Background-The use of cardiopulmonary bypass during coronary artery bypass surgery (CABG) has been associated with substantial morbidity. The recent introduction of cardiac stabilizers facilitates CABG without cardiopulmonary bypass (off-pump CABG), but it is unknown whether cardiac outcome after off-pump surgery is similar to that for the on-pump procedure. Methods and Results-In a multicenter trial, 281 patients (mean age 61 years, SD 9 years) were randomly assigned to off-pump or on-pump CABG. In-hospital results and cardiac outcome and quality of life after 1 month are presented. Cardiac outcome was defined as survival free of stroke, myocardial infarction, and coronary reintervention. The mean numbers of distal anastomoses per patient were 2.4 (SD 1.0) and 2.6 (SD 1.1) in the off-pump and on-pump groups, respectively. Completeness of revascularization was similar in both groups. Blood products were needed during 3% of the off-pump procedures and 13% of the on-pump procedures (PϽ0.01). Release of creatine kinase muscle-brain isoenzyme was 41% less in the off-pump group (PϽ0.01). Otherwise, no differences in complications were found postoperatively. Off-pump patients were discharged 1 day earlier. At 1 month, operative mortality was zero in both groups, and quality of life had improved similarly. In both groups, 4% of the patients had recurrent angina. The proportions of patients surviving free of cardiovascular events were 93.0% in the off-pump group and 94.2% in the on-pump group (Pϭ0.66). Conclusions-In selected patients, off-pump CABG is safe and yields a short-term cardiac outcome comparable to that of
Exercise capacity in patients with a LVAD increases over time; 12 weeks after LVAD implantation, Vo2 is comparable to that at 12 weeks and one year after HTx. Previous LVAD implantation does not seem to adversely affect exercise capacity after HTx.
These results suggest that off-pump coronary artery bypass grafting with the Octopus tissue stabilizer is safe. Early clinical outcome and patency rates warrant a randomized study comparing this methods with conventional coronary bypass grafting.
The influence of power and exposure duration on lesion size in radiofrequency catheter ablation was investigated in 15 closed-chest dogs. Radiofrequency energy was delivered to the right ventricular endocardium between the tip of a standard 6F electrode catheter and a large external surface electrode. A total of 102 ablations were performed at power levels of 0.3-9.3 W and durations of 5, 10, 20, 30, and 60 seconds. At necropsy 1 week later, well-demarcated homogeneous lesions were found when power had exceeded a threshold level that decreased from 1.8 W at 5 seconds to 0.7 W at 60 seconds. Lesion size ranged from 0 to 7.5 mm in depth and 0 to 9 mm in diameter. For the 5, 10, and 20 second ablations, lesion size was determined by exposure duration and power level. However, after a 20 second exposure, lesion size had reached maturity and was related to delivered power only. Therefore, a gradual, controlled growth of the lesion can be obtained by a stepwise increase of the radiofrequency power level with ample exposure duration at each level to allow for stabilization. At levels exceeding 7 W, the formation of a thin insulating layer of blood coagulum on the electrode surface caused an abrupt increase of impedance within approximately 30 seconds. Therefore, lesion size is limited to 8.5 mm in radiofrequency ablation with a standard 6F endocardial electrode catheter. (Circulation 1989:80:962-968) C losed-chest endocardial DC shock ablation of conduction pathways and arrhythmogenic sites has been used successfully in patients with cardiac arrhythmias. -6 However, important limitations of this technique, including variability of the size of the ablation lesion at equal energy setting,7 production of a pressure wave,8 proarrhythmic effects,4,5,9-11 and incapability of the catheter to withstand high voltage and current,12,13 warrant further evaluation of other energy sources.By using radiofrequency (RF) alternating current, most of these limitations may be avoided. imity to critical structures like the atrioventricular (AV) node or His bundle. Modification rather than ablation of the AV node may prevent intranodal reentrant tachycardia with preservation of AV conduction. These applications require that the size of the lesion be controllable. However, in the in vivo setting, the relation of lesion size to physical parameters is controversial.14, [19][20][21][22][23][24] In this study, we report the influence of RF power, exposure duration, and delivered energy on lesion extension. Methods AblationFifteen beagles weighing 12-17 kg were anesthetized with methadon:droperidol (20-25 mg i.v.). After endotrachial intubation, ventilation was maintained by a Bird respirator (nitrous oxide:oxygen, 1:1). Anesthesia was maintained by a methadondroperidol mixture. The dogs were placed on their right side, and a large metal electrode covered with conductive gel was positioned underneath the shaved chest.Under sterile conditions, two 6F bipolar USCI electrode catheters were introduced into the right femoral artery and vein and adv...
In an effort to standardize terminology and criteria for clinical electrocardiography, and as a follow-up of its work on definitions of terms related to cardiac rhythm, an Ad Hoc Working Group established by the World Health Organization and the International Society and Federation of Cardiology reviewed criteria for the diagnosis of conduction disturbances and pre-excitation. Recommendations resulting from these discussions are summarized for the diagnosis of complete and incomplete right and left bundle branch block, left anterior and left posterior fascicular block, nonspecific intraventricular block, Wolff-Parkinson-White syndrome and related pre-excitation patterns. Criteria for intraatrial conduction disturbances are also briefly reviewed. The criteria are described in clinical terms. A concise description of the criteria using formal Boolean logic is given in the Appendix. For the incorporation into computer electrocardiographic analysis programs, the limits of some interval measurements may need to be adjusted.
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