Stephen C. Nicholls

Noninvasive diagnosis of renal artery stenosis by ultrasonic duplex scanning.

We retrospectively studied the results of duplex scanning for evaluation of renal artery disease in 158 patients. Satisfactory examinations were achieved in 144 patients (90%). Arteriograms were available for 43 renal arteries. We used the ratio of the peak velocities in the renal artery and the aorta (RAR) to separate nonstenotic arteries (less than 60% diameter reduction) from stenotic arteries (greater than 60% diameter reduction). With an RAR of greater than 3.5 to indicate stenotic lesions, duplex scanning had a sensitivity of 91% (20 of 22 diseased arteries correctly identified) and specificity of 95% (20 of 21 normal or insignificantly diseased arteries correctly identified). One of four occluded arteries was incorrectly interpreted as patent because of misidentification of a collateral vessel. Prospective studies will be necessary to validate this test and establish other criteria for a more detailed classification of renal artery stenosis. The ratio of the end-diastolic to peak systolic velocities in the renal artery (EDR) tended to decrease with increasing serum creatinine levels, presumably because renal vascular resistance increases with end-stage parenchymal disease. EDR may prove useful in the detection of advanced parenchymal disease before renal artery revascularization is attempted.

Rupture in small abdominal aortic aneurysms

BACKGROUND The decision of whether to repair small abdominal aortic aneurysms (AAAs), which are those that are less than 5 cm in diameter, remains controversial. METHODS We describe 161 consecutive patients who were seen at a single urban hospital with ruptured AAAs (rAAAs) and in whom aneurysm size was measured with ultrasound scanning, or rarely computed tomography, en route to the operating room. Eleven patients (6.8%) had AAAs that measured less than 5.0 cm. This group was compared with 150 patients who had rAAAs that were more than 5 cm. RESULTS The mortality rates were similar in both of the groups 70% for small rAAAs versus 66% for large rAAAs. No significant differences were seen between the patients with small and large ruptured aneurysms with respect to the prevalence rates of hypertension (60% vs 50%) or of cardiac disease (20% vs 22%). However, the prevalence rate of obstructive lung disease was significantly different (64% vs 25%; P =.02) as was the rate of diabetes (28% vs 3%; P =.004). Five aneurysms were measured at exactly 5 cm. This suggests that approximately 10% of all aneurysms that rupture in this series do so at 5 cm or less. CONCLUSION In view of the safety of elective repair as compared with the prohibitive risk associated with aneurysm rupture, patients who are at good risk with small AAA (between 4 and 5 cm) should be considered for elective aneurysm resection. For unclear reasons, obstructive lung disease and diabetes are associated with a significantly greater risk for rupture of small AAA. Patients with these risk factors should be given special consideration.

Long-term follow-up and clinical outcome of carotid restenosis******

The efficacy of carotid endarterectomy is dependent on the inherent ability of the operation to prevent stroke as well as the incidence of restenosis and associated symptoms. To examine the long-term effects of restenosis, 301 patients having carotid endarterectomy were followed by serial duplex scanning for an average of 4 years. Carotid restenosis, defined as 50% or greater diameter reduction by duplex scanning, occurred after 78 of the endarterectomies; regression of recurrent stenosis occurred in 20 arteries. By life-table analysis the cumulative incidence of restenosis at 7 years was 31%, and the cumulative incidence of regression was 10%. Thus the prevalence of recurrent stenosis at 7 years was 21%. Restenosis developed in women more frequently than men (p = 0.01). Transient ischemic attack occurred in 12% of patients with restenosis, and stroke occurred in 3%; however, the cumulative incidence of stroke or transient ischemic attack was not statistically different in those patients with and without restenosis. Similarly, cumulative survival at 7 years was no different. Carotid restenosis usually occurs early in the postoperative period and tends to regress or remain stable during long-term follow-up. A conservative approach to treatment appears justified, since transient ischemic attacks and stroke were rarely associated with restenosis.

Operative versus nonoperative management of asymptomatic high-grade internal carotid artery stenosis: Improved results with endarterectomy

In a 4-year period, 129 asymptomatic high-grade (80-99%) internal carotid artery stenoses were identified in 115 patients. Because we previously demonstrated a strong relation between degree of carotid stenosis and subsequent development of ipsilateral related events (stroke, transient ischemic attack, and carotid occlusion), we changed our previous policy and began to offer carotid endarterectomy to good surgical risk patients referred to us with asymptomatic high-grade carotid stenosis. A total of 56 carotid endarterectomies were performed while 73 lesions were followed nonoperatively. Operated and nonoperated groups were similar with regard to age, prevalence of hypertension, cardiac disease, diabetes, and aspirin use. Life table analysis to 24 months revealed a higher rate of stroke (19 vs. 4%, p = 0.08), transient focal neurologic deficits (28 vs. 5%, p = 0.008), and carotid occlusion (29 vs. 0%, p = 0.003) in the nonoperated group. Eight of the 9 strokes in the nonoperated group occurred within 9 months of diagnosis of the high-grade lesion; none were preceded by a transient ischemic attack. There was 1 perioperative stroke (1.8%) but no in-hospital operative deaths and no difference in the late death rates of the two groups. This suggests that the preservation of neurologic status in patients with asymptomatic high-grade internal carotid artery stenosis can be improved by carotid endarterectomy.

Carotid endarterectomy: Relationship of outcome to early restenosis

The results following carotid endarterectomy were prospectively evaluated in 134 patients (145 sides) by repeat ultrasonic duplex scanning and clinical evaluation extending for a period of 4 years. There were 107 men and 27 women in the study group. The perioperative stroke rate was 1.3% and the mortality rate, 0.7%. There were 9 late deaths, of which two were stroke related (1.4%). Focal symptoms occurred in 12 patients on the ipsilateral side, six of which were strokes (one lacunar). The remaining symptoms developed in the presence of moderate degrees of carotid stenosis (less than 50%). There were seven patients who had transient ischemic attacks (TIAs) referable to the operated side, but only two of these were associated with a recurrent high-grade stenosis. During follow-up 32 (22%) patients had recurrent high-grade stenosis. Restenosis regressed in seven, giving a persistent rate of 17.1%. The incidence of restenosis was significantly higher in women (p less than 0.01). By life-table analysis, restenosis occurred early, the majority within 24 months. There was no consistent association between the development of symptoms and the occurrence of restenosis. Therefore, it is concluded that there is no justification for reoperation based on the degree of narrowing observed to prevent subsequent TIAs and strokes.

Carotid artery occlusion: Natural history

During a 5-year period, 212 patients (170 men and 42 women, median age 65 and 64 years, respectively) were diagnosed as having internal carotid artery occlusion. Mean follow-up was 24.9 months. Five-year cumulative survival and stroke-free rates by life-table analysis were 62% and 75%, respectively. Deaths were due to stroke in 7 of 40 patients (17%) and were of cardiac origin in 22 of 40 patients (55%). The strokes were ipsilateral in 20 of 31 patients (65%). No statistically significant difference between the sexes could be demonstrated for either death or stroke, nor was age correlated with stroke during follow-up. Diabetes and hypertension increased the risk of stroke, whereas gender and aspirin consumption had no discernible effect. Endarterectomy of the opposite carotid artery did not significantly affect the natural history but did reduce the stroke rate in the territory of the operated artery. Presenting symptoms were useful for estimating prognosis. Twenty-two of 111 patients referred for stroke (20%) suffered a further stroke and 21 of 111 patients (19%) died (three were stroke-related), whereas of those patients referred for transient ischemic attack (TIA), only 2 of 42 patients (5%) suffered a stroke and none died. TIAs occurred in 23 patients (11%) during follow-up, and these were premonitory for stroke in three cases (13%). The limited value of TIA in predicting stroke and the high mortality rate unrelated to stroke in this group are important considerations when therapy is considered for these patients.

Use of hemodynamic parameters in the diagnosis of mesenteric insufficiency

To evaluate the hemodynamic characteristics of the normal mesenteric circulation, five parameters of the velocity waveforms were measured in 15 normal subjects in the celiac and superior mesenteric arteries (SMA) in the pre- and postprandial periods. It was noted that changes in celiac artery flow after eating was minimal, indicating that this vessels major supply function is not to the gut. SMA parameters showing the most significant and consistent changes after a meal were the diastolic reverse flow and diastolic forward flow (DFF). Four patients referred with symptoms of intestinal angina underwent scanning and subsequent angiography of their mesenteric circulation. All four exhibited loss of reverse flow in the SMA. The change in DFF in the SMA was statistically significant (p = 0.01). Change in peak systolic velocity in the celiac artery was marginally significant (p = 0.05). Angiography revealed that three patients had greater than 90% stenosis of both vessels. The fourth patient had a 90% celiac artery and 65% SMA stenosis. The technique described offers the first noninvasive means of identifying mesenteric insufficiency. It is an effective screening method for a disease entity difficult to verify without selective arteriography. The use of velocity waveform parameters giving good discrimination between normal subjects and those with stenoses of the visceral arteries should reduce both the incidence of missed diagnosis and unnecessary angiography.

Neurologic sequelae of unilateral carotid artery occlusion: Immediate and late

Over a 7-year period (1980 to 1987) 24 patients (18 men: mean age 67 years; range, 52 to 78 years, and six women: mean age 67 years; range, 46 to 82 years) undergoing serial carotid artery duplex scans were observed to progress to unilateral carotid artery occlusion. The occlusions were associated with ipsilateral strokes in six (25%), ipsilateral transient ischemic attacks in four (16%), and the onset of nonhemispheric symptoms in one (5%). Thirteen patients had no symptoms. Follow-up ranged from 4 months to 96 months (mean 39.4 months). Late neurologic events comprised two strokes, three transient ischemic attacks and the onset of nonhemispheric symptoms in six, which in some were disabling. Thirteen patients had no symptoms. Three deaths occurred (one was stroke related). For late events by life-table analysis, the average annual rate over the first 2 years for stroke was 10% and for transient ischemic attack 13%. The combined rate for transient ischemic attack and stroke was 20% per annum. For nonhemispheric symptoms the rate for the first year was 31%. It is concluded that unilateral carotid artery occlusion is associated with an unacceptable incidence of immediate neurologic sequelae and that such patients continue to have a high rate of late neurologic deficits at follow-up. Therefore it seems appropriate that patients who are observed to progress to high-grade stenosis and are therefore at risk for immediate occlusion should undergo prophylactic carotid endarterectomy.

Mesenteric Vein Thrombosis

Mesenteric vein thrombosis, an uncommon but important clinical entity, can cause ischemia or infarction of the small intestine. Mesenteric vein thrombosis was first described nearly a century ago, but

Immediate and long-term results of carotid endarterectomy.

We review the long-term results of carotid endarterectomy in 200 consecutive patients operated on from 1980 to 1987. The patients were part of an ongoing study using duplex scanning to assess the status of the carotid bifurcation before and after endarterectomy. The average follow-up for the patients was 31 months. The indications for surgery were transient ischemic attacks in 87 (43.5%) and stroke in 36 (18%) patients; 77 patients (38.5%) were asymptomatic. In 176 sides (88%), the degree of stenosis exceeded 50% in terms of diameter reduction. The perioperative stroke rate was 2.3% in patients with transient ischemic attacks, 2.8% in patients with strokes, and 1.3% in asymptomatic patients. There was one perioperative death (0.5%). There were five occlusions of the internal carotid artery, one during the perioperative period and four after discharge; in three patients the occlusion was associated with the development of a stroke. There was a restenosis rate of 19.7% secondary to myointimal hyperplasia; such lesions did not appear to contribute to new ischemic events during or after their development. The mean stroke incidence after the decision was made for carotid endarterectomy was 2.8%/yr in the patients with transient ischemic attacks, 6.2%/yr in the patients with stroke, and 0.65%/yr in the asymptomatic patients. The annual death rate was 6% for the entire group, 5.5%/yr in the patients with transient ischemic attacks, 9.2%/yr in the patients with stroke, and 4.6%/yr in the asymptomatic patients.