title: Doppler echocardiographic evaluation of midventricular obstruction in cats with hypertrophic cardiomyopathy.
abstract: BACKGROUND
  Hypertrophic cardiomyopathy (HCM) is heterogeneous in both people and cats, with variability in the distribution of hypertrophy, hemodynamic characteristics, and Doppler echocardiographic findings.
  
  
  OBJECTIVE
  To document the Doppler echocardiographic characteristics of midventricular obstruction in some cats with HCM.
  
  
  METHODS
  Eight cats with hypertrophic cardiomyopathy.
  
  
  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
  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.
authors.affiliation: Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO.
authors.forename: H B
authors.initials: HB
authors.lastname: MacLea
authors.forename: J A
authors.initials: JA
authors.lastname: Boon
authors.forename: J M
authors.initials: JM
authors.lastname: Bright
mesh_terms: D000818:Animals; D002312:Cardiomyopathy, Hypertrophic / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000662:veterinary*; D002371:Cat Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002415:Cats; D005260:Female; D017379:Hypertrophy, Left Ventricular / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000662:veterinary*; D008297:Male; D012189:Retrospective Studies; D018615:Ultrasonography, Doppler, Color / Q000662:veterinary
keywords: Echocardiography; Feline; HCM; Midventricle