Analysis of Arterial Function in Arterial Hypertension

pp 433-438

Abstract

Background

Non invasive methods are currently able to detect simply and adequately arterial rigidity. Their use in patients with borderline hypertension may lead to better understanding of mechanisms involved in the alteration of the arterial wall.

Method

To evaluate the usefulness of non invasive arterial impedance measurement as an efficient and early marker of vascular damage in borderline and essential hypertensives, ten normotensive (NT),10borderline hypertensives (BDL) and 10 essential hipertensives (HT) were studied. Each subject was submitted to the following measurements: mean arterial pressure (MAP)by sphygmomanometry (Dinamap Critikon), mean humeralarterial diameter (MD) by high resolution echography (Hewlett Packard, Sono 1500) and mean blood flow (MF) by strain gauge plethysmographyc. Pulse wave velocity(PWV) was calculated from simultaneous carotid and femoral arterial pressure recordings with two strain gauge mechanographic transducers positioned simultaneously at the level of carotid andfemoral arteries. Total arterial compliance (C) was calculated from a formula derived of the Bramwell-Hill equation. Peripheral resistance was defined as PR= MAP/MF and characteristic resistance asRC= aPWV/hr4. MD2, whereais the blood density, and reflection coefficient (F) =(Rc-PR/Rc=PR). We calculated the mismatch index (MI) as:PWV-F. The difference between those parameters was evaluated using the student "t" test with Bonferroni correction.

Results

Mean arterial pressure was increased in borderline hypertensives (95 ± 7 mmHg; p<0.002) and essential hypertensives (124 ±9 mmHg; p < 0.0001) with respect to normotensives (79 ± 11 mmHg). Mean blood flow was increased in borderline hypertensives (4.1 ±1.5 cm3/sec; p<0.0001) and hypertensives (4.7 ± 1.6 cm3/sec; p < 0.0001) with respect to normotensives (17.6 ± 3.8 cm3/sec) 

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Conclusions

Sustained and borderline hypertension were accompanied by alterations in arterial impedance parameters. The information obtained from this analysis gave a global knowledge of state of the circulatory system, that can be used to evaluate the arterial alterations induced by hypertension. These alterations could be explained by an increase in magnitude and early arrival of the reflected wave. The hemodynamic alterations might affect left ventricular ejection by increasing cardiac after load and decreasing coronary perfussion pressure. In conclusion, hypertension can develop early structural and functional changes in the cardiovascular system. The earliest detection of these alterations may reduce the negative impact over the heart.