A 54-year-old man received a four chamber pacing system for severe congestive heart failure (NYHA functional Class IV). His ECG showed a left bundle branch block (200-msec QRS duration) with 200-msec PR interval, normal QRS axis, and 90-msec interatrial interval. An acute hemodynamic study with insertion of four temporary leads was performed prior to the implant, which demonstrated a significant increase in cardiac output and decrease of pulmonary capillary wedge pressure. A permanent pacemaker was implanted based on the encouraging results of the acute study. The right chamber leads were introduced by cephalic and subclavian approaches. The left atrium was paced with a coronary sinus lead, Medtronic SP 2188-58 model. An epicardial Medtronic 5071 lead was placed on the LV free wall. The four leads were connected to a standard bipolar DDD pacemaker, Chorus 6234. The two atrial leads were connected via a Y-connector to the atrial channel of the pacemaker with a bipolar pacing configuration. The two ventricular leads were connected in a similar fashion to the ventricular channel of the device. The right chamber leads were connected to the distal poles. The left chamber leads were connected to the proximal poles of the pacemaker. Six weeks later, the patient's clinical status improved markedly with a weight loss of 17 kg and disappearance of peripheral edema. His functional class was reduced to NYHA II. Four chamber pacing is technically feasible. In patients with evidence of interventricular dyssynchrony, this original pacing mode probably provides a mechanical activation sequence closer to the natural one.(ABSTRACT TRUNCATED AT 250 WORDS)

Constant rapid pacing may suppress arrhythmias, but it is usually poorly tolerated in the long term. We report a pilot study of a new pacing algorithm for overdrive suppression of atrial premature complexes (APCs) and atrial fibrillation (AF), which prevents postextrasystolic pauses and varies the pacing rate in response to the frequency of APCs. The algorithm was tested in a multiple crossover study for 24 hours in dual chamber pacemakers implanted in 70 patients. Comparison was made on ambulatory recordings between the number of atrial arrhythmias commencing with the algorithm active and inactive. In all cases, the algorithm functioned as designed. No patient was aware of its operation, and no malignant arrhythmias were induced. The 36 recordings that showed atrial arrhythmia were included for analysis. The effects of the algorithm were: APCs (estimated from pacemaker statistics) reduced in 18 patients, increased in 8 (P = 0.02); atrial salvos reduced in 12, increased in 4 (P = 0.041); and AF reduced in 11, increased in 8 (P = NS). In all patients with frequent AF (> 5 episodes in total), fewer episodes occurred when the algorithm was active. We conclude that the algorithm is safe and well tolerated, reduces atrial ectopic activity, and may reduce the frequency of sustained atrial fibrillation.

Despite the low long-term incidence of high-degree atrioventricular (AV) block and the known negative effects of ventricular pacing, programming of the AAI mode in patients with sinus node dysfunction (SND) remains exceptional. A new pacing mode was, therefore, designed to combine the advantages of AAI with the safety of DDD pacing. AAIsafeR behaves like the AAI mode in absence of AV block. First- and second-degree AV blocks are tolerated up to a predetermined, programmable limit, and conversion to DDD takes place in case of high-degree AV block. From DDD, the device may switch back to AAI, provided AV conduction has returned. The safety of AAIsafeR was examined in 43 recipients (70 +/- 12-year old, 24 men) of dual chamber pacemakers implanted for SND or paroxysmal AV block. All patients underwent 24-hour ambulatory electrocardiographic recordings before hospital discharge and at 1 month of follow-up with the AAIsafeR mode activated. No AAIsafeR-related adverse event was observed. At 1 month, the device was functioning in AAIsafeR in 28 patients (65%), and the mean rate of ventricular pacing was 0.2%+/- 0.4%. Appropriate switches to DDD occurred in 15 patients (35%) for frequent, unexpected AV block. AAIsafeR mode was safe and preserved ventricular function during paroxysmal AV block, while maintaining a very low rate of ventricular pacing. The performance of this new pacing mode in the prevention of atrial fibrillation will be examined in a large, controlled study.

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Stored data in implantable pacemakers have rarely been used as a diagnostic tool because of the complexity. Our group has developed software called AIDA, providing an automatic interpretation of data stored in memories of the Chorus (ELA medical) pacemaker. We compared the results of AIDA analysis to surface ECG Holter interpretation in 59 patients (age 75 +/- 9 years). In 33 cases, neither AIDA nor the Holter found any anomaly. Eleven patients demonstrated episodes of supraventricular tachycardia (SVT), confirmed by AIDA in ten patients; AIDA failure was due to nonsustained episodes of SVT not inducing mode switch. Loss of atrial sensing, pacemaker-mediated tachycardia, and ventricular extrasystoles were detected by AIDA in ten patients. Traditional Holter missed three cases. This initial study confirms that stored pacemaker data, automatically interpreted can provide reliable information over a 24-hour period.