ISSN:0009-7322    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

SUMMARYSurvivors of out-of-hospital ventricular fibrillation (VF) are at high risk for recurrent VF, probably reflecting continued myocardial electrical instability. In this study 12-lead ECGs of 125 VF survivors with coronary heart disease were examined and compared to those of 98 ambulatory post-MI patients. The study was part of an effort to define clinical identifiers of patients likely to develop sudden cardiac death. Ventricular fibrillation survivors more commonly had premature ventricular complexes (PVCs): 30% versus 13% (P < 0.01). In addition, ECGs of VF survivors showed a significantly greater prevalence of ST-segment depression (46% versus 10%), T wave flattening (52% versus 26%), and QT, prolongation (35% versus 18%). It is proposed that these repolarization abnormalities represent asynchronous repolarization, which together with frequent PVCs, may set the stage for re-entrant ventricular dysrhythmias and ultimately VF. It is also possible that repolarization abnormalities together with premature ventricular contractions might serve as markers of patients with coronary heart disease who are at increased risk for sudden cardiac death.

ISSN:0009-7322    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

SUMMARYAlthough the mechanism of most episodes of recurrent ventricular tachycardia (VT) is believed to be re-entry, definitive proof of this hypothesis has heretofore been unavailable in man. Using programmed stimulation and ventricular endocardial mapping we studied three patients in whom the initiation of VT was dependent upon developing a critical degree of fractionation and delay in local left ventricular electrograms. When electrical activity spanned diastole, VT ensued. Maintenance of VT was associated with continuous electrical activity resembling "local fibrillation" while termination of VT required cessation of this continuous activity. During sinus rhythm the electrogram recorded from the areas which subsequently developed continuous activity showed markedly fractionated and prolonged electrical activity exceeding 100 msec in duration. We feel these observations of the temporal relationship of continuous activity with the development of VT represent the first documentation of the re-entrant nature of this arrhythmia in man.

ISSN:0009-7322    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

SUMMARYThe adequacy of intraoperative epicardial mapping as a guide to surgical procedures performed to terminate ventricular arrhythmias was investigated. Ligation of the anterior septal or left anterior descending coronary artery in 28 dogs produced ventricular arrhythmias that were studied 24-36 hours following occlusion. The sites of origin of 26 tachycardias were determined to be in the subendocardium by using extensive epicardial, endocardial and intramural mapping techniques and were verified by demonstrating unaltered activation sequences during pacing from these earliest sites.Epicardial breakthrough followed earliest directly recordable ven- tricular activity by as little as 7 msec. Without endocardial mapping many of these tachycardias would have been incorrectly identified as originating in the fascicles or epicardium. The sites of epicardial breakthrough were anatomically distant from the sites of origin by a markedly varying extent (5 mm to 6 cm). Two rhythms might be close in their sites of earliest epicardial appearance yet distant on the endocardium or vice versa.We conclude that epicardial mapping may not be sufficient to identify or predict the origins of many ventricular tachycardias and that the success of surgery to abolish these arrhythmias may be enhanced by preoperative and intraoperative endocardial mapping.

ISSN:0009-7322    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

SUMMARYForty-five patients with the Wolff-Parkinson-White syndrome and reciprocating tachycardia which utilized the atrioventricular (A-V) node for antegrade conduction and an accessory pathway for ventriculo-atrial (retrograde) conduction were studied. The extrastimulus technique in the right atrium and coronary sinus at multiple pacing cycle lengths was used. Three types of "echo zones" were defined by the relationship of the antegrade effective refractory period (ERP) of the accessory pathway, the longest coupling interval accompanied by an atrial echo, the ERP of the A-V node, and the functional refractory period of the atrium. Eighteen of 45 patients (40%) had more than one type of echo zone demonstrated by changing either pacing site or pacing cycle length or both. Pacing site and in- traventricular conduction delay were found to have important effects on the longest coupling interval accompanied by an atrial echo in those echo zones in which the longest coupling interval accompanied by an atrial echo was less than the antegrade ERP of the accessory pathway.The echo zone is a useful concept to explain the physiology of the common reciprocating tacbycardia in patients with the Wolff- Parkinson-White syndrome. However, the echo zone is profoundly affected by pacing site and pacing cycle length. When these variables are changed, many patients can be shown to have more than one type of echo zone. Studies of the echo zone have limited value as therapeutic guides.

ISSN:0009-7322    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

SUMMARYThe risk of advanced atrioventricular block during anesthesia was studied prospectively in 44 patients with right bundle branch block and left axis deviation who underwent a total of 52 operations over a 14 month period. All patients had continuous electrocardiographic monitoring throughout anesthesia induction, operation, and surgical recovery. Of the 52 operative procedures, 24 were done under general anesthesia, 11 under spinal, and 17 under local. The preoperative cardiac rhythms were atrial fibrillation in two patients, atrial tachycardia with block in one patient, atrial flutter in one patient, and sinus rhythm in the remaining patients. Temporary pacemakers were inserted preoperatively in six patients, usually because of PR interval prolongation on the preoperative electrocardiogram. There was only one episode of transient complete heart block in 51 of the 52 operative procedures. In two of the six patients with temporary pacemakers, significant pacer-related ventricular irritability occurred. This study indicates that temporary pacemaker insertion is rarely required in patients with chronic right bundle branch block and left axis deviation who require noncardiac surgery.

ISSN:0009-7322    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

SUMMARYTo study the action of aspirin upon the myocardium per se, independent of thrombosis, coronary occlusion with a balloon catheter was induced in 53 anesthetized dogs divided into two groups. One group (N = 20) was treated daily with aspirin (600 mg/dog) for seven days and another (N = 33) was untreated. Left ventricular hemodynamics and precordial ECG mapping were used to assess the influence of myocardial ischemia over a four hour period. There were no significant differences in left ventricular function or extent of injury as judged by ECG mapping between the two groups. However, there was a significant decrease in the incidence of ventricular fibrilla- tion in the treated dogs (5% vs 39%). Serial plasma samples for free fatty acid determination showed a significant rise in the untreated group. Aspirin blocked the FFA increment in the treated animals. Tissue samples from the ischemic area of left ventricle exhibited a significant reduction of the sodium and water increments, as well as a lesser potassium loss in the treated animals compared to the controls and may have been the basis for the lower incidence of arrhythmias. Since infusion of 51Cr labelled platelets showed no myocardial accumulation of platelets in either group, microthrombi did not appear to contribute to the observed differences.

ISSN:0009-7322    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

SUMMARYThe electrophysiologic properties of tocainide were evaluated by electrophysiologic studies in 11 patients before, during and after a constant intravenous infusion of the drug for 15 minutes. Peak plasma tocainide concentrations averaged 11.0 ± 1.7 Ag/ml (sEM), range 3.7 to 22.7. AH, HV, QRS, QTc and RR intervals were measured every 5 minutes during sinus and atrial-paced rhythms and showed small changes which were not statistically significant for HV and QRS. Mild shortening of RR was significant (P < 0.05) at 15 minutes only. AH tended to increase slightly for spontaneous (but not paced) rhythm, becoming significant at 15 minutes only (P < 0.05). QTc decreased slightly, a change which was significant (P < 0.05) for paced but not spontaneous rhythm. A progressive rise in mean arterial pressure occurred during drug infusion and persisted through 30 minutes (P < 0.001). Comparison of electrophysiologic studies at 0 and 30 minutes showed decreases in mean effective refractory periods of atrium. A-V node. and rieht ventricle by 17, 22, and 23 msec, respectively (P < 0.05, 0.01, 0.01). Functional refractory period of the A-V node showed an average 4ecrease which was not significant. Sinus node recovery time and Wenckebach cycle length were unchanged. The drug was well tolerated in all 11 patients. Hypotension in a twelfth patient may or may not have been drug related. These results obtained at therapeutic plasma concentrations suggest qualitative similarities between the conduction system effects of tocainide and those published for lidocaine.

ISSN:0009-7322    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

SUMMARYLeft ventricular (LV) apexcardiogram (ACG) and its first derivative (dA/dt) was obtained in 104 normal subjects and 34 patients with chronic aortic incompetence (Al). In the patients with Al the ACG was recorded simultaneously with LV pressure (tipmanometer). The systolic upstroke time (SUT), the time to peak dA/dt (t-dA/dt) and the a wave percentage amplitude (a/H) of the ACG were measured. In normal subjects SUT averaged 99 ± 17 (SD) msec. In 17 patients with Al and normal ejection fraction (EF) (group 1) SUT was within normal limits; in 17 patients with Al and decreased EF (group 2) it was prolonged (142 ± 19 msec) (P < 0.001). The SUT was closely correlated with EF (r= -0.85) and less with contractile indexes derived from pressure curves. The indexes t-dA/dt and a/H were not significantly different in groups I and 2; they were weakly correlated only with the time to peak rate of LV pressure rise (r= +0.56) and the LV end-diastolic pressure (r= +0.59), respectively.These results demonstrate the superiority of SUT over the other apexcardiographic parameters. The measure provides another means of noninvasive assessment of the LV performance in patients with Al.

ISSN:0009-7322    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

SUMMARYThe accuracy of determining left ventricular function from echocardiography was assessed in 26 children (group I) with cineangiographically-determined normal left ventricular volume (LVV) and 28 children (group II) with large left ventricular volumes. Conventional LV echo dimensions were compared to the cineangiographic LV anterior-posterior minor axis (LVmA) and LVV. Very good correlations were found in group I between LV enddiastolic echo dimensions (LVEDD) and cine LVmA (r= 0.91) and between LVEDD and LV end-diastolic volume (LVEDV) by cine in group I (r= 0.86). In group II correlations were less accurate between LVEDD and diastolic LVmA and between LVEDD and LVEDV. There was poor correlation between the cine and echo percent of shortening (r= 0.41) and velocity of circumferential fiber shortening (VCF) (r= 0.51). This study demonstrates that M-mode echocardiography is a very useful method for determining LV dimensions in children with normal LV volume, but is less accurate in children with left ventricular volume overload or with abnormal septal orientation or postoperative status after ventriculotomy.

ISSN:0009-7322    

出版商:OVID    

年代:1978

数据来源: OVID