Leonard I. Ganz

Implantation success and infection in cardiovascular implantable electronic device procedures utilizing an antibacterial envelope.

Background: u2002Cardiovascular implantable electronic device (CIED) infection rates are increasing faster than implantation rates. More effective antimicrobial prophylaxis may help reduce CIED infections and improve clinical outcomes. The AIGISRx® antibacterial envelope is a polymer mesh implanted in the generator pocket with the CIED. After implantation it releases two antibiotics, minocycline and rifampin, that have been shown to reduce infections associated with other medical devices. The purpose of this retrospective cohort study is to determine the rate of CIED implantation success and CIED infection in procedures utilizing the antibacterial envelope.

Selected patients listed for cardiac transplantation may benefit from defibrillator implantation regardless of an established indication.

BACKGROUNDnEnd-stage heart failure (HF) patients are at high risk of sudden cardiac death. This study evaluates the role of implantable cardiac defibrillators (ICDs) in HF patients awaiting cardiac transplantation.nnnMETHODSnWe identified 194 consecutive patients (age 51 +/- 12 years) with New York Heart Association Class 3 or 4 HF (ejection fraction 22 +/- 9%) listed for cardiac transplantation, 35 of whom underwent ICD implantation. Of the implanted patients, 16 (Group A) had an established indication for ICD implantation (cardiac arrest, n = 10; sustained ventricular tachycardia [VT], n = 3; and positive electrophysiology study, n = 3). Nineteen patients (Group B) underwent ICD implantation for non-established indications (syncope with non-ischemic cardiomyopathy, n = 4; non-sustained VT, n = 15). There were no procedural complications from ICD implantation.nnnRESULTSnDuring follow-up of 9.2 +/- 10.1 months, there were 3 deaths in the ICD groups (A and B), and 40 in the control group (8.6% vs 25.2%, p = 0.032). Five patients in Group A and 6 in Group B (31%) received appropriate ICD therapy. The number of therapies per patient and the time to the first shock were similar between Groups A and B. Four of 6 Group B patients on outpatient inotropic therapy (67%) received appropriate ICD therapy.nnnCONCLUSIONSnSelected end-stage heart failure patients awaiting heart transplantation, including those without established ICD indications, are at high risk for malignant arrhythmias and may benefit from ICD implantation. Patients with ICD seem to have improved survival compared to those without ICD. Randomized prospective studies are needed to confirm these findings.

Utility of Echocardiographic Tissue Synchronization Imaging to Redirect Left Ventricular Lead Placement for Improved Cardiac Resynchronization Therapy

An 80‐year‐old woman with severe symptomatic heart failure (ejection fraction of 13%), and left bundle branch block (QRS duration of 160 ms) underwent cardiac resynchronization therapy (CRT). She had significant baseline dyssynchrony with a septal to posterior wall delay of 160 ms by echocardiographic tissue synchronization imaging (TSI). Despite exhaustive efforts, a stable posterior‐lateral coronary vein lead position could not be achieved with the standard percutaneous approach, resulting in anterior coronary vein lead placement. This resulted in no improvement in the patients symptoms or ventricular function. Follow‐up TSI revealed earlier activation of the anteroseptal site and worsened dyssynchrony with septal to posterior wall delay of now 290 ms. This information prompted surgical revision of the left ventricular (LV) lead position via limited thoracotomy and posterior‐lateral epicardial lead implantation. Pacing at the new lead site resulted in a 30% increase in stroke volume and symptomatic improvement. TSI in this case redirected lead position in a clinical nonresponder, resulting in a favorable response to CRT.

Autonomic Blockade Unmasks Maturational Differences in Rate-Dependent Atrioventricular Nodal Conduction and Facilitation in the Mouse

Maturational Differences in Murine AVN Conduction. Introduction: In large animals, rate‐dependent AV nodal (AVN) properties of conduction are modulated by autonomic inputs. In this study, we investigated whether the properties of AVN conduction and facilitation are altered by autonomic blockade in the mouse and whether this effect is age dependent.

Wide and Narrow Complex Tachycardias: What Is the Mechanism?

December 2001 PACE, Vol. 24 A 49-year-old woman was referred for electrophysiological testing and radiofrequency catheter ablation of recurrent episodes of palpitations of a 10-year duration. The patient had typically been able to terminate the episodes of palpitations with vagal maneuvers until recent months, when they increased in frequency and severity. A 24-hour Holter monitor test showed frequent runs of wide and narrow complex tachycardias, with a recurring pattern of wide complex leading to narrow complex tachycardia of slightly faster rate (Fig. 1). The patient had a full cardiac workup for atypical chest pain and palpitations that included normal stress-thallium test and echocardiogram. During the electrophysiological study, the patient was in sinus rhythm with normal atrio-His (AH) and His-ventricular (HV) intervals of 75 and 50 ms, respectively. The atrioventricular nodal (AVN) Wenckebach cycle length (CL) was 330 ms and the AVN effective refractory period was 200 ms at a drive CL of 600 ms. Ventriculoatrial conduction was observed and the retrograde effective refractory period was 360 ms at a drive CL of 600 ms. With premature atrial stimulation, discontinuous A2H2 versus A1A2 curve was demonstrated. Isoproterenol infusion produced spontaneous runs of wide complex tachycardia that changed into a narrow complex tachycardia at a slightly faster rate. This phenomenon was very reproducible and similar to what was documented on the Holter monitor. What are the mechanisms of the wide and narrow complex tachycardias?

Rhythm classification by correlation-waveform morphology analysis of atrial and ventricular electrogram signals.

We tested the use of correlation‐waveform analysis (CWA) of atrial and ventricular electrograms (EGMs) to distinguish ventricular tachycardia (VT) from supraventricular tachycardia (SVT). Patients undergoing electrophysiologic testing were enrolled. EGMs recorded during induced tachycardias were compared with EGMs recorded during sinus and paced rhythms, taken as templates, by assigning a CWA percent‐match (CPM) score. Twenty‐two patients were studied: 15 men and 7 women (mean age 48 years); 16 with SVT and 6 with VT. Using a sinus‐rhythm template, the atrial CPM scores for SVT and VT were 66%± 20% and 93%± 5%, respectively (P = 0.0034). With a CPM‐score cutoff of 85%, the sensitivity for correctly identifying VT was 100% and the specificity for rejection of SVT was 80%. The corresponding ventricular‐CPM scores for SVT and VT were 81%± 12% and 72%± 24%, respectively (P = 0.13, cutoff = 65%, sensitivity = 50%, and specificity = 90%). Using a ventricular template with atrial pacing, the ventricular‐CPM scores for SVT and VT were 87%± 9% and 76%± 14%, respectively (P = 0.028, cutoff = 70%, sensitivity = 50%, and specificity = 93%). Atrial CWA matching is superior to ventricular CWA matching in discriminating between SVT and VT. CWA matching in both chambers could potentially achieve better discrimination.

Heart Failure and Pulmonary Embolism

Figure 1. Posteroanterior view of the patient’s chest Xray performed 6 months after the pacemaker implantation. The white arrow points to the position of the left ventricular pacing lead upon presentation to the hospital with shortness of breath. orubicin cardiac toxicity presented to the hospital with a one-week history of increasing shortness of breath, dyspnea on exertion, and lower extremity edema. The patient’s past medical history is significant for Hodgkin’s disease diagnosed in the year 2000, currently in remission, severe dilated cardiomyopathy with a left ventricular ejection fraction of 15%, status-post biventricular permanent pacemaker (InSync III Model 8042, Medtronic, Minneapolis, MN USA) implantation in July 2003.

Quantification of acute reduction in mitral regurgitation following cardiac resynchronization therapy

Background: Cardiac resynchronization therapy (CRT) is associated with delayed improvements in cardiac function in heart failure patients with left bundle branch block (LBBB) secondary to reverse remodeling. However, the mechanisms of immediate benefits from CRT pacing are not well understood. Our objective was to assess the acute effects of CRT pacing on mitral regurgitation (MR) using quantitative volumetric Doppler echocardiography. Methods: Twenty-four HF patients with LBBB, aged 66 10 yrs, with ejection fraction of 25 7% and QRS duration of 168 35 ms were studied by quantitative 2-D and Doppler echocardiography at baseline and the day after CRT biventricular pacing therapy. MR was quantified with the volumetric method and expressed as regurgitant volume and regurgitant fraction, in addition to and digital color regurgitation jet area. MR regurgitant volume was obtained by subtracting left ventricular outflow tract stroke volume from mitral inflow stroke volume, determined by their respective time velocity integrals multiplied by cross-sectional area. MR regurgitant fraction was obtained by dividing regurgitant volume by mitral inflow stroke volume. Results: Baseline group mean MR regurgitant volume was 35 24 ml, MR regurgitant fraction was 35 17% and MR jet area was 6.9 4.9 cm. After only 23 10 hours of CRT, significant improvements in MR occurred with regurgitant volume decreasing to 20 19 ml* and MR regurgitant fraction decreasing to 21 16%*, (*p 0.01 vs. baseline) (figure). MR jet area also decreased to 5.0 5.1 cm (p 0.05 vs. baseline). Acute reductions in MR were accompanied by a significant improvement in cardiac index from 2.1 0.5 to 2.4 0.6* L/min/m (*p 0.05 vs. baseline). Conclusion: CRT resulted in acute significant reductions in MR and increases in cardiac index. These data support MR reduction as an important acute beneficial effect of CRT in HF patients with LBBB.