Dolores F. Cikrit

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.

Comparative effects of Indomethacin, Prostaglandin E1, and Ibuprofen on bowel ischemia

This study evaluates the effects of Indomethacin (IND), Prostaglandin E1 (PGE1), and Ibuprofen (IBP) in a bowel ischemia model. Laparotomy was performed in 80-gram rats (n = 260). Transient ischemia was induced by a one minute occlusion of the superior mesenteric artery. Animals were placed in five experimental groups: (I) ischemic controls (n = 80), (II) PGE1, 80 micrograms/kg IV (n = 20), (III) IBP, 12.5 mg/kg IV (n = 60), (IV) IND 15 mg/kg IV (n = 80) and (V) PGE1 + IND (n = 20). All medications were given just prior to laparotomy. Animals were evaluated for survival, length of survival and the presence of bowel necrosis and/or perforation at seven days. Survival was 18% in controls and was reduced to 5% by IND (p less than .005). Improved survival was observed with PGE1 (35%), TBP (31%) and PGE1 + IND (35%). IND resulted in early death, while PGE1, IBP, and PGE1 + IND all increased the length of survival (p less than .05). IND-treated rats had a high incidence of bowel perforation (greater than 40%). PGE1 reversed this effect when given concomitantly with IND. IBP had a significantly lower incidence of intestinal necrosis. These data suggest that infants treated with IND who are at risk for NEC should be carefully monitored for evidence of bowel necrosis. PGE1 and IBP may have a cytoprotective role in subjects at risk for bowel ischemia.

Acetazolamide enhanced single photon emission computed tomography (SPECT) evaluation of cerebral perfusion before and after carotid endarterectomy

Twenty-five patients were tested before and after carotid endarterectomy with resting and acetazolamide enhanced single photon emission computed tomography (SPECT) scans with hexamethyl propyleneamine oxine (HMPAO) or iofetamine hydrochloride I123 (123I labeled IMP), both widely available radiopharmaceuticals. Twenty preoperative SPECT studies were asymmetric, revealing focal or diffuse decreased perfusion reserve, and 13 also demonstrated infarcts. Five patients had symmetric (normal) studies. After carotid endarterectomy, 22 cases had changed flow distribution patterns. Usually improvement of reactivity ipsilateral occurred to the area operated on. In four, contralateral improvement was also found. Three of the patients who had preoperative symmetrical scans had increased ipsilateral reactivity after surgery indicating previous global loss of reactivity. Acetazolamide SPECT scans demonstrate a decreased perfusion reserve in 20 patients with carotid artery stenosis, indicating reduced perfusion and poor collateral circulation. Postoperative studies confirm improvement by demonstrating recovery of vascular reactivity in 84% of the patients. Acetazolamide enhanced SPECT scans may be helpful in providing objective evidence for selection of patients for carotid endarterectomy, especially in those who have an 80% carotid artery stenosis, but are asymptomatic.

Interpretations and Treatment Decisions Based on MR Angiography versus Conventional Arteriography in Symptomatic Lower Extremity Ischemia

PURPOSE To determine the frequency with which treatment plans based on findings at magnetic resonance angiography (MRA) match those based on findings at conventional x-ray arteriography (XRA) in the evaluation of symptomatic lower extremity ischemia. PATIENTS AND METHODS Two-dimensional time-of-flight (TOF) MRA was performed in 42 patients undergoing XRA for evaluation of symptomatic lower extremity ischemia. The blind interpretations and treatment plans based on MRA findings were compared with those based on XRA findings, with use of XRA as the standard of reference. RESULTS For identification of hemodynamically significant stenosis or occlusion, the sensitivity and specificity of MRA was 100% and 23% for iliac segments, 100% and 82% for common femoral segments, 89% and 67% for superficial femoral segments, 100% and 88% for popliteal segments, and 92% and 91% for tibioperoneal segments, respectively. The treatment plan based on MRA findings matched that based on XRA findings in 41% of patients. CONCLUSION For evaluation of symptomatic lower extremity ischemia, two-dimensional TOF MRA cannot be considered a reliable substitute for XRA in patients who lack contraindications to XRA.

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.

Acellular vascular matrix: A natural endothelial cell substrate

A preliminary assessment was made of the acellular vascular matrix graft as a substrate for endothelial cell seeding, with respect to surface pretreatment (none versus fibronectin and/or serum) and presence of exogenous growth factor. Arteries were harvested from greyhounds and exposed to a sequential detergent extraction process to produce the acellular vascular matrix. Human umbilical vein endothelial cells were grown in tissue culture, harvested in first passage, then seeded at 10(5) cells/cm2 on sections of acellular vascular matrix and on gel-coated polystyrene positive controls. After 18 hour incubation, endothelial cell-seeded acellular matrices were fixed and processed for histologic and planimetric analysis; control wells were fixed and endothelial cells were counted by planimetry. Pretreatment of the acellular vascular matrix was found to have no effect on the percentage of endothelial cell coverage of the matrix. There was significantly better endothelial cell coverage of the acellular matrix than on matched gel-treated polystyrene control wells. Withdrawal of growth factor resulted in a significant reduction in endothelial cell coverage for all acellular vascular matrix groups. Growth factor withdrawal also significantly reduced attachment of endothelial cells on gel-treated polystyrene. Cell surface area was significantly smaller when growth factor was withdrawn from all groups except from the acellular vascular matrix without pretreatment. We conclude that: (1) the acellular vascular matrix is conductive to endothelial cell adherence and spreading even without pretreatment; and (2) sudden withdrawal of exogenous growth factor may impair early coverage of substrates by endothelial cells due to an effect on their adherence or spreading.

Long-term follow-up of the Palmaz stent for iliac occlusive disease.

BACKGROUND Thirty-eight limbs with iliac occlusive disease were treated with Palmaz stents from 1987 through 1991. METHODS Indications for stent utilization included dissection induced by percutaneous transluminal balloon angioplasty (PTA) (10), restenosis after PTA (nine), post-PTA residual stenosis (nine), multiple stenoses or occlusion (five), and unfavorable location (five). RESULTS The ankle/brachial pressure index increased from 0.53 +/- 0.27 to 0.8 +/- 0.26 after stent deployment. The intraluminal pressure gradient decreased from 31.9 +/- 16.3 to 0.9 +/- 2.2 mm Hg after stent deployment. Complications included pseudoaneurysm (one), arteriovenous fistula (one), iliac perforation (one), groin hematoma (two), and occlusion (two). Follow-up arteriogram showed stenosis proximal or distal (n = 4) or within the stents (n = 4). These were treated with PTA or stents. Two patients required an aortobifemoral graft. Nine patients have died. Life table analysis showed a 1-, 3-, and 5-year primary and secondary cumulative patency of 87% +/- 5.9%, 74% +/- 8.2%, and 63% +/- 10% and 91% +/- 5.1%, 91% +/- 5.6%, and 86% +/- 7.6%, respectively. CONCLUSIONS Palmaz stents, often required to salvage a PTA failure, appear to maintain overall patency at a high level. However, intimal hyperplasia and the progression of atherosclerotic disease may result in a need for additional procedures to obtain this favorable 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.

Long-term follow-up after surgical management of necrotizing enterocolitis: Sixty-three cases

One hundred twenty-five infants underwent surgical intervention for necrotizing enterocolitis between 1972 and 1984. Sixty-three infants, who survived more than 30 days postoperatively, were evaluated for long-term complications. There were 28 girls and 35 boys (mean birth weight 1,725 +/- 890 g; gestational age 32 +/- 4 weeks). Associated problems included hyaline membrane disease (43), cardiac anomalies (25), and trisomy 21(2). Thirty-six survivors required long-term ventilatory support. Fifty-nine infants underwent bowel resection and enterostomy, 3 decompressing enterostomies without resection, and 1, exploratory laparotomy only. Enterostomies were closed at four months. Twenty four had short bowel syndrome. Fifteen infants subsequently died for a late mortality rate of 23%. Mortality was related to sepsis (3), respiratory failure (5), cardiac anomalies (3), cardio-respiratory arrest (2), and TPN related liver failure (2), and was common with gestational age less than 31 weeks and birth weight less than 1,000 g. Medical problems included cholestasis (17), TPN induced cirrhosis (3), meningitis (3), seizures (8), and nutritional rickets (6). Significant developmental and intellectual delays were observed.