodal pathway at low atrial pacing rates. This gave rise to symptoms of the pacemaker syndrome during moderate exercise because the paced atrial event was conducted with a long, spike to Q interval with occurrence of the paced atrial event just after the preceding QRS complex. A change of medication solved this problem. Programming a bipolar electrode configuration avoided sensing of far-field QRS signals with the associated problems of resetting the basic pacing interval as well as the upper rate interval. AAI rate variable pacing requires careful evaluation of AV conduction properties, AV conduction intervals as well as the influence of medication to be given. The use of multiprogrammable pacemakers with marker channel capability will significantly facilitate the understanding and resolution of anomalous behavior.

Aged↗
PubMed1988

Modern pacemakers: implantable artificial intelligence?

For over twenty years computer programs have been written for applications in cardiology. Approximately one decade ago the first Expert Systems using knowledge on cardiology were built. The use of Expert System shells enabled a breakthrough. Many systems were developed, each covering a small part of cardiology. In the pacing environment Expert Systems can be used to select the optimal pacemaker therapy or to analyze complex pacemaker electrocardiograms. With the help of these artificial intelligence techniques pacemakers can be designed, that behave in an intelligent way. Finally this knowledge representation enables the reproducible simulation of the heart-pacemaker interaction.

Artificial Intelligence↗
PubMed1986

Is there a universal antitachycardia pacing mode?

A pacing mode using automatically increasing number of stimuli with adaptive coupling intervals was evaluated prospectively as a possible universal pacing mode, because a universal mode would save extensive testing and tailoring time. In group 1, which included 7 patients with implanted antitachycardia pacemaker systems, the test mode was compared with the previously tested and tailored mode. In group 2, which included 11 patients undergoing invasive electrophysiologic study, the test mode was compared with the scanning and asynchronous burst mode. There were 4 patients in group 3. The mode was tested prospectively in these 4 patients. Three of these patients were tested after pacemaker implantation (in supine and upright body position and after moderate exercise). The fourth patient had recurring episodes of VT, which were terminated with the test mode via an external lead. Of 209 tachycardias (156 supraventricular tachycardia [SVT] and 53 with VT) studied with the test mode, 1 episode of nonsustained atrial fibrillation was induced from the ventricle and 1 episode of VT was not terminated using the test mode and long coupling intervals. Two episodes of VT in patients with a recent myocardial infarction (MI) required direct-current countershock: due to acceleration in 1 patient and due to VF in 1. All other tachycardias were terminated promptly by the test mode without prior knowledge about successful coupling intervals or number of stimuli. Of the remaining 106 tachycardias studied (69 SVT, 37 VT) the scanning mode failed to terminate 2 episodes of SVT with up to 4 atrial premature beats and induced acceleration of VT in 1 patient with a recent MI.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Detection of insulation failure by gradual reduction in noninvasively measured electrogram amplitudes.

Insulation failure of pacemaker leads may give rise to functional defects such as under- or oversensing, loss of capture or muscle stimulation. An increased incidence of such failures has been reported for the bipolar polyurethane-insulated Medtronic model 6972 pacing lead. It is therefore important to identify techniques that will detect such insulation defects early. A case report is presented in which diminishing electrogram amplitude at follow-up predicted lead failure several months before becoming clinically manifest. This finding suggests that routine measurement of such an electrogram may be a useful tool in predicting impending lead malfunction.

Aged↗
PubMed1986

Merits of various antipacemaker circus movement tachycardia features.

Pacemaker circus movement tachycardia (PCMT) was a significant problem in first generations of DDD pacemakers. Programmability of the atrial refractory period proved to be an effective tool to prevent PCMT except in patients with very long ventriculoatrial (V-A) conduction intervals, because a long atrial refractory period severely limits the maximum tracking rate. In these patients, extension of the atrial refractory period after a VPB, bipolar atrial sensing, adaptation of atrial refractory period to atrial rate, and VPB synchronous atrial stimulation helped limit the incidence of PCMT. Rate smoothing and fallback behavior have given rise to other forms of PCMT. Once initiated, PCMT can be terminated by a single P wave or by means of an appropriately timed atrial stimulus. Recognition by means of continued upper rate pacing may not be helpful in patients with a long V-A conduction interval because their PCMT rate will be low, thus requiring a low upper rate to trigger. Therefore, absolute prevention of PCMT has not yet been achieved, but PCMT is no longer a significant problem in DDD pacing; recognition of PCMT should not be related to the ventricular upper rate limit.

Atrioventricular Node↗
PubMed1985

Arrhythmias induced during termination of supraventricular tachycardia.

Pacing is being used frequently for the treatment of drug-resistant, paroxysmal supraventricular tachycardias (SVT). SVT can usually be terminated by pacing, but arrhythmias may be induced which interfere with the safety of antitachycardia pacing. To quantify these pacing-induced arrhythmias, 453 attempts to terminate SVT in 111 patients were analyzed. The patients were 6 to 73 years old (mean 41); 62 were male. Seventy-six patients had SVT using an accessory atrioventricular bypass, and 35 patients had intranodal SVT. Single and then, if required, multiple ventricular and atrial premature beats and overdrive pacing were delivered from the atrium and ventricle. A pacing-induced arrhythmia occurred in 9% of all attempts (34% of patients). Atrial flutter or fibrillation (AF) was the most frequent arrhythmia (in 8% of all attempts and sustained in 75%). Atrial vs ventricular pacing resulted in a 12% vs 2% incidence of AF. AF was unrelated to age, sex, atrial size and SVT type, and was predominantly induced by multiple premature beats. In 6 patients a different SVT and in 2 patients a nonsustained ventricular tachycardia was induced. In 6 patients SVT could only be terminated by initiating another arrhythmia. Thus, AF is frequently induced during attempted pacing termination of SVT. To limit the risk of AF, a single premature beat should preferentially be used to terminate SVT. In 6% of patients, SVT can only be terminated by inducing another arrhythmia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

Automatic pacemaker termination of two different types of supraventricular tachycardia.

A new antitachycardia pacemaker system was used in a 58 year old woman to terminate two different types of supraventricular tachycardia by a single automatic pacing mode. During the invasive electrophysiologic study before pacemaker implantation (in the absence of medication), sustained episodes of atrioventricular (AV) nodal reentrant tachycardia and two short-lasting episodes of nonsustained atrial tachycardia were induced. After implantation, sustained episodes of both AV nodal tachycardia and atrial tachycardia were initiated. Both arrhythmias could be terminated reproducibly by a single pacing mode.

Automation↗
PubMed1985

PACTOT: a reprogrammable software pacing system.

The long battery life in modern pacemakers has created the need for pacemakers in which all the parameters can be changed and updated. The availability of such a system has potential advantages: new pacing techniques can be programmed without reoperation; the number of different pacemaker systems in stock in a hospital can be reduced to this reprogrammable unit; and, finally, this system can be of great help in designing and evaluating new pacing strategies.

Computers↗