Adding water to liquid scintillation cocktail for laboratory wipe tests.

As part of an ongoing laboratory survey process improvement program, we evaluated the addition of water to liquid scintillation cocktail to improve wipe test counting efficiency. Both polar and non-polar 3H and 14C-labeled compounds were used as model contaminants. Our results support the recommendations in the literature regarding the addition of water to scintillation cocktail We found an increase in the counting efficiency of the water-soluble material as a function of water content of the cocktail, but also observed a decrease in the efficiency of detection of the non-polar compound. The offsetting effects are believed to be the result of increased solubility of the polar compounds in water and increased quench of the already solubilized non-polar compound. The finding that adding water to the cocktail brought counting efficiencies of both polar and non-polar molecules to roughly the same value is novel and allows the use of a single quench curve for each radionuclide, regardless of chemical form.

Bilateral internal mammary artery grafting in women: a 21-year experience.

BACKGROUND: Coronary artery bypass grafting traditionally has carried a higher mortality rate in women than in men. It remains the leading cause of death in women despite major advances in diagnosis and treatment over the past 2 decades. METHODS: A retrospective analysis was conducted to identify risk factors that adversely influence hospital mortality, morbidity, and long-term clinical results in women undergoing bilateral internal mammary artery grafting. From January 1972 through October 1994, 327 consecutive women received bilateral internal mammary artery grafts and supplemental vein grafts. Patient age ranged from 32 to 84 years (mean, 65.7 years). There were 262 patients (80.1%) with three-vessel disease; 71 (21.7%) had substantial (> 50%) stenosis of the left main coronary artery, 65 (19.9%) had a moderately reduced (0.30 to 0.50) ejection fraction, and 11 (3.4%) had a severely reduced (< 0.30) ejection fraction. Preoperatively, 316 patients (96.6%) were in New York Heart Association class III or IV. RESULTS: There were 1,016 coronary artery grafts (mean, 3.1 per patient). The overall hospital mortality rate was 3.4% (11 of 327). Postoperative complications included myocardial infarction in 18 patients (5.5%), stroke in 5 (1.5%), pulmonary insufficiency in 11 (3.4%), reoperation for bleeding in 7 (2.1%), and sternal infection in 8 (2.4%). Independent predictors of operative death were postoperative cardiac arrest (p < 0.001), use of intraaortic balloon pump (p < 0.001), and reoperation for bleeding (p < 0.050). Follow-up was completed on 316 hospital survivors (100%) and ranged from 6 months to 21 years (mean, 5.1 years). Actuarial survival (mean +/- standard error of the mean) was 90.5% +/- 1.9% at 5 years and 65.6% +/- 6.1% at 10 years. At follow-up, 252 patients (94.0%) were asymptomatic in New York Heart Association class I, and 12 (4.5%) were in class II. CONCLUSIONS: This longitudinal study demonstrates that bilateral internal mammary artery grafting, though technically demanding, can be achieved in women with low hospital mortality and morbidity rates. Patients experienced reduced late cardiac events, excellent functional improvement, and enhanced long-term survival.

Coronary bypass grafting in the elderly. Single versus bilateral internal mammary artery grafts.

A surgical experience between October 1983 and December 1990, with 1467 consecutive patients 65 years of age and over, was used to compare patients receiving single internal mammary artery grafts (n = 736) with those receiving bilateral internal mammary artery grafts (n = 731). The mean age in the single-graft group was 73.2 years and 70.9 years in the bilateral-graft group (p < 0.001). Various clinical parameters were analyzed that revealed that the single-graft group had more women and more patients with unstable angina, a history of previous myocardial infarction, and emergency surgery (p < 0.05). There was no significant difference in cigarette smoking, hypertension, diabetes mellitus, hyperlipidemia, triple vessel coronary artery disease, left main coronary artery stenosis, or left ventricular function between the two groups. Hospital mortality for the single-graft group was 6.4% (47 patients) and 3.1% (23 patients) for the bilateral-graft group (p < 0.004). No significant difference was observed between the groups in the rate of reoperation for bleeding, sternal infection, respiratory failure, stroke, or perioperative infarction. Follow-up was obtained in 663 hospital survivors (96.4%) in the single-graft group and in 691 (97.7%) in the bilateral-graft group. Mean follow-up in the single-graft group was 42.5 months (range, 1 to 92.4 months) and 43.0 months (range, 1 to 90.3 months) in the bilateral-graft group. In the single-graft group, survival was 60.7% +/- 4.8% (+/- standard error of the mean) at 8 years (60 patients at risk); it was 67.9% +/- 8.1% (18 patients at risk) for the bilateral-graft group (p < 0.028). This comparative study demonstrates that bilateral internal mammary artery grafting can be accomplished in elderly patients with low operative risk and hospital morbidity. Moreover, patients in both groups had a reduction in cardiac events and significant functional improvement.

Bilateral internal mammary artery grafts in patients with left main coronary artery disease.

The use of the internal mammary artery (IMA) in myocardial revascularization has been expanded with bilateral and sequential grafting. However, its application in the presence of left main coronary artery stenosis (LMCAS) has not been well established. From September 1983 through December 1990, 280 patients with LMCAS greater than 50% were revascularized (3.4 mean grafts per patient) with bilateral IMA and saphenous vein grafts. Eighty-one were sequential IMA grafts. There were 234 males (83.6%) and 46 females (16.4%) with a mean age of 64.4 years (range 39 to 84 years). Preoperatively, there were six patients (2.1%) in New York Heart Association (NYHA) Class I, 30 patients (10.7%) in Class II, 130 patients (46.4%) in Class III, and 114 patients (40.7%) in Class IV. Fifty-six patients (20.0%) had an ejection fraction less than 50%. Intraaortic balloon counterpulsation was used preoperatively in 26 patients (9.3%) and intraoperatively in 11 patients (3.9%). There were four hospital deaths (1.4%). Hospital complications included: reoperation for bleeding, 7 patients (2.5%); pulmonary insufficiency, 21 patients (7.5%); perioperative infarction, 14 patients (5.0%); and stroke, 4 patients (1.4%). Follow-up was obtained in 276 hospital survivors (100.0%) with a mean of 33.4 months. There were 20 late deaths (7.1%): seven cardiac related and 12 noncardiac related. Postoperative assessment reveals substantial functional improvement. These results furnish evidence that bilateral IMA grafts can be accomplished with a low operative risk and can provide excellent functional results in patients with LMCAS.

Bilateral internal mammary artery grafts in reoperative and primary coronary bypass surgery.

Bilateral internal mammary artery grafting is recognized as a preferred method of myocardial revascularization. However, its efficacy in coronary bypass reoperation has not been clearly established. From January 1982 through June 1989, 88 patients underwent coronary bypass reoperation with bilateral internal mammary artery grafts. Results were compared with those for a subset of 88 patients receiving primary revascularization with bilateral internal mammary artery grafts who were computer matched for sex, age, left ventricular function, anginal classification, and left main coronary artery disease. In each group, 62.5% (55 patients) had unstable angina, 43.2% (38 patients) had reduced ejection fraction, and 21.6% (19 patients) in the reoperation group and 20.5% (18 patients) in the reference group had left main coronary artery disease. Hospital mortality for the reoperation group was 6.8% (6 patients) and for the reference group, 3.4% (3 patients). No significant difference was found in the incidence of reoperation for bleeding, sternal infection, or stroke in the two groups. The incidence of respiratory insufficiency in the reoperation group was 13.6% (12 patients) and in the reference group, 3.4% (3 patients) (p less than 0.015). Recurrent angina occurred in 13.7% (10 patients) of patients in the reoperation group and 13.3% (10 patients) in the reference group. The long-term survival at 5 years for the reoperation group was 85.3% +/- 5.6% (+/- standard error of the mean) and for the reference group, 91.6% +/- 3.1%. No significant difference was found in the equality of survival distribution for the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Seventeen-year experience with bilateral internal mammary artery grafts.

The internal mammary artery (IMA) is being recognized as the conduit of choice for myocardial revascularization. From January 1972 through June 1988, 1,087 patients received bilateral IMA and supplemental vein grafts. There were 917 men (84.4%) and 170 women (15.6%) with a mean age of 62.4 years (range, 29 to 84 years). Three hundred ninety-four patients (36.2%) had unstable angina, and 194 (17.8%) had left main coronary artery stenosis greater than 50%. In all, 3,741 coronary grafts were performed, with a mean of 3.4 per patient. Hospital mortality was 2.7% (29 patients). Hospital complications included reoperation for bleeding, 19 patients (1.7%); sternal infection, 16 patients (1.5%); respiratory failure, 35 patients (3.2%); perioperative myocardial infarction, 22 patients (2.0%); and stroke, 20 patients (1.8%). Post-operative arteriography in 53 patients (mean postoperative time, 53.0 months) showed that 92.1% (58/63) of the left IMA and 84.9% (45/53) of the right IMA grafts were patent. Follow-up was completed on 1,058 hospital survivors. There were 82 late deaths (7.8%). The actuarial survival for patients discharged from the hospital was 80.0 +/- 3.2% (plus or minus standard error of the mean) at 10 years and 60.0% +/- 5.0% at 15 years. At follow-up, 866 patients (90.3%) were asymptomatic and in New York Heart Association class I and 68 (7.1%) were in class II. This longitudinal analysis demonstrates that bilateral IMA grafting has a low operative risk and provides excellent long-term functional improvement and survival.

Twelve-year experience with bilateral internal mammary artery grafts.

A 12 1/2-year experience with 227 patients who underwent coronary revascularization with bilateral internal mammary artery (IMA) and supplemental saphenous vein grafts is presented. There were 725 coronary grafts performed (3.2 per patient). Forty-four IMA grafts were sequential. In 42 patients, the right IMA was placed through the transverse sinus to revascularize the circumflex artery. Operative mortality was 4% (9 of 227 patients). Postoperative complications included sternal infection (4 patients), reexploration for bleeding (5), and diaphragmatic dysfunction (10). Postoperative arteriography in 30 patients (mean interval, 4 1/4 years) revealed that 92% (34/37) of the left IMA and 87% (26/30) of the right IMA grafts were patent. Late follow-up was complete in 207 surviving patients. Eighteen late deaths (9 cardiac and 9 noncardiac) occurred. Actuarial survival was 83% at 10 years after operation. Of 68 patients followed from 8 to 12 1/2 years (mean interval, 10 1/2 years), 69% were asymptomatic, and 28% were in New York Heart Association Functional Class II. We conclude that bilateral IMA grafting can be accomplished with low operative risk and provides excellent long-term results.