Hazards ofdiazoxide inpulmonary hypertension

SUMMARY Theuseofdiazoxide inthetreatment ofpulmonary hypertension hasbeenadvocated recently. We describe three patients whoresponded less favourably. Thefirst patient hadcardiac arrest (asystole) after theacutebolus dose. After recovery only aslight increase incardiac index was seenwhilepulmonary vascular resistance was unchanged. Thesecondpatient developed total atrioventricular blockafter theacutebolus dose. After recovery thecardiac index was unchanged while pulmonary vascular resistance was decreased. Thethird patient felt ill after theacutebolus dose, andtheblood pressuredropped, butno conduction abnormalities werenoted. Thecardiac index roseslightly andthepulmonary vascular resistance was essentially unchanged. Longterm treatment withoral diazoxide could notbeadministered tothis patient because abdominal pain and distension developed. Because we lackreliable alternative treatment, itisjustifiable totrydiazoxide, provided great careistaken. Vasoconstriction ofthepulmonary vascular system plays animportant roleinthepathogenesis of pulmonary hypertension. Accordingly various vasodilators havebeentried inthetreatment butthe results haveingeneral beenunsatisfactory.' Recently, diazoxide hasbeenshowntohavea promising effect2 3andfurther evaluation wasfelt to bewarranted. Wereport here thehazards andserious side effects intheuseofdiazoxide inthree patients withprimary pulmonary hypertension. Patients CASE 1 A 32-year-old womanhaddeveloped symptoms ofa collagen disease twoyears earlier, which wasclassified asamixed connective tissue disease withmanifestations ofbothsystemic lupus erythematosus and scleroderma. Shethendeveloped exertional dyspnoea andhadrecurrent attacks ofpneumonia andpleurisy. Shewastreated initially withpenicillamine andlater withlarge doses ofprednisone, withsomesymptomaticrelief. Shewasadmitted after increasing dyspnoea onexertion forsixmonths, andfound tobe dyspnoeic andmildly cyanosed atrest. Therewere signs ofright sided heart failure consisting ofengorgementoftheneckveins, liver enlargement, ascites, andperipheral oedema. Pulmonary function tests disclosed a severely impaired diffusion capacity.