Balloon Atrial Septostomy for Primary Pulmonary Hypertension
October 1, 1998 3 minutes read
Balloon Atrial Septostomy for Primary Pulmonary Hypertension
ABSTRACT & COMMENTARY
Synopsis: Balloon atrial septostomy is safe and useful for selected patients with severe PPH.
Source: Sandoval J, et al. J Am Coll Cardiol 1998; 32:297-304.
Current medical therapy of primary pulmonary hypertension (PPH) involves anticoagulation and calcium channel blocking drugs. Long-term benefit from vasodilator therapy is £ 30%. Often, more aggressive therapies, such as continuous infusion of prostacyclin and lung transplant, are limited by reduced resources. Blade-balloon atrial septostomy can result in significant clinical improvement but has a high reported mortality. Thus, this favorable report of the results of graded balloon atrial septostomy for PPH is of interest. Sandoval and associates performed 22 balloon septostomy procedures in 15 patients aged 22-51 years with severe PPH. The balloon is brought across the interatrial septum by the transseptal puncture technique, and the mansfield balloon progressively inflated from 8-16 mm in diameter. Successful balloon septostomy was achieved when systemic oxygen saturation was above 75% and the left ventricular end-diastolic pressure was less than 18 mmHg. After the procedure, anticoagulation and nocturnal supplemental oxygen were used during the 2-36 months follow-up. Balloon septostomy resulted in an immediate decrease in right heart pressures and systemic oxygen saturation from 92% to 83% (P < 0.05). Cardiac index increased from 2.2 to 3.0 l/min/m2 (P < 0.05), and exercise endurance increased 110 m on the 6 minute walk test (P < 0.0.01). One patient did not survive the procedure, and four patients developed spontaneous closure. Long-term survival was 92% for up to three years, which is better than the historical control PPH patients of 52% or the NIH PPH registry data prediction formula of 38%. Sandoval et al conclude that balloon atrial septostomy is safe and useful for selected patients with severe PPH.
COMMENT BY MICHAEL H. CRAWFORD, MD
PPH is a difficult clinical problem-especially if the patient does not respond to vasodilator therapy-because the majority do not. The lack of availability and cost of continuous intravenous prostacyclin or lung transplantation prohibits their use in many patients. Thus, the observation that PPH patients with a patent foreman ovale and Eisenmenger patients had improved survival as compared to PPH patients without a shunt stimulated interest in percutaneous atrial septostomy as a palliative treatment for PPH patients unresponsive to vasodilators. Theoretically, the creation of an atrial defect allows for right to left shunting at the atrial level, which decompresses the right ventricle and increases left ventricular volume and output. The increased left ventricular output should increase oxygen delivery despite the reduced oxygen saturation. The latter eventually results in increased hemoglobin content, which also aids oxygen delivery.
The concept works only if pulmonary blood flow increases or remains nearly the same, so that oxygen saturation does not fall too low. Patients with severe pulmonary hypertension or right ventricular failure had a high mortality rate with early blade septostomy procedures because the suddenly large shunt could not be accommodated. Presumably, this would be the case with balloon septostomy as well. The only death in this series was in a patient with severe right ventricular failure.
The advantage of balloon septostomy is the ability to progressively enlarge the opening while monitoring hemodynamics. The disadvantage is the 20% incidence of spontaneous closure. However, this was easily treated with repeat procedures. The main limitation of this study is that the controls are historical and registry derived formulas. Also, better patient selection today could make blade septostomy safer than reported. Of interest, the PPH patients in this study had mean pulmonary artery pressures of approximately 60 mmHg, all were New York Heart Association class III or IV, and all had right ventricular end-diastolic pressures of about 16 mmHg. Thus, this was hardly a low severity population. In this context, the results are impressive and suggest that this procedure should be more widely used.
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