Biomedical subjects

Jaswinder Gill

Publications and source records attributed to Jaswinder Gill.

6 recordsLinked to original sources

PubMed2005

Impact of dual chamber pacing on the incidence of atrial and ventricular tachyarrhythmias in recipients of implantable cardioverter defibrillators.

Recent observations suggest that frequent dual-chamber pacing in recipients of implantable cardioverter defibrillators (ICD) may adversely influence clinical outcomes. This prospective, multicenter study examined the relationship between the frequency of atrial (%AP) and ventricular pacing (%VP) and the incidence of atrial (AT) and/or ventricular tachyarrhythmias (VT) in a standard ICD population. A total of 141 consecutive patients with primary and secondary ICD indications were studied. Continuous arrhythmia detection with a dual-chamber ICD revealed paroxysmal AT in 60 (43%) and VT in 72 (51%) patients within 6 months of device implantation. Far-field oversensing of ventricular signals occurred in 13% of all "atrial tachy response" mode switches. Without adjustment for covariates, a higher %AP was associated with an increased incidence of AT (P < 0.05). However, this association remained only weakly significant after adjustment for covariates using a multivariate model. High New York heart failure functional classes correlated significantly with AT (P = 0.02) and VT (P = 0.007). Rate-modulated pacing, programmed in 1/3 of patients, correlated with occurrence of AT (P = 0.006), but not with occurrence of VT. With respect to dual-chamber pacing, a %AP >/= 48% combined with a %VP > 40% was associated with an increased probability for VT. In conclusion, AT and VT occurred frequently within 6 months after dual-chamber ICD implantation. High rates of DDD/R stimulation were associated with a trend toward higher incidence of AT, VT, or both.

Aged↗

PubMed2005

Clinical performance of a ventricular automatic capture verification algorithm.

BACKGROUND: This study was conducted to evaluate the clinical performance of the ventricular automatic capture feature as implemented in the Insignia I Ultra pacemaker system (Guidant) utilizing a variety of ventricular leads. Currently, the optimal programming of the pacemaker output considers both pacemaker efficiency (prolonging battery longevity) and patient safety (adequate safety margin). The ability of a pacemaker to automatically adjust the ventricular output above the pacing threshold while maintaining the appropriate safety margin has been explored since the early 1970s and is only available today in conjunction with a specific low polarization lead system. METHODS: One hundred and five patients were enrolled from 17 European centers utilizing 31 different types of ventricular leads were followed through their 3-month follow-up visit. There were no restrictions on the type of ventricular leads used. RESULTS: The average mean difference between the commanded autothreshold test (0.652 + 0.335 V) and the manual threshold test (0.651 + 0.335 V) was 0.001 + 0.49 (P < 0.0001). The average mean difference between the ambulatory autothreshold test (0.696 + 0.322 V) and the commanded autothreshold test (0.682 + 0.315 V) was 0.002 + 0.74 (P < 0.0001). Holter recordings confirmed that there were no loss of capture incidences without a backup pulse being delivered. In addition, the mean number of backup pulses delivered in a 24-hour period was less than 0.1% of the total number of paced beats. CONCLUSIONS: This study provided that the automatic capture feature while using a variety of leads accurately determines the ventricular stimulation threshold and safely delivers a backup pulse when required.

Adult↗

PubMed2005

Impaired renal function and atherosclerosis in a Pakistani cohort.

OBJECTIVE: To investigate the relationship of creatinine and calculated glomerular filtration rate (GFR) with coronary arterial disease (CAD) in Pakistani patients. SUBJECTS: Four hundred individuals with chest pain; 200 with angiographic disease matched with 200 without occlusive disease. DESIGN: A prospective case-control study. SETTING: A tertiary referral cardiology unit in Pakistan. RESULTS: Impaired renal function as estimated by calculated GFR was common in this population. Creatinine and glomerular filtration rate, as calculated by the Cockcroft-Gault (CG) and Modification of Diet in Renal Disease (MDRD) formulae, were associated with CAD and atherosclerotic burden in Pakistani patients. Calculation of creatinine clearance, correcting for age, sex and body mass index, showed that clearance was 81 (17-257) mL/min/1.73 m2 in patients with CAD compared with 88 (23-167) mL/min/1.73 m2 in controls with a significant number of patients (18.5 vs. 6.5%; RR = 2.85; p < 0.001) showing significant renal impairment (< 60 mL/min/1.73 m2) by CG and more by the MDRD equation (26 vs. 9%; RR = 2.88; p < 0.001). The unadjusted odds ratios for CAD for a GFR < 60 mL/min/1.73 m2 were 3.66 (1.87-7.16) and 3.29 (1.81-6.01), respectively and, after adjustment for diabetes, smoking, insulin resistance, inflammation and apolipoprotein A1, 1.04 (1.02-1.09) and 1.04 (1.02-1.09), respectively. CONCLUSIONS: Impaired renal function is common in Pakistani patients with coronary arterial disease and is strongly associated with a risk of atherosclerosis independent of insulin resistance.

Adult↗

PubMed2004

Clinical experience with a new detection algorithm for differentiation of supraventricular from ventricular tachycardia in a dual-chamber defibrillator.

INTRODUCTION: Inadequate therapy for supraventricular tachyarrhythmias (SVT) is a frequent problem of implantable cardioverter defibrillators (ICD). Dual-chamber ICDs have been developed to improve discrimination of SVT from ventricular tachycardia (VT). We investigated the positive predictivity, sensitivity, and specificity of a new algorithm, the SMART detection trade mark algorithm, incorporated in the Phylax AV (Biotronik) dual-chamber ICD. METHODS AND RESULTS: Two hundred nine patients (185 men, age 64 +/- 11 years) received a Phylax AV ICD with SMART detection trade mark activated. In 138 of these patients, 1,245 sustained tachycardia episodes with a detailed electrogram were stored in the device during a follow-up period of 10 +/- 6 months. Episodes were correctly classified as ventricular fibrillation (VF, n = 178) in 52 patients, VT (n = 641) in 98 patients, and SVT (n = 385) in 48 patients by the algorithm. Forty-one true SVT episodes (3.3%) were misclassified as VT: atrial fibrillation (n = 7) and flutter (n = 1), sinus tachycardia (n = 12), and other SVT (n = 21). The positive predictivity for VF/VT was 94.5% (95% CI 92.7-95.8) uncorrected and 94.5% (95% CI 92.9-95.8%) corrected with the generalized equation estimation (GEE) method. The positive predictivity for SVT was 100%. The specificity was 88.9% (95% CI 85.6-91.6%) uncorrected and 89.0% (95% CI 85.6-91.6%) corrected with the GEE method with a sensitivity of 100%. CONCLUSION: The SMART detection trade mark algorithm was safe and reliable for the detection of all ventricular tachycardias. Although its specificity was high, it should be improved with regard to SVT to avoid inappropriate ICD therapies.

Adult↗

PubMed2004

Waist-hip ratio and low HDL predict the risk of coronary artery disease in Pakistanis.

OBJECTIVE: To establish risk factor causal associations for coronary artery disease (CAD) in the native Pakistani population. METHODS: We conducted a hospital-based, case-control study of 200 cases with angiographically documented CAD and 200 age- and sex-matched controls without angiographic evidence of CAD. Patients on lipid lowering therapy were excluded. Lifestyle, anthropometric and biochemical risk factors were assessed in both groups. RESULTS: The presence of CAD was associated with current, past or passive smoking, a history of diabetes and high blood pressure, a positive family risk factors in this study; levels were below history of CAD, body fat percentage, waist-hip ratio (WHR), low apolipoprotein A1 or low HDL, lipoprotein (a), glucose, insulin, insulin resistance, C-reactive protein (CRP), total cholesterol to HDL ratio (TC/HDL) and creatinine on univariate conditional logistic regression analysis. In multiple regression analysis, significant independent associations were found with low HDL (OR 0.11; 95% CI 0.04-0.34; p < 0.001) positive family history (OR 1.79; 95% CI 1.09-2.93; p = 0.02), CRP (OR 1.45; 95% CI 1.19-1.75; p < 0.001) and WHR (OR 1.04; 95% CI 1.01-1.08; p = 0.01). Angiograms were also quantified for the extent and severity of CAD by the Gensini scoring system. Quantitative angiographic data showed associations with age (p = 0.01), the duration of diabetes (p = 0.04), WHR (p = 0.06), low HDL (p < 0.001), lipoprotein (a) (p = 0.001), creatinine (p < 0.001) and CRP (p = 0.007). Results indicate that total and LDL cholesterol were not significant currently accepted thresholds for treatment. CONCLUSIONS: The cardiovascular risk profile in this population is consistent with metabolic syndrome where low HDL and WHR can be used to predict the risk of CAD. Results suggest the need to redefine the currently practised approach to CAD management in this population to fit local needs.

Adult↗

PubMed2003

Comparison of impedance minute ventilation and direct measured minute ventilation in a rate adaptive pacemaker.

Respiration rate (RR) and minute ventilation (MV) provide important clinical information on the state of the patient. This study evaluated the accuracy of determining these using a pacemaker impedance sensor. In 20 patients who were previously implanted with a Guidant PULSAR MAX group of pacemakers, the telemetered impedance sensor waveform was recorded simultaneously with direct volume respiration waveforms as measured by a pneumatometer. Patients underwent 30 minutes of breathing tests while supine and standing, and a 10-minute ergonometer bicycle exercise test at a workload of 50 W. Breathing tests included regular and rapid-shallow breathing sequences. RR was determined by a computerized algorithm, from impedance and respiration signals. The mean RR by impedance was 21.3 +/- 7.7 breaths/min, by direct volume was 21.1 +/- 7.6 breaths/min, range 7-66, the mean difference of RR measured by the impedance sensor, as compared with the true measurement, being 0.2 +/- 2.1 breaths/min. During the entire exercise, the mean correlation coefficient between impedance (iMV) and direct measured MV was 0.96 +/- 0.03, slope 0.13 +/- 0.05 L/Omega and range 0.07-0.26 L/Omega. Bland-Altman limits of agreement were +/- 4.6 L/min for MV versus iMV with each patient calibrated separately. The correlation coefficient for iMV versus MV over the entire 10 minutes of exercise, including the initial 4 minutes of exercise, was 0.99. The transthoracic impedance sensor of an implanted pacemaker can accurately detect respiration parameters. There was a large variation between subjects in the iMV versus MV slope during a bicycle exercise test, whereas for each subject, the slope was stable during submaximal bicycle exercise.

Adult↗