Biomedical subjects

N Sulke

Publications and source records attributed to N Sulke.

6 recordsLinked to original sources

PubMed1992

"Subclinical" pacemaker syndrome: a randomised study of symptom free patients with ventricular demand (VVI) pacemakers upgraded to dual chamber devices.

OBJECTIVE: To determine whether symptom free patients with single chamber pacemakers benefit from dual chamber pacing. DESIGN: A randomised double blind crossover comparison of ventricular demand (VVI), dual chamber demand (DDI), and dual chamber universal (DDD) modes after upgrading from a VVI device. SETTING: Cardiology outpatient department. PATIENTS: Sixteen patients aged 41-84 years who were symptom free during VVI mode pacing for three or more years. INTERVENTION: Pacemaker upgrade during routine generator change. MAIN OUTCOME MEASURES: Change in subjective (general health perception, symptoms) and objective (clinical assessment, treadmill exercise, and radiological and echocardiographic indices) results between pacing modes before and after upgrading. RESULTS: 75% preferred DDD, 68% found VVI least acceptable with 12% expressing no preference. Perceived general well-being and exercise capacity (p less than 0.01) and treadmill times (p less than 0.05) were improved in DDD mode but VVI and DDI modes were similar. Clinical, echocardiographic, radiological, and electrophysiological indices confirmed the absence of overt pacemaker syndrome, although mitral and tricuspid regurgitation was greatest in VVI mode (p less than 0.01). CONCLUSIONS: Most patients who were satisfied with long term pacing in VVI mode benefited from upgrading to DDD mode pacing suggesting the existence of "subclinical" pacemaker syndrome in up to 75% of such patients. The DDI mode offered little subjective or objective benefit over VVI mode in this population and should be reserved for patients with paroxysmal atrial arrhythmias. VVI mode pacing should be used only for patients with very intermittent symptomatic bradycardia or atrial fibrillation with a good chronotropic response during exercise.

Adult↗

PubMed1992

Paradoxical emboli in elderly patients.

We report two elderly patients who each had a patent foramen ovale (PFO) and were considered to have had paradoxical emboli. In one patient the PFO was detected by contrast two-dimensional echocardiography, whereas in the other it was demonstrated at post-mortem examination. This is an unusual but treatable condition, particularly difficult to diagnose in older people and probably occurring more frequently than is generally suspected.

Aged↗

PubMed1991

A randomized double-blind crossover comparison of four rate-responsive pacing modes.

The aim of this study was to compare, both subjectively and objectively, four modern rate-responsive pacing modes in a double-blind crossover design. Twenty-two patients, aged 18 to 81 years, had an activity-sensing dual chamber universal rate-responsive (DDDR) pacemaker implanted for treatment of high grade atrioventricular block and chronotropic incompetence. They were randomly programmed to VVIR (ventricular demand rate-responsive), DDIR (dual chamber demand rate-responsive), DDD (dual chamber universal) or DDDR (dual chamber universal rate-responsive) mode and assessed after 4 weeks of out-of-hospital activity. Five patients, all with VVIR pacing, requested early reprogramming. The DDDR mode was preferred by 59% of patients; the VVIR mode was the least acceptable mode in 73%. Perceived "general well-being," exercise capacity, functional status and symptoms were significantly worse in the VVIR than in dual rate-responsive modes. Exercise treadmill time was longer in DDDR mode (p less than 0.01), but similar in all other modes. During standardized daily activities, heart rate in VVIR and DDIR modes underresponded to mental stress. All rate-augmented modes overresponded to staircase descent, whereas the DDD mode significantly underresponded to staircase ascent. Echocardiography revealed no difference in chamber dimensions, left ventricular fractional shortening or pulmonary artery pressure in any mode. Cardiac output was greater at rest in the dual modes than in the VVIR mode (p = 0.006) but was similar at 120 beats/min. Beat to beat variability of cardiac output was greatest in VVIR mode (p less than 0.0001), with DDIR showing greater variability than DDD or DDDR modes (p less than 0.05). Mitral regurgitation estimated by Doppler color flow imaging was similar in all modes, but tricuspid regurgitation was significantly greater in VVIR than in dual modes (p less than 0.03). Subjects who preferred the DDDR mode and those who found the VVIR mode least acceptable had significantly greater increases in stroke volume when paced in the DDD mode than in the ventricular-inhibited (VVI) mode at rest (22%) when compared with subjects who preferred other modes (2%, p = 0.03). No other objective variable was predictive of subjective benefit from any rate-responsive pacing mode. Thus, dual sensor rate-responsive pacing (DDDR) is superior objectively and subjectively to single sensor (VVIR, DDIR and DDD) pacing and subjective benefit from dual chamber rate-augmented pacing is predictable echocardiographically.

Adult↗

PubMed1990

Quantitative analysis of contribution of rate response in three different ventricular rate responsive pacemakers during out of hospital activity.

The contribution of rate response provided by three different types of rate responsive pacemaker (Sensolog, Meta, and Vitatron TX) was assessed in 25 patients during out of hospital activity. Pacemakers were optimally programmed and full disclosure 24-hour Holter ECG recordings were obtained during everyday activities. Close visual analysis of these tracings revealed that rate response is active for less than 15% of the 24-hour study period with high rate response (paced rate above 100 beats/min) for just 5% of the day showing peak activation between 1600 and 2000 hours. Low rate response (paced rate below 100 beats/min but 5 beats above base rate) was maximal between 0800 hours and midday and comprised 10% of all heart beats during the study period. Thirty percent of study patients were nonpacemaker dependent and rate response in these subjects was significantly (P less than 0.001) less active between 0800 hours and midday than in pacemaker dependent patients though it was equivalent at all other times. Nonpacemaker dependent patients achieved natural sinus response in the morning and tended to rely on pacemaker supplied rate response in the latter part of the day.

Activities of Daily Living↗

PubMed1990

Is accurate rate response programming necessary?

Exercise capacity and general well-being are improved by appropriately programmed rate responsive pacemakers when compared to fixed rate units. Ten patients had activity sensing DDDR units implanted for combined AV block and sinus node incompetence. Ten patients had Sensolog activity sensing VVIR units implanted for complete heart block. The effects of over and under programming of rate response in both dual and single chamber activity sensor rate adaptive pacemakers has been assessed subjectively by visual analog scales and specific activity questionnaires and objectively by graded treadmill testing and the performance of standardized daily activities. Patients were randomly programmed to absent rate response (VVI in the Sensolog group), hyporesponsive (DDD in the dual chamber group), appropriate response (VVIR, DDDR according to Manufacturer's instructions) and over responsive (VVIR+, DDDR+) in a double-blind crossover design. Thirty percent of patients demanded early crossover from VVI, 30% from DDDR+ and 50% from VVIR+. Perception of Exercise Capability was similar to objective exercise treadmill times which were shorter in VVI than in VVIR or VVIR+ (P less than 0.05) or control subjects (P less than 0.001). There was no difference between any dual chamber mode or control subjects. General well-being was poorest in DDDR+ and VVIR+ modes despite objective improvement in exercise capacity. Symptoms were least in VVIR and DDDR and all but one patient chose appropriate programming as their overall preferred mode. Thus, even inaccurate rate response programming results in similar and improved exercise capacity compared to absent rate response but overprogramming is unacceptable to most patients, confirming that appropriate programming and sensor specificity is critical in rate responsive pacing.

Arrhythmia, Sinus↗

PubMed1990

Inappropriate discharges by the implantable cardioverter defibrillator during postoperative testing: implications for intraoperative assessment.

Inappropriate shocks were delivered to a patient while in sinus rhythm by an implantable cardioverter defibrillator (ICD) during routine prehospital discharge testing. This was induced by the standard programmer when the "read" telemetry sequence was initiated. The ICD was removed and found to suffer from electrical artifact that was sensed as ventricular tachycardia during telemetry. To avoid inadvertent telemetry-induced shocks during routine testing, all ICDs should be interrogated, using a standard programmer, intraoperatively, with the unit in "defibrillation on" mode.

Aged↗