Figure 1.

Sympathetic nervous system activation is increased in pulmonary arterial hypertension (PAH). (A) Muscle sympathetic nerve activity neurograms demonstrate increased sympathetic nerve traffic in skeletal muscle of PAH patients compared to controls. (B) This correlates with more severe heart failure symptoms as assessed by the New York Heart Association (NYHA) functional class. (C) Cardiac imaging with ¹²³I- metaiodobenzylguanidine (MIBG), a norepinephrine analog that competes with norepinephrine for uptake, showing a reduction in ¹²³I-MIBG uptake (i.e., higher norepinephrine uptake) in the RV of a patient with severe pulmonary hypertension. HR, heart rate; BP, blood pressure; s, seconds, PH, pulmonary hypertension. Reproduced with permission from references 21, 22.