Michael C. Dalsing

Dobutamine stress echocardiography as a predictor of cardiac events associated with aortic surgery

Two-dimensional echocardiography can detect regional wall motion abnormalities resulting from myocardial ischemia produced by dobutamine infusion. In 60 patients undergoing elective aortic surgery (27 with aneurysms, 33 with occlusive disease), we evaluated the ability of dobutamine stress echocardiography to predict perioperative cardiac events. Echo images were obtained at rest and during incremental dobutamine infusion to a peak dose of 50 micrograms/kg/min, unless another test end point was reached (angina, heart rate greater than or equal to 85% of age-predicted maximum, significant ST segment depression, or new stress-induced wall motion abnormalities). Dobutamine stress echocardiography results were stratified as follows: group I, no wall motion abnormalities; group II, resting wall motion abnormalities unchanged with stress; group III, stress-induced worsening of resting wall motion abnormalities; group IV, new-onset wall motion abnormalities with stress. Twelve cardiac events occurred within the first 30 postoperative days: three cardiac deaths (5%), six nonfatal myocardial infarctions (10%), two patients with unstable angina (3.3%), and one patient with asymptomatic elevation of creatine phosphokinase MB isoenzymes without electrocardiographic changes (1.7%). Eleven events occurred in the 38 patients with an abnormal dobutamine stress echocardiograph (groups II to IV); in contrast, only one of 22 patients with a normal dobutamine stress echocardiograph (group I) had a cardiac event. These event rates (29% vs 4.6%) differed significantly (p less than 0.025). Dobutamine stress echocardiography is a new, safe, rapid, relatively low cost, noninvasive, nonexercise cardiac stress test for risk stratification before major vascular surgery.

Signs and symptoms of saphenous nerve injury after greater saphenous vein stripping: prevalence, severity, and relevance for modern practice

PURPOSE Saphenous nerve injury has long been recognized as a risk of greater saphenous vein stripping, and it has been suggested by some authors as a reason to avoid stripping below the knee. The rate of injury reported in the literature is extremely variable, with no study adequately addressing the effect of these injuries on patient quality of life. We undertook this study to measure the prevalence of these injuries and quantify their impact on quality of life. METHODS A cross-sectional study of patients who had undergone primary greater saphenous vein stripping to the ankle was performed. Patients who had undergone this procedure, performed in a downward manner by a single surgeon over a 12-year period, were contacted and asked to return for a follow-up examination. Subjects completed the Aberdeen Varicose Vein Symptom Severity Score as well as a questionnaire designed to identify symptoms of saphenous nerve injury and any effects on quality of life. They were then evaluated for saphenous nerve deficits with simple neurologic tests. Charts were reviewed to determine preoperative CEAP classification. Results were analyzed for statistically significant differences between groups. RESULTS Out of 111 patients (127 legs) who had undergone the procedure, 38 (34%) agreed to participate in the study. Three of these patients were ultimately excluded because of an inability to obtain a reliable neurologic examination of the legs, leaving 35 patients with a total of 45 legs operated. Participants did not differ from the potential study population in demographic data, follow-up interval, or preoperative CEAP classification. Median time since operation was 4.5 years (range, 8 months to 10.75 years). Overall, 40% of patients reported symptoms consistent with saphenous nerve injury at some time after operation, but these symptoms affected quality of life in only 6.7%. Symptoms persisted at evaluation in 17.8%, and only one patient (2.3%) reported any negative effect on quality of life at the time of examination. Saphenous nerve deficits were identified in 58% of patients. Patients with deficits had no statistically significant differences from those without deficits in terms of demographic data, follow-up interval, preoperative CEAP class, or Aberdeen score. CONCLUSIONS Signs and symptoms of saphenous nerve injury are common at long-term follow-up after greater saphenous vein stripping to the ankle. However, there appears to be little, if any, significant resultant morbidity. The risk of saphenous nerve injury should therefore not be considered a reason to avoid stripping of the greater saphenous vein to the ankle.

A prospective, in vivo study of the relationship between blood flow hemodynamics and atherosclerosis in a hyperlipidemic swine model

PURPOSE This is the first prospective evaluation of the relationship between shear stress and atherosclerotic plaque formation in a pulsatile, in vivo model. METHODS A 50% aortic stenosis was created in six Yucatan micropigs by placing a suture line across the left half of the aorta. A specially modified 20 MHz Doppler ultrasound probe mounted at a 45 degree angle on a micromanipulator was used to measure blood flow velocity along the lateral aspects of the aorta. Shear stress at these locations was calculated with linear regression. The pigs were then fed a specially formulated hyperlipidemic diet for 7 months, after which their aortas were harvested. Plaque thickness was measured and correlated with mean, maximum, and minimum shear stress at each site and side on or away from the aortic plication and distance from the level of the aortic plication with general linear modeling. RESULTS Plaque thickness was negatively correlated with the mean shear stress during the cardiac cycle (correlation coefficient -0.3972 p = 0.0164) and with the maximum shear stress during the cardiac cycle (correlation coefficient -0.4581 p = 0.0050). Plaque thickness was correlated with a multivariate model of mean shear stress, maximum shear stress, and their interactive effects with other parameters in the model with a correlation coefficient of 0.6733, (p = 0.0048). CONCLUSIONS This is the first prospective, in vivo study with a pulsatile, hyperlipidemic model, which clearly demonstrates that low shear stress is associated with plaque formation.

Cerebral vascular reactivity assessed with acetazolamide single photon emission computer tomography scans before and after carotid endarterectomy

BACKGROUND AND METHODS In 64 patients, cerebral perfusion and vascular reactivity were assessed before and after carotid endarterectomy (CEA) using acetazolamide (ACZ)-enhanced single photon emission computer tomography (SPECT). Twenty-five patients were asymptomatic, whereas the remainder were symptomatic. Sixty-one patients had a > or = 70% ipsilateral internal carotid artery stenosis. RESULTS Fifty SPECT scans revealed decreased vascular reactivity. Twenty-three showed infarcts. Fourteen patients had normal studies. Twenty of the SPECT scans of asymptomatic patients demonstrated poor vascular reactivity. After CEA, 39 patients had improved ipsilateral vasoreactivity. In 12 patients, contralateral improvement was also found. CONCLUSION ACZ-enhanced SPECT scans, by assessing cerebral perfusion and vascular reactivity, may help to identify patients at risk of stroke should perfusion further diminish. Postoperative studies confirm improvement in vascular reactivity. ACZ-enhanced SPECT scans may provide objective evidence for the selection of patients with a high-grade asymptomatic carotid stenosis for CEA.

Aggressive management of vascular injuries of the thoracic outlet

PURPOSE We present a review of 35 patients who underwent an operation for subclavian (n = 18) or axillary (n = 17) vessel injury. In some patients, both an artery and a vein were damaged, resulting in a total of 30 arterial and 16 venous injuries. METHODS The wounding source included a gunshot (n = 19), a stab wound (n = 9,) and blunt trauma (n = 7). Seven patients had hypotension and were taken immediately to the operating room. Seventeen patients had diminished or absent pulses, whereas 13 patients had normal pulses despite an arterial injury. Associated injuries included nerve injury (n = 15), pneumohemothorax (n = 5), and fractures (n = 7). Angiography in 21 patients demonstrated an intimal flap (n = 8), extravasation (n = 5), a pseudoaneurysm (n = 3), an arteriovenous fistula (n = 2), and occlusion (n = 1). Two angiograms were normal. Arterial repair was accomplished by interposition graft (n = 17), primary repair (n = 9), patch angioplasty (n = 3,) and ligation (n = 1). RESULTS No functional deficits occurred in patients with an isolated vascular injury. Seven patients with associated brachial plexus injuries experienced severe disability. One arm of a patient was amputated. Two patients died. CONCLUSIONS The use of angiography helps to confirm and localize injuries. Prompt correction of the vascular injury avoids disability resulting from ischemia. Although the amputation rate is low with vascular repair, the functional disability resulting from associated nerve injuries can be devastating.

Stent grafting of abdominal aortic aneurysms: pre-and postoperative evaluation with multislice helical CT.

Endovascular stent grafting of abdominal aortic aneurysms is a new technique that may replace open surgery in selected cases. Pre-and postoperative angiography can be replaced by helical CT. This pictorial essay describes and illustrates the use of multislice helical CT where maximum intensity projection and multiplanar reformats play a central role in the evaluation.

Recommended Reporting Standards for Endovenous Ablation for the Treatment of Venous Insufficiency: Joint Statement of the American Venous Forum and the Society of Interventional Radiology

Sanjoy Kundu, MD, FRCPC, FCIRSE, FASA, Fedor Lurie, MD, Steven F. Millward, MD, FRCPC, FSIR, Frank Padberg Jr, MD, Suresh Vedantham, MD, Steven Elias, MD, Neil M. Khilnani, MD, William Marston, MD, John F. Cardella, MD, FSIR, FACR, Mark H. Meissner, MD, Michael C. Dalsing, MD, Timothy W.I. Clark, MD, FSIR, and Robert J. Min, MD, MBA, FSIR, Toronto and Peterborough, Ontario, Canada; Honolulu, Hawaii; Newark and Englewood, NJ; Saint Louis, Mo; New York, NY; Chapel Hill, NC; Springfield, Mass; Seattle, Wash; and Indianapolis, Ind

A multicenter, phase I evaluation of cryopreserved venous valve allografts for the treatment of chronic deep venous insufficiency

PURPOSE A phase I feasibility study was conducted to determine whether cryopreserved venous valved segments would remain patent/competent in a short-term period (6 months). METHODS The target group consisted of 10 patients (C(4-6), E, A(D), P(R)). The exclusion criteria included untreated superficial/perforator venous disease, significant venous or arterial obstruction, hypercoagulability or coagulopathy, and significant preexisting medical conditions. Required preoperative tests were venous duplex, ascending/descending venography, and a physiologic study (eg, APG, blood typing, an ankle/brachial index, and if post-thrombotic, a hypercoagulability work-up). A single-valve transplant was placed below all reflux, aided by anticoagulation with or without a distal arteriovenous fistula. Postoperative assessment included duplex scanning/clinical examination (at 1, 3, and 6 months), descending venogram (at 1 month), and physiologic study (at 1 and 6 months). The primary end point was valve patency/competence, with clinical outcome as a secondary end point. Adverse events were recorded. RESULTS After eliminating protocol violations, nine patients with superficial femoral (5) or popliteal (4) vein valve transplants were studied. Six-month actuarial results show a patency rate of 67% +/- 16% and 78% +/- 13%, respectively, a primary and secondary competency rate of 56% +/- 17% and 67% +/- 16%, respectively, and a 100% patient survival rate. Clinical outcome averaged 1.1, with healing and/or freedom from ulcer recurrence, in six of nine patients. A postoperative risk of seroma formation (3) and cellulitis (1) exists. CONCLUSION In patients with few remaining therapeutic options, one can achieve a 6-month assisted patency and competency rate of 78% and 67%, respectively, with an improved clinical outcome.

An experience with upper-extremity vascular trauma.

In this 6-year study of 101 limbs requiring surgical intervention for upper-extremity vascular trauma, most patients were male, young, and injured by penetrating objects. Injured vessels included 13 axillary/subclavian, 23 brachial, 40 radial, and 25 ulnar arteries. Concomitant injuries included nerve injury in 50 cases, tendon laceration in 29, and bony fracture in 11. Arterial repair was accomplished by primary repair in 54 limbs, vein graft in 26 limbs, and vein patch in 3 limbs. Seventeen arterial injuries were ligated. Ancillary procedures included 30 nerve or 27 tendon repairs. The limb salvage rate was 99%. No functional deficits were noted in those cases with only a vascular injury. In 64% and 25% of patients with nerve or musculoskeletal injury, respectively, the arm was functionally impaired. Prompt diagnosis and surgical intervention eliminate vascular injury as a factor in upper-extremity limb loss or disability. Functional deficits are the result of nerve or orthopedic injuries.

Suppressed hindlimb perfusion in Rac2−/− and Nox2−/− mice does not result from impaired collateral growth

While tissue perfusion and angiogenesis subsequent to acute femoral artery occlusion are suppressed in NADPH oxidase 2 (Nox2)-null (Nox2(-/-)) mice, studies have not established the role of Nox2 in collateral artery enlargement. Rac2 is a small GTPase that binds Nox2 and activates Nox2-based NAD(P)H oxidase but, unlike Nox2, is primarily restricted to bone marrow-derived cells. In this study, we used Rac2-null (Rac2(-/-)) and Nox2(-/-) mice with a novel method of identifying primary hindlimb collaterals to investigate the hypothesis that collateral growth requires these molecules. When initial experiments performed with femoral ligation demonstrated similar perfusion and collateral growth in Rac2(-/-) and wild-type C57BL/6J (BL6) mice, subsequent experiments were performed with a more severe ischemia model, femoral artery excision. After femoral excision, tissue perfusion was suppressed in Rac2(-/-) mice relative to BL6 mice. Histological assessment of ischemic injury including necrotic and regenerated muscle fibers and lipid and collagen deposition demonstrated greater injury in Rac2(-/-) mice. The diameters of primary collaterals identified during Microfil injection with intravital microscopy were enlarged to a similar extent in BL6 and Rac2(-/-) mice. Intimal cells in collateral cross sections were increased in number in both strains and were CD31 positive and CD45 negative. Circulating leukocytes and CD11b(+) cells were increased more in Rac2(-/-) than BL6 animals. Experiments performed in Nox2(-/-) mice to verify that the unexpected results related to collateral growth were not unique to Rac2(-/-) mice gave equivalent results. The data demonstrate that, subsequent to acute femoral artery excision, perfusion recovery is impaired in Rac2(-/-) and Nox2(-/-) mice but that collateral luminal expansion and intimal cell recruitment/proliferation are normal. These novel results indicate that collateral luminal expansion and intimal cell recruitment/proliferation are not mediated by Rac2 and Nox2.