The Effect of Levarterenol on Polarographic Myocardial Oxygen, the Epicardial Electrocardiogram and Contraction

E HAVE previously shown that the enicardial-surface electrocardiogram is an inadequate index of localized myocardial ischemia. While striking chanares of polarographic oxygen and contractility regularly occur a few seconds after coronary arterial branch occlusion, epieardial electrocardiographic changes are delayed and sometimes absent.1 Intramyocardial electrocardiographic studies, on the other hand, reveal that localized ischemia disturbs myocardial electrical activity at least as early as either oxygenation or contractility, and over a more extensive area.We have developed a technique for amplification and recording of oxygen-reduction currents and electrocardiograms simultaneously from the same lead-point 2 "4 in the myocardium. This technique was combined with motion-picture records of muscle contraction 5 and epicardial-surface color. Thus, simultaneous information about electrical activity, oxygenation, and contractility in locally altered myocardium and adjacent, undisturbed muscle became available. This makes possible, as we will show in the present paper, an assessment of the limitations of Supported by Eesearch Grant H-398 from the National Heart Institute, National Institutes of Health, V. S. Public Health Service.Dr. Katcher is a Postdoctoral Eesearch Fellow, National Heart Institute (HF-7812 C3).Eeeeived for publication July 11, 1961. epieardial heart-body leads, which are still indispensable links between open-chest situations and the body-surface electrical phenomena of concern to the clinician. We consider such an assessment to be elementary for understanding the behavior of the heart muscle and the electrocardiogram in coronary heart disease.6 Methods In 28 dogs, weighing 15 to 23 Kg., the heart was exposed under morphine-Dial-urethane-pentobarbital anesthesia.7 A branch of the left anterior descending coronary artery was isolated. Eight to 10 glass-insulated platinum electrodes were inserted in the left ventricle as previously described. 1The construction of electrodes had been modified from those used in our earliest work. 7 The relatively heavy shank was eliminated and the entire shaft was made of light glass fused to a 0.2-mm. platinum wire which was connected at a plasticinsulated junction to a very light lead wire (no. 42 copper enameled) insulated by polyethylene tubing ( fig. 1). A white glass bead, cemented to the shaft at the level desired, acted as a depth stop and as a marker for cinematographic studies of muscle contraction. These electrodes were made the cathodes of an electrolytic circuit measuring changes in oxygen polarographically according to the method of Davies and Brink 8 and Montgomery and Horwitz. 9 The electrodes were also used as exploring lead-points for direct heart-body electrocardiograms. The platinum tips in the myocardium have an electrolytic capacitance of approximately 0.5 microfarad, which makes it possible to use them for simultaneous measurement of extracellular electrical activity. The reference electrode for both systems consisted of approximately two f...

Section: Circulation Research Volume IX November 1961mentioning

confidence: 99%

Correlation of Intramyocardial Electrocardiograms with Polarographic Oxygen and Contractility in the Nonischemic and Regionally Ischemic Left Ventricle

Sayen

Peirce

Katcher

et al. 1961

“…While in man most of the disturbances are reported to be supraventricular in origin, 21 predominantly ventricular arrhythmias are seen in the dog. 22 " 24 In both species these abnormalities are usually associated with a rapid rise in blood pressure, and are closely related to dosage of catecholamine. 21 " 27 However, the ventricular tachycardia induced by norepinephrine does not lead to ventricular fibrillation, 24 and even in the presence of ventricular ectopic tachycardia, epinephrine does not precipitate fibrillation.…”

Section: Relation Of Early Arrhythmias To Drugs Usedmentioning

confidence: 99%

Electrocardiographic Patterns During Resuscitation After Experimentally Induced Ventricular Fibrillation

Miller

Nachlas

1964

Continuous closed-chest massage (mechanized and manual) and ventilation with pure oxygen were performed for 15 and 30-minute periods, to maintain viability in 43 dogs with electrically induced ventricular fibrillation. External countershocks were applied and 32 of the animals lived more than 48 hours. The return of electrical and hemodynamic functions of the heart, as well as the function of the central nervous system, were graded arbitrarily to characterize recovery from poor to excellent. Electrocardiographic changes (lead II) were studied in detail and compared with the gross result of survival or death, and also with more quantitative characterization of recovery. When the initial electrocardiogram after defibrillation contained a P wave, the prognosis was most favorable. When the P wave was absent the amount of ST segment depression in the initial complex differentiated the better from the poorer results. During the first hour following defibrillation, a variety of arrhythmias was noted, as well as varying degrees of change in the R, T, and ST portions of the electrocardiogram. The most serious arrhythmias, in decreasing severity, were idioventricular rhythm, atrio-ventricular block, and multiple premature ventricular contractions. Recovery was poorest when multiple arrhythmias occurred. Changes in the voltage of the R and T waves could not be correlated with prognosis. However, more favorable recoveries were noted in animals without significant changes in the ST segment than in animals having ST segment depression greater than 4 mm.

“…8 The behavior of dog no. 8 differed from the others in that a slow, shallow fall of oxygen at the center of the ischemic area was followed by a spontaneous rise almost to control values despite progressive electrocardiographic abnormality.…”

Section: The Depth Of Insertion For All Myocardial Electrode Sites Ismentioning

confidence: 99%

“…8 ' s Responses to 100 per cent oxygen inhalation, to 10 per cent oxygen (no. 4, 7, and 8), and to levarterenol (no.…”

Section: Re-explorationmentioning

confidence: 99%

“…The response to 100 per cent oxygen inhalation 3 ' 5 was studied in all animnls; the effect of hypoxia (10 per cent oxygen for 10 to 15 minutes), of levarterenol (0.1 to 0.5 /xg./Kg. ), 8 and of terminal intravenous potassium chloride (5 per cent) was studied in some. All hearts were serially sliced, and the microscopic findings were correlated with the gross necropsy data, using methods developed previously for studies in man.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Electrocardiogram, Myocardial Oxygen and Contraction in Scar and Collaterally Supplied Muscle After Experimental Coronary Ligation

Sayen

Sheldon

Peirce

et al. 1962

• The problem of understanding the behavior of the heart muscle and the electrocardiogram in coronary disease 1 has been approached experimentally in this laboratory by studies of acute regional ischemia under conditions permitting the use of sensitive and rapidly responding indices of change in local myocardial ox3 r genation, contraction, and electrical activity simultaneously in normal and abnormal muscle areas. "5 This paper is concerned with dogs which were permitted to survive acute coronary ligation and were studied again in a terminal open-chest experiment. Abstracts of some of the findings have been published. We set out to auswer the questions: How consistently and precisely can myocardial scars be demarcated by direct epieardial heart-body leads and by precordial leads? What correlation can be made between the extent of acute ischemic dysfunction in the distribution of a ligated coronary branch and the amount of myocardial scar ultimately found? In what ways does the behavior of collaterally supplied muscle differ from that of myocardium with a normal circulation ? MethodsIn 13 clogs (weights > 15 Kg.), the henvt was exposed through a midline incision under Supported by a research grant (H-398) from the National Heart Institute, National Institutes of Health, U. S. Public Health Service.Dr. Katcher is on a Special Research Fellowship HF-7812 (C-3).Received for publication July 10, 1962. 994morphine and dial-urethane-nembutal anesthesia, 2 and a smnll or medium-sized branch of the left anterior descending coronary artery was dissected free. An array of 8 to 10 light, glass-insulated platinum electrodes wns inserted.3 Bends attached to their shafts controlled depth of penetration and provided markers for cinematographic analysis of muscle contraction, as described previously. 3After allowing 30 to 45 minutes for stabilization, myocardial electrocardiograms (A.C. amplification) and polarographic oxygen records were obtained simultaneously from the exposed platinum tip of each electrode. 4 ' B One or more epieardial leads (A.C. amplifier) were followed, the exploring electrode being a cotton wick moistened with normal saline solution. In one animal, D.C. amplifier epicardial electrocardiogrnphic records were obtained by the "sweep" technique 4 from a silversilver chloride electrode. Responses to 100 per cent oxygen and . acute coronary branch occlusion or narrowing were studied. Exposure of the heart surface was sufficient for the ischemic areas to be completely surrounded by nonischemic myocardium. A coronary branch was then occluded permanently, usually by clamping followed by ligature. After periods of observation from onehalf to three hours (usually less than one hour), the chest was closed. The pericardium was left open. The animals were allowed to survive for 14 to 91 days. Body surface electrocardiograms were obtained in five dogs prior to the original ligation and in nine animals before re-exploration. These ordinarily consisted of transverse TOWS of anterior leads, from the midabdomen to the uppe...