Renal Artery Stenosis*

A Clinical -Pathologic Study in Normotensiue and Hypertensive Patients

KEITH E. HOLLEY, M.D., JAMES C. HUNT, M.D., ARNOLD L, BROWN, JR., M.D., OWINGS W. KINCAID, M.D. and SHELDON G. SHEPS, M.D.

Rochester, Minnesota

DVANCES in vascular surgery that permit A the re-establishment of blood flow distal to stenotic lesions of the renal arteries, with in- stances of apparent permanent relief of hyper- tension, have reawakened interest in methods of determining more accurately the presence of renal artery lesions in hypertensive patients. Many diagnostic procedures have been ad- vocated. Excretory and retrograde urography, renal arteriography, renal function studies of individual kidneys following bilateral ureteral catheterization, and the use of isotope-labeled substances for external counting over the separate kidneys are among those more fre- quently utilized. Our approach to the diagnostic investigation of such problems has been de- scribed [ 73.

Although arteriography permits excellent visualization of the renal vascular anatomy, determining the functional significance of stenosing lesions of the renal arteries has proved to be more difficult. When hypertension is of relatively recent onset and unilateral renal artery stenosis is associated with evidence of ipsilaterally diminished function, amelioration or even complete relief can be obtained by either surgical revascularization of the involved kidney or nephrectomy. Stenosis of the renal arteries, especially in patients forty years of age or older, is usually a result of atheromatous lesions and is commonly bilateral. The relationship of bi- lateral atheromatous renal artery stenosis to hypertension and the predictability of obtaining relief of hypertension by surgical means are less well established. In many cases of bilateral atheromatous renal artery stenosis, impairment of renal function was essentially equal and ranged from minimal to severe. In the absence of the functional alterations usually noted in unilateral disease, assessment of the functional

significance of bilateral lesions and the selection of patients for surgical intervention have proved difficult.

On occasion we have noted moderate or severe atheromatous disease of the renal arteries at necropsy, or on arteriograms obtained for other purposes in normotensive patients. Such lesions are usually bilateral, and most often located in the proximal portion of the artery adjacent to the aorta. Because of difficulties encountered in predicting the response of hypertensive patients to surgical correction of bilateral atheromatous renal artery stenosis, and because of our observation of atheromas of the renal arteries in normotensive patients, we sought to determine the frequency and severity of renal artery stenosis, aortic atherosclerosis and renal arteri- olar sclerosis in an unselected group of patients at necropsy in the hope of elucidating the rela- tionship of these conditions to hypertension.

MATERIAL AND METHODS

During the periods August 1960 through February 1961 and October 1961 through December 1961, patients were studied at necropsy to determine the frequency and severity of renal artery stenosis and renal arteriolar sclerosis. From October through December 1961 renal arteriography was undertaken at necropsy in addition to the gross and histologic examination. Twenty cases were deleted from final consideration because of the presence of one of the following diseases: glomerulonephritis, polycystic kidneys, diabetic glomerulosclerosis, chronic pyelo- nephritis with renal insufficiency, and acute embolic renal artery occlusion. A total of 295 cases remained for analysis.

At the time of necropsy, aortorenal arteriography was undertaken before removal of the abdominal aorta, renal arteries and kidneys in fifty-one patients. The aorta was cross clamped proximal to the celiac axis and also near the aortic bifurcation. A poly-

* From the Sections of Medicine, Roentgenology, and Experimental and Anatomic Pathology, Mayo Clinic and Mayo Foundation, Rochester, Minnesota. Manuscript received August 12, 1963.

14 AMERICAN JOURNAL OF MEDICINE

Renal Artery Stenosis-Halley et al. 15

ethylene catheter was inserted into the aorta via the severed superior mesenteric artery and secured by ligature. The celiac and inferior mesenteric arteries were ligated to prevent loss of contrast medium. Thirty to 50 ml. of 50 per cent Urokon@ was rapidly injected through the catheter, and a single roentgeno- gram of the aorta, renal arteries and kidneys was obtained.

In ninety-six unselected patients the abdominal aorta, renal arteries and kidneys were removed en bloc to determine the presence or absence of aberrant renal arteries arising separately from the aorta. In the remaining 199 patients the renal arteries were severed distal to their primary division in the hilus of the kidney. The aorta was opened posteriorly in a longitudinal fashion and inspected for evidence of gross atherosclerosis. The renal arteries were cross sectioned at 1 to 3 mm. intervals beginning with their intra-aortic segments and extending into the primary divisions. The maximal degree of stenosis of the ostium and of the proximal, middle and distal thirds of the main renal artery was estimated and recorded. Sections of the more severely stenosed areas of each renal artery were obtained for histologic examination. The kidneys were inspected for evidence of scarring, infarction, atrophy or obstructive uropathy. Multiple sections of the kidneys were obtained for microscopic examination.

All tissues were fixed in 10 per cent buffered formalin. Gross examination of the renal arteries was accomplished prior to fixation in approximately 100 patients and was not delayed for more than seven days in any instance. When necessary, decalcification was effected with ethylenediamine tetra-acetic acid. Sections of paraffin-embedded tissue of 6 to 8 p in thickness were stained in the following manner: hematoxylin and eosin, Verhoeff’s elastic tissue stain counterstained with van Gieson’s stain, and the Mallory-Heidenhain stain.

The degree of abdominal aortic atherosclerosis was estimated and classified in the following manner: minimal sclerosis-no gross involvement or less than one third of the intimal surface involved by fatty streaks or atheromatous fibrosis or plaques; moderate sclerosis-similar involvement of more than one third but less than two thirds of the intimal surface; severe sclerosis-presence of ulcerating or thrombotic atheromas with or without gross calcification or involvement by two thirds or more of the intima by changes similar to those classified as minimal or moderate.

‘Ihe degree of gross renal artery stenosis was estimated and classified in the following manner: minimal stenosis-no narrowing or narrowing not exceeding one fourth of the intraluminal diameter; moderate stenosis-narrowing exceeding one fourth but not exceeding one half of the intraluminal diameter; severe stenosis-narrowing exceeding one half of the intraluminal diameter. With this grading

VOL. 37, JULY 1964

system the degree of stenosis estimated for a given unfixed specimen was essentially the same as that in the fixed state.

Histologic examination of the arteries established the nature of the stenosis and aided in confirming the degree of intraluminal narrowing as previously determined from the gross examination. The degree of renal afferent arteriolar sclerosis was estimated in the following manner: minimal sclerosis-no sclerosis or infrequent involvement of the afferent arterioles by thickening due either to muscular hypertrophy or to hyalinization; moderate sclerosis- similar but more diffuse and severe thickening of the afferent arterioles so that the arteriolar wall is of a diameter equal to that of its lumen; severe sclerosis- diffuse severe afferent arteriolar thickening in which the diameter of the arteriolar wall usually exceeds that of the lumen.

After the gross and histologic study of all subjects had been concluded, the clinical histories were reviewed. The patients were divided into normo- tensive and hypertensive groups. Patients were classified as hypertensive when the diastolic blood pressure had consistently been 100 mm. Hg or more, or funduscopic examination had revealed evidence of hypertension as described by Keith, Wagener and Barker.

RESULTS

A total of 295 patients were available for analysis; 256 were considered normotensive and thirty-nine hypertensive.

Age and Sex Distribution. The 256 normoten- sive patients ranged in age from one to ninety- three years with a mean age of 58.4 years; 159 (62 per cent) were male and ninety-seven (38 per cent) female. The thirty-nine hypertensive patients ranged in age from thirty-four to eighty-one years with a mean age of 64.5 years; twenty (51 per cent) were male and nineteen (49 per cent) female. The frequency and severity of renal artery stenosis by decade and sex are recorded in Figure 1 and Table I.

Abdominal Aortic Atherosclerosis. The degree of atherosclerosis of the abdominal aorta in the 256 normotensive patients was graded as minimal in ninety-two (35.9 per cent), moderate in sixty-five (25.4 per cent) and severe in ninety- nine (38.7 per cent). The degree of similar involvement in thirty-nine hypertensive patients was minimal in five (12.8 per cent), moderate in eight (20.5 per cent) and severe in twenty-six (66.7 per cent). The frequency and severity of abdominal aortic atherosclerosis by decade are recorded in Table II.

Renal Artery Stenosis. The degree of stenosis of the renal arteries in the 256 normotensive

16 Renal Artery Stenosis-Halley et al.

50 N = Normotensive

I H= Hypertensive

2 40 -

9 Severe ; 4 m Mo,,er,,te

lL. 30 - 0

0 Minimal

Age in decades

FIG. 1. Frequency and severity of renal artery stenosis.

TABLE I

RENAL ARTERY STENOSIS IN 256 NORMOTENSIVE AND THIRTY-NINE

HYPERTENSIVE SUBJECTS AT NECROPSY -

I -

I -

Minimal (no.) Moderate (no.) Severe (no.)

-I Total --

: I

-

--

: r

__

Vormotensive Hypertensive

Fe- male Male

Fe- male

_-

_-

0 0 0 0 0 0 2 0 0

_-

Vormotensive Hypertensive Vormotensive Hypertensive

-

Male Fe-

male Male Fe-

male

0 0 0 0 2 1 5 6 4

.- --

0 0 0

Age hr.1 I

Male

o-9 2 10-19 6 20-29 7 30-39 9 40-49 12 50-59 13 60-69 15 70-79 14 80+ 2

Total

.-

-

80 I50 j 7 / 2

-

Male Fe-

male

0 0 0 1 1

14 16 14

7

0 0 0 0 3 2 7 9 8

--

53 29

Fe- male

Fe- male

4 2 7 6

14 13 25 27 18

--

Male Male

2 6 7

12 14 40 46 37 15

_-

__

- 4 ) 4 ( 26 ) 18

patients was graded as minimal in 130 (50.8 lesions. Atherosclerotic lesions were diffusely per cent), moderate in eighty-two (32.0 per scattered throughout the length of the renal cent) and severe in forty-four (17.2 per cent). arteries. However, in 149 (95.5 per cent) of the Among the thirty-nine hypertensive patients 156 patients with moderate or severe stenosis, the degree of involvement was minimal in nine lesions of maximal severity were almost in- (23.1 per cent), moderate in eight (20.5 per cent) variably located at the aortic orifice or within and severe in twenty-two (56.4 per cent). In all the proximal one third of the renal artery, or instances stenosis was caused by atheromatous both. The atheromatous plaques usually ex-

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Renal Artery Stenosis--N&y et al.

TABLE II

ABDOMINAL AORTIC ATHEROSCLEROSIS IN 256 NORMOTENSIVE AND THIRTY-NINE

HYPERTENSIVE PATIENTS AT NECROPSY

17

Am-tic Atherosclerosis

3s Normotensive (no.)

I

Minimal Moderate Severe

_____ 92

6 8

14

14 1

12 2 1

11 4

9 3

3 3 1

Hypertensive (no.) Renal Artery

Stenosis Age (yr.) Subjel

Minimal

6 2 1 1 1

4 9 3

5 3 6

8 9 1

6 11 10

8 7 8 12 1 11

1 6 2 13 3 6

Moderate

1

1

3 1

. 1 1

Severe

6 Minimal 8 Minimal

14 Minimal

14 Minimal 1 Moderate 3 Severe

21 Minimal 4 Moderate 3 Severe

22 Minimal 19 Moderate 12 Severe

29 Minimal 25 Moderate 17 Severe

18 26 20

7 15 11

-

Minimal Moderate Severe

Minimal Moderate Severe

O--9 10-19 20.-29

40-49

50-59

60-69

70-79

8Oi-

1

1

1

1 1

.

_ --

- 65 99 5 8 26 I - 295 Total

- - -

tended for not more than 2 to 3 mm. of the longitudinal axis of the renal arteries in patients with minimal stenosis and seldom exceeded 1.2 cm. in patients with severe stenosis. The distribution by decade, sex and severity is recorded in Table I and by unilateral or bi- lateral localization in Table III. Some of the renal artery lesions are illustrated in Figures 2 and 3.

Renal Arteriolar Sclerosis. The degree of renal arteriolar sclerosis in the 256 normotensive patients was graded as none in 179 (69.9 per cent), minimal in sixty-five (25.4 per cent), moderate in eleven (4.3 per cent) and severe in one (0.4 per cent). Similar grading of arteriolar sclerosis in the thirty-nine hypertensive patients

VOL. 37, JULY 1964

revealed none in seven (17.9 per cent) and minimal involvement in fifteen (38.5 per cent), moderate involvement in ten (25.7 per cent) and severe involvement in seven (17.9 per cent). It was not possible to distinguish histologically between the afferent arteriolar sclerosis in hypertensive patients and that in normotensive patients. The distribution by age, severity and relationship to renal artery stenosis is recorded in Table IV, and an example of arteriolar sclerosis is illustrated in Figure 4.

Kidney Weight. The weight of the individual kidneys was obtained in all cases in order to determine the differences and to compare these differences with the presence and degree of renal artery stenosis. After all the cases involving

18 Renal Artery Stenosis-Halley et al.

TABLE III

LOCALIZATION OF MODERATE AND SEVERE RENAL ARTERY STENOSIS IN 126 NORMOTENSIVE AND

THIRTY HYPERTENSIVE SUBJECTS STUDIED AT NECROPSY

Age (~r.1

o-9 10-19 20-29 30-39 40-49 50-59 60-69 70-79 SO+

Total

-

Moderate (no.) Severe (no.)

Unilateral Bilateral Unilateral Bilateral

Normo- Hyper- Normo- Hyper- tensive tensive tensive tensive

-

Normo- Hyper- Normo- Hyper- tensive tensive tensive tensive

0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 3 0 1 0 9 1 7 2

10 1 13 1 6 0 17 3 6 0 9 0

___-

34 2 48 6

0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 1 1 1 1 0 1 1 8 2 1 2 10 4 3 0 10 7 3 0 6 2

9 6 35 16

-

renal cysts, neoplastic lesions or other paren- chymal diseases were eliminated, there were 235 cases considered satisfactory for study. The percentage differences in kidney weight ex- pressed in relation to the larger kidney for 201 normotensive and thirty-four hypertensive pa- tients are recorded in Table v.

In thirteen of thirty-five normotensive patients and in four of seven hypertensive patients with moderate or severe unilateral renal artery

FIG. 2. Transverse section from proximal third of right renal artery in a normotensive man fifty-two years of age. The degree of stenosis was graded as severe. Verhoeff’s elastic tissue and van Gieson’s stain, original magnifica- tion X 10.

stenosis the difference in the weight of the two kidneys was 15 per cent or more. In five of the normotensive patients, the larger kidney was supplied by the stenosed renal artery.

In twelve of 106 normotensive patients and in none of nine hypertensive patients with minimal renal artery stenosis, the difference in the weight of the two kidneys was 15 per cent or more.

Thirty-six normotensive and five hypertensive patients whose kidneys were weighed had

FIG. 3. Proximal third of right renal artery with severe stenosis in a sixty-three year old hypertensive woman. Verhoeff’s elastic tissue and van Gieson’s stain, original magnification X 10.

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Renal Artery Stenosis-Halley et al.

TABLE IV RENAL AFFERENT ARTERIOLAR SCLEROSIS IN 256 NORMOTENSIVE AND THIRTY-NINE

HYPERTENSIVE SUBJECTS AT NECROPSY

19

Age (yr. Subjects

(no. )

-

--

Renal Artery

Stenosis Normotensive (no.) Hypertensive (no.)

None 1 Minimal 1 Moderate ~ Severe I None 1 Minimal / Modrze

o-9 6 Minimal 10-19 8 Minimal 20-29 14 Minimal

6 8

l4 I

30-39 14

1 3

Minimal 12 Moderate 1 Severe

2

40-49 21 Minimal 16 4

4 Moderate 2 2 3 Severe 1

so-59 22 Minimal 16 4 19 Moderate 13 3 12 Severe 6 2

60-69 29 Minimal 17 5 25 Moderate 11 10 17 Severe 4 5

70-79 18 Minimal 13 4 26 Moderate 14 8 20 Severe 5 7

80+ 7 Minimal 6 1

15 Moderate 9 5 11 Severe 5 3

Total 295

--

- 179

I - 65

-

Arteriolar Sclerosis

-

I --. .-

.l

1 ,

1 .::

1 1

3

1 I

~ .’ ~ 1

:

1 2

I

1

2 1 2

1’ 3

__- ,___,

11 * I 7 I

_I_

I - 15 ~ 10 I 7

bilateral moderate renal artery stenosis. A difference of 15 per cent or more in the weight of the two kidneys was found in only six of the normotensive patients and in none of the hyper- tensive patients.

In all ten normotensive and five hypertensive patients with bilateral severe renal artery stenosis, the difference between the weight of the kidneys was less than 15 per cent.

Fourteen normotensive and eight hyper- tensive patients whose kidneys were weighed had severe stenosis of the artery to one kidney and moderate stenosis of the contralateral renal artery. In five of the fourteen normotensive patients, the kidney with the more severely stenosed renal artery weighed at least 15 per

VOL. 37, JULY 1964

FIG. 4. Renal arteriole showing severe arteriolar sclerosis in a fifty year old hypertensive woman with bilateral severe renal artery disease. Hematoxylin and eosin stain, original magnification X 200.

20 Renal Artery Stenosis-Halley et al.

TABLE V

PERCENTAGE DIFFERENCE IN KIDNEY WEIGHT OF 201

NORMOTENSIVE AND THIRTY-FOUR HYPERTENSIVE

SUBJECTS WITH MODERATE OR SEVERE RENAI.

ARTERY STENOSIS STUDIED AT NECROPSY *

Renal Artery Stenosis

Normotensive

(“0.)

Hypertensive

(“0.)

Unilateral Moderate. severe.

Bilateral Minimal. Moderate. severe. Severe and mod-

et-ate. --_

Total.

8$ 4%

33

0

0

2 0 1 4

9 0 5 0 5 0

71 1

I 0

3 29) 5 I O

* Percentage difference _ weight of larger kidney minus weight of smaller kidney

weight of larger kidney x 100.

t Three patients had larger kidney on side with renal artery stenosis. $ One patient had larger kidney on side with renal artery stenosis.

cent less. A similar decrease in kidney weight was noted in one of eight hypertensive patients.

Aberrant Renal Arteries. Specific investigation was undertaken in ninety-six patients (eighty- five normotensive and eleven hypertensive) to determine the frequency and location of aberrant arteries supplying the kidneys. Aber- rant arteries arising separately from the ab- dominal aorta were observed in eight patients (six normotensive and two hypertensive). In six patients the aberrant arteries were unilateral, in two bilateral. Of the six unilateral aberrant renal arteries, four supplied the right kidney and two the left kidney. Three of the unilateral aberrant arteries were moderately or severely stenosed (bilateral moderate or severe main renal artery stenosis was also present). The two patients with bilateral aberrant arteries had a single aberrant artery to the upper pole of each kidney. One of the patients with bilateral aberrant arteries had moderate stenosis of all aberrant and main renal arteries.

Renal Arteriography. Renal arteriography was performed at necropsy in fifty-one patients (forty-six normotensive and five hypertensive). (Fig. 5.) Findings were similar to those on gross and histologic examination in all but five patients. At necropsy these five patients were

found to have moderate or severe stenosis of the aortic orifice of the renal arteries, but the arteriograms were interpreted as showing no abnormalities. Subsequent review of the arterio- grams clearly revealed severe atherosclerotic changes in the region of origin of the renal arteries in two of these patients, and no abnor- malities in the remaining three.

COMMENTS

It is clear from the present study that moder- ate or severe renal artery stenosis is by no means confined to patients with hypertension. Although 77 per cent of the hypertensive patients had moderate or severe stenosis, similar lesions were present in 49 per cent of normotensive patients. This fact is emphasized further if only patients fifty years of age or older are considered. Of the hypertensive patients fifty years of age or more, 76 per cent had moderate or severe renal artery stenosis, whereas 64 per cent of the normotensive patients were similarly involved. The incidence in normotensive patients is similar to that noted by Lisa and associates [3] but is far greater than that reported by Blackman [4] and by Richardson [S]. If the patients less than fifty years of age are considered, the discrepancy between the presence of moderate and severe renal artery stenosis in normotensive patients as compared with hypertensive patients is greater. Thus, in the sixty-nine normotensive patients, only seven had moderate or severe renal artery stenosis; whereas in the hyperten- sive patients, four of five had a similar degree of involvement. On the basis of this small series, the interpretation could be that the etiologic significance of renal artery stenosis is greater in hypertensive patients under fifty years of age than in those fifty years of age or over.

The significance of renal arteriolar sclerosis with or without associated renal artery stenosis has been the subject of previous investigations [&9]. Smith [S] noted that hyaline degeneration of the afferent arterioles of the kidney is a manifestation of aging but is increased in hyper- tensive patients. From a review of 5,000 necropsy protocols, Oppenheimer and asso- ciates [7] found eighteen patients who had unilateral renal artery stenosis; fifteen were hypertensive and three normotensive. All the hypertensive patients had bilateral renal arteri- olar sclerosis, whereas the three normotensive patients had no arteriolar disease. From these observations they concluded that renal artery

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Renal Artery Stenosis-Halley et al.

atherosclerosis was the result rather than the cause of hypertension. Moritz and Oldt [8], reporting on 100 normotensive and 100 hyper- tensive patients, noted that 12 per cent of the former and 97 per cent of the latter had some degree of renal arteriolar sclerosis. Three hyper- tensive patients without arteriolar sclerosis were considered to have sufficient athero- sclerotic disease of the renal arteries to reduce renal blood flow. A detailed description of the histologic findings was not reported. Wilson and Byrom [9] demonstrated that unilateral renal artery stenosis in rats will produce arteriolar disease in the contralateral kidney; this closely resembles the changes seen in the human kidney in malignant hypertension. These investigators emphasized the absence of intrarenal hypertensive vascular changes distal to the renal artery stenosis. Freeman and Hartley [70] described a patient with a solitary kidney and malignant hypertension who died in renal failure. At necropsy, the renal arterioles were normal; the abdominal aorta was severely atherosclerotic; and the ostium of the solitary renal artery was markedly stenosed. Richardson [5] noted that three of twenty-five patients with atheromatous disease of one or both renal arteries had no intrarenal hypertensive changes. He considered but rejected the thesis that renal artery stenosis might protect the kidney distal to the lesion from hypertension The potential clinical importance of protection of the ipsi- lateral kidney by stenosis of the main renal artery has been emphasized by Bauer and Forbes [77], Laforet [72], and Howard and associates [ 731.

In the present study, only twelve (5 per cent) of the normotensive patients had moderate or severe sclerosis of the afferent renal arterioles. Ten of these were sixty years old or more; sclerosis was graded as severe in only one. Similar lesions were present in seventeen (44 per cent) hypertensive patients. Fourteen of these were sixty years of age or older. In all of eight hypertensive patients with unilateral moderate or severe renal artery stenosis, afferent arteriolar sclerosis was absent or less severe in the kidney with the stenosed renal artery than in the contralateral kidney.

The effect of unilateral renal artery stenosis on kidney weight is noted in Table v. In thirteen of the thirty-five normotensive patients with unilateral renal artery stenosis of moderate or severe degree, one kidney was 15 per cent or

VOL.. 37, JULY 1964

more smaller than its mate. In eleven of the thirteen, the smaller kidney was on the side with the renal artery stenosis. In four of seven hyper- tensive subjects with similar unilateral lesions, the kidney distal to the stenosis was lighter in weight by 15 per cent or more.

The incidence of multiple or aberrant renal arteries has been investigated by necropsy dissections and by renal arteriograms [74-781. Some investigators have suggested an association between aberrant renal arteries and hyper- tension [ 74,751. In a recent study of the renal arteriograms of 381 hypertensive patients Geyer and Poutasse [77] found that the incidence of multiple renal arteries in patients with and without roentgenographic evidence of renal artery disease was approximately the same. In the present series, six of eighty-five normotensive and two of eleven hypertensive subjects were found to have multiple or aberrant renal arteries. One of the two hypertensive subjects

FIG. 5. A, normal postmortem renal arteriogram showing polyethylene catheter in superior mesenteric artery. Main renal arteries had minimal histologic evidence of atherosclerosis. (Cross clamping of aorta is evident at base of film.) B, postmortem renal arteriogram with evidence of narrowing in both renal arteries but more pronounced in right renal artery (arrow). Histologically, degree of stenosis was graded as severe.

22 Renal Artery Stenosis-Halley et al.

had stenosis of all main and aberrant renal arteries. The small number of hypertensive patients in this series does not permit conclusions as to the incidence of aberrant arteries or to the incidence of renal artery stenosis in the patient with aberrant arteries.

The degree of aortic atherosclerosis was essentially the same in normotensive and hyper- tensive patients when the patients fifty years old or more were considered. In this age group, moderate or severe atherosclerosis was present in 82 per cent of the normotensive and in 91 per cent of the hypertensive patients.

The accuracy of roentgenologic study of the renal arteries was reconfirmed in this study. However, the difficulty of recognizing stenosis at the orifice of the renal artery was emphasized by the fact that in three such patients the diagnosis could not be made from the post- mortem renal arteriograms.

From this study it would appear that demon- stration of unilateral or bilateral renal artery stenosis does not warrant the conclusion that stenosis is responsible for the associated hyper- tension. This is particularly true in patients who are more than fifty years of age. Ancillary studies must be undertaken to determine the clinical significante, if any, of the renal artery stenosis before appropriate decisions regarding manage- ment can be reached.

SUMMARY

Moderate or severe renal artery stenosis was found in 53 per cent of 295 unselected patients examined at necropsy; it was present in 49 per cent of 256 normotensive patients and:in 77 per cent of thirty-nine hypertensive patients. Severe stenosis of the renal arteries was uncommon in normotensive patients less than fifty years of age; thereafter, the frequency increased with increasing age. Afferent arteriolar sclerosis of a moderate or severe degree was uncommon in normotensive patients less than sixty years old. The presence of atheromatous narrowing of the main renal arteries does not necessarily indi- cate a causal relationship to the presence of systemic hypertension.

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13. HOM’ARD. J. E.. BERTHRONG. M.. GOULD. D. M. and YENDT; E. ‘R. Hypertension resulting from uni- lateral renal vascular disease and its relief by nephrectomy. Bull. Johns Hopkins Hosp., 94: 51, 1954.

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