Mid-term follow-up after maze IV procedures for concomitant atrial fibrillation.

BACKGROUND: We performed a retrospective analysis of the maze IV procedures performed in our surgical department for concomitant atrial fibrillation. METHODS: Preoperative, in-hospital and postoperative follow-up data were collected from 46 consecutive patients who underwent the maze IV operation between April 2006 and December 2010. All electrocardiograms and Holters were reviewed. RESULTS: One patient died in-hospital. During a mean follow-up of 25 +/- 16.3 months seven patients died: two related to a hemorrhagic stroke, one due to right ventricular failure, the remainder deaths were not cardiac related. The success rate, defined as no recurrence of AF or atrial flutter with a blanking period of 6 months postoperatively, was 73.7%. Plots of probability of freedom of atrial fibrillation over time are drawn and reach a stable level after one year. CONCLUSIONS: The mid term results of the maze IV procedures for concomitant atrial fibrillation are very good. The results are stable for the remainder of follow-up.

Improved differentiation of the ventricular evoked response from polarization by modification of the pacemaker impulse.

The Autocapture feature, implemented in the Microny and Regency pacemakers of St. Jude Medical, continuously controls the effectiveness of ventricular stimulation by detection of the evoked response. Proper sensing of this signal depends on the magnitude of the polarization, which should be minimal. Therefore, the conjunctive use of low polarization electrodes is recommended. Further, the pacing impulse of these pacemakers has a biphasic waveform consisting of a stimulus followed by a fast discharge pulse. This study compares polarization of a modified pacing impulse with the default pacing impulse, and its effect on the ability to activate the Autocapture function when used with different types of electrodes. In 45 patients, acute measurements of the polarization and the evoked response were performed at random on the modified pacing impulses of a custom designed Regency and on the default stimuli of a standard Regency. The following bipolar leads were used: 20 Medtronic 4024 CapSure, 12 Pacesetter 1450T, and 13 Pacesetter 1470T. Using the default pacing impulse, polarization and evoked response were significantly larger with the Medtronic 4024 CapSure compared to the low polarization leads. The polarization to evoked response ratio was more frequently acceptable for activation of the Autocapture with the Pacesetter leads. In all leads the modified pacing impulse was characterized by significantly smaller polarization with the most prominent reduction in the Medtronic 4024 CapSure. The differences in the pacing impulse did not affect the evoked response. With the programmability of the fast discharge pulse, the requirements to activate the Autocapture function were fulfilled in 29 (94%) of 31 patients with the modified pacing impulse, compared to 22 (71%) of 31 patients with the standard pacing impulse. The modified pacing impulse decreased the "polarization to evoked response" ratio, and by that improved the conditions for activation of the Autocapture function.

Quality of life in patients with complete heart block and paroxysmal atrial tachyarrhythmias: a comparison of permanent DDIR versus DDDR pacing with mode switch to DDIR.

A prospective double-blind randomized crossover study was done in 15 patients with complete heart block and intermittent ATs. The pacemaker was randomly programmed to dual chamber inhibited rate responsive pacing (DDIR) and to DDDR with mode switch, for 1 month each. An event recorder was given to the patients and after each period, a QOL questionnaire was obtained. Based on telemetric data, all but two patients had AT during follow-up. The duration and frequency of these episodes were not related to mode settings. AV synchrony was better preserved in DDDR (P < 0.05). Most symptom-related event recordings during DDIR showed loss of AV synchrony; DDDR with mode switch caused symptoms due to tracking of ST. Overall the QOL score was not different between the modes. Fewer somatic complaints were noted during DDDR pacing than during baseline. DDIR stimulation showed no difference. Twelve patients preferred the period of DDDR pacing; one experienced severe symptoms during DDIR. In conclusion, patients with paroxysmal AT, DDDR with mode switch, and DDIR had no influence on the occurrence, nor on the duration of AT episodes. AV synchrony was better preserved in DDDR, which was also associated with fewer somatic complaints compared to the baseline. In DDDR, symptoms were observed when ST was tracked. QOL was comparable, although more patients preferred DDDR.

Low-energy intracardiac shocks during atrial fibrillation: effects on cardiac rhythm.

The effect on ventricular rate of intracardiac shocks for atrial fibrillation was studied in 13 patients receiving 95 shocks. Shocks were synchronized to the R wave and were delivered after R-R intervals > 500 msec, with increasing strength (20 to 400 V). In 10 patients, conversion to sinus rhythm was achieved in this way. Noneffective shocks increased the mean first postshock R-R interval (compared with 20 V as baseline), for shocks > or = 140 V. The R-R prolongation correlated with the shock level (r = 0.936, p < 0.01). Subsequent R-R intervals were comparable to baseline. A similar trend toward longer first postshock intervals was observed for effective shocks. However, the maximal first R-R interval after noneffective shocks had no relation to the voltage. The number of pauses > 1500 msec tended to increase with voltage (noneffective shocks). Pauses > 2500 msec were exceptional (4 of 85 noneffective shocks). No symptomatic bradycardia occurred. In subsequent intervals (cycles 2 through 10) no pauses > 2500 msec were noted. It is concluded that atrial defibrillation attempts between the right atrium and coronary sinus prolong R-R intervals, in relation to administered energy, but without the need for backup pacing.

A randomized, single-blind crossover comparison of the effects of chronic DDD and dual sensor VVIR pacing mode on quality-of-life and cardiopulmonary performance in complete heart block.

The aim of this study was to compare DDD and dual sensor VVIR (activity and QT) pacing modes in complete AV block (CAVB). Eighteen patients (14 men and 4 women, aged 70 +/- 6.5 years) implanted with a dual chamber, dual sensor pacemaker for CAVB with normal sinus node chronotropic function were studied. A quality-of-life and cardiovascular symptom questionnaire, and a treadmill exercise test were completed after a period of VVIR and a period of DDD pacing, each lasting 1 month. Overall quality-of-life and cardiovascular symptoms did not significantly differ, though three patients felt discomfort during VVIR mode. There was no significant statistical difference in cardiopulmonary parameters. DDD and VVIR modes yielded the following respective data: maximum heart rate = 105.7 +/- 21.8 beats/minute versus 107.6 +/- 21.6 beats/minute (NS); maximum workload = 60 +/- 33.4 W versus 59.3 +/- 37.8 W (NS); treadmill duration = 10.1 +/- 3.8 minute versus 10.1 +/- 3.6 minute (NS); oxygen consumption at anaerobic threshold = 14.6 +/- 4.1 mL/kg per minute versus 14.9 +/- 4.6 mL/kg per minute (NS); maximum minute ventilation = 49.6 +/- 9L/min versus 46 +/- 12 L/min (NS); and respiratory quotient = 1.08 +/- 0.15 versus 1.08 +/- 0.13 (NS). We conclude that, during a 1-month follow-up period, no difference was found between DDD and dual sensor VVIR (QT and activity) pacing modes in CAVB patients with regard to quality-of-life and cardiopulmonary performance, though a trend toward an increased sense of well being was noted with the DDD mode.

A new transvenous internal cardioverter-defibrillator: implantation technique, complications, and short-term follow-up.

Twenty-four patients with ventricular fibrillation or sustained ventricular tachycardia underwent implantation of a new transvenous defibrillator. All patients had a device implanted without thoracotomy. High placement of a shock lead in the anonymous vein and inversion of the shock-wave polarity allowed avoidance of placement of subcutaneous patches. Implantation time decreased from 138 minutes for the first 12 patients to 82 minutes for the last 12 patients, with 4 and 11 subpectoral pockets, respectively. Three patients required a minor reintervention. No bleeding or infection occurred. One episode of pulmonary edema and one pulmonary embolism were seen in the postoperative course. No postoperative deaths were observed. During a mean follow-up period of 4.12 months, 58% of the 24 patients had symptomatic arrhythmic episodes, with shocks in 50% of the 24. Inappropriate shocks were delivered in three cases (atrial fibrillation and T-wave sensing). One episode was not terminated even with four internal shocks. One patient had ventricular fibrillation because of a sensing problem. By reprogramming of sensitivity, back-up pacing, and adjustment of drug therapy these arrhythmic complications could be prevented. Pectoral implantation of a cardioverter-defibrillator is easy and can be performed by cardiologists experienced in pacemaker implantation. Careful postoperative observation, reprogramming after the first spontaneous event, and prehospital discharge induction of ventricular fibrillation will prevent arrhythmic complications.

The "automatic mode switch" function in successive generations of minute ventilation sensing dual chamber rate responsive pacemakers.

Automatic mode switch (AMS) from DDDR to VVIR pacing is a new algorithm, in response to paroxysmal atrial tachyarrhythmias. With the 5603 Programmer, the AMS in the Meta DDDR 1250 and 1250H (Telectronics Pacings Systems, Inc.) operates when VA is shorter than the adaptable PVARP. With the 9600 Programmer, an atrial protection interval can be defined after the PVARP. The latest generation, Meta DDDR 1254, initiates AMS when 5 or 11 heart cycles are > 150, 175, or 200 beats/min. From 1990 to 1993, 61 patients, mean age 61 years, received a Meta DDDR: in 24 a 1250, in 12 a 1250H and in the remaining 25 a 1254 model. Indication for pacing was heart block in 39, sick sinus syndrome in 15, the combination in 6, and hypertrophic obstructive cardiomyopathy in 1. Paroxysmal atrial tachyarrhythmias were present in 43. All patients had routine pacemaker surveillance, including 52 Holter recordings. In 32 patients, periods of atrial tachyarrhythmias were observed, with proper AMS to VVIR, except during short periods of 2:1 block for atrial flutter in 4. In two others, undersensing of the atrial arrhythmia disturbed correct AMS. With the 1250 and 1250H model, AMS was observed on several occasions during sinus rate accelerations in ten patients. This was never seen with the 1254 devices. Final programmation was VVIR in 2 (chronic atrial fibrillation), AAI in 1 (fracture of the ventricular lead), VDDR in 1 (atrial pacing during atrial fibrillation), DDD in 5, and DDDR in 53, 48 of whom had AMS programmed on.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of six minute walking test in patients with single chamber rate responsive pacemakers.

OBJECTIVE: To validate a simplified exercise protocol (the six minute walk) as a means of evaluating pacing modes and rate responsive pacemakers. DESIGN: Two groups of patients with different pacemaker types (activity and dual sensor) were randomly assigned to four consecutive pacing settings (fixed rate--or VVI at 60, 85, and 110/min, and optimal rate response--or VVIR). A third group of elderly patients without arrhythmias or conduction disturbances formed a control population. SETTING: Ambulatory consultation for patients with a pacemaker in a tertiary referral centre for treatment of arrhythmias. SUBJECTS: 16 patients with rate responsive pacemakers for complete heart block and limited functional capacity and 13 controls with normal chronotropic competence. INTERVENTIONS: Submaximal exercise protocol with 6 minutes walking and continuous recording of electrocardiogram. MAIN OUTCOME MEASURES: Achieved distance and scored degree of exertion during walking in the four settings in the patients with a pacemaker; differences in rate behaviour in VVIR mode between the two pacemaker types; comparison of the pacing rate with the heart rate of the control population. RESULTS: The six minute walk was performed better in VVIR than VVI 60. In VVI 85 the distance was also significantly longer than in VVI 60. The rise in pacing rate of activity pacemakers was steeper than that of the dual sensor pacemakers and differed from the heart rate in the controls at 90 seconds. CONCLUSIONS: The studied test protocol was able to show differences in exercise capacity between pacing modes. Different rate responses between the evaluated sensor types could be established. The six minute walking test gives enough information to program and reprogram single chamber rate responsive pacemakers.

Anomalous origin of the left coronary artery from the pulmonary artery.

A 20-year-old woman underwent successful operative correction of anomalous origin of the left coronary artery from the pulmonary artery by left internal mammary artery bypass graft. The clinical, hemodynamic, and angiographic features of this unusual case are presented. Different therapeutic options are discussed.

[Aberrant origin of the left coronary artery from the pulmonary artery as cause of ventricular fibrillation in a young woman]. / Aberrante oorsprong van de linker coronairarterie uit de A. pulmonalis als oorzaak van ventrikelfibrillatie bij een jonge vrouw.

An anomalous left coronary artery originating from the pulmonary artery is a rare, but frequently lethal congenital disorder. A wide range of symptoms due to heart failure and myocardial ischaemia may appear soon after birth. We describe a young woman who was admitted to the hospital after resuscitation for ventricular fibrillation. An anomalous origin of the left coronary artery from the pulmonary trunk was diagnosed. An echocardiographic evaluation in this adult patient illustrated the haemodynamic disturbances in the coronary circulation. The thallium scintigram showed reversible perfusion defects on exercise. Ischaemia may be implicated in the pathogenesis of the arrhythmia. Our patient was treated with an arterial graft and ligation of the left coronary artery at its origin.

Clinical observations with a dual sensor rate adaptive single chamber pacemaker.

The Topaz model 515 (Vitatron B.V.) is a dual sensor rate responsive pacemaker for single chamber stimulation. It can be driven by activity counts (ACT) and QT interval measurements. Inappropriate rate modulation due to one sensor can be corrected by "sensor cross-checking." It was implanted in ten patients (20-86 years) of whom seven had complete heart block and atrial arrhythmias. After implantation T-wave amplitude ranged from 0.9 mV-3.5 mV. T-wave sensing ranged from 88%-99% in 9/10 patients at the follow-up of 3 weeks. Eight patients remained in default setting of the activity threshold, after evaluation with a short walking test. An exercise test was performed on all patients. In one test, QT sensing was marginal because of lead implantation in the right ventricular outflow tract. Therefore, this pacing rate was only modulated by ACT sensing. All others were tested with equal contribution of information from both sensors (ACT = QT). In 7/9, rate response was satisfactory. When the treadmill was repeated with ACT in five of these seven patients, rate generally accelerated too fast. In one patient the setting was adjusted to "QT > ACT," because of inappropriate acceleration due to activity sensing, in another it was adjusted to "QT < ACT" because of delayed response to activity. The pacing rate and the ACT during treadmill tests in "QT = ACT" mode were more closely correlated in the first 3 minutes, compared with the last 3 minutes. We feel that rate modulation with this new pacemaker is adequate. Sensor blending and sensor cross-checking are of clinical importance.

Radiofrequency ablation of incessant ventricular tachycardia to prevent multiple defibrillator shocks.

In a patient who received frequent shocks from an implantable defibrillator, a slow ventricular tachycardia originating in a large left ventricular aneurysm was ablated with radiofrequency current. Pacemapping perfectly matched the spontaneous, incessant arrhythmia. Local entrainment was present, along with a mid-diastolic potential of 65 microV. Application of 30 W terminated tachycardia within 12 s. He had no more recurrences during follow-up.