Comparison of Magnetic Navigation System and Conventional Method in Catheter Ablation of Atrial Fibrillation: Is Magnetic Navigation System Is More Effective and Safer Than Conventional Method?

BACKGROUND AND OBJECTIVES: Although there have been so many reports of catheter ablation of atrial fibrillation (AF) with magnetic navigation system (MNS), it is not necessarily obvious that MNS is more effective than conventional ablation. We performed AF ablation with MNS and compared the clinical outcomes and radiofrequency ablation parameters with those of conventional ablation. SUBJECTS AND METHODS: One hundred eleven consecutive patients (conventional group, n=70 vs. MNS group, n=41) undergoing catheter ablation of AF were enrolled. We compared and analyzed the procedural parameters, namely fluoroscopic time, procedural time, acute procedural success and 3 months success rate of both groups. RESULTS: The MNS group was associated with slightly larger left atrial size (43.7+/-6.3 mm vs. 41.2+/-6.3 mm, p=0.04), significantly longer total procedure time (352+/-50 minutes vs. 283+/-75 minutes, p<0.0001), and shorter total fluoroscopic time (99+/-28 minutes vs. 238+/-45 minutes, p<0.0001) than the conventional group. The MNS and conventional group did not differ with respect to acute procedural success, AF recurrence, atrial flutter/atrial tachycardia recurrence, or total arrhythmia recurrence. While no complications were observed in the MNS group, eight cases of significant pericardial effusion occurred in the conventional group. CONCLUSION: The MNS system seems to be effective and safe in the catheter ablation of AF, particularly in the population of patients with persistent AF and slightly dilated left atria.

Transthoracic Echocardiographic Assessment of Adriamycin-induced Cardiomyopathy in Rats with a 15 MHz Transducer

BACKGROUND: Adriamycin (doxorubicin) is one of the widely used drugs in the treatment of a variety of solid and hematologic malignancies. However, the adriamycin-induced cardiomyopathy limits the prolonged use of this effective drug. Transthoracic echocardiography is the excellent tool in early detection and follow-up studies of adriamycin-induced cardiomyopathy. The aim of this study was to assess the cardiac function and morphology using a 15 MHz high-frequency imaging in rats. METHODS: Adriamycin was administrated intraperitoneally by six equal injections at a dose of 2.5 mg/kg over a period of 2 weeks for total cumulative dose of 15 mg/kg body weight in 12 male Sprague-Dawley rats (weight 367+/-39 g). Transthoracic echocardiography with a 15 MHz linear-array transducer was performed at baseline and additionally at 3 weeks to measure the left ventricular wall thickness and dimension from the parasternal short axis view with 2D guided M-mode and pulsed Doppler signals of mitral inflow. Within 2 days of echocardiography, the heart was harvested for electron microscopic evaluation after potassium-induced cardiac arrest. RESULTS: 1) The mortality rate during the experimental period was 0%. 2) Transthoracic echocardiography provided adequate 2D guided M-mode images and pulsed Doppler signals of mitral inflow in all rats. 3) In follow-up echocardiography, pericardial effusion was detected in 7out of 12 rats (58%). 4) Compared to baseline, end-diastolic dimensions were increased from 7.01+/-0.69 to 7.74+/-1.25 mm (p<0.001), end-systolic dimensions were increased from 4.13+/-0.69 to 5.22+/-1.12 mm (p<0.05), and interventricular septal and posterior wall thickness at end-systole and end-diastole were significantly decreased (p<0.05, respectively). 5) Fractional shortening was decreased from 43.0+/-6.8 to 32.7+/-8.0%, compared to baseline (p<0.05). 6) E/A ratio of mitral inflow changed significantly from 1.63+/-0.36 to 2.78+/-1.0, compared to baseline (p<0.05). CONCLUSION: Adriamycin administration at total cumulative dose of 15 mg/kg body weight over 2 weeks creates a reliable model of non-ischemic dilated cardiomyopathy in rats with a high success rate. Transthoracic echocardiography using a 15 MHz transducer provides adequate images for assessing the cardiac function and morphology in follow-up studies in adriamycin-induced cardiomyopathy of rats. These results suggest that transthoracic echocardiography using a 15 MHz Transducer is a promising tool for an assessment of adriamycin-induced cardiomyopathy in small animals.

A Case of Variant Angina Associated with Hyperthyroidism

While angina pectoris is not uncommonly seen in hyperthyroidism, only rare case reports have proved that the myocardial ischemia was induced by coronary artery spasm. A 62 year-old man with a prior diagnosis of hyperthyroidism presented with repeated episodes of syncope and chest pain. The coronary angiogram showed normal coronary arteries. Severe diffuse spasm of both coronary was spontaneously induced and normalized after intracoronary nitroglycerin injection during the procedure of coronary angiography. For one year, he was on simultaneous antianginal and antithyroidal medicines with accomplishment of euthyroid state. He did not experience and anginal symptom for the last six months. The followup coronary angiogram performed 1 year later revealed a newly developed atherosclerotic lesion (about 50% stenosis in diameter) at the proximal left anterior descending artery. However provocative challenge test with intracoronary acetylcholine infusion failed to induce coronary spasm at the lesion. We report a case of coronary artery spasm associated with hyperthyroidism with a review of literatures.

A Case of Single Coronary Artery with Bicuspid Aortic Valve

Single coronary artery is one of coronary artery anomalies, which originates from single aortic ostium and distributes blood to whole myocardium and is reported to occur in about 0.02 percent of general population. Although this condition does not produce severe clinical complications, it is often combined with other congenital cardiac anomaly and may produce angina pectoris, arrythmia, and sudden cardiac death syndrome rarely. Bicuspid aortic valve is anomalous aortic valve which consists of two commisure and two cusps and is said to occur in about 2 percent of the population. In some cases, the valve may function normally for many decades, but in others, it may produce aortic stenosis and/or aortic regurgitation frequently. We report here a case of single coronary artery combined with bicuspid aortic valve.