Arnold Miller

In vivo Raman spectral pathology of human atherosclerosis and vulnerable plaque.

The rupture of vulnerable atherosclerotic plaque accounts for the majority of clinically significant acute cardiovascular events. Because stability of these culprit lesions is directly related to chemical and morphological composition, Raman spectroscopy may be a useful technique for their study. Recent developments in optical fiber probe technology have allowed for the real-time in vivo Raman spectroscopic characterization of human atherosclerotic plaque demonstrated in this work. We spectroscopically examine 74 sites during carotid endarterectomy and femoral artery bypass surgeries. Of these, 34 are surgically biopsied and examined histologically. Excellent signal-to-noise ratio spectra are obtained in only 1 s and fit with an established model, demonstrating accurate tissue characterization. We also report the first evidence that Raman spectroscopy has the potential to identify vulnerable plaque, achieving a sensitivity and specificity of 79 and 85%, respectively. These initial findings indicate that Raman spectroscopy has the potential to be a clinically relevant diagnostic tool for studying cardiovascular disease.

Efficacy of the dorsal pedal bypass for limb salvage in diabetic patients: Short-term observations

Limbs of diabetic patients with distal tibial disease are frequently considered unreconstructible; however, when studied with intraarterial digital subtraction angiography, the dorsal pedal artery is frequently found to be patent. We have reviewed our recent experience with 96 patients, 94% of whom had diabetes and had 97 bypasses placed to the dorsal pedal artery. All procedures were for limb salvage. Superimposed infection was present in 42.3%. In 92 instances where intraarterial digital subtraction angiography successfully visualized the dorsal pedal artery, 91 bypasses were placed. In 12 other cases where the dorsal pedal artery was not visualized by intraarterial digital subtraction angiography but audible with the continuous-wave Doppler, bypasses were completed successfully in six. All procedures were performed with vein. Inflow was taken from the femoral artery in 48, popliteal artery in 45, tibial artery in 2, and from a femoral tibial graft in 2. Perioperative mortality was 1.92%. Actuarial graft patency, limb salvage, and patient survival were 82%, 87%, and 80%, respectively at 18 months. We conclude that bypass grafting to the dorsal pedal artery can be reliably performed with acceptable short-term results. An attempt should always be made to visualize the foot vessels angiographically, especially in diabetic patients, so that this valuable option in arterial reconstruction will not be overlooked.

Safety of vein bypass grafting to the dorsal pedal artery in diabetic patients with foot infections

The results of 56 vein bypasses to the dorsal pedal artery performed in 53 diabetic patients who were admitted with ischemic foot lesions complicated by infection were reviewed. All patients had one or more of the following: infected ulcers (73%), cellulitis (45%), osteomyelitis (29%), gangrene (20%), or abscess (2%). Organisms were cultured from 84% of patients (average 2.6, range 1 to 9 organisms per infection). Elevated temperature (greater than 37.7 degrees C) or leukocytosis (greater than 9.0 x 10(3)/ml) were seen in 13% and 50% of patients, respectively. All patients were treated with broad-spectrum antibiotics, local debridement, wound care, and bed rest. Operative debridement or open partial forefoot amputation were required to control sepsis in 11 patients (20%). Treatment of infection delayed revascularization by an average of 10.7 days. All patients underwent autogenous vein bypasses to the dorsal pedal artery. Two grafts failed within 30 days (3.6%), and one patient died (1.8%). Wound infections developed in seven patients (12.5). One wound infection resulted in graft disruption and patient death at 2 months. Average length of stay of the initial hospitalization was 29.8 days. Fifty-two patients were discharged with patent grafts and salvaged limbs; however, 31 subsequent foot procedures and 35 rehospitalizations were required to ultimately achieve foot healing. Actuarial graft patency and limb salvage were 92% and 98%, respectively at 36 months. Pedal bypass to the ischemic infected foot is efficacious and safe as long as infection is adequately controlled first. The complexity of these situations often requires multiple surgical procedures and extensive wound care, resulting in prolonged or multiple hospitalizations.

Comparison of angioscopy and angiography for monitoring infrainguinal bypass vein grafts: Results of a prospective randomized trial

PURPOSE This study was designed to determine whether, in primary infrainguinal bypass grafts in which only saphenous vein is used as the graft conduit, routine monitoring with intraoperative angioscopy can improve early graft patency as compared with standard monitoring with intraoperative completion angiography; and to delineate the advantages and disadvantages of these two modalities and their respective roles for the routine monitoring of the infrainguinal bypass graft. METHODS A total of 293 patients undergoing primary saphenous vein infrainguinal bypass grafting were prospectively randomized and monitored with either completion angioscopy or completion angiography. Clinical parameters, indications for operation, graft anatomy, and configuration were evenly matched in both groups. Forty-three bypasses were excluded from the study after randomization, including 12 veins randomized to angiogram, deemed inferior, and prepared with angioscopy. RESULTS In the 250 bypass grafts (angioscopy 128, angiography 122) there were 39 interventions (conduit, 29; anastomosis, 8; distal artery, 2), 32 with angioscopy and 7 with angiography (p < 0.0001). Twelve (4.8%) of the 250 grafts failed in less than 30 days, four (3.1%) of 128 in the angioscopy group and eight (6.6%) of 122 in the angiography group (p = 0.11 by one-sided hypothesis test). CONCLUSION Although no statistical improvement in the proportions of failures in primary saphenous vein bypass grafts routinely monitored with completion angioscopy rather than the standard completion angiogram was demonstrated, the study delineates a trend that favors completion angioscopy for routine vein graft monitoring and demonstrates the advantages of angioscopy in preparing the optimal vein conduit.

Popliteal-to-distal bypass grafts for limb salvage in diabetics

Between January 1984 and August 1989, 117 diabetic patients with a palpable popliteal pulse but distal limb threatening ischaemia underwent 124 popliteal artery (or below) to distal bypass grafts. All grafts were intra-operatively monitored. The operative mortality was 0.8% and the 30 day primary patency 93%. Primary patencies at 1 and 3 years were 88.6 and 85.2%, respectively. The results of using the popliteal artery as the proximal graft inflow site in diabetes are comparable to other patient groups and to alternative more proximal inflow sites, but require a shorter length of vein graft with a shorter vein harvesting incision, avoid groin disection and result in a more peripheral operation.

Noninvasive vascular imaging in the diagnosis and treatment of adventitial cystic disease of the popliteal artery

This brief case report describes the successful outcome after surgical excision of multiple adventitial cysts of the popliteal artery in a 75-year-old man with rapidly worsening claudication. It highlights several unsettled points concerning the diagnosis, cause, and management of cystic adventitial disease of the popliteal artery and compares duplex ultrasound, computed tomography, and magnetic resonance angiography in the noninvasive diagnosis and treatment of this condition.

Arigioscopy of Arm Vein Infrainguinal Bypass Grafts

Between January 1988 and December 1990, 56 patients underwent 66 arm vein infrainguinal bypass grafts for limb salvage. Thirty-nine grafts were intraoperatively monitored by the standard methods of continuous wave Doppler alone (30) and arteriography (9). Twenty-seven grafts were prepared and monitored by intraoperative angioscopy. No significant findings requiring intraoperative revision or correction were noted in the grafts monitored by the standard methods. However, in those grafts prepared and monitored by angioscopy, intraluminal abnormalities of the arm veins were detected and corrected in 20/27 (74%). None of the grafts prepared or monitored by angioscopy occluded within 30 days, whereas, in those grafts monitored by continuous wave Doppler and arteriography, 7/39 failed within 30 days, a primary patency rate of 32/39 (82%) (x2 with Yates correction, p=0.055). This study shows that angioscopic preparation and monitoring of arm vein bypass grafts allows the detection and correction of unsuspected intraluminal abnormalities, which appears to improve the early primary patency of arm vein infrainguinal bypass grafts.

Correlation of spectral phonoangiography and carotid angiography with gross pathology in carotid stenosis.

Spectral phonoangiography, a noninvasive method for measurement of the residual-lumen diameter of carotid stenosis by bruit analysis, was compared with x-ray angiography and direct measurement of the pathological specimen at carotid endarterectomy in 39 bifurcations from 36 patients. In six studies, the bruit was too faint to analyze. In 31 of the other 33 studies, the phonoangiogram predicted the residual-lumen diameter to within 0.5 mm of the measured value. Of the 39 contrast angiograms, 35 showed residual lumens within 0.5 mm of the value measured in the specimen, two showed lumens between 0.5 and 1 mm, and the sizes of two could not be estimated because of vessel overlap in all planes. Spectral phonoangiography and contrast angiography are both accurate methods for evaluation of carotid stenosis. Since phonoangiography is noninvasive, it may be of particular value in determining the natural history in patients with carotid bruits.

A multicenter study of permanent hemodialysis access patency: beneficial effect of clipped vascular anastomotic technique

OBJECTIVE There is an urgent and compelling need to reduce the morbidity and expense of maintaining hemodialysis vascular access patency. This large, long-term, retrospective, multicenter study, which compared access patency of autogenous arteriovenous fistulas (AVF) and synthetic bridge grafts (AVG) created with conventional sutures or nonpenetrating clips, was undertaken to resolve conflicting results from previous smaller studies. DESIGN Patency data for 1385 vascular access anastomoses (clipped or sutured) was obtained from 17 hospitals and dialysis centers (Appendix). Five hundred eighteen AVF (242 clip, 276 suture) and 827 AVG (440 clip, 384 suture) were analyzed. Statistical comparisons were made with Kaplan-Meier survival analysis, log-rank test, two-sample t test, and X(2) test. The Cox proportional hazards model was used to confirm Kaplan-Meier analysis. RESULTS Access patency (primary, secondary, overall, and intention to treat) was significantly improved in access anastomoses constructed with clips. In the intention-to-treat group, primary patency at 24 months was 0.54 for clipped AVF and 0.34 for sutured AVF, and was 0.36 for clipped AVG and 0.17 for sutured AVG. At 24 months, primary patency rate for AVF successfully used for dialysis was 0.67 for clips and 0.48 for sutures, and for AVG was 0.39 for clips and 0.19 for sutured constructs. Interventions necessary to maintain patency were significantly fewer in clipped anastomoses. CONCLUSION Replacing conventional suture with clips significantly reduces morbidity associated with maintaining permanent hemodialysis vascular access. This beneficial effect may be due to the biologic superiority of interrupted, nonpenetrating vascular anastomoses.

Multimodal spectroscopy detects features of vulnerable atherosclerotic plaque

Early detection and treatment of rupture-prone vulnerable atherosclerotic plaques is critical to reducing patient mortality associated with cardiovascular disease. The combination of reflectance, fluorescence, and Raman spectroscopy-termed multimodal spectroscopy (MMS)-provides detailed biochemical information about tissue and can detect vulnerable plaque features: thin fibrous cap (TFC), necrotic core (NC), superficial foam cells (SFC), and thrombus. Ex vivo MMS spectra are collected from 12 patients that underwent carotid endarterectomy or femoral bypass surgery. Data are collected by means of a unitary MMS optical fiber probe and a portable clinical instrument. Blinded histopathological analysis is used to assess the vulnerability of each spectrally evaluated artery lesion. Modeling of the ex vivo MMS spectra produce objective parameters that correlate with the presence of vulnerable plaque features: TFC with fluorescence parameters indicative of collagen presence; NC∕SFC with a combination of diffuse reflectance β-carotene∕ceroid absorption and the Raman spectral signature of lipids; and thrombus with its Raman signature. Using these parameters, suspected vulnerable plaques can be detected with a sensitivity of 96% and specificity of 72%. These encouraging results warrant the continued development of MMS as a catheter-based clinical diagnostic technique for early detection of vulnerable plaques.