Flow measurement in coronary artery surgery.
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Biomedical subjects
Publications and source records attributed to G D'Ancona.
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OBJECTIVE: To determine whether coronary graft patency can be predicted by transit time flow measurement (TTFM). METHODS: From May 1 1997 to December 31 1998, TTFM was prospectively evaluated in 409 patients undergoing coronary artery bypass grafting (CABG) without cardiopulmonary bypass (CPB). All grafts (1145) were tested with TTFM. RESULTS: Thirty-seven out of 1145 grafts (3.2%) were revised in 33 patients (7.6%). In six cases (18.1%) use of CPB was necessary during revision due to hemodynamic instability. The remaining patients underwent revision off-pump. Thirty-four grafts (91.9%) were revised for both low flow and abnormal flow curve patterns. Findings at revision included: thrombosis of the anastomosis (n=6), stenosis at the toe or heel of the anastomosis (n=8), coronary flap or dissection (n=5), dissection of the internal mammary artery (n=5), graft kinking (n=4), flap at proximal anastomosis (n=1), coronary stenosis distal to the graft (n=3), and no findings (n=2). After revision all flow values and flow patterns improved. Although three additional grafts (8.1%) were revised for low flow (<7 ml/min) despite normal flow patterns, there were no findings at revision and flow values and curves remained unchanged after revision. Postoperatively, one patient developed a stroke (3%), one had an acute myocardial infarction (MI) (3%), one had a sternal wound infection (3%), and one required prolonged ventilatory support (3%). CONCLUSION: Evaluation of TTFM is valuable in determining the status of a coronary graft after CABG. Correct interpretation of flow patterns allows for correction of abnormalities prior to chest closure.
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The increasing popularity of beating-heart coronary surgery has raised concerns and doubts about the quality of the coronary anastomoses performed. Intraoperative graft patency verification methods are not commonly used after coronary surgery and, most of the cardiac surgeons, rely on the simple clinical signs (electrocardiogram tracings and hemodynamic stability) to make a diagnosis of coronary graft occlusion. New transit time ultrasound based methods for graft-patency verification have been adopted in many centers during beating-heart and traditional bypass grafting. Although the results are very encouraging, correct interpretation of the flow findings may prove difficult if specific rules are not properly followed. Flow curves, pulsatility index, and flow values should always be considered simultaneously before revising a coronary graft. Measurements should also be always performed with and without a proximal coronary snare. This article summarizes the main features of flowmetry and provides some technical pitfalls and suggestions to achieve an adequate intraoperative flow measurement adopting the transit time method.
Coronary angiography is the gold standard for preoperative diagnosis of coronary artery disease. In reoperative coronary artery surgery the physiologic significance of suspect lesions by angiography can be confirmed by direct intraoperative measurement of blood flow in the old grafts; such interpretation can prevent unnecessary graft revisions.
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BACKGROUND: This retrospective study evaluates morbidity and mortality of reoperative coronary artery bypass grafting (CABG) without cardiopulmonary bypass (CPB) using a posterior thoracotomy to revascularize the lateral aspect of the heart. METHODS: From January 1995 to July 1999, reoperative CABG without CPB was performed on 67 selected patients using a left posterior thoracotomy approach. Preoperative risk factors, postoperative mortality, and major complications were derived from the New York State database. RESULTS: All patients were operated on without CPB. A total of 1.3 grafts per patient were performed. Freedom from major complications was 95.5%. There were no postoperative cerebro-vascular accidents (CVA) or new neurological deficits. Two patients (3%) had a perioperative acute myocardial infarction. The actual mortality rate was 4.5% (3/67), the expected mortality was 5.1% and the calculated risk adjusted mortality was 2.1%. CONCLUSIONS: Reoperative CABG without CPB to revascularize selected coronary artery targets can be safely performed using a posterior thoracotomy approach.
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The Center for Minimally Invasive and Robotic Heart Surgery has performed more than 1,500 off-pump coronary artery bypass (OPCAB) procedures since 1995. The operation has changed significantly based on experience and development of new tools. These improvements have made the operations safer and applicable to more patients. No patients are presently scheduled for on-pump bypass surgery in our center. The purpose of this paper is to describe some of the problems and pitfalls we have experienced and how to avoid them.
BACKGROUND: Many of the modern less invasive approaches to coronary artery bypass grafting (CABG) are performed without the use of the heart lung machine and cardiac asystole. Even after the introduction of mechanical stabilizers, the ability to achieve a technically perfect anastomosis is less certain in beating heart bypass surgery. Our group has begun to assess the surgical results of beating heart CABG using Transit Time Flow Measurement (TTFM). Our experience indicates that a meticulous and controlled method of assessing the results of intraoperative flow measurements can improve the quality of information and increases the accuracy of diagnosing technical problems with newly constructed bypass grafts. For this reason, we developed a standard algorithm for using and interpreting intraoperative TTFM. METHODS: From January to August of 1998, 161 patients underwent off-pump CABG with a total of 323 distal anastomoses (2.0 grafts per patient). All completed grafts were tested intraoperatively with TTFM and the decision to accept or revise any individual graft was based on a decision nomogram using key values readily available from the TTFM output. RESULTS: Thirty-two grafts (9.9%) were surgically revised based on unsatisfactory flow curves, the Pulsatile Index, or both. All revised grafts were found to have a significant technical error, such as an intimal flap, thrombus, conduit kinking, or dissection. There were no major complications, myocardial infarctions, or deaths in the entire series of patients. CONCLUSIONS: Based on our favorable use of TTFM, we strongly recommend that patency of every graft be assessed whether the operation is performed off pump or on cardiopulmonary bypass. Guidelines for performing and interpreting TTFM ensure a high degree of confidence in the completed graft. The decision to revise a graft can be made based on simple parameters easily acquired from the TTFM device. Any concern about quality or quantity of flow should prompt immediate revision.
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BACKGROUND: We have previously shown that a less invasive surgical approach (LISA) can reduce mortality and morbidity in coronary artery bypass grafting (CABG). This appears to have led to the referral of increasingly high risk patients for this procedure as compared to patients undergoing traditional CABG. The purpose of this paper is to compare preoperative risk factors and postoperative complications in both LISA and conventional CABG cases using the New York State database. METHODS: From January 1997 to September 1998, 1,993 patients underwent CABG in our institution: 1,384 with CPB (group A) and 609 without CPB (group B). In group B (LISA), a well defined strategy was followed in an effort to prevent hemodynamic instability during coronary exposure, avoid myocardial ischemia, verify graft patency, and use alternative surgical incisions in reoperations. RESULTS: Analysis of preoperative risk factors using the NYS database showed a significant increase in comorbidities in group B (p < 0.005), while at the same time postoperative complications and risk-adjusted mortality were lower (p = NS). CONCLUSION: Our data demonstrates that by using the LISA, high risk patients can undergo CABG with equal or lower mortality and morbidity than traditional CABG.
From 1990 to 1995, 12 patients with cavo-atrial renal cell carcinoma underwent resection of the tumor. Circulatory arrest was employed in 11/12 cases. The neoplasm extended to the inferior vena cava in two patients and to the intrahepatic veins or right atrium in five cases. Two severely cardiac compromised patients died perioperatively. Of five patients who showed preoperative suspicion of isolated metastases, 3 patients died postoperatively because of relapsing disease after a mean period of 10.8 months. Five patients are alive and doing well after a mean follow-up of 14.8 months. In our experience myocardial dysfunction determined poor immediate survival. Mid-term survival was influenced by preoperative metastases and lymph-node involvement, but not by intracaval extension. Circulatory arrest appears to be a relatively safe technique to remove renal carcinoma with cavo-atrial extension and should be indicated whenever there are no metastases.
The inferior epigastric artery has been proposed as a suitable conduit for myocardial revascularization but its mid-term patency rate has not been assessed. A prospective clinical and angiographic study on the use of the inferior epigastric artery as an additional arterial conduit together with bilateral internal thoracic artery grafting was conducted in 38 patients. No deaths or major postoperative complications occurred. Twenty-three patients underwent repeat angiography after an average of 21.2 months. The left and right internal thoracic artery grafts patency rate was 95.6% (44/46), while inferior epigastric artery patency rate was 52.2% (12/23). By relating patency to the grafted coronary branch, the following results were obtained: 100% for the left anterior descending (3/3), right coronary (1/1) and ramus medianus (1/1); 40% (4/10) and 37.5% (3/8) for diagonals and obtuse marginals respectively. The low patency rates observed when the inferior epigastric artery is used on diagonals and obtuse marginals indicate that this vessel cannot be considered a suitable conduit for extensive application of arterial revascularization. We suggest that the inferior epigastric artery should only be used in patients presenting with contraindications to bilateral internal thoracic artery or right gastroepiploic artery grafting, or exhibiting unsuitable saphenous veins.
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