The assessment and treatment of hypertension. New views on essential hypertention

Effect of Accessory Renal Arteries on Essential Hypertension and Related Mechanisms

BACKGROUND

This case-control study aimed to determine whether there were differences between patients with essential hypertension with accessory renal arteries (ARAs) and those without ARAs.

METHODS AND RESULTS

The enrolled patients with essential hypertension were divided into the ARA group (n=200) and control group without ARAs (n=238). After propensity matching, 394 patients (197 in each of the 2 groups), were included. The 24-hour BP (4.33/2.43 mm Hg) and daytime BP (4.48/2.61 mm Hg) of patients in the ARA group were significantly higher than those of the control group (P<0.05). The flow-mediated dilation was lower in the ARA group (5.98±2.70 versus 5.18±2.66; P<0.05). In correlation analysis, the horizontal plasma aldosterone concentration had the highest correlation with 24-hour, daytime, and nighttime systolic BP (r=0.263, 0.247, and 0.243, respectively; P<0.05) and diastolic BP (r=0.325, 0.298, and 0.317, respectively; P<0.05). As for multivariate regression analysis, plasma aldosterone concentration was a significant risk factor for elevated 24-hour, daytime, and nighttime systolic BP (β=0.249 [95% CI, 0.150-0.349], 0.228 [95% CI, 0.128-0.329], and 0.282 [95% CI, 0.187-0.377], respectively; P<0.05) and elevated diastolic BP (β=0.289 [95% CI, 0.192-0.385], 0.256 [95% CI, 0.158-0.353], and 0.335 [95% CI, 0.243-0.427], respectively; P<0.05). Direct renin concentration was also a risk factor for 24-hour and daytime BPs, whereas heart rate was a risk factor correlated with 24-hour, daytime, and nighttime diastolic BP (all P<0.05). For the mixed-effects model for repeated measures, the results were similar to results of the multivariate regression analysis (all P<0.05).

CONCLUSIONS

ARAs could contribute a higher BP of patients with essential hypertension and might promote the development of essential hypertension. The mechanism might be related to overactivation of the renin-angiotensin-aldosterone system and sympathetic nervous system.

Accessory or additional renal arteries show no relevant effects on the width of the upper urinary tract: a 64-slice multidetector CT study in 1072 patients with 2132 kidneys

OBJECTIVE

The aim of this study was to find out on an unselected patient group whether crossing vessels have an influence on the width of the renal pelvis and what independent predictors of these target variables exist.

METHODS

In this cross-sectional study, 1072 patients with arterially contrasted CT scans were included. The 2132 kidneys were supplied by 2736 arteries.

RESULTS

On the right side, there were 293 additional and accessory arteries in 286 patients, and on the left side there were 304 in 271 patients. 154 renal pelves were more than 15 mm wide. The greatest independent factor for hydronephrosis on one side was hydronephrosis on the contralateral side (p<0.0001 each). Independent predictors for the width of the renal pelvis on the right side were the width of the renal pelvis on the left, female gender, increasing age and height; for the left side, predictors were the width of the renal pelvis on the right, concrements, parapelvic cysts and great rotation of the upper pole of the kidney to dorsal. Crossing vessels had no influence on the development of hydronephrosis. Only anterior crossing vessels on the right side are associated with widening of the renal pelvis by 1 mm, without making it possible to identify the vessel as an independent factor in multivariate regression models.

CONCLUSION

The width of the renal pelvis on the contralateral side is the strongest independent predictor for hydronephrosis and the width of the renal pelvis. There is no link between crossing vessels and the width of the renal pelvis.

A possible explanation for the frequent concomitance of arterial hypertension and multiple renal arteries

In more than 20% of subjects, at least one kidney is found to be supplied by more than one artery arising from the aorta. This aberrant renovascular anatomy has been reported in the literature to occur in up to 80% of patients who suffer from essential hypertension. Predominant numbers of the so-called 'accessory' vessels are longer and narrower than the segmental arteries arising in the main renal artery. As a result (in accordance with Poiseuille's law of fluid flow), the renal segments supplied by these 'accessory' vessels may have lower levels of blood pressure than the remainder of the parenchyma, thereby increasing the renin secretion. This hypothesis could be significant in terms of finding a causal treatment for a disorder induced by such a mechanism. We first review the literature in which the frequency of these vascular anomalies in normotensive and hypertensive patients is described, and then advance a hypothesis explaining the frequent incidence of essential hypertension in these subjects, as well as the ramifications of this phenomenon.

Hypertension associated with multiple renal arteries may be renin-dependent

OBJECTIVE

Subjects with multiple renal arteries have been shown to suffer more frequently from hypertension and to have higher blood pressures than subjects whose kidneys are supplied by single renal arteries. This study was carried out to determine whether subjects with multiple renal arteries also have higher renin activity.

METHODS

We studied 62 consecutive patients who had undergone angiography for various reasons. They were divided into two groups. Group A comprised 29 patients whose kidneys were supplied by single arteries (male :female ratio 1.63, mean age 51.8 +/- 1.9 years) while Group B comprised 33 patients with multiple renal arteries (male:female ratio 2, mean age 47.3 +/- 2.3 years).

RESULTS

Before stimulation with frusemide, the plasma renin in Group A was 0.79 +/- 0.13 ng angiotensin l/ml per h, while in Group B the corresponding figure was 1.73 +/- 0.38 ng angiotensin l/ml per h. This difference was statistically significant (P= 0.0127). Thirty minutes later the plasma renin level in Group A was 2.43 +/- 0.37 ng angiotensin l/ml per h versus a level of 3.86 +/- 0.53 ng angiotensin l/ml per h in Group B (P= 0.0169). Again, 30 minutes later the level was 2.59 +/- 0.4 ng angiotensin l/ ml per h in Group A, versus 3.79 +/- 0.59 ng angiotensin l/ ml per h in Group B (P= 0.0495).

CONCLUSIONS

We conclude that patients with multiple renal arteries constitute a group who have high plasma renin activity and may therefore be prone to develop arterial hypertension.