Analysis of terminal arrhythmias stored in the memory of pacemakers from patients dying suddenly

AIMS

Stored electrograms or marker channels are available in most of modern cardiac pacemaker models. We sought to analyse these information to uncover terminal events of pacemaker patients dying suddenly. Method and results We made post-mortem pacemaker (PM) interrogations in 19 patients dying suddenly out of hospital between the years 1997 and 2005 (mean age 59 +/- 13 years, 90% males). The systems had activated arrhythmia monitoring algorithms. Indications of pacing were sick sinus syndrome in seven, AV-block in five, and heart failure due to asynchrony in seven cases. The interrogated pacemakers were CHORUS 7034 (n = 12), CONTAK TR (n = 2), and INSYNC III (n = 5). For interpretation stored marker channels and electrograms were analysed. The mean observation time after PM implantation prior death was 2.11 +/- 1.44 years, the mean left ventricular ejection fraction from the last available echo examination in the year prior death was 27.5 +/- 8%, mean age was 63 +/- 12 years. In 17/19 cases (89%), a tachycardia (most likely ventricular tachycardia) was found correlating to the time of death. The mean cycle length of the terminal arrhythmia was 307 +/- 144 (250-344) ms, corresponding to a heart rate of 195 +/- 95 (174-240) bpm. We found no evidence of specific pacemaker-related problems such as electronic failure, battery depletion, or undersensing.

CONCLUSIONS

Post-mortem analysis of arrhythmia monitoring of pacemaker patients revealed tachycardias (most likely ventricular tachycardia) to be related to sudden death. These findings give some insight in mechanisms of terminal events in this group.

First experience with a new active fixation coronary sinus lead

AIMS

Coronary sinus (CS) lead implantation is a technically challenging procedure owing to variable vein anatomies and a high dislocation rate. Therefore, CS lead technology has undergone evolutionary changes during the last 10 years. The mode of fixation has been a passive one up to now. We want to describe our first clinical experience with the newly available active fixation lead 4195 in terms of dislocation rate and stability of thresholds compared with conventional models.

METHODS AND RESULTS

From 1999 to February 2007, we implanted 403 CS leads in 368 patients. Leads were categorized into three different groups on the basis of their fixation mechanism: straight (Easytrak I and Situs OTW; n = 54), curved (Attain 4193 and 4194, Corox, Aescula, Situs ULD; n = 308), and active (Attain 4195; n = 41). Operative and follow-up data were prospectively noted and checked for significance between groups during the first 3 months after implantation. Kaplan-Meier analysis of long-term lead function was also performed. Straight and curved CS leads suffered from significantly more dislocations compared with active fixation (P < 0.001). The active fixation lead (4195) has a stable threshold over time compared with a significant rise after 24 h and thereafter in straight (62%) and curved leads (20%). However, retraction of an active fixation CS lead may be a difficult issue as outlined in two cases requiring pullback of a 4195 lead owing to phrenic nerve stimulation (one unsuccessful despite vigorous traction).

CONCLUSION

The active fixation lead 4195 using retention lobes yielded stable thresholds over time and seems to be superior to conventional leads in terms of dislocation. However, extraction may be a difficult or even impossible task.

RHABDOMYOLYSIS AFTER ADDITION OF DIGITOXIN TO CHRONIC SIMVASTATIN AND AMIODARONE THERAPY

Rhabdomyolysis is a well known side effect of statin therapy. Several drugs may increase its risk by drug-drug interactions. In particular, patients with heart disease receive more and more different compounds to cope with all the pathomechanisms involved and may therefore be of high risk for side effects. We report a case of rhabdomyolysis in a patient with heart failure on a multi-drug regimen caused by a drug interaction between chronic statin therapy (simvastatin), amiodarone and newly administrated digitoxin. The patient recovered fully after cessation of simvastatin therapy, the other drugs were given continuously. Potential mechanisms of this event are discussed. Most interesting in this case is that rhabdomyolysis occurred only after starting digitoxin after long-term therapy with the statin.

Long-term hemodynamic benefit of biventricular pacing depending on coronary sinus lead position

BACKGROUND

Acute studies in cardiac resynchronization therapy (CRT) showed that hemodynamic effects may depend on the coronary sinus (CS) lead position. However, there are no data on the longterm effect of CS lead position.

METHODS

In 45 heart failure patients with left bundle branch block and QRS >150 ms (age 59+/-10 years, 17 dilative cardiomyopathy, 23 ischemic, 5 valvular), biventricular pacemakers were implanted. CS leads were positioned in posterior (P, n=15), lateral (L, n=19) or, if no other option available, anterior (A, n=11) side branches. Before and 6 months after implantation, clinical state, echocardiography, brain natriuretic peptide (BNP) and right heart catheterization were evaluated.

RESULTS

Baseline parameters were similar between groups. After 6 months, there were 32/34 responders in groups P and L compared to 7/11 responders in group A (94 vs groups P and L: Arterial pressure +8 and +9% vs +2%; PCWP -23 and -15% vs -4%, pulmonary pressure -18 and -12% vs -3% (p<0.01 for A vs P+L); cardiac index +21 and +12% vs +11% (p=0.03 for A vs P). BNP was reduced by 55, 35, and 27% (p=0.05 for A vs P). Ejection fraction increased in P and L by 40 and 41%, respectively, but only by +19% in A (p<0.03 for A vs P+L).

CONCLUSION

Chronic CRT improves ejection fraction, BNP and hemodynamic measurements predominantly in patients with lateral and posterior CS lead positions. Anterior lead positions should be avoided.