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Decreased regional blood flow in patients with acromegaly
P Chanson1, J L Megnien, M del Pino
1Service d'Endocrinologie et des Maladies de la Reproduction, Centre Hospitalier Universitaire de Bicêtre. pchanson@club-internet.fr
Insights
In acromegaly patients with hyperkinetic heart syndrome, regional blood flow in the brachial artery is paradoxically lower, and vascular resistance is higher, despite increased cardiac output. This suggests uneven blood flow distribution in acromegaly.
Area of Science:
- Cardiology
- Endocrinology
- Vascular Physiology
Background:
- Acromegaly is linked to hypertension and a hyperkinetic heart syndrome, characterized by increased cardiac output and decreased systemic vascular resistance.
- This suggests augmented blood flow in regional vascular beds of acromegalic patients.
Purpose of the Study:
- To directly measure brachial artery blood flow and vascular resistance in acromegalic patients with confirmed hyperkinetic heart syndrome.
- To compare these measurements with those of healthy controls.
Main Methods:
- Twelve acromegalic patients and twelve age- and sex-matched controls were studied.
- Right heart catheterization assessed cardiac index and systemic vascular resistance.
- A two-dimensional pulsed Doppler system evaluated brachial artery haemodynamics, including diameter, mean blood velocity, and calculated mean blood flow.
- Brachial artery vascular resistance was computed as the ratio of mean arterial pressure to blood flow.
Main Results:
- Acromegalic patients exhibited higher mean arterial pressure, increased cardiac index, and low systemic vascular resistance compared to controls.
- Despite similar brachial artery diameter, patients showed lower mean blood velocity and mean blood flow in the brachial artery.
- Forearm vascular resistance was significantly higher in acromegalic patients than in controls.
Conclusions:
- Active acromegaly is associated with increased cardiac output and decreased systemic vascular resistance.
- However, direct brachial artery measurements reveal reduced regional blood flow and elevated local resistance.
- These findings indicate a heterogeneous distribution of cardiac output in acromegaly.
Background And Aims:
One-third of acromegalic patients have hypertension. Acromegaly is also associated with intrinsic cardiac abnormalities known collectively as a hyperkinetic heart syndrome, which is characterized by an increased cardiac index and decreased systemic vascular resistance. As a result, blood flow should be increased in the regional vascular beds of acromegalic patients. The aim of the study was to measure, using direct methods, blood flow and vascular resistance at the level of the brachial artery in acromegalic 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 and stroke volume and to calculate systemic vascular resistance in the acromegalic patients. Brachial haemodynamics were evaluated with a two-dimensional pulsed Doppler system (double transducer probe and range-gated time system of reception). The mean diameter of the brachial artery and mean blood velocity were measured and used to calculate mean blood flow. Vascular resistance was calculated in the brachial artery as the mean arterial pressure/blood flow ratio.
Results:
Age, body weight, height, body surface area and heart rate were similar 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/m2 body surface area and 116.7 +/- 19.4 ml, 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 controls (3.35 +/- 1.26 vs. 5.12 +/- 1.74 cm/s, and 16.4 +/- 9.4 vs. 25.6 +/- 11.6 ml/min/m2, respectively). The higher mean arterial pressure and lower mean blood flow resulted in higher forearm vascular resistance in the patients than in the controls (132 +/- 61 vs. 83.8 +/- 47 mmHg/ml/s/m2, respectively, P < 0.01).
Conclusion:
While cardiac output is increased and systemic vascular resistance is decreased in active acromegaly, direct measurement of brachial artery haemodynamics showed lower regional blood flow and increased local resistance relative to healthy controls. These results suggest a heterogeneous distribution of cardiac output in acromegaly.