Purkinje Fiber Dysplasia (Histiocytoid Cardiomyopathy) with Ventricular Noncompaction in a Savannah Kitten

2009 ◽  
Vol 46 (4) ◽  
pp. 693-697 ◽  
Author(s):  
H. B. Gelberg
Keyword(s):  
Organizational Development ◽  
Chromogranin A ◽  
Mitochondrial Disorder ◽  
Purkinje Fiber ◽  
Muscle Actin ◽  
Ventricular Noncompaction ◽  
Purkinje Fibers ◽  
Histiocytoid Cardiomyopathy ◽  
Pathologic Findings

In a 2-month-old female savannah kitten that died unexpectedly, the pathologic findings of significance were restricted to the heart and included abnormal Purkinje fibers and biventricular myocardial trabeculation or noncompaction. The Purkinje fibers were large, angular, and tightly packed. They contained few disorganized myofibrils among a rarified cytoplasm. The fibers were distinct from adjacent myocytes and were immunohistochemically positive for desmin, muscle actin, myoglobin, sarcomeric actin, and chromogranin A. These findings are identical to those that occur in children with histiocytoid cardiomyopathy, a fatal genetic mitochondrial disorder of Purkinje fibers. Ventricular noncompaction likely has a multifactoral cause that results from fetal arrest of ventricular organizational development that might occur in conjunction with, or independent of, histiocytoid cardiomyopathy.

Association of Ventricular Noncompaction and Histiocytoid Cardiomyopathy: Case Report and Review of the Literature

2012 ◽  
Vol 15 (5) ◽  
pp. 397-402 ◽  
Author(s):  
Silvia Planas ◽  
Joan Carles Ferreres ◽  
Joan Balcells ◽  
Marta Garrido ◽  
Santiago Ramón y Cajal ◽  
...  
Keyword(s):  
Case Report ◽  
Review Of The Literature ◽  
Ventricular Noncompaction ◽  
Histiocytoid Cardiomyopathy

A re-examination of late outward plateau currents of cardiac Purkinje fibers

1985 ◽  
Vol 249 (1) ◽  
pp. H108-H121
Author(s):  
J. M. Jaeger ◽  
W. R. Gibbons
Keyword(s):  
Action Potential ◽  
Voltage Clamp ◽  
Critical Role ◽  
Membrane Current ◽  
Purkinje Fiber ◽  
Purkinje Fibers ◽  
Outward Currents ◽  
Cardiac Purkinje Fibers

Two outward currents, IX1 and IX2, are thought to be activated by depolarization of the Purkinje fiber. One of these, IX1, is presently believed to play a critical role in repolarization of the action potential. The IX currents were originally analyzed in voltage-clamp experiments in sheep Purkinje fibers. These experiments were designed to minimize interference by other currents, and it was assumed that changes of the net current were produced entirely by the IX currents. We have tried to repeat the original experiments and the analysis that led to acceptance of the existence and roles of the IX currents, without success. Moreover, tests of how membrane current should behave if the IX current hypothesis is correct did not give satisfactory results. Our data suggest the original conclusions about IX1 and IX2 may need substantial revision.

Slow inward current may produce many results attributed to IX1 in cardiac Purkinje fibers

1985 ◽  
Vol 249 (1) ◽  
pp. H122-H132
Author(s):  
J. M. Jaeger ◽  
W. R. Gibbons
Keyword(s):  
Action Potential ◽  
Outward Current ◽  
Purkinje Fiber ◽  
Slow Inward Current ◽  
Channel Blockers ◽  
Inward Current ◽  
Purkinje Fibers ◽  
Cardiac Purkinje Fibers ◽  
Current Voltage ◽  
Current Voltage Relation

We have tried to answer two fundamental questions concerning the outward current IX1 of cardiac Purkinje fibers. 1) Is it possible that current changes identified as arising from IX1 in voltage-clamp experiments are actually manifestations of changes in the slow inward current (Isi); and 2) is IX1 in fact required to produce the electrical phenomena attributed to it? Isi behavior and the role of IX1 were explored using computer simulation. The Isi model produced current changes during depolarizations and hyperpolarizations from depolarized resting potentials like those attributed to IX1. It also produced a component of "tail currents" that behaved like IX1. If these current changes were analyzed, assuming that an outward current is responsible, the resulting kinetics and current voltage relation would be very similar to the kinetics and current voltage relation reported for IX1. Using the McAllister, Noble, and Tsien formulation of the Purkinje fiber action potential, we found that IX1 is not essential for repolarization of the reconstructed action potential nor is it needed to reproduce interval duration effects and the effects of applied current in that model. Data suggesting that calcium channel blockers reduce IX1 and that catecholamines increase IX1 may be explained as arising from changes in Isi. Thus many manifestations of IX1 can be explained as arising from unanticipated behavior of Isi, and IX1 does not necessarily play a key role in generating Purkinje fiber electrical activity.

Conduction Delay from Purkinje Fiber to Ventricular Muscle Studied with Extracellular Microelectrodes

1971 ◽  
Vol 49 (7) ◽  
pp. 678-684 ◽  
Author(s):  
Akimitsu Kamiyama ◽  
Fumitake Inoue
Keyword(s):  
Electrical Activity ◽  
Action Potentials ◽  
Field Effect ◽  
Field Potential ◽  
Purkinje Fiber ◽  
Conduction Delay ◽  
Action Current ◽  
Purkinje Fibers ◽  
Transmembrane Action Potentials ◽  
The Relationship

The relationship between electrical activity recorded intracellularly and extracellularly was studied in canine right ventricle. When the tip of a microelectrode was placed against a Purkinje fiber the electrical activity obtained had two components. The first component was a sharp diphasic wave which was defined as an action current while the second component was a rounded and flat diphasic wave which was defined as a field potential. Transmembrane action potentials recorded at the same site indicated that the first component was an active membrane current of the Purkinje fiber while the second component was identified as the field effect potential generated by ventricular fibers lying directly under the layer of Purkinje fibers. In areas where the Purkinje fibers were absent only the second component was present. The time delay of approximately 5 ms between the two components represents the conduction delay of the impulse from the Purkinje fiber to the ventricular fiber.

Competency of embryonic cardiomyocytes to undergo Purkinje fiber differentiation is regulated by endothelin receptor expression

Development ◽  
2002 ◽  
Vol 129 (13) ◽  
pp. 3185-3194 ◽  
Author(s):  
Nobuyuki Kanzawa ◽  
Clifton P. Poma ◽  
Kimiko Takebayashi-Suzuki ◽  
Kevin G. Diaz ◽  
John Layliev ◽  
...  
Keyword(s):  
Heart Development ◽  
Ventricular Myocytes ◽  
Expression Profiles ◽  
Receptor Expression ◽  
Biologically Active ◽  
Cardiac Conduction ◽  
Purkinje Fiber ◽  
Rnase Protection ◽  
Purkinje Fibers ◽  
Embryonic Cardiomyocytes

Purkinje fibers of the cardiac conduction system differentiate from heart muscle cells during embryogenesis. In the avian heart, Purkinje fiber differentiation takes place along the endocardium and coronary arteries. To date, only the vascular cytokine endothelin (ET) has been demonstrated to induce embryonic cardiomyocytes to differentiate into Purkinje fibers. This ET-induced Purkinje fiber differentiation is mediated by binding of ET to its transmembrane receptors that are expressed by myocytes. Expression of ET converting enzyme 1, which produces a biologically active ET ligand, begins in cardiac endothelia, both arterial and endocardial, at initiation of conduction cell differentiation and continues throughout heart development. Yet, the ability of cardiomyocytes to convert their phenotype in response to ET declines as embryos mature. Therefore, the loss of responsiveness to the inductive signal appears not to be associated with the level of ET ligand in the heart. This study examines the role of ET receptors in this age-dependent loss of inductive responsiveness and the expression profiles of three different types of ET receptors, ETA, ETB and ETB2, in the embryonic chick heart. Whole-mount in situ hybridization analyses revealed that ETA was ubiquitously expressed in both ventricular and atrial myocardium during heart development, while ETB was predominantly expressed in the atrium and the left ventricle. ETB2 expression was detected in valve leaflets but not in the myocardium. RNase protection assays showed that ventricular expression of ETA and ETB increased until Purkinje fiber differentiation began. Importantly, the levels of both receptor isotypes decreased after this time. Retrovirus-mediated overexpression of ETA in ventricular myocytes in which endogenous ET receptors had been downregulated, enhanced their responsiveness to ET, allowing them to differentiate into conduction cells. These results suggest that the developmentally regulated expression of ET receptors plays a crucial role in determining the competency of ventricular myocytes to respond to inductive ET signaling in the chick embryo.

Electrotonic inhibition and summation of impulse conduction in mammalian Purkinje fibers

1983 ◽  
Vol 245 (1) ◽  
pp. H42-H53 ◽  
Author(s):  
C. Antzelevitch ◽  
G. K. Moe
Keyword(s):  
Voltage Dependence ◽  
Inhibitory Effect ◽  
Purkinje Fiber ◽  
Related Phenomenon ◽  
Frequency Dependent ◽  
Purkinje Fibers ◽  
Impulse Conduction ◽  
Fiber Segment ◽  
Temporal And Spatial ◽  
Proximal Border

Models of electrotonically mediated transmission were created by superfusion of the central fiber segment of a three-compartment Purkinje fiber preparation with either an "ion-free" or "ischemic" solution or by localized application of pressure. The frequency-dependent impairment of impulse conduction across such inexcitable gaps was found to be the result of influences exerted not only by impulses transmitted across the area of block but also by impulses blocked at the proximal border of the inexcitable zone. The electrotonic image of a nonconducted response was observed to exert an important inhibitory effect on the electronically mediated transmission of a subsequent impulse, thus causing block or delay. This phenomenon, which we have termed electrotonic inhibition, shows both time and voltage dependence. The related phenomenon of electrotonic summation describes the facilitation of conduction that occurs when two subthreshold potentials occur close enough in time to fuse. These data provide a demonstration of Wedensky inhibition in heart tissues and point to electrotonic inhibition as a mechanism of concealed conduction. Electrotonically mediated phenomena may explain both temporal and spatial inhibition and summation previously described in nodal or depressed tissues and ascribed to partial active invasion of intermediary tissue.

Mechanism of facilitation of conduction in Purkinje fibers with sequential pacing

1989 ◽  
Vol 67 (6) ◽  
pp. 650-655
Author(s):  
Patrick Tchou ◽  
Paul Martin ◽  
Don W. Wallick ◽  
William A. Crafford
Keyword(s):  
Clinical Studies ◽  
Cardiac Electrophysiology ◽  
Purkinje Fiber ◽  
Conduction Delay ◽  
Purkinje Fibers ◽  
Purkinje System ◽  
Sequential Mode ◽  
Cardiac Excitation ◽  
Retrograde Conduction

Clinical studies have demonstrated that retrograde conduction of a premature beat through the His–Purkinje system can be facilitated by atrioventricular sequential pacing. Several possible mechanisms of facilitation have been proposed. No studies, however, have shown the occurrence of this phenomenon or its mechanism in isolated Purkinje fibers. The present study demonstrated that facilitation of conduction of a premature beat can indeed occur in isolated canine Purkinje fibers during sequential pacing. When a premature beat showed conduction delay during unidirectional pacing, its conduction consistently improved during sequential pacing. This improvement of conduction was related to a greater membrane recovery of a portion of the Purkinje fiber, i.e., the portion that was pre-excited by the sequential mode of stimulation. These findings suggest that an important mechanism of the facilitation of conduction observed clinically may be similar; i.e., pre-excitation and consequent earlier recovery from refractoriness of portions of the His–Purkinje system during atrioventricular sequential pacing.Key words: cardiac electrophysiology, cardiac excitation, supernormal conduction, cardiac refractoriness, atrioventricular sequential pacing.

Prevention of ischemic ventricular tachycardia of Purkinje origin: role for α2-adrenoceptors in Purkinje?

2001 ◽  
Vol 280 (3) ◽  
pp. H1182-H1190 ◽  
Author(s):  
David O. Arnar ◽  
Dezhi Xing ◽  
Hon-Chi Lee ◽  
James B. Martins
Keyword(s):  
Ventricular Tachycardia ◽  
Coronary Artery ◽  
Adrenergic Receptors ◽  
Purkinje Fiber ◽  
Adrenergic Agonists ◽  
Purkinje Fibers ◽  
Mapping System ◽  
Pharmacological Stimulation ◽  
Uk 14,304 ◽  
Stimulation Of

Recent studies have shown the presence of postjunctional α2-adrenergic receptors on canine Purkinje fibers but not muscle cells. Stimulation of these receptors results in prolongation of the action potential duration and the Purkinje relative refractory period. We studied the effect of α2-adrenergic agonists on inducible ischemic ventricular tachycardia (VT) of both Purkinje fiber and myocardial origin. Open-chest dogs in whom VT was induced with extrastimuli after occlusion of the anterior descending coronary artery were studied. A mapping system, incorporating Purkinje signals, characterized the mechanisms of VT. The α2-adrenergic agonists clonidine (0.5–4.0 μg/kg) or UK 14,304 (4–5 μg/kg) versus saline were given intravenously after reproducibility of inducible sustained monomorphic VT had been demonstrated. Eighteen dogs were given clonidine, eleven of which had focal Purkinje VT. Of these 11 dogs, clonidine blocked VT induction in 9 (81.9%) and rendered VT nonsustained in 1 (9.1%), and VT remained inducible in 1 dog (9.1%), although this was focal midmyocardial VT only. In the seven dogs with VT of myocardial origin, six (85.6%) remained inducible with clonidine, whereas one dog (14.4%) had only nonsustained VT after clonidine. Of the six dogs, UK 14,304 blocked VT induction in four (66.6%) and rendered VT nonsustained in one (16.7%), and VT remained inducible in one dog (16.7%). In four dogs with VT of myocardial origin, VT remained inducible. In the eight control dogs that were given saline, focal Purkinje VT was repeatedly inducible. Pharmacological stimulation of postjunctional α2-adrenoceptors on Purkinje fibers may selectively prevent induction of VT of Purkinje fiber origin in the ischemic canine ventricle.

Effects of chemical subendocardial ablation on activation rate gradient during ventricular fibrillation

1995 ◽  
Vol 269 (6) ◽  
pp. H1998-H2009 ◽  
Author(s):  
Y. M. Cha ◽  
T. Uchida ◽  
P. L. Wolf ◽  
B. B. Peters ◽  
M. C. Fishbein ◽  
...  
Keyword(s):  
Ventricular Fibrillation ◽  
Action Potentials ◽  
Ventricular Myocytes ◽  
Purkinje Fiber ◽  
In Vivo Studies ◽  
Purkinje Fibers ◽  
Activation Rate ◽  
Rate Gradient

The mechanism by which an endocardial-epicardial activation rate gradient develops after 1 or 2 min of sustained ventricular fibrillation is unknown. We recorded from electrodes on the epicardium and from hook electrodes in the endocardium in three open-chest control dogs during prolonged ventricular fibrillation. The same recordings were also made in seven dogs after right ventricular subendocardial ablation with Lugol solution and in three dogs after substitution of air for the cavitary blood. The effects of these interventions, i.e., Lugol ablation (n = 2) and the exposure to air (n = 2), on the subendocardial Purkinje fiber transmembrane action potential properties were also evaluated in vitro using microelectrode recording techniques. The in vivo studies showed a significant endocardial-epicardial rate gradient in the control dogs and in dogs that had air substituted for the cavitary blood. In comparison, in dogs that underwent chemical subendocardial ablation, the activation cycle lengths for the endocardium and epicardium were not significantly different. The in vitro studies showed that subendocardial Purkinje fiber action potentials could still be recorded for up to 10 min of exposure to air. In comparison, in the tissues subjected to chemical ablation, no transmembrane action potentials could be recorded from either the Purkinje fibers or superficial ventricular muscle cells. We conclude that the development of an endocardial-epicardial activation rate gradient during prolonged ventricular fibrillation depends on the presence of intact subendocardial Purkinje fibers and ventricular myocytes. The retained cavitary blood is not responsible for the development of the rate gradient.

Histiocytoid Cardiomyopathy: Three New Cases and a Review of the Literature

1998 ◽  
Vol 1 (1) ◽  
pp. 56-69 ◽  
Author(s):  
Bahig M. Shehata ◽  
Kathleen Patterson ◽  
Jean E. Thomas ◽  
Diane Scala-Barnett ◽  
Sarada Dasu ◽  
...  
Keyword(s):  
Sudden Death ◽  
Lipid Droplets ◽  
Review Of The Literature ◽  
Ultrastructural Examination ◽  
The Third ◽  
Histiocytoid Cardiomyopathy ◽  
Pathologic Findings ◽  
Gross Lesions ◽  
Abnormal Mitochondria ◽  
In Infants And Children

Histiocytoid cardiomyopathy (HC), a rare arrhythmogenic disorder, presents as difficult-to-control arrhythmias or sudden death in infants and children, particularly girls. Three cases are described with autopsy findings. In two cases, yellow-tan nodules were grossly visible in the myocardium; in the third case, no gross lesions were identified. Microscopic examination in all three cases revealed multiple, scattered clusters of histiocytoid myocytes which on ultrastructural examination were filled with abnormal mitochondria, scattered lipid droplets, and scanty myofibrils. These pathologic findings are similar to those previously described. The pathogenesis of this entity remains controversial. It was recently proposed that this disorder is X-linked dominant with the associated gene located in the region of Xp22.

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