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An investigation of the second heart sound in the normal horse
Author(s) -
WELKER F. H.,
MUIR W. W.
Publication year - 1990
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/j.2042-3306.1990.tb04304.x
Subject(s) - intracardiac injection , horse , medicine , sound (geography) , heart sounds , cardiology , anatomy , acoustics , physics , biology , paleontology
Summary The second heart sound was evaluated in conscious, normal horses using intracardiac and external sound detection devices and echocardiography. The second heart sound (S 2 ) in the normal horse is single or split by a narrow interval, not usually detected by external phonocardiographic evaluation. Splitting of S 2 was classified as normal (aortic [A 2 ] preceding pulmonic [P 2 ] components) in 66.7 per cent and reversed (P 2 preceding A 2 ) in 33.3 per cent of the horses studied. Normal splitting appears to result from lower impedance of the pulmonary vasculature delaying the onset of P 2 . Reverse splitting appears to result from a delay in A 2 resulting from prolongation of PEP and LVET. There does not appear to be variation in splitting of S 2 due to respiration based on the cases in which this was measured.