ISSN:0009-7322    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

Infarct size has been estimated from serial serum creatine phosphokinase (CPK) changes, but the contribution of noncardiac CPK may interfere. Results would also be influenced if CPK disappearance varied with hemodynamic changes. Since MB CPK is a marker more specific to myocardium, infarct size was estimated from serum MB changes in 16 patients. In addition, 21 chronically instrumented conscious dogs subjected to tachycardia, decreased cardiac output or hepatic or renal ischemia were studied to evaluate the dependence of CPK disappearance on hemodynamics. MB CPK in human tissue extracts and serum was quantified with a new, rapid, glass bead-batch adsorption technique, verified with CPK isoenzymes prepared from human myocardium. Among tissues surveyed, only myocardium contained appreciable MB CPK. Infarct size estimated from MB correlated with total serum CPK in patients with uncomplicated myocardial infarction (r= 0.97, N = 12). In patients with infarction given intramuscular injections, total CPK curves were distorted but MB CPK curves were not apparently affected. Hemodynamic alterations in conscious dogs did not markedly affect the disappearance rate (kd) of intravenously injected, radioactively labeled, canine myocardial CPK, although kdwas shown to depend on reticuloendothelial system activity. These findings suggest that estimation of the extent of infarction based on serum MB CPK should be useful despite hemodynamic deterioration associated with infarction or interference of noncardiac CPK.

ISSN:0009-7322    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

In order to evaluate the events preceding primary ventricular fibrillation (PVF), continuous tape recording was performed in 262 patients consecutively admitted to the hospital within six hours of infarction in whom antiarrhythmic therapy was withheld. Warning arrhythmias (defined as ventricular ectopic beats occurring with a frequency of more than five beats per minute, in runs, falling in the vulnerable phase of the cardiac cycle or being multiformed) were registered in an equal percentage in patients who did or did not develop PVF. Immediately prior to PVF seven patients showed sinus tachycardia, 10 a sinus rate ranging from 60 to 100 beats per minute and two bradycardia due to complete atrioventricular block. The ventricular ectopic beat initiating PVF had a late coupling interval (QR′/QT ≥ 0.85) in 11 patients and a left bundle branch block configuration as frequent as a right bundle branch block.Conclusions: 1) Warning arrhythmias are not considered good criteria for institution of antiarrhythmic therapy in order to prevent PVF. 2) In patients with sinus rhythm there may be an association between heart rate and onset of PVF. 3) The malignancy of a ventricular ectopic beat is not determined by its coupling interval or its configuration.

ISSN:0009-7322    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

In order to determine the electrophysiological changes that occur during coronary occlusion and following reperfusion, 19 mongrel dogs were studied. Refractory periods were determined by the extrastimulus method in nonischemic and ischemic zones prior to and after variable periods of left anterior descending artery occlusion and reperfusion. After 15-30 minutes of occlusion, refractory periods in the nonischemic zones remained unchanged while in the ischemic zone theyshortenedby 17%, resulting in a dispersion of refractoriness. Within three minutes of reperfusion, arrhythmias appeared together with a marked directional change of refractory periods to aprolongationby 34% (P< 0.001) in the ischemic zone and by 3% (P< 0.02) in the nonischemic zone. Refractory periods returned to baseline values after 60 minutes of reperfusion. After 60-90 minutes of occlusion, refractory periods in the nonischemic zones were unchanged whereas in the ischemic zone they demonstrated adecreaseby 28% (P< 0.001), again resulting in a dispersion of refractoriness. Within five minutes of reperfusion, refractory periods in the ischemic zoneprolongedby 44% (P< 0.001). Similar but smaller directional changes were also seen in nonischemic zones. Concomitant with the observed prolongation in refractory periods frequent ventricular ectopic activity was again documented. In addition, refractory periods did not return to control values after periods of observation up to 120 minutes in this group. In seven dogs, complete heart block was induced to ascertain the rate of idioventricular pacemaker and the effect of ventricular overdrive on the escape interval. Control ventricular rates (53.3 ± 5.7 beats/min) remained unchanged (52.3 ± 5.6) following coronary occlusion, but decreased to 48.0 ± 4.4 (P< 0.05) during reperfusion. Mean control escape intervals (1.8 ± 0.2 sec) did not change after occlusion (1.7 ± 0.2 sec) but prolonged to 2.1 ± 0.2 sec (P< 0.05) following reperfusion. In conclusion: 1) sudden prolongation in refractory periods following reperfusion leads to an overshoot resulting in a dispersion of refractoriness temporally related to the onset of ventricular arrhythmias and 2) re-entry, and not enhanced automaticity, appears to be the mechanism for postperfusion arrhythmias.

ISSN:0009-7322    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

Patterns of antegrade and retrograde conduction and refractory periods were studied using His bundle electrogram recordings, incremental atrial and ventricular pacing and the extrastimulus technique. In 36/50 patients antegrade conduction was "better" than retrograde conduction (group I), as evidenced by a) onset of retrograde atrioventricular (A-V) nodal Wenckebach phenomenon at a slower rate compared to the antegrade counterpart (25 patients: group IA) or b) no ventriculo-atrial conduction at all ventricular paced rates (11 pts: group IB). The site of retrograde block in group IB patients was the A-V node. In eight patients (group II), antegrade and retrograde conduction appeared to be equal up to maximum paced rates of 160 beats/min. In six patients (group III) retrograde conduction was "better" than antegrade conduction, as indicated by onset of antegrade A-V nodal Wenckebach periods at slower rates than retrograde Wenckebach periods. During antegrade refractory period studies the area of maximum refractoriness was the A-V node in 19/40 patients, the His-Purkinje system (HPS) 6/40, and the atrial muscle in 15/40. During retrograde refractory period studies the A-V node was the area of maximum refractoriness in 12/36 pts (4/40 patients had A-V dissociation during ventricular pacing), the HPS in 12/36, and the ventricular muscle in 10/36. In 2/36 patients the site of maximum refractoriness retrogradely could not be determined: The area of maximum refractoriness during both antegrade and retrograde refractory period studies was the same in 11 patients (A-V node in seven and HPS in four), was different (i.e., A-V node or HPS) in 18 patients, and was the atrial or ventricular muscle in six patients. In five patients, including four patients in whom V-A conduction failed to occur, the above comparisons were not made.It is concluded that 1) antegrade conduction is better than retrograde conduction in most patients; 2) it is not always possible to predict area of maximum refractoriness during premature stimulation (both atrium and ventricle) from observations made during incremental pacing; 3) it is equally difficult to extrapolate patterns of retrograde conduction and refractory periods from results of antegrade conduction and refractory period studies.

ISSN:0009-7322    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

Atrioventricular (A-V) conduction, ventriculo-atrial conduction and mechanism of tachycardia were studied by programmed electrical stimulation before and after the administration of ouabain in 15 patients suffering from paroxysmal supraventricular re-entrant tachycardia. In 13 patients the tachycardia circuit was confined to the A-V node. In two patients the stimulation study showed that an accessory pathway was used in a ventriculo-atrial direction during tachycardia. Ouabain lengthened the effective and functional refractory period of the A-V node and A-V nodal transmission time in all patients in whom this could be studied. Only six patients showed lengthening in ventriculo-atrial conduction time or refractory period of the ventriculo-atrial conduction system. In seven patients no tachycardia could be initiated after ouabain. The width of the zone of atrial premature beats able to initiate tachycardia (the tachycardia zone) narrowed in five patients, showed no change in two patients, and increased in one patient. In these eight patients the tachycardia zone shifted to longer premature beat intervals. Ouabain resulted in slowing of cardiac rate during tachycardia. Both patients who used an accessory pathway during tachycardia showed no change in width of their tachycardia zone following ouabain administration. Seven patients were restudied two weeks after chronic oral administration of digoxin. The results were similar to those obtained following ouabain administration. This indicates that in patients suffering from paroxysmal A-V nodal tachycardia the effect of chronic oral digoxin administration can be predicted from the study of the effect of ouabain during programmed stimulation of the heart.

ISSN:0009-7322    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

In patients with atrioventricular (A-V) nodal re-entrant paroxysmal supraventricular tachycardia (PSVT), atrial extrastimulus technique frequently reveals discontinuous A1-A2, H1-H2curves suggestive of dual A-V nodal pathways. To further test the hypothesis that these curves in fact reflect dual A-V nodal pathways, a ventricular extrastimulus (Vs) was coupled either to A2at a fixed A1-A2interval which reliably produced an A-V nodal re-entrant atrial echo (E) with a constant A2-E interval in two patients, or to QRS complex (V) during sustained PSVT with a constant E-E interval in one patient. Three response zones were defined: at longer A2-Vsor V-Vscoupling intervals, Vsmanifested no effect on the timing of E (Zone 1). At closer A2-Vsor V-Vscoupling interval, Vsconducted to the atrium, shortening the apparent A2-E or E-E interval (Zone 2). At shortest A2-Vsor V-Vscoupling interval, Vswas blocked retrogradely, and no E was induced (Zone 3).The ability of Vsto preempt control of the atria (Zone 2 response) strongly suggests the presence of dual A-V nodal pathways in these PSVT patients. If only a single pathway were present, Vswould of necessity collide with the antegrade impulse and could not reach the atria. The Zone 3 response occurs because of retrograde refractoriness of the fast pathway. Failure of the echo during Zone 3 probably reflects concealed conduction to the fast pathway, or possibly interference in the slow pathway.

ISSN:0009-7322    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

Precordial ST-segment mapping was applied serially in the coronary care unit for the study of 46 patients with myocardial infarction (MI), using a 49-lead system. Data from the maps were compared with clinical status of patients, conventional ECGs obtained simultaneously, and serum enzyme levels. Stability of the maps over a one hour period was noted in the early phase of admission. However, a drop of 32% of the sum of ST-segment elevations (+ ∑ ST) was detected in eight patients with uncomplicated anterior MI over the first 24 hours after admission. Extension of infarction was associated with abrupt rise of + ∑ ST, and was diagnosed in two cases from maps in the presence of unchanged standard ECGs. The course of ST elevations was followed more accurately by the map than the standard ECG in eight patients. Pericarditis invalidated the technique completely, due to persistent + ∑ ST. The standard ECG was superior to the map in following patients with inferior MI. A case of true posterior MI was more accurately delineated by maps of the posterior thorax than by the standard ECG. Intraventricular conduction defects and pacemaking interfered with the maps. Early repolarization produced stable maps; however, mapping showed no advantages over the standard ECG. Preinfarction angina can probably be followed by serial mapping of ST-segment depression.

ISSN:0009-7322    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

To evaluate the influence of the native coronary circulation on the reversibility of asynergy, ventriculograms before and after sublingual nitroglycerin were performed in 51 patients with coronary artery disease and asynergy. The severity of stenotic lesions and caliber of the distal coronary vessels were determined by comparison with external catheter tip diameter corrected for magnification. Of 42 asynergic zones associated with ≧ 90% proximal coronary occlusion, 27 (64%) were akinetic or dyskinetic while only 11 of 38 zones (29%) with < 90% occlusion showed akinesis (P< 0.005). Twenty-six of the 38 asynergic zones (69%) with < 90% occlusion were reversible in contrast to 19 of the 42 zones (45%) with ≧ 90% occlusion (P< 0.05). Coronary collaterals were observed in 23 of 42 (55%) zones with ≧ 90% occlusion in contrast to only 11 of 38 zones (29%) with < 90% occlusion (P< 0.05). Of the zones with both ≧ 90% occlusion and collaterals, 74% were reversible, in contrast to only 11% without collaterals (P< 0.001). Of the asynergic zones without collaterals, 63% with < 90% occlusion were reversible in contrast to only 11% with ≧ 90% occlusion (P< 0.001). Pathologic Q waves were associated with 24 of 42 zones (57%) with ≧ 90% occlusion compared to only nine of the 38 zones (24%) with < 90% occlusion (P< 0.01). The presence of Q waves was associated with a significant decrease in the incidence of reversibility regardless of the degree of coronary occlusion. Excluding the asynergic zones with either collaterals or Q waves, 79% with < 90% occlusion were reversible in contrast to only 37% with ≧ 90% coronary occlusion (P< 0.05). In contrast, the caliber of the distal vessel could not be correlated with either the severity of asynergy or the presence of collaterals and was similar in both reversible and irreversible asynergic zones.In summary, ≧ 90% proximal stenosis is associated with severe asynergy which is less likely to be reversible compared to asynergy associated with < 90% coronary occlusion. In the presence of ≧ 90% occlusion, coronary collaterals are associated with a significantly higher incidence of reversible asynergy and thus appear to serve a protective function. However, the caliber of the distal vesselper sedoes not effect the severity or reversibility of asynergy.

ISSN:0009-7322    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

A method for the echocardiographic detection of supravalvular aortic stenosis (SVAS) is described and the findings in a series of patients are presented. When compared to angiography, the echo tended to underestimate the severity of the supravalvular aortic obstruction. However, echocardiography appears to be a valuable, noninvasive method for detecting SVAS.

ISSN:0009-7322    

出版商:OVID    

年代:1975

数据来源: OVID