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Pulmonary hypertension.

Progress in the diagnosis and treatment of pulmonary arterial hypertension has expanded options for patients. The American College of Chest Physicians recently published an evidenced-based set of guidelines for this difficult condition.

Background

Pulmonary arterial hypertension (PAH) does not become symptomatic until the vascular disease is advanced. Thus, even mild elevations in arterial pressure reflect extensive disease.

Dyspnea may be present at rest. Exertional dyspnea is the most frequent presenting symptom, but fatigue, weakness, or complaints of exertional intolerance are also common presenting complaints.

Nearly 40% of patients suffer angina or syncope during the course of their disease.

Physical examination signs are subtle. More than 90% of patients have an accentuated pulmonic component of the second heart sound. Advanced disease frequently features the murmur of tricuspid regurgitation.

The ECG can show right ventricular hypertrophy and right-axis deviation. Prominent R-waves in the anterior chest leads provide additional clues.

Pulmonary hypertension can be seen in connective tissue disease but is most frequent in systemic sclerosis. Although interstitial fibrosis may result in pulmonary hypertension, patients with scleroderma and severe hypertension often have little parenchymal involvement.

Prostacyclin is a potent vasodilator produced in the vascular endothelium. Studies appear to indicate a relative deficiency of prostacyclin in patients with PAH.

Modulation of cyclic guanine monophosphate (cGMP) content in vascular smooth muscle plays a critical role in pulmonary hypertension. Nitrous oxide has vasodilator effects because of its ability to create a sustained increase of cGMP. Inhibition of phosphodiesterase, which degrades cGMP, holds promise as a therapeutic option.

Implementation

* Patients suspected of having PAH should undergo Doppler echocardiography as a noninvasive screening test. Although it can detect pulmonary hypertension, it is imprecise in determining arterial pressures.

* Patients with suspected pulmonary hypertension should undergo confirmatory right heart catheterization. This excludes other causes such as intracardiac or extracardiac shunts or left-sided heart disease.

* Patients with confirmed PAH should undergo serial assessments by a 6-minute walk test to provide benchmarks for disease severity, progression, and response to therapy.

* Patients should undergo ventilation perfusion scanning to rule out chronic thromboembolic pulmonary hypertension. A normal scan precludes this diagnosis. Contrast-enhanced CT or MRI should not be used to diagnose chronic thromboembolic disease. Pulmonary angiography remains the diagnostic procedure of choice in selected patients for accurate diagnosis and best anatomic definition to determine operability of the condition. Pulmonary thromboendarterectomy may provide a surgical cure for patients who suffer from chronic thromboembolic disease.

* Pregnancy should be avoided and termination should be recommended in patients with PAH.

* Patients with a confirmed diagnosis should have vasoreactivity testing to identify those who are responsive to oral calcium channel blockers. Such testing usually involves intravenous epoprostenol or inhaled nitrous oxide.

* Despite the recommendation for this treatment, there have not been substantial reports of success or randomized clinical trials of calcium channel blockers in the treatment of PAH. If used, agents with negative inotropic effects, such as verapamil, should be avoided.

* Microscopic thrombosis has been documented in some patients with pulmonary hypertension. Reports of improved survival with oral anticoagulation have prompted many experts to use warfarin.

* Patients with New York Heart Association class IV functional status who are not candidates for or have failed calcium channel blocker therapy should be considered for long-term therapy with the intravenous prostanoid epoprostenol. Such prostacyclin therapy requires a long-term indwelling catheter and an infusion pump. Such patients should be managed by clinicians with specific experience.

* Sildenafil blocks acute hypoxic pulmonary vasoconstriction in healthy volunteers and reduces mean pulmonary pressure in patients with pulmonary arterial hypertension. Early reports show promising results regarding therapeutic efficacy in the long-term management of chronic PAH. It should be considered in patients who have failed or are not candidates for other therapies.

* Patients unresponsive to medical therapy could be considered for atrial septostomy, which creates a right to left shunt and thus decompresses the right ventricle and increases left ventricular preload. Other patients should be considered for lung or heart-lung transplantation.

Reference

Diagnosis and management of pulmonary arterial hypertension: ACCP evidence-based clinic practice guidelines (Chest 126[1 Suppl.] 1S-92S, 2004). www.chestnet.org/guidelines.

BY WILLIAM E. GOLDEN, M.D., AND ROBERT H. HOPKINS, M.D.

DR. WILLIAM E. GOLDEN is professor of medicine and public health and DR. ROBERT H. HOPKINS is associate director of the medicine/pediatrics residency program at the University of Arkansas, Little Rock. Write to Dr. Hopkins and Dr. Golden at our editorial offices or imnews@elsevier.com.
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Title Annotation:The Effective Physician
Author:Golden, William E.; Hopkins, Robert H.
Publication:Internal Medicine News
Geographic Code:1USA
Date:Sep 1, 2004
Words:734
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