Inappropriate Discharge of an Implantable Cardioverter Defibrillator During Atrial Flutter and Intermittent Ventricular Antibradycardia Pacing

Inappropriate Discharge of an ICD. Introduction : Inappropriate discharses of an implantable cardioverter defibrillator (ICD) are troublesome to the patient and sometimes a difficult task for the physician trying; to identify and treat the cause.
Methods and Results : For the first time, we report a mechanism of inappropriate ICD discharges during episodes of atrail flutter with a slow ventricular response and intermittent antibradycardia pacing. The episodes occurred in tow patients and were triggered by the unique sensing alogorithm of the Ventitex Cadence® V-100 in combination with the tripolar CPI Endotak® 072 transvenous defibrillation lead, which provides integrated bipolar sensing.
Conclusion : Besides treatment of the underlying arrhythmia, reprogramming of the device, an electrode position far away from the atria, and true bipolar sensing will enhance the performance of ICD systems with respect to the episodes described here. In addition, more flexible sensing algorithms may. in the future, prevent this overall rare complication.     

Benefits and Limitations of Rate Adaptive Pacing Under Laboratory and Daily Life Conditions in Patients with Minute Ventilation Single Chamber Pacemakers

Rate adaptive pacing has been shown to improve hemodynamic performance and exercise tolerance during acute testing. However, there remain concerns about its benefit in daily life and possible complications incurred by unnecessary pacing. This double-blind crossover study compared the benefit of rate adaptive (SSIR) versus fixed rate (SSI) pacing under laboratory and daily life conditions in 20 rate incompetent patients with minute ventilation single chamber pacemakers (META II). The heart rate (HR) response during three different exercise tests (treadmill, bicycle ergomctry, walking test) was correlated with the Holler findings during daily life in either pacing mode. The maximal HR was significantly higher in the SSIR-mode compared to the SSI-mode, both during laboratory testing (treadmill: 123 ± 15 vs 93 ± 29 beats/min: ergometry: 118 ± 15 vs 89 ± 27 beats/min; walking test: 127 ± 9 vs 95 ± 26 beats/min, all P values < 0.01) as well as during daily life (Holter: 126 ± 13 vs 103 ± 24 beats/min, P < 0.01). On Holter, the average HR (71 ± 14 vs 71 ± 8 beats/min) and the percentage of paced rhythm (54 % vs 62%, SSI- vs SSIR-mode, P = NS) were not different in either mode. However, despite a 30% rate gain in the SSIR-mode, the exercise capacity remained unchanged, and only 38% of patients preferred the SSIR-mode. Minute ventilation pacemakers provide a physiological rate response to exercise. Irrespective of the protocol used, the findings of laboratory testing are comparable to those during daily life. However, patient selection for rate adaptive single chamber pacing should be made with caution, since the objective benefit of restoring normal chronotropy may subjectively be negligible for most patients.     

Eight year experience with the Bjork-Shiley prosthesis in 833 patients

Between December 1970 and June 1978, 833 patients were operatedupon for isolated mitral valve replacement (MVR: 361 patients),isolated aortic valve replacement (AVR: 345 patients) and aorticplus mitral valve replacement (DVR: 127 patients) by use ofthe Björk-Shiley valve. Operative mortality for the entireseries was 15%. The five year survival rate, including operativemortality, calculated by the actuarial method was 81.4% forMVR, 73.1% for AVR and 66.8% for DVR. The five year survivalrate of operative survivors was 94.9% for MVR, 85% for AVR and83.2% for DVR. The five year complication-free survival rate(death/removal/embolus-free survival rate) including operativemortality was 69.7% for MVR, 71.8% for AVR and 62.8% for DVR.The postoperative hemodynamic result was evaluated in 58 consecutivepatients with AVR and DVR. End-diastolic volume fell after operationfrom 161 to 104 ml/m² in AVR and from 156 to 103 ml/m² in DVR.Ejection fraction increased from 54 to 65% in AVR and from 50to 61% in DVR. We conclude: (1) actuarial analysis of prosthesis related deathand complications suggests that the Björk-Shiley valveis an excellent choice when using a mechanical device; (2) asignificant improvement of left ventricular function resultsafter Björk-Shiley valve implantation.     

Crystal structures of the even and odd bolaform amino acid derivatives (11-N-[benzyloxycarbonyl-L-alanyl] aminoundecanoyl)-L-alanyl benzyl ester and (12-N-[benzyloxycarbonyl-L-alanyl]aminododecanoyl)-L-alanyl benzyl ester

Reaction of two α,ω-aminocarboxylic acids with N- and C-protected alanine leads to bolaform compounds with two secondary amide groups on one end and one such group at the other end. Unsymmetric sheet-like structures are formed in the crystals. (11-N-[Benzyloxycarbonyl-L-alanyl]aminoundecanoyl)-L-alanyl benzyl ester (1) and (12-N-[benzyloxycarbonyl-L-alanyl]aminododecanoyl)-L-anyl benzyl ester (2) form triclinic crystals (spacegroup P1, No.1) with a= 4.917, b= 5.614, c= 29.02 Å, α= 88.40, β= 93.50, γ= 100.21°, Z=1 (1) and a= 4.954, b= 5.613, c= 30.23 Å, α= 93.44, β= 90.07, γ= 104.15°, Z=1 (2). The crystal structures were solved via direct methods and refined to R= 0.040 (1) and 0,078 (2) from 2441 and 2125 reflections. © Munksgaard 1997.     

Long-Term Effects of Dynamic Atrial Overdrive Pacing on Sleep-Related Breathing Disorders in Pacemaker or Cardioverter Defibrillator Recipients

Introduction: Sleep-related breathing disorders occur in 20–30% of Europeans and North Americans, including 10% of sleep apnea syndrome (SAS). A preliminary study suggested that atrial overdrive pacing with a fixed heart rate might alleviate SAS. However, it is not known whether dynamic atrial overdrive pacing alleviates SAS.
Methods: Patients with indications for a dual chamber pacemaker or implantable cardioverter-defibrillator (ICD) were screened for SAS using the Pittsburgh Sleep Quality Index (PSQI) questionnaire. If PSQI was >5, cardio-respiratory polygraphy was performed before and 4 and 7 months after device implantation. Patients were randomized to algorithm ON–OFF (group A) or OFF–ON (group B) and the apnea-hypopnea index (AHI) was measured.
Results: Out of 105 consecutive patients, 46 (44%) had a positive PSQI. This analysis included 12 patients (mean age = 61 ± 10 years, body mass index 28.9 ± 6.5 kg/m², left ventricular ejection fraction = 38.3 ± 13.6%; 10 men). All patients suffered from obstructive or mixed SAS. There were no significant differences in PSQI or AHI between baseline and follow-up or between the two study groups. Therefore, the study was terminated ahead of schedule.
Conclusions: The prevalence of obstructive or mixed SAS was high in pacemaker or ICD recipients and reduced left ventricular ejection fraction. In these patients, long-term dynamic atrial overdrive pacing using did not improve PSQI or SAS. Therefore, patients with relevant obstructive or mixed SAS should not be offered atrial pacing therapy.     

Symphysitis following transrectal biopsy of the prostate

Transrectal ultrasound-guided needle biopsy of the prostate is a widely accepted technique to obtain prostatic tissue for histological examination. Severe complications are rarely seen. We report a case of symphysitis causing hospitalization and severe pain and discomfort of the patient. Possible etiologic factors are traumatic osseous lesions and transport of rectal bacteria to the periosseous region. Especially in small prostates, care should be taken to avoid this condition. Prolonged perioperative antibiotic prophylaxis is mandatory.     

Optimized Pulse Durations Minimize the Effect of Polarity Reversal on Defibrillation Efficacy with Biphasic Shocks

There are conflicting results on the effect of polarity change on the defibrillation efficacy of biphasic shocks possibly caused by different shock durations. The goal of the present study was to investigate the influence of polarity reversal on defibrillation efficacy for different biphasic shock durations in a porcine animal model. In eight anesthesized pigs using a transvenous/submuscular lead system DFTs for 4 phase 1 durations were determined: 8.1 ms, 6 ms, 3.8 ms and 1.7 ms. The phase 1/phase 2 ratio was constant at 60%/40%. For cathodal shocks, the defibrillation coil in the right ventricular apex was the cathode during phase 1 and for anodal shocks it was the anode. For both polarities, the strength-duration curve revealed a DFT minimum at 3.8 ms (cathodal shocks: 21.3 +/- 6.4 J, P < 0.001; anodal shocks: 21.9 +/- 8 J, P = 0.05). For anodal shocks and phase 1 durations of 1.7, 3.8, and 6 ms there was no significant difference of the stored energy at the DFT compared to cathodal shocks. In contrast, significantly lower DFTs were observed for anodal shocks with a phase 1 duration of 8.1 ms (28.8 +/- 6.4 J compared to 33.1 +/- 5.9 J for cathodal shocks, P = 0.006). The effect of lower defibrillation energy requirements with polarity reversal depends on the total biphasic shock duration; for the pulse duration with the lowest DFT, polarity reversal does not increase defibrillation efficacy of biphasic shocks.