Echocardiographic estimation of mean left atrial pressure in a canine model of acute mitral valve insufficiency.

TitleEchocardiographic estimation of mean left atrial pressure in a canine model of acute mitral valve insufficiency.
Publication TypeJournal Article
Year of Publication2004
AuthorsOyama MA, Sisson DD, Bulmer BJ, Constable PD
JournalJournal of veterinary internal medicine / American College of Veterinary Internal Medicine
Volume18
Issue5
Pagination667-72
Date Published2004 Sep-Oct
ISSN0891-6640
KeywordsAnimals, Atrial Function, Left, Blood Flow Velocity, Catheterization, Swan-Ganz, Disease Models, Animal, Dog Diseases, Dogs, Echocardiography, Doppler, Heart Atria, Hemodynamics, Mitral Valve Insufficiency, Systole
Abstract

High mean left atrial pressure (MLAP) due to canine degenerative mitral valve disease is associated with clinically relevant morbidity and mortality. The ability to noninvasively measure MLAP would assist in the diagnosis and treatment of disease. Doppler echocardiography allows measurement of early transmitral blood flow (E) and the velocity of the mitral valve annulus (Ea). The ratio of early mitral inflow velocity to early mitral annular velocity (E: Ea) correlates well with MLAP in human subjects. We sought to determine the ability of E: Ea to predict MLAP in dogs with experimentally induced mitral regurgitation. Nine anesthetized purpose-bred dogs underwent placement of a Swan-Ganz catheter into the left atrium and recording of MLAP. Simultaneous transthoracic echocardiographic and hemodynamic studies were performed after acute chordae tendineae rupture and during IV infusion with nitroprusside (2.5-5.0 microg x kg(-1) x min(-1)) or hydralazine (1-1.5 mg/kg). Mitral regurgitant fraction, measured by single-plane angiography and thermodilution, ranged from 17% to 81%. MLAP increased from 5.4 +/- 2.5 mm Hg to 17.4 +/- 9.4 mm Hg after creation of mitral valve regurgitation (MR; P = .018). Forty sets of echocardiographic measurements were obtained from 7 dogs, and E, as well as E: Ea, were linearly related to MLAP. The R2 value for the linear regression equation containing E: Ea as the dependent variable (0.83) was greater than that for E (0.73). The 95% confidence intervals were calculated for predicting MLAP = 20 mm Hg from E:Ea, and E:Ea >9.1 or <6.0 indicated a 95% probability that MLAP was >20 mm Hg or <20 mm Hg, respectively. Echocardiography can be used to predict MLAP in isoflurane-anesthetized dogs with experimentally induced acute mitral valve insufficiency.

Alternate JournalJ. Vet. Intern. Med.