Arterial thromboembolism in patients with sick sinus syndrome: prediction from pacing mode, atrial fibrillation, and echocardiographic findings.
OBJECTIVE: To evaluate whether thromboembolism in sick sinus syndrome can be predicted by pacing mode, atrial fibrillation, or echocardiographic findings. METHODS: Patients were randomised to single chamber atrial (n = 110) or ventricular (n = 115) pacing. They were divided into subgroups with and without brady-tachy syndrome at time of randomisation. The occurrence of atrial fibrillation and thromboembolism during follow up were investigated and compared with echocardiographic findings. RESULTS: The annual risk of thromboembolism was 5.8% in patients with brady-tachy syndrome randomised to ventricular pacing, 3.2% in patients without brady-tachy syndrome randomised to ventricular pacing, 3% in patients with brady-tachy syndrome randomised to atrial pacing, and 1.5% in patients without brady-tachy syndrome randomised to atrial pacing. In atrial paced patients without brady-tachy syndrome at randomisation and without atrial fibrillation during follow up, the annual risk of thromboembolism was 1.4%. Left atrial size measured by M mode echocardiography was of no value in predicting thromboembolism. CONCLUSIONS: Arterial thromboembolism in patients with sick sinus syndrome is very common and is associated primarily with brady-tachy syndrome at randomisation and with ventricular pacing. The risk of thromboembolism is small in atrial paced patients in whom atrial fibrillation has never been documented. (+info)
Acute performance of steroid-eluting screw-in leads for atrial free wall pacing.
The aim of this study was to clarify the acute performance of steroid-eluting screw-in leads in comparison with that of nonsteroid screw-in leads for atrial free wall pacing. In 114 cases (68 males, 46 females, average age 70 years) with atrial free wall pacing by screw-in leads, pacing thresholds and P-wave amplitudes were compared at the time of implantation and 1 week later between 68 cases of nonsteroid and 46 cases of steroid-eluting screw-in leads. No significant differences were seen between the 2 groups at implantation in either voltage or current thresholds measured at pulse widths of 0.1, 0.3, 0.6, 1.0, 2.0 ms, or P-wave amplitudes. Pulse width thresholds at outputs of 2.5 V and 5.0 V were significantly lower for steroid leads 1 week after implantation (2.5 V: 0.34+/-0.27 ms nonsteroid vs. 0.12+/-0.08 ms steroid, p<0.001; 5.0 V: 0.12+/-0.08 ms nonsteroid vs. 0.06+/-0.02 ms steroid, p<0.01). P-wave amplitudes after 1 week were significantly higher for steroid leads (2.6+/-0.7 mV nonsteroid vs 3.0+/-1.2 mV steroid, p<0.001). Threshold rise, including pacing failure, was observed in 15 (22%) of the non-steroid leads, but in only 1 (2%) of the steroid leads. In conclusion, steroid-eluting screw-in leads suppress the acute rise of pacing thresholds in the right atrial free wall and their acute performance is better than that of non-steroid leads. These results suggest that appropriate low-output atrial pacing is feasible immediately after implantation. (+info)
Exercise-induced uncommon atrioventricular nodal reentrant tachycardia with sick sinus syndrome: a case report.
Exercise seldom provokes tachycardia in patients with paroxysmal supraventricular tachycardia (PSVT). This report presents a case of exercise-induced uncommon atrioventricular nodal reentrant tachycardia (AVNRT) with sick sinus syndrome. Treadmill exercise testing provoked AVNRT of long RP' with good reproducibility. Uncommon AVNRT was confirmed by the lack of atrial pre-excitation during PSVT and para-Hisian pacing. The patient has been successfully treated with verapamil and DDD pacing for 5 years. (+info)
Effect of physiological mechanical perturbations on intact human myocardial repolarization.
OBJECTIVE: The objective of this study was to investigate the relationship between acute decreases in right ventricular volume during Valsalva strain (with resultant changes in autonomic neural tone) and measures of local endocardial repolarization time independent of heart rate and autonomic neural tone. METHODS: Patients implanted with a stimulus to T wave (Stim-T) sensing pacemaker specially adapted to output a validate measure of beat to beat local repolarization (n = 9) performed Valsalva manoeuvers (40 mmHg for 15 s) while paced at a cycle length of 500 ms. Stim-T intervals were measured before and after autonomic blockade (Block: 0.03 mg/kg i.v. atropine +/- 0.15 mg/kg propranolol). Right ventricular end diastolic volume was estimated by simultaneous 2D-echocardiography. RESULTS: Without autonomic blockade, compared to baseline, repolarization significantly prolonged during Valsalva strain (1.1 +/- 0.7%) and shortened during release (-1.4 +/- 1.0%). After block, strain related repolarization prolongation was also observed (1.0 +/- 0.6%), with significantly less release related repolarization shortening (-0.8 +/- 0.8%) compared to pre-block (P < 0.05). Right ventricular end diastolic volume decreased during strain by 11 +/- 10 and 9 +/- 16% from baseline, pre- and post-block respectively (P < 0.05). CONCLUSION: In a chronically instrumented human model, an acute physiologic volume reduction modestly prolongs right ventricular repolarization independent of changes in rate or autonomic tone. (+info)
Concerns about sources of electromagnetic interference in patients with pacemakers.
Electromagnetic noise is rapidly increasing in our environment so electromagnetic interference (EMI) with pacemakers (PM) may become a more important problem despite technological improvements in PM. The aim of this study was to evaluate the kinds of EMI which affect the quality of life of PM patients. The participants (1,942 Japanese Association for Pacemaker Patients: Pacemaker-Tomonokai) were asked to respond to a questionnaire about their major EMI troubles, and 1,567 patients (80.7%) responded by mail. The main concerns were from mobile telephones (MT) (39%), magnetic resonance imaging (MRI) (17%), electronic kitchen appliances, automobile engines and high voltage power lines. If possible, PM implantation sites should be carefully selected not only according to the physician's convenience but also considering information on each patient's habits and physical limitations. (+info)
Regional myocardial blood flow in patients with sick sinus syndrome randomized to long-term single chamber atrial or dual chamber pacing--effect of pacing mode and rate.
OBJECTIVES: This study aimed to evaluate regional myocardial blood flow (MBF) and global left ventricular ejection fraction (LVEF) during chronic pacing in patients with sick sinus syndrome (SSS) randomized to either single chamber atrial (AAI) or dual chamber (DDD) pacing. BACKGROUND: Experimental studies indicate that chronic pacing in the right ventricular apex changes regional MBF, thereby compromising left ventricular function. METHODS: Thirty patients (age 74 +/- 10 years) were randomized to AAI (n = 15) or DDD (n = 15) pacemakers. After 22 +/- 7 months of pacing, MBF was quantified with 13N-labeled ammonia positron emission tomography scanning at 60 beats per min and 90 beats per min. Patients in the DDD group furthermore underwent MBF measurement at temporary AAI pacing, 60 beats per min. Myocardial blood flow was assessed in the anterior, lateral, inferior and septal regions, and the global mean MBF was calculated. Left ventricular ejection fraction was determined by echocardiography at pacemaker implantation and at the time of MBF measurements. RESULTS: Myocardial blood flow at rates 60 and 90 beats per min did not differ between the AAI and DDD groups. During temporary AAI pacing in the DDD group, MBF was significantly higher than during DDD pacing in both the inferior (p = 0.001) and septal (p = 0.004) regions and also globally (0.61 +/- 0.15 vs. 0.53 +/- 0.13 mL x g(-1) x min(-1), p = 0.005). In the DDD group, LVEF decreased from pacemaker implantation to time of MBF measurements (0.61 +/- 0.09 vs. 0.56 +/- 0.07, p = 0.013). Left ventricular ejection fraction during temporary AAI pacing at time of MBF measurements was not different from LVEF at pacemaker implantation. CONCLUSIONS: In patients with SSS, chronic DDD pacing reduced inferior, septal and global mean MBF as well as LVEF, as compared with temporary AAI pacing. The LVEF reversed to baseline level during temporary AAI pacing despite 22 months of permanent ventricular pacing preceding it. Augmenting pace rate to 90 beats per min increased MBF equally in the two treatment groups. (+info)
Exchange of pacing or defibrillator leads following laser sheath extraction of non-functional leads in patients with ipsilateral obstructed venous access.
Occlusion of the subclavian or brachiocephalic vein in pacemaker or defibrillator patients prohibits ipsilateral implantation of new leads with standard techniques in the event of lead malfunction. Three patients are presented in whom laser sheath extraction of a non-functional lead was performed in order to recanalise the occluded vein and to secure a route for implantation of new leads. This technique avoids abandoning a useful subpectoral site for pacing or defibrillator therapy. The laser sheath does not affect normally functioning leads at the same site. (+info)
Permanent pacemaker insertion in a district general hospital: indications, patient characteristics, and complications.
This report reviews the experience of permanent pacemaker insertion in a district general hospital (catchment population of 350 000) and makes a comparison with the national database and other hospitals in the UK. METHODS: The records of all patients receiving a permanent pacemaker in the inclusive period January 1996 to December 1998 were reviewed. Data collected included number of patients paced each year, age, sex, indications, and complications. RESULTS: In the three years reviewed 200 patients received new permanent pacemakers, a rate of 190 per million population per year, which is similar to the national implantation rate of permanent pacemakers but lower than that of most European countries (see discussion). The majority of patients paced were elderly (75% were above the age of 70 years). Atrioventricular block (including complete heart block, 45%, and Mobitz type 2 block, 12.5%) was the commonest indication for permanent pacemaker insertion, followed by sick sinus syndrome (25%) and these findings are comparable to those reported previously. However, carotid sinus syndrome was responsible for 16% of the patients paced and this was higher than that reported in the national database (6.5%). Only 1% of the pacemaker modes used was inappropriate and the complication rate was low at 3%. CONCLUSIONS: This report confirms that permanent pacemaker insertion can be effectively and safely provided locally for the increasingly ageing population. The implantation rate both locally and nationally is still much lower than that of some countries in Europe. (+info)