Karel den Dulk

Adverse Events With Transvenous Implantable Cardioverter-Defibrillators A Prospective Multicenter Study

BACKGROUND A newly developed classification system relates adverse events to the surgical procedure or the function of the implantable defibrillator. METHODS AND RESULTS Adverse events were monitored during prospective clinical evaluation of the Medtronic model 7219 Jewel ICD and were classified according to the definitions of the ISO 14155 standard for device clinical trials into 3 groups: severe and mild device-related and severe non-device-related adverse events. In addition, events were related to the surgical procedure, treatment with the device, or cardiac function. Seven hundred seventy-eight patients were followed up for an average of 4.0 months after ICD implantation. In total, 356 adverse events were observed in 259 patients. At 1, 3, and 12 months after ICD implantation, 99%, 98%, and 97% of the patients, respectively, survived; 95%, 93%, and 92%, respectively, were free of surgical reintervention; and 79%, 68%, and 51%, respectively, were free of any adverse event. Twenty patients died: 6 deaths were related to the surgical procedure, 12 deaths were considered unrelated to ICD treatment, and 2 patients died of an unknown cause. Of 111 nonlethal severe adverse device effects, 47 required surgical intervention, 19 times for correction of a dislodged lead. Inappropriate delivery of therapy was observed 128 times in 111 patients, and the events were typically resolved by reprogramming or drug adjustment. Nine of these required rehospitalization. CONCLUSIONS Approximately 50% of patients experience an adverse event within the first year after ICD implantation. The observed adverse event rate depends on the definitions and the prospective monitoring. The incidence of inappropriate therapy emphasizes the need for improved detection algorithms and for quality-of-life evaluations, especially when considering ICD treatment in high-risk but arrhythmia-free patients.

Improvement in left ventricular function by ablation of atrioventricular nodal conduction in selected patients with lone atrial fibrillation

Left ventricular (LV) function was studied in 30 patients with lone atrial fibrillation (AF) (paroxysmal [n = 27] and persistent [n = 3]) before and after ablation of atrioventricular conduction. In all patients, drug treatment did not control ventricular rate during AF or prevent recurrences of the arrhythmia, or both. LV ejection fraction, and LV end-systolic and end-diastolic, and left atrial dimensions were measured by echocardiography before (mean 7 +/- 10 months, range < 1 to 37) and after (14 +/- 20 months, < 1 to 77) ablation. Before ablation, LV ejection fraction was < or = 50% in 12 patients (group I) and > 50% in 18 (group II). After ablation, LV ejection fraction increased significantly in group I from 43 +/- 8% to 54 +/- 7% (p < 0.0001). There were also significant decreases in LV-end systolic and end-diastolic, and left atrial dimensions. No changes in these parameters were observed in group II. Groups I and II had a significant difference in the duration of AF (group I: mean 11 years, range 8 to 28; and group II: 5 years, 2 to 14) (p < 0.05). No difference was present in age, sex, New York Heart Association functional class for dyspnea, or type of ablation procedure. Thus, some patients with lone AF may show deterioration of LV function, which appears to be related to the duration of the arrhythmia; in these cases, LV function may improve significantly after ventricular rate control is accomplished by ablation of atrioventricular conduction.

Pacemaker Related Tachycardias

Three cases of pacemaker interactive tachycardia are presented. The first two are (artificial) circus movement tachycardias. In the first one the retrograde arm of the tachycardia circuit was provided by the A‐V node and the antegrade arm by an atrial synchronous pulse generator. In the second case, the A‐V node and, coincidentally, an A‐V sequential pulse generator alternately provided the antegrade arm while the retrograde arm was by way of an accessory pathway. In the third case ventricular inhibition during A‐V sequential pacing gave the paced atrial events the chance to be conducted to the ventricles with a long A‐V interval. This resulted in a tachycardia with a rate of 150 bpm, instead of the programmed rate of 110 bpm. (PACE, Vol. 5, July‐August, 1982)

Value of lead V4R for recognition of the infarct coronary artery in acute inferior myocardial infarction.

In 84 patients with an acute inferior wall myocardial infarction (MI) admitted within 10 hours after the onset of chest pain, a right precordial lead V4R electrocardiogram was recorded in addition to the standard 12-lead electrocardiogram. The presence or absence of ST-segment elevation in lead V4R was correlated with results of coronary angiography performed 2 to 26 weeks (mean 10) after MI. Patients were classified into 3 groups: (1) those with a critical stenosis or occlusion proximal to the first right ventricular (RV) branch (27 patients); (2) those with stenosis distal to the right ventricular branch of the right coronary artery (36 patients); and (3) those with stenosis in the left circumflex coronary artery (21 patients). The presence of ST-segment elevation greater than or equal to 1 mm in lead V4R has a sensitivity of 100% and a specificity of 87% for occlusion of the right coronary artery above the first RV branch; the predictive accuracy is 92%. Seven of 36 patients with a distal occlusion of the right coronary artery showed ST-segment elevation of 1 mm or more in lead V4R . The absence of ST-segment elevation greater than or equal to 1 mm in lead V4R excluded proximal occlusion of the right coronary artery. ST-segment elevation in lead V4R was not seen either in 29 of 36 patients with a distal occlusion of the right coronary artery or in all patients with an occlusion of the left circumflex artery. Recording of lead V4R within 10 hours after onset of acute inferior wall MI can give information rapidly about the vessel responsible for MI.(ABSTRACT TRUNCATED AT 250 WORDS)

Myocardial bridging as a cause of paroxysmal atrioventricular block

Paroxysmal atrioventricular (AV) block was induced by exercise in an otherwise healthy young man. The only abnormalities demonstrated at comprehensive cardiac evaluation were: 1) angiographic systolic narrowing of the left anterior descending coronary artery, and 2) reversible radionuclide hypoperfusion of the septum during exercise. It is postulated that ischemia of the conduction system due to systolic milking of the left anterior descending coronary artery was responsible for the paroxysmal AV block in this patient.

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.

Initial Experience with Mode Switching in a Dual Sensor, Dual Chamher Pacemaker in Patients with Paroxysmal Atrial Tachyarrhythmias

Mode switching algorithms have been developed to avoid tracking of atrial fibrillation (AF) or flutter (AFL) during DDD(R) pacing. Upon recognition of AF or AFL, the mode is switched to a nontracking, sensor driven mode. The Vitatron Diamond model 800 pacemaker does this on a beat‐to‐beat basis. Atrial events occurring within a “physiological range” (± 15 beats/min) calculated from a running average of the atrial rate are tracked. When atrial events are not tracked the escape interval is either determined by the sensor(s) or by a fallback algorithm thereby preventing large increases in V‐V interval during mode switching. Loss of atrioventricular (AV) synchrony by atrial premature beats and after an episode of AF or AFL is prevented by atrial synchronization pulses (ASP), which are delivered after a safe interval (timed out from the sensed premature atrial event) has expired and before delivery of the next ventricular stimulus. We implanted 26 such devices in 18 men and 8 women with symptomatic second‐ or third‐degree AV block and paroxysmal AF or AFL. Their ages ranged from 18–84 years (mean 60), and the follow‐up ranged from 2–13 months (mean 8). During pacemaker check‐up, exercise testing or 24‐hour Holter monitoring one or more episodes of mode switching was documented in 8 patients. In these 8 patients a smooth transition (ventricular rate) from sinus rhythm to AF or AFL was documented on one or more occasions, without inappropriate increase in ventricular rate in the DDDR mode. None of the patients complained of palpitations. Appropriate rate response was seen in all patients during Holter monitoring and exercise. Restoration of AV synchrony with ASP was documented many times. In 2 patients the DDIR mode was programmed due to intermittent synchronization of ventricular stimuli to near incessant supraventricular tachycardia, which sometimes gave rise to asymptomatic slightly irregular ventricular paced rhythms below WO beats/min. Recognition of AF or AFL was reliable. No inappropriate increases in ventricular pacing rate were seen at the onset of or during AF or AFL. ASP is an effective method of maintaining AV synchrony and avoiding competitive atrial pacing.

Clinical Experience with Implantable Devices for Control of Tachyarrhythmias

Pacing is becoming an accepted form of treatment for reentry tachycardias. The different pacing modalities available and experience with a patient‐activated antitachycardia pacemaker are presented in this paper. This system has bidirectional communication between pacemaker and pacemaker‐activator and between pacemaker and prescription formulator (which is a sophisticated portable stimulator used for non‐invasive electrophysiological evaluation of the system). This pacemaker was implanted in 18 patients with drug‐resistant tachycardias. Six patients had ventricular tachycardia, 3 had A‐V nodal reentrant tachycardia, 4 had the concealed accessory pathway, and 5 had the WPW syndrome. In the 3 months before implantation the mean number of admissions for termination of tachycardia was 2.1 per patient‐month. During a follow‐up period of 3–26 months only 6 patients were admitted once for termination of tachycardia (0.02 admissions per patient‐month). The reasons for admission of these 6 patients were: defective pacemaker activator in 2 patients, inadequate control of tachycardia in 2 patients, inappropriate use of the device in 1, and inadequate intake of medication in 1. All these problems were solved easily. Eight pacemaker activators required reprogramming, which was done in 5 patients on an out‐patient basis. The interval scanning mode was used in 9 patients. Nine patients required more than 2 stimuli for reproducible termination. A step‐wise increase in number of stimuli was used in 5 patients.

A versatile pacemaker system for termination of tachycardia

Abstract Externally activated pacemaker systems were implanted in 13 patients to control their drug-resistant tachycardias. Four patients had ventricular tachycardia, 2 had atrioventricular nodal reentrant tachycardia, 3 had tachycardias due to a left-sided concealed accessory pathway and 4 had Wolff-Parkinson-White syndrome. Nine patients were paced from the right ventricle, 2 from the right atrium and 2 from the coronary sinus. The pacing system consisted of an implantable pacemaker, an external pacemaker activator and a prescription formulator. The pacemaker can signal sensing by way of radiofrequency signals to the pacemaker activator or prescription formulator. Either 1 of the latter 2 devices then determines whether the sensed rhythm fulfills the tachycardia detection criteria and, if so, controls the delivery of the selected stimulation treatment by the pacemaker. With this bidirectional radiofrequency coupling, tachycardias were noninvasively initiated by the prescription formulator after implantation and at follow-up visits to test and eventually reprogram the pacemaker activator. During a follow-up of 116 patient-months, 624 episodes of tachycardia were effectively terminated by the patients. Incidental failure to terminate occurred in 3 patients because of a defective activator, changes in the electrophysiologic substrate and inappropriate use of the device. These problems were solved by reprogramming, replacement of the activator and education of the patient. Hospital admissions for termination of tachycardia decreased from an average of 2.6 per patient-month (in the 3 months before implantation) to 0.03 per patient-month after implantation (follow-up 4 to 16 months). It is concluded that (1) this programmable externally activated pacemaker system effectively manages drug-resistant tachycardia; (2) this system has the advantage of easy testing, multiple pacing modes and ready reprogrammability; and (3) the marked reduction in hospital admissions makes the system cost-effective.

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)