CHRONIC PYELONEPHRITIS AND ARTERIAL HYPERTENSION

Renal denervation for hypertension

Systemic hypertension is a major burden to the individual and society. Its association with major adverse cardiac and cerebral events and favorable effects of antihypertensive therapy are undisputed. However, despite multidrug therapy, blood pressures are frequently suboptimally controlled. Moreover, adverse drug effects often interfere with patients' lifestyles and affect compliance. Therefore, alternative treatment strategies have been explored. Most recently, attention has been redirected to the sympathetic nervous system (SNS) in the pathogenesis of hypertension. In addition, interruption of the renal SNS in humans with resistant hypertension has been studied with promising results. The following review provides an overview of the anatomy and physiology of the renal SNS, the rational for manipulating the SNS, and the results of therapeutic renal sympathetic denervation.

Vesicoureteral reflux and reflux nephropathy

Primary vesicoureteral reflux (VUR) is the commonest congenital urological abnormality in children, which has been associated with an increased risk of urinary tract infection (UTI) and renal scarring, also called reflux nephropathy (RN). In children, RN is diagnosed mostly after UTI (acquired RN) or during follow-up for antenatally diagnosed hydronephrosis with no prior UTI (congenital RN). The acquired RN is more common in female children, whereas the congenital RN is more common in male children. This observation in children might help explain the differences in the clinical presentation of RN in adults, with males presenting mostly with hypertension, proteinuria, and progressive renal failure as compared with females who present mostly with recurrent UTI and have a better outcome. Known risk factors for RN include the severity of VUR, recurrent UTI, and bladder-bowel dysfunction; younger age and delay in treatment of UTI are believed to be other risk factors. Management of VUR is controversial and includes antimicrobial prophylaxis, surgical intervention, or surveillance only. No evidence-based guidelines exist for appropriate follow-up of patients with RN.

Renin-Dependent Hypertension Caused by Nonfocal Stenotic Aberrant Renal Arteries

We have identified 2 relatively young patients with significant hypertension, an elongated single aberrant renal artery supplying blood to a renal segment, and evidence for localization of the elevated plasma renin activity to the side and vein draining the affected kidney. Furosemide-induced diuresis and acute oral captopril stimulated the renal vein/contralateral renin ratios to 4.3:1 and 6.5:1 in patients 1 and 2, respectively. These renal vein ratios are significantly higher than normal (>3:1 under similar conditions). Partial resection of the portion of the kidney affected by the aberrant tortuous artery led to a marked reduction in blood pressure in patient 1. Patient 2, not an operative candidate, responded satisfactorily to use of a converting enzyme inhibitor, which helped to confirm the dependency of the blood pressure on the abnormal flow relationship existing within that aberrant artery and the kidney. We believe these 2 patients are representative of a small but distinct subgroup within the larger number of patients with elongated single or multiple renal aberrant arteries. Each aberrant artery had no focal stenosis, although a decrease in flow relative to the tissue perfusion demands was apparent from the marked activation of the renin-angiotensin system in the venous system draining that artery. The increased length of such vessels may contribute to their decreased flow, although their average diameter may reside just above such a critical value for a normal length vessel. This new syndrome, involving more than one component of the flow/resistance relationship, has been overlooked when renin-dependent forms of hypertension are considered.

Atherosclerotic renovascular disease in chronic heart failure: should we intervene?

Renal artery stenosis (RAS) is most commonly caused by atherosclerosis, which is also the most common cause of chronic heart failure (CHF). One-third of patients with CHF are reported to have significant renovascular disease. The presence of RAS confers a worse outcome in studies of hypertension and coronary disease, though data are lacking for patients with CHF. As the kidney is intricately involved in the fluid retention that occurs in CHF, an adverse effect of RAS on outcome would be expected. Presentations of RAS in CHF include flash pulmonary oedema, hypertension, worsening of CHF, and worsening renal function. RAS commonly progresses and may cause worsening of renal function in patients with CHF and previously stable renal function. A variety of investigations that can safely and accurately identify RAS in CHF are available, although none is recommended in current guidelines for the management of CHF. Treatment for RAS, whether for hypertension, for renal dysfunction, or for pulmonary oedema, is at the discretion of the physician due to the lack of adequate randomized controlled trials demonstrating the efficacy and safety of intervention. As it is not clear how RAS should be managed in CHF, screening cannot be advocated. Currently, a multicentre randomized outcome trial, which includes a cohort of patients with RAS and CHF, is in progress to provide answers in this area of uncertainty.

Revisiting the role of nephrectomy for advanced renovascular disease

BACKGROUND

Despite the advances in antihypertensive therapy and renal revascularization, there remains a group of patients in whom renovascular disease leads to renal atrophy and treatment-resistant hypertension.

METHODS

We performed an observational cohort study in which we reviewed blood pressures, renal function, and predictors of response in 74 patients who underwent nephrectomy of a small kidney for uncontrolled hypertension between 1990 and 2000.

RESULTS

The median age of the patients was 65 years; 43 (58%) were women. Thirty-five patients (47%) underwent nephrectomy as part of combined revascularization of the contralateral kidney. Associated atherosclerotic diseases were common (28% to 49%), as were prior renal revascularization (21 [28%]) and hypertensive urgency/emergencies (23 [31%]). The mean (+/- SD) long axis of the affected kidney was 8 +/- 2 cm, and the mean function of the kidney (based on radioisotope renography) was 12% +/- 11% of total renal function. The average systolic blood pressure fell from 168 +/- 19 mm Hg to 136 +/- 18 mm Hg (P <0.0001) and diastolic blood pressure declined from 88 +/- 10 mm Hg to 76 +/- 9 mm Hg (P <0.0001) at the most recent available clinic visit (mean follow-up, 4.1 +/- 2.6 years). In addition, the number of antihypertensive medications decreased from 3.2 +/- 1.1 to 2.2 +/- 1.5 (P <0.0001). Renal function remained stable. Results were similar (preoperative blood pressure of 165/88 mm Hg taking three medications to 137/77 mm Hg taking two medications) among the 39 patients who had a nephrectomy without contralateral revascularization.

CONCLUSION

Our results suggest that in selected patients with resistant hypertension and renal artery disease that has resulted in atrophic kidneys with reduced function, nephrectomy can improve blood pressure control without further loss in overall renal function.

Nephrectomy in unilateral chronic pyelonephritis. A long-term follow-up study

In order to study the effectiveness of unilateral nephrectomy as a treatment for chronic unilateral pyelonephritis, 15 consecutive patients who had undergone this operation were followed up. The patients had been operated on 8.9 years (mean) earlier. All of the 15 patients had had recurrent urinary tract infections prior to the operation, 11 of them had had pyelonephritis for between 1 and 19 (mean 6.7) years. One patient only had had a verified episode of urinary tract infection during the follow-up period. All 15 patients were hypertensive prior to the operation. At the time of follow-up, 7 patients were normotensive without drugs, and 2 were normotensive with a reduced dosage of antihypertensives. The mean systolic blood pressure went down from 180 to 150 mm Hg, and the mean diastolic pressure from 109 to 88 mm Hg. This operation can thus be recommended in selected cases of unilateral chronic pyelonephritis with hypertension.

Renal venous renin ratio as a predictor of improvement in hypertension following nephrectomy for unilateral renal disease

Renal venous renin ratio (RVRR) was measured in twenty hypertensive patients before removal of a kidney for unilateral, parenchymal renal disease. They were then followed for 1.3-9 y. Hypertension was cured or improved in six of eight patients with positive unstimulated and stimulated ratios, in none of five whose ratios became positive only on stimulation, and in one of seven with all ratios negative. Patients improved or cured by surgery had a significantly shorter duration of hypertension and a significantly lower serum creatinine after nephrectomy. Unstimulated RVRR was a reliable predictor of the effect of unilateral nephrectomy on blood pressure level.

Curable hypertension. Usefulness of renal vein renin ratio

A case of severe hypertension in an adolescent male is presented. Initial evaluation of hypertension revealed a unilateral nonfunctioning kidney with no lateralization of renal vein renin ratio. Following 10 months of medical therapy, lateralization of renal vein renin was demonstrated, with subsequent cure of hypertension following nephrectomy.

Surgically correctable hypertension of renal origin in childhood

Since 1960, 22 children were treated for surgically correctable hypertension or renal origin. The series included two children with tumors, two with hydronephrosis from ureteropelvic junction obstruction, nine in whom one kidney was atrophic, and nine with renal artery narrowing from fibromuscular dysplasia (with bilateral involvement in two). Hypertension was cured in the cases with tumors and ureteropelvic junction obstruction. It was also cured in four of the nine patients with an atrophic kidney and in five of the nine with a narrow renal artery. In those not cured hypertension was more easily controlled by medication. One patient died from brain hypoxia during surgery. About 10 percent of the children investigated for hypertension at the Massachusetts General Hospital proved to have a surgically correctable cause of renal origin.

Renal artery stenosis in children

Because high blood pressure in children is rare and most of these patients are asymptomatic, many are overlooked until they present with a hypertensive crisis or irreparable damage. Most children with renal artery stenosis are asymptomatic and the hypertension is detected only by blood pressure recording during physical examination. Angiography is the most helpful diagnostic study. It is generally agreed that renal artery lesions in children should be considered for surgical correction. An illustrated case is described.

Role of nephrectomy in the treatment of non-functioning or very poorly functioning unilateral tuberculous kidney

We reviewed 300 consecutive cases of genitourinary tuberculosis at Wrightington Hospital from 1961 to 1978. There were 73 patients with non-functioning or poorly functioning kidneys who underwent nephrectomy after at least 6 weeks of intensive chemotherapy with 3 antituberculous drugs. Three of 4 patients with unilateral non-functioning kidneys who did not have a primary nephrectomy had delayed complications. Late complications of in situ non-functioning tuberculous kidneys included draining flank sinuses, abscesses and hypertension. These complications can occur years after completion of chemotherapy, even in sterile organs. The incidence of hypertension in this series was 11.3 per cent. The incidence of hypertension in patients with unilateral non-functioning or poorly functioning tuberculous kidneys was 23.2 per cent (p less than 0.005). Two-thirds of the hypertensive patients with severe unilateral tuberculous nephropathy benefited by a decrease in blood pressure after nephrectomy. Removal of these kidneys does not cause a significant loss of renal function. The perioperative morbidity and mortality of the procedure should be minimal in a generally younger population. It is concluded that primary nephrectomy is an important adjunct in the comprehensive management of the unilateral non-functioning kidney.

Unilateral chronic pyelonephritis and hypertension: coincidental or causal relationship?

Three patients with well documented unilateral chronic pyelonephritis (UCP) of bacterial origin, one hypertensive and two normo-tensive, were presented. Removal of the contracted kidney in the hypertensive patient did not eradicate the hypertension. An attempt was made to define UCP as closely as possible. The clinical, roentgenologic, bacteriologic, functional and pathologic criteria of UCP was described. But, as other conditions may mimic the roentgenologic, functional and pathologic picture of UCP, a history of recurrent urinary tract infection accompanied by a documented unilateral renal bacteriuria is the basic requirement for a sustained diagnosis of UCP. In view of these more exacting criteria in the diagnosis of UCP, and its water and salt-losing functional pattern, UCP is a rare cause of hypertension, in the majority of cases the association of UCP with hypertension is merely coincidental.

Renovascular hypertension: pathophysiology, diagnosis, and treatment

Renovascular hypertension can result from renal artery lesions involving the main renal artery, or its branches. It is generally felt that the elevation of blood pressure results from excessive systemic vasoconstriction secondary to enhanced renin secretion by one or part of one kidney. Renin secretion is enhanced because of constriction of the renal artery and resultant intrarenal ischemia. Clinically patients cannot be distinguished from those with essential hypertension and diagnosis must be made with arteriography although urography and isotope renography may suggest the diagnosis. Surgical cure can be predicted if differential renal vein renin ratios lateralize but a non-lateralizing study does not necessarily mean that surgery will fail. In properly selected patients, surgical results are excellent.

Renal artery false aneurysm. An unusual complication of prosthetic patch angioplasty

False aneurysm formation in a twenty-nine year old black woman treated for renovascular hypertension secondary to fibromuscular hyperplasia by knitted Dacron prosthetic patch angioplasty is reported. Etiologic mechanisms are discussed. The most likely factors leading to false aneurysm formation in this patient are disproportionate compliance between the arterial wall and the prosthesis and increased rigidity of the prosthesis, associated with increased shearing and vibratory stress. This patient was treated successfully by resection of the prosthetic path and involved artery with end-to-end reanastomosis of the artery.

Renovascular hypertension from renal artery compression by congenital bands

Renal artery compression by fibromuscular bands containing sympathetic nerves and ganglia was encountered in 3 of 75 patients with renovascular hypertension. The hypertension was successfully managed by resection of the bands. The absence of mortality and morbidity dictates that the "stenotic" area of the renal artery be explored, especially in children and adults with minimal angiographic evidence of visceral atherosclerosis, before proceeding with a bypass graft to the renal artery.

Hypertension associated with unilateral renal disease in childhood. Report of two cases and review of the literature

Two girls are described, aged 7 and 10 years respectively, who presented with arterial hypertension associated with unilateral kidney disease. Both were cured by nephrectomy, according to criteria for cure which are described in the paper. Only 45 similar cases could be found in the literature; these results are summarized and compared with those obtained in adult patients. The cure rate in children was 76%; similar large series including patients of all ages, but consisting predominantly of adults, show cure rates of only about 25%. It is inferred that the age of the patient is an important factor in determining prognosis, and should be considered in the selection of patients for nephrectomy. Methods of investigation of these patients, and possible mechanisms concerned in the pathogenesis of the hypertension, are briefly discussed.

Genito-urinary tuberculosis. A study of the disease in one unit over a period of 24 years

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