Arrhythmogenic effects by local left ventricular stretch

The cardiotonic and arrhythmogenic effects, and the excitatory effect on respiration of "Kyushin," a drug containing toad venom, were studied in comparison with those of digoxin. In anesthetized rabbits, the maximum rate of rise of left ventricular systolic pressure (max dP/dt) was measured as an index of cardiotonic effect, and the respiratory flow was measured as an index of respiratory function. Intraduodenal (i.d.) administration of 80 mg/kg "Kyushin" produced a cardiotonic effect and an excitatory effect on respiration, but i.d. administration of 16 mg/kg digoxin produced only a cardiotonic effect, and conversely inhibited respiration. In anesthetized open-chest guinea pigs, myocardial contractile force was measured as an index of cardiotonic effect and the arrhythmogenic effect was evaluated from the appearance of arrhythmic myocardial contraction. By i.d. administration of a 20% ethanol suspension or solution, "Kyushin" and digoxin showed a cardiotonic activity with doses higher than 40 mg/kg and 0.25 mg/kg, respectively. The arrhythmogenic doses of "Kyushin" and digoxin by i.d. administration were 2560 mg/kg and 2 mg/kg, respectively, suggesting that the safety margin of "Kyushin" is broader than that of digoxin.

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Actions of Phenylephrine, Isoproterenol, and Epinephrine Halothane on Endocardial Conduction and Activation in Canine Left Ventricular Papillary Muscles

Anesthesiology ◽

10.1097/00000542-199707000-00016 ◽

1997 ◽

Vol 87 (1) ◽

pp. 117-126 ◽

Cited By ~ 3

Author(s):

Sanja Vodanovic ◽

Lawrence A. Turner ◽

Raymond G. Hoffmann ◽

John P. Kampine ◽

Zeljko J. Bosnjak

Keyword(s):

Conduction Velocity ◽

Left Ventricular ◽

Conduction Time ◽

Papillary Muscles ◽

Bipolar Electrodes ◽

Beta Agonists ◽

Purkinje System ◽

Slow Conduction ◽

Arrhythmogenic Effects ◽

Stimulation Of

Background Myocardial sensitization by halothane to the arrhythmogenic effects of epinephrine involves synergistic actions mediated by alpha 1- and beta-adrenoceptors. Halothane potentiates a transient a1-adrenoceptor-mediated negative dromotropic effect of epinephrine on Purkinje fibers. This study examines how halothane alters the actions of alpha 1- and beta-agonists and epinephrine on endocardial conduction. Methods Superfused canine papillary muscles were mapped to locate a Purkinje-ventricular muscle junction (PVJ), and bipolar electrodes were placed to measure Purkinje and endocardial conduction velocity and PVJ conduction time during stimulation of the Purkinje layer. The effects of exposure to 5 microM phenylephrine, 1 microM isoproterenol, or 5 microM epinephrine on conduction were determined in the absence and presence of 0.4 mM halothane in three groups of 10 preparations. Results Isoproterenol slightly increased Purkinje conduction velocity and markedly improved conduction at the PVJ and in the endocardium similarly in the presence or absence of halothane. Phenylephrine depressed Purkinje velocity (-12%) only in the presence of halothane and did not slow conduction at the PVJ or in the myocardium. Epinephrine transiently depressed Purkinje velocity, more so with (-22%) than without (-12%) halothane (P < or = 0.01), and simultaneously facilitated conduction at the PVJ and in the myocardium. Conclusions The prodysrhythmic actions of epinephrine with halothane may involve disparate effects on conduction, including speeding on conduction at the PVJ and in the myocardium, similar to that produced by isoproterenol, accompanied by simultaneous but transient alpha 1-mediated depression of conduction in the Purkinje system.

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Arrhythmogenic effects by local left ventricular stretch: effects of flecainide and streptomycin

Naunyn-Schmiedeberg s Archives of Pharmacology ◽

10.1007/s00210-014-0988-y ◽

2014 ◽

Vol 387 (8) ◽

pp. 763-775 ◽

Cited By ~ 6

Author(s):

Stefan Dhein ◽

Christine Englert ◽

Stephanie Riethdorf ◽

Martin Kostelka ◽

Pascal Maria Dohmen ◽

...

Keyword(s):

Left Ventricular ◽

Arrhythmogenic Effects

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Mitochondria in Cardiomyopathy: Alterations in Size, Number and Internal Structures

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100100378 ◽

1968 ◽

Vol 26 ◽

pp. 126-127

Author(s):

George Hug ◽

William K. Schubert

Keyword(s):

Heart Failure ◽

Biochemical Analysis ◽

Left Ventricular ◽

Size Number ◽

Internal Structures ◽

Left Ventricular Outflow ◽

Chest X Ray ◽

Myocardial Fibers ◽

Muscle Biopsies ◽

Needle Liver Biopsy

A white boy six months of age was hospitalized with respiratory distress and congestive heart failure. Control of the heart failure was achieved but marked cardiomegaly, moderate hepatomegaly, and minimal muscular weakness persisted.At birth a chest x-ray had been taken because of rapid breathing and jaundice and showed the heart to be of normal size. Clinical studies included: EKG which showed biventricular hypertrophy, needle liver biopsy which showed toxic hepatitis, and cardiac catheterization which showed no obstruction to left ventricular outflow. Liver and muscle biopsies revealed no biochemical or histological evidence of type II glycogexiosis (Pompe's disease). At thoracotomy, 14 milligrams of left ventricular muscle were removed. Total phosphorylase activity in the biopsy specimen was normal by biochemical analysis as was the degree of phosphorylase activation. By light microscopy, vacuoles and fine granules were seen in practically all myocardial fibers. The fibers were not hypertrophic. The endocardium was not thickened excluding endocardial fibroelastosis. Based on these findings, the diagnosis of idiopathic non-obstructive cardiomyopathy was made.

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Intracellular EDEMA does not adversely affect the ability to cryopreserve intact hearts

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100147235 ◽

1993 ◽

Vol 51 ◽

pp. 278-279

Author(s):

CL Hastings ◽

RD Carlton ◽

FG Lightfoot ◽

AF Tryka

Keyword(s):

Cell Injury ◽

Median Sternotomy ◽

Left Ventricular ◽

Ventricular Free Wall ◽

Hypoxic Cell ◽

Free Wall ◽

Sprague Dawley ◽

Left Ventricular Free Wall ◽

Sprague Dawley Rats

The earliest ultrastructural manifestation of hypoxic cell injury is the presence of intracellular edema. Does this intracellular edema affect the ability to cryopreserve intact myocardium? To answer this guestion, a model for anoxia induced intracellular edema (IE) was designed based on clinical intraoperative myocardial preservation protocol. The aortas of 250 gm male Sprague-Dawley rats were cannulated and a retrograde flush of Plegisol at 8°C was infused over 90 sec. The hearts were excised and placed in a 28°C bath of Lactated Ringers for 1 h. The left ventricular free wall was then sliced and the myocardium was slam frozen. Control rats (C) were anesthetized, the hearts approached by median sternotomy, and the left ventricular free wall frozen in situ immediately after slicing. The slam frozen samples were obtained utilizing the DDK PS1000, which was precooled to -185°C in liguid nitrogen. The tissue was in contact with the metal mirror for a dwell time of 20 sec, and stored in liguid nitrogen until freeze dry processing (Lightfoot, 1990).

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Ultrastructural observations of the aorta of calves implanted with a mechanical left ventricular assist device

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100161734 ◽

1990 ◽

Vol 48 (3) ◽

pp. 834-835

Author(s):

J P Cassella ◽

V Salih ◽

T R Graham

Keyword(s):

Left Ventricular Assist Device ◽

Ventricular Assist Device ◽

Left Ventricular ◽

Aortic Tissue ◽

Assist Device ◽

Ventricular Assist ◽

Transmission Electron ◽

Left Ventricular Assist ◽

Preliminary Study

Left ventricular assist systems are being developed for eventual long term or permanent implantation as an alternative to heart transplantation in patients unsuitable for or denied the transplant option. Evaluation of the effects of these devices upon normal physiology is required. A preliminary study was conducted to evaluate the morphology of aortic tissue from calves implanted with a pneumatic Left Ventricular Assist device-LVAD. Two 3 month old heifer calves (calf 1 and calf 2) were electively explanted after 128 days and 47 days respectively. Descending thoracic aortic tissue from both animals was removed immediately post mortem and placed into karnovsky’s fixative. The tissue was subsequently processed for transmission electron microscopy (TEM). Some aortic tissue was fixed in neutral buffered formalin and processed for routine light microscopy.

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Left Ventricular Hypertrophy

Guides Newsletter ◽

10.1001/amaguidesnewsletters.2014.marapr04 ◽

2014 ◽

Vol 19 (2) ◽

pp. 11-15

Author(s):

Steven L. Demeter

Keyword(s):

Risk Factors ◽

Left Ventricular Hypertrophy ◽

Ventricular Hypertrophy ◽

Left Ventricular Mass Index ◽

Medical Science ◽

Careful Analysis ◽

Left Ventricular ◽

Hypertensive Disease ◽

Accurate Analysis ◽

Clear Explanation

Abstract The fourth, fifth, and sixth editions of the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) use left ventricular hypertrophy (LVH) as a variable to determine impairment caused by hypertensive disease. The issue of LVH, as assessed echocardiographically, is a prime example of medical science being at odds with legal jurisprudence. Some legislatures have allowed any cause of LVH in a hypertensive individual to be an allowed manifestation of hypertensive changes. This situation has arisen because a physician can never say that no component of LVH was not caused by the hypertension, even in an individual with a cardiomyopathy or valvular disorder. This article recommends that evaluators consider three points: if the cause of the LVH is hypertension, is the examinee at maximum medical improvement; is the LVH caused by hypertension or another factor; and, if apportionment is allowed, then a careful analysis of the risk factors for other disorders associated with LVH is necessary. The left ventricular mass index should be present in the echocardiogram report and can guide the interpretation of the alleged LVH; if not present, it should be requested because it facilitates a more accurate analysis. Further, if the cause of the LVH is more likely independent of the hypertension, then careful reasoning and an explanation should be included in the impairment report. If hypertension is only a partial cause, a reasoned analysis and clear explanation of the apportionment are required.

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