Valvular heart disease - pathophysiology and management

Valvular heart disease (VHD) is common and it is essential that hospital pharmacists understand the disease and the role of pharmacotherapy in its treatment and prevention. The heart is composed of four chambers (two atria and two ventricles) and contains four valves (mitral and aortic valves on the left, tricuspid and pulmonary valves on the right). The valves prevent blood flowing backwards within the systemic (left side) and pulmonary (right side) circulations (see Figure 1, p120). Many disease processes affect the cardiac valves.Disease may cause valve stenosis (narrowing) or regurgitation (blood leaking in the wrong direction), with haemodynamic consequences. Acute or subacute infection, most commonly bacterial endocarditis, can destroy heart valves, as can connective tissue diseases. Diseases of the chambers can also affect the valves and cause functional disease. Thirty years ago, the most common cause of VHD in people under the age of 60 years was rheumatic heart disease — an immunological reaction to streptococcal infection. Widespread antibiotic use has reduced the incidence of rheumatic heart disease, and the most common form of VHD is now degenerative valvular disease in elderly patients. Comorbidity is common; atherosclerosis, renal impairment and chronic obstructive pulmonary disease are the most frequent conditions found in VHD patients. Increasing numbers of patients are now undergoing valve replacement operations, and optimising cardiac function in patients awaiting these operations has become an important aspect of patient care. Following surgery, there is a strong emphasis on anticoagulation monitoring and antibiotic prophylaxis against endocarditis. This article will describe how the six most common forms of VHD are managed. A second article (p127) focuses on anticoagulation and prophylaxis of endocarditis.