Some types of valvular heart disease include valvular stenosis, vascular prolapse and regurgitation. Mitral stenosis is uncommon and not as age-dependent as other types of valvular disease. Patients have developed hypertrophic cardiomyopathy, arrhythmias, conduction abnormalities, and valvular abnormalities. Serious side effects may include pulmonary hypertension, valvular heart disease, and abuse. Recurrent bouts of rheumatic fever can lead to valvular heart disease. About half of patients with rheumatic fever develop inflammation involving valvular endothelium. Several studies have also implicated warfarin use in valvular and vascular calcification. This enables detailed anatomical assessment of cardiac pathology, particularly valvular defects, and cardiomyopathies. It is almost always caused by rheumatic valvular heart disease. Jenner contributed papers on angina pectoris, ophthalmia, and cardiac valvular disease and commented on cowpox. An echocardiograph may be used to further assess for valvular lesions. Turbulent flow causes dephasing and signal loss allowing valvular disease to be qualitatively appreciated. MR is the most common form of valvular heart disease. Patients may also have a history of poor dental hygiene, or pre-existing valvular disease. It is one of the two most common valvular heart diseases in the elderly.