An Investigation into the Electrical Ablation Technique and a Method of Electrode Assessment

Ablative techniques, using standard defibrillators and commonly available cardiac catheters, have been applied to the His bundle and bypass tracts for the management of arrhythmias. We have done in vitro studies of the physical effects of these high energy electrical impulses delivered via different pacing electrodes. Unipolar impulses of 10 to 400 joules were delivered via three U.S.C.I. bipolar electrodes and three Vitatron Helifix electrodes immersed in Ringer's solution. The effects were recorded on 35 mm still film, video tape, and high speed cine film. Pressure, voltage, and current were measured. The U.S.C.I. bipolar electrodes and the Vitatron Helifix electrodes safely withstood repeated delivery of 400-joule impulses which produced similar flash shapes. Each took the form of an incandescent, spherical "fire-ball" centered around the exposed electrode surface. The mean diameters of the "fire-ball" for 10 to 400 J using the U.S.C.I. electrodes were 5-24 mm and 3-20 mm for the Helifix catheter electrodes. Peak pressure excursions of over an atmosphere were observed 3 cm from the electrode tips. Higher pressures, lower voltages, and larger currents occurred using the U.S.C.I. pacing lead. The simple, 35 mm time exposure technique showed that at low energies the flashes appeared to emerge in a retrograde manner from the U.S.C.I. catheters and more distally from the Helifix electrode. This suggested that the latter might be more effective with lower energy impulses. It is concluded that lower energies should be used to take full advantage of the active fixation electrode.     

Measurement of left-ventricular volumes using an internal standard

When performing equilibrium radionuclide angiocardiography with two successive acquisition views, absolute left-ventricular volumes can be calculated using an internal standard generated by a computer in the left-ventricular cavity. The method is based on the computed ratio of maximum to global activity in the 40°-left-anterior-oblique view after background correction and on the measured depth of the left ventricle in almost-orthogonal, 30°-left-posterior-oblique Fourier first-harmonic images. The method does not require blood sampling or correction for self attenuation. The intra- and interobserver reproducibility is excellent, even in patients with severe impairment of the ventricular-contractility pattern. When compared with a classical method requiring venous-blood counting and an attenuation correction factor, the accuracy of the internalstandard method was fairly good, with a regression coefficient of 0.90.     

Ventricular tachycardia as a complication of annular subvalvular ventricular aneurysm in a Caucasian woman

A Caucasian female patient with repetitive attacks of ventriculartachycardia and fibrillation caused by annular submitral leftventricular aneurysm is reported. During a follow-up periodof six years after aneurysmectomy, the patient remained symptom-free.     

Atrial pacing in the management of sick sinus syndrome: Long-term observation for conduction disturbances and supraventricular tachyarrhythmias

Atrial pacing (AAI) in sick sinus syndrome (SSS) has been questionedbecause of the risk of distal conduction disturbances (DCD)and atrial tachyarrhythmias. The authors studied the incidenceof clinically relevant DCD and arrhythmias in 52 SSS patientswith AAI. The observation time was 25–67 (mean 48) months. Invasive electrophysiologic investigation was performed preoperativelyin 29 cases and preoperative atrial pacing to Wenckebach blockor to 150 ppm in 23. The preoperative investigation showed prolongedHV-time in three cases and Wenckebach block at 110ppm in onecase, while six patients had LAH-block, five RBB-block and twofirst degree A V-block. No further DCD developed in any of thesepatients. Second-degree type IA V-block developed in two patientsafter 2 and 19 months, respectively. One had been treated withdigitalis and verapamil and was asymptomatic. The other patient,who had a low ventricular rate, experienced near-syncope. Thesetwo blocks could not be predicted from the preoperative andperoperative investigations. In five patients (10%) permanent atrial fibrillation developedduring the follow-up period. The incidence of concomitant supraventriculartachyarrhythmias in the patients with the bradycardia-tachycardiasyndrome appeared to be unaffected by the pacemaker treatment.     

Dopamine in the conscious dog with chronic heart-block

Summary The chronotropic effects of dopamine were studied in the conscious dog with chronic A-V block. Dopamine at 12.5–200 g/kg and 12.5–50 g/kg/min lowered atrial rate independently of dose. After blockade of muscarine receptors or alpha-adrenoceptors, it raised atrial rate. After blockade of dopamine receptors, dopamine still lowered atrial rate, and did so dose-relatedly after blockade of beta-adrenoceptors. It raised ventricular rate, and at high doses also induced ventricular rhythm disorders. Blockade of muscarine receptors enhanced the ventricular cardioaccelerator effect of dopamine (P<0.025) at 100 g/kg, while blockade of alpha-adrenoceptors reduced it (P<0.05). Blockade of dopamine receptors did not modify this effect, but blockade of beta-adrenoceptors reversed it. Dopamine at 25–200 g/kg raised mean blood pressure. This effect was enhanced by blockade of muscarine receptors, reversed by blockade of alpha-adrenoceptors, and was unaffected by blockade of beta-adrenoceptors or dopamine receptors. These results show that the atrial cardiomoderator effect of dopamine is a vagal reflex response to its hypertensive action, and that it is limited by its direct beta-adrenergic stimulating action. They also show that the ventricular cardioaccelerator effect of dopamine is attenuated by a reflex vagal depressor effect consequent to the induced hypertension. No evidence was found for the existence of positive chronotropic dopamine receptors in either atria or ventricles.A preliminary report of these findings was presented at the Symposium on Peripheral Dopaminergic Receptors, July 1978, in Strasbourg, France (Boucher et al. 1979b)     

室间隔缺损684例外科治疗的回顾分析

目的 :总结 6 84例先天性心脏病室间隔缺损 (VSD)外科治疗的经验、教训及疗效。方法 :自 1988年 6月至 2 0 0 0年 6月收治VSD病人 6 84例 ,其中男性 36 3例 ,女性 32 1例 ,年龄 1 5岁～ 5 0岁 (平均年龄 10 4岁 ) ,其中施行补片 2 46例 ,直接缝合 438例 ;术中采用心脏不停跳下施术 85例。结果 :手术后死亡 6例 ,占 0 88% ;并发完全性房室传导阻滞 9例 ,术后残余分流7例 ,疗效满意。结论 :VSD是一种常见的先天性心脏病 ,根据VSD缺损的不同位置及大小 ,采取不同的手术径路及缝合修补的方法 ;心脏不停跳下VSD修补手术 ,与心脏停跳下VSD修补手术相比 ,不仅降低和防止术后低心排、残余分流等并发症 ,而且避免了心肌的缺血、缺氧和再灌注损伤 ;为了降低VSD合并肺动脉高压病人的死亡率 ,加强围手术期的处理是至关重要的     

急性心肌梗塞Q－T离散度分析－－附68例临床报告

目的：探讨急性心肌梗塞（AMI）患首次心电图Q－T离散度（Q－Td)及Q－Tc离散度（Q－Tcd）与严重室性心律失常发生的关系,对预后进行评估。方法：对68例AMI患首次心电图Q－Td及Q－Tcd进行测定。结果：18例AMI并室速室颤组患Q－Td,Q－Tcd显高于50例非室速室颤组患;结论：AMI患Q－Td及Q－Tcd值增大,室速室颤发生率增加,两呈正相关关系,易发生心源性猝死。故Q－Td及Q－Tcd可作为AMI病情危重预后差的标志,对判断预后有重要临床意义。     

肺静脉血流频谱评价高血压患者的左心室舒张功能

目的　探讨肺静脉血流频谱评价高血压患者左心室舒张功能的价值。　方法　选择 3 0例无心脏疾患者、3 0例高血压无左心房扩大者 ,2 5例高血压左心房扩大者共 85例为研究对象 ,用多普勒超声心动图检测各组肺静脉血流频谱 (PVFP)和二尖瓣血流频谱 (MVFP)参数并做比较。　结果　与正常对照组比较 ,高血压无左房扩大组PVFP中S峰速度加快 ,D峰速度减慢 ,S/D >1 ,AR峰明显加快 ,两组之间有明显差异 (P <0 .0 1 ) ;MVFP中E峰降低 ,A峰增加 ,E峰减速时间 (EDT)延长 ,E/A <1。与正常组对照 ,高血压左心房扩大组PVFP中的S峰降低 ,D峰降低 ,S/D <1 ,但AR峰明显的加速 ,两组之间也有明显的差异 (P <0 .0 1 ) ;MVFP中E峰、A峰、E/A比值和EDT两组近似 (P >0 .0 5 )。　结论　肺静脉血流频谱结合二尖瓣血流频谱能较全面地评价高血压患者的左心室舒张功能。     

Left ventricular mass index and ventricular contractility improvement in patients with severe obesity following rapid weight loss after bariatric surgery

BackgroundObesity is a well-known risk factor for heart disease, resulting in a broad spectrum of cardiovascular changes. Left ventricular mass (LVM) and contractility are recognized markers of cardiac function.ObjectivesTo determine the changes of LVM and contractility after bariatric surgery (BaS).SettingUniversity hospital, United StatesMethodsTo determine the cardiac changes in ventricular mass, ventricular contractility, and left ventricular shortening fraction (LVSF), we retrospectively reviewed the 2-dimensional echocardiographic parameters of patients with obesity who underwent BaS at our institution. We compared these results before and after BaS.ResultsA total of 40 patients met the inclusion criteria. The majority were females (57.5%; n = 23), with an average age of 63.5 ± 12.1. The excess body mass index (BMI) lost at 12 months was 48.9 ± 28.9%. The percent total weight loss after BaS was 16.46 ± 9.9%. The left ventricular mass was 234.9 ± 88.1 grams before and 181.5 ± 52.7 grams after BaS (P = .002). The LVM index was 101.3 ± 38.3 g/m² before versus 86.7 ± 26.6 g/m² after BaS (P = .005). The LVSF was 31% ± 8.8% before and 36.3% ± 8.2% after BaS (P = .007). We found a good correlation between the decrease in LVM index and the BMI after BaS (P = .03).ConclusionRapid weight loss results in a decrease of the LVM index, as well as improvement in the left ventricular muscle contractility. Our results suggest that there is left ventricular remodeling and an improvement of heart dynamics following bariatric surgery. Further studies are needed to better assess these findings.