Cardiovascular surgery (London, England)
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Comparative Study
Reperfusion injury in skeletal muscle: interaction of osmotic and colloid-osmotic pressure in the initial reperfusate for oedema prevention.
Previous studies from the authors' laboratory have shown that controlled limb perfusion after prolonged, acute ischaemia minimizes reperfusion injury. The present study was performed to investigate the role of osmotic and colloid-osmotic pressure in the initial reperfusate in order to reduce postischaemic limb oedema and subsequent reperfusion injury. A total of 96 isolated rat hindlimbs were used: 18 were perfused immediately after amputation (no ischaemia; untreated) and 78 limbs were subjected to 4 h of warm ischaemia in a moist chamber. ⋯ Furthermore, colloid-osmotic pressure > 26 mmHg increases the viscosity of the reperfusate (flow decreases to < 50% of control) and does not allow an optimal functional recovery. Macromolecules used to create the colloid-osmotic pressure should be of similar molecular weight to albumin (69,000 Da); those with a smaller molecular weight (e.g. hydroxyethyl starch40,000/0.5) produce excessive limb oedema (184.9(13.5)% control weight; 85.7(1.4)% water content) without functional recovery (0% control contractions). The present data suggest that after prolonged limb ischaemia: (1) addition of mannitol to a crystalloid solution does not prevent oedema; (2) hyperosmotic reperfusates (380-480 mosmol/l) with a colloid-osmotic pressure of 26 mmHg are most effective in preventing limb oedema; and (3) macromolecules used to achieve colloid-osmotic pressure should have a molecular weight similar to albumin.
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Between January 1990 and September 1992, ten patients required assisted circulation for postcardiotomy heart failure which was unresponsive to inotropic drugs and aortic counterpulsation. All patients were supported by a Bio-Medicus centrifugal pump (biventricular assist in five, left ventricular in three, right ventricular in two); six had ischaemic heart disease, two a congenital ventricular septal defect, one an acute mitral valve incompetence and one an aortic type 'A' dissection. The mean duration of circulatory support was 5.1 days (range 2 hours to 8 days). ⋯ Common complications were bleeding (40%), acute renal failure (30%) and sepsis (30%). All patients who developed renal failure died. The high incidence of haemorrhagic complications makes the use of pre-heparinized circuits desirable as these patients do not then require additional anticoagulation.
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Ten patients (eight men, two women) who underwent surgical reconstruction of the superior vena cava using an expanded polytretrafluoroethylene (ePTFE) prosthesis between 1981 and 1991 were reviewed to assess the therapeutic value of such surgery. The mean (s.d.) age was 55(12) years. Obstruction of the superior vena cava was caused by pulmonary or mediastinal cancer in nine patients and chronic mediastinitis in one. ⋯ Eight patients died. The cumulative survival rates were 70, 25 and 12.5% at 1, 2 and 5 years, respectively. Surgical reconstruction of the superior vena cava with an ePTFE prosthesis provided immediate and long-term relief of symptoms of superior vena cava obstruction with a low surgical morbidity, even in patients with unresectable malignancy.
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Clinical Trial
Treatment of thoracic outlet syndrome with combined scalenectomy and transaxillary first rib resection.
Of a total of 225 patients with suspected thoracic outlet syndrome, 37 (16.4%) underwent surgery. Some eight patients required bilateral operations. One patient had a cervical rib and one a prominent C7 transverse process. ⋯ Similar results were achieved in the patients' subjective evaluation with approximately 50% reporting an excellent outcome, about 40% good and 10% fair. A poor result was not recorded in those who underwent combined scalenectomy and transaxillary first rib resection. A radical surgical approach combining scalenectomy and transaxillary first rib resection is advocated to minimize the recurrence rate and improve results.
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This study evaluated the use of monitoring blood levels of the isoenzyme of creatine phosphokinase, troponin T (tnT) and myosin in the detection of perioperative myocardial damage after coronary artery surgery. Serial blood samples were collected in 24 patients undergoing myocardial revascularization. The patients were retrospectively divided into three groups: group A with no changes in their electrocardiogram; group B showing non-specific signs of perioperative myocardial infarction such as deep and permanent T wave inversion; and group C with definite electrocardiographic signs of perioperative myocardial infarction (new persistent Q-waves and loss of R-waves). ⋯ Peak values of troponin T and myosin in groups B and C were statistically different from those in group A (P < 0.001). These results suggest that troponin T and myosin are reliable indicators of perioperative myocardial damage. In particular, troponin T may allow the differentiation of reversible from irreversible myocardial injury.