High incidence of atrial fibrillation after dual chamber pacemaker implantation - implication on the use of atrial defibrillation mode pacemakers

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The Osteoporosis Society of Hong Kong (OSHK): 2013 OSHK Guideline for Clinical Management of Postmenopausal Osteoporosis in Hong Kong

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Initial clinical experience with a new self-retaining left ventricular lead for permanent left ventricular pacing

This study evaluated the performance of a new lead for permanent left ventricular (LV) pacing via the coronary sinus (CS) in four men and nine women (mean age = 71 ± 13 years) with sick sinus syndrome. It consists of a 75-cm-long, 4.8-Fr, unipolar ventricular lead with a distal portion preshaped in an S curve to provide steerability and stability within the CS. Its efficacy and stability for permanent LV pacing were tested at implant, predischarge, and at 1, 3 and 6 months of follow-up. The lead was successfully implanted in 11/13 patients (85%) within a mean fluoroscopy time of 35 ± 22 minutes. The final positions of the electrodes at the tip of the lead within venous tributaries of the CS were: (1) anterior (n = 2, 18%); (2) posterolateral (n = 5, 45%); and (3) the lateral (n = 4, 36%). Unsuccessful implants were due to unstable lead position (n = 1), or high pacing threshold (n = 1). There was no postprocedural lead dislodgment or significant changes in the R wave amplitude, LV pacing threshold and lead impedance up to 6 months of follow-up. In summary, this initial experience suggests that this new lead offers safe and reliable permanent LV pacing via the CS in the majority of patients and may be used in isolation or in conjunction with right ventricular pacing for biventricular synchronization.link_to_subscribed_fulltex

Efficacy and tolerability of continuous overdrive atrial pacing in atrial fibrillation

Overdrive right atrial pacing has been used to prevent atrial fibrillation, but its efficacy in atrial fibrillation prevention and the patient tolerability and quality of life during high rate pacing remain uncertain. The objective of this study was to test the effects of a consistent atrial pacing algorithm that automatically paced the atrium at 30ms shorter than the sinus P-P interval for atrial fibrillation prevention. Fifteen patients with sick sinus syndrome implanted with a Thera DR (model 7940 or 7960, Medtronic Inc.) were randomly programmed to rate adaptive dual chamber pacing (DDDR) or DDDR+consistent atrial pacing mode, each for an 8-week study period. The efficacy of consistent atrial pacing was assessed by the number of automatic mode switching and the number of premature atrial complexes. Symptoms and quality of life were assessed by the SF-36 quality of life questionnaire and an atrial fibrillation symptom checklist. The percentage of atrial pacing increased from 57±32% to 86±28%. Overall, there was no significant difference in the number of automatic mode switching episodes between DDDR and DDDR+ consistent atrial pacing (47±90 vs 42±87, P> 0·05), but a significant reduction in premature atrial complexes by 74·7% (P< 0·001). There was no undue increase in atrial rate by the DDDR+consistent atrial pacing mode versus DDDR (63±13 vs 70±7bpm). There was no significant difference in quality of life scores and symptom severity on frequency between the two modes of pacing, but a trend towards a lower frequency of symptoms in the DDDR+consistent atrial pacing mode compared with baseline (29·5±10·2 vs 25·1±9·7, P=0·07). An algorithm that provides consistent atrial overdrive pacing can suppress atrial fibrillation triggering premature atrial complexes without the need to increase the overall atrial rate compared with conventional pacing. The algorithm appears to be well-tolerated, but further studies are needed to address the clinical impact of this atrial fibrillation prevention algorithm. © 2000 The European Society of Cardiology.link_to_subscribed_fulltex

Reversible impairment of left and right ventricular systolic and diastolic function during short-lasting atrial fibrillation in patients with an implantable atrial defibrillator: A tissue doppler imaging study

AF with a fast ventricular response may cause ventricular mechanical impairment, though whether short-lasting AF with satisfactory rate control may affect ventricular function is unknown. This study investigated if prompt cardioversion by an implantable atrial defibrillator (IAD) may prevent left (LV) and right ventricular (RV) systolic and diastolic dysfunction. Ten patients (mean age 61 ± 9 years, 8 men) with paroxysmal AF without structural heart disease who received an IAD were studied by echocardiography and tissue Doppler imaging (TDI) for both ventricles. Measurements were made during baseline sinus rhythm and at 1-minute, 20-minute, 4-hour, and 1-week postcardioversion of an episode of spontaneous AF. The occurrence AF and the ventricular rate were monitored at 2-hour intervals by the device. There were 50 episodes AF with a mean duration of 8.8 ± 8.9 days (2 hours to 37 days). There was no difference in M-mode measured L V fractional shortening and ejection fraction between baseline sinus rhythm and after cardioversion, However, the TDI derived myocardial systolic velocity (TDI-S) was significantly lower at 1-minute postcardioversion and was normalized at 1 week in both LVs (baseline: 5.7 ± 1.8, 1 minute: 4.2 ± 1.0, 20 minutes: 4.3 ± 0.9, 4 hours: 4.8 ± 1.0, 1 week: 5.5 ± 1.8 cm/s; P 48 hours) resulted in a more depressed TDI-S in LV (> 48 hours: 4.2 ± 1.0, ≤ 48 hours: 5.3 ± 1.3 cm/s; P < 0.01). Shocks in sinus rhythm did not affect uny of the above echocardiographic parameters. Therefore, despite adequate rate control, short-lasting AF impairs systolic and diastolic function in both ventricles, which improves gradually after cardioversion. Early restoration of sinus rhythm by an IAD minimizes ventricular dysfunction. TDI is a sensitive tool to assess early systolic and diastolic dysfunction.link_to_subscribed_fulltex