Coronary and forearm blood flow reserve in essential hypertension

Impaired forearm vasodilator reserve as a consequence of the structural adaptation of systemic resistance-sized arterioles in response to elevated blood pressure (BP) is considered as a hallmark of human arterial hypertension. Whether this abnormality goes in parallel with comparable alterations of coronary perfusion reserve (CPR) in essential hypertensive patients (EH) is unknown. : Myocardial blood flow (MBF, ml/min/g by N-13 ammonia and positron emission tomography) at rest and after i.v. dipyridamole (0.86 mg/kg over 10 minutes), CPR (maximum/baseline MBF) and minima] forearm vascular resistances (Rmin, arbitrary units, mean arterial pressure/plethysmographic forearm blood flow during hyperemia following 13-minutes forearm occiusion) were measured off-therapy in 23 mild-moderate uncomplicated male EH (age: 58.+5yrs, BP: mmHg). 7 sex-, age-matched (57.7±4 yrs) normotensives (BP: mmHg) were the controls (C). (means±SEM): Rmin were greater in EH than C 2.7±.16 vs 2.0±.16, p<.02) without correlation with individual CPR values (r=.02, p:NS). In a subgroup analysis, Rmin values were 2SD above C in 9 EH (3.42±.23, High Rmin) and in the normal range (2.26±0.8, Normai Rmin) in the remaining 14. After DIP, MBF increased from .83±.07 to 1.98±.15, and from .8±.04 to 2.1±.24 in the High and Normal Rmin group respectively; therefore, CPR was comparable (2.5±26 vs 2.7±.32 respectively). The correlation between Rmin and CPR was absent in both subgroups (r=.05 and R=.07, Normal and High Rmin respectively). Coronary and forearm vasodilator reserve are unrelated parameters in EH.