Hypertension 1996 : One Medicine, Two Cultures
Hypertension and peripheral arterial disease
V. Vagni
Department of Vascular Surgery, G.B. Grassi Hospital, Italy
The clinical predominance of peripheral arterial disease (PAOD) is comprised between 1-1.5% below the age of 50 years and 5% above 50 years of age, moreover instrumental predominance is significantly larger (6,19). The incidence is 4% in the age included between 34 and 44 years, and 18% above 65 years of age. However only one third of the patients presents the symptom of claudicatio. In women PAOD manifests about 10 years later than men. Man/women ratio is slightly inferior to 2, but if we consider patients with critical ischaemia, the ratio changes, according to the record of cases, from 3 to 13(1,8, 17, and 18). In patients with The arterial disease, mortality is two-three times superior than a homogeneous group of general population (2,5, 12). In PAOD pathogenesis, we distinguish MAJOR and MINOR risk factors. Major risk factors include:
LIPOIDOPROTINOSIS (Hypercholesterolaemia, hypertriglyceremia)(10,1 5).
DIABETES which is associated to atheroscierosis, in a percentage included between 5.4 and 2l.2 (7,l1). Diabetics show a high incidence of PAOD of lower limbs, with the prevalent involvement of tibial area, as compared to other arteriopathics. Diabetes is present in 11% of patients with PAOD of lower limbs as against 0.9% of the defined population. (10).
SMOKE increases nine times the atherosclerotic lesions onset, and furthermore it accelerates their progression.
HYPERTENSION is present in one third of the patients with PAOD, as compared to the 82 of non-arteriopathic patients. In a recent research, Binaghi et al., have shown that the predominance of hypertension in patients with PAOD is 21.6%, second only to hypercholesterolaemia (59.1%) (3). Hypertension is related to the risk of premature atherosclerosis risk, independently from other major risk factors (hypercholesterolaemia and smoke). Hypertension increases the tendency of lesions to localize, more frequently, at the fork of inferior limbs arteries' origin, being these points, those where normally pressor insult is higher. To confirm the importance of hypertension, it is good to remember the rarity, even in presence of serious systemic lesions, of atherosclerotic lesions of the pulmonary circulation, where a low-pressure status is present, and how these will manifest with the onset of pulmonal hypertension. MINOR risk factors, especially in industrialised countries comprehend hypercolorific, obesity and sedentary. Therapeutic aim in hypertensives with PAOD is to correct the hypertension, since this influences negatively the atherosclerosis. It's however necessary to consider the particular end emodinamic situations of hypertensive with PAOD. The excess reduction of blood pressure can be harmful for the claudicatio, as it leads to the reduction of peripheral perfusion. Roberts has noticed how some antihypertensive drugs, and particularly B-blockers, affect negatively on the walking endurance of limping subjects with PAOD, while categories of drugs, as ACE-inhibitor do not influence this parameter. On the other hand, a study conducted by Heintzen et al. has demonstrated that in non severe forms of PAOD, the B-blockers have had little effect on tries peripheral circulation and, on the contrary can better the flow in the ischaemic areas on the basis of an inverse steal effect (9). While it is notorious that high-pressure regimes lead to an increased incidence of atherosclerosis, and to its faster evolution, it is not yet clear the correction of such parameter, might somehow modify the natural history of the disease itself. The gold standard of medical therapy in PAOD, of inferior limbs in hypertensive, is to have an antihypertensor drug, that can possibly carry out effect;: that promote tissular perfusion, particularly, dilating vessels and increasing the flow in the ischaemic area, mainly during locomotion, as the increased muscular activity requires a higher contribution of oxygen. At the moment it doesn't exist a drug having these characteristic even if Ca-antagonist have an antivasoconstrictor and antiaggregrant, reducing Ca concentration in un-striated muscular cells, and reducing the number of platelets that perform their action on both cutaneous and muscular vessels. Among Ca-antagonist flunarizine is the one that acts in a selective way on un-striated musculature of the vessels, with a significant increase of the autonomy and of free time of walking. In association with the medical therapy, it is possible in PAOD, to use methods and technologies, to restore the vessels' patency (PTA- PTA laser) And to increase the flow in the isechaemic area through blocking the simpatico (peridural block, medulla’s electric stimulation).in all those cases in which the surgical operation of direct is inadvisable. In the hypertensive therapy, with PAOD, physical activity is complementary, but not less important, being a primary factor. In fact, it has been demonstrated, that physical activity reduces the frequency of cardiovascular diseases (14), but it is not known if this beneficial effect depends on a antihypertensive answer to the physical activity The absence of physical exercise is associated to a major incidence of hypertension (4), but if regularly done, it reduces both the systolic and the diastolic pressure, of about 10 mmHg (13) through reducing the catecholamines and the increase of the atrial natriuretic factor (ANF). Surgical Therapy of peripheral arterial disease includes a direct revascularization, by pass, or an indirect one (sympathicotomia or arteria profunda revascularization). Often in the natural course of the history of PAOD, arrives the moment when the vital perfusion of a limb, cannot be maintained without the installation of a vascular prothesis, whose good functioning depends also on a continuos and cautious pharmacological treatment
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Edited by Aldo Campana,