Decreased regional blood flow in patients with acromegaly

BACKGROUND AND AIMS One-third of acromegalic patients have hypertension. Ac romegaly is also associated with intrinsic cardiac abnormalities known coll ectively as a hyperkinetic heart syndrome, which is characterized by an inc reased cardiac index and decreased systemic vascular resistance. As a resul t, blood flow should be increased in the regional vascular beds of acromega lic patients. The aim of the study was to measure, using direct methods, bl ood flow and vascular resistance at the level of the brachial artery in acr omegalic patients with a confirmed hyperkinetic heart syndrome. PATIENTS AND CONTROLS Twelve patients with active acromegaly (five females, seven males; mean (+/- SD) age, 43 +/- 10 years) were studied. Twelve age- and sex-matched normal subjects served as controls. METHODS Right heart catheterization was used to measure the cardiac index a nd stroke volume and to calculate systemic vascular resistance in the acrom egalic patients. Brachial haemodynamics were evaluated with a two-dimension al pulsed Doppler system (double transducer probe and range-gated time syst em of reception). The mean diameter of the brachial artery and mean blood v elocity were measured and used to calculate mean blood flow. Vascular resis tance was calculated in the brachial artery as the mean arterial pressure/b lood flow ratio. RESULTS Age, body weight, height, body surface area and heart rate were sim ilar in the acromegalic patients and controls, while mean arterial pressure was higher in patients. The cardiac index and stroke volume were increased in the acromegalic patients, at 4.08 +/- 0.47 (mean +/- SD) l/min/m(2) bod y surface area and 116.7 +/- 19.4 mi, respectively, while systemic vascular resistance was low (12.5 +/- 2.1 U). Brachial artery diameter was similar in the patients and controls. Brachial artery mean blood velocity (P < 0.01 ) and mean blood flow (P < 0.05) were lower in the patients than in the con trols (3.35 +/- 1.26 vs. 5.12 +/- 1.74 cm/s, and 16.4 +/- 9.4 vs. 25.6 +/- 11.6 ml/min/m(2), respectively). The higher mean arterial pressure and lowe r mean blood flow resulted in higher forearm vascular resistance in the pat ients than in the controls (132 +/- 61 vs. 83.8 +/- 47 mmHg/ml/s/m(2), resp ectively, P < 0.01). CONCLUSION While cardiac output is increased and systemic vascular resistan ce is decreased in active acromegaly, direct measurement of brachial artery haemodynamics showed lower regional blood flow and increased local resista nce relative to healthy controls. These results suggest a heterogeneous dis tribution of cardiac output in acromegaly.