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Doppler echocardiographic evaluation of midventricular obstruction in cats with hypertrophic cardiomyopathy
H B MacLea1, J A Boon, J M Bright
1Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO.
Insights
Hypertrophic cardiomyopathy (HCM) in cats can present with midventricular obstruction. This study documents its Doppler echocardiographic features, aiding diagnosis in cats with murmurs.
Area of Science:
- Veterinary Cardiology
- Feline Medicine
- Cardiovascular Imaging
Background:
- Hypertrophic cardiomyopathy (HCM) exhibits significant heterogeneity in feline patients.
- Variability exists in hypertrophy distribution, hemodynamics, and echocardiographic findings in cats with HCM.
Purpose of the Study:
- To characterize the Doppler echocardiographic features of midventricular obstruction in cats with HCM.
- To identify a specific variant of feline HCM.
Main Methods:
- Retrospective case series of eight cats with confirmed HCM.
- Analysis of transthoracic two-dimensional, M-mode, and Doppler echocardiography.
- Exclusion of cats with systemic hypertension (systolic blood pressure > 170 mmHg).
Main Results:
- All cats displayed left ventricular hypertrophy at the papillary muscle level and midventricular hypertrophy.
- Doppler echocardiography revealed turbulent midventricular flow in all cases.
- Increased flow velocities and late-peaking flow profiles were observed at the left midventricle.
Conclusions:
- A distinct variant of feline HCM involves hypertrophy at the papillary muscle level causing midventricular obstruction.
- Recognizing this variant is crucial for diagnosing HCM in cats presenting with murmurs and atypical echocardiographic findings.
Background:
Hypertrophic cardiomyopathy (HCM) is heterogeneous in both people and cats, with variability in the distribution of hypertrophy, hemodynamic characteristics, and Doppler echocardiographic findings.
Objectives:
To document the Doppler echocardiographic characteristics of midventricular obstruction in some cats with HCM.
Animals:
Eight cats with hypertrophic cardiomyopathy.
Materials And Methods:
Retrospective case series. The medical records of cats presenting to the cardiology service at Colorado State University between February 2009 and January 2012 were reviewed. All cats had a physical examination; Doppler systolic blood pressure measurement; and transthoracic two-dimensional (2D), M-mode, and Doppler echocardiography were performed. A more thorough evaluation of the echocardiographic images and measurements was performed. Cats included in this study had echocardiograms of adequate quality to confirm the diagnosis of midventricular obstruction by documentation of left midventricular concentric hypertrophy; a midventricular turbulent Doppler color flow pattern; and high velocity, late-peaking flow at the area of turbulence. Cats with evidence of systemic hypertension defined as a systolic Doppler blood pressure of greater than 170 mmHg were excluded.
Results:
All 8 cats had left ventricular hypertrophy at the level of the papillary muscles; left, midventricular hypertrophy; and in 4/8 cats there was apical hypertrophy or basilar hypertrophy of the interventricular septum. Color flow Doppler revealed turbulent flow in 8/8 cats and spectral Doppler (continuous and pulsed wave) revealed increased flow velocities and late-peaking flow profiles at the level of the left midventricle. Two of 8 cats had a bifid midventricular flow profile in which there was a midsystolic decline in left ventricular velocities with elevated velocities extending into early diastole. The peak left ventricular outflow velocity in all 8 cats was normal.
Conclusions And Clinical Importance:
A variant of HCM characterized by hypertrophy at the level of the papillary muscles with midventricular obstruction is present in some cats. Recognition of this variant of feline HCM allows identification of HCM in cats with murmurs where the more classic features of HCM are not present.
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