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Nitric oxide inhalation in the treatment of right ventricular dysfunction following left ventricular assist device
Background:
Following left ventricular assist device (LVAD) implantation in end-stage heart failure, the management of right ventricular dysfunction presents a therapeutic problem unresolved by conventional drug therapy (catecholamines, nitrates, and prostacyclin). This study was performed to investigate the effects of supplemental inhalation of nitric oxide (NO), a selective pulmonary vasodilator, postoperatively and prospectively.
Methods And Results:
Intraindividual dose titration of NO was performed (0 to 40 ppm) according to a standardized protocol. Thereafter treatment was continued with the individually most effective dose of NO (25 to 40 ppm). In 8 consecutive male patients presenting with right ventricular dysfunction postoperatively, a significant dose-dependent improvement in hemodynamic function was observed: pulmonary vascular resistance decreased from 336+/-110 to 210+/-59 dynes x s x cm(-5) (P<.0001), cardiac index rose from 2.0+/-0.4 to 2.7+/-0.4 L x min(-1) x m(-2) (P<.003) at 40 ppm; doses of >20 ppm were effective in increasing cardiac index (P<.05). With continuous NO inhalation up to 48 hours, pulmonary vascular resistance decreased further to 155+/-33 dynes x s x cm(-5) (P<.0001) as the cardiac index increased to 3.3+/-0.6 L x min(-1) x m(-2) (P<.003). Pulmonary artery pressure decreased (P<.0001) as did systemic vascular resistance with hemodynamic improvement (P<.01). Central venous pressure and mean arterial pressure remained unchanged. Right ventricular ejection fraction at transesophageal echocardiography increased from 24+/-7% to 44+/-7% (P<.01) at the end of the study, and right ventricular end-diastolic volume decreased (P<.05). Weaning from NO therapy was successful at 2 to 8 days, and all patients were extubated. Right ventricular function remained stable thereafter.
Conclusions:
In the treatment of right ventricular dysfunction following LVAD implantation, inhalation of NO markedly decreased right ventricular afterload by its selective vasodilating effects on the pulmonary circulation without producing systemic hypotension; this merits further evaluation.