Biomedical subjects

T R Harward

Publications and source records attributed to T R Harward.

36 records · Page 2Linked to original sources

PubMed1993

Detection of celiac axis and superior mesenteric artery occlusive disease with use of abdominal duplex scanning.

PURPOSE: Detection of mesenteric arterial insufficiency is clinically difficult, and diagnosis frequently requires arteriography. Advances in duplex scanning make this an ideal technique to noninvasively screen patients for chronic mesenteric arterial occlusive disease. However, the accuracy of mesenteric duplex scanning compared with arteriography remains unclear. This study will clearly define the accuracy of abdominal duplex scanning for detection of mesenteric arterial insufficiency. METHODS: The mesenteric duplex scans of 38 patients obtained over a 4-year period were reviewed and compared with lateral aortograms to clarify this issue. Optimal peak systolic frequency (PSF) for predicting less than 50% or 50% or greater stenoses of the superior mesenteric artery (SMA) and celiac axis (CA) were determined from receiver-operating characteristic curves. RESULTS: In the SMA a PSF of 4.5 kHz was 96% sensitive (24/25), 92% specific (12/13), and 95% accurate (36/38) at predicting stenoses less than 50% or 50% or greater. For arteries with stenoses 50% to 99%, regression analysis demonstrated excellent linear correlation between percent stenosis and PSF (r = 0.89). In the CA a PSF of 4.0 kHz had a sensitivity of 100% (30/30), a specificity of 88% (7/8), and an accuracy of 97% (37/38). Again, for arteries with stenoses 50% to 99%, an excellent linear correlation existed between PSF and percent stenosis (r = 0.86). All total arterial occlusions (14) were correctly identified. In all, mesenteric arterial duplex scanning was 96% accurate for predicting SMA and CA stenoses/occlusions. CONCLUSIONS: Abdominal duplex scanning is a noninvasive technique that accurately detects total occlusions and objectively quantitates SMA and CA arterial stenoses.

Aorta, Abdominal↗

PubMed1993

Follow-up evaluation after renal artery bypass surgery with use of carbon dioxide arteriography and color-flow duplex scanning.

PURPOSE: Postoperative evaluation of renal artery bypass grafts historically has been obtained by contrast renal arteriography before discharge from the hospital. Recent reports have advocated replacing arteriography with abdominal duplex scanning for evaluating and monitoring the integrity of renal artery bypasses. We propose a combination of these two techniques, which provides minimal risk to the patient and renal parenchymal function. PURPOSE: Between July 1, 1990, and Dec. 31, 1991, 17 patients (8 men, 9 women) underwent 24 renal artery bypasses for poorly controlled hypertension or deteriorating renal function. In the immediate postoperative period each patient underwent carbon dioxide (CO2) renal arteriography to detect any technical defects and to define bypass graft anatomy. Subsequently, color-flow duplex scanning of the renal artery bypass grafts were done at 3-month intervals with the postoperative CO2 arteriogram for baseline comparison. CO2 arteriography clearly defined proximal/distal anastomotic anatomy, bypass conduit integrity, and bypass conduit runoff. RESULTS: Procedural morbidity was zero because no hematomas developed and serum creatinine remained stable. Duplex scanning for a mean follow-up of 8.3 months revealed antegrade flow in 23 bypasses with peak systolic velocity of 60 to 100 cm/sec. One bypass graft had a peak systolic velocity greater than 150 cm/sec suggestive of a proximal anastomotic stenosis; however, the patient died before a repeat, verifying CO2 arteriogram could be obtained. Recurrent hypertension developed in one patient with velocities less than 100/cm/sec, and repeat CO2 arteriography revealed no evidence of graft or anastomotic stenosis. CONCLUSION: CO2 arteriography and duplex scanning provide an accurate means of initially evaluating and subsequently monitoring renal artery bypass grafts, with minimal risk of renal or patient morbidity.

Adult↗

PubMed1993

Multiple organ dysfunction after mesenteric artery revascularization.

PURPOSE: Mesenteric arterial reconstruction in patients with acute or chronic intestinal ischemia is associated with significant morbidity and mortality rates. Reperfusion of ischemic bowel in animals leads to release of multiple factors that cause organ dysfunction. Similar phenomena potentially occur in human beings after repair of symptomatic chronic mesenteric arterial disease. The purpose of this study was to define the incidence of multiple organ dysfunction seen after reperfusion of the chronically ischemic bowel. METHOD: Between January 1990 and January 1993, 18 patients underwent surgical revascularization for symptomatic chronic mesenteric arterial occlusive disease. Four patients required emergency surgery, whereas 14 procedures were done electively. Hepatic, renal, pulmonary, and coagulation function were evaluated in all patients. Bypass graft patency was confirmed by duplex scanning or repeat operation in all patients with deteriorating conditions. RESULTS: Immediately after surgery hepatic function deteriorated. The serum transaminases increased 90- to 100-fold whereas lactate dehydrogenase increased 25-fold. Simultaneously, platelet counts dropped below 40,000 mm3 in 11 patients. On postoperative day 2, 16 patients had acute pulmonary insufficiency demonstrated by an increase in the pulmonary shunt fraction to a mean of 32% +/- 3% (range 21% to 60%). Ten patients required reintubation, and lung failure lasted an average of 8.4 days (range 1 to 35 days). Hepatic and coagulation function changes were usually transient, returning to baseline within 7 to 10 days. Four of the patients who had multiple organ dysfunction died (two after elective surgery), and one patient died of myocardial infarction after emergency surgery. CONCLUSION: Revascularization of chronically ischemic bowel leads to significant multiple organ dysfunction, potentially as a result of intestinal ischemia and reperfusion injury.

Adult↗

PubMed1993

Carbon dioxide gas as an arterial contrast agent.

OBJECTIVE: To investigate the clinical utility of CO2 gas as an arterial contrast agent, the experience with CO2 arteriography at the University of Florida was reviewed. SUMMARY BACKGROUND DATA: Preliminary studies have demonstrated the feasibility of CO2 arteriography and shown that arterial injection of CO2 gas appears non-toxic (which could limit the risks of contrast induced renal injury and allergic reaction). However, numerous technical problems make CO2 arteriography a demanding technique and recent studies have suggested that distal lower extremity vessels are difficult to image using CO2 arteriography, especially when significant arterial occlusive disease is present. METHODS: One hundred twenty-eight CO2 arteriograms done in 115 patients were reviewed. CO2 arteriograms were graded as excellent, good, poor, or inadequate by two blinded observers and results of CO2 studies compared to results of standard contrast studies (done in 98 patients for image comparison). In addition, a therapeutic plan based on the CO2 arteriograms was compared with the therapy each patient received. RESULTS: One hundred-seventeen (91%) of the CO2 arteriograms were of good or excellent quality and agreement between CO2 studies and standard contrast studies was seen in 93 of 98 cases (95%). Accurate therapeutic plans based on CO2 studies were possible in 92% of cases with inadequate visualization of infrapopliteal arteries being the major limitation (7 cases). No allergic reactions occurred and only one patient potentially had contrast-induced nephrotoxicity. CONCLUSIONS: CO2 arteriography provides accurate, clinically useful arterial imaging with minimal risk. Thus, this new technology significantly increases the utility of arteriography in patients with peripheral vascular disease.

Adult↗

PubMed1992

The use of arm vein conduits during infrageniculate arterial bypass.

To further examine the use of arm vein for bypass to the popliteal or infrapopliteal arteries, we retrospectively reviewed 43 patients undergoing infrageniculate arterial bypass by use of an arm vein as a conduit. Nine grafts were done to the below-knee popliteal artery and 34 to the infrapopliteal arteries. Six grafts were done by use of a single segment of an arm vein, whereas 37 grafts were composites of either multiple segments of arm vein (n = 19) or segments of saphenous and arm vein (n = 18). Mean follow-up time was 15 1/2 months. Initial (30-day) graft patency and limb salvage were 95%. Primary graft patency by life-table analysis was 67% at 1 year and 49% at 3 years. Follow-up examination detected graft stenosis before occlusion in six patients (all of whom were given anticoagulant medication) and three failing grafts were salvaged. This increased overall 3-year secondary graft patency to 64% and 3-year secondary patency for infrapopliteal bypasses to 66%. Eleven of 12 graft occlusions resulted in major amputations (eight were above the knee, and three were below the knee) so that limb salvage paralleled secondary graft patency (63% at 3 years). Thus arm veins provide an excellent alternative venous conduit for infrageniculate arterial bypass, even when composite venous grafts must be used.

Aged↗

PubMed1991

Vascular trauma as a result of therapeutic procedures for the treatment of malignancy.

Twenty-two iatrogenic vascular injuries caused by resection of tumors with local recurrences or adjuvant chemotherapy were treated over a 42-month period in 11 female and 8 male patients with cancer (58% had documented metastases). Sixteen of 22 vascular injuries were caused by intraarterial administration of chemotherapy (8 emboli; 8 direct catheter trauma), and six were caused by resection of tumors with local invasion. The injuries were extremity ischemia (15 extremities in 13 patients), pseudoaneurysm (4), expanding hematoma (3 injuries in 2 patients). Twenty-two surgical repairs included bypass of severely damaged arteries in five, embolectomy in five, interposition grafts in three, pseudoaneurysm resection and primary repair in three, primary repair of three vascular injuries, and one patch angioplasty. Leg amputation was required in two patients. Seventeen of 19 patients had successful vascular repairs with resolution of preoperative indications for vascular repair without intraoperative or postoperative deaths. Long term follow-up (mean, 17 months) showed no recurrence of vascular problems; however, two patients died of metastatic cancer at 6 and 24 weeks after vascular repair. This study supports an aggressive approach to the management of vascular injuries caused by therapeutic interventions for malignancy despite the presence of metastatic disease.

Adolescent↗

PubMed1991

Isolated subclavian artery dissection after blunt trauma.

We present a case report of a patient with an isolated dissection of the subclavian artery after blunt trauma. The patient who was admitted to our center after a motor vehicle accident, complained of chest and neck pain and physical findings of diminished left extremity pulses. Arteriography showed an occluded subclavian artery with the possibility of a dissection. The dissection was confirmed at surgery with the proximal extent originating just distal to the origin of the vertebral artery. The distal extent of the dissection was not determined. Operative repair was performed by a carotid-to-subclavian artery bypass obliterating the false lumen of the dissection with a running vascular anastomosis. The patient, who was discharged 5 days after repair, had normal extremity neurovascular function at 4 months follow-up.

Accidents, Traffic↗

PubMed1990

Complex upper extremity vascular trauma in an urban population.

Eighty patients with upper extremity vascular trauma were treated during a 4-year period. Of 123 vascular injuries, 95 were arterial, 1 was primary venous, and 27 were associated venous injuries. Causes included penetrating (64%), blunt (27%), and iatrogenic injuries (9%). Arteries injured were ulnar (34), radial (28), brachial (22), subclavian (6), and axillary (5). Numbers of patients with associated injuries were nerve (53), vein (27), bone (23), and soft tissue injuries (60). The most common techniques of arterial repair were end-to-end anastomosis (50), followed by interposition saphenous vein grafting (40). Fasciotomy was used in 36 patients. Two arterial repairs failed during surgery and required revision (1) or thrombectomy (1). One radial artery repair thrombosed during late follow-up, with maintenance of normal extremity perfusion via the ulnar artery. No amputations were required, and 83% of all patients treated for nerve injuries resolved or improved their neurologic deficits. Two or more operations for surgical debridement and subsequent wound closure were required in 35 patients. This study supports an aggressive approach to diagnosis and treatment of complex upper extremity vascular trauma emphasizing meticulous surgical technique, liberal use of fasciotomy, and aggressive intraoperative debridement and repair of associated injuries.

Arm Injuries↗

PubMed1989

Duplex ultrasound measurement of changes in mesenteric flow velocity with pharmacologic and physiologic alteration of intestinal blood flow in man.

Duplex ultrasound scanning has been used to assess mesenteric blood flow in normal and disease states. To investigate this technique we studied nine normal volunteers at rest and under conditions known to modify intestinal blood flow. After a baseline mesenteric duplex scan, each subject was given one of three treatments in random order: (1) test meal (710 kcal), (2) intravenous glucagon (40 micrograms/min), or (3) intravenous vasopressin (0.2 units/min). Peak systolic and diastolic velocities and vessel diameters were measured at intervals after treatment in the celiac and the superior mesenteric arteries (SMAs) and the right common carotid artery. Resting velocities did not differ among the groups. Peak systolic velocity increased significantly in both celiac and SMAs after the meal, with maximal changes in the celiac artery preceding those in the SMA in most subjects. Early diastolic flow reversal in the SMA was consistently lost after the meal (eight of nine subjects). Velocity changes after glucagon closely paralleled those after the meal. Vasopressin produced significant decreases in peak systolic velocity in both visceral vessels. No changes in vessel diameter were noted after any treatment. Coefficient of variation for repeated measures of peak velocities was 19% in the celiac and 12% to 16% in the SMA and the common carotid. The coefficient of variation for repeated measurements of arterial diameter was 6% to 8% in the SMA and 11% in the celiac artery. Clinically relevant changes in mesenteric hemodynamics can be reproducibly detected and quantitated by means of current duplex ultrasound technology. The similarities between the visceral arterial responses to a meal and glucagon are of interest.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1989

Mesenteric venous thrombosis.

Sixteen patients with mesenteric venous thrombosis were reviewed retrospectively during a period from 1983 to 1987. Twelve patients had progressive abdominal pain, three had gastrointestinal bleeding, and one had general malaise. Seven of these 16 patients had previous deep-vein thrombosis. After negative routine gastrointestinal and hepatobiliary evaluation, 11 patients underwent an infusion computerized tomographic scan. Of these, 10 had superior mesenteric vein thrombosis; three of these 10 patients had portal vein thrombosis. Selective arteriography was done in two patients because of gastrointestinal bleeding, and a diagnosis of mesenteric vein thrombosis was made on the venous phase of the examination. The remaining four patients developed acute abdominal symptoms requiring surgical exploration, at which time mesenteric venous thrombosis was discovered. An identifiable coagulopathy was detected in nine patients (protein C deficiency in six, protein S deficiency in two, and factor IX deficiency treated with factor IX concentrate in one). No case of congenital antithrombin-III deficiency was identified. Six of these nine patients had a past history of deep venous thrombosis. Of five patients who underwent surgical exploration, all required bowel resection. In follow-up, two patients died of intestinal necrosis and a third died of associated pancreatic cancer. Thirteen patients were discharged from the hospital. Treatment of coagulopathy was by heparin in three patients and sodium warfarin (Coumadin) in four patients. Long-term anticoagulation was not instituted because of gastrointestinal bleeding in three and cirrhosis in three patients. Mesenteric venous thrombosis can occur without gangrenous bowel. Diagnosis should be suspected when acute abdominal symptoms develop in patients with prior thrombotic episodes and a coagulopathy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1988

The demise of primary profundaplasty.

Although the importance of the profunda femoris artery in maintenance of lower extremity integrity was recognized in the earliest days of modern vascular surgery, disappointment with the performance of primary profundaplasty has emerged fully only in recent years. During the 10 year period from 1977 to 1987, only 17 patients were subjected to this procedure at Northwestern Memorial Hospital. The nine men and eight women averaged 65.6 years in age and exhibited the usual precursors of arterial insufficiency: a history of smoking in 12 patients (71 percent), clinical coronary artery disease in 8 patients (47 percent), hypertension in 7 patients, diabetes mellitus in 6 patients, hyperlipidemia in 2 patients, and uremia in 1 patient. Four patients exhibited hemodynamic improvement after profundaplasty (ankle-brachial index increase of greater than 0.15). Four required amputation postoperatively, and a fifth exhibited hemodynamic failure 9 months postoperatively and required amputation. Two patients required subsequent femoral-to-peroneal bypass to improve distal arterial perfusion. One patient died after the procedure, for a 5.9 percent mortality rate. Thus, the fact that profundaplasty has proved disappointing in the treatment of severe arterial insufficiency deserves emphasis at this time.

Adult↗

PubMed1987

The value of power frequency spectrum analysis in the identification of aortoiliac artery disease.

Prediction and localization of significant proximal occlusive disease in the lower extremities, whether in isolation or in combination with significant distal disease, still represent major problems to the noninvasive vascular laboratory. Power frequency spectrum analysis (PFSA) was done on continuous-wave Doppler signals in the common femoral artery of 86 limbs in 50 patients before and after postocclusive reactive hyperemia testing in an effort to differentiate hemodynamically significant from insignificant proximal occlusive disease, whether in isolation or in combination with hemodynamically significant distal disease. Limbs were assigned to four different categories according to their angiographic findings. With the use of a bandwidth at 50% peak amplitude (f50%) of 2000 Hz as the cut-off point between a positive and a negative examination, the test was 93% sensitive, 90% specific, and 92% accurate in distinguishing hemodynamically significant proximal lesions from hemodynamically insignificant lesions, regardless of distal disease. In addition, there exists a small group with significant disease at or close to the site of Doppler sampling, which produces f50% values of more than 3000 Hz. Diagnosis in this subgroup was much like that in carotid disorders. Finally, the predictive accuracy of standard noninvasive Doppler/segmental pressure measurement was compared with results of PFSA. In most patients, standard measurements were comparable; however, in the subgroup with hemodynamically significant proximal and distal disease, the PFSA technique accurately predicted hemodynamically significant proximal diseases in 93% of patients, where combined pressure/Doppler testing had an accuracy of only 61%. In all, spectrum analysis of common femoral artery velocity signals can greatly aid in determining the presence or absence of significant proximal disease in all situations.

Aorta, Abdominal↗

PubMed1986

Continuous-wave versus range-gated pulsed Doppler power frequency spectrum analysis in the detection of carotid arterial occlusive disease.

Two types of ultrasonic Doppler velocity metering devices currently used in the detection of extracranial carotid artery disease, the continuous-wave (CW) and the range-gated pulsed (RP) Doppler systems, were compared in the present study. Power frequency spectrum analysis (PFSA) was performed on 130 carotid arterial bifurcations with a CW Doppler and 81 carotid arteries with an RP Doppler system. All results were compared with angiographic findings. The frequency bandwidth at 50% peak power (f50%), a quantitative index for defining spectral broadening, detected stenoses equal to or greater than 50% diameter reduction with 93% sensitivity, 92% specificity, and 92% accuracy with the CW system. With the RP Doppler, the same degree of stenosis was identified with 94% sensitivity, 93% specificity, and 93% accuracy. Compared with angiographic classification into 0-24%, 25-49%, and 50-99% diameter reduction categories, CW Doppler PFSA and an 85% overall accuracy, and the RP Doppler overall accuracy was 86%. CW Doppler also correctly identified 15 of 16 internal carotid artery (ICA) occlusions; 8 of 8 ICA occlusions were correctly identified with the RP Doppler. Thus, both techniques detected carotid artery disease with comparable results. For research and ease of operation, an RP Doppler system with a variable sampling volume appears to be most desirable. However, a standard CW system is superior if utility and cost-effectiveness are of prime importance.

Arterial Occlusive Diseases↗

PubMed1985

Oxygen inhalation--induced transcutaneous PO2 changes as a predictor of amputation level.

Noninvasive transcutaneous PO2 (TcpO2) determinations have been developed to study peripheral arterial occlusive disease. To evaluate this technique as a predictor of amputation outcome, a blind, prospective study of 101 patients undergoing 119 amputations (23 above-knee [AK], 57 below-knee [BK], and 39 forefoot) was performed. TcpO2 measurements were obtained from the dorsum of the foot and 10 cm distal to the patella, both prior to and 10 minutes after inhalation of 100% oxygen. On the basis of preliminary results, initial TcpO2 values greater than 10 mm Hg or an increase greater than 10 mm Hg after oxygen inhalation were considered to predict a successful outcome, whereas failure was predicted when the initial TcpO2 value was less than 10 mm Hg and the increase after oxygen inhalation did not exceed the 10 mm Hg level. In the BK amputation group the test was 95% sensitive, 100% specific, and 95% accurate. Retrospective utilization of the above criteria in patients who had undergone both oxygen inhalation testing and AK amputation suggested that 9 of 17 limbs (53%) might have undergone a more distal BK amputation successfully. These results document the effectiveness of an initial TcpO2 determination coupled with the response to 100% oxygen inhalation as an excellent predictor of the outcome of lower extremity amputations.

Adult↗

PubMed1984

Posterior communicating artery visualization in predicting results of carotid endarterectomy for vertebrobasilar insufficiency.

Retrospectively, 51 patients who related two or more signs or symptoms of vertebrobasilar insufficiency and possessed concomitant carotid arterial disease were identified. The patient population was separated into two groups based on the presence or absence of an angiographically visualized posterior communicating artery during selective carotid artery injection. All patients had undergone unilateral or staged bilateral carotid endarterectomy. Comparison of postoperative clinical outcome with intracerebral angiographic findings exhibited statistically significant improvement in favor of those patients with at least one visualized posterior communicating artery. There was a greater likelihood of severe vertebral artery stenosis in those patients whose symptoms were not relieved by carotid endarterectomy.

Aged↗

PubMed1983

Natural history of asymptomatic ulcerative plaques of the carotid bifurcation.

In 79 patients with 91 asymptomatic ulcerating lesions of the carotid bifurcation who were followed an average of 54 months, there were two strokes, one of which was preceded by a warning transient ischemic attack. These data suggest that asymptomatic type A and type B carotid ulcerating lesions do not carry a significant early risk of stroke and do not warrant prophylactic carotid endarterectomy. However, the effect of antiplatelet drugs and anticoagulation in enhancing the development of subintimal hemorrhagic lesions remains uncertain. Further data with serial follow-up, preferably by noninvasive means, will be necessary to define the evolution of asymptomatic ulcerating carotid plaques and eventually permit identification of those lesions that have significant stroke potential.

Angiography↗

PubMedDate not supplied

Pneumonitis of unclear etiology in the surgical intensive care unit leading to the demise of an elderly, immunocompromised woman.

Multiple system organ failure, likely an expression of a dysregulated immune system, is a common cause of death in the surgical intensive care unit (ICU). While investigational modalities of therapy are on the horizon, current treatment primarily consists of supportive care. The case of an elderly woman who was admitted to the surgical ICU after a celiac axis-superior mesenteric artery bypass, is presented. Her course was complicated by Influenza-B pneumonitis, multiple system organ failure, and, ultimately, death. The course, pathophysiology, and therapeutic modalities involved in this syndrome are discussed. Additionally, the natural history of influenza infection is reviewed.

Aged↗

PubMedDate not supplied

Range-gated pulsed Doppler power frequency spectrum analysis for the diagnosis of carotid arterial occlusive disease.

Carotid arterial disease was investigated with a Duplex Scanner using Power Frequency Spectrum Analysis. Sixty-one carotid systems were evaluated noninvasively and angiographically, while 20 controls were examined and assumed to be normal. Peak frequency and 50% frequency bandwidth, a quantitative index of spectral broadening, were correlated with the percentage of stenosis. Peak frequency predicted the presence or absence of hemodynamically significant stenoses (greater than or equal to 50% diameter reduction) with 90.8% accuracy, while 50% frequency bandwidth correctly identified similar lesions with 93.2% accuracy (p = NS). Also, with the latter results, carotid systems were grouped into less than 25%, 25% to 49%, and greater than or equal to 50% stenosis categories with an 86.4% accuracy. Similar statistical evaluation was attempted for peak frequency results. It was not possible to separate hemodynamically insignificant lesions (less than 50% diameter reduction) into distinct groups because of the overlap of results among those arteries with less than 50% stenosis. Finally, all eight occluded internal carotid arteries were identified with combined Doppler/imaging analysis. However, with imaging alone, only 5 of 8 (63%) occluded arteries were correctly identified.

Carotid Artery Diseases↗