Monitoring of midmyocardial and subendocardial pH in normal and ischemic ventricles.

Midmyocardial and subendocardial pH monitoring was used as an indirect method for continuous evaluation of regional canine myocardial ischemia. Left ventricular midmyocardial pH (pHm) at 4 mm. depth was monitored in 10 dogs, under resting conditions, by means of a 5 mm. Beckman pH probe. pHm was 6.96 +/- 0.03, recorded at myocardial temperatures of 35 to 37 degrees C. Ischemia was then produced by snare occlusion of the proximal left main coronary artery for 2 minutes. pHm decreased to 6.87 +/- 0.03 (p less than 0.01) at 1 minute and 6.80 +/- 0.04 (p less than 0.005) in 2 minutes. When flow was restored, pHm returned toward normal within 2 minutes (pH 6.86 +/- 0.03) and at 5 minutes had returned to control values (pH 6.93 +/- 0.03). In another 5 dogs under similar conditions, pHm at 4 mm. and subendocardial pH (pHe at 8 mm.) were measured. Baseline pHm (6.97 +/- 0.01) and pHe (6.84 +/- 0.02) levels were significantly different (p less than 0.0005). After 2 minutes of ischemia, pHm was 6.82 +/- 0.03, whereas pHe decreased to 6.78 +/- 0.04 (p less than 0.1). Five minutes after snare release, pHe remained at 6.73 +/- 0.07; pHm (6.93 +/- 0.03) returned to control values. Both pHm (6.93 +/- 0.02) and pHe (6.84 +/- 0.09) levels were normal 15 minutes after release of the snare. The midmyocardium and subendocardium have different pH levels which can be monitored. Ischemia produces different pH patterns in these layers. pHm returns to control values within 5 minutes after 2 minutes of ischemia, whereas pHe remains depressed for at least 5 minutes. pH monitoring provides an accurate and simple method for on-line evaluation of endocardial ischemia.

The Lillehei-Kaster aortic valve prosthesis. Long-term results in 273 patients with 1253 patient-years of follow-up.

The Lillehei-Kaster aortic valve prosthesis was inserted in 313 patients between August 1975 and December 1984. Aortic valve replacement alone was done in 193 patients. Additional procedures included coronary artery bypass grafting in 62 patients, mitral valve replacement in 22, mitral valvuloplasty in 8, and miscellaneous procedures in 28. The 273 patients discharged from the hospital are the basis of this report. They have been followed up for 1253 patient-years. The range of follow-up is 1 to 11 years, and the mean is 4.6 years. The 5-year survival rate for all patients was 68%, whereas for aortic valve replacement alone it was 76%. The incidences of embolism, thrombosis, bleeding, periprosthetic leak, valve infection, and reoperation per 100 patient-years were 1.5, 0.2, 2.0, 0.8, 0.7, and 1.3, respectively. The 5-year rates of freedom from embolism, thrombosis, bleeding, periprosthetic leak, valve infection, reoperation, and any valve-related complication were 94%, 99%, 91%, 96%, 97%, 94%, and 76%, respectively. Four of 16 patients who required reoperation had a properly functioning valve whose effective orifice area was too small for the cardiac output. Each of these valves was of the smaller size. There were no instances of mechanical valve failure. The Lillehei-Kaster aortic valve prosthesis is an excellent aortic valve substitute in the larger sizes. It has an extraordinary record for mechanical durability and an excellent resistance to thromboembolism in patients receiving proper anticoagulation. The incidence of perivalvular leak and infection is similar to that of other prosthetic valves. However, it is not to be recommended in the smaller sizes because of an unfavorable ratio of effective orifice area to tissue diameter.

Delayed appearance of left-to-right shunt following aortic valvular replacement. Report of two cases.

Two cases are presented in which a left-to-right shunt occurred late following aortic valvular replacement. In one patient a fistula was found between the aortic root and the right atrium and ventricle. In the second patient a defect developed in the membranous septum, allowing shunting from the left ventricle to both the right atrium and right ventricle.

Vascular surgery--is it different?

In 1972 the Society for Vascular Surgery and the North American Chapter of the International Cardiovascular Society recommended that the American Board of Surgery establish a method for the certification of special competence in vascular surgery. The American Board of Surgery in 1974 judged that, for the present, vascular surgery training best could be upgraded by certifying training programs and not individuals. The Residency Review Committee for Surgery now has approved guidelines which define acceptable vascular surgery training programs. These guidelines require approval of the American Medical Association and the governing bodies of the Liaison Committee for Graduate Medical Education before accreditation procedures can be implemented. It is proposed that vascular surgery is different enough from general surgery and cardiothoracic surgery so that special training programs are needed. Vascular surgeons require a fund of knowledge and surgical skills beyond that learned in most surgical programs as well as a special experience with vascular operations if they are to provide optimal patient care. Acceptance of the principle of the accreditation of surgeons caring for vascular surgical problems is an important step in the upgrading of vascular surgery.

Autogenous venous grafts ten years later.

The status of 103 patients and their 113 autogenous venous femoropopliteal bypass grafts exactly 5 years after operation was presented previously. A 10 year follow-up now is possible. The mortality rate at 5 years was 48% (50 of 103) and at 10 years was 73% (75 of 103). Myocardial infarction was considered to be the cause of death of 36% of the 103 patients. The actual graft patency rate for survivors at 5 years was 59% (35 of 59) and at 10 years was 38% (11 of 29). Utilizing the same date, late graft patency rates of 45%, 58%, and 58% would have been calculated or predicted by other methods of reporting. Of 46 extremities operated on for claudication, 22 patients were alive and 45% of grafts (10 of 22) were patent 10 years later. Of patients with a total of 67 extremities operated on for rest pain or gangrene, only seven patients were alive and 14% (one of seven) of the grafts patent. Patency rates at 10 years of short grafts were 43% (nine of 21) and of long grafts 25% (two of eight). Extremities with good runoff had patency rates of 41% (nine of 22) at 10 years and those with poor runoff had patency rates of 29% (two of seven). Arteriograms demonstrated atherosclerotic changes in one of 18 grafts at 5 years and in two of eight grafts at 10 years. This study provides more facts for answering the questions of patients regarding long-term prognosis following their arterial reconstruction. It is important to analyze carefully any report in which a comparison of patency rates is suggested or invited.

Revision of failed infrainguinal bypass graft: principles of management.

Our experience with 112 patients whose infrainguinal bypass grafts (IIBPGs) failed more than 30 days after insertion was reviewed. Cumulative patency rates (CPRs) after graft revision (GR) were 71% at 6 months, 62% at 12 months, 57% at 24 months, 54% at 36 months, and 46% at 48 months. CPRs of IIBPGs that failed more than 12 months after insertion were higher than those of grafts that failed earlier (60% vs. 36% at 36 months (p less than 0.05). Failure of the initial GR did not preclude a successful secondary revision. The 3-year CPR of the initial GR was 31% compared with 49% for secondary GR (p = no significance). The results of GR are significantly better when graft failure is diagnosed before graft thrombosis. Revision of the 37 hemodynamically failed but patent grafts resulted in a CPR of 89% at 12 months and 77% at 36 months compared with a CPR of 33% at 12 months and 26% at 36 months after revision of the 75 thrombosed grafts (p less than 0.01). Hemodynamically failed but patent grafts occurred in 36 of 68 patients (53%) with failed autogenous veins but only 1 of 44 patients (2%) with a failed prosthetic graft had GR before thrombosis of the graft. There is a significant improvement in early CPR when a new bypass graft is inserted as compared with original graft thrombectomy and angioplasty. The CPR for new bypass grafts at 6 and 12 months was 61% and 41%, respectively, compared with a CPR of 26% and 20% for the same time intervals with graft thrombectomy and angioplasty (p less than 0.05). The presence of thrombus in the outflow artery at the site of GR is a contraindication to anastomosis at that site even if arterial thrombectomy reestablishes backflow. When distal arterial thrombus was not present, the CPR after GR was 62% at 6 months, 42% at 12 months, and 33% at 36 months. When distal arterial thrombectomy was necessary, the CPR after GR was only 14% at 6 months and zero at 12 months (p less than 0.05).

Natural history of recurrent and residual stenosis after carotid endarterectomy: implications for postoperative surveillance and surgical management.

BACKGROUND: Noninvasive surveillance of patients after carotid endarterectomy is practiced routinely to detect recurrent stenoses. Many authors advocate repair of asymptomatic severe stenoses so detected. The likelihood of these lesions causing neurologic symptoms is unknown. Our aims were to (1) define the incidence of lesions, (2) determine the frequency of associated neurologic symptoms, and (3) identify patient-dependent factors that might predict restenosis. METHODS: Data on the status of 449 carotid arteries after endarterectomy were reviewed. The number of recurrent and residual severe (greater than or equal to 80%) stenoses was identified. Interval to development of symptoms was determined by life-table analysis. Patient-dependent factors (age, gender, smoking, diabetes, and patch closure) were evaluated by univariate and multivariate analysis to identify possible associations with severe lesions. RESULTS: Severe (greater than or equal to 80%) stenoses were seen in 35 patients (7.9%). Residual lesions were seen in 17 cases (eight occlusions and nine stenoses); recurrent lesions were identified in 18 patients (3.9%). Symptoms developed in five cases (14%) (one residual and four recurrent) 35, 48, 68, 98, and 103 months after surgery. The likelihood of developing symptoms associated with stenosis at 5 years was 6%. No factors correlated with residual stenosis. Age less than 60 years, female gender, primary closure, and absence of diabetes were more common in patients with recurrent lesions. CONCLUSIONS: Severe lesions can be found after carotid endarterectomy in at least 8% of patients and consist of residual defects, as well as recurrent stenoses. Recurrent lesions are more common in specific patient subgroups. These lesions are stable for long periods and the majority remain asymptomatic. Operation is not indicated unless symptoms develop in these patients. Intraoperative completion evaluation may be indicated to reduce the incidence of residual disease. Early noninvasive evaluation is useful as a quality-control measure. Repeated surveillance may provide data on the course of restenosis or contralateral disease progression but is of limited clinical benefit.

Platelet aggregation inhibition in human umbilical vein grafts and negatively charged bovine heterografts.

Glutaraldehye-tanned human umbilical vein grafts (4 mm) and negatively charged bovine heterografts (4 mm) were placed as bypasses in the femoral arteries of 20 dogs randomized into 10 treated with aspirin and dipyridamole and 10 were not treated. Autogenous vein grafts were placed as controls. Platelet aggregation inhibition by aspirin and dipyridamole significantly improved the patency of human umbilical vein grafts from 10% to 60%. It had no effect on patencies of autogenous veins (100%) or on negatively charged bovine heterografts (0% patency). Inherent graft properties continue to play an important and sometimes overriding role in long-term graft patency in small vessel bypasses. Neointimal fibrous hyperplasia at both proximal and distal anastomoses again was shown to be intimately associated with late graft occlusions.

Arterial embolectomy before and after the Fogarty catheter.

Arterial emboli were extracted from 79 patients between 1955 and 1963 with polyethylene catheter suction systems and/or retrograde flushing and from 149 patients between 1963 and 1973 with Fogarty catheters. The Fogarty-era patients were older, had a greater incidence of ischemic heart disease, and presented with a greater degree of preoperative peripheral ischemia. The limb salvage rate of 87 percent after Fogarty catheter embolectomy was not statistically different from the salvage rate of 79 percent after suction catheter embolectomy, but the number of limbs with distal pulses postoperatively was significantly greater after Fogarty treatment, 64 vs. 42 percent. Delay in treatment and the presence of prior occlusive vascular disease adversely affected results in both eras. The in-hospital embolic recurrences occurred in 9 percent of the patients anticoagulated postoperatively and in 31 percent of those not anticoagulated. Heparin and warfarin were equally effective in preventing recurrences, but wound complications were seen in 33 percent of the heparinized patients, compared with 7 percent of those receiving warfarin and 4 percent of those not anticoagulated.

Effects of aspirin and dipyridamole on expanded polytetrafluoroethylene graft patency.

A randomized, double-blind clinical trial was designed to assess the effect of aspirin (ASA) alone or in combination with dipyridamole (DIP) on the patency rates of expanded PTFE grafts placed in the infrainguinal position. Forty-nine patients were randomized into three groups who received three times daily either two placebos (17 patients), 325 mg ASA and placebo (16 patients), or 325 mg ASA and 75 mg DIP (16 patients). The patients were seen at 3-month intervals for 1 year, and coded medication bottles were dispensed and returned pills counted to assess patient compliance. Treatment failure was defined as the first graft occlusion. The data were analyzed using the Breslow statistic for progressively censored survival type data. The 1-year cumulative patency rate for the entire series was 59%. The rates for above-knee grafts in the ASA group (100%) and the ASA/DIP group (100%) were significantly higher than the rates for the placebo group (50%) (P = 0.05). The 1-year cumulative patency rates for patients with below-knee grafts were not statistically different among the groups, although the patients who received ASA alone had a higher rate than did the other two groups (65% versus 21% for placebo and 19% for ASA/DIP). There were fewer occlusions in the above-knee grafts as compared to below-knee grafts in all groups, but the differences were statistically significant only in the ASA/DIP group. There were no statistical differences between the two active treatment groups.

Economic implications of thrombolysis or operation as the initial treatment modality in acute peripheral arterial occlusion.

BACKGROUND: Thrombolytic agents have been used to treat arterial occlusion for almost 40 years. Recently, an investigation of the costs associated with two treatment options for acute peripheral arterial occlusions, thrombolysis and surgical intervention, was completed. The availability of hospital cost data for patients enrolled in the thrombolytic and operative treatment groups provided a basis with which to accurately assess the financial impact of the different treatment strategies, both from a purely financial standpoint and in relation to outcome. METHODS: The patient base was composed of 114 patients with acute limb ischemia of less than 7 days' duration. The patients were randomly assigned to receive urokinase (n = 57) or to undergo an operation (n = 57) as the initial therapeutic intervention. Patients in the thrombolytic group underwent standard intraarterial diagnostic arteriography, and patients with embolic events, in whom complete lysis of all embolic and propagated thrombotic material was achieved, were subsequently treated with heparin and long-term warfarin (Coumadin) therapy. The economic analysis was undertaken after the completion of the trial. Statistical comparisons between groups were made with the Student t test for continuous, normally distributed data. Mortality and limb salvage rates were calculated from Kaplan-Meier curves, appropriate for the censored nature of the data. RESULTS: The total treatment costs did not differ significantly between the two treatment groups ($22,171 +/- $4,959 in the thrombolytic group and $19,775 +/- $5,253 in the operative group). The total hospital charges were similar between the two groups. Overall, the total charges were remarkably similar between the two treatment groups, averaging $40,823 +/- $8,764 in the thrombolytic group and $41,930 +/- $10,398 in the operative group. CONCLUSIONS: An economic analysis of the data confirmed that the total economic impact of thrombolysis approximated that of initial operative therapy. The improved clinical outcome in patients treated with thrombolysis suggests that this modality may be appropriate as the initial therapeutic intervention in the select group of patients seen within the first few hours of an acute peripheral arterial occlusive event.

Angiographic and pathologic correlates in carotid artery disease.

Eighty-four consecutive intact atheromata from the carotid bifurcation were examined macroscopically and by standard microscopic techniques. Preoperative angiograms of these cases were reviewed by a single radiologist with special attention to detecting the presence of ulceration. Pathologic and angiographic findings were compared and correlated with the patient's clinical presentation. Macroscopic findings of ulceration were present in 43 cases (51%). Thirty-four specimens contained intramural hemorrhage and 27 showed evidence of mural thrombus. Mural thrombus was significantly associated with evidence of ulceration (p less than 0.01). Intramural hemorrhage was commonly associated with ulceration (25/34) but was also seen in nonulcerated plaques (p greater than 0.05). Angiographic diagnosis of ulceration was made in 54 cases (64%). While angiography identified 78% of macroscopic ulcers (34/43; p = 0.05), seven typical ulcerations were missed angiographically and there were 18 angiographic false positive results (18/54:33%). Macroscopic ulcerations were most common in patients with symptoms of hemispheric ischemia (p less than 0.1). The angiographic diagnosis of ulceration did not correlate with the patient's clinical presentation (i.e., hemispheric ischemia, nonhemispheric ischemia, or asymptomatic stenosis). These results support the thesis that macroscopic ulceration is an important cause of hemispheric ischemia. Angiography does not reliably predict the presence of macroscopic ulceration and this limitation should be kept in mind when patients with hemispheric symptoms are evaluated. Such patients should not be denied consideration for endarterectomy simply because the angiogram fails to demonstrate ulceration.

Asymptomatic contralateral carotid artery stenosis: a five-year follow-up study following carotid endarterectomy.

Exactly 5 years after carotid endarterectomy for transient ischemic attacks (TIAs), the neurologic status of each of 67 patients whose angiograms demonstrated a contralateral carotid artery, two of which were fatal. One of these patients suffered antecedent TIAs. Two of the 50 patients (4%) without contralateral carotid stenosis experienced symptoms referable to the contralateral carotid; one of the 50 (2%) suffered a CVA without antecedent TIAs; and one of the 50 (2%) experienced a single TIA. Patients with a demonstrable contralateral carotid stenosis were at greater risk of developing contralateral symptoms than those without a stenosis [14 of the 67 versus two of the 50 (P < 0.01)]. There was no correlation between the incidence of new symptoms and the degree of contralateral stenosis. The 3% (two of the 67) incidence of stroke without antecedent TIAs on follow-up in those patients with a contralateral carotid stenosis suggests the following guideline: patients with contralateral carotid stenosis suggests the following guideline: patients with contralateral carotid artery stenosis can be advised to undergo staged carotid endarterectomies if the surgeon's stroke and morbidity rate is less than 3%.

The occluded renal artery.

Twenty-seven cases of renal artery occlusion are presented. In 16 patients the duration of occlusion could be determined and only two of 16 became hypertensive or experienced worsening of existing hypertension. Seven of 11 patients in whom the duration was unknown were hypertensive. Twelve patients were not treated and of these, ten are deceased with renal artery occlusion contributory in six deaths. Nine patients underwent nephrectomy and of eight hypertensive patients, five became normotensive. Six underwent revascularization and four were successful at 2 hours, 22 hours, 9 days, and 39 days, respectively, after occlusion. The experience leads us to conclude that viability can be proven only by direct observation and that revascularization with return of function and lowering of blood pressure is possible after prolonged periods of occlusion.

Effect of prostaglandin E1 on blood flow in normal and ischemic canine hindlimbs.

Prostaglandin E1 (PGE1) is a potent vasodilator that will increase peripheral blood flow. After infusion of PGE1, little is known about the distribution of flow between skin and muscle or the effect of PGE1 on an ischemic leg. We infused intra-arterially PGE1 (5 ng/kg/min) into normal and ischemic canine hindlimbs. Radioactive microspheres were used to measure nutrient flow to skin and muscle and flow shunted through arteriovenous connections. Intra-arterial PGE1 caused significant increases in skin blood flow in both normal and ischemic hindlimbs. Shunted flow did not increase. Muscle flow increased in normal canine hindlimbs, but this increase was prevented by femoral artery ligation. We conclude that PGE1 increases absolute nutrient flow rather than opening arteriovenous shunts in the canine hindlimb. Skin flow is most sensitive to prostaglandin infusion. Muscle flow is increased in normal but not ischemic limbs. PGE1 may be useful in situations where vasospasm is a prominent feature. The role of PGE1 in atherosclerotic ischemic disease remains unclear.

Fibromuscular dysplasia of the internal carotid artery: its occurrence with acute stroke and its surgical reversal.

A case of fibromuscular dysplasia (FMD) of the internal carotid artery that caused acute stroke was successfully treated, with total removal of the FMD rings along with their attached thrombus without segmental excision of the artery. The natural history of this disease is unknown, which raises a concern in management of the many patients with FMD who are asymptomatic. Transient ischemic attack and repeated strokes may be attributable to embolic phenomenon of the thrombus or to platelet aggregates from the FMD segment of the artery. The FMD syndrome can appear as an acute stroke in the young age group. Symptomatic lesions have been managed by excision and arterial reconstruction, by patch angioplasty, or by dilation alone. To our knowledge, this is the first report of total removal of FMD rings without segmental excision of the artery.

Traumatic rupture of the thoracic aorta.

Fifteen patients with blunt traumatic rupture of the aorta, secondary to automobile accidents, that occurred less than seven days prior to admission were treated between 1967 and 1976. The diagnosis was suspected on the basis of roentgenographic evidence of upper mediastinal widening. Aortography demonstrated a localized deformity and dilation of the aorta isthmus just distal to the subclavian artery in all but one patient whose lesion occurred in the mid-descending thoracic aorta. The salvage of one of five patients with free rupture by the prompt institution of total cardiopulmonary bypass has prompted us to begin each operation with the capability of using either left heart bypass or cardiopulmonary bypass. An associated rupture of the right atrium of one patient was successfully controlled. Nine of 12 patients survived the operation, eight were discharged from the hospital, and six were alive and well as least one year later.

Subendocardial protection during cardiopulmonary bypass. Its use with methylprednisolone and glucose-insulin-potassium.

Fifteen adult dogs were equally divided into three groups: group 1 (control) received no medication before or after cardiopulmonary bypass (CPB), group 2 was administered glucose-insulin-potassium (GIK) according to Maroko's protocol before, during, and after CPB, whereas group 3 was treated with methylprednisolone (30 mg/kg) 30 minutes prior to and near the end of CPB. Moderately severe subendocardial hemorrhage was present in 80% of group 1, 50% of group 2, and only 20% of group 3 ventricles. Endocardial viability ratios after CPB were greater than 0.75 in 20% of group 1, 80% of group 2, and 100% of group 3 animals. Both GIK and steroids improved subendocardial perfusion after anoxic arrest and CPB compared with controls. However, steroid-treated dogs exhibited less endocardial hemorrhage, improved contractility, and more rapid return to baseline conditions than either GIK or control animals. These data suggests that steroids could be considered whenever normothermic anoxic cardiac arrest is used for cardiac operations.

A comparison of rapid-healing prosthetic arterial grafts and autogenous veins.

The patency rates and healing characteristics during a nine-month period of internal velour Dacron grafts, external velour Dacron grafts, and Sparks-Mandril grown grafts were compared with autogenous jugular veins when used to bypass short segments of the canine femoral artery. Graft thrombosis occurred in three of 11 external velour grafts, in six of 11 internal velour grafts, and in three of 11 Sparks-Mandril grafts, None of 33 autogenous veins occluded. Graft thrombosis was not correlated with the degree of graft healing but rather with a hyperplastic proliferative intimal lesion observed at the proximal anastomosis of the occluded grafts.

Segmental thrombotic occlusion of infrarenal abdominal aorta.

Five patients had segmental atherosclerotic occlusive disease confined to the midportion of the infrarenal abdominal aorta. Four of five patients had claudication, and in addition, four had evidence of peripheral microembolization and ischemic toes. Local endarterectomy or thrombectomy resulted in satisfactory restoration of distal blood flow in three patients. Two patients required replacement with a prosthetic tube graft. four of five patients have maintained good pedal pulses and have been asymptomatic for up to 14 years. These five cases were compared and contrasted with other series with similar lesions. Several causal factors are involved in segmental aortic occlusions.