Direct comparison between cerebral oximetry by INVOS(TM) and EQUANOX(TM) during cardiac surgery: a pilot study.

INTRODUCTION: Several near-infrared spectroscopy oximeters are commercially available for clinical use, with lack of standardization among them. Accordingly, cerebral oxygen saturation thresholds for hypoxia/ischemia identified in studies conducted with INVOS(TM) models do not necessarily apply to other devices. In this study, the measurements made with both INVOS(TM) and EQUANOX(TM) oximeters on the forehead of 10 patients during conventional cardiac surgery are directly compared, in order to evaluate the interchangeability of these two devices in clinical practice. METHODS: Cerebral oxygen saturation measurements were collected from both INVOS(TM) 5100C and EQUANOX(TM) 7600 before anesthetic induction (baseline), two minutes after tracheal intubation, at cardiopulmonary bypass onset/offset, at aortic cross-clamping/unclamping, at the end of surgery and whenever at least one of the two devices measured a reduction in cerebral oxygen saturation equal to or greater than 20% of the baseline value. Bland-Altman analysis was used to compare the bias and limits of agreement between the two devices. RESULTS: A total of 140 paired measurements were recorded. The mean bias between INVOS(TM) and EQUANOX(TM) was -5.1%, and limits of agreement were ±16.37%. Considering the values as percent of baseline, the mean bias was -1.43% and limits of agreement were ±16.47. A proportional bias was observed for both absolute values and changes from baseline. CONCLUSIONS: INVOS(TM) and EQUANOX(TM) do not seem to be interchangeable in measuring both absolute values and dynamic changes of cerebral oxygen saturation during cardiac surgery. Large investigations, with appropriate design, are needed in order to identify any device-specific threshold.

Fenoldopam to prevent renal replacement therapy after cardiac surgery. Design of the FENO-HSR study.

INTRODUCTION: Acute kidney injury requiring renal replacement therapy is a serious complication following cardiac surgery associated with poor clinical outcomes. Until now no drug showed nephroprotective effects. Fenoldopam is a dopamine-1 receptor agonist which seems to be effective in improving postoperative renal function. The aim of this paper is to describe the design of the FENO-HSR study, planned to assess the effect of a continuous infusion of fenoldopam in reducing the need for renal replacement therapy in patients with acute kidney injury after cardiac surgery. METHODS: We're performing a double blind, placebo-controlled multicentre randomized trial in over 20 Italian hospitals. Patients who develop acute renal failure defined as R of RIFLE score following cardiac surgery are randomized to receive a 96-hours continuous infusion of either fenoldopam (0.025-0.3 µg/kg/min) or placebo. RESULTS: The primary endpoint will be the rate of renal replacement therapy. Secondary endpoints will be: mortality, time on mechanical ventilation, length of intensive care unit and hospital stay, peak serum creatinine and the rate of acute renal failure (following the RIFLE score). CONCLUSIONS: This trial is planned to assess if fenoldopam could improve relevant outcomes in patients undergoing cardiac surgery who develop acute renal dysfunction. Results of this double-blind randomized trial could provide important insights to improve the management strategy of patients at high risk for postoperative acute kidney injury.

Angiographic anatomy of the grafted left internal mammary artery.

BACKGROUND: The hypothesis that persistence of undivided branches is a common finding after myocardial revascularization using the left internal mammary artery was explored. METHODS: Three hundred seven consecutive postoperative angiographies of the left internal mammary artery were considered. Seven were excluded because of occlusion or malfunction of the conduit or the anastomosis. Of the remaining 300, 150 were harvested through a left anterior small thoracotomy (group A) and 150 through a median sternotomy (group B). The persistence of undivided branches was recorded for each group. RESULTS: Common origin with other branches of the subclavian artery was present in 55 patients in group A and 54 in group B (p = not significant); the persistence of lateral costal branch was also equally distributed in both groups (15 and 17; p = not significant). The first intercostal artery was present in 5 patients in group A and in none in group B (p = not significant). Branches of 1 mm or more were more frequent in group A (34 versus 4, p < 0.001), as well as branches of less than 1 mm (140 versus 67; p < 0.001). Only 2 patients in group A had no branches versus 48 patients in group B (p < 0.001). CONCLUSIONS: Common origin with other branches of the subclavian artery and persistence of the lateral costal branch are common aspects in the angiographic anatomy of the grafted left internal mammary artery. Moreover, new branches, sometimes wider than 1 mm, develop with time. These findings are independent from the harvesting technique, the left anterior small thoracotomy, or the median sternotomy. If flow competition between the coronary and noncoronary territories was a reality, coronary artery grafting with the left internal mammary artery would be unsuccessful since the beginning.

Current results in off pump surgery.

OBJECTIVE: We reviewed our experience with myocardial revascularization without cardiopulmonary by-pass (CPB) to evaluate early- and mid-term results compared with those obtained using CPB. METHODS: From May 21, 1997 to November 1998, 747 patients had isolated myocardial revascularization, 480 without CPB (Group A) and 267 with CPB (Group B). Exposure of the target vessels was obtained with four slings (two passed through the transverse sinus and two behind the inferior vena cava) and four deep pericardial sutures on the mobile pericardium around the left atrium (Lima stitches). The number of anastomoses/patient (when two or more conduits were used) was higher in Group B (3.1 +/- 1.0 vs 2.6 +/- 0.7, P < 0.001). More marginal branches were grafted in Group A (258 vs 239), but the percentage was higher in Group B (P < 0.001). Crude and risk adjusted mortality was similar in both groups, as well as cerebrovascular accident (CVA) and acute myocardial infarction incidences. Patients in Group A woke earlier, had less inotropes, lower creatinkinase myocardial band (CK-MB) peak, lower bleeding and less transfusion, shorter Intensive Care Unit (ICU) and postoperative stay in hospital than patients in Group B. 266 anastomoses were checked; of these 98.5% were patent and 97.0% were patent and not restrictive. CONCLUSIONS: Myocardial revascularization without CPB can provide good early- and mid-term results in selected patients. Primary endpoints (death and acute myocardial infarction) were similarly independent from the technique used. Some of the secondary endpoints were favorable in Group A: however their importance is minor. Even if we feel that some high risk patients with severe comorbidities can benefit from CPB surgery; this aspect is difficult to demonstrate scientifically.

Off or on bypass: what is the safety threshold?

BACKGROUND: To identify the technical profile of the patients operated on without cardiopulmonary bypass (CPB) and the benefit of the procedure. METHODS: From May 21, 1997, to December 31, 1998, 785 patients had coronary artery bypass grafting through a median sternotomy (group A: 472 without CPB; group B: 290 with CPB; group C: 23 converted). Technical aspects, mortality rate, cerebrovascular accident (CVA) incidence (crude and risk-adjusted), and incidence of major complications were recorded. RESULTS: Patients without CPB had mainly one to three grafts and one- or two-vessel disease. Multiple arterial grafting was not a limit, whereas sequential grafting was. Group A had lower complications rates, shorter intensive care unit and postoperative in hospital stays, and lower transfusion rates. Mortality rates and CVA incidence (crude and risk-adjusted) were similar in both groups and in each subgroup considered. In group A, a lower complications rate was present in some patients (aged greater than 70 years, female, with unstable angina). Group C showed higher mortality and complications rates. Failure of revascularization showed no difference between groups. CONCLUSIONS: Primary endpoints are not affected by the surgical strategy, whereas some of the secondary endpoints are. However, patients in group A experienced fewer complications. Both techniques can give satisfying results and must be applied according to the surgeon's preference.

Minimally invasive mammary artery Doppler flow velocity evaluation in minimally invasive coronary operations.

BACKGROUND: Left internal mammary artery Doppler flow velocity assessment during the Azoulay maneuver (patient's legs are passively lifted up and actively maintained by the patient) can increase the information on the anastomosis quality after left internal mammary artery to left anterior descending coronary artery grafting after the left anterior, small thoracotomy operation. METHODS: One hundred patients had an early postoperative angiography and a Doppler flow velocity assessment at rest and during the Azoulay maneuver. Peak and mean systolic velocities, peak and mean diastolic velocities, and peak and mean diastolic to systolic velocity ratios were recorded in all patients. RESULTS: In 95 patients with no restrictive conduit or anastomosis, peak and mean diastolic to systolic velocity ratios increased during the Azoulay maneuver; all but 1 patient showed at least one ratio equal to or greater than 1. In 4 patients with restrictive conduit or anastomosis, peak and mean diastolic to systolic velocity ratios were always less than 1 during the Azoulay maneuver. In the patient with an occluded conduit these ratios were less than 0.6. CONCLUSIONS: Peak and mean diastolic to systolic velocity ratios less than 1 during the Azoulay maneuver are suggestive of conduit or anastomosis malfunction. If we limit the angiographic controls to these patients, it is very likely that a pathologic anastomosis or conduit will not be missed.

The LAST operation: techniques and results before and after the stabilization era.

BACKGROUND: Left anterior descending artery stabilization allows performance of left internal mammary artery grafting via a left anterior small thoracotomy on a beating heart. Our surgical experience was reviewed to assess if surgical results have improved as result of specialized instrumentation. METHODS: Of 545 patients who had the left anterior small thoracotomy operation, 261 underwent this procedure for single left anterior descending artery disease. Two groups were considered, before and after the use of specialized instrumentation: group A (n = 93), operated on from November 21, 1994, to April 20, 1996; and group B (n = 168), operated on from April 21, 1996, to December 1997. RESULTS: Early mortality was similar in the two groups. The further revascularization (operation or percutaneous transluminal coronary angioplasty) and the rate of occlusion of the conduit were higher in group A, whereas anastomotic or conduit malfunction was not. Cumulating angiography and Doppler flow evaluation, 92.5% of the anastomoses in group A and 98.8% in group B (p = 0.026) were patent, and 90.3% in group A and 97.6% in group B (p = 0.031) were patent and not restrictive. At 19 months, survival was similar, but the event-free survival was higher in group B. CONCLUSIONS: Both left anterior descending artery stabilization and safer left internal mammary artery harvesting contributed to improve angiographic and clinical results after the left anterior small thoracotomy operation.

Midterm results after minimally invasive coronary surgery (LAST operation)

BACKGROUND: Our experience with a left internal thoracic artery graft to the left anterior descending artery via a left anterior small thoracotomy is reviewed to evaluate midterm results. METHODS: From November 1994 to April 1997, four hundred sixty patients were scheduled to undergo a left internal thoracic artery graft to the left anterior descending coronary artery via a left anterior small thoracotomy; 26 of these patients (5.7%) were converted and 434 of them had the operation. Two hundred fourteen patients (49.3%) had isolated disease of the left anterior descending artery, and 220 patients (50.7%) had multiple vessel disease. A sufficient length of the left internal thoracic artery was harvested to reach the left anterior descending artery. RESULTS: Three hundred nine patients (71.2%) underwent extubation by hour 2. Mean intensive care unit stay was 4.2 +/- 4.5 hours; mean postoperative hospital stay was 66 +/- 29 hours; the 30-day mortality rate was 1.1%; the late mortality rate was 1.4%. Eighteen patients underwent reoperation early (< or = 30 days), and eight patients underwent reoperation late (> 30 days) because of conduit/anastomotic malfunction. Four patients underwent reoperation with patent anastomosis for progression of disease (n = 3) or pericarditis (n = 1). Three patients had a percutaneous transluminal coronary angioplasty. Cumulating angiographic and stress Doppler flow assessment results, a patent anastomosis was obtained in 417 patients and a nonrestrictive anastomosis in 404 patients. Twenty-nine months after surgery, survival was 97.1% +/- 0.7% (95% confidence interval 90.5% to 100%) and event-free survival 89.4% +/- 1.2% (95% confidence interval 78.2% to 100%). In the last 190 patients, with our increased experience and better instruments, we obtained a patent anastomosis in 188 patients (98.9%) and a nonrestrictive anastomosis in 185 (97.4%). CONCLUSIONS: Left anterior small thoracotomy gives acceptable midterm results. Incidence of patent and nonrestrictive anastomoses was satisfactory, especially in the most recent part of our experience, when the learning curve ended.

Left anterior small thoracotomy (LAST): mid-term results in single vessel disease.

BACKGROUND: Left anterior descending artery grafting using the left internal mammary artery via a left anterior small thoracotomy (LAST) gained new popularity in 1994. We review our experience in 250 of 512 patients who underwent a LAST in single vessel left anterior descending artery disease from November 1994 to October 1997. METHODS: Left anterior descending artery stabilization was obtained pharmacologically and mechanically. Two patients (0.8%) had percutaneous transluminal coronary angioplasty at a mean of 23 +/- 5 days; 172 (68.8%) patients had early postoperative angiography. RESULTS: Eight conduits were occluded (patency rate 95.3%). There was only one late death. Cumulative angiography and Doppler flow evaluation showed that 96.8% of the anastomoses were patent and 95.6% were both patent and nonrestrictive. At a mean follow-up of 16.3 +/- 9.3 months, 9 (3.6%) patients had redo-surgery due to anastomotic/conduit failure and 249 (99.6%) patients were alive and asymptomatic. No patients had acute myocardial infarction. The 35-month actuarial survival rate was 99.6% +/- 0.4%, and the event-free survival rate for the entire experience was 93.7% +/- 1.3%. If only the last 157 patients are considered, at 18 months event-free survival was higher than in the entire group of patients (96.4% +/- 1.4% vs 93.7% +/- 1.3%, p = 0.05). CONCLUSIONS: New instrumentation has made the operation easier and has contributed to its spread, along with increased experience and the end of the learning curve. At the moment we consider the LAST a more anatomical and physiological surgical approach to single vessel coronary disease.

Minimally invasive coronary artery bypass grafting on a beating heart.

BACKGROUND: We reviewed our experience with left internal mammary artery (LIMA)-to-left anterior descending artery (LAD) anastomosis on a beating heart through a left anterior small thoracotomy. METHODS: This procedure was performed in 343 of 358 scheduled patients; in 15 (4.2%) the LAD was not suitable or was too small. The chest was opened in the fourth (127, 37.0%) or fifth (197, 57.4%) intercostal space, or both (19, 5.6%); the length of the harvested LIMA was 4-15 cm. The LAD was occluded by means of two 4-0 Prolene (Ethicon, Somerville, NJ) sutures, both snared on a small piece of silicone tubing. The anastomosis was performed with two 8-0 Prolene sutures. In the early postoperative period all patients underwent angiography or a doppler flow assessment of the LIMA or both. RESULTS: In 310 patients the LIMA was connected directly to the LAD; to elongate the LIMA, in 30 patients an inferior epigastric artery and in 3 patients a saphenous vein was used. In 2 patients the diagonal branch was also grafted using an inferior epigastric artery from the LIMA. Three patients (0.9%) died during the first 30 days after the operation, and 4 other patients (1.2%) died after the first month. Twenty-five patients (7.3%) were reoperated on because of anastomotic or conduit failure, 18 (5.2%) early and 7 (2.1%) late; one additional patient had a late percutaneous transluminal coronary angioplasty for anastomotic stenosis. At a mean of 9.5 +/- 5.7 months of follow-up, 336 patients (98.0%) were alive, asymptomatic with or without medical treatment, and without cardiac events. COMMENT: Left internal mammary artery-to-LAD anastomosis performed on a beating heart through a left anterior small thoracotomy is a procedure that can be performed with low risk and acceptable midterm results in selected patients.