title: Heart sounds and murmurs: changes related to severity of chronic valvular disease in the Cavalier King Charles spaniel.
abstract: Auscultatory, phonocardiographic (PCG), radiographic, and echocardiographic evidence of chronic valvular disease (CVD) were studied in 79 Cavalier King Charles Spaniels with a mean age of 7.6 years (SD 2.6). Cardiac murmurs were present in 59 of the dogs and the intensity of the systolic cardiac murmur, assessed by auscultation (grade 1-6), was correlated (P < .001) to the severity of CVD (heart failure class) and to the echocardiographic dimensions of the heart (left atrial ratio, La/Ao-d, and left ventricular end diastolic diameter, LVEDD) (both P < .001). The heart sounds and duration of electromechanical systole (Q-S2) were investigated in all dogs using measurements obtained from PCG recordings. Normal regression equations describing the relation between heart rate and systolic intervals (Q-S1, Q-S2 and S1-S2) were established based on observations in 11 normal control Cavalier King Charles Spaniels. The total electromechanical systole (Q-S2), Q-S1, and S1-S2 intervals in the 59 dogs were related to the corresponding normal regression equation. A shortening of Q-S2 and S1-S2 intervals were found in dogs belonging to heart failure class I (Q-S2; P < .01 and S1-S2; P < .05), class II, and classes III and IV (both P < .001). The ratio of the amplitudes of the first (S1) and second heart sounds (S2) measured on the PCG recordings was found to be increased in dogs belonging to class I (P < .01), class II, and classes III and IV (both P < .001). The relationship between cardiac dimensions (LVEDD and La/Ao-d) and S1a/S2a ratio was described by quadratic regression and found to be significant for both parameters (LVEDD; P < .001, R2 = .54 and La/Ao-d; P < .001, R2 = .63). The presence of a third heart sound (S3) was detected, using PCG, in 21 of the 68 dogs. The proportion of dogs exhibiting S3 increased with heart failure class (and increasing cardiac dimensions) (P < .001). These findings were confirmed by observations in 13 Cavalier King Charles Spaniels with cardiac failure progressing from heart failure class I to class II (Mean LVEDD from 30.2 to 35.2 mm and mean La/Ao-d from 1.09 to 1.43). An increase in intensity of the heart murmur, assessed by auscultation, increase in the ratio of the amplitudes of S1 and S2, as well as a shortening in Q-S2 and S1-S2 intervals (all P < .01) were found in these dogs.(ABSTRACT TRUNCATED AT 400 WORDS)
authors.affiliation: Department of Physiology, Swedish University of Agricultural Sciences, Uppsala.
authors.forename: J
authors.initials: J
authors.lastname: Häggström
authors.forename: C
authors.initials: C
authors.lastname: Kvart
authors.forename: K
authors.initials: K
authors.lastname: Hansson
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002908:Chronic Disease; D004283:Dog Diseases / Q000503:physiopathology*; D004285:Dogs; D004452:Echocardiography / Q000662:veterinary; D004562:Electrocardiography / Q000662:veterinary; D005260:Female; D006337:Heart Murmurs / Q000503:physiopathology / Q000662:veterinary*; D006347:Heart Sounds; D006349:Heart Valve Diseases / Q000503:physiopathology / Q000662:veterinary*; D008297:Male; D012720:Severity of Illness Index