Biomedical subjects

W C Mackey

Publications and source records attributed to W C Mackey.

At least 37 records · Page 2Linked to original sources

PubMed1994

An assessment of the positive predictive value and cost-effectiveness of dipyridamole myocardial scintigraphy in patients undergoing vascular surgery.

PURPOSE: The approach to cardiac risk stratification of patients undergoing vascular surgery continues to be controversial. The success of algorithms that use clinical risk factors to determine cardiac risk have been inconsistent. Dipyridamole myocardial scintigraphy (DMS) has been accepted as a sensitive, noninvasive approach to risk stratification with excellent negative predictive value. Low positive predictive value (PPV) of abnormal DMS scans is a shortcoming that contributes to extensive preoperative cardiac evaluation and intervention with associated morbidity, mortality, and cost in most patients who undergo uncomplicated vascular procedures, regardless of DMS results. METHODS: Over 6 years, 237 patients underwent DMS before surgical management of infrarenal aortic aneurysm, aortoiliac, or infrainguinal occlusive disease. The value of multiple clinical factors and DMS were assessed retrospectively for the prediction of perioperative myocardial infarction (MI), heart-related death, or preoperative selection for myocardial revascularization. Only congestive heart failure and two or more reversible defects on DMS were statistically significant on logistic regression analysis. RESULTS: The PPV of DMS was 19% for all patients with reversible defects, 12% for patients with one reversible defect, and 36.7% for patients with two or more reversible defects. The rates of cardiac death and MI were 1.3% and 5.9%, respectively. Perioperative echocardiography revealed unchanged postinfarction ejection fraction in most patients who experienced MI. Cost-effectiveness of DMS screening was evaluated. CONCLUSIONS: The costs per MI and cardiac death averted suggest a decline in cost-effectiveness of screening with DMS over time, assuming improving cardioprotective strategies of patient care. Clinical risk factors were minimally useful in the prediction of perioperative MI, heart-related death, or need for myocardial revascularization. The PPV of DMS is low, and the majority of MIs may be clinically insignificant. The cost-effectiveness of cardiac screening with DMS may not be justifiable given current trends of health care reform.

Aged↗

PubMed1994

Are peroneal artery bypass grafts hemodynamically inferior to other tibial artery bypass grafts?

PURPOSE: Many authors have reported excellent long-term patency rates of peroneal artery bypasses. It has been suggested, however, that the hemodynamic result of the peroneal bypass is inferior to that of other infrapopliteal artery bypasses, making it suboptimal in patients with forefoot ischemic tissue loss. A retrospective review of 118 recent infrainguinal vein grafts (36 peroneal, 27 anterior tibial, 35 posterior tibial, 20 popliteal) was undertaken to assess and compare the hemodynamic results for each group. METHODS: We reviewed the hemodynamic results of 36 peroneal bypass grafts assessed by preoperative and postoperative ankle-brachial index and transmetatarsal pulse volume recording, duplex scan-derived distal graft peak systolic flow velocity, and intraoperatively measured outflow resistance. These results were compared with a concurrent series of anterior tibial, posterior tibial, and popliteal artery bypass grafts. All but one of the infrapopliteal bypass grafts were performed for limb salvage, and 65% of patients had ischemic ulcerations or gangrene. RESULTS: There was no difference in postoperative ankle-brachial index, postoperative transmetatarsal pulse volume recording, peak systolic flow velocity, or measured outflow resistance among the four different outflow groups. All patients with peroneal bypass grafts had healed wounds within a mean follow-up period of 17 months. There were no hemodynamic failures. CONCLUSION: Peroneal artery bypass grafts achieved hemodynamic results equivalent to anterior tibial, posterior tibial, and popliteal artery bypass grafts.

Analysis of Variance↗

PubMed1994

Gender dimorphism of a visual anomaly: a deductive prediction based on an ethological model.

Using an ethological model, we deduced a prediction concerning gender dimorphism in a visual anomaly from a re-construction of the phylogeny of man. The prediction, which is based on four premises, is that deficits in distance vision (myopia) would be more prevalent in contemporaneous women than in men. Data collected in a de facto double-blind method support the prediction, and thereby support the unique efficacy in using an ethological model to understand facets of the contemporary human condition.

Adult↗

PubMed1993

Superiority of balloon occlusion arteriography to reactive hyperemic arteriography in visualization of distal lower limb vessels.

Balloon occlusion arteriography was performed in 38 lower limbs; reactive hyperemic arteriography was also performed in 16 of these limbs. To assess the safety and utility of this technique the balloon occlusion arteriograms of all 38 patients were reviewed retrospectively by a vascular surgeon and vascular radiologist who were unaware of the patient's identity and ultimate treatment. After the arteriograms were reviewed and the outflow vessels identified, a decision was made regarding operability and optimal recipient vessel for distal bypass. Twenty-two of the 38 patients underwent balloon occlusion arteriography only, and 21/22 (95.5%) of these patients only had studies deemed adequate for surgical planning. Twelve of the 16 (75%) patients underwent both reactive hyperemic arteriography and balloon occlusion arteriography; potential distal outflow vessels not seen on reactive hyperemic arteriograms were observed on balloon occlusion arteriograms. In only 4/16 (25%) patients the balloon occlusion arteriograms did not yield additional information. No complications were associated with this technique. Approximately 8.5 g of iodine per run is used for balloon occlusion arteriography compared with approximately 37 g of iodine per run for reactive hyperemic arteriography. Balloon occlusion arteriography is a safe and accurate adjunctive technique that can be used when identification of lower limb vessels is critical.

Adolescent↗

PubMed1993

Transesophageal echocardiography for hemodynamic management of thoracoabdominal aneurysm repair.

Maintenance of cardiovascular stability during thoracoabdominal aneurysm repair remains a formidable challenge. Transesophageal echocardiography (TEE) has been shown to be an excellent method for detecting myocardial ischemia and assessing left ventricular volume. We examined the utility of TEE in a group of 17 patients from an overall series of 33 patients who underwent thoracoabdominal aneurysm resection between 1988 and 1992. The mortality rate was 9%, whereas the incidences of myocardial infarction and paraplegia were 13% and 6%, respectively. Intraoperative management was significantly altered by TEE data in nine patients. Two patients were noted to have mitral valve insufficiency, and one had transient ischemia-induced regional wall abnormalities. In six patients, Swan-Ganz-derived filling data failed to identify severe hemodynamic alterations that were noted on TEE. Five patients were hypovolemic and hyperdynamic, whereas one was in florid congestive heart failure. Further investigation is warranted to prospectively validate this technique.

Adult↗

PubMed1993

Marital dissolution by sex of the petitioner: a test of the man-child affiliative bond.

The problems in disentangling the tabula rasa explanations, as opposed to the biocultural explanations, in the understanding and prediction of human behavior are deep, real, and difficult. This study tested two conflicting sets of predictions concerning divorce patterns in the United States: a socioeconomic set and a biocultural set. The socio-economic perspective predicts that the addition of one or more children to a marriage would increase the husband's (as compared with the wife's) motivation to petition for a divorce. The biocultural perspective posits that a man-to-child affiliative bond would add to a man's adherence to his child(ren) and, in turn, would lower his motivation (as compared with the woman's) to petition for a divorce. The biocultural perspective was supported in this study.

Adult↗

PubMed1993

Long-term results of treatment for axillary subclavian vein thrombosis.

Thrombolytic therapy is an effective method for reopening an occluded venous segment, but little is known about the long-term results of thrombolysis via direct intravenous route for axillary subclavian vein thrombosis (ASVT). Our experience with 13 cases of primary ASVT illustrates the possible advantages of a protocol consisting of lytic therapy, surgical decompression and percutaneous balloon angioplasty if a high-grade stenosis persists. If accompanied by adjunctive therapy to correct the underlying cause, thrombolytic therapy for ASVT results in acceptable long-term symptom relief and vein patency.

Adult↗

PubMed1993

Common carotid artery occlusion with patent internal and external carotid arteries: diagnosis and surgical management.

PURPOSE: Occlusion of the common carotid artery (CCA) is generally associated with occlusion of the ipsilateral internal carotid artery (ICA) and external carotid artery (ECA). Occasionally, however, collateral circulation to the ECA may preserve patency of the ICA via retrograde perfusion through the bulb. These patients may suffer ongoing transient ischemic attacks and risk for stroke. Recognition of this pathologic variant may allow for effective surgical intervention. METHODS: We have performed seven operations in six patients with occluded CCAs and patent ECA and ICAs. The occluded CCA was on the left side in each case (p < 0.01). Six of the operations were performed for ischemic symptoms, including amaurosis fugax in five patients, hemispheric TIA in one patient, and profound global ischemia in two patients who had concomitant occlusions of other extracranial vessels. In the five most recent cases the patent ECA and ICA above the occluded CCA were recognized by preoperative duplex scanning, which prompted cerebral angiography. A variety of reconstructive procedures were used, depending on the pathologic anatomy. These procedures included subclavian or axillary artery to carotid artery bypass with carotid endarterectomy (five), carotid endarterectomy with thrombectomy of the proximal CCA (one), and ascending aorta to carotid artery bypass (one). RESULTS: There were no strokes associated with the surgery, although one patient had transient neurologic symptoms and a seizure associated with documented reperfusion edema. Three of the patients had preoperative and postoperative transcranial Doppler studies that documented significant improvement in intracranial hemodynamics. Five of the patients have had continuously patent grafts with relief of symptoms for an average of 40 months (range 3 to 155 months). The remaining patient had graft occlusion after 72 months and underwent repeat operation for amaurosis fugax and global ischemia. His second graft remains patent, and he is symptom free 21 months later. CONCLUSIONS: Recognition of patent distal vessels above a CCA occlusion depends on a high index of suspicion, careful investigation of the carotid bulb with duplex scanning, and delayed arteriographic views of the bulb allowing for late collateral vessel filling. The favorable results in this small series of patients supports an aggressive surgical approach when patients with symptoms are encountered with patent distal vessels above an occluded CCA.

Aged↗

PubMed1992

The effect of suprarenal cross-clamping on abdominal aortic aneurysm repair.

Two hundred five patients who underwent elective abdominal aortic aneurysm repair were divided into two groups: those who underwent infrarenal cross-clamping alone (n = 166) and those who underwent suprarenal cross-clamping alone or combined with infrarenal cross-clamping (n = 39). Mortality was comparable between groups (1.2% for infrarenal cross-clamping vs 2.6% for suprarenal cross-clamping). Transient renal insufficiency was more frequent in the suprarenal group than in the infrarenal group (28% vs 10%), but dialysis rates (3% for suprarenal vs 2% for infrarenal) were similar. Cardiac morbidity was comparable between groups as well. Operating room data reflected the technical challenge of complex aneurysm repairs. The retroperitoneal approach was the preferred exposure in the suprarenal group since better access to the suprarenal aorta may be achieved with this technique. While abdominal aortic aneurysm repairs requiring suprarenal cross-clamping remain a technical challenge, the risks are not formidable and suprarenal cross-clamping should be considered when confronted with difficult periaortic dissection.

Academic Medical Centers↗

PubMed1992

Clinical and hemodynamic results of bypass to isolated tibial artery segments for ischemic ulceration of the foot.

Patients with ischemic ulceration of the foot and no continuous tibial or inframalleolar vessels acceptable for bypass are often treated with primary amputation. We have performed autogenous vein bypass to isolated tibial artery segments (ITAS) in nine patients with ischemic foot ulcers and no other outflow options. We reviewed the clinical and hemodynamic results of these bypasses to assess the efficacy of this approach. Hemodynamic comparisons of these ITAS bypasses were made to a concurrent series of 26 bypasses to intact tibial arteries and 24 inframalleolar artery bypasses assessed during routine follow-up. Eight of the bypasses originated from the above-knee popliteal artery and one from the profunda femoris artery. Recipient vessels were the anterior tibial (seven), peroneal (one), and posterior tibial (one) arteries. Although mean ankle brachial indices (ABI) increased significantly from 0.26 +/- 0.06 preoperatively to 0.75 +/- 0.04 postoperatively (p = 0.0015), ITAS bypass patients had lower mean postoperative ABIs than patients with bypasses to intact tibial (ABI = 0.98 +/- 0.03, p = 0.0001) or pedal arteries (ABI = 1.02 +/- 0.04, p = 0.0005). Similarly, duplex scan-derived peak systolic flow velocities of the ITAS bypasses (mean: 52.9 +/- 5.8 cm/sec) were lower than those of intact tibial artery bypasses (mean: 80.1 +/- 6.1 cm/sec, p = 0.02) but did not differ from those of pedal bypasses (mean: 59.5 +/- 3.5 cm/sec, p = 0.34). No ITAS bypass grafts have failed during a mean follow-up of 12.3 +/- 2.7 months. Although wound healing was prolonged (mean: 3.1 +/- 0.6 months), the wounds of eight of nine patients eventually healed, with three patients requiring minor amputations (one digital amputation and two transmetatarsal amputations). Although the hemodynamic results of ITAS bypass are inferior to those of more conventional bypasses, the early patency rates and successful healing of ischemic wounds confirm that it is a valid alternative in the threatened limb with no other outflow options.

Aged↗

PubMed1992

The variation in vein graft flow velocity with luminal diameter and outflow level.

Duplex scanning has recently been used to monitor the patency of infrainguinal vein grafts. Empirically derived criteria that have been used for identifying the failing graft have never accounted for the effect of vein graft diameter or varying outflow resistance, despite the fact that they are major determinants of flow. We prospectively examined the variation in graft peak systolic flow velocity with graft diameter and outflow level in a consecutive series of 68 patients with 72 normally functioning vein grafts returning for routine follow-up. Images were obtained of vein grafts with a duplex scanner throughout their lengths, and the distal peak systolic flow velocity and intraluminal diameters were recorded. There were 15 popliteal, 26 tibial, and 21 inframalleolar grafts. The mean ankle-brachial index of inframalleolar grafts was 1.01 +/- 0.04 and did not differ significantly from tibial (0.96 +/- 0.03) or popliteal (0.93 +/- 0.06) grafts (p = 0.32). Grafts to the three outflow levels differed significantly in diameter, with inframalleolar grafts measuring 3.95 +/- 0.17 mm, tibial grafts 4.78 +/- 0.21 mm, and popliteal grafts 5.65 +/- 0.38 mm (p = 0.0001). In a similar manner inframalleolar grafts had significantly lower peak systolic flow velocities (59.1 +/- 3.4 cm/sec) than tibial (77.2 +/- 5.6 cm/sec) or popliteal (71.0 +/- 7.6 cm/sec) grafts (p = 0.04). Inframalleolar grafts did not demonstrate a significant correlation (r = -0.21, p = 0.29) between peak systolic flow velocity and graft diameter. Conversely, both tibial (r = -0.49, p = 0.005) and popliteal (r = -0.73, p = 0.002) grafts demonstrated significant inverse correlations.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1992

Late stroke after carotid endarterectomy: the role of recurrent stenosis.

Perioperative stroke after carotid endarterectomy has been well studied, although little information is available regarding later strokes. We determined the etiology of late stroke after carotid endarterectomy by examining the records of those patients in our carotid registry who had a stroke more than 30 days after surgery. Thirty-five (5.1%) of the 688 patients in our registry had a stroke more than 30 days after surgery (mean follow-up, 59.3 months; standard error, 1.8 months; range, 1 to 292 months). The cause of late stroke was established by input from consulting neurologists, CT scanning of the head, magnetic resonance imaging results, angiograms, noninvasive studies, and postmortem examinations. Eight of the 11 strokes of unknown origin were massive fatal events for which no further evaluation was undertaken. Restenosis or occlusion accounted for fewer strokes (3 of 20, 15%) in the 1- to 36-month postoperative interval than in the greater than 36-month interval (8 of 15, 53.7%) (p less than 0.02 by Fisher's Exact Test). These data support the hypothesis that the early pseudointimal hyperplastic lesion is less likely to result in stroke than is later recurrent stenosis, which is usually related to atherosclerosis.

Arteriosclerosis↗

PubMed1992

Routine postendarterectomy duplex surveillance: does it prevent late stroke?

Our recent finding that less than 50% of late postendarterectomy strokes are related to recurrent carotid stenosis led us to question the utility of routine postendarterectomy duplex surveillance (RpCEADS) in the prevention of late stroke. To evaluate our RpCEADS program, we reviewed our postoperative duplex studies and correlated their results with clinical data. A total of 1053 postendarterectomy scans was carried out on 348 carotid arteries (258 patients) (3.0 +/- 0.1 studies/artery) during an average follow-up of 52.6 (+/- 2.3) months. Less than 50% of recurrent carotid stenosis was documented throughout follow-up in 292 (83.9%) of 348 arteries. Recurrent carotid stenosis of greater than 50% or occlusion of either the common or internal carotid artery was noted in the remaining 56 arteries (16.1%). Of the 56 duplex-detected recurrent stenoses, only two (3.6%) resulted directly in an unheralded stroke, whereas eight (14.3%) underwent prophylactic reoperation, eight (14.3%) resulted in transient ischemia requiring reoperation, eight (14.3%) occluded without causing stroke, and 29 (51.8%) remained asymptomatic and did not progress to occlusion. Assuming that each of our eight patients who underwent prophylactic reoperation would have had a stroke if operation had not been carried out and our two unheralded strokes could have been prevented with more rigorous follow-up, RpCEADS might have prevented late stroke related to 10 (2.9%) of 348 arteries in 10 (3.9%) of 258 patients after surgery. All other cases of duplex-detected recurrent carotid stenosis or occlusion were asymptomatic or manifest by transient cerebral ischemia. Therefore RpCEADS cannot be justified as a means of preventing late strokes related to recurrent stenosis.

Carotid Stenosis↗

PubMed1991

Long-term follow-up of patients operated on for recurrent carotid stenosis.

We reviewed our experience with 29 operations for recurrent carotid stenosis in 27 patients who underwent both their primary carotid endarterectomy and their reoperations at our institution. These 27 patients represent 4% of the 667 patients who underwent primary carotid endarterectomies at our institution and who are included in our carotid follow-up registry. Reoperation was prompted by recurrent symptoms in 19/29 (65.5%) cases. Comparison of long-term stroke prevention in those patients who did (84% at 5 years, 78.6% at 10 years) and did not (90.3% at 5 years, 83.6% at 10 years) develop recurrent stenosis requiring reoperation revealed no statistically significant difference (p = 0.48) when measured from the time of primary operation. The perioperative stroke and death rates for reoperation (3.4% and 0%) were acceptable. We conclude that with our acceptably low perioperative stroke morbidity (3.4%), surgery for recurrent carotid stenosis in symptomatic patients or in asymptomatic patients with high-grade (greater than or equal to 75%) stenosis maintains the durable stroke prevention offered by primary carotid endarterectomy.

Carotid Arteries↗

PubMed1991

The economic implications of high-risk abdominal aortic aneurysms.

Financial data of 102 patients undergoing elective and emergent abdominal aortic aneurysm repair over a 3-year period were evaluated in terms of postoperative length of stay, net revenue, total standard cost, and net margin. Cost reimbursement was based on diagnosis related group payments. Aneurysm repairs were classified as emergent, high-risk elective, or low-risk elective. A net loss of $409,459 was noted for the entire series. Emergent repairs, although only 12% of the population, accounted for 73% of total losses, with a mean loss of $24,655/patient. The mean net loss in the high-risk elective group was $3590/patient, and a net gain of $1132/patient was noted in the low-risk elective group. Length of stay outliers, defined as length of stay greater than 28 days, contributed to the bulk of the losses in the elective series and were predominant in the high-risk group. No preoperative comorbidity, other than high-risk classification, predicted outlier status. Length of stay correlated with total standard costs in all categories of aneurysm repair. Third party payment for length of stay outliers was inadequate; the diagnosis related group system warrants revision so that outlier reimbursement will be based on a tiered system derived from length of stay.

Aorta, Abdominal↗

PubMed1991

Optimum results of the surgical treatment of carotid territory ischemia.

Continuing controversy over the role of carotid endarterectomy in stroke prevention is based largely on reports in which high perioperative morbidity and mortality rates obviate possible long-term benefit from the procedure. The purpose of this review is to examine optimal results of carotid surgery in order to describe the potential for the procedure in stroke prevention. Optimal surgical results are compared with optimal medical results in the therapy of symptomatic patients and with optimal nonsurgical results in the therapy of asymptomatic patients. Factors common to series with excellent results, such as patient selection and operative technique, are examined, and problems such as recurrent carotid stenosis and coexisting coronary disease, which continue to plague even the best surgical series, are discussed.

Carotid Arteries↗

PubMed1990

Cardiac risk in patients undergoing carotid endarterectomy: impact on perioperative and long-term mortality.

To identify patients undergoing carotid endarterectomy who are at high risk for cardiac events and death, we studied the course of 614 patients with known risk factors who were entered into our carotid follow-up registry. Patients were divided into two groups, group I with overt coronary disease (prior myocardial infarction, angina, significant electrocardiographic abnormalities) (N = 324) and group II without overt coronary disease (N = 290). Group II patients were subdivided into groups with (IIA) (N = 206) and without (IIB) (N = 84) coronary risk factors (cigarettes, diabetes, or hyperlipidemias). Thirty-day, 5-, 10-, and 15-year life-table survival for the groups was: I = 98.5%, 68.6%, 44.9%, 36.4%, respectively; II = 100%, 86.4%, 72.3%, 54.3%, respectively; IIA = 100%, 84.8%, 66.9%, 41.5%, respectively; IIB = 100%, 90.5%, 87.9%, 87.9%, respectively. Overt coronary disease was associated with diminished 30-day (p = 0.03) and late (p less than 0.0001) survival. Risk factors in the absence of overt disease were not associated with diminished 30-day survival. Late survival up to 3 years from endarterectomy was similar in groups IIA and IIB, but later survival was diminished in group IIA. Myocardial infarction was the most frequent cause of death in all groups. Patients with overt coronary disease are at high risk for late cardiac events and death. Patients without overt disease are at less risk than those with overt disease, and in the absence of overt disease, those without are at less risk than those with risk factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗

PubMed1990

Comparison of ejection fraction and Goldman risk factor analysis to dipyridamole-thallium 201 studies in the evaluation of cardiac morbidity after aortic aneurysm surgery.

Associated coronary artery disease is the critical factor that influences early and late mortality after abdominal aortic aneurysm surgery. Dipyridamole-thallium 201 scintigraphy, left ventricular ejection fraction, and Goldman risk factor analysis have been suggested as preoperative noninvasive screening methods to detect significant coronary artery disease. In this series of 95 elective abdominal aortic aneurysm repairs dipyridamole-thallium 201 scintigraphy was highly predictive of the absence of perioperative cardiac morbidity (96% specificity, 44/46 normal scans, no cardiac morbidity), whereas ejection fraction (73% specificity, 31/42 normal ejection fraction, no cardiac morbidity) and Goldman risk factor analysis (84% specificity, 44/51 class I, no cardiac morbidity) were less. Furthermore, thallium redistribution on dipyridamole-thallium 201 scintigraphy leading to coronary angiography identified a significant number of patients with occult coronary artery disease who required preoperative coronary revascularization (8%, 8/95) and might have remained undetected on the basis of left ventricular ejection fraction or Goldman risk factor analysis. Finally, fixed thallium deficit, which some investigators have interpreted as a low probability finding for cardiac morbidity, was associated with a higher than expected incidence of cardiac complications. Forty-six percent (7/15) of all postoperative cardiac complications (three myocardial infarctions, three ischemic events, one death) occurred in patients with abdominal aortic aneurysms with fixed deficits. This suggests that patients with fixed deficits on dipyridamole-thallium 201 scintigraphy should be considered for later "delayed" (4 hours) thallium images or coronary angiography or both.

Aged↗