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Titolo:
THE INFLUENCE OF MYOCARDIAL SYSTOLIC SHORTENING ON ACTION-POTENTIAL DURATION FOLLOWING CHANGES IN LEFT-VENTRICULAR END-DIASTOLIC PRESSURE
Autore:
COULSHED DS; HAINSWORTH R; COWAN JC;
Indirizzi:
NEPEAN HOSP,DEPT CARDIOL,CLIN SCI BLDG,POB 63 PENRITH NSW 2751 AUSTRALIA UNIV LEEDS,ACAD DEPT CLIN MED LEEDS W YORKSHIRE ENGLAND
Titolo Testata:
Journal of cardiovascular electrophysiology
fascicolo: 11, volume: 5, anno: 1994,
pagine: 919 - 932
SICI:
1045-3873(1994)5:11<919:TIOMSS>2.0.ZU;2-Z
Fonte:
ISI
Lingua:
ENG
Soggetto:
CONGESTIVE HEART-FAILURE; MECHANOELECTRICAL FEEDBACK; CANINE HEARTS; INTACT HEART; VOLUME LOAD; INSITU; ARRHYTHMIA; AFTERLOAD; PRELOAD; CONTRACTILITY;
Keywords:
CONTRACTION EXCITATION FEEDBACK; HEMODYNAMICS; ACTION POTENTIALS; ARRHYTHMIAS; HEART FAILURE; GUINEA PIGS; DOGS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
32
Recensione:
Indirizzi per estratti:
Citazione:
D.S. Coulshed et al., "THE INFLUENCE OF MYOCARDIAL SYSTOLIC SHORTENING ON ACTION-POTENTIAL DURATION FOLLOWING CHANGES IN LEFT-VENTRICULAR END-DIASTOLIC PRESSURE", Journal of cardiovascular electrophysiology, 5(11), 1994, pp. 919-932

Abstract

Introduction: Contraction-excitation feedback may be an important factor in arrhythmogenesis in patients with heart failure. We have previously demonstrated the contrasting effects of raising left ventricular end-diastolic pressure on action potential duration in dog and guinea pig hearts. The current study was undertaken to assess whether these differing effects might reflect differences in the effect of varying left ventricular end-diastolic pressure on systolic shortening in the two models. Methods and Results: Two models were studied and compared. In open chest dog hearts and isolated guinea pig hearts, measurements of myocardial segment length were made while left ventricular end-diastolic pressure was raised and lowered at constant left ventricular peaksystolic pressure. Action potentials were also recorded while left ventricular end-diastolic pressure was changed. The dog hearts were studied further in a manner aimed at reproducing the contraction pattern of the guinea pig hearts. In the in situ dog heart, elevation of left ventricular end-diastolic pressure, and the consequent increase in end-diastolic segment length, was accompanied by a marked increase in systolic shortening, such that minimum systolic segment length remained unchanged. Elevation of left ventricular end-diastolic pressure was accompanied by a prolongation of action potential duration. In the in vitro guinea pig model, elevation of left ventricular end-diastolic pressure was accompanied by more modest changes in systolic shortening, which were not sufficient to compensate for increased diastolic segment length. Consequently, minimum systolic segment length increased as the hearts dilated. Elevation of left ventricular end-diastolic pressure was accompanied by a shortening of action potential duration. In a further series of experiments, the effects of increased left ventricular end-diastolic pressure were studied in the dog model while allowing aortic pressure to rise, thereby restricting systolic shortening. Under these circumstances, the dog model was similar to the guinea pig model, with an increase in left ventricular end-diastolic pressure causing a shortening of action potential duration. Conclusion: Our results suggest that the effects of preload changes on action potential duration depend on accompanying changes in systolic shortening. This suggests a possible role for contraction-excitation feedback in arrhythmogenesis in patients with regional wall-motion abnormalities.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 24/11/20 alle ore 22:50:34