Acquired Valvular Disease

Chapter 6 Acquired Valvular Disease



Jonathan A. Abbott




DEGENERATIVE MITRAL VALVE DISEASE


Based on its clinical and pathologic features, numerous designations for degenerative mitral value disease (MVD) have been proposed. The terms myxomatous valvular degeneration, myxomatous transformation, mucoid degeneration, endocardiosis, chronic valvular disease, and degenerative valvular disease all refer to the same disorder.



Prevalence and Incidence













Pathophysiology


















Clinical Presentation



History







Physical Findings




• A high-frequency, mid-systolic click (Figure 6-3) is sometimes heard in older, small-breed dogs. These clicks may be associated with prolapse of the mitral valve. In many dogs, clicks are a precursor of MR. Often, a soft systolic murmur of MR can also be heard in patients that have systolic clicks.









Patients with Mitral Regurgitation and Concurrent Respiratory Tract Disease









Table 6-1 Guidelines for Clinical Assessment of Elderly Small-Breed Dogs With Cough and Cardiac Murmur*























  Cardiac Disease Respiratory Disease
Body condition Thin Obese
Cardiac murmur Loud Often soft, occasionally loud
Heart rate Rapid Normal or slow
Rhythm Regular, unless pathologic arrhythmias are present Exaggerated respiratory arrhythmia may be present

* It is important to recognize that exceptions to these generalities certainly occur. However, when a patient exhibits all of the findings in the left-hand column, it is likely that cardiac disease or, perhaps, congestive heart failure, is responsible for the cough. It must be recognized that some patients have both respiratory tract disease and cardiac disease. Ultimately, the distinction between respiratory tract disease and cardiac is made through diagnostic imaging; thoracic radiographs are indispensable, and echocardiography often provides useful, complementary data.




Diagnostic Findings




Radiographic Appearance of Left Atrial Enlargement










Radiographic Findings of Pulmonary Congestion and Edema










Echocardiography


• Echocardiographic examination of patients with MVD demonstrates variable degrees of left atrial (Figure 6-7) and left ventricular dilation. Hypertrophy is usually adequate to preserve a near-normal relationship between the diastolic luminal dimension and wall thickness.









• Doppler evidence of disturbed flow within the left atrium during systole is noninvasive confirmation of the presence of MR (see Figure 6-8). When stroke volume is severely affected by MR or systolic failure, reductions in aortic outflow velocities may be apparent.





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Aug 15, 2016 | Posted by in SMALL ANIMAL | Comments Off on Acquired Valvular Disease

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