An Experimental Study on the Origin of T-Waves Based on Determinations of Effective Refractory Period from Epicardial and Endocardial Aspects of the Ventricle

Reynolds, Ernest W.; Ark, Condon R. Vander

doi:10.1161/01.res.7.6.943

Cited by 29 publications

(7 citation statements)

References 13 publications

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“…In this study, we recorded MAPs from multiple endocardial and epicardial sites in the human ventricle in situ by means of the contact electrode technique.7 8 The contact electrode has a tip diameter of 1 14 In our study, the longest average APD was measured in the septal and diaphragmatic area and the shortest at anteroapical and posterolateral sites. There are no endocardial data from a large mammalian species with which to compare this gradient.…”

Section: Discussionmentioning

confidence: 77%

Monophasic action potential mapping in human subjects with normal electrocardiograms: direct evidence for the genesis of the T wave.

Franz¹,

Bargheer²,

Rafflenbeul³

et al. 1987

Circulation

316

170

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T wave concordance in the normal human electrocardiogram (ECG) generally is explained by assuming opposite directions of ventricular depolarization and repolarization; however, direct experimental evidence for this hypothesis is lacking. We used a contact electrode catheter to record monophasic action potentials (MAPs) from 54 left ventricular endocardial sites during cardiac catheterization (seven patients) and a new contact electrode probe to record MAPs from 23 epicardial sites during cardiac surgery (three patients). All patients had normal left ventricular funtion and ECGs with concordant T waves. MAP recordings during constant sinus rhythm or right atrial pacing were analyzed for (1) activation time (AT) = earliest QRS deflection to MAP upstroke, (2) action potential duration (APD) = MAP upstroke to 90% repolarization, and (3) repolarization time (RT) = AT plus APD. AT and APD varied by 32 and 64 msec, respectively, over the left ventricular endocardium and by 55 and 73 msec, respectively, over the left ventricular epicardium. On a regional basis, the diaphragmatic and apicoseptal endocardium had the shortest AT and the longest APD, and the anteroapical and posterolateral endocardium had the longest AT and the shortest APD (p < .05 to < .0001). RT was less heterogeneous than APD, and no significant transventricular gradients of RT were found. In percent of the simultaneously recorded QT interval,-epicardial RT ranged from 70.8 to 87.4 (mean 80.7 + 3.9) and endocardial RT ranged from 80 to 97.8 (mean 87.1 4.4) (p < .001). Plotting of APD as a function of AT, independent of the recording site, revealed a close inverse relationship, such that progressively later activation was associated with progressively earlier repolarization The linear regression slope of this relationship averaged from all 10 hearts was -1.32 + 0.45 (r = -.78 + . 10). These data suggest a transmural gradient of repolarization,with earlier repolarization occurring at the epicardium. The negative correlation between AT and APD, which was found at both the endocardial and epicardial surface and had an average slope of greater than unity, may further contribute to a positive ventricular gradient and T wave concordance.

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Section: Discussionmentioning

confidence: 77%

Monophasic action potential mapping in human subjects with normal electrocardiograms: direct evidence for the genesis of the T wave.

Franz¹,

Bargheer²,

Rafflenbeul³

et al. 1987

Circulation

316

170

View full text Add to dashboard Cite

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“…It has been shown by several authors that repolarization is accelerated in myocardial fibers exposed to anoxia (25, 26) or after coronary occlusion (20). The second interpretation therefore seems preferable, although, in the present state of our knowledge, the two other hypotheses cannot be completely ruled out.…”

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confidence: 79%

Body Surface Distribution of Equipotential Lines during Atrial Depolarization and Ventricular Repolarization

Taccardi

1966

Circulation Research

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In 15 normal male human subjects and 6 dogs, 200 chest electrocardiograms were sequentially recorded. The distribution of equipotential lines on the thoracic surface was determined at 20 to 30 instants of time during atrial activation and ventricular recovery. In humans, the potential pattern is constantly dipolar, with one maximum and one minimum, during the P wave. The motion of the potential maximum and minimum on the chest surface appears to be related to the progress of the excitation through the auricular walls. At the end of the QRS interval, the simultaneous presence of activation and recovery potentials is generally observed, giving rise to several simultaneous maxima and minima. During the ST and T interval, recovery potentials show a dipolar distribution in normal subjects, but tripolar patterns are observed when the recovery process is altered in a circumscribed myocardial region. In dogs, multipolar distributions are frequently observed during the P wave, the ST segment and the T wave. During atrial activation and ventricular recovery, chest maps yield more information on the electrical activity of the heart (both normal and abnormal) than is offered by ordinary limb and precordial leads.

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“…Since the subendocardial temperature was essentially constant during this short period, it is reasonable to assume that if the 2 determinations could have been made simultaneously, the subendocardial effective refractory period would not have changed. When the data in this experiment were adjusted for the time required for excitation to spread from endocardium to epicardium, 1 it was found that when the T waves in the epieardial lead were negative, recovery at the epicardium was completed 2 msec, (not a significant difference) after that of the endocardium, but when the T waves were positive, it was completed 35 msec, before recovery of the endocardium. In 1 other animal in which a similar study was done, the T waves which were initially negative became positive when the epicardium became 7.2 C. warmer than the endocardium, as is shown in figure 5.…”

Section: Transmural Temperature Measurementsmentioning

confidence: 91%

“…N A previous publication, 1 it was shown that measurements of the effective refractory period were useful in following the time course of electrical recovery. Although this studj' was largely concerned with the local order of transmural recovery associated with negative T waves, a few observations during the acute phase of experimental infarction confirmed the fact that recovery was accelerated, especially in the deeper myocardial layers.…”

mentioning

confidence: 99%

“…Methods The equipment used and manner of measuring the effective refractory period were similar to those used in a previous study, 1 with the addition of a special circuit permitting the application of a single test stimulus at a time when the oscillograph had reached optimal paper speed. A suprathreshold stimulus was used for these measurements, but since there was a tendency for threshold to rise some hours after the ligation, it was considered essential to start with a stronger stimulus than had been employed in earlier studies.…”

mentioning

confidence: 99%

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Effect of Acute Myocardial Infarction on Electrical Recovery and Transmural Temperature Gradient in Left Ventricular Wall of Dogs

Reynolds

Ark

Johnston

1960

Circulation Research

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Accelerated recovery, as manifested by shortening of the effective refractory period after coronary artery ligation, occurred at either the epicardial or endocardial surface or both in 11 of 13 animals tested with a mean shortening of 15.7 per cent at the epicardial and 13 per cent at the endocardial levels. These changes are attributed to severe anoxia and are believed to be limited to the ischemic area, since studies in the periphery of an infarcted zone show no significant changes in the first 3 hours. In one instance a minor acceleration of recovery was found after 3 hours at the endocardium. All studies showed a final period of delayed recovery. It is felt that this probably reflects a prolonged duration of the membrane action potential during the later stages of myocardial infarction. This is supported by both experimental and human electrocardiographic data which show prolongation of the Q-T interval in association with deeply inverted T waves following the period of acute injury. Transmural temperature studies after coronary artery ligation showed a prompt fall in 2 studies out of 7 and no acute change in the others. Irrigating the pericardial sac with warm Ringer's solution reversed the pre-existing transmural temperature gradient, caused the T waves in epicardial leads to change from negative to positive, and reduced the duration of the effective refractory period at both the endocardial and epicardial surfaces, especially the latter. During the time that the T waves were upright, recovery was completed earlier at the epicardial than at the endocardial surface.

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An Experimental Study on the Origin of T-Waves Based on Determinations of Effective Refractory Period from Epicardial and Endocardial Aspects of the Ventricle

Cited by 29 publications

References 13 publications

Monophasic action potential mapping in human subjects with normal electrocardiograms: direct evidence for the genesis of the T wave.

Monophasic action potential mapping in human subjects with normal electrocardiograms: direct evidence for the genesis of the T wave.

Body Surface Distribution of Equipotential Lines during Atrial Depolarization and Ventricular Repolarization

Effect of Acute Myocardial Infarction on Electrical Recovery and Transmural Temperature Gradient in Left Ventricular Wall of Dogs

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