Biomedical subjects

Darshan Dalal

Publications and source records attributed to Darshan Dalal.

25 records · Page 2Linked to original sources

PubMed2005

Atrial volume reduction following catheter ablation of atrial fibrillation and relation to reduction in pulmonary vein size: an evaluation using magnetic resonance angiography.

INTRODUCTION: Catheter ablation to achieve pulmonary vein (PV) isolation has become an increasingly used treatment strategy for patients with atrial fibrillation (AF). The purpose of this study was to evaluate the impact of segmental isolation of PVs on volume of left atrium and its relation to the decrease in the size of the pulmonary veins. METHODS: Gadolinium enhanced Magnetic Resonance Angiography (MRA) was performed in 51 AF patients before and 6 approximately 8 weeks post PV isolation, using cooled radio-frequency (RF) energy. Three-dimensional reconstruction with maximum intensity projections and multiplanar reformations was performed. Oblique coronal projections were used to measure the ostial size of PVs. Three orthogonal dimensions of LA chamber were measured and computed to assess the volume of the left atrium. RESULTS: The mean LA volume decreased by 15.7% after ablation (p<0.001). The mean PV ostial diameter decreased by 11%, from 18.3+/-0.8 mm to 16.7+/-1.0 mm (p=0.005). Moderate PV stenosis was noted in two veins out of the 192 veins analyzed. There was a significant correlation between changes in the size of PV ostium to that of the LA. CONCLUSIONS: Catheter ablation of AF using a segmental PV isolation approach results in a significant reverse remodeling in the left atrium. Significant stenosis of PVs appears to be rare after the segmental isolation procedure.

Atrial Fibrillation↗

PubMed2005

Safety and efficacy of circumferential pulmonary vein catheter ablation of atrial fibrillation.

OBJECTIVES: The purpose of this study was to report the safety, efficacy, and predictors of recurrence of circumferential pulmonary vein (PV) catheter ablation in patients with atrial fibrillation (AF). BACKGROUND: Circumferential PV ablation has been described as an alternate ablation strategy for AF. METHODS: Seventy consecutive patients (age 56 +/- 10 years) with symptomatic drug refractory paroxysmal (n = 21), persistent (n = 22), and permanent (n = 27) AF underwent catheter ablation. The catheter ablation procedure was performed by creating circular lesions encircling right- and left-side PV ostia guided by an electroanatomic (CARTO) mapping system. Linear ablation lesions also were created in the cavotricuspid isthmus, the mitral isthmus, and in the posterior left atrium. In 42 patients (60%), additions linear lesions were created between superior and inferior PVs in a "figure-of-eight" fashion. RESULTS: At 6 +/- 2.5 months of follow-up, 53 patients (76%) were AF free, including 39 patients (56%) not taking and 14 patients (20%) taking antiarrhythmic drugs. Among various variables, only early recurrence of AF was a predictor of long-term recurrence. Significant complications included one pericardial tamponade, one stroke, and two PV occlusions. Both patients with PV occlusion received radiofrequency delivery in a figure-of-eight fashion. CONCLUSIONS: Circumferential PV catheter ablation of AF is associated with moderate efficacy and risk of complications. The absence of a difference in efficacy combined with the risk of PV stenosis associated with figure-of-eight lesion lead us to conclude that the figure-of-eight lesion should not be a routine component of circumferential PV AF ablation procedures.

Atrial Fibrillation↗

PubMed2005

Predictors of appropriate implantable defibrillator therapies in patients with arrhythmogenic right ventricular dysplasia.

BACKGROUND: Arrhythmogenic right ventricular dysplasia (ARVD) is an inherited cardiomyopathy characterized by ventricular arrhythmias and sudden cardiac death. The risk factors for sudden death and indications for implantable cardioverter-defibrillator (ICD) placement in patients with ARVD are not well defined. OBJECTIVES: The purpose of this study was to determine which clinical and electrophysiologic variables best predict appropriate ICD therapies in patients with ARVD. Particular attention focused on whether the ICD was implanted for primary or second prevention. METHODS: We enrolled 67 patients (mean age 36 +/- 14 years) with definite or probable ARVD who had undergone ICD placement. Appropriate ICD therapies were recorded, and Kaplan-Meier analysis was used to compare the event-free survival time between patients based upon the indication for ICD placement (primary vs secondary prevention), results of electrophysiologic testing, and whether the patient had probable or definite ARVD. RESULTS: Over a mean follow-up of 4.4 +/- 2.9 years, 40 (73%) of 55 patients who met task force criteria for ARVD and 4 (33%) of 12 patients with probable ARVD had appropriate ICD therapies for ventricular tachycardia/ventricular fibrillation (VT/VF; P = .027). Mean time to ICD therapy was 1.1 +/- 1.4 years. Eleven of 28 patients who received an ICD for primary prevention (39%) and 33 of 35 patients who received an ICD for secondary prevention (85%) experienced appropriate ICD therapies (P = .001). Electrophysiologic testing did not predict appropriate ICD interventions in patients who received an ICD for primary prevention. Fourteen patients (21%) received ICD therapy for life-threatening (VT/VF >240 bpm) arrhythmias. There was no difference in the incidence of life-threatening arrhythmias in the primary and secondary prevention groups (P = .29). CONCLUSION: Patients who meet task force criteria for ARVD are at high risk for sudden cardiac death and should undergo ICD placement for primary and secondary prevention, regardless of electrophysiologic testing results. Further research is needed to confirm that a low-risk subset of patients who may not require ICD placement can be identified.

Adolescent↗

PubMed2005

Incidence and predictors of pulmonary vein stenosis following catheter ablation of atrial fibrillation using the anatomic pulmonary vein ablation approach: results from paired magnetic resonance imaging.

INTRODUCTION: There are currently no studies systematically evaluating pulmonary vein (PV) stenosis following catheter ablation of atrial fibrillation (AF) using the anatomic PV ablation approach. METHODS AND RESULTS: Forty-one patients with AF underwent anatomic PV ablation under the guidance of a three-dimensional electroanatomic mapping system. Gadolinium-enhanced magnetic resonance (MR) imaging was performed in all patients prior to and 8-10 weeks after ablation procedures for screening of PV stenosis. A PV stenosis was defined as a detectable (> or =3 mm) narrowing in PV diameter. The severity of stenosis was categorized as mild (<50% stenosis), moderate (50-70%), or severe (>70%). A total 157 PVs were analyzed. A detectable PV narrowing was observed in 60 of 157 PVs (38%). The severity of stenosis was mild in 54 PVs (34%), moderate in five PVs (3.2%), and severe in one PV (0.6%). All mild PV stenoses displayed a concentric pattern. Moderate or severe PV stenosis was only observed in patients with an individual encircling lesion set. Multivariable analysis identified individual encircling lesion set and larger PV size as the independent predictors of detectable PV narrowing. All patients with PV stenosis were asymptomatic and none required treatment. CONCLUSIONS: The results of this study demonstrate that detectable PV narrowing occurs in 38% of PVs following anatomic PV ablation. Moderate or severe PV stenosis occurs in 3.8% of PVs. The high incidence of mild stenosis likely reflects reverse remodeling rather than pathological PV stenosis. The probability of moderate or severe PV stenosis appears to be related to creation of individual encircling rather than encircling in pairs lesion.

Adult↗

PubMed2004

Meta-analysis: high-dosage vitamin E supplementation may increase all-cause mortality.

BACKGROUND: Experimental models and observational studies suggest that vitamin E supplementation may prevent cardiovascular disease and cancer. However, several trials of high-dosage vitamin E supplementation showed non-statistically significant increases in total mortality. PURPOSE: To perform a meta-analysis of the dose-response relationship between vitamin E supplementation and total mortality by using data from randomized, controlled trials. PATIENTS: 135,967 participants in 19 clinical trials. Of these trials, 9 tested vitamin E alone and 10 tested vitamin E combined with other vitamins or minerals. The dosages of vitamin E ranged from 16.5 to 2000 IU/d (median, 400 IU/d). DATA SOURCES: PubMed search from 1966 through August 2004, complemented by a search of the Cochrane Clinical Trials Database and review of citations of published reviews and meta-analyses. No language restrictions were applied. DATA EXTRACTION: 3 investigators independently abstracted study reports. The investigators of the original publications were contacted if required information was not available. DATA SYNTHESIS: 9 of 11 trials testing high-dosage vitamin E (> or =400 IU/d) showed increased risk (risk difference > 0) for all-cause mortality in comparisons of vitamin E versus control. The pooled all-cause mortality risk difference in high-dosage vitamin E trials was 39 per 10,000 persons (95% CI, 3 to 74 per 10,000 persons; P = 0.035). For low-dosage vitamin E trials, the risk difference was -16 per 10,000 persons (CI, -41 to 10 per 10,000 persons; P > 0.2). A dose-response analysis showed a statistically significant relationship between vitamin E dosage and all-cause mortality, with increased risk of dosages greater than 150 IU/d. LIMITATIONS: High-dosage (> or =400 IU/d) trials were often small and were performed in patients with chronic diseases. The generalizability of the findings to healthy adults is uncertain. Precise estimation of the threshold at which risk increases is difficult. CONCLUSION: High-dosage (> or =400 IU/d) vitamin E supplements may increase all-cause mortality and should be avoided.

Adult↗

PubMed2004

Radiation exposure during catheter ablation of atrial fibrillation.

BACKGROUND: The purpose of this study was to determine the radiation exposure during catheter ablation of atrial fibrillation (AF) using the pulmonary vein (PV) approach. METHODS AND RESULTS: The study included 15 patients with AF and 5 patients each with atrial flutter and atrioventricular nodal reentrant tachycardia (AVNRT) who underwent fluoroscopically guided procedures on a biplane x-ray system operated at a low-frame pulsed fluoroscopy (7.5 frames per second). Radiation exposure was measured directly with 50 to 60 thermoluminescent dosimeters (TLDs). Peak skin doses (PSDs), effective radiation doses, and risk of fatal malignancies were all computed. Mean fluoroscopy durations for AF procedures were 67.8+/-21 minutes in the right anterior oblique (RAO) and 61.9+/-16.6 minutes in the left anterior oblique (LAO) projection, significantly different from that required for atrial flutter and AVNRT. The mean PSDs measured with the TLDs were 1.0+/-0.5 Gy in the RAO and 1.5+/-0.4 Gy in the LAO projection. The lifetime risk of excess fatal malignancies normalized to 60 minutes of fluoroscopy was 0.07% for women and 0.1% for men. CONCLUSIONS: The relatively small amounts of the patient's radiation exposure in this study, despite the prolonged fluoroscopy durations, can be attributed to the use of very-low-frame pulsed fluoroscopy, the avoidance of magnification, and optimal adjustments of the fluoroscopy exposure rates. The resulting lifetime risk of fatal malignancy is within the range previously reported for standard supraventricular arrhythmias.

Adult↗

PubMed2004

Electrocardiographic features of arrhythmogenic right ventricular dysplasia/cardiomyopathy according to disease severity: a need to broaden diagnostic criteria.

BACKGROUND: The purpose of this study was to systematically study diagnostic and prognostic electrocardiographic (ECG) characteristics of arrhythmogenic right ventricle dysplasia/cardiomyopathy (ARVD/C). METHODS AND RESULTS: The patient population included 50 patients with ARVD/C (27 males, 23 females; mean age 38+/-15 years). We also analyzed the ECG of 50 age- and gender-matched normal control subject and 28 consecutive patients who presented with right ventricular outflow tract (RVOT) tachycardia. Right bundle-branch block (RBBB) was present in 11 patients (22%). T-wave inversions in V1 through V3 were observed in 85% of ARVD/C patients in the absence of RBBB compared with none in RVOT and normal controls, respectively (P<0.0001); epsilon waves were seen in 33%, and a QRS duration > or =110 ms in V1 through V3 was present in 64% of patients. Among those without RBBB, our newly proposed criterion of "prolonged S-wave upstroke in V1 through V3" > or =55 ms was the most prevalent ECG feature (95%) and correlated with disease severity and induction of VT on electrophysiological study. This feature also best distinguished ARVD/C (diffuse and localized) from RVOT. CONCLUSIONS: A prolonged S-wave upstroke in V1 through V3 is the most frequent ECG finding in ARVD/C and should be considered as a diagnostic ECG marker.

Adult↗