Serial imaging of canine myocardial infarction by in vivo nuclear magnetic resonance.

Anterior infarction was produced in eight dogs to characterize serial changes in nuclear magnetic resonance signal intensity within the infarct zone. Magnetic resonance imaging was done on the day of infarction, on day 4, 5 or 6, on day 13 and day 20 using a 0.15 tesla (6.25 MHz) resistive imager. Electrocardiographically triggered spin echo (30, 45 and 60 ms echo times) and inversion recovery (400 to 500 ms inversion time) pulse sequences were employed to obtain single slice images. On day 20, the excised hearts were sectioned and examined to determine infarct location and extent. In the spin echo images, signal intensity within the ischemic zone was visibly increased in seven of the eight dogs on the day of infarction, and in all dogs by days 4 to 6. Signal intensity remained elevated in all but two dogs at day 20. With inversion recovery imaging, changes in the infarct zone were highly variable; both ill defined increases and decreases in signal intensity were noted. With a 30 ms echo time, signal intensity in the infarct zone was increased on average 29.8 +/- 24.1% above that in normal myocardium on the day of infarction. The relative signal intensity increased to 62.4 +/- 23.5% during the first 2 weeks after infarction (p less than 0.05), then decreased to 12.0 +/- 18.5% by day 20 (p less than 0.05). Similar changes were detected in the images using the 45 and 60 ms echo times. Nuclear magnetic resonance imaging therefore is able to detect regions of myocardial infarction and follow evolutionary changes in signal intensity within the infarct zone with healing.

Blind esophagectomy for extrinsic carcinoma of larynx.

Esophagectomy without thoracotomy has several advantages in those patients requiring laryngectomy and in whom the stomach is used for replacement. A two-team approach is advocated. The posterior mediastinal route is preferred.

Confirmation of infection of an aortic graft.

The presentation of an aortic graft infection may be dramatic in the form of an aortoenteric fistula or drainage of pus from the wound. Some cases may be more subtle with presentations of fever of unknown origin. Prior to embarking upon major operative repair for these suspected lesions, it is essential to confirm the presence of infection. Under CT control, a fine needle may be inserted into the peri-graft space, and cultures may be obtained. Further confirmation may be achieved by an injection of a small amount of contrast material which will demonstrate lack of incorporation of the graft into surrounding tissues. Prior confirmation of graft infection permits a staged procedure to repair this technique is illustrated with a case history.

Rehabilitation potential of elderly patients with major amputations.

This study was undertaken to determine the rehabilitation potential of patients undergoing amputation for vascular disease. A total of 101 patients were studied with a mean age of 69 +/- 14 years, 26 of whom were over age 80. Operative indications were gangrene or ulceration in 80% with rest pain in 20%. Eighteen patients were bilateral amputees. Fifty per cent of the patient population had previous vascular operations. The operative mortality was 13% and was not affected by the age of the patients or the presence of diabetes. Most operative deaths were due to cardiac or septic respiratory complications. Twenty-four of 88 surviving patients were not considered candidates for rehabilitation and the major determining factor was the occurrence of a remote or perioperative stroke. None of these 24 patients was discharged from institutional care. Sixty-four patients were considered rehabilitation candidates with equal distribution in all age groups. Ninety-five per cent of these patients were discharged home with 80% of those patients over 80 being discharged. Eighty-seven per cent of the elderly rehabilitation candidates were fitted with prostheses which compares favourably to other age groups. Seventy-three per cent of the elderly reached their rehabilitation goals (most frequently ambulation with the aid of a walker) which is only slightly less than the younger amputation group. From this study we conclude that amputations which are done for ease of nursing care and patient comfort in debilitated patients have a high mortality rate and rehabilitation goals are unlikely to be met. We have demonstrated high success rates with rehabilitation including patients over age 80. The majority of these patients may be discharged home after a period of aggressive rehabilitation.

Intraoperative thrombolytic therapy as a treatment of small vessel thrombosis: an experimental study.

OBJECTIVE: This paper studies the effect of three doses of Streptokinase infused intra-operatively into an animal model of small vessel thrombosis. EXPERIMENTAL DESIGN: This is a controlled trial of intraoperative infusion of thrombolytic agent into a thrombosed arterial segment compared to no infusion into the contralateral limb. EXPERIMENTAL SUBJECTS: 19 New Zealand White rabbits were stratified into 3 groups. INTERVENTIONS: Thrombosis was achieved by infusing a mixture of topical thrombin and autologous blood into individual iliac arteries of the New Zealand white rabbit. A randomly selected hind limb had an infusion of one of three doses of streptokinase (A = 2,500u; B = 5,000u; C = 10,000u) in saline over 20 minute period. Preinfusion and post infusion angiography was performed. MEASUREMENTS: Angiograms were ranked by a radiologist blinded to the side of infusion and clotting parameters were assessed. RESULTS: All limbs at all doses of streptokinase infusion (SK) showed significant clot lysis when compared to the non-infused limb(C). The percentage of improved segments is as follows: iliac: SK = 100%, C = 79%; femoral SK = 79%, C = 32%; tibial SK = 52%, C = 5%. Although there was an elevation in clotting time and a reduction in fibrinogen, levels remained within normal limits. CONCLUSIONS: Streptokinase infused directly into thrombus in arteries even in low doses significantly enhances thrombolysis of vessels which are too small to be cleared by mechanical means. No significant systemic complications were encountered.

A simplified method of performing patch angioplasty for profunda femoris origin stenosis.

A simplified method of performing an autogenous profundoplasty is described using the partially detached and open superficial femoral artery as a patch. This permits better visibility while performing the anastomosis since the superficial femoral artery is no longer obstructing the view, which also allows easy access to any bleeding following clamp removal.

Oral acetylsalicylic acid improves patency rates in small-vessel anastomoses.

Because platelet aggregation is the critical step in vascular thrombosis, this study investigated the possibility that acetylsalicylic acid given orally would improve patency of anastomoses in small arteries. Under clean conditions, in male Sprague-Dawley rats, the superficial femoral arteries were divided and reanastomosed using the sleeve technique with 10-0 nylon suture. Fifty-one rats received a full laboratory diet and acetylsalicylic acid in their drinking water (1.08 mg/ml), before and after operation. A control group of 54 rats was matched for weight, water intake and duration of vessel occlusion. Vessel patency was assessed on postoperative day 7, at sacrifice, by dye angiography. In the experimental group 7 (13.7%) anastomoses became occluded, compared with 20 (37.0%) in the control group (chi 2 = 5.99, df = 1, p less than 0.025). Serum thromboxane B2 levels in five rats given acetylsalicylic acid orally (33.1 +/- 6.1 ng/ml) were significantly (p less than 0.001) lower than in five control rats (86.6 +/- 49.1 ng/ml). The authors concluded that acetylsalicylic acid administered in the drinking water to Sprague-Dawley rats improved the patency rate of femoral artery anastomoses probably because of a reduction in platelet aggregation. Orally administered acetylsalicylic acid may be of clinical benefit to patients who undergo small-vessel anastomoses.

Neurologic complications and lumbar laminectomy. A standardized approach to the multiply-operated lumbar spine.

Even the careful and knowledgeable spine surgeon will encounter a variety of neurologic complications during and after routine lumbar laminectomy. These include dural and nerve root injuries; cauda equina syndrome; and formation of scar tissue, extradural and intradural (arachnoiditis). The surgeon must be prepared to identify each of these problems and deal with them effectively at the time of the procedure and in the immediate postoperative and follow-up periods. The physician evaluating the multiply-operated lumbar spine patient must use an organized approach. The origin of the problem in most instances is a faulty decision to perform the original operative procedure. Further surgery on an "exploratory" basis is not warranted in any situation and most likely will lead only to further disability. There should be definite objective findings to substantiate the patient's symptoms. The etiology of each patient's symptoms. must be accurately localized and identified. Medical status and psychosocial situation--as well as orthopedic and neurologic findings--should be evaluated at the time of the initial consultation. Once the spine is identified as the probable source of symptoms, specific features should be sought in the patient's clinical history, physical examination, and roentgenographic studies. The number of previous operations, length of pain-free interval, and predominance of leg versus back pain are the major historic signposts. The presence of a tension sign and the neurologic findings are the focal points of the physical examination. Plain roentgenograms, motion films, water-soluble myelogram, computed axial tomography, and magnetic resonance imaging with contrast have specific roles in the workup.(ABSTRACT TRUNCATED AT 250 WORDS)

Traumatic rupture of the right hemidiaphragm.

Six cases of traumatic rupture of the right hemidiaphragm are reviewed with emphasis on diagnostic features and operative treatment. In one (Case 6), a mass lesion was seen in the chest 2 years after the initial injury and was repaired through a right thoractomy incision. There were no deaths. Of the five cases operated on soon after the initial injury, two were approached initially via right thoracotomy incisions and both required second incisions for injuries below the diaphragm. Three ruptures of the right hemidiaphragm were successfully repaired through laparotomy incisions without extension of the incision into the chest. Laparotomy is the preferred approach for rupture of the right hemidiaphragm during the acute phase, because exposure is adequate and life-threatening injuries below the diaphragm can usually be dealt with through the same incision.

Mediastinal lymph-node biopsy is a definitive staging procedure for bronchogenic carcinoma.

Mediastinal lymph-node biopsy has been performed as a staging procedure in most cases of bronchogenic carcinoma since 1965. This study was carried out to assess the results of staging by this method in 75 patients. Biopsy sites were marked with hemoclips. Three zones were defined: zone 3 (inoperable), beyond the midline and above the lower border of the aortic arch; zone 1 (operable), more than 3 cm from the carcinoma, ipsilateral to the tumour; and zone 2, between zones 1 and 3. Forty of 75 patients had biopsy specimens showing carcinoma. The proportion was highest in small cell anaplastic carcinoma and lowest in squamous cell tumours. Of the 40 positive biopsies 35 were from zone 3. All the positive biopsy specimens showing small cell anaplastic carcinoma were from zone 3. Positive specimens correlated strongly with other evidence of inoperability. Mediastinal lymph-node biopsy is a definitive staging procedure.

Serial nuclear magnetic resonance imaging of acute myocardial infarction with and without reperfusion.

To compare nuclear magnetic resonance (NMR) image-derived T1 and T2 changes during evolving infarction, 14 dogs were studied serially: (1) 1 to 2 hours after left anterior descending coronary occlusion, (2) 2 to 3 hours after coronary occlusion (n = 7) or in the first hour after reperfusion following 2 hours of occlusion (n = 7), and (3) 5 days and (4) 21 days after occlusion/reperfusion. In addition, the extent of T1 and T2 abnormalities was compared to the extent of infarction as determined histologically for each set of images. With sustained coronary occlusion, an increase versus control values (T1 = 351 +/- 11 msec; T2 = 41 +/- 2 msec) was observed in the second hour after occlusion (T1 = 448 +/- 51 msec; T2 = 51 +/- 8 msec), gradually reaching a maximum by day 5 (T1 = 490 +/- 64 msec; T2 = 63 +/- 9 msec). By 21 days, T1 had decreased to 427 +/- 43 msec and T2 to 55 +/- 11 msec. However, with myocardial reperfusion, an abrupt increase in both T1 and T2 occurred compared to prereperfusion values in the first hour after release of occlusion, from 445 +/- 32 msec to 555 +/- 65 msec and from 52 +/- 5 msec to 65 +/- 8 msec, respectively. Subsequently, T1 remained elevated whereas T2 normalized. Only on day 21 images was there a good correlation between the extent of T1 and T2 abnormalities and infarct size, in both nonreperfused (r = 0.87; p less than 0.05), and reperfused (r = 0.89; p less than 0.01) dogs.(ABSTRACT TRUNCATED AT 250 WORDS)

Simple method of intraoperative blood collection and reinfusion during aortic surgery.

The increasing fear of acquired immune deficiency syndrome and other blood-transmissible diseases and increasing blood-bank shortages prompted a study of the safety and feasibility of a commercially available hand-held unit for collecting and reinfusing blood. The device was used on nine patients undergoing aortic surgery and permitted a mean saving of 2.6 units of banked blood. The reinfusion of collected blood did not result in any coagulation disturbances or changes in renal function. The hemoglobin and platelet levels were comparable to those in a group of patients receiving only banked blood. The unit does not require additional personnel or technical training for its use. The authors conclude that this autotransfusion device is a safe and feasible method of reducing the requirement for banked blood during aortic surgery.

Early detection of canine myocardial infarction by magnetic resonance imaging in vivo.

This study was undertaken to assess the ability of proton magnetic resonance imaging (MRI) to detect myocardial ischemia shortly after coronary artery occlusion. Fifteen dogs were studied before and serially for up to 6 hr after anterior descending or circumflex coronary artery ligation in vivo by gated MRI with a 0.15 tesla resistive magnet (resonant frequency of hydrogen 6.25 MHz). Image acquisition was by single-spin echo, with echo times (TE) of 30 msec and TE 60 msec, and modified inversion recovery pulse sequences. Excellent anatomic definition was observed. By 4 hr after coronary artery occlusion the signal in the infarct zone increased to 36 +/- 20% greater than that in the adjacent normal myocardium for the TE 30 msec sequence (p less than .01) and to 116 +/- 100% for the TE 60 msec sequence (p less than .05). The most intense increase in signal was noted with the TE 60 msec pulse sequence and because normal myocardium is not well visualized by this technique, acutely ischemic myocardium was clearly delineated. Inversion recovery imaging did not show areas of ischemia. Changes seen on MR images correlated well with the location of ischemic changes noted on microscopic examination of the excised hearts. MRI thus provides a noninvasive means for detection of ischemia early in the course of myocardial infarction.

The application of 67Ga scanning in determining the operability of bronchogenic carcinoma.

In a prospective study of 34 patients with histologically proven bronchogenic carcinoma, 67Ga scanning of the chest was used to screen for mediastinal involvement. Mediastinal scans and pathologic findings were in agreement in 27 patients. Two patients had false-negative scans and 5 had positive scans but no evidence of mediastinal tumor. These results indicate a sensitivity of 89%, a specificity of 66.6%, an accuracy of 77% for positive scans, and an accuracy of 83% for negative scans. Overall correlation between 67Ga scanning of the chest and mediastinal-tumor involvement is statistically significant (P = 0.003).

Quantification of myocardial blood flow and extracellular volumes using a bolus injection of Gd-DTPA: kinetic modeling in canine ischemic disease.

In order to clarify the relationship between coronary artery disease (including myocardial infarction) and image contrast in gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA)-enhanced MRI it was decided to model the myocardial tissue distribution and clearance of Gd-DTPA using the modified Kety equation. Using a canine model, myocardial tissue Gd-DTPA concentrations ([Gd-DTPA]m) were measured 1 or 5 min after a bolus injection of Gd-DTPA or immediately after the end of a constant infusion of Gd-DTPA in a total of 35 dogs. It was found that within 5 min of a bolus injection [Gd-DTPA]m is determined primarily by myocardial blood flow (MBF) and after about 10 min primarily by myocardial extracellular volumes (MECV). This study suggests that repeat, rapid (every 2-4 s) measurements of myocardial T1 relaxation rates following the bolus injection of Gd-DTPA are required to calculate MBF (i.e., myocardial tissue perfusion) and MECV.

Extra-anatomic bypass grafting: a rational approach.

To determine predictors of long-term patency in extra-anatomic bypass grafting, the authors studied retrospectively the charts of 134 patients who underwent bypass grafting (axillofemoral in 17, axillobifemoral in 32 and femorofemoral in 85). Of the study group, 64% were men; the mean age was 65 +/- 12 years (+/- SEM). The indications for grafting were limb salvage (102), claudication (27) and replacement of septic grafts (5), and for using the extra-anatomic route included high risk (83), sepsis (8) and unilateral disease (34). Operative mortality was 6% and the early graft occlusion rate 7.4%. The late death rate was 44%. At 3 years, the life-table patency rates for the various procedures were axillofemoral 52.5%, axillobifemoral 67.7% and crossfemoral 86.9%. Smoking significantly (p less than 0.05) decreased the patency rate, but diabetes did not. However, amputation was more frequent in diabetics. Indications for operation did not alter patency rates, but did affect operative mortality. The authors conclude that extra-anatomic bypass grafting is highly successful, but not as successful as anatomic bypass. When appropriate, the axillobifemoral graft is preferred to the axillounifemoral graft because of its increased patency. Crossfemoral grafts must be carefully monitored to ensure that no donor limb stenosis occurs and this procedure should not be attempted unless the disease is truly unilateral.