Diagnosis of pulmonary hypertension.

Pulmonary hypertension may complicate a variety of congenital or acquired cardiac and pulmonary conditions. This vascular disorder results from conditions that lead to a chronic increase in left atrial pressure, increased pulmonary blood flow, or increased pulmonary vascular resistance. Definitive diagnosis requires cardiac catheterization and detection of systolic and mean pulmonary artery pressures exceeding 30 and 20 mm Hg, respectively. Clinical signs and historical complaints reflect underlying cardiac or pulmonary conditions, although syncope may be a predominant finding. Radiographic changes are nonspecific; however, right ventricular enlargement and enlarged pulmonary arteries should increase suspicion for the disorder. Estimates of pulmonary arterial pressure may be obtained through Doppler echocardiography. This requires detection of a high-velocity regurgitant jet across the tricuspid or pulmonic valve. Further investigation is required to determine how pulmonary hypertension impacts therapy and prognosis for dogs and cats with cardiac and pulmonary diseases.