HEART SOUNDS AND MURMURS - CHANGES RELATED TO SEVERITY OF CHRONIC VALVULAR DISEASE IN THE CAVALIER-KING-CHARLES-SPANIEL

Auscultatory, phonocardiographic (PCG), radiographic, and echocardiogr aphic evidence of chronic valvular disease (CVD) were studied in 79 Ca valier King Charles Spaniels with a mean age of 7.6 years (SD 2.6). Ca rdiac murmurs were present in 59 of the dogs and the intensity of the systolic cardiac murmur, assessed by auscultation (grade 1-6), was cor related (P < .001) to the severity of CVD (heart failure class) and to the echocardiographical dimensions of the heart (left atrial ratio, L a/Ao-d, and left ventricular end diastolic diameter, LVEDD) (both P < .001). The heart sounds and duration of electromechanical systole (Q-S 2) were investigated in all dogs using measurements obtained from PCG recordings. Normal regression equations describing the relation betwee n heart rate and systolic intervals (Q-S1, Q-S2 and S1-S2) were establ ished 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 reg ression 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 o f the amplitudes of the first (S1) and second heart sounds (S2) measur ed on the PCG recordings was found to be increased in dogs belonging t o 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 S 1a/ S2a ratio was described by quadratic regression and found to be si gnificant for both parameters (LVEDD: P < .001, R(2) = .54 and La/Ao-d ; P < .001, R(2) = .63). The presence of a third heart sound (S3) was detected, using PCG, in 21 of the 68 dogs. The proportion of dogs exhi biting 83 increased with heart failure class (and increasing cardiac d imensions) (P < .001). These findings were confirmed by observations i n 13 Cavalier King Charles Spaniels with cardiac failure progressing f rom 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 a mplitudes of S1 and S2, as well as a shortening in Q-S2 and S1-S2 inte rvals (all P < .01) were found in these dogs. None of these dogs showe d an S3 in heart failure class I, but 7 of the 13 dogs developed an S3 in class II.