Stephen G. Lalka

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.

Dobutamine stress echocardiography for assessment of cardiac risk before noncardiac surgery

Abstract Two-dimensional echocardiography performed during incremental infusion of dobutamine has been shown to be a safe and accurate method for detection of coronary artery disease in patients who are unable to undergo conventional exercise testing. 1,2 A significant proportion of these patients are referred for evaluation before undergoing noncardiac surgery, such as abdominal aortic aneurysm resection, lower extremity revascularization procedures and hip replacement. Little is known about the value of dobutamine stress echocardiography for assessment of preoperative cardiac risk. This portable and relatively low cost technique provides rapid results and, thus, has potential advantages over alternative technologies, such as dipyridamole thallium scintigraphy, which have established prognostic value. 3–5 This retrospective study reports on the results of dobutamine stress echocardiography performed for preoperative cardiac risk assessment.

Long-term results after inferior vena caval resection during retroperitoneal lymphadenectomy for metastatic germ cell cancer

PURPOSE The long-term sequelae of inferior vena caval (IVC) resection during retroperitoneal lymph node dissection for metastatic nonseminomatous germ cell testis tumor (NSGCT) were assessed. METHODS Between December 1973 and September 1996, 2126 of our patients underwent RPLND for retroperitoneal nodal metastases from NSGCT; 955 had bulky disease (stages B2, B3, or C) after cytoreduction chemotherapy. Of this latter group, 65 patients (6.8%) required infrarenal IVC resection during tumor excision for cure. Our protocol does not include IVC reconstruction in such cases. Indications for IVC resection included tumor encasement or encroachment, postchemotherapy desmoplastic compression, or thrombus with tumor or clot in which cavotomy and thrombectomy cannot be performed. RESULTS Twenty-four of the 65 patients (postoperative follow-up period range, 11 months to 16 years; median, 89 months) were alive and able to be examined or interviewed by written and/or phone survey to assess the long-term morbidity of their IVC resection. Based on the 1994 American Venous Forum International Consensus Committee reporting standards, the clinical classifications of these 24 patients were C0A (4), C3S (4), C4A (2), C4S (13), and C6A (1). Long-term disability was mild or absent in 75% of these patients. CONCLUSION Only 1 (4.2%) of the patients surveyed had chronic venous sequelae that would fulfill the accepted criteria for subsequent elective IVC reconstruction. Despite recent reports of IVC reconstruction demonstrating relatively good patency rates and low morbidity, the addition of such a complex, time-consuming procedure to extensive retroperitoneal lymph node dissection for metastatic NSGCT involving IVC resection is generally not necessary.

Prospective comparison of noninvasive techniques for amputation level selection

This study prospectively compared the following tests for their accuracy in amputation level selection: transcutaneous oxygen, transcutaneous carbon dioxide, transcutaneous oxygen-to-transcutaneous carbon dioxide, foot-to-chest transcutaneous oxygen, intradermal xenon-133, ankle-brachial index, and absolute popliteal artery Doppler systolic pressure. All metabolic parameters had a high degree of statistical accuracy in predicting amputation healing whereas none of the other tests had statistical reliability. Amputation site healing was not affected by the presence of diabetes mellitus nor were the test results for any of the metabolic parameters.

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.

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.