Prospective study of the value of prebypass saphenous vein angioscopy

BACKGROUND

The patency of a saphenous vein graft is directly related to the quality of the vein harvested. Thus, appropriate evaluation of the vein before implanting it as a bypass graft may help identify those veins at high risk for early failure. Accordingly, we prospectively investigated whether prebypass angioscopic assessment of the saphenous vein could identify those vein grafts at particularly high risk of early failure.

PATIENTS AND METHODS

Thirty-two greater saphenous veins with a grossly normal appearance were evaluated angioscopically before their use as a bypass conduit. After modification of abnormal segments, all of the veins irrigated well and were used as bypass grafts.

RESULTS

Twenty-four patients were available for follow-up at 12 months. Seventeen (71%) had been prospectively classified as having angioscopically normal saphenous veins, while 7 were identified as having abnormal veins. The two groups did not differ significantly in demographics, cardiovascular risk factors, or indications for operative intervention. Twelve of the 17 (70%) normal veins were patent at 1 year; however, only 1 (14%) of the angioscopically abnormal vein grafts remained patent for 12 months (chi-square = 4.27; P = 0.039).

CONCLUSION

Angioscopic inspection of the saphenous vein, before insertion as a graft, allows for identification of unrecognized venous disease that portends early graft thrombosis. Exclusion of abnormal veins, based on an abnormal angioscopic appearance, may lead to improved results for lower-extremity revascularization procedures; this supports the value of vein-graft angioscopy.

Transseptal defibrillation is superior for transvenous defibrillation

The conventional electrode configuration of current internal defibrillation systems most commonly use superior vena caval (SVC) or combined SVC and subcutaneous (SC) electrodes as anode, and right ventricular apex (RVA) electrode as cathode. We have demonstrated earlier that the septal mass is important for defibrillation. The purpose of the present study was to compare a transseptal to a conventional electrode arrangement in the canine model. Three endocardial electrodes, 5 French EnGuard were positioned in RVA, SVC, and the right ventricular outflow (RVO) in eight dogs. A 5 French SC electrode was positioned in the fifth left intercostal space. RVA-RVO-/SC+ (configuration 2) was compared to SVC-SC+/RVA- (configuration 1). Defibrillation threshold testing was performed using asymmetrical biphasic shock, 6 msec+/2 msec-. Probit fit was used to compare the results at 40%, 50%, 60%, and 90% probabilities, and the logistic regression analysis to estimate the impact of variables. Electrode configuration had the strongest predictive value. Configuration 2 was superior to configuration 1 (P = 0.0016). At any voltage settings the probability of success for configuration 2 was greater, and current less (P < 0.00005). The energy requirements were reduced by approximately 33% for configuration 2. There were no significant differences in impedance between the two configurations. We conclude that transseptal defibrillation is more effective because of the improved lead geometry and voltage gradient.

Health care's power brokers in the 21st Century. Interview by Donna Vavala

Health care has undergone turbulent change in the 20th Century. In addition to dramatic pharmaceutical and technological advances, the entire health care delivery system has been significantly improved. Through all the turmoil, hospitals have been at the center of the health care universe. But, as the 21st Century approaches, that may change, too. What will become of hospitals, which for most of this century have played a commanding role? Will managed care organizations and group practices come out on top? And, once the new power broker takes over, what will be the impact on providers, insurers, and the government, and how will their relationships to each other change? Jeff Goldsmith, PhD, President of Health Futures, Inc., Bannockburn, Ill., and health care futurist, examines tomorrow's health care delivery system and makes some eye-opening predictions.

Electrode surface area is an important variable for defibrillation

Previous studies have established efficacy of transseptal defibrillation. The purpose of the present study was to evaluate the role of transvenous electrode surface area for defibrillation. Sixteen dogs were randomized to 8 French and 5 French EnGuard electrodes; 8 dogs in each group. The length of the defibrillation coils was identical for both, but the surface area was different due to differences in the electrode diameters. Defibrillation threshold (DFT) testing was performed using a biphasic shock waveform, 6 msec+/2msec-. Logistic regression analysis was used to determine if the probability of defibrillation adjusted for voltage, current, and energy was different for 8 French electrodes. Logistic regression analysis found significant differences between 8 French and 5 French electrodes, with less voltage (P < 0.005), current (P < 0.03), and energy (P < 0.001) required at any level of probability to defibrillate for 8 French electrodes. These results support the conclusion that the surface area for endocardial electrodes is a significant factor for defibrillation. Therefore, when designing endocardial electrodes a desirable objective of reducing the electrode size should be weighed against the need to minimize DFTs.

Squamous cell carcinoma antigen: clinical utility in squamous cell carcinoma of the uterine cervix

This study further defines the clinical utility of squamous cell carcinoma antigen (SCC-Ag) in initial squamous carcinoma of the cervix, response to treatment, and in the detection of recurrence. Serum specimens were drawn and analyzed from patients with squamous cell carcinoma. Charts were reviewed on 272 patients with 1053 samples evaluated. Treatment of patients prior to the availability of the assay and patients lost to follow-up resulted in lower total numbers of initial and recurrent values. Data were analyzed to detect trends during and after treatment. All values at or above the lowest detectable level of antigen were included; that is, 1.5 ng/ml and above. A SCC-Ag value > or = 2.0 ng/ml drawn at any time during the disease process has a 96.3% positive predictive value, while a value < 2.0 ng/ml is 97.2% specific for absence of disease. Fifty-three percent of 103 patients had elevated SCC-Ag levels prior to treatment, with the proportion increasing accordingly with advancing stage at diagnosis. In 70 patients with recurrence, 81% had elevated values. Squamous cell carcinoma antigen predicted recurrence an average of 6.9 months prior to detection of clinically evident disease. Patients with initially negative SCC-Ag levels may demonstrate elevated values with tumor recurrence. This marker accurately reflects the response to treatment in patients who have elevated levels prior to treatment. Squamous cell carcinoma antigen is a useful tumor marker in the management of patients with squamous cell carcinoma of the uterine cervix.

Selective preservation of infected prosthetic arterial grafts. Analysis of a 20-year experience with 120 extracavitary-infected grafts

OBJECTIVE

The authors report on their 20-year experience with 120 patients with infected extracavitary prosthetic arterial grafts (95 polytetraflouroethylene, 25 Dacron). Throughout this experience, an effort was made, when appropriate, to salvage all or a portion of these infected grafts.

METHODS

When patients had arterial bleeding (20 cases) or systemic sepsis (6 cases), immediate graft excision was performed. When the infected graft was occluded (43 cases), subtotal graft excision was performed, leaving an oversewn 2- to 3-mm graft remnant to maintain patency of the artery. Complete graft preservation was attempted in 51 cases in which the graft was patent, the patient was not septic, and the anastomoses were intact. Aggressive operative wound debridement was repeated, as necessary, to achieve wound healing. The preferred method of revascularization, when necessary, included secondary bypasses tunneled through uninfected (often lateral) routes. Follow-up averaged 3 years (range, 1 month-20 years).

RESULTS

This strategy resulted in a hospital mortality of 12% (14/120) and a hospital amputation rate in survivors of 13% (14/106 threatened limbs). Of the surviving patients treated by complete graft preservation, the hospital amputation rate was only 4% (2/45) and long-term complete graft preservation was successful in 71% (32/45) of cases. Partial graft preservation also proved successful in 85% (35/41) of surviving patients who had occluded grafts. Successful complete graft preservation was as likely when gram-negative or gram-positive bacteria were cultured from the wound, with the exception of Pseudomonas (successful graft preservation in only 40% [4/10] of cases).

CONCLUSION

Based on this 20-year experience, the authors conclude that selective partial or complete graft preservation represents a simpler and better method of managing infected extracavitary prosthetic grafts than routine total graft excision.

Eleven-year experience with tibiotibial bypass: an unusual but effective solution to distal tibial artery occlusive disease and limited autologous vein

PURPOSE

The absence of sufficient length of suitable autologous vein occasionally prohibits the treatment of severe distal lower extremity arterial occlusive disease with a standard distal bypass originating from the common femoral artery. During the past 11 years, we have therefore selectively performed short distal bypasses originating from the infrapopliteal arteries in patients with limb-threatening ischemia and occlusive lesions limited to the distal tibial and peroneal arteries. This report summarizes our experience with these tibial artery based distal bypasses.

METHODS

Forty-two distal lower extremity arterial bypasses originating from infrapopliteal arteries in 41 patients were performed over an 11-year period. Autologous vein was used as the bypass conduit in all cases. Extensions from a more proximal bypass were excluded.

RESULTS

The primary patency rate of these tibiotibial bypasses was 77% at 1 year and 62% after 5 years. The limb salvage rate after 5 years was 74%. The perioperative mortality rate was low (2%), but the 5-year patient survival rate (64%) was similar to that with more standard lower extremity arterial reconstructive procedures.

CONCLUSIONS

Tibiotibial bypass is an effective limb salvage procedure in carefully selected patients with distal tibial artery occlusive disease and limited autologous vein. It offers a durable means of distal revascularization in circumstances in which a standard operation might not be desirable or possible.

Pharmacokinetic evaluation of the combination of zidovudine and didanosine in children with human immunodeficiency virus infection

As part of a phase I/II trial in children infected with human immunodeficiency virus, we studied the pharmacokinetics of zidovudine and didanosine administered as single agents and in combination. Zidovudine (60 to 180 mg/m2 per dose) was given orally every 6 hours, and didanosine (60 to 180 mg/m2 per dose) every 12 hours. Pharmacokinetic samples were obtained from 54 patients and the area under the plasma concentration-time curve (AUC) was estimated by means of a previously defined limited sampling strategy. Follow-up blood samples were obtained after 4 and 12 weeks of treatment. The mean AUC for zidovudine ranged from 4.8 mumol.hr per liter at 60 mg/m2 to 11.0 mumol.hr per liter at the 180 mg/m2 level, and increased in proportion to the dose. The mean AUC for didanosine ranged from 2.8 mumol.hr per liter (60 mg/m2) to 8.0 mumol.hr per liter (180 mg/m2), with a wide interpatient variability. The AUCs of zidovudine and didanosine remained unchanged when the agents were administered in combination. There was no significant change in the AUCs of either drug after 4 and 12 weeks in comparison with those on day 3 of therapy. However, there was greater interpatient and intrapatient variability with didanosine than with zidovudine. These observations have implications for the future utility of therapeutic drug monitoring with these agents.

Effects of inhaled NO and inhibition of endogenous NO synthesis in oxidant-induced acute lung injury

Inhaled nitric oxide (NO) decreases pulmonary arterial pressure (Ppa) and improves oxygenation in the adult respiratory distress syndrome. Endogenous NO can modulate the development of acute tissue injury. We investigated the effects of inhaled NO and of inhibition of endogenous NO synthase in oxidant-induced acute lung injury in the isolated buffer-perfused rabbit lung. A rapid (45 min) and a more gradual (3 h) model of oxidant-induced acute lung injury were developed using the production of superoxide free radicals from the reaction of purine with low and high doses of xanthine oxidase, respectively. The effects of rapid injury included increases in Ppa, precapillary pulmonary vascular resistance, capillary filtration coefficient (Kfc), and lung weight. In the gradual-injury model, only lung weight and Kfc increased. Pretreatment with inhaled NO (90-120 ppm) prevented the rise in Ppa and precapillary pulmonary vascular resistance in the rapid-injury model and prevented elevation of Kfc in the gradual-injury model. Pretreatment with an inhibitor of endogenous NO synthase (NG-nitro-L-arginine methyl ester) resulted in increased pulmonary capillary pressure and postcapillary pulmonary vascular resistance in the rapid-injury model and increased peak Ppa, pulmonary capillary pressure, and pulmonary vascular resistance in the gradual-injury model. These data suggest that in oxidant-induced acute lung injury 1) inhaled NO may attenuate increases in capillary permeability and 2) endogenous NO may function as a modulator of pulmonary vascular tone without affecting capillary permeability.

Management of arterial injuries produced by percutaneous femoral procedures

BACKGROUND

A significant number of vascular injuries occur with the use of percutaneous diagnostic and therapeutic procedures. This study was done to indicate the types of these injuries and their management.

METHODS

Over a 30-month period, 55 patients required operation for vascular complications after percutaneous femoral procedures including infrarenal arteriography (six patients) and angioplasty (22 patients), coronary angiography (16 patients) and angioplasty (five patients), and aortic balloon pump insertion (six patients).

RESULTS

The 14 iliac and 41 femoral artery injuries included 29 pseudoaneurysms, six lacerations with persistent bleeding, seven dissections, six occlusions, three ruptures, two arteriovenous fistulas, and two large hematomas. Control for all femoral and distal external iliac artery lesions was obtained solely through a groin incision in 45 (82%) patients. Our technique for exposure of the external iliac artery through the groin is described. A separate retroperitoneal incision was necessary in 10 patients because of proximal injury, massive pseudoaneurysm, morbid obesity, or heavily scarred groins. In this series 34 lateral suture repairs, 11 interposition or bypass grafts, four patch angioplasties, one endarterectomy, three thrombectomies, and two hematoma evacuations were performed. Although no limb loss occurred, we encountered nine wound complications, five myocardial infarctions, and two deaths.

CONCLUSIONS

This experience shows the wide variety of vascular complications caused by percutaneous procedures and the different techniques necessary for their management.

Management of infected lower extremity autologous vein grafts by selective graft preservation

Between 1975 and 1991, we treated 16 patients with infected lower extremity autologous vein grafts performed for limb salvage by complete graft preservation. Traditional treatment of these infections includes immediate graft excision and complex revascularization procedures to prevent limb loss. The infection involved an intact anastomosis in 12 patients or the body of a patent graft in 4 patients. None of the patients was systemically septic. All patients were treated with appropriate intravenous antibiotics. Six patients were treated by placement of autologous tissue on the exposed graft (4 rotational muscle flaps, 2 skin grafts), and 10 were treated with antibiotic-soaked dressing changes and repeated operative débridements to achieve delayed secondary wound healing. This treatment resulted in a 19% (3 of 16) mortality rate and an 8% (1 of 13) amputation rate in survivors. Of the six patients managed by autologous tissue placement onto the infected graft, five patients had wounds that healed without complications, and one died of a myocardial infarction. Of the 10 patients treated by delayed secondary wound healing, 2 developed anastomotic hemorrhage, which resulted in death in 1 patient and above-knee amputation in the other, 1 died of a myocardial infarction, 1 developed graft thrombosis, and 6 had wounds that healed. Placement of autologous tissue to cover an exposed, infected patent vein graft with intact anastomoses may prevent graft dessication, disruption, and thrombosis, which renders graft preservation an easier, safer method of treatment compared with routine graft excision.

Limb salvage surgery in end stage renal disease: is it worthwhile?

The role of limb salvage surgery in patients with end stage renal disease (ESRD) is controversial. In view of this debate, we reviewed our experience with 54 primary and 15 secondary revascularizations for limb salvage in patients with ESRD over the past decade. Thirty-seven patients required dialysis and 10 had functioning renal transplants. Severe limb threatening ischemia was the indication for all revascularizations. The 2-year cumulative secondary graft patency rate was 56.2% with an associated limb salvage rate of 71.4%. There was no significant difference in graft patency or limb salvage rates between patients requiring dialysis and those with functioning renal allografts (p = 0.5). The 30-day operative mortality for the 99 surgical procedures (69 arterial bypasses and 30 additional operations) was 13% and the 2-year patient survival was 45.6%. Six of the 15 amputations were performed despite a patent graft on limbs which had extensive infection and gangrene. We conclude that limb salvage surgery should only be undertaken with recognition of these risks in patients with ESRD or functioning renal transplants. Surgery should be performed before gangrene and infection become extensive. Patients with unrelenting infection or mid-forefoot gangrene should be considered for primary amputation.

Unsuspected preexisting saphenous vein disease: an unrecognized cause of vein bypass failure

Our prior anecdotal experience with unsuspected preexisting saphenous vein disease prompted us to study its incidence, its relation to graft failure, and to identify techniques for its detection. Thick-walled, postphlebitic sclerotic occluded, postphlebitic sclerotic recanalized, calcified, and varicose vein lesions were detected in 63 (12%) of 513 infrainguinal vein bypasses. In 13 (2% to 5%) cases, severe saphenous vein disease precluded use of the vein. In the remaining 50 cases, the entire vein or a portion thereof, with minimal or unsuspected disease, was used for bypass. Early graft failures occurred in 10 (20%) of the 50 cases. The cumulative primary patency rate at 30 months for bypasses performed with diseased veins was 32%. This was significantly less than the 73% cumulative primary patency rate for bypasses with veins without detectable disease (p less than or equal to 0.001). Retrospective evaluation of preoperative duplex ultrasonography (n = 21) originally used to evaluate saphenous vein length and diameter correctly identified thick-walled, occluded, calcified, and varicose veins in 62% of cases. Intraoperative methods of vein evaluation included inspection, palpation, irrigation, catheter or valvulotome insertion to identify obstruction, and intraoperative arteriography. Histologic examination of diseased veins demonstrated a spectrum of disease with thickening of the intima and media, vein wall calcification, and luminal recanalization. We conclude that (1) unsuspected preexisting saphenous vein disease occurs in approximately 12% of cases and results in both early and late graft failures; (2) detection, in some cases, is possible with duplex ultrasonography and intraoperative techniques; and (3) diseased veins that are recanalized, calcified, or thick-walled should not be used if an alternative vein is available.

A ten-year experience with one hundred fifty failing or threatened vein and polytetrafluoroethylene arterial bypass grafts

Between Jan. 1, 1980, and Dec. 31, 1989, 2187 infrainguinal revascularization procedures were performed. In 130 of these cases with patent bypasses, hemodynamic deterioration was suspected, and urgent arteriography was performed. Twenty additional patients with aortofemoral, femorofemoral, or axillofemoral bypasses demonstrated hemodynamic deterioration. In 93% of failing grafts the condition was suspected because of recurrent symptoms or changes in the pulse examination. Two hundred eighty-five high-grade stenotic or occlusive lesions were identified in inflow arteries, outflow arteries, within the graft, or at proximal or distal anastomoses associated with these 150 grafts. One hundred sixty-one (57%) of these lesions were in patients with failing vein grafts; 115 (40%) were in patients with failing polytetrafluoroethylene (PTFE) grafts; and 9 (3%) were associated with failing composite vein/PTFE grafts. Stenotic lesions less than 5 cm in length were initially treated with percutaneous transluminal balloon angioplasty (PTA). Occlusive lesions, stenoses greater than 5 cm in length, and PTA failures were treated surgically. The overall 6-year cumulative secondary patency rate for failing grafts was 65%, and the limb salvage rate was 75%. The extended patency rate after the first intervention in the failing state was 56% at 5 years. The 5-year secondary patency rate for grafts initially treated with PTA (58%) was not significantly different (p = 0.25) from that for grafts treated initially with surgery (71%). Percutaneous transluminal angioplasty was effective for inflow stenoses of the iliac, femoral, and popliteal arteries and for some outflow lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

When wanderlust takes over. Nurse-run foreign travel clinics

As more people travel abroad to exotic locations, the need for vaccinations and advice is growing. Nurses based in GP practices and health centres can provide a convenient and comprehensive service.

The need for quality assurance in vascular surgery

The need for quality assurance in vascular surgery can be deduced from the variability in unruptured abdominal aneurysm operative death rates in a group of patients large enough that factors influencing mortality rates other than quality of care can be controlled. Operative mortality rate for 3570 patients undergoing unruptured abdominal aortic aneurysm repair was determined for all non-Veterans Administration surgeons and hospitals in New York State from 1985 to 1987. The average annual number of aneurysm operations per surgeon was 3.6, and per hospital it was 10.2. Unruptured aneurysm repair mortality for surgeons performing 1 to 5 aneurysm operations per year was 10% whereas for surgeons performing more than 26 aneurysm operations per year it was 6% (p less than 0.0001). Unruptured aneurysm repair mortality for hospitals performing 1 to 5 aneurysm operations per year was 14% and for hospitals performing more than 38 aneurysm operations per year it was 5% (p less than 0.0001). Even when these mortality rates were adjusted for differences in patient age, severity of illness, secondary diagnoses and admission status, significant mortality rate differences persisted: 9% versus 4% for low and high volume surgeons, respectively (p less than 0.001), and 12% versus 5% for low and high volume hospitals, respectively (p less than 0.001). Surgeons who performed more than 7 aneurysm operations per year devoted more of their practice to aortic (11%) and vascular operations (52%) than did surgeons who performed 7 or fewer aneurysm operations per year (2% and 19%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Prospective randomized multicenter comparison of in situ and reversed vein infrapopliteal bypasses

We have performed a prospective, randomized, multicenter study to compare in situ and reversed vein grafts for long limb salvage bypasses from the proximal thigh to an infrapopliteal artery. Three hundred eighty-four patients required an infrapopliteal bypass for critical lower extremity ischemia. Of these, 259 were excluded because a short vein bypass was performed or because the vein was considered inadequate. The remaining 125 patients had a randomized vein bypass, 63 reversed, 62 in situ. The two groups were similar with regard to risk factors, indications, graft dimensions, and outflow. Secondary patency at 30 months was similar for both techniques: reversed 67% +/- 9% (+/- SE); in situ 69% +/- 8%. For veins less than or equal to 3.0 mm in minimum distended diameter 24-month patency rates were 61% +/- 22% for 12 in situ veins and 37% +/- 29% for 10 reversed veins (p greater than 0.05). Angiographic evaluation of failing grafts revealed lesions similar in type and frequency in both types of grafts. These included focal (in situ, n = 4; reversed, n = 7) and diffuse vein hyperplasia (in situ, n = 2; reversed, n = 1), and inflow and outflow stenoses (in situ, n = 4; reversed, n = 3). The incidence of wound complications and the mortality rate were similar for the two groups. These data show no significant difference in overall patency rates for the two types of vein grafts at 2 1/2 years.(ABSTRACT TRUNCATED AT 250 WORDS)

The IARC classification system: input, internal logic, output, and impact

The IARC Monographs "Evaluation of Carcinogenic Risk of Chemicals to Man" elegantly condense and classify information on carcinogenic hazards. They serve as an invaluable basis for the regulation of carcinogenic exposures, yet the monographs are inadequate in several respects: 1. The monographs reflect only what is reported and published in peer-reviewed sources; they have not themselves generated support for studies on agents and processes for which information is lacking, partial, or inadequate. 2. There has been misuse of the output, which reflects varying levels of certainty as to human health hazards. Lack of absolute certainty on human carcinogenicity has been used as a basis for deferring regulations or other preventive action to restrict exposures. 3. The monographs ignore high-risk situations which may result from combined or interactive effects, because of the orientation mostly on specific agents. There is not adequate attention to frequently reported excesses of disease other than cancer in certain occupations with mixed exposures. Earlier recognition of more widespread and more reversible effects, other than cancer, needs to be emphasized to control exposures. 4. Control of carcinogenic exposures for workers has been less exacting and consistent than control of exposures for the community at large (water, air, food, and drugs). 5. The gap between knowledge of risks and action to control them is great and calls attention to the need for more aggressive professional input.

Interruption of critical aortoiliac collateral circulation during nonvascular operations: a cause of acute limb-threatening ischemia

In patients with aortoiliac occlusive disease interruption of critical collaterals during another nonvascular or cardiac operation may threaten limb viability. This occurred in four patients whose limb-threatening ischemia was precipitated by radical cystectomy with bilateral hypogastric artery ligation, left colon resection, or coronary artery revascularizations by means of the internal mammary artery. Important collateral pathways, the interruption of which may account for this phenomenon, are detailed, and approaches are outlined for prevention and management of acute ischemia in this setting.