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Pugazhendhi Vijayaraman

Publications and source records attributed to Pugazhendhi Vijayaraman.

18 recordsLinked to original sources
PubMed2006

Development and testing of an algorithm to detect implantable cardioverter-defibrillator lead failure.

BACKGROUND: Implantable cardioverter-defibrillator (ICD) lead failures often present as inappropriate shock therapy. An algorithm that can reliably discriminate between ventricular tachyarrhythmias and noise due to lead failure may prevent patient discomfort and anxiety and avoid device-induced proarrhythmia by preventing inappropriate ICD shocks. OBJECTIVES: The goal of this analysis was to test an ICD tachycardia detection algorithm that differentiates noise due to lead failure from ventricular tachyarrhythmias. METHODS: We tested an algorithm that uses a measure of the ventricular intracardiac electrogram baseline to discriminate the sinus rhythm isoelectric line from the right ventricular coil-can (i.e., far-field) electrogram during oversensing of noise caused by a lead failure. The baseline measure was defined as the product of the sum (mV) and standard deviation (mV) of the voltage samples for a 188-ms window centered on each sensed electrogram. If the minimum baseline measure of the last 12 beats was <0.35 mV-mV, then the detected rhythm was considered noise due to a lead failure. The first ICD-detected episode of lead failure and inappropriate detection from 24 ICD patients with a pace/sense lead failure and all ventricular arrhythmias from 56 ICD patients without a lead failure were selected. The stored data were analyzed to determine the sensitivity and specificity of the algorithm to detect lead failures. RESULTS: The minimum baseline measure for the 24 lead failure episodes (0.28 +/- 0.34 mV-mV) was smaller than the 135 ventricular tachycardia (40.8 +/- 43.0 mV-mV, P <.0001) and 55 ventricular fibrillation episodes (19.1 +/- 22.8 mV-mV, P <.05). A minimum baseline <0.35 mV-mV threshold had a sensitivity of 83% (20/24) with a 100% (190/190) specificity. CONCLUSION: A baseline measure of the far-field electrogram had a high sensitivity and specificity to detect lead failure noise compared with ventricular tachycardia or fibrillation.

Aged↗
PubMed2006

Right ventricular pacing to assess transisthmus conduction in patients undergoing isthmus-dependent atrial flutter ablation: a new useful technique?

BACKGROUND: Successful radiofrequency (RF) ablation of typical, isthmus-dependent atrial flutter requires establishment and confirmation of bidirectional conduction block across the cavotricuspid isthmus. Low atrial pacing usually is performed from the bipoles of the 20-pole Halo catheter, septal and lateral to the cavotricuspid isthmus ablation line. However, occasionally this is difficult because of high pacing thresholds and/or saturation of the atrial electrograms recorded near the pacing catheter. OBJECTIVES: The purpose of this study was to assess if right ventricular (RV) pacing and resulting retrograde atrial activation can be used to assess conduction block from the septum to the lateral wall in a clockwise direction. METHODS: Thirty-five consecutive male patients (mean age 64 +/- 10 years; mean ejection fraction 42 +/- 13%; mean left atrial dimension 44 +/- 6 mm) with typical isthmus-dependent atrial flutter were studied. The following electrophysiology catheters were used: 20-pole catheter along the tricuspid annulus, quadripolar catheters at the His and/or RV apex, and 8-mm ablation catheter. Following RF ablation of the cavotricuspid isthmus, bidirectional conduction block was confirmed in all 35 patients by pacing at a cycle length of 600 ms from bipoles septal and lateral to the cavotricuspid isthmus ablation line. Conduction times from pacing artifact to adjacent bipolar atrial electrograms and reversal of atrial activation pattern were analyzed. RV pacing was performed and retrograde atrial activation pattern assessed. If retrograde AV nodal conduction was absent, isoproterenol was infused intravenously at 2 microg/min, and RV pacing was repeated. The conduction time between the double potentials across the cavotricuspid isthmus ablation line was measured. RESULTS: Mean conduction times across the isthmus during septal (S), lateral (L), and RV pacing were 145 +/- 21 ms, 144 +/- 24 ms, and 129 +/- 20 ms, respectively. Retrograde AV nodal conduction was present in 34 of 35 patients (isoproterenol 8 patients). Evidence of conduction block by a clear change in activation pattern across the isthmus was seen during RV pacing in 33 of 35 patients with bidirectional conduction block. CONCLUSION: RV pacing is a simple and easy maneuver that can be performed to assess isthmus conduction in most patients.

Atrial Flutter↗
PubMed2006

Reanalysis of the "pseudo A-A-V" response to ventricular entrainment of supraventricular tachycardia: importance of his-bundle timing.

BACKGROUND: The sequence of atrial and ventricular electrograms following termination of ventricular pacing during supraventricular tachycardia has been shown to reliably differentiate atrial tachycardia from atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reentrant tachycardia (AVRT). However in patients with long HV intervals, this may be misleading due to a pseudo "A-A-V" response. The aim of the present study is to see if inclusion of the timing of the His-bundle in the electrogram response (ER) following ventricular pacing would reliably identify the mechanism of tachycardia in patients with long HV intervals. METHODS: Eight patients (7 men) with AVNRT and underlying bundle branch block and long HV (>55 msec) intervals underwent ventricular pacing at 10-40 msec shorter than the tachycardia cycle length during SVT. The ER was classified as "A-A-H" or "A-H" depending on the number of atrial electrograms (A) prior to His deflection following VEP. RESULTS: The ER following ventricular pacing was classified as A-H in all 8 patients. However, using conventional classification the response was A-A-V in 5 of 8 patients due to delayed ventricular activation secondary to long HV intervals and would erroneously suggest atrial tachycardia. The ER was A-V in only 1 of 8 patients. In the remaining 2 patients the A and V electrograms were simultaneous. CONCLUSIONS: Incorporating the His-bundle in the ER following ventricular pacing would eliminate the pseudo "A-A-V" response in patients with AVNRT and long HV intervals. Labeling the response to ventricular pacing as "A-H" or "A-A-H" is simple and more accurate.

Aged↗
PubMed2005

Unusual variant of atrioventricular nodal reentrant tachycardia.

Electrophysiologic study in a patient with supraventricular tachycardia revealed an unusual activation pattern in the coronary sinus (CS) electrodes. Pacing maneuvers confirmed the tachycardia was a slow-slow AV nodal reentrant tachycardia with double potentials in the distal CS electrodes due to an earlier left atrial signal (50 ms) and later CS musculature activation. The left-sided AV nodal inputs were successfully ablated from within the CS.

Cardiac Pacing, Artificial↗
PubMed2005

Dissociation between improvement in left ventricular performance and functional class in patients with chronic heart failure.

Resting left ventricular ejection fraction (LVEF) and functional capacity do not correlate in chronic heart failure patients treated with digitalis, diuretics, and angiotensin-converting enzyme inhibitors. We sought to determine whether substantial improvement in LVEF, as may occur during long-term beta-blockade or after coronary artery bypass graft (CABG) surgery, leads consistently to improvement in functional class. Doppler echocardiogram and assessment of functional class were obtained at baseline and 12 months after initiation of beta-blockade (87 patients) or CABG surgery (51 patients). At 12 months the effects of beta-blockade were variable: LVEF increased greatly by >or=11% (median value) in 45 patients (52%) and by <11% in 19 (22%), but it decreased or remained unchanged in 23 patients (26%). In contrast, functional class was unchanged or worsened in 59 patients (68%) and improved in only 28 (32%). Similarly, surgery had variable effects on LVEF. LVEF increased by >or=12% (median) in 28 patients (55%) and by <12% in 14 (27%), whereas it decreased or remained unchanged in 9 patients (18%). Functional class was unchanged or worsened in 41 patients (80%) and improved in only 10 (20%). Changes in functional class and LVEF were unrelated for both interventions. Both beta-blockade and CABG surgery improve LVEF in the majority of patients. However, significant improvement in LVEF does not enhance functional capacity consistently in chronic heart failure.

Adrenergic beta-Antagonists↗
PubMed2005

Effect of short pulse width programming in AutoCapture devices.

Pacing chronaxie can increase over time. The impact of a short pulse duration on threshold (THR) variations, frequency of noncapture episodes, and overall patient safety has not been fully studied. AutoCapture (AC) pacemakers are capable of memorizing THR trends and loss of capture (LOC) episodes. The study included 20 recipients of AC pacemakers (mean age = 76 +/- 9 years, 15 men) followed for 6 months. They were randomly assigned to pulse durations of 0.2 versus 1.0 ms at 1 month, and crossed over to the alternate programming at 3 months. Evoked response (ER) and AC tests were performed at follow-up. At 0.2 ms and 1.0 ms, the mean number of LOC/day was 2.37 +/- 5.81 and 0.91 +/- 0.49, respectively (ns). LOC trends between follow-up were significantly different with 0.2 versus 1.0 ms pulse duration (P < 0.01). AC THR at 1.0 ms was significantly lower (0.44 +/- 0.77) than at 2.0 ms (0.97 +/- 0.26, P < 0.05). No patient reported symptoms related to LOC during the study. Pulse duration programmed near the strength-duration curve is associated with greater variations in THR and LOC. AC responds to these changes by delivering 4.5 V pulses and keeping the capture THR at low, though safe values.

Aged↗
PubMed2004

Response of pulmonary vein potentials to burst pacing.

BACKGROUND: Pulmonary vein potentials recorded at the ostia of pulmonary veins (PV) are a useful guide for segmental isolation of the PV in patients with atrial fibrillation (AF). Even during coronary sinus pacing at 600 ms, atrial (A) and PV potentials can overlap in 50-60% of patients making the accurate identification of PV potentials very difficult. METHODS: Nineteen patients (M:F 15:4) with paroxysmal AF underwent segmental isolation of one or more PV. Coronary sinus (CS) pacing was performed at cycle lengths of 600/550/500/450/400/350/300 ms and bipolar electrograms were recorded from the 10 or 20 pole Lasso catheter placed at the atrial-PV junction in 27 pulmonary veins. Stimulus (S) to A, S-PVP and A-PVP intervals were measured during CS pacing at the different cycle lengths at sweep speed of 200 mm/sec. RESULTS: During CS pacing at 600 ms the A and PV potentials were significantly overlapped (A-PVP < or = 25 ms) in 15 of 27 (55%) veins. During pacing at 300 ms, the A and PV potentials were significantly separated (A-PVP > or = 25 ms) in 9 of the 15 veins where A and PV potentials overlapped and 21 of all 27 (78%) veins. In two patients pacing at 300 ms was associated with 2:1 conduction block from atrial to PV fascicle. CONCLUSIONS: Coronary sinus pacing at cycle length of 300 ms demonstrated better separation of A and PV potentials compared to pacing at 600 ms. This strategy is easier and less time consuming compared to extrastimuli testing. It also confirms that the electrophysiological properties of PV fascicles are different from that of the adjacent atrial musculature.

Atrial Fibrillation↗
PubMed2002

Runaway pulse generator malfunction resulting from undetected battery depletion.

Runaway pacemaker is an uncommon, potentially lethal circuit malfunction characterized by sudden onset of erratic pacing at rapid nonphysiological rates. Two patients with a single chamber pacemaker (Medtronic ST 8331 and 8419) presented with episodic dizziness. ECG revealed recurrent decrescendo amplitude episodes of runaway stimuli at 2,400 and 2,600 ppm, approximately 3 seconds in duration, separated by pacing at 62.5 and 65 ppm, respectively. Fortunately the runaway stimuli were subthreshold and did not result in capture of the ventricle. Emergency pulse generator replacement was uneventful. Both leads were normal and both pulse generators had low battery voltages at 1.488 and 1.78 V, respectively.

Aged↗