Publications by authors named "Sumati Ramadas"

4 Publications

  • Page 1 of 1

Programming antitachycardia pacing for primary prevention in patients with implantable cardioverter defibrillators: results from the PROVE trial.

J Cardiovasc Electrophysiol 2010 Dec;21(12):1349-54

Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, Texas, USA.

Objectives: the PROVE trial was designed to determine if antitachycardia pacing (ATP) is clinically beneficial for primary prevention in patients who have implantable cardioverter defibrillators (ICDs) or cardiac resynchronization therapy defibrillators (CRT-Ds).

Background: use of ICDs and CRT-Ds reduces mortality in patients with ventricular dysfunction and mild to moderate heart failure. However, in studies of the primary prevention population, shock-only ICDs are predominantly used, without ATP programming for less painful termination of ventricular tachycardia (VT).

Methods: we conducted a prospective, nonrandomized, multicenter study using market-released ICDs and CRT-Ds. Patients received devices programmed to deliver ATP for VT cycle lengths of 270-330 ms. Follow-up evaluation was performed at 3, 6, and 12 months. The incidence of VT and the rate of successful termination by ATP were analyzed.

Results: of 830 patients in the study population (men, 73%; mean age, 67.3 ± 12 years), 32% received single-chamber ICDs, 44% dual-chamber ICDs, and 24% CRT-Ds. ATP was attempted for 112 VT episodes in 71 patients, and 103 (92%) of the VT episodes were successfully terminated. Three VT episodes were accelerated by ATP and required termination by ICD shock; 6 episodes terminated spontaneously or by ICD shock.

Conclusions: VT is common in patients without a history of this arrhythmia who have received ICDs or CRT-Ds for primary prevention indications. Programming ICDs for ATP therapy at the time of implantation could potentially terminate most VT episodes and reduce the number of painful shocks for these patients.
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December 2010

Long-term changes in high-voltage impedance of defibrillating leads.

Pacing Clin Electrophysiol 2009 Mar;32 Suppl 1:S151-4

Galichia Heart Hospital, Wichita, Kansas, USA.

Background: The maturation of the high-voltage impedance (HVLI) of defibrillating leads has not been explored thoroughly. Since impedance influences the charge, current, and energy delivered to the heart in both fixed pulse-width and fixed tilt implantable cardioverter-defibrillator (ICD) waveforms, changes in HVLI might have an effect on the defibrillation threshold. This analysis examined the maturation of defibrillation lead HVLI.

Methods: The data were collected in 515 recipients of ICDs capable of storing high-voltage shock diagnostics, including HVLI. Data with constant superior vena cava (SVC) coil configuration (coil ON or OFF) were collected for up to 24 months. HVLI values were recorded, plotted, and normalized by the value at implant; the percentage of patients in whom HVLI increased or decreased by > or =6 Omega was calculated, and the maturation of leads with SVC ON versus OFF was compared.

Results: A > or =6 Omega increase or decrease in HVLI was observed in 41% of patients more than 3 months after ICD implant, with the magnitudes as follows: 6-7.5 Omega change = 16%, 8-9.5 Omega= 11%, 10-11.5 Omega= 6%, and > or =12 Omega= 8%. In this subgroup, 67% of patients showed an increase in impedance, and the remaining 33% of patients showed a decrease. For ICD-programmed SVC OFF, the right ventricular (RV) Coil-to-Can HVLI increased by 8 Omega after 6 weeks and did not significantly change thereafter.

Conclusions: HVLI changed significantly in 41% of leads after 3 months. The HVLI trend of the RV Coil-to-Can configuration appeared to be similar to the SVC Coil/Can-to-RV and Coil-to-Can configurations. Changes in HVLI of 6-12 Omega will alter the characteristics of the shock waveform and could require retuning of the waveforms to maintain adequate DFT safety margin. If re-tuning the shock waveforms is not performed, these HVLI changes have the potential to result in elevated DFT. These HVLI changes may partially account for the 15% increase in DFT over time reported in the literature.
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March 2009

Placement of a pacing lead at the inferior portion of the interatrial septum without special tools.

Pacing Clin Electrophysiol 2007 Jan;30 Suppl 1:S84-7

Trinity Medical Center, Rock Island, Illinois, USA.

Introduction: Previous studies have suggested that, among septal sites, the inferior portion of the interatrial septum (IAS) is the most likely to prevent atrial fibrillation, though inserting an active fixation lead at this site can be tedious and time consuming. We describe a relatively straightforward technique to insert a lead at this site without special tools.

Method: We studied 117 consecutive patients (mean age = 76 +/- 8 years, 69% men) with ACC/AHA class I and II pacing indications and histories of paroxysmal or permanent atrial fibrillation, undergoing implantation of a dual chamber pacing system. A technique using the "preshaped" stylet and fluoroscopic guidance is described.

Results: The insertion was successful in 111 patients (95%). Acute dislodgement occurred in six patients (5%). The intrinsic P-wave duration was 117 +/- 22 ms, and the paced P-wave duration was 90 +/- 20 ms (23% shortening, P < 0.001). The mean time required to insert the atrial lead was 12 +/- 8 minutes. No complications occurred.

Conclusions: Insertion of an active fixation lead at the inferior portion of the interatrial septum was safe and highly successful in the majority of patients with this technique.
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January 2007

Transvenous dual site left ventricular pacing plus biventricular pacing for the management of refractory ventricular tachycardia.

J Interv Card Electrophysiol 2006 Oct 17;17(1):73-5. Epub 2007 Jan 17.

Library, Trinity Medical Center, 2701 17th St., Rock Island, IL 61201, USA.

This is a case report of a male patient with nonischemic cardiomyopathy who had severely depressed left ventricular systolic function and functional class III congestive heart failure (CHF). He also had left bundle branch block (LBBB) and recurrent ventricular tachycardia (VT). Though the patient's CFH functional class improved after implantation of a transvenous biventricular ICD system, recurrent VT episodes required the initiation of amiodarone. After an improved condition for 28 months, recurrent VT episodes led to multiple consecutive ICD shocks, which constituted an electrical storm and a battery status of elective replacement indicator (ERI). The recurrent VT episodes were suppressed with intravenous amiodarone and lidocaine. As Radiofrequency ablation was declined by the patient, a new left ventricular (LV) lead was transvenously added, providing biventricular and dual site LV pacing. After this intervention the arrhythmia subsided and the intravenous antiarrhythmic medications were stopped. No episodes of sustained VT leading to ICD shocks were observed for the following 9 months. The events in this case suggest that dual site LV pacing with biventricular pacing could be an alternative strategy for the management of refractory VT.
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October 2006