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Investigaton and assessment of ejection murmurs and the left ventricular outflow tract in Boxer dogs

Koplitz, Shianne L, DVM
http://rave.ohiolink.edu/etdc/view?acc_num=osu1123596533

Abstract Details

2005, Doctor of Philosophy, Ohio State University, Veterinary Clinical Sciences.
Aortic stenosis (AS) is a common, heritable congenital heart defect affecting Boxer dogs. Veterinarians screen for AS through auscultation. When a typical murmur is auscultated, an echocardiogram identifies the presence and severity of the defect. In the setting of a soft murmur, echocardiographic imaging lesions are often absent, and a noninvasive diagnosis is based on Doppler-identification of high velocity flow across the left ventricular outflow tract (LVOT). However, similar increases in LVOT velocity and cardiac murmurs can occur in normal dogs under sympathetic stimulation. We hypothesized that boxers with ejection murmurs and elevated LVOT velocities have AS. Specific aims were to characterize the relationship between these murmurs and velocities; to evaluate LVOT morphology with echocardiography and angiography; to compare stroke volumes between boxers with and without murmurs; to evaluate pressure gradients across the LVOT for evidence of stenosis under different hemodynamic circumstances; and to identify the site of murmur generation with intracardiac phonocardiography. Of 201 healthy adult boxers, over 50% had left basilar ejection murmurs typical of AS, and 36% demonstrated both a murmur and elevated LVOT velocity. The presence of a murmur predicted a velocity > 2 m/s, with an 87% sensitivity and 66% specificity. Indexed echocardiographic diameters and areas were not different between boxers with ejection murmurs and boxers without murmurs, although they were smaller than in non-boxer dogs. Boxers with murmurs tended to have higher stroke volumes. Angiographically, the LVOT in boxers was diffusely smaller than non-boxers, with substantial narrowing at the sinus of Valsalva Pressure recordings were typical of impulse gradients and significant peak to peak gradients were not found. Intracardiac phonocardiography identified the distal LVOT as the site of murmur generation. The etiology of ejection murmurs and elevated LVOT velocities in boxers is multi-factorial. The relatively smaller LVOT likely predisposes boxers, while the stroke volume helps determine the presence or absence of an ejection murmur and elevated velocity in individual dogs. The relationship of a diffusely smaller LVOT to the more typical discrete stenotic lesions that characterize AS requires further study.
Kathryn Meurs (Advisor)
133 p.
Aortic stenosis; Boxer; Left ventricular outflow tract; Angiography; Echocardiography; Intracardiac phonocardiography; Ejection murmur; Functional murmur; Physiologic murmur; Veterinary cardiology

Recommended Citations

Citations

  • Koplitz, DVM, S. L. (2005). Investigaton and assessment of ejection murmurs and the left ventricular outflow tract in Boxer dogs [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1123596533

    APA Style (7th edition)

  • Koplitz, DVM, Shianne. Investigaton and assessment of ejection murmurs and the left ventricular outflow tract in Boxer dogs. 2005. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1123596533.

    MLA Style (8th edition)

  • Koplitz, DVM, Shianne. "Investigaton and assessment of ejection murmurs and the left ventricular outflow tract in Boxer dogs." Doctoral dissertation, Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1123596533

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.