摘要:

ABSTRACTIt is now well established that the vulnerability of the ventricular myocardium to repetitive dysrhythm increases in the presence of greater than normal disparity of local recovery times. Local recovery is reflected in the electrocardiographic waveform as an area of the ventricular deflection (QRST time integral), and thus disparate ventricular recovery may be manifested in the body surface distribution of this quality. To assess this possibility, we obtained simultaneous 120-lead electrocardiograms from both the anterior and posterior torso in 140 subjects (ages 8 to 75) grouped as follows: group A, 97 normal subjects; group B, 16 patients resuscitated from ventricular fibrillation or sustained ventricular tachycardia; and group C, 27 patients 6 to 12 months after myocardial infarction but without clinically significant arrhythmia. In each subject, the QRST integral was evaluated for each lead and isointegral contour maps were plotted. A score was assigned to each map, based on the number of extrema; each maximum or minimum scored one point, with the exception of simultaneously occurring anterior and posterior minima on the right shoulder (frequently occurring in normal subjects), which scored together only one point. All but one group A subject had dipolar QRST integral maps (mean + SD score 2. 11 ± 0.2). Conversely, 10 of 16 (62.5%) group B patients had scores of 3 or more (mean 3.16 + 1.08; p < .01 vs group A). Group C patients had intermediate values, with eight of 27 (29.6%) scoring 3 or more (mean 2.46 + 83); this was less than in group B (p < .01), but more (p < .05) than in group A. Thus, patients with repetitive ventricular arrhythmia tend to have multipolar distributions on QRST integral maps, possibly reflecting dispersion of underlying properties of ventricular recovery. These results suggest that body surface potential mapping may provide a noninvasive means to detect substrate for life-threatening arrhythmias.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTTo determine if anodal excitation during bipolar stimulation facilitates the initiation of sustained monomorphic ventricular tachycardia, nonsustained polymorphic ventricular tachycardia, or repetitive ventricular responses, both bipolar and cathodal unipolar programmed ventricular stimulation with one to three extrastimuli delivered during ventricular pacing at two rates from the right ventricular apex were performed in 28 patients evaluated for spontaneous sustained ventricular tachycardia or ventricular fibrillation (11 patients), nonsustained tachycardia (eight patients), or syncope (nine patients). In 25 patients a hexapolar pacing catheter was used to record local endocardial activation times adjacent to the cathode and anode and ventricular excitation during bipolar stimulation was defined as predominantly anodal, cathodal, or simultaneous at both anode and cathode. When bipolar and unipolar stimulation were compared there was no difference in the incidence of initiating sustained monomorphic ventricular tachycardia (57% vs 57%), nonsustianed polymorphic ventricular tachycardia (14% vs 14%), or repetitive ventricular responses (21% vs 2 1%), although the response to bipolar vs unipolar stimulation was not concordant in every patient. Evidence of anodal excitation was observed in 11 (44%) patients but did not indicate increased risk of initiation of any ventricular arrhythmia, despite the fact that it was associated with shortening of the ventricular effective refractory period by 5.2 8.7 msec (p < .05) during bipolar as opposed to unipolar stimulation. We conclude that unipolar and bipolar stimulation produce a similar incidence of initiation of arrhythmia, despite the frequent occurrence of anodal excitation during bipolar stimulation. Thus, the risk of initiation of nonspecific ventricular arrhythmias during programmed stimulation is unlikely to be reduced by the use of unipolar stimulation.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTAutomatic external defibrillators (AEDs) may have advantages over manual defibrillation in managing prehospital cardiac arrest, particularly in rural communities. We conducted a two-part evaluation of a commercially available AED. We first established the diagnostic accuracy of the AED's rhythm recognition algorithm by challenging it with 205 cardiac arrest rhythms previously recorded from actual patients in the field. The AED demonstrated 100% specificity and 92% sensitivity for ventricular fibrillation (VF) in this nonclinical setting. We then compared the clinical efficacy of AEDs in 18 small communities (study group) with that of manual defibrillation in 18 additional communities (control group) of similar size. Ambulance technicians using manual defibrillators correctly diagnosed VF more frequently than the AEDs (98% vs 83%; p <.025). Specificity for VF was similar in the two groups (100% for AEDs vs 94% for technicians; p > .10). AEDs were able to deliver shocks more quickly than was possible with the manual defibrillators (1.56 vs 2.77 min; p <.001). The ability of the AEDs to terminate VF was excellent, converting VF in 28 of 29 (97%) patients to some other rhythm compared with only 37 of 53 (70%) patients in the control group (p < .01). Hospital admission and discharge rates were similar for the two groups. Ten of the 35 (29%) patients managed with AEDs achieved admission and six (17%) were ultimately discharged. In the control group 17 of 53 (33%) patients with VF were admitted and seven (13%) were discharged (p > .75). AEDs are an effective alternative to manual defibrillation in small communities.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTTo determine risk factors for restenosis, we studied 998 patients who underwent elective coronary angioplasty (PTCA) to native coronary arteries between July 1980 and July 1984. Restenosis, defined as a luminal narrowing of greater than 50% at follow-up, was present in 302 patients (30.2%). Univariate analysis of 29 factors revealed seven factors related to restenosis: vessel dilated (circumflex coronary artery 18%, right coronary artery 27%, left anterior descending artery 34%; p <.01), final gradient of 15 mm Hg or less compared with greater than 15 mm Hg (27% vs 38%, p <.01), duration of angina greater than 2 months compared with angina of shorter duration (27% vs 35%, p = .01), post-PTCA stenosis of 30% or less compared with 31% to 50% (28% vs 36%, p <.025), stable vs unstable angina (26% vs 34%, p <.05), presence vs absence of intimal dissection (26% vs 32%, p = .07), and female gender vs male gender (25% vs 32%, p = .08). Multivariate analysis revealed five factors independently related to increased risk of restenosis in the following order of importance: PTCA in the left anterior descending artery, absence of intimal dissection immediately after PTCA, final gradient greater than 15 mm Hg, a large residual stenosis after PTCA, and unstable angina. Restenosis after PTCA is a multifactorial problem. The hemodynamic and angiographic result at the time of PTCA significantly influences long-term outcome, but additional measures aimed at reducing the rate of recurrence of atherosclerotic plaque are required.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTThis was a prospective, placebo-controlled, single-blind trial of moricizine (ethmozine) in a dose averaging 10 mg/kg/day in 50 patients, the single entrance criterion being the presence of lO or more runs of nonsustained ventricular tachycardia (VT) on a screening 24 hr ambulatory electrocardiographic (ECG) recording. Electrophysiologic study was not included as part of this trial design. The placebo frequency of VT (average 3 days of recording) was 1036 + 479 runs of VT per day. Most patients (31/50) had coronary artery disease. The study population had a mean left ventricular ejection fraction (LVEF) of 36 ± 16%; 20 patients also had a history of sustained VT. Protocol failure was defined as failure to achieve a 75% or greater reduction in runs of VT (as judged by ambulatory ECG recording) and/or recurrence of sustained VT while on moricizine. Among the 48 patients treated with moricizine, the drug was initially efficacious in 35 (73%), with two-thirds having total abolition of nonsustained VT. Although it was effective in reducing runs of nonsustained VT, moricizine was ineffective in preventing the recurrence of sustained VT (63% failure rate). Side effects were uncommon and the drug was well tolerated in most patients with LVEFs of 30% or less.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTIn 16 patients undergoing angioplasty of the left anterior descending coronary artery, the clinical, electrocardiographic, and hemodynamic effects of short-term intravenous nonselective,Badrenergic blockade with propranolol (0.1 mg/kg) were assessed during temporary occlusion of the artery. Myocardial ischemia during coronary occlusion was prevented, delayed in onset, or diminished in magnitude by propranolol in 10 of the 16 patients. Propranolol decreased values for indexes of myocardial oxygen demand, such as heart rate and blood pressure and their product, in all patients. Surprisingly, in patients who derived clinical benefit, propranolol did not change indexes of myocardial oxygen supply to the left ventricular region perfused by the occluded artery. For example, great cardiac vein flow (40 ± 15 to 41 ± 17 ml/min, p = NS) and coronary collateral resistance (2.1 .0 to 2.1 + 1.1 mm Hg/mi/min, p = NS) were unchanged. In contrast, a worsening of supply occurred in patients who were not benefited: great cardiac vein flow (50 ± 10 to 39 + 6 ml/min, p <.05) decreased and coronary collateral resistance (1.6 ± 0.5 to 2.0 + 0.6 mm Hg/ml/min, p <.05) increased. Information obtained from this study demonstrates the value of this new experimental preparation in helping assess potential clinical effectiveness of drug interventions during the initial phase of acute coronary occlusion and providing insight into the mechanisms of drug effect.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTThe goal of this study was to verify whether myocardial protection could be achieved via the intracoronary administration of propranolol in patients undergoing percutaneous transluminal coronary angioplasty (PTCA). Accordingly, 21 patients undergoing PTCA were randomly assigned to receive either intracoronary placebo (group A, n = 10) or intracoronary propranolol (group B, n = 11). Three balloon inflations (i.e., coronary artery occlusions) were performed in each patient. Inflations I and II (maximum duration 60 sec) served as control occlusions. Inflation III (maximum duration 120 sec) was performed either after intracoronary administration of saline (2 ml) or propranolol (1.1 + 0.2 mg). The following electrocardiographic index of myocardial ischemic injury were measured: (1) time to the development of ST segment elevation equal to 0.1 mV and (2) magnitude of ST segment elevation after 60 sec of coronary artery occlusion. Both indexes did not differ significantly between the groups during inflations I and LI. In group A the time to development of ST segment elevation of 0.1 mV remained unchanged between the second and third occlusions (25 + 5 and 26 ± 4 sec during inflations II and III, respectively). In group B subselective injection of propranolol into the affected coronary artery significantly prolonged the time to ST segment elevation of 0. 1 mV from 19 + 4 sec (inflation II) to 53 ± 9 sec (inflation III; p <.001). Administration of placebo did not change the magnitude of ST segment elevation 60 sec after coronary artery occlusion between the second and third occlusion in group A (0. 16 + 0.02 and 0. 18 ± 0.03 mV, respectively). In group B, after intracoronary administration of propranolol, ST segment elevation 60 sec after occlusion decreased significantly from 0.23 0.06 mV (inflation II) to 0.12 ± 0.04 mV (inflation III; p <.005). There were no significant differences in heart rate and mean aortic pressure between groups A and B during inflations I, II, and III. In conclusion, our results suggest that (1) repetitive episodes of transient coronary artery occlusion are associated with similar degrees of myocardial ischemic injury, (2) intracoronary propranolol significantly reduces the electrocardiographic indexes of myocardial ischemic injury, and (3) the myocardial protection afforded by intracoronary propranolol is most likely mediated by a regional effect of the drug.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTN-Methyldopamine (epinine), one of the few modifications of the dopamine (DA) molecule that retains agonist activity at the DA, receptor, was administered orally as the diisobutyric ester, ibopamine (100, 200, and 300 mg), to 15 patients with congestive heart failure. An increase in cardiac index and decline in systemic vascular resistance was observed with each dose, and these hemodynamic effects persisted for 3 to 6 hr. Small transient increments in right atrial and pulmonary capillary wedge pressures occurred 0.5 hr after ingestion of 200 and 300 mg of ibopamine, but these pressures returned to baseline or lower levels within 30 min. Heart rate and mean arterial pressure were unchanged. Plasma concentrations of epinine peaked 0.5 hr after administration of drug and then declined to minimal levels at 3 hr. Ten patients enrolled in a trial to evaluate the efficacy of long-term therapy with ibopamine; after 8 weeks of treatment, the initial hemodynamic responses to the drug were attenuated and no significant improvement in oxygen uptake at peak exercise was observed. A decline in plasma norepinephrine concentrations, which could be attributed to activation of a2-adrenoceptors and/or DA2 receptors on sympathetic nerves, was observed after initial administration of ibopamine and persisted after long-term drug ingestion; no long-term hemodynamic benefit could be ascribed to the reduction in sympathetic activity.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTHemorrhagic acute myocardial infarction (AMI) was studied after selective intracoronary thrombolysis (SICT) in 30 patients undergoing autopsy. Urokinase, 240,000 to 1,200,000 U, was selectively injected into the infarct-related coronary artery at 2 to 9 hr (4 2 hr) after the onset of AMI. The infarct-related coronary artery showed complete occlusion in 21, 99% stenosis in eight, and 90% stenosis in one patient before SICT. After SICT, complete occlusion was seen in only five, 99% stenosis in 22, and 90% stenosis in three patients. Twenty-eight patients had transmural infarction and the other two had subendocardial infarction. Macroscopically and microscopically, the degree of hemorrhage was classified as no, slight, moderate, or marked bleeding and the hemorrhagic infarction was defined as moderate or marked diffuse bleeding in the infarct area. According to the interval from SICT to death, patients were also classified into stage I (early acute stage, 1 to 4 hr after SICT and 4 to 13 hr after the onset of AMI; n = 7), stage IL (late acute stage, 9 hr to 1 1 days after SICT and 15 hr to 1 1 days after the onset of AMI; n = 18), or stage 111 (old infarction stage, over 17 days after AMI and SICT; n = 5). There were no significant differences with respect to the frequency of recanalization, the time from the onset of AMI to SICT, the dose of urokinase, or other clinical parameters among patients at the three stages. Only the hearts of patients in stage LI showed hemorrhagic infarction, and it was found in 15 of 18 of these hearts. Marked diffuse hemorrhage was noted in six hearts, all of which showed recanalization after SICT. However, even in three patients in stage II without recanalization after SICT, moderate diffuse bleeding was evident. In all hearts, the hemorrhagic area was mostly localized within the infarct area. Thus, in most of the patients with AMI treated with SICT, hemorrhage increases gradually after SICT, becomes moderately or markedly diffuse after 4 hr, and is replaced by fibrosis after 3 to 4 weeks. The hemorrhagic infarction is due to the combined effects of reperfusion and large doses of urokinase. The time delay of bleeding seems to depend on the low perfusion pressure in the portion distal to the stenosed, infarct-related coronary artery. It is unlikely that hemorrhage expands the infarct area.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTSubaortic stenosis is well known to complicate the clinical course of patients with single ventricle or univentricular hearts, and we have previously suggested that the development of subaortic stenosis in such patients may be causal to and/or accelerated by previous banding of the main pulmonary trunk. To further define the relationship between banding of the pulmonary artery in patients with univentricular hearts and the development of subaortic stenosis, we examined the morphologic substrate and timing of the development of subaortic stenosis in 43 patients seen at our institution from January 1, 1970, through June 30, 1985. These 43 patients include all patients in this period with an unequivocal univentricular heart whose longitudinal data was available for follow-up. We excluded patients who died within 1 week of surgery, patients lost to follow-up, and patients with evidence of subaortic stenosis before banding. Thirty-one of 43 patients (72. 1%) developed subaortic stenosis subsequent to banding of the main pulmonary artery. The mean age at banding of those patients who developed subaortic stenosis was 0.21 years, and subaortic stenosis was recognized at a mean age of 2.52 years. For the specific cohort of patients whose ventricular morphology was a main chamber of left ventricular type supporting the pulmonary artery and a rudimentary right ventricle supporting the transposed aorta (32 patients), 27 developed subaortic stenosis (84.4%). Subaortic stenosis in the classic form of single ventricle usually results from progressive restriction of a wholly muscular interventricular communication. Banding of the pulmonary artery by producing myocardial hypertrophy undoubtedly accelerates the potential for subaortic stenosis in these patients. Furthermore, one must realize that subaortic stenosis may be present in the absence of a resting pressure gradient, and such subaortic stenosis can usually be unmasked by stimulation with isoprenaline. Finally, one must be guarded in advocating banding of the pulmonary artery in patients with single ventricle, realizing that subaortic stenosis strongly influences the outcome of more definitive surgery in these patients.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID