Document Detail


Effect of myocardial fiber direction on epicardial potentials.
MedLine Citation:
PMID:  7994857     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND: Understanding the relations between the architecture of myocardial fibers, the spread of excitation, and the associated ECG signals is necessary for addressing the forward problem of electrocardiography, that is, predicting intracardiac and extracardiac ECGs from known intracardiac activity. So far, these relations have been studied experimentally only in small myocardial areas. In this study, we tested the hypothesis that potential distributions measured over extensive epicardial regions during paced beats reflect the direction of superficial and intramural fibers through which excitation is spreading in both the initial and later stages of ventricular excitation. We also tried to establish whether the features of the epicardial potential distribution that correlate with fiber direction vary as a function of pacing site, intramural pacing depth, and time elapsed after the stimulus. An additional purpose was to compare measured epicardial potentials with recently published numerical simulations depicting the three-dimensional spread of excitation in the heart muscle and the associated potential fields. METHODS AND RESULTS: The hearts of 18 mongrel dogs were exposed and 182 to 744 unipolar electrograms were recorded from epicardial electrode arrays (2.3 x 3.0 to 6.5 x 6.5 cm). Hearts were paced at various intramural depths through an intramural needle. The overall number of pacing sites in 18 dogs was 241. Epicardial potential distributions, electrographic waveforms, and excitation time maps were displayed, and fiber directions in the ventricular wall underlying the electrodes were determined histologically. During the early stages of ventricular excitation, the position of the epicardial maxima and minima revealed the orientation of myocardial fibers near the pacing site in all cases of epicardial and intramural pacing and in 60% of cases of endocardial or subendocardial pacing. During later stages of propagation, the rotation and expansion of the positive areas correlated with the helical spread of excitation through intramurally rotating fibers. Marked asymmetry of potential patterns probably reflected epicardial-endocardial obliqueness of intramural fibers. Multiple maxima appeared in the expanding positive areas. CONCLUSIONS: For 93% of pacing sites, results verified our hypothesis that epicardial potential patterns elicited by ventricular pacing reflect the direction of fibers through which excitation is spreading during both the initial and later stages of propagation. Epicardial potential distributions provided information on the site of origin and subsequent helical spread of excitation in an epicardial-endocardial, endocardial-epicardial, or double direction. Results were in agreement with previously published numerical simulations except for the asymmetry and fragmentation of the positive areas.
Authors:
B Taccardi; E Macchi; R L Lux; P R Ershler; S Spaggiari; S Baruffi; Y Vyhmeister
Related Documents :
3377317 - Influence of alterations in heart rate on echocardiographic measurements in the dog.
10087547 - Hemodynamic effect of rapid atrial pacing in fetal lambs.
19147457 - Heart rate per se impacts cardiac function in patients with systolic heart failure and ...
2441367 - Antiarrhythmic effects of vvi pacing at physiologic rates: a crossover controlled evalu...
18638777 - Tissue rescue therapy for acute ischaemic stroke.
10716527 - A case of aortic dissection with transient st-segment elevation due to functional left ...
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Circulation     Volume:  90     ISSN:  0009-7322     ISO Abbreviation:  Circulation     Publication Date:  1994 Dec 
Date Detail:
Created Date:  1995-01-17     Completed Date:  1995-01-17     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0147763     Medline TA:  Circulation     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  3076-90     Citation Subset:  AIM; IM    
Affiliation:
Nora Eccles Harrison Cardiovascular Research and Training Institute, Utah University Medical School, Salt Lake City.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Descriptor/Qualifier:
Animals
Cardiac Pacing, Artificial / methods
Dogs
Electric Stimulation
Electrocardiography
Electrophysiology
Heart / physiology*
Muscle Fibers, Skeletal / physiology*
Pericardium / physiology*
Rotation
Ventricular Function
Grant Support
ID/Acronym/Agency:
R01-HL-43276-04/HL/NHLBI NIH HHS

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


Previous Document:  Observations of ventilation during resuscitation in a canine model.
Next Document:  Suppression of thrombolysis in a canine model of pulmonary embolism.