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) t o the severity of CVD (heart failure class) and t o the echocardiographical 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 (042) were investigated in all dogs using measurements obtained from PCG recordings. Normal regression equations describing the relation between heart rate and systolic intervals (Q-Sl, Q-S2 and Sl-S2) were established based on observations in 1 1 normal control Cavalier King Charles Spaniels. The total electromechanical systole (Q-S2). 0-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 t o heart failure class I (Q-S2; P < .01 and S1 -S2; P < .05), class II, and classes Ill and IV (both P < ,001). The ratio of the amplitudes of the first (SI) and second heart hronic valvular disease (CVD) is commonly ob-C served in old dogs of small to medium size breeds.'-3 Lesions associated with CVD start with a progressive thickening and contraction of the atrioventricular valves leading to insufficient coaptation of the leaflets. This causes an increasing regurgitation of blood with accompanying enlargement of the atrium and ventricle. The areas of contact along the free border of the mitral cusps and corresponding chordae tendineae are commonly a f f e~t e d ,~ but the tricuspid valves can also display pathological changes; the pulmonary and aortic valves are seldom affe~ted.~ The animal can compensate for the valvular insufficiency for a period of time, but decompensation and, usually, left-sided congestive heart failure may ultimately desounds (S2) measured on the PCG recordings was found t o be increased in dogs belonging t o class I (P < .Ol), class II, and classes 111 and IV (both P < .OOl). The relationship between cardiac dimensions (LVEDD and La/Ao-d) and Sla/ 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 13Cavalier King Charles Spaniels with cardiac failure progressing from heart failure class I toclass II (Mean LVEDDfrom Ao-d from 1.09 t o 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 in...

Survival Characteristics and Prognostic Variables of Dogs with Mitral Regurgitation Attributable to Myxomatous Valve Disease

“…This is in agreement with previous studies. 1,32 However, age was not an independent prognostic variable in multivariate analysis, presumably because this variable was highly covariate with severity of MR.…”

Finding cardiovascular disease genes in the dog

“…Extensive breeding studies performed on a family of poodles segregating Patent ductus arteriosus suggest that, at least in this breed, it is inherited as a polygenic defect 1,4 . Molecular studies have suggested that multiple genes contribute to the development of myxomatous valve disease in the Cavalier King Charles Spaniels and Dachshunds 8,9 and the conotruncal heart defect in the Keeshond dog 43 .…”

“…Although the true prevalence of heart disease in dogs is unknown, two independent studies completed 30 years apart suggest that approximately 11% of canine patients presenting for evaluation at large veterinary hospitals have cardiac disease 6,7 . Many of the most common congenital and adult onset cardiovascular diseases are familial, in at least some breeds (Table 1), including myxomatous valve disease in the Cavalier King Charles Spaniel 8 and Dachshunds 9 and dilated cardiomyopathy in the Doberman Pinscher, Great Dane and Portuguese Water Dog [10][11][12] . In many other cases, a subset of breeds have been suggested to have an elevated relative risk compared to the general canine population indicating a familial nature of the disease though genetic studies are required to confirm this ( Figure 1).…”

Myxomatous Mitral Valve Disease in Dogs - an Update and Perspectives

“…Murmurs can provide valuable information regarding disease severity; the intensity of the murmur correlates with the severity of MMVD and heart failure class. An increase in the intensity of the S1 sound and a decrease of the S2 sound with the presence of S3 sound are signs of moderate to severe MMVD (9). A right-side murmur can indicate the radiation of a loud mitral murmur to the right side or concomitant tricuspid regurgitation and possible pulmonary hypertension (PHT).…”