Biomedical subjects

T H Schwarcz

Publications and source records attributed to T H Schwarcz.

At least 19 recordsLinked to original sources

PubMed2001

Enoxaparin treatment in high-risk trauma patients limits the utility of surveillance venous duplex scanning.

OBJECTIVE: The value of surveillance venous duplex scanning for detecting unsuspected deep venous thrombosis (DVT) in trauma patients who are receiving enoxaparin prophylaxis is open to question. This study was undertaken to determine whether enoxaparin reduced the clinical utility of surveillance scanning and whether management of these patients was altered by findings of the scans. METHODS: The medical records of trauma patients who met defined criteria for high DVT risk, admitted during 30 consecutive months, were reviewed. These patients received enoxaparin 30 mg every 12 hours for the duration of their admissions. Per protocol, surveillance lower extremity venous duplex scans were performed within 72 hours of enoxaparin administration and then weekly until patients were discharged from the hospital. The records were reviewed for thromboembolic events (DVT or pulmonary embolism [PE]), patient location and ambulatory status, therapeutic interventions (systemic anticoagulation, vena cava filter), and complications of enoxaparin therapy. RESULTS: A total 241 patients underwent 513 venous duplex examinations (1-13 per patient). Eight patients had DVT on the initial scan; seven of these patients were asymptomatic. Five were treated with anticoagulation and/or vena cava filter placement. Of the 233 patients with initially negative duplex scan results, five patients (2%) developed clinically unsuspected lower extremity DVT while hospitalized. All of these five patients were in an intensive care unit. Three of the five patients had no change in treatment. Two of the five underwent anticoagulation, and one vena cava filter was placed. PE occurred in two hospitalized patients, one of whom was ambulatory, with negative duplex scan results. After hospital discharge, six other patients had symptomatic DVT or PE despite in-hospital scans with negative results. Complications associated with enoxaparin included hemorrhage (2) and thrombocytopenia (8). CONCLUSIONS: After initial negative scan results, repeat surveillance duplex scanning during hospitalization detected a low incidence (2%) of DVT in high-risk patients. Furthermore, the detection of unsuspected DVT altered the clinical management of less than 1% of the patients tested. Thus, after a venous duplex scan with negative results and initiation of enoxaparin prophylaxis, subsequent surveillance duplex examinations are not warranted in asymptomatic trauma patients.

Adolescent↗

PubMed2001

Surgical management of thrombotic acute intestinal ischemia.

OBJECTIVE: To evaluate the University of Kentucky experience in treating acute intestinal ischemia to elucidate factors that contribute to survival. SUMMARY BACKGROUND DATA: Acute intestinal ischemia is reported to have a poor prognosis, with survival rates ranging from 0% to 40%. This is based on several reports, most of which were published more than a decade ago. Remarkably, there is a paucity of recent studies that report on current outcome for acute mesenteric ischemia. METHODS: A comparative retrospective analysis was performed on patients who were diagnosed with acute intestinal ischemia between May 1993 and July 2000. Patients were divided into two cohorts: nonthrombotic and thrombotic causes. The latter cohort was subdivided into three etiologic subsets: arterial embolism, arterial thrombosis, and venous thrombosis. Patient demographics, clinical characteristics, risk factors, surgical procedures, and survival were analyzed. Survival was compared with a collated historical series. RESULTS: Acute intestinal ischemia was diagnosed in 170 patients. The etiologies were nonthrombotic (102/170, 60%), thrombotic (58/170, 34%), or indeterminate (10/170, 6%). In the thrombotic cohort, arterial embolism accounted for 38% (22/58) of the cases, arterial thrombosis for 36% (21/58), and venous thrombosis for 26% (15/58). Patients with venous thrombosis were younger. Venous thrombosis was observed more often in men; arterial thrombosis was more frequent in women. The survival rate was 87% in the venous thrombosis group versus 41% and 38% for arterial embolism and thrombosis, respectively. Compared with the collated historical series, the survival rate was 52% versus 25%. CONCLUSIONS: These results indicate that the prognosis for patients with acute intestinal ischemia is substantially better than previously reported.

Age Factors↗

PubMed2001

Telemedicine in vascular surgery: does it work?

Telemedicine (TM) using closed-circuit television systems allows specialists to evaluate patients at remote sites. Because an integral part of the vascular examination involves palpation of peripheral pulses the applicability of TM for the evaluation of vascular surgery patients is open to question. This study was carried out to test the hypothesis that TM is as effective as direct patient examination for the development of a care plan in vascular patients. Sixty-four vascular evaluations were done in 32 patients. The patients presented with a variety of vascular problems and were seen in regularly scheduled rural outreach vascular clinics. Two faculty vascular surgeons evaluated each patient; one was on site and the second, using TM, remained at the medical center. Each surgeon was blinded to the other's findings. The TM physician was aided by a nonphysician assistant, who obtained blood pressures, utilized a continuous-wave Doppler probe, positioned the patient, and operated the TM equipment. The results of each surgeon's evaluations were compared. Patient and physician satisfaction with the TM evaluation was appraised by questionnaires. Eight patients were seen for initial evaluations; 24 patients were seen for follow-up visits. Patients were seen with a variety of diagnoses, including aneurysm (seven), cerebrovascular disease (five), lower extremity occlusive disease (13), multiple vascular problems (three), and other disease (four). The average duration for the TM and on-site evaluations were 20.6+/-1.4 and 19.0+/-1.3 minutes, respectively (P = not significant). Physician concordance, as determined by treatment recommendations, was the same in 29 (91%) patients. Physician confidence in the ability to obtain an accurate history via TM was rated as excellent in 97 per cent; confidence in the TM physical examination was rated as excellent in 70 per cent. All patients rated the TM evaluation as the "same as" or "better than" the on-site examination, and all indicated a preference for being seen locally using TM as opposed to traveling to a regional medical center. We conclude that the TM evaluation of vascular patients is accurate and is as effective as on-site evaluations for a variety of vascular problems. Important adjuncts to enhance the success of a TM evaluation are physician experience with the technology and the presence of a knowledgeable on-site assistant. This technology can be easily adapted to other clinical situations.

Academic Medical Centers↗

PubMed1998

Process improvements reduce utilization of resources for aortic aneurysm repair.

In conjunction with the VA reorganization to promote greater efficiency of health care provision, ambulatory surgery (AS) programs have been created. These programs institute outpatient preoperative assessment and operative management. This study examines the impact of these process changes on resources utilized by patients requiring repair of abdominal aortic aneurysms (AAAs). The medical records of 15 consecutively treated patients undergoing elective, infrarenal AAA repair before (1992-1993) and after (1995-1996) AS implementation were reviewed. Resource utilization was assessed by evaluating preoperative tests performed (inpatient or outpatient), ICU days, and inpatient length of stay (LOS). Postoperative morbidity and mortality were noted. Patient age, AAA size, and prevalence of diabetes mellitus, hypertension, cardiac disease, COPD, and tobacco use were similar between the two groups. Abdominal ultrasound, CT scanning, and angiography were significantly more frequently performed on an outpatient basis after implementation of the AS program. The median preoperative LOS was reduced in the AS group (1 vs 6 days, P = 0.001, Student t test), resulting in a lower inpatient LOS (11 vs 16, P < 0.01, Student t test). All patients survived and the incidence of complications was similar between the groups. Hospital resource utilization was significantly decreased, largely by shifting preoperative assessment to the outpatient setting. This study illustrates that benefits of an ambulatory surgery program can be extended beyond facilitating outpatient operations and should result in decreased length of hospitalization for other major surgical procedures, such as abdominal aortic aneurysm repair.

Aged↗

PubMed1998

Nontraumatic lower-extremity acute arterial ischemia.

BACKGROUND: The outcome of arterial bypass reconstruction in the setting of acute arterial ischemia has not been well defined. METHODS: This retrospective review consists of 71 consecutive patients (54 with native arterial thrombosis, 17 with graft thrombosis) who underwent an urgent/emergent arterial bypass reconstruction for acute arterial ischemia with threatened limb viability. RESULTS: The 30-day mortality and major amputation rates were 9.9% and 7.1%, respectively. Death, limb loss, or both, were associated with a paralytic limb (P = 0.001) and congestive heart failure (P = 0.03). Overall, 45 of 71 (63%) patients were discharged with limb salvage and ambulatory function. Cumulative graft patency was 77% and 65% at 1 and 2 years, respectively, and closely approximated the 1- and 2-year limb-salvage rates of 76% and 63%, respectively. CONCLUSIONS: Arterial bypass reconstructions appear warranted in acute arterial ischemia, in that a majority of patients retain a functional viable limb. Late graft thrombotic complications limit long-term benefit.

Acute Disease↗

PubMed1998

Popliteal artery thrombosis associated with trampoline injuries and anterior knee dislocations in children.

Recent reports have emphasized the benign nature of trampoline-associated injuries. However, this study describes the limb-threatening problem of popliteal artery thrombosis occurring in association with anterior knee dislocation and trampoline injuries. Three children (ages 11, 13, and 17) were referred to the emergency room within the past 12 months with anterior dislocations of the knee, which occurred while jumping on trampolines. All patients had reduction of their dislocations at outside facilities and were referred within 6 to 12 hours after their injuries, with pulse, motor, and sensory deficits. All patients were taken directly to the operating room, where arteriography confirmed thrombosis of the popliteal artery below the knee. One patient had transection of the artery, whereas two patients had stretch injuries with intimal separation. Each patient required interposition grafting with reversed saphenous vein and underwent concomitant four-compartment fasciotomy. All patients had persistent sensory and motor deficits postoperatively, which were presumed to be a combination of ischemic injury and neuropraxia. All patients have functioning grafts with an average follow-up of 1 year (range, 9-15 months). One patient required a second interposition graft to treat an area of intimal hyperplasia, which developed at the proximal anastomosis, at 6 months postoperatively. Eighty per cent of trampoline injuries are associated with minor injuries with minimal long-term complications. However, dislocations of the knee may be associated with significant arterial injury and amputation rates of up to 30 per cent in many blunt trauma series. Based on our experience, physicians should recognize the possibility of significant arterial injuries occurring in children with anterior knee dislocations while jumping on trampolines.

Adolescent↗

PubMed1995

An angioscopic method for intraluminal aortic evaluation and stent placement.

PURPOSE: The purpose of this study was to develop an angioscopic technique to visualize the endoluminal surface of the aorta and to guide vascular stent placement. METHODS: A fiberoptic angioscope, fitted with a balloon at its tip, was passed via a carotid arteriotomy into the abdominal aorta of seven anesthetized pigs. Saline solution inflation of the balloon allowed for blood displacement and clear visualization of the endoluminal anatomy. After the left renal artery orifice had been identified with angioscopy, a catheter was inserted via a left femoral sheath to cannulate the orifice under direct visualization. The position of the catheter was verified angiographically. A vascular stent was loaded onto an angioplasty balloon, inserted through a right femoral arteriotomy, positioned by use of angioscopic visualization, and deployed immediately below the left renal artery orifice. RESULTS: The aortic trifurcation and the lumbar and renal artery orifices were clearly visualized in every animal. Vascular stents were placed in seven animals within an average of 3.14 +/- 1.14 mm (mean +/- SEM, range 0 to 8 mm) below the inferior rim of the left renal artery orifice. No stents were positioned above a renal artery orifice or obstructed blood flow. CONCLUSIONS: This angioscopic technique permitted detailed evaluation of aortic endoluminal anatomy and precise implantation of vascular stents. Direct endovascular visualization may facilitate other endovascular procedures, including endovascular grafting.

Angioscopy↗

PubMed1994

Morphology predicts rapid growth of small abdominal aortic aneurysms.

This study evaluated CT scans of small abdominal aortic aneurysms (AAAs) (< 5 cm) to assess anatomic features associated with rapid expansion. Serial CT scans obtained at least 10 months apart (mean 15 months) from patients with small AAAs were reviewed. Each cross-sectional image of the AAAs was analyzed using a computer-assisted design program. The circumference of the AAA in each CT image was divided into eight equal arcs, from which the apparent radius of curvature (Rc) for each segment was calculated. Flattening of the wall curvature results in an increased segmental Rc. The CT scans of nine patients with expanding AAAs (expansion > or = 0.5 cm/yr) were compared to those of 10 patients with stable AAAs (expansion < or = 0.2 cm/yr). To adjust for differences in AAA size, the Rc for each segment was normalized by dividing each individual Rc by the average of the eight Rcs (RcAvg) calculated for that cross-sectional CT image. Analysis of variance showed that the left posterolateral segments in expanding AAAs had larger Rc/RcAvg ratios than those segments in stable AAAs (1.14 +/- 0.19 vs. 0.80 +/- 0.09, p < 0.02). Laplace's law indicates that the left posterolateral segment in AAAs that grow more rapidly is subjected to greater wall tension. Flattening in the curvature of the left posterolateral wall segment was significantly associated with an increased rate of expansion in small AAAs. This finding, readily derived from standard CT scan images, may predict which small AAAs are more prone to rapid expansion.

Aortic Aneurysm, Abdominal↗

PubMed1994

Performance of the vascular physical examination by residents and medical students.

PURPOSE: This study uses an objective structured clinical examination to evaluate the performance and interpretation of the vascular physical examination by interns and medical students. METHODS: A patient with lower extremity arterial occlusive disease findings was examined by 20 third-year students (M3), 23 physicians entering surgical internship (PGY1), and 7 individuals completing internship (PGY2). The test consisted of two sections: part A evaluated the individuals' ability to perform a pulse examination (data gathering); part B evaluated the interpretation of the physical examination findings (data interpretation). National Board of Medical Examiners Part II examination results were obtained for 84% of participants. RESULTS: All groups performed poorly, with overall correct percent scores being 43% (M3), 39% (PGY1), and 62% (PGY2). PGY2s performed significantly better than M3s or PGY1s (p = 0.0002). No statistical difference was noted between M3 and PGY1 scores. Overall, data gathering skills were significantly better than data interpretation skills (51% vs 37%, p = 0.0001). National Board of Medical Examiners Part II scores did not vary substantially among groups. CONCLUSIONS: Interns and medical students demonstrated considerable inaccuracy in both data gathering and data interpretation. A modest improvement was observed in individuals tested at the end of the internship year. This study suggests that increased attention should be directed toward instructing surgical residents and students how to perform an accurate peripheral vascular physical examination and how to interpret its significance.

Arterial Occlusive Diseases↗

PubMed1994

A comparison of operative approaches and parameters predictive of success in multilevel arterial occlusive disease.

BACKGROUND: The correction of abnormal inflow alone in patients with multilevel arterial occlusive disease (MLAOD) may be inadequate to relieve limb-threatening ischemia. This study was undertaken to compare operative approaches and attempt to define preoperative parameters predictive of limb salvage in patients with MLAOD. STUDY DESIGN: The outcome after revascularization for 194 patients with limb-threatening ischemia MLAOD was assessed retrospectively. One hundred fifty-one patients initially underwent an inflow operation alone. Based on whether or not these patients required an outflow operation within one year, they were divided into two groups: group 1, no outflow operation (121 patients, 121 limbs), and group 2, outflow operation required for continued ischemic symptoms (30 patients, 30 limbs). A separate group of forty-three patients (43 limbs) underwent synchronous inflow-outflow operations, or multilevel revascularization, as their initial operative procedure (group 3). RESULTS: Perioperative complications and mortality rates did not differ between groups. Limb salvage rates were similar for groups 1 and 3, whereas in group 2, limb salvage rates were significantly reduced (p = 0.0184). Long-term limb salvage after an isolated inflow procedure was associated with lack of prior vascular reconstructions (p = 0.0002), the absence of tissue loss (p = 0.0019), and an infrageniculate angiographic runoff score of less than 6 (p = 0.054). CONCLUSIONS: In patients with limb-threatening MLAOD, synchronous inflow-outflow operations can be performed with resultant morbidity and mortality rates comparable with inflow alone. After an inflow operation, the approach of "expectant management" may ultimately compromise limb salvage if a subsequent outflow operation is required.

Adult↗

PubMed1993

Thromboembolic complications of polycythemia: polycythemia vera versus smokers' polycythemia.

PURPOSE: This report compares patients with the hypercoagulable state of polycythemia vera to patients with secondary polycythemia caused by tobacco use to determine whether the incidence of thromboembolic events is equivalent. METHODS: The medical records of 146 patients with the diagnosis of polycythemia between 1977 to 1990 were reviewed. Patients with transient, relative, or stress polycythemia were excluded from this study as were patients with polycythemia as a result of cardiac or pulmonary anomalies or both. The diagnosis of polycythemia vera (n = 43) was verified by use of the guidelines of the Polycythemia Vera Study Group. The diagnosis of polycythemia caused by smoking (n = 27) was based on an elevated total red blood cell volume, decreased oxygen saturation on arterial blood gas measurement, evidence of chronic obstructive pulmonary disease, and elevated carboxyhemoglobin levels. RESULTS: Twenty-six patients (60%) with polycythemia vera and 11 patients (41%) with smoker's polycythemia had at least one thromboembolic problem. No significant differences existed between the groups with regard to age, hematocrit, or number of cardiac and cerebrovascular events. Overall, patients with polycythemia vera had a greater number of thromboembolic events per patient (p < 0.05) and more peripheral arterial thromboemboli (p < 0.005) than did patients with polycythemia as a result of smoking (Fisher's Exact Test). CONCLUSIONS: Thus the results of this study demonstrate that smokers' polycythemia does not represent a hypercoagulable state equivalent to that of polycythemia vera.

Analysis of Variance↗

PubMed1992

Recognition of arterial injury in elbow dislocation.

The clinical presentation of patients with elbow dislocations was reviewed to identify those factors indicating an increased risk for arterial injury. Sixty-two patients were treated for 63 elbow dislocations between January 1981 and July 1991. Eight patients (13%) sustained a concomitant arterial injury involving the brachial (7) and radial (1) arteries. Three clinical findings, absence of a radial pulse, open dislocation, and presence of systemic injuries, were correlated with arterial injury. A palpable radial pulse was absent in six (75%) patients with an arterial injury but in only two (4%) with normal vessels (p less than 0.0001, chi square). Five (33%) open dislocations had an associated arterial injury, whereas three (6%) arterial injuries occurred in closed dislocations (p less than 0.006, chi square). Systemic injury occurred in five dislocations (63%) with arterial injuries and 14 dislocations (25%) without arterial injury (p less than 0.04, chi square). Multivariate analysis showed that absence of a radial pulse was the only factor that significantly predicted arterial injury (p less than 0.0001). Although most elbow dislocations are not associated with arterial injury, absence of a radial pulse or presence of an open dislocation or both should alert the clinician to the increased possibility of an associated vascular injury.

Adult↗

PubMed1991

A nine-year experience with crossover femoro-femoro-popliteal sequential bypass.

Multisegmental arterial occlusive disease may require a combined inflow and outflow procedure for optimal treatment of limb ischemia. Twenty-one patients with unilateral iliac artery stenosis or occlusion and ipsilateral superficial femoral artery occlusion underwent crossover femoro-femoro-popliteal sequential bypass during a 9-year period. Seventeen operations were for limb salvage. Patency rates were determined separately for each segment of the bypass. Primary patency rates for the femoro-femoral segment were 89%, 83%, and 57% at 1, 2, and 5 years, respectively. Primary patency rates for the femoro-popliteal segments were 68%, 62%, and 40% at 1, 2, and 5 years, respectively. Limb salvage rates were 100%, 90%, and 77% at 1, 2, and 5 years, respectively. This experience indicates that femoro-femoro-popliteal bypass is an effective treatment in selected patients with severe ischemia due to combined iliac artery and superficial femoral artery disease.

Aged↗

PubMed1991

Prostacyclin production in the area of arterial endothelial denudation.

The goal of this study was to quantify arterial prostacyclin (PGI2) synthesis and platelet aggregation in the immediate area of vessel injury. Twelve mongrel dogs whose platelets aggregated maximally to added arachidonic acid (AA) were equally divided into three groups. Controls received no drug while other dogs were treated with the platelet inhibitors aspirin (ASA) 3 mg/kg/day or BM 13.505 (BM), a thromboxane receptor antagonist, 25 mg/kg/day. After 3 days of treatment, the dogs underwent balloon catheter endothelial denudation of both carotid and femoral arteries. Blood was sampled from the first carotid artery just distal to the injury at 0, 1, 5, and 10 min after restoration of flow. Venous blood samples were also obtained at 1 and 2 weeks postoperatively. Dogs were sacrificed at 2 weeks and arterial rings from a proximal normal and a denuded region were excised and tested for PGI2 production in response to added AA. While control dogs showed no statistical change in AA-induced platelet aggregation postoperatively, there appeared to be a trend for enhanced responsiveness at 1 week. Aspirin and BM inhibited AA-induced aggregation completely in all samples at all timepoints. Levels of the stable metabolite of PGI2, 6-keto-PGF1 alpha, were determined by radioimmunoassay. In control dogs, baseline PGI2 levels were 72 +/- 17 pg/ml which increased to 479 +/- 20 pg/ml immediately after restoration of flow (P less than 0.001, Student t test) and returned to basal values in 10 min (85 +/- 5 pg/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Hip disarticulation: factors affecting outcome.

Hip disarticulation, especially in patients with peripheral vascular disease, has been associated with high morbidity and mortality rates. This report describes patient characteristics that influence the clinical outcome of hip disarticulation. The medical records of all patients undergoing hip disarticulation from 1966 to 1989 were reviewed for surgical indication, perioperative wound complications, and postoperative deaths. Fifty-three patients underwent hip disarticulation for limb ischemia (10), infection (12), infection and ischemia (14), or tumor (17). The overall incidence of wound complications was 60%, and no significant differences were found among the groups. Prior above-knee amputation and urgent/emergent operations were significantly associated with increased wound complications (p less than 0.05). The overall mortality rate was 21%, ranging from 0% (tumor) to 50% (ischemia) and differed significantly among the groups (p less than 0.02). Mortality was significantly associated with urgent/emergent operations (p less than 0.01). Age, diabetes mellitus, and previous inflow procedures did not influence mortality rates. The presence of limb ischemia influenced mortality rates to a greater extent than did infection, and a history of cardiac disease was statistically predictive of death. Wound complications frequently accompanied hip disarticulation, regardless of operative indication, and were significantly increased by urgent/emergent operations and prior above-knee amputation. Hip disarticulation can be performed with low mortality rates in selected patients. Both limb ischemia and infection substantially increase operative mortality rates.

Adult↗

PubMed1991

Autogenous vein graft repair of injured extremity arteries: early and late results with 134 consecutive patients.

Autogenous vein tissue is recognized as the preferred material for extremity revascularizations that require the use of a conduit. However, the results after vascular repair of injured extremity arteries with autogenous vein interposition or bypass grafts have not been well defined. This study was done to determine both the early and late patency and limb salvage rates as well as the graft infection rate of autogenous vein repairs of injured extremity arteries. The records of 134 consecutive patients with acute extremity arterial injuries requiring repair with a reversed autogenous vein graft over a recent 5-year period were reviewed. Follow-up graft patency was defined by the presence of a palpable pulse and an extremity Doppler-derived pressure index of greater than or equal to 0.9 distal to the arterial repair. Cumulative patency was assessed by the life-table method. Acute graft thrombosis occurred in two patients, one of whom underwent successful graft thrombectomy. Four patients (3%) required extremity amputation: one patient with a thrombosed vein graft and three patients with patent vein grafts but nonsalvageable limbs as a result of myonecrosis (2) or osteomyelitis (1). No perioperative graft infections occurred. One hundred twenty-eight patients (97%) had an intact extremity and a patent vein graft at the time of hospital discharge. One hundred three patients (80%) were examined at 30 days, and all grafts were patent. Seventy-three patients (57%) were available for follow-up at intervals exceeding 6 months, and 40 patients (31%) were followed-up for periods exceeding 24 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1990

Longitudinal retractive force in pressurized dog and human arteries.

Experiments were performed to examine longitudinal retractive force in pressurized arteries in vitro. This force opposes vessel elongation and prevents the development of tortuosity. Common carotid arteries were excised from six adult dogs and external iliac arteries were excised from six elderly male humans at autopsy. Each vessel was mounted in a tissue bath at in situ length and was pressurized. Longitudinal retractive force was measured under control conditions and after treatment with elastase or collagenase. Results showed that, in the dog vessels, elastin provides all of the longitudinal retractive force. In the aged human vessels, both elastin and collagen provide longitudinal retractive force, with elastin contributing the much greater part.

Age Factors↗

PubMed1990

A rapid, accurate, noninvasive technique for diagnosing critical and subcritical stenoses in aortoiliac arteries.

Accurate hemodynamic evaluation of the aortoiliac system for the purpose of determining the need for an inflow procedure currently requires invasive pressure measurements. This study was undertaken to evaluate a noninvasive technique with the aortofemoral transfer function. Twenty-eight human aortoiliac segments were studied with intraarterial pressure measurements, with and without papaverine injection, and by calculation of the Doppler-derived mean power frequency index obtained by digital signal processing of aortic and femoral spectra. The procedure is menu driven and can be performed by any duplex ultrasound technologist. This technique involves recording 20 aortic and 20 femoral Doppler signals, requiring less than 1 minute of data acquisition time. Intraarterial pressure measurements were used to classify arteries into the three following groups: (1) normal arteries, (2) arteries with subcritical stenoses, and (3) arteries with critical stenoses. The mean power frequency index of group 1 arteries (n = 7) was 0.63 +/- 0.04, of group 2 arteries (n = 6) was 0.46 +/- 0.02, and of group 3 arteries (n = 15) was 0.21 +/- 0.05. These mean power frequency index values were significantly different by analysis of variance (ANOVA) (p less than 0.0001). Each group could be differentiated from the other groups with a sensitivity of 0.83 to 1.00, a specificity of 1.00, and an accuracy of 0.92 to 1.00 compared to intraarterial pressure measurements, including papaverine testing. Measurement of the mean power frequency index is a rapid, noninvasive technique that diagnoses and quantifies aortoiliac stenoses with an accuracy similar to intraarterial pressure measurements.

Aortic Diseases↗