摘要:

SUMMARYThe absorption and disposition of quinidine were measured in nine patients following single oral and intravenous dosing. A new specific chromatographic method was used to measure the drug in plasma and urine. After intravenous administration, the plasma half-life (t1/2β) was 7.8 ± 0.7 h, the volume of distribution (Vd) was 3.0 ± 0.5 liters/kg, and the total body clearance was 4.8 ± 0.8 ml/min/kg. After oral administration, 87 ± 7% (mean ± SEM) was available to the systemic circulation. Quinidine was removed primarily by hepatic metabolism, with the renal clearance averaging only 1.0 ± 0.2 ml/min/kg. Mean quinidine concentrations were estimated in 42 patients on chronic therapy by averaging blood levels during a dosing interval. In patients without heart failure, these corresponded well to mean drug levels predicted from the pharmacokinetic parameters measured after a single intravenous dose, but in patients with heart failure, the values for mean quinidine concentrations were higher than predicted. This suggests that impaired elimination of the drug or a decreased volume of its distribution, or both, may develop in heart failure.

ISSN:0009-7322    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SUMMARYProlonged (< 152 msec) calculated sinoatrial conduction times (SACT) were found in 24 of 470 patients studied by the atrial extrastimulus technique, ranging from 155 to 220 msec (180 ± 4.4; mean ± SEM). There were 18 males and six females with ages of 29 to 85 (mean 65 ± 2.6). Electrocardiographic monitoring revealed significant sinus or atrial dysrhythmias in 19 (79%) patients. Of these 19, 15 had persistent sinus bradycardia and/or sinoatrial block, three had sinus bradyarrhythmia with paroxysmal atrial tachycardia, and one had isolated atrial tachycardia. Additional electrophysiological evidence of sinus node or atrial dys function was present in 11 patients. Four patients needed permanent pacing during follow-up (mean follow-up period of 427 ± 39 days) because of symptomatic bradyarrhythmia. Three patients died, none suddenly.In conclusion, prolonged calculated SACT was associated with a high incidence of electrocardiographic and electrophysiologic abnormalities of sinus node and/or atrium. Despite this, bradyarrhythmic morbidity was relatively low, suggesting that prolonged sinoatrial conduction time in the absence of symptoms is not an indication for prophylactic pacing.

ISSN:0009-7322    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SUMMARYThirty-three patients with Wolff-Parkinson-White syndrome were studied electrophysiologically before and after administration of intravenous procainamide and oral quinidine sulfate. Procainamide prolonged the shortest R-R (SRR) interval between two consecutive pre-excited beats during atrial fibrillation 20–70 msec in 15 of 21 patients with no change observed in 6 of 21 patients.Quinidine sulfateprolonged the SRR 20–170 msec in all 16. In 14 of 18 patients where procainamide and quinidine were comparable, quinidine prolonged the SRR 30–100 msec more than procainamide. Procainamide and quinidine both tended to prolong the effective refractory period of atrial, ventricular, and accessory pathway tissue as well as to slow antegrade and retrograde conduction in the accessory pathway. However, exceptions were noted. The assessment of pharmacological effects was frequently limited using determinations of refractory periods alone. Because of the variabilit observed in drug response, patients with Wolff-Parkinson- White syndrome and a history of atrial fibrillation with a rapid ventricula response should have atrial fibrillation electively induced while on therapy with procainamide or quinidine.

ISSN:0009-7322    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SUMMARYWe evaluated the usefulness of the surface electrocardiogram to predict the presence of postoperative trifascicular damage. We used the pre and postoperative electrocardiograms and postoperative His bundle electrograms from 50 patients an average of 3.8 years following tetralogy of Fallot (TF) and ventricular septal defect (VSD) repair. Right bundle branch block (RBBB) and RBBB with left anterior hemiblock (LAH) developed in 88% and 18%, respectively, and 22% had transient postoperative complete heart block (CHB). Mean P-A and A-H conduction times were 16.6 and 84.9 msec and were not different from 37 age-matched normal patients and 61 patients with unoperated TF and VSD. The mean H-V conduction time of 48.5 msec was significantly increased compared to the other two groups. Ten postoperative patients had H-V times of 55 msec or greater, indicating trifascicular damage. Of these, five had electrocardiographic bifascicular block (RBBB with LAH) with or without additional 10 A-V block. The remaining five patients' electrocardiograms did not suggest trifascicular damage. Since postsurgical trifascicular damage may progress to late onset CHB, conduction studies are indicated to identify patients at risk, despite surface electrocardiographic findings.

ISSN:0009-7322    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SUMMARYTemporary inhibition of permanently implanted demand pacemakers has been previously described. Demand pacemakers may be inhibited by waving a magnet over the region of the pacemaker generator or by chest wall stimulation. The former may not inhibit most of the bipolar pacemakers, whereas the latter may be time consuming and may cause patient discomfort.Another method is described which utilized a commercially available Cordis Omnicor Programmer, Model 166-B, to temporarily inhibit bipolar and unipolar pacemakers. By placing the programmer over the skin where the pacemaker generator is implanted and/or over the area of the subcutaneous pervenous lead and activating the programmer multiple times at a rate faster then the pacing rate, the demand pacemakers are inhibited. After testing the efficacy in vitro, the method was successfully tried on 45 patients. Fifteen of these patients had unipolar pacemakers. Pacemakers marketed by Medtronic, Cordis, Starr-Edwards, C.P.I., and Arco were tested.Temporary inhibition of permanent demand pacemakers is desirable under various clinical situations. The method herein described has the advantages of being simple, quick, painless, and is effective for both unipolar and bipolar pacemakers.

ISSN:0009-7322    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SUMMARYA quantification of the Frank and McFee-Parungao orthogonal electrocardiogram of 175 normal children, ages 2–10 years is presented. There are significant differences in age groups 2–5 and 6–10. The QRS voltages of the younger group demonstrate 1) greater Z anterior, 2) greater initial X right, 3) greater terminal X right, 4) smaller Y inferior, and 5) the T vector is oriented more posteriorly.There are significant differences between the two lead systems. 1) Frank spatial voltages are 70% of those of McFee. 2) Frank X left is 70% of McFee, but terminal X right is 75% and initial X right is 60% of McFee. 3) Frank Y inferior is 78% of McFee, but initial Y superior is 83% and terminal Y superior 61% of McFee. 4) Frank Z anterior is 64% and Frank Z posterior is 70% of McFee. 5) In terms of ratios the Frank is relatively less inferior, about equally posterior and more terminally right. 6) The T vector is more posterior in Frank than McFee.

ISSN:0009-7322    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SUMMARYElectrocardiograms and cardiac electrograms now frequently are measured for both clinical and experimental purposes by direct digital sampling, with no recording of the signal in analog form. This study examined the question of what sampling rates were required to measure accurately the continuous waveforms from the digital samples. Body surface waveforms and intracellular and extracellular waveforms measured directly from cardiac tissues were evaluated. Cardiac measurements included waveforms from the atrium, ventricle, atrioventricular transmission system and individual Purkinje strands. Sampling rates as high as 15,000 samples/sec were required to record accurately extracellular waveforms of the ventricular conduction system. Decreasing sampling rates were required as the recording site shifted through the ventricle to the body surface, where sampling rates as high as 1500 samples/sec were necessary.

ISSN:0009-7322    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SUMMARYRight bundle branch block (RBBB) was produced in five dogs by incising the main right bundle branch. Body surface isopotential maps of each of these dogs were obtained from 85 thoracic electrocardiograms using a mini-computer technique. In addition, the epicardial activation process was obtained from the same dog, and were correlated with the map pattern.Following the incision, the following characteristic changes in the map pattern occurred: The ventricular activation was prolonged in RBBB as compared with normal. During the early stage of ventric ular excitation, the maximum was shifted leftward due to the activation wavefronts in the left ventricle in contrast to the double septal activation in the control. A localized lower potential area (a concavity) which appears in the middle stage of activation within the anterior positivity as an initial representation of breakthrough was also shifted left-and-downward and delayed in appearance. The sudden change in the potential distribution subsequently observed occurred quite differently. The terminal excitation was characterized by the maximum occurring over the right chest in RBBB in contrast to the left chest in control. These changes in the pattern of the potential distribution were compatible with the changes in the ventricular excitation process.This result may be applied to human RBBB map interpretation.

ISSN:0009-7322    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SUMMARYThe ECG changes during exercise are described in 71 patients with a previous anteroseptal or anterolateral infarction (ANT-MI) and in 73 patients with an old posterior or inferior wall infarction (INF-MI). Left ventricular angiograms in 95 patients yielded a good correlation between areas of dyssynergy and the QRS pattern at rest. The ST changes in patients with coronary artery disease and a normal ECG at rest, and in normal subjects, were oriented toward the right, posteriorly and superiorly. In patients with INF-MI anteroand inferior wall dyssynergy, the ST changes were more inferiorly oriented. Anteriorly-oriented ST changes were associated with anterior wall or apical dyssynergy and with ANT-MI. Thus the spatial direction of the ST changes during exercise is related to three independent factors: those factors which cause the ST changes in normal subjects, the degree of myocardial ischemia in that particular case, and the extent of dyssynergic areas in the wall of the left ventricle.

ISSN:0009-7322    

出版商:OVID    

年代:1977

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1977

数据来源: OVID