Cameron M. Akbari

Endothelium-dependent vasodilatation is impaired in both microcirculation and macrocirculation during acute hyperglycemia

PURPOSE Endothelial dysfunction is associated with atheromatosis and is a common finding with diabetes. We have studied the effects of acute hyperglycemia on the endothelium-dependent vasodilatation of both the microcirculation and the macrocirculation of healthy subjects. Because of the presence of endothelial dysfunction with diabetes, we hypothesize that acute hyperglycemia causes impaired endothelial-dependent responses. METHODS Twenty healthy subjects (15 men, 5 women) with a mean age of 32.3 years (range, 23 to 49 years) were examined during fasting conditions and at 1 hour after the ingestion of 75 g of glucose. The endothelium-dependent vasodilatation of the brachial artery, a conduit vessel, was evaluated with high-resolution ultrasound scan to measure the changes in the vessel diameter induced with reactive hyperemia. In the microcirculation, the endothelial function was assessed by measuring the changes in the erythrocyte flux after the acetylcholine iontophoresis. RESULTS The brachial artery endothelium-dependent dilatation was greater during fasting as compared with the response after the glucose load was administered (11.7% [8.3 to 14.3] vs 4.2% [1.5 to 9.6]; P < .001; median, first, and third quartile). Both peak and average blood flow velocities during the hyperemic response were higher after the administration of the glucose load as compared with the fasting period (P < .05), but no changes were found in the blood flow volume. During fasting, microcirculatory endothelial-dependent vasodilatation was also significantly greater than the response after the administration of the glucose load (1293% [591 to 1856] vs 863% [385 to 1180]; P < .01). CONCLUSIONS In healthy subjects, the ingestion of a glucose load impairs the endothelial-dependent vasodilation in both the microcirculation and the macrocirculation. Because impairment of endothelial responses is associated with the early changes of atherosclerosis, it is possible that prolonged hyperglycemia and endothelial dysfunction may lead to the early and accelerated atherosclerosis of diabetes. Further studies are necessary to examine the long-term effects of hyperglycemia.

Diabetes and peripheral vascular disease

Diabetes mellitus is found in as many as 13 million people nationally, or 5.2% of the US population, and more than 650,000 new cases are diagnosed annually.1 Clinical data that link diabetes to vascular disease are derived from several large epidemiologic studies. The Framingham Study of more than 5000 subjects showed that diabetes is a powerful risk factor for atherosclerotic coronary and peripheral arterial disease, independent of other atherogenic risk factors, with a relative risk averaging two fold for men and three fold for women.2 The Framingham Study results also confirmed that the risk of stroke is at least 2.5-fold higher in patients with diabetes,3 a finding that has been confirmed in other large epidemiologic studies.4,5 Moreover, diabetes is strongly associated with atherosclerosis of the extracranial internal carotid artery and thus imparts an additional independent risk of stroke.6 PATHOPHYSIOLOGY OF VASCULAR DISEASE AND COMPLICATIONS OF DIABETES MELLITUS Overview. Many of the clinical complications of diabetes may be ascribed to alterations in vascular structure and function, with subsequent end-organ damage and death. Specifically, two types of vascular disease are seen in patients with diabetes: a nonocclusive microcirculatory dysfunction involving the capillaries and arterioles of the kidneys, retina, and peripheral nerves, and a macroangiopathy characterized by atherosclerotic lesions of the coronary and peripheral arterial circulation.7-10 The former is relatively unique to diabetes, whereas the latter lesions are morphologically similar in both patients with and without diabetes. Retinopathy is the most characteristic microvascular complication of diabetes, and population-based study results have identified a correlation between its development and the duration of diabetes.11 Similar correlations have been found with nephropathy, neuropathy, and diabetes,12 with perhaps the strongest evidence coming from the Diabetes Control and Complications Trial. The results from the Diabetes Control and Complications Trial clearly showed a delay in the development and progression of these microvascular complications with intensive glycemic control, thus supporting the direct causal relationship between hyperglycemia, diabetes, and its microvascular sequelae.13 These and other clinical trials have provided the rationale for experimental studies investigating the fundamental pathophysiology of microvascular and macrovascular disease in diabetes mellitus. Microvascular dysfunction in diabetes is mani

Efficacy of dorsal pedal artery bypass in limb salvage for ischemic heel ulcers

PURPOSE Although pedal artery bypass has been established as an effective and durable limb salvage procedure, the utility of these bypass grafts in limb salvage, specifically for the difficult problem of heel ulceration, remains undefined. METHODS We retrospectively reviewed 432 pedal bypass grafts placed for indications of ischemic gangrene or ulceration isolated to either the forefoot (n = 336) or heel (n = 96). Lesion-healing rates and life-table analysis of survival, patency, and limb salvage were compared for forefoot versus heel lesions. Preoperative angiograms were reviewed to evaluate the influence of an intact pedal arch on heel lesion healing. RESULTS Complete healing rates for forefoot and heel lesions were similar (90.5% vs 86.5%, P =.26), with comparable rates of major lower extremity amputation (9.8% vs 9.3%, P =.87). Time to complete healing in the heel lesion group ranged from 13 to 716 days, with a mean of 139 days. Preoperative angiography demonstrated an intact pedal arch in 48.8% of the patients with heel lesions. Healing and graft patency rates in these patients with heel lesions were independent of the presence of an intact arch, with healing rates of 90.2% and 83.7% (P =.38) and 2-year patency rates of 73.4% and 67.0% in complete and incomplete pedal arches, respectively. Comparison of 5-year primary and secondary patency rates between the forefoot and heel lesion groups were essentially identical, with primary rates of 56.9% versus 62.1% (P =.57) and secondary rates of 67.2% versus 60.3% (P =.50), respectively. CONCLUSION Bypass grafts to the dorsalis pedis artery provide substantial perfusion to the posterior foot such that the resulting limb salvage and healing rates for revascularized heel lesions is excellent and comparable with those observed for ischemic forefoot pathology.

Diabetes mellitus: A risk factor for carotid endarterectomy? ☆ ☆☆

PURPOSE Symptomatic cerebrovascular disease is more common in patients who have diabetes mellitus than in the nondiabetic population, even when matched for associated risk factors. Although the safety and efficacy of carotid endarterectomy has been established by NASCET and ACAS, several small studies have noted an increased rate of perioperative neurologic morbidity in patients with diabetes. METHODS Data for all patients who underwent carotid endarterectomy at a single institution from Jan. 1990 to Dec. 1995 were prospectively entered into a computerized vascular registry and form the basis of this report. RESULTS Of 732 carotid endarterectomy procedures performed, 284 (39%) were performed in patients who had diabetes mellitus. Patients with diabetes and without diabetes were matched for clinical presentation (diabetic patients, 45% asymptomatic; nondiabetic patients, 43%) and internal carotid artery percent stenosis (86.6% +/- 10.6% vs 86.4% +/- 10.6%). Patients with diabetes were younger at presentation than patients without (68.8 +/- 8.5 years vs 70.9 +/- 8.5 years; p < 0.005) and were more likely to have a history of coronary artery disease (53% vs 45%; p = 0.04). The mean total length of stay was 6.1 days for patients with diabetes and 4.8 days among patients without (p = 0.01). An adverse postoperative cardiac event (myocardial infarction, congestive heart failure, or arrhythmia) occurred in nine patients with diabetes (3.2%) and in five nondiabetic patients (1.1%; p < 0.05). By logistic regression analysis, however, diabetes was not an independent risk factor for a postoperative cardiac event (p = 0.28). There were 11 perioperative neurologic events (eight cerebrovascular accidents, three transient ischemic attacks) during the entire period (1.5%), of which six were among diabetic patients (2.1%) and five among nondiabetic patients (1.1%; p = NS). Of the eight cerebrovascular accidents, three occurred in diabetic patients (1.0%) and five in nondiabetic patients (1.1%; p = NS). The total operative mortality rate was 0.3% (diabetic patients, 1 of 284, 0.35%; nondiabetic, 1 of 447, 0.2%). CONCLUSIONS Patients with diabetes who undergo carotid endarterectomy are more likely to have coexisting cardiac disease, which may contribute to a higher incidence of postoperative cardiac morbidity. Diabetes mellitus alone, however, is not a risk factor for postoperative cardiac morbidity in patients who undergo carotid surgery. In addition, carotid endarterectomy may be safely performed in patients with diabetes with neurologic morbidity and mortality rates that are comparable with those of the nondiabetic population

The impact of diabetes on arterial reconstructions for multilevel arterial occlusive disease

PURPOSE Critical limb ischemia due to multilevel arterial occlusive disease often may be treated with an inflow procedure alone; however, a subset patients require a subsequent infrainguinal revascularization for persistence of their symptoms. As diabetic patients typically exhibit a pattern of extensive distal arterial disease, we sought to determine if the presence of diabetes mellitus altered the need for an outflow procedure after inflow bypass. METHODS A total of 504 patients undergoing inflow bypass for occlusive disease and lower extremity ischemia between 1990 and 1998 were entered prospectively into a computerized vascular registry. Inflow bypass procedures performed were as follows: aortofemoral (370; 73%), axillofemoral (56; 11%), femorofemoral (81; 16%). Of these patients, 79 required subsequent outflow bypass for unresolved ischemic symptoms. Multiple logistic regression analysis was used to analyze the effects of diabetes and multiple other risk factors on the need for an additional outflow procedure. RESULTS The indications for surgery were limb salvage (78%) and disabling claudication (22%). Overall morbidity was 17.7% (hematoma, 3.8%; wound infection, 2.5%; graft occlusion, 1.3%; myocardial infarction, 2.5%; acute renal failure,1.3%; pulmonary failure, 2.5%; pneumonia, 3.8%). Overall mortality was 0%. Diabetic patients comprised a greater proportion of the total number of patients requiring inflow bypass (301 of 504) as well as a greater proportion of patients requiring inflow and outflow procedures (47 of 79). Diabetes was determined not to be an independent risk factor for the need for multiple revascularization procedures by multiple logistic regression analysis (P >0.10). CONCLUSION Although patients with diabetes are predisposed to the development of distal arterial occlusive disease, in this study the subgroup of diabetic patients who present with aortoiliac occlusive disease were no more likely than patients without diabetes to require multiple levels of revascularization. These findings provide little rationale for simultaneous inflow and outflow procedures based on the presence of diabetes alone.

Is diabetes a risk factor for patients undergoing open abdominal aortic aneurysm repair

A number of studies have compared results after aortic procedures in diabetics vs nondiabetics but few have focused specifically on abdominal aortic aneurysm surgery. An analysis of prospective data was carried out in the Vascular Surgery Registry (Beth Israel Deaconess Medical Center, Boston, MA) and identified 421 patients (422 grafts) who underwent elective open repair of an abdominal aortic aneurysm between 1990 and 1999. The influence of diabetes mellitus on outcome was assessed by dividing the patients into two groups: 52 diabetic and 370 nondiabetic patients. Postoperative mortality was 1.7% overall (n =7) and proportionally higher in the diabetic population, although this did not reach statistical significance (3.8% vs 1.4%, p = 0. 19). However, cumulative survival at 1 year and 3 years was essentially identical for diabetic vs nondiabetic patients (91.0% vs 92.6% and 70.0% vs 73.5%, respectively) and did not diverge until 5 years after surgery (25.0% vs 50.9% respectively [p>0.05]). Overall, major complications occurred in 1 1 diabetics (21.2%) vs 58 nondiabetics (15.7%, p = 0.32). Specific complications that were increased in the diabetic population included pancreatitis (5.8% vs 1.1%, p = 0.01) and pneumonia (1 1.5% vs 3.2%, p = 0.006). Notably, overall cardiac morbidity was not higher in patients with diabetes mellitus (1.9% vs 4.3%, p = 0.41). Our data suggest that after elective open abdominal aortic aneurysm repair, patients with diabetes mellitus may have a higher rate of certain complications when compared to patients without diabetes mellitus. These differences however, do not preclude the expectation of excellent results of open abdominal aortic aneurysm repair in patients with diabetes mellitus.

Bypasses to tibial vessels using polytetrafluoroethylene as the solo conduit in a predominantly diabetic population.

The authors reviewed the Vascular Surgery Registry at the Beth Israel Deaconess Medical Center between 1990 and 1996 and identified 45 patients (47 limbs) who underwent bypass with polytetrafluoroethylene alone to infra-popliteal vessels. This represented only 2.6% of total tibial bypasses performed during that time. Sixty-nine percent of patients had diabetes. Indication for bypass was limb salvage in 96% of patients. Primary and secondary patency rates at 30 days, 1, 3, and 5 years were 87%, 87%; 58%, 60%; 41%, 43%; and 36%, 39%; respectively. Limb salvage rates at 30 days, 1, 3, and 5 years were 91%, 68%, 63%, and 63%. Cumulative survival rates at 3 and 5 years, however, were 53%, and 42%. The 29 grafts (64%) that were postoperatively anticoagulated with sodium warfarin showed trends in improved primary patency (47% vs 19%, p = 0.07), secondary patency (49% vs 20%, p = 0.03), and limb salvage (67% vs 58%, p = 0.06), at 3 years. There were no significant differences between diabetics and non-diabetics except in a trend toward decreased patient survival at 3 and 5 years in the diabetic population. Postoperatively, there were no deaths but there were two (4.2%) major cardiac complications. These data support the judicious use of tibial vessel bypass using PTFE in selected patients for limb salvage when autologous vein is not available. Diabetic patients appear to have similar results to non-diabetics and the postoperative use of sodium warfarin is beneficial.

Femoral Profunda Artery Aneurysm as an Unusual First Presentation of Behcet Disease

Behcet disease is a multisystem inflammatory disorder, rarely found in African Americans. Arterial involvement occurs in less than 8% of patients. Profunda femoral artery aneurysms (PFAAs) are extremely rare and often occur with synchronous aneurysms. We present a case of an African American man diagnosed with Behcet disease from his presentation with PFAA. He was also found to have a synchronous hypogastric artery aneurysm. The patient was immediately treated with corticosteroids and infliximab to control systemic and vascular inflammation, returning 1 month later for surgery. He had a repair of the left PFAA with a common femoral to profunda femoris artery bypass with reversed saphenous vein graft and aneurysmorrhaphy. When a patient presents with an aneurysm in an unusual location, it is important to evaluate for other aneurysms. A careful history and physical examination is also required to see if the aneurysm may be part of an underlying systemic syndrome.

The Impact of Micro-and Macrovascular Disease on Diabetic Neuropathy and Foot Problems

Diabetes mellitus is found in as many as 13 million people nationally, or 5.2% of the United States population, and more than 650,000 new cases are diagnosed annually (1). Many of the clinical complications of diabetes may be ascribed to alterations in vascular structure and function, with subsequent end-organ damage and death. Specifically, two types of vascular disease are seen in patients with diabetes: a nonocclusive microcirculatory impairment involving the capillaries and arterioles of the kidneys, retina, and peripheral nerves, and a macroangiopathy characterized by atherosclerotic lesions of the coronary and peripheral arterial circulation (2–5). The former is relatively unique to diabetes, whereas the latter lesions are morphologically similar in both nondiabetic and diabetic patients.

Microvascular Changes in the Diabetic Foot

Problems of the diabetic foot are the most common cause for hospitalization in diabetic patients, with an annual health care cost of over