Abstract

ARMENTANO, RICARDO et al. Disipación energética y protección vascular durante la hipertensión arterial sistémica: rol del músculo liso. Rev.Urug.Cardiol. [online]. 2005, vol.20, n.3, pp.125-135. ISSN 1688-0420.

SUMMARY Introduction: arteries smooth out the high frequency components of the pressure and flow waves, dissipating energy. The arterial buffering protects the vascular wall from potential damages related to those high frequency components. Objective: to analyse the role of the vascular smooth muscle (VSM) in the protective effect against high frequency oscillations and in the energy dissipation, of human carotid arteries (CCA) from normotensive subjects, hypertensive patients without treatment, and hypertensive treated with angiotensin converting enzyme (ACE) inhibitors. Methods: noninvasive CCA pressure (tonometry) and diameter (echography) waveforms were measured in normotensive subjects (n=12) and in hypertensive patients (n=22) randomized into placebo (n=10) or ACE inhibitors (ramipril, 5-10 mg/day during 3 months, n=12). In vitro, pressure and diameter were registered in CCAs (n=14, null tonus) obtained from donors and submitted to haemodynamic conditions similar to those of the in vivo studies. Using adaptative modelling, we calculated, for each beat, the viscous, elastic and inertial indexes; the dissipated viscous energy (W_h) and the wall protection. Results: in hypertensive patients, W_h was higher (p<0,05) than in normotensive subjects, while the wall protection remained unchanged. Only in the treated hypertensives, W_h was reduced and it was near to the normotensive values, without changes in the wall protection. During the null tonus condition, both, W_h  and the wall protection were lower than in the the normotensive subjects (p<0,01). This showed the dependence of those parameters on the VSM tone. Conclusion: the arterial system keeps the vascular wall protection. The VSM protects the vascular wall, dissipating energy. During hypertension the energy dissipation increases, and the buffering and wall protection is preserved. The energy dissipation can be reduced (treatment), reducing the ventricular charge, at the time the wall protection is kept unchanged.

Keywords : ARTERIES; MUSCLE,SMOOTH, VASCULAR; HYPERTENSION; BLOOD PRESSURE.

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