Biomedical subjects

J T Christenson

Publications and source records attributed to J T Christenson.

At least 73 records · Page 4Linked to original sources

PubMed1995

Should a mild to moderate ischemic mitral valve regurgitation in patients with poor left ventricular function be repaired or not?

In recent years coronary artery bypass grafting (CABG) has been extended to include patients with very low left ventricular ejection fractions (LVEF), also frequently with co-existing mild to moderate mitral valve regurgitation (MR). The question is, should such a MR be corrected simultaneously with a myocardial revascularization or not? Between January 1989 and November 1994, 56 patients with preoperative LVEF < or = 25% and echocardiographic evidence of co-existing MR (Grade I: 41%, II: 46%, III: 13%) underwent primary CABG. None of them had simultaneous mitral valve surgery. Twenty-nine patients (52%) had a pulmonary artery pressure (PAP) > 40 mmHg. The mean preoperative LVEF was 17.9 +/- 4.6 (10-25), mean PAP 44.2 +/- 16.1 mmHg. An average of 4.5 +/- 1.5 grafts/patient were placed and five patients had simultaneous repair of a post-infarction left ventricular aneurysm. The overall mortality was 3.6% (2/56). Transient post-operative low cardiac output syndrome occurred in 16 patients (29%). Twenty-one patients (38%) had no postoperative complications at all. The 54 hospital survivors were followed up over a mean period of 12 months (3-36 months). There was one death (eight months postoperatively) and two graft occlusions, not requiring reoperation. At the end of the follow up echocardiography showed that 50 patients (93%) had no (31 patients) or only a very mild Grade I MR (19 patients). Four patients had Grade II MR, none of them requiring mitral valve surgery. All patients improved their NYHA functional class, from 3.4 +/- 0.8 to 1.9 +/- 0.7 and LVEF from 17.9 +/- 4.6 to 44.2 +/- 7.4 (p < 0.001). Coronary artery bypass grafting is a possible treatment for patients with very low LVEF, provided the patient has a two- or three-vessel disease with significant coronary artery stenosis (> 70%) and angina. Mortality and morbidity are low. Moderate co-existing MR (Grade I-III) seems to normalize after myocardial revascularization and should not be surgically corrected therefore at the primary operation.

Adult↗

PubMed1995

Extensive endarterectomy of the left anterior descending coronary artery combined with coronary artery bypass grafting.

BACKGROUND: Complete revascularization of a diffusely diseased left anterior descending (LAD) coronary artery can be accomplished by extensive endarterectomy in conjunction with coronary artery bypass grafting (CABG). The present study was designed to assess the safety of the procedure, and which techniques lead to the best short- and long-term results. METHODS: Between January 1990 and October 1994 106 patients underwent extensive open endarterectomy of the LAD coronary artery combined with CABG at our institution. This group constituted 4.9% of all patients undergoing CABG during this period. The mean age of those studied was 64.4 +/- 9.2 years and 92% were male. In 22 patients (21%) the procedure was a repeat CABG and 12% had had percutaneous transluminal coronary angioplasty prior to the operation. Ninety-one per cent of the patients were in Canadian Cardiovascular Society (CCS) angina class 3 or 4, 91% had three-vessel disease and 36% had unstable angina at the time of surgery. The mean preoperative left ventricular ejection fraction was 53.6 +/- 14.9% (range, 15-80%). The internal mammary artery (IMA) was used to bypass the LAD coronary artery in 40 patients (38%) and a saphenous vein graft (SVG) was used in 66 patients. In 25 of the IMA bypass group an additional venous patch was used (IMA+P). RESULTS: The overall mortality rate was 9.4% (10 patients), including seven immediate postoperative deaths. When the IMA was used as a conduit the mortality rate was only 5.0%. There were seven (6.6%) postoperative non-fatal myocardial infarctions. There was a low incidence of other postoperative complications, similar to that following CABG without endarterectomy performed during the same period. Multivariate analysis identified emergency operation, two-vessel endarterectomy and female sex as independent risk factors for mortality. Upon follow-up study of 94 hospital survivors (98%), at a mean of 26.5 months (range, 1-48 months), all endarterectomy patients were in CCS class 1 or 2. Seventy-eight patients (83%) had an excellent postoperative exercise tolerance and the left ventricular function was preserved. The 4-year survival rates were 88% and 96% and the cardiac event-free survival rates were 74% and 87% in the SVG and IMA groups respectively. CONCLUSIONS: Complete revascularization of the diffusely diseased LAD coronary artery can be accomplished by adjunctive open endarterectomy with a degree of operative risk (mortality 9% and incidence of non-fatal myocardial infarction 7%). The immediate and medium-term results are improved when the IMA is used as a conduit, with or without additional venous patch. Independent risk factors for mortality were two-vessel endarterectomy, female sex and emergency operation. The long-term results revealed an overall survival rate of 92% and a cardiac event-free survival rate of 79% at 4 years, as well as excellent functional results.

Adult↗

PubMed1994

Third-time coronary bypass operation. Analysis of selection mechanisms, results and long-term follow-up.

Twenty-six patients underwent a third coronary artery revascularization between 1984 and 1993 at Hôpital de la Tour, Geneva, Switzerland. These patients represent 5.4% of coronary artery bypass graft (CABG) reoperations and 0.8% of the total CABG operations (3129) during the same time period. There were 23 men (85%), the mean age was 57.2 years (range 33-71), 18 patients (69%) had 3-vessel disease and the mean left ventricular ejection fraction (LVEF) was 59% (range 32-83%). The reason for the third operation was graft failure in 62% of the cases. Twenty-five patients (96%) were in Canadian Cardiovascular Society (CCS) class 3 or 4 preoperatively. Direct myocardial revascularization was performed in all patients with a mean of 3.2 grafts per patient (range 1-6). Thromboendarterectomy was performed in six patients (23%) and patch was used in four (15%). The internal mammary artery (IMA) was utilized in 85% of the patients. In-hospital mortality was 11.5% (3 patients). Non-fatal perioperative myocardial infarction and re-exploration for bleeding did not occur in this group of patients. Respiratory failure necessitating prolonged ventilatory support occurred in five patients (19.2%). Long-term follow-up was carried out for all 23 hospital survivors. The mean follow-up time was 52 months. The 5-year actuarial survival rate was 84.5% for the entire group and 95.7% for hospital survivors. The preoperative CCS functional class had significantly improved at the end of the follow-up, P < 0.001. Our data suggests that a third-time coronary revascularization can be justified, with gratifying operative success and good long-term clinical results.

Adult↗

PubMed1994

Postoperative visceral hypotension the common cause for gastrointestinal complications after cardiac surgery.

In order to identify peroperative risk factors and to evaluate different etiological factors in developing postoperative gastrointestinal complications, clinical variables were studied in 3493 patients undergoing adult cardiac surgery. There were 86 gastrointestinal complications, 2.9%, with an overall morality among these of 22.1%: the mortality rate was 3.9% for all patients undergoing cardiac surgery at our institution (p < 0.001). Paralytic ileus, intestinal ischemia, and acute cholecystitis were the most frequently seen complications. Arterial hypertension, smoking and poor preoperative cardiac function, clinical instability, and the need for an emergency operation were distinct clinical risk factors. Cardiopulmonary bypass time was, by itself, not an important factor. Embolic etiology was also ruled out. The incidence of peroperative myocardial infarction, low postoperative cardiac output necessitating massive use of vasopressor substances and/or intraaortic balloon pumping were significantly more often observed in patients who subsequently developed gastrointestinal complications. The common etiological factor in developing gastrointestinal complications of any kind, after cardiac surgery, seems to be postoperative splanchnic hypoperfusion with visceral ischemia. In order to reduce postoperative morbidity and mortality it is essential to identify patients at risk, support preoperative poor cardiac function, and to carefully monitor these patients postoperatively for abdominal complications to reach an early diagnosis.

Cardiac Surgical Procedures↗

PubMed1994

Valve reoperations--identification of risk factors and comparison with first-time operations.

Fourty-seven patients with a least one heart valve operation each who underwent reoperations (Gr. I) were analyzed with special regard to risk factors influencing the perioperative mortality and compared to 203 patients operated for the first time (Gr. II) during the same time period. Mean age was 57.1 years in Gr. I and 64.1 years in Gr. II (p < 0.05). There were no differences between the groups with regard to sex, smoking, obesity, or concomitant peripheral vascular disease. Hypertension, hyperlipidemia, and diabetes were more frequently seen in Gr. I, p < 0.05. A significantly higher number of patients in the redo group (Gr. I) belonged preoperatively to NYHA class III or IV, p < 0.001 and needed emergency surgery more often, p < 0.01, but left-ventricular function did not differ between the groups. There was no significant difference in the position of valves operated or the number of multiple valve replacements/repairs between the groups, and no difference in aortic cross-clamping or cardiopulmonary bypass time. Most patients were referred from other hospitals. Overall perioperative mortality for Gr. I was 6.4% and Gr. II 4.4% (n.s.). Mortality after first reoperation was 5.0%, after second or more 14.3%. Perioperative mortality was related to age, preoperative NYHA class, and urgency of operation in both groups, and to multiple valve replacement/repair in Gr. I. Elective reoperation carried a mortality of 4.8% but emergency reoperation 20%; reoperation mortality was 2.6% for single valves and 25% for multiple valves.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1994

How safe is coronary bypass surgery in the elderly patient? Analysis of 111 patients aged 75 years or more and 2939 patients younger than 75 years undergoing coronary artery bypass grafting in a private hospital.

AIM AND METHODS: Data from patients younger than 75 years (group I, n = 2939) and patients aged 75 years or older (group II, n = 111) who underwent isolated coronary artery bypass grafting (CABG) during a 9-year period (January 1984 to April 1993) were analyzed to determine comparative risk factors for morbidity, early and late survival, and functional outcome. RESULTS: Traditional risk factors (hypertension, hyperlipidemia, diabetes mellitus, and smoking) were significantly more prevalent in group II. The number of patients in New York Heart Association (NYHA) functional classes 3 and 4 before surgery was also significantly higher in group II (P < 0.001), but emergency operations were equally distributed between the groups. Left main-stem stenosis was more frequent in group II patients (P < 0.01), while the number of vessels involved and pre-operative left ventricular function did not differ. Both groups underwent a mean of 4.5 grafts. Internal mammary grafts were placed in 48.4% (1422/2939) in group I and 19.8% (22/111) in group II (P < 0.001). The overall peri-operative mortality rate did not differ between the groups (2.9% for group I and 2.7% for group II). Non-fatal peri-operative myocardial infarction, ventricular arrhythmias, post-extracorporeal circulation disorientation, and temporary renal insufficiency were more prevalent in group II patients (all P < 0.05). Emergency operations and re-operative CABG increased the peri-operative mortality in both groups. The 3-year survival rate was 93% and the 3-year cardiac event-free rate was 88% for the group II patients. Most of the elderly patients (98%) were in NYHA functional classes 1 and 2 at the end of the follow-up. CONCLUSIONS: Even if elderly patients have a slightly higher postoperative morbidity than younger patients, and an increased mortality if operated upon in an emergency, long-term survival and freedom from cardiac events are excellent and justify the continued performance of CABG in patients aged 75 years of age or more.

Activities of Daily Living↗

PubMed1994

Surgery of the ascending aorta. Analysis of risk factors and results of 30 operations in a private institution.

Replacement of the ascending aorta for aneurysm or dissection remains a complex challenge for cardiac surgeons. Between January 1984 and December 1993, 30 patients have had simultaneous resection of the ascending aorta and aortic valve replacement. Sixteen of them had composite graft replacement of the ascending aorta and the aortic valve with a modified Bentall's technique (Group I). Fourteen patients had supracoronary artery aortic resection and aortic valve replacement (Group II). The mean age was 50.1 +/- 15.3 years (range 23-76). There were 22 men and 8 women. Five patients (16.7%) had aortic dissection, six were operated on an emergency basis. Concomitant coronary artery disease was more frequently seen in Group II (5 patients) than in Group I (1 patient), p < 0.05. Other preoperative patient characteristics did not differ. The overall perioperative mortality was 16.7% (5/30), none of them due to technical complications during surgery. Four patients died in Group I and 1 in Group II (n.s.). Non-fatal myocardial infarction was diagnosed in 1 patient (Group I) and only one neurological complication occurred (Group I), while reexploration for bleeding was performed in 4 cases (13.3%). Four patients in Group I and two in Group II had postoperatively low cardiac output, two of them necessitating intraaortic balloon pump insertion. 43% of the patients had no perioperative complications. At the end of follow-up (n = 25), average 6 months (range 1-52 months), twenty-two survivors (22/25 or 88.0%) were in NYHA functional class 1. Simultaneous ascending aortic aneurysm repair and aortic valve replacement can be accomplished with an acceptable mortality and little morbidity.

Adult↗

PubMed1994

Reoperative myocardial revascularization: an analysis of 458 reoperations and 2645 single operations.

A consecutive series of 2645 patients underwent primary coronary bypass grafting while 458 patients underwent reoperative bypass during a 9-year period. The mean age (61 years), sex distribution (83% men) and preoperative risk factors were identical in the two groups. Significantly more patients belonged to New York Heart Association (NYHA) class 4 and were clinically unstable in the reoperative group (P < 0.001). The internal mammary artery was used in 43% of the single operation group but in only 23% of patients who subsequently required reoperation (P < 0.001). In reoperations 61% of the patients had an internal mammary artery graft (P < 0.001). The overall operative mortality rate for single operation was 2.3% (62/2645) versus 9.2% (42/458) for reoperations. Patients with a reoperative interval of more than 1 year had a 8.4% mortality rate, compared with 28% in those reoperated on 1 year or less after the initial operation (P < 0.01). Preoperative myocardial infarction, intra-aortic balloon pump insertion, prolonged ventilatory support and ventricular arrhythmias were all prevalent after reoperations (all P > 0.001), while postoperative myocardial infarctions and re-sternotomy for bleeding did not differ between the groups. Emergency operation, preoperative NYHA class 3-4 and poor left ventricular function were predictors of perioperative mortality in both groups. Left main stem stenosis was an added factor in the reoperative group. After reoperation 93% of the hospital survivors were alive at 5 years after surgery; the cardiac event-free rate was 59% and > 90% of the patients showed improvement of their NYHA class during the follow-up. Reoperative coronary artery bypass grafting is effective, but has an increased operative mortality and morbidity, especially in patients with unstable angina, left main stem stenosis and poor preoperative left ventricular function.

Adult↗

PubMed1994

A patent internal mammary artery graft decreases the risk of reoperative coronary artery bypass surgery.

In order to evaluate the potential risks of a patent internal mammary artery bypass at reoperative coronary artery bypass grafting, we have reviewed the records of 233 consecutive patients undergoing reoperative coronary artery bypass grafting between 1 January 1991 and 31 December 1993, including 209 patients having an occluded mammary graft or no mammary graft (Group I) and 24 patients having a patent mammary graft (Group II). With regard to preoperative patient characteristics, the only significant differences between the groups were: Group II patients had a higher preoperative left ventricular ejection fraction than did Group I patients (63.7% +/- 8.9% vs. 52.1% +/- 10.1%, p < 0.001); and Group II patients had received fewer grafts per patient than had patients in Group I (2.2 +/- 1.1 vs 3.6 +/- 1.4 grafts per patient, p < 0.001). There were no entry injuries to the grafts or to the heart in either of the groups. No perioperative mortality was encountered in Group II, while 11 patients died in Group I (p < 0.05). Group II had a significantly higher incidence of reexploration for post-operative bleeding, whereas Group I had a significantly higher incidence of low postoperative cardiac output. The incidence of all other perioperative complications did not differ between the groups. The results of this study support the use of mammary grafts even in patients who are likely to need repeat coronary artery bypass grafting and certainly does not disqualify such patients from a 2nd operation.

Coronary Artery Bypass↗

PubMed1994

Gastrointestinal complications after coronary artery bypass grafting.

Clinical variables were studied in 3129 patients undergoing coronary artery bypass grafting to identify patients at risk of abdominal complications and common etiologic factors in the development of such complications. Seventy-three gastrointestinal complications occurred (2.3%), with an overall mortality rate of 16.4% compared with a mortality rate of 3.4% for all patients undergoing bypass grafting (p < 0.001). Cholecystitis and intestinal ischemia were the most frequently encountered complications. Multivariate analysis demonstrated that preoperative hypertension, New York Heart Association classes III and IV, preoperative left ventricular ejection fraction less than 40%, age greater than 70 years, reoperation, and urgent operation as independently and significantly associated with gastrointestinal complications. In contradiction to previous reports, no significant correlation existed between gastrointestinal complications and cardiopulmonary bypass time, 99.8 +/- 35.8 versus 101.2 +/- 39.8 minutes. Perioperative myocardial infarction and immediate postoperative hypotension with low cardiac output necessitating substantial inotropic pharmacologic support or intraaortic balloon pumping were significantly more prevalent in patients who had gastrointestinal complications (all p < 0.001). Furthermore, multivariate analysis revealed that postoperative low cardiac output was a significant, independent predictor in the development of gastrointestinal complications of any kind after coronary artery bypass grafting. Postoperative splanchnic hypoperfusion could therefore be a common etiologic factor.

Adult↗

PubMed1994

Intraoperative use of rtPA for subarachnoid hemorrhage.

Intraoperative thrombolysis with recombinant tissue plasminogen activator (rtPA) was performed in 15 patients with aneurysmal subarachnoid hemorrhage. All patients had significant basal cistern blood accumulation seen on CT scans preoperatively. The patients underwent surgery within four days of subarachnoid hemorrhage with aneurysm clipping in all patients. Postoperatively, transcranial doppler examinations demonstrated reduction in the development of vasospasm to a greater degree in patients treated with rtPA than a similar group of patients managed without the rtPA treatment. Eighty percent of patients receiving intracisternal rtPA had fair to good results compared with 78% of a similar group of patients who underwent surgery shortly after subarachnoid hemorrhage and were not given rtPA. Intracisternal rtPA remains an adjunctive treatment of questionable benefit in the management of patients with aneurysmal subarachnoid hemorrhage.

Adult↗

PubMed1992

Surgical removal of an inferior vena cava thrombus.

Studies on the management of inferior vena cava (IVC) thrombosis have rarely focused upon the risk of later development of post-thrombotic syndrome of the lower limbs. From 1983-1989, 52 patients with ilio-femoral thrombosis with an extension of thrombus into the IVC were treated. In addition to lower limb pain and swelling, 12 (23%) patients had symptomatic pulmonary embolism on admission. Perfusion/ventilation pulmonary scans were positive in 63%. Twelve patients received only anti-coagulant treatment. Thrombectomy was attempted in 40 patients, but failed in 13 patients due to old thrombi. Twenty-seven patients had surgical removal of thrombus combined with anti-coagulation [temporary arterio-venous fistula (AVF) and IVC interruption (n = 15); AVF alone (n = 9); and without fistula n = 3)]. The mortality and morbidity were low and hospital stay was not prolonged. Thirty-eight legs were examined at 7-66 months (mean: 23 +/- 3) after initial treatment. The limbs in which the IVC thrombus could not be removed (n = 20) were symptomatic in 25% of patients, venous ulcer developed in 4 of 20 limbs. The ilio-femoral segment was patent in only 35%. The thrombectomised limbs (n = 18) were asymptomatic in 56%; none had developed ulcer and iliac patency was 72%. Doppler investigations and refilling times were normal in 39% of the thrombectomised limbs. All patients without surgical IVC thrombus removal developed contralateral deep venous thrombosis during the follow-up period. This study shows that femoro-ilio-caval thrombectomy is successful only in patients with a short history and fresh clot, and can be safely performed with low morbidity and mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1992

Intestinal platelet trapping after traumatic and septic shock. An early sign of sepsis and multiorgan failure in critically ill patients?

OBJECTIVES: Patients resuscitated after severe traumatic or septic shock were studied with reference to the behavior of radiolabeled platelets in vital organs, the occurrence of sepsis, and multiorgan failure. These findings were compared with findings of patients who had sustained severe head trauma, but had reportedly not been in shock. DESIGN: Prospective, clinical trial of consecutive patients. SETTING: Multidisciplinary ICU. PATIENTS: Thirteen critically ill patients who were considered at high risk for developing multiorgan failure. These patients had all been resuscitated after major trauma (Injury Severity Score 50.2 +/- 7.2) or severe septic shock (group A, Acute Physiology and Chronic Health Evaluation [APACHE II] score 21.7 +/- 4.4). For comparison, six patients with head trauma, who were considered at low risk for multiorgan failure were studied (group B, Injury Severity Score 26.0 +/- 5.1 and APACHE II score 12.3 +/- 2.4). MEASUREMENTS: Platelet trapping was studied in multiple organs by external detection of platelets labeled with 111indium-oxine. Measurements were started on the third day and continued for seven consecutive days or until death. RESULTS: Eight of 13 patients in group A developed sepsis and multiorgan failure and six of these eight patients died 8 to 29 days after the initial insult. No patient in group B developed multiorgan failure, and all survived. The patients in group A had significant increases in platelet trapping in the liver and the lungs, but the increase was significantly (p less than .01) greater in the nonsurvivors than in the survivors. All the nonsurvivors had markedly increased platelets sequestration in the intestine (less than 10 times the activity in blood), but none of the survivors had increased platelet sequestration in the intestine (p less than .01). This increase was recorded 1 to 4 days before the first clinical signs of sepsis and 3 to 7 days before the development of multiorgan failure. No patient in group B had increased activity in the liver or in the intestine, and only one patient had a slight increase in the lung. CONCLUSIONS: The results indicate that, in patients resuscitated after severe traumatic or septic shock, increased sequestration of platelets in the intestine, as measured by external detection of radioisotope-labeled autologous platelets, may precede clinical signs of sepsis and multiorgan failure and may possibly predict the outcome.

Adult↗

PubMed1992

The effect of low molecular weight dextran on haemodynamics and respiratory function during endotoxin-induced shock.

The effects of low molecular weight dextran (LMWD) infusion, on gas exchange and haemodynamics were evaluated in sheep during endotoxin shock. The infusion of LMWD was started after signs of shock and lung injury were evident. After a stabilization period 10 micrograms kg-1 E. Coli endotoxin was infused i.v.. Endotoxin infusion resulted in an marked increase in pulmonary artery pressure (PAP) and decrease in mean arterial pressure (MAP), respiratory compliance, arterial oxygen tension (PaO2) and oxygen delivery index (DO2l). After 3 h MAP, PaO2, DO2l and compliance improved significantly in LMWD treated animals. The PAP had also decreased significantly in the LMWD-treated animals, but remained high in the controls (P less than 0.01). It was concluded that LMWD infusion improves haemodynamics and gas-exchange in sheep during endotoxin shock.

Animals↗

PubMed1992

Liver cirrhosis induced by carbon tetrachloride and the effect of superoxide dismutase and xanthine oxidase inhibitor treatment.

Repeated administration of carbon tetrachloride (CCl4) induces liver cirrhosis, possibly because it involves the production of free radicals. In order to evaluate the effect of free radical scavengers such as superoxide dismutase (SOD) and allopurinol in the pathogenesis of liver cirrhosis, rats were subjected to repeated CCl4 administration with and without scavengers. Four groups of animals were studied: CCl4 plus SOD (group 1), CCl4 plus allopurinol (group 2), CCl4 alone (group 3) and olive oil (group 4, normal controls). Analysis of plasma and tissue concentrations of trace elements was performed and histopathological patterns were studied in all groups after 7 weeks of repeated intraperitoneal administration of the solutions. Plasma levels of zinc and selenium were significantly lower in all experimental groups, with reciprocal elevation of manganese and copper. Copper and manganese content in the liver tissue was significantly higher in all three experimental groups. The zinc content was elevated in groups receiving CCl4 alone (group 3) or with allopurinol (group 2). The liver selenium, however, was significantly lower in these two groups. The copper:zinc ratio for plasma was 0.78 in the control group, 1.6 in the CCl4 group, 1.3 in the allopurinol group and 1.5 in the SOD group. For liver tissue, the ratio was 0.07 for controls, 0.17 for CCl4, 0.11 for allopurinol and 0.28 for the SOD group. The changes in trace element content correlated with the severity of cellular damage observed microscopically in the liver. The higher the copper:zinc ratio, the more advanced and extensive was the microscopic evidence of liver injury after CCl4 challenge.

Allopurinol↗

PubMed1991

Forskolin impregnation of small calibre PTFE grafts lowers early platelet graft sequestration and improves patency in a sheep model.

Synthetic vascular grafts have a thrombogenic surface which plays a role in graft failure. Systemic pharmacologic interventions have been used to lower platelet sequestration onto the graft surface but are associated with side effects. In this communication we describe the results of a new therapeutic principle of applying forskolin, a powerful cyclic adenosine monophosphate stimulator (cAMP) to the inner surface of PTFE vascular grafts. The grafts were evaluated with Indium-III-oxine labelled platelets and by graft patency on 3 consecutive days after implantation at 1 month and 3 months. Forskolin significantly lowered early platelet sequestration onto the treated graft surface when compared with controls. Graft potency at 1 and 3 months was also significantly higher in the forskolin treated grafts.

Animals↗

PubMed1991

Direct platelet effect of low molecular weight dextran in small calibre PTFE grafts.

The thrombogenicity of synthetic vascular grafts is a major factor in occlusion of grafts when they are used to bypass small calibre arteries. In this paper, the effect of low molecular weight dextran (LMWD, Dextran-40) on graft surface-platelet interaction was studied using Indium-III-oxine labelled platelets. It was found that LMWD significantly reduced platelet deposition onto graft surfaces (P less than 0.001). Dextran had a direct antiplatelet effect independent of plasma volume expansion as dextran-soaked grafts significantly reduced platelet deposition when compared to systemic dextran administration (P less than 0.001). We therefore conclude that LMWD has a direct antiplatelet effect which is beneficial in reducing platelet deposition on synthetic PTFE grafts which may improve the early patency of such grafts.

Animals↗

PubMed1991

Use of indium-111-labeled transferrin to study plasma extravasation during endotoxin shock and the effects of the beta-2 agonist terbutaline.

Endotoxemia and sepsis are common causes of respiratory distress (ARDS), which is characterized by increased pulmonary vascular permeability to plasma proteins resulting in "noncardiac pulmonary edema." The aim of this series was to study the effects of the beta-2 receptor agonist, terbutaline, on plasma extravasation in multiple organs, in sheep exposed to endotoxin shock. A double isotope technique was used and the radioactivity was recorded in different organs (lungs, liver, spleen, kidneys, intestine) by a computerized gamma camera. Tc-99m-labeled erythrocytes were used as a marker for intravascular volume and In-111m-labeled transferrin for tracing extravascular plasma leakage. An organ-transferrin index (organ-TI) was calculated for each organ which corrects for changes in blood distribution. Fourteen sheep were anesthetized and ventilated. After stabilization (t = 0) all animals received E. coli endotoxin 10 micrograms/kg by IV infusion during 30 min. At t = 30, seven animals (group T) received IV infusion of terbutaline, 20 micrograms/kg/hr, during 4 h, while the other seven received normal saline and served as controls (group E). The endotoxin infusion caused an immediate and significant increase in the transferrin index in the lungs and in the liver in both groups. The transferrin index continued to rise in the control group towards the end of the experiment (t = 240), while in group T it reached a maximum 60 min after endotoxin. Four hours after endotoxin the transferrin index was significantly higher in the controls than in the terbutaline treated group, both in the lungs and in the liver (P less than 0.01). No significant changes were recorded in the kidneys or over the intestine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗