Basis for Ventricular Arrhythmias Accompanying Myocardial Infarction

Wit, Andrew L.; Friedman, Peter L.

doi:10.1001/archinte.1975.00330030109011

Cited by 54 publications

(5 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Transmurality of the infarct was reduced at the borderzones. A pink rim of surviving myocardium was seen at the epicardial borderzone as with other MI models (14,15,20,22,23,48,66,68) (Fig. 1D).…”

Section: Resultssupporting

confidence: 59%

A novel, minimally invasive, segmental myocardial infarction with a clear healed infarct borderzone in rabbits

Ziv

Schofield

Lau

et al. 2012

American Journal of Physiology-Heart and Circulatory Physiology

View full text Add to dashboard Cite

G. A novel, minimally invasive, segmental myocardial infarction with a clear healed infarct borderzone in rabbits. Am J Physiol Heart Circ Physiol 302: H2321-H2330, 2012. First published March 23, 2012 doi:10.1152/ajpheart.00031.2012.-Ventricular arrhythmias in the setting of a healed myocardial infarction have been studied to a much lesser degree than acute and subacute infarction, due to the pericardial scarring, which results from the traditional open-chest techniques used for myocardial infarction (MI) induction. We sought to develop a segmental MI with low perioperative mortality in the rabbit that allows optimal visualization and therefore improved study of the infarction borderzone. Rabbits underwent MI using endovascular coil occlusion of the first obtuse marginal artery. Three weeks postprocedure, we evaluated our model by echocardiography and electrophysiology studies, optical mapping of isolated hearts, and histological studies. Seventeen rabbits underwent the protocol (12 MI and 5 sham) with a 92% survival to completion of the study (11 MI and 5 sham). MI rabbits demonstrated wall motion abnormalities on echocardiography while shams did not. At electrophysiological study, two MI rabbits had inducible ventricular tachycardia and one had inducible ventricular fibrillation. Isolated hearts demonstrated no pericardial scarring with a smooth, easily identifiable infarct borderzone. Optical mapping of the borderzone region showed successful mapping of peri-infarct reentry formation, with ventricular fibrillation inducible in 11 of 11 MI hearts and 1 of 5 sham hearts. We demonstrate successful high resolution mapping in the borderzone, showing delayed conduction in this region corresponding to late deflections in the QRS on ECG. We report the successful development of a minimally invasive MI via targeted coil delivery to the obtuse marginal artery with an exceptionally high rate of procedural survival and an arrhythmogenic phenotype. This model mimics human post-MI on echocardiography, gross pathology, histology, and electrophysiology.arrhythmia; optical mapping; ventricular tachycardia SUDDEN CARDIAC DEATH (SCD) remains a major public health issue constituting an estimated 20% of deaths in industrialized countries (31,40,49). In autopsy series, nearly 50% of SCD victims have had healed myocardial infarction (MI; Refs. 24, 69). The majority of sudden deaths after MI occur due to ventricular tachyarrhythmias (26). Post-MI ventricular arrhythmias have been studied extensively in animal models. The animal studies suggest the epicardial borderzone as a key player in the formation of reentrant ventricular tachyarrhythmias due to changes in tissue structure, ion channels, and gap junctions that slow conduction and generate anisotropy (6,21,22,35,47,65,67). While these studies have greatly enhanced our understanding of post-MI arrhythmias, our understanding of the arrhythmia mechanisms in healed infarct remains limited because most of studies used 5 days postinfarction, not a fully healed post-MI heart. In additio...

show abstract

Section: Resultssupporting

confidence: 59%

A novel, minimally invasive, segmental myocardial infarction with a clear healed infarct borderzone in rabbits

Ziv

Schofield

Lau

et al. 2012

American Journal of Physiology-Heart and Circulatory Physiology

View full text Add to dashboard Cite

show abstract

“…If the slow inward current plays an important role during ischemia, then it is conceivable that the duration of refractoriness could outlast full repolarization of the action potential. 29 " 31 However, postrepolarization refractoriness may not be the exclusive property of the slow response.…”

mentioning

confidence: 99%

Alterations in canine myocardial excitability during ischemia.

Elharrar

Foster

Jirak

et al. 1977

Circulation Research

150

View full text Add to dashboard Cite

The effect of the cardiac membrane potential on the rapid availability of the sodium-carrying system. J Physiol (Lond) 127: 213-224, 1955 20 Alterations in Canine Myocardial Excitability during Ischemia VICTOR ELHARRAR, PETER R. FOSTER, THOMAS L. JIRAK, WINSTON E. GAUM, AND DOUGLAS P. ZIPES SUMMARY Changes in the ventricular diastolic excitability threshold following occlusion of the left anterior descending coronary artery (LAD)were studied in open-chest anesthetized dogs by using a new automatic threshold-following pacemaker (ATFP). The ATFP measures the diastolic excitability threshold by successively decreasing the duration of regularly occurring pacing stimuli until the ventricle fails to respond. Under control conditions, the threshold stimulus duration was 60 ± 4 (mean ± SEM) /Lisec. In the first 1-3 minutes following occlusion of the LAD, the diastolic excitability threshold in the ischemic zone (IZ) decreased to 51 ± 5 fisec and then rapidly increased to 600 pisec at 5 minutes. The initial decrease in excitability threshold at IZ could be abolished by elevating the serum K + concentration prior to the LAD occlusion. These changes in excitability threshold at IZ could be prevented by infusing nonoxygenated solutions into the LAD at a site distal to the occlusion. As the excitability threshold increased in IZ during ischemia, the earliest time at which IZ could be reactivated by a stimulus with a voltage equal to twice the preligation diastolic voltage threshold was increased. In nine of 16 dogs, after 5 minutes of LAD ligation, the IZ to normal zone (NZ) activation time (when stimulating at IZ) exceeded the NZ to IZ activation time (when stimulating at NZ) by an average of 9 msec. We also found that in four dogs the NZ to IZ activation time exceeded the IZ to NZ activation time by an average of 10 msec. We conclude from these findings that a gradient of increasing excitability threshold exists as one moves from normally perfused toward more ischemic tissue, passing through a heterogeneous border zone that manifests some areas which have a decreased excitability threshold and other areas which have an increased excitability threshold, and that these changes in excitability importantly influence the determination of refractory period durations and conduction times.SEVERAL investigators have examined changes in refractory period duration and conduction that accompany

show abstract

“…In the normal heart with a normal vascular bed and an intact autoregulation, this increased consumption is easily compensated for by an increased blood flow (3) and no regions of the heart are thus rendered hypoxic. In the diseased heart, however, increased oxygen requirements may be able to provoke focal ischemia and, hence, arrhythmias (16) fasting (Fig. 1).…”

Section: Resultsmentioning

confidence: 99%

Influence of High Plasma Concentrations of Free Fatty Acids on Heart Rhythm in Healthy Fasting Men

Wang

Rasmussen

Vik‐Mo

et al. 1979

Journal of Internal Medicine

View full text Add to dashboard Cite

ABSTRACT. Ten healthy male students in regular sinus rhythm fasted for 66 hours. Their overnight fasting plasma concentration of free fatty acids (FFA) was 455±104 μmol/l (mean ± S.E.M., n=7), the reference value of our laboratory, measured in another normal population of young men, being 344±28 μmol/l (n = 10). After 42 and 66 hours of fasting, the plasma concentration of FFA rose to 1198±181 (p>0.01, n=10) and 1471±89 μmol/l (p>0.001, n = 10), respectively. During the last 24 hours of fasting, the heart rhythm was monitored continuously by means of a Holter recorder and computer. No arrhythmias were observed, indicating that elevated plasma concentrations of FFA, exceeding those reported in patients with acute myocardial infarction, are well tolerated by the healthy human myocardium.

show abstract

Basis for Ventricular Arrhythmias Accompanying Myocardial Infarction

Cited by 54 publications

References 25 publications

A novel, minimally invasive, segmental myocardial infarction with a clear healed infarct borderzone in rabbits

A novel, minimally invasive, segmental myocardial infarction with a clear healed infarct borderzone in rabbits

Alterations in canine myocardial excitability during ischemia.

Influence of High Plasma Concentrations of Free Fatty Acids on Heart Rhythm in Healthy Fasting Men

Contact Info

Product

Resources

About