Biomedical subjects

Mitchell Faddis

Publications and source records attributed to Mitchell Faddis.

4 recordsLinked to original sources

PubMed2006

Remote controlled magnetically guided pulmonary vein isolation in canines.

BACKGROUND: Ablation of atrial fibrillation (AF) remains a challenging procedure fraught with significant risks and technical difficulties. A magnetically guided catheter system has been developed that potentially addresses many of these challenges. Fully remote controlled electrical isolation of pulmonary veins was performed in canines, facilitated by a three-dimensional computed tomogram (CT) that depicted the anatomic relationships of the pulmonary veins and the left atrium. OBJECTIVE: The purpose of this study was to evaluate the feasibility of pulmonary vein isolation with a novel remote controlled magnetically guided catheter. METHODS: CT scans were obtained in seven healthy male canines. A 7-Fr irrigated magnetic catheter was advanced transseptally to the left atrium. A magnetic guidance system was used to control the orientation of the catheter tip. A mechanical device advanced or retracted the catheter as needed. Pulmonary venography was performed and compared with the CT scan. The CT scan was used as a visual reference to set the magnetic field vectors. Radiofrequency energy was delivered through the irrigated magnetic catheter to isolate the superior pulmonary veins, as judged by elimination of pulmonary vein potentials. RESULTS: The isolation procedure was successful in all 14 pulmonary veins, and there was no evidence of stenosis at 80-100 days postprocedure. CONCLUSIONS: These results demonstrate that remote controlled catheter ablation is safe and effective for segmental pulmonary vein isolation. This technology could facilitate curative ablation of AF in humans and reduce the occupational hazards to the operator of prolonged procedures and radiation exposure.

Animals↗

PubMed2006

Defibrillation energy requirements in an ICD population receiving cardiac resynchronization therapy.

OBJECTIVES: While defibrillation energy requirements (DERs) have been extensively studied in patients receiving conventional defibrillators, the DERs of patients receiving cardiac resynchronization therapy with defibrillation capability (CRT-D) devices have not been well described. The purpose of this analysis was to characterize DERs (defined as true threshold or the presence of appropriate safety margins) in patients undergoing implant of a CRT-D and to determine whether DERs in this population were similar to those reported for patients undergoing implantation of conventional defibrillators. METHODS: Data were analyzed retrospectively from the VENTAK CHF/CONTAK CD biventricular pacing study. An appropriate safety margin of at least 10 J was verified with at least two successful conversions with 21 J or less. Multivariate logistic regression was performed to determine baseline predictors of failed DER testing. RESULTS: Of 501 patients enrolled, 444 (89%) had successful DER test outcomes. Of the remaining 57 patients, 34 converted with energies > or = 21J, and 23 had their testing terminated prematurely or were not tested, primarily due to patient condition. Larger left ventricular internal dimension in diastole (P = 0.003) and prolonged procedure time (P = 0.01) were significant predictors of higher energy requirements. Few significant complications arose from DER testing. CONCLUSIONS: DER testing can be accomplished safely and successfully in the majority of CRT-D patients. However, safety margins cannot be ascertained in a significant number of these patients. Left ventricular inner diameter in diastole (LVIDd) and prolonged procedure time may predict higher DERs, and could be used to anticipate the need for a high-energy device or inclusion of a subcutaneous array.

Aged↗

PubMed2004

Long-term retention of cardiac resynchronization therapy.

OBJECTIVES: The purpose of this study was to determine the frequency and causes of intermittent and permanent loss of cardiac resynchronization therapy (CRT) in patients who have undergone the successful implantation of a transvenous defibrillator that delivers CRT (CRT-D). BACKGROUND: The causes of loss of CRT have not been described. METHODS: The records of 512 patients who underwent an attempt at implantation of a transvenous CRT-D device as part of the VENTAK CHF/CONTAK CD Biventricular Pacing study were analyzed. RESULTS: Device implantation was successful in 443 of 512 (87%) of patients. Among these 443 patients, CRT was interrupted in 161 (36%) patients during a mean follow-up of 2.5 +/- 1.1 years. Reasons included the development of an atrial tachyarrhythmia (18%), loss of left ventricular capture (10%), diaphragmatic stimulation (2%), loss of right ventricular capture (2%), infection (1%), intentional discontinuation of CRT (1%), loss of right atrial sensing (1%), and ventricular oversensing (0.2%). Most patients underwent an intervention that permitted the reinstitution of CRT, such that only 20 of the 443 patients (5%) experienced the permanent loss of CRT. Using an intention-to-treat analysis, the long-term retention of CRT was 83% during the course of 2.5 years. CONCLUSIONS: Cardiac resynchronization therapy is interrupted in more than one-third of patients after the successful implantation of a CRT-D device. However, CRT can be reinstituted in most patients and has a high long-term retention rate. Because patients with slower heart rates were more likely to develop atrial tachyarrhythmias, a dual-chamber rate-modulated pacing mode (DDDR) may reduce interruptions of CRT.

Aged↗

PubMed2002

Resynchronization Therapy for Congestive Heart Failure.

Ventricular contraction is achieved by the coordinated electrical activation of the ventricles through the action of the cardiac conduction system. In the presence of left bundle branch block (LBBB) or interventricular conduction delay (IVCD), the ventricular contraction pattern is desynchronized and the stroke volume is reduced as a consequence. In patients with congestive heart failure (CHF) due to systolic dysfunction, the presence of LBBB or IVCD further degrades ventricular function, contributing directly to the severity of their CHF symptoms. Cardiac resynchronization therapy (CRT) through biventricular pacing relieves CHF symptoms and improves functional status in patients with medically refractory heart failure due to left ventricular systolic dysfunction and LBBB or IVCD. The benefits of CRT are due to improvement in the ventricular activation sequence, resulting in a more coordinated and efficient ventricular contraction. In addition to symptomatic benefits, available data support the hypothesis that CRT alters the natural history of CHF in patients with intraventricular conduction delay.

Journal Article↗