Effects of centrifugal and roller pumps on survival of autologous red cells in cardiopulmonary bypass surgery.

BACKGROUND: Either a roller pump or a centrifugal pump can be used in the extracorporeal circuit during surgery with cardiopulmonary bypass. In this study, we assessed the effect of these two pumps on the 24-h post-transfusion survival values of autologous red blood cells (RBC). STUDY DESIGN AND METHODS: Fourteen male patients subjected to extracorporeal bypass procedures were studied. In seven patients, the autologous red cells were collected following the cardiopulmonary bypass procedure using the roller pump, and in seven patients, autologous red cells were collected following the cardiopulmonary procedure using the centrifugal pump. The 24-h post-transfusion survival values of the autologous RBC were measured using the 51 disodium chromate/99m technetium double isotope procedure. The effects of the extracorporeal bypass procedures using the roller pump and the centrifugal pump were also assessed by the measurements of hematocrit, platelet count, plasma hemoglobin, and serum lactate dehydrogenase levels. RESULTS: The 51 disodium chromate 24-h post-transfusion survival values of the autologous RBC were similar whether the roller pump or the centrifugal pump was used in the extracorporeal circulation, as were the hematocrit, platelet count, plasma hemoglobin and serum lactate dehydrogenase levels. CONCLUSION: The 24-h post-transfusion survival values of autologous RBC, measured by the 51 disodium chromate/99m technetium double isotope procedure, were not significantly different, whether the roller pump or the centrifugal pump was used in the extracorporeal circuit using membrane oxygenators during cardiopulmonary surgical procedures.

Endoscopic radial artery harvest: a new approach.

BACKGROUND: Although early attempts to use the radial artery (RA) as a conduit for cardiac revascularization met with disappointing results, recent data have shown the RA to achieve very good short-term patency as well as promising mid-term patency results. The recent increase in the frequency of coronary reoperations, with their limited options for vascular conduits, has also stimulated an interest in the RA graft. The success of minimally invasive vein harvesting techniques encouraged us to develop a minimally invasive technique for harvesting the RA from the forearm, which is reviewed in this article. METHODS: The endoscopic harvest technique was employed on more than 120 nonselected patients at our facility over a 12-month period. The procedure involved exposure of the RA under direct visualization and without direct manipulation, using an endoscopic dissector and harmonic shears. Side branches of the RA were isolated and divided, and the vessel was removed and side branch occlusion verified. The harvested RA was then prepared for the revascularization surgery. RESULTS: The patients who underwent the procedure showed no evidence of graft spasm or occlusion in the immediate postoperative period. Patients also preferred the small endoscopic incision to the full forearm incision of the "open" technique. CONCLUSIONS: Our experience indicates that endoscopic radial artery harvesting is a safe technique that achieves good short-term patency results and improved patient satisfaction. Evaluation of long-term vessel integrity is needed, and a comparison of the minimally invasive and the open technique has been initiated.

Chronic effects of arterial balloon dilatation on internal mammary artery endothelial function.

BACKGROUND: Manipulation for harvesting of the internal mammary artery (IMA) for coronary artery bypass grafting has been shown to acutely impair endothelium-dependent, but not endothelium-independent contractions and relaxations. Recently the use of a novel arterial balloon catheter to dilate the IMA has shown an increased IMA flow while preserving endothelial cell integrity and function acutely. This study examines the chronic effects on endothelial function of IMA segments subjected to arterial balloon catheter dilatation in comparison to either no manipulation (control), luminal dilatation with papaverine, or temporary occlusion with soft or hard jaw in a porcine model. METHODS: Porcine IMAs were harvested one month after instrumentation. Ten IMA segments in each group were obtained and placed in organ chambers under isometric tension. Maximal endothelium-dependent contractions with arachidonic acid and relaxations with acetylcholine, and endothelium-independent contractions with norepinephrine and relaxations with sodium nitroprusside were measured. RESULTS: Endothelium-dependent contractions and relaxations were significantly impaired after hard jaw occlusion one month after IMA manipulation compared to control, long balloon, fibrous jaw, and papaverine groups. Endothelium-independent contractions and relaxations of IMA smooth muscle were unaffected at one month after manipulation. CONCLUSION: We conclude that arterial long balloon dilatation is not detrimental to endothelial cell function chronically and is therefore an effective and atraumatic method to relieve IMA spasm before coronary bypass grafting.

Arterial balloon catheter: a new atraumatic device for dilating arterial grafts.

BACKGROUND: Harvesting of the internal mammary artery (IMA) for use in myocardial revascularization may result in spasm, which can impair early graft flow. Hydrostatic and mechanical dilatation can exert an intraluminal shear force, causing denudation of the IMA endothelium. A new long balloon dilatation technique (LB) has been developed to mechanically increase IMA diameter and flow without exerting any shear force on the endothelium. METHODS: Vascular rings of porcine IMA were divided into four groups: no manipulation (control), metal dilators (MD), short balloon (SB), or LB intraluminal dilation. In situ flows after dilation and percentage of intact endothelium after silver nitrate staining were determined. Endothelium-dependent contractions with arachidonic acid, relaxations with acetylcholine, endothelium-independent contractions with norepinephrine, and relaxation with sodium nitroprusside were recorded in organ chamber experiments. RESULTS: Increases in IMA flows were similar in all dilated groups. Endothelium-independent contractions and relaxations of IMA smooth muscle were unaffected by any type of mechanical dilation. However, endothelium-dependent contractions and relaxations were significantly impaired after MD and SB but preserved after LB dilation compared with control. Silver nitrate staining showed a greater preservation of the endothelial coverage after LB dilation. CONCLUSIONS: IMA dilatation with the novel arterial LB catheter increases IMA flow and preserves endothelial cell integrity, making it an effective and atraumatic method to relieve IMA spasm before use for coronary artery bypass grafting.

Integrated myocardial revascularization.

The integration of minimally invasive coronary artery bypass grafting with catheter-based interventions is being practiced with increasing frequency both in the standard and high risk patient populations. The procedures can be staged on different days or done concurrently in either an operative cathlab or an operating room with imaging capabilities. The new clinical issues raised with these new approaches are reviewed for practitioners considering adopting this new treatment strategy.

Initial experience with MIDCAB grafting using the gastroepiploic artery.

BACKGROUND: Minimally invasive direct coronary artery bypass grafting with the gastroepiploic artery can be used in primary operations and reoperations to revascularize the inferior or anterior surface of the heart. METHODS: Patients who had symptomatic coronary artery disease limited to a single coronary distribution were selected. Coronary targets were grafted with the pedicled gastroepiploic artery through a small midline epigastric incision. Patients were followed with scheduled outpatient clinic visits, Doppler examination, and selective recatheterization. RESULTS: Between May 1995 and November 1997, 74 patients underwent gastroepiploic artery minimally invasive direct coronary artery bypass grafting; 33 (45%) had a primary operation and 41 (55%), a reoperation. Grafting was performed to the distal right coronary artery (n = 38), the posterior descending artery (n = 28), or the distal left anterior descending coronary artery (n = 8). There were six deaths (8%) within 30 days after operation. Twenty patients (28%) underwent recatheterization; there were two graft occlusions, two graft stenoses, and five anastomotic stenoses. Of 60 patients seen 2 or more weeks after operation, 53 (88%) had resolution of anginal symptoms at a mean follow-up of 10.9 months (range, 0 to 30 months). CONCLUSIONS: Inferior minimally invasive direct coronary artery bypass grafting with the gastroepiploic artery avoids the risks of repeat sternotomy, aortic manipulation, and cardiopulmonary bypass. Patency rates, however, were lower than expected, and there is significant morbidity and mortality associated with high-risk patients undergoing the procedure. Continued follow-up is essential to evaluate long-term graft patency and patient survival.

Early experience with minimally invasive direct coronary artery bypass grafting with the internal thoracic artery.

OBJECTIVE: Minimally invasive direct coronary artery bypass is performed under direct vision without sternotomy or cardiopulmonary bypass. The technique can be used in both primary and reoperative cases by employing the internal thoracic artery to perform arterial revascularization of the anterior surface of the heart. METHODS: Patients were selected who had significant coronary artery disease limited to 1 or 2 coronary distributions on the anterior surface of the heart. Coronary target vessels were grafted with the internal thoracic artery through a small anterior thoracotomy. After partial heparinization the anastomosis was facilitated by local coronary occlusion and handheld stabilization. RESULTS: Between August 1994 and July 1997, 162 patients underwent minimally invasive direct coronary artery bypass grafting with the internal thoracic artery. The left and right internal thoracic arteries were used for grafting of the left anterior descending artery in 142 patients (88%), the proximal right coronary artery in 7 patients (4%), existing saphenous vein grafts in 5 patients (3%), and diagonal branches in 2 patients (1%). Sequential grafting with the left internal thoracic artery was performed in 2 patients (1%) and bilateral internal thoracic artery grafting was performed in 4 patients (3%). Eight patients (4.9%) died within 30 days after the operation, 3 of cardiac causes. Seven additional patients died during the follow-up period. Nine patients (5.6%) required reintervention for graft stenosis or occlusion during follow-up. Of 141 patients seen 2 or more weeks after the operation, 135 (96%) had resolution of their anginal symptoms at a mean follow-up of 12 months (range 0-31 months). CONCLUSIONS: Anterior minimally invasive direct coronary artery bypass grafting with the internal thoracic artery avoids the risks of repeated sternotomy, aortic manipulation, and cardiopulmonary bypass. There was a low rate of reintervention, and patients had excellent resolution of anginal symptoms. Postoperative length of stay was comparatively short, and continued follow-up will be essential to evaluate long-term graft patency and patient survival.

Noninvasive graft flow and patency assessment following minimally invasive direct coronary artery bypass (MIDCAB) grafting.

OBJECTIVE: Assessment of graft patency following minimally invasive direct coronary artery bypass (MIDCAB) surgery is essential in order to determine the efficacy of this technique. This study was conducted to evaluate the role of intraoperative and postoperative noninvasive flow and velocity measurements to follow and predict graft performance. METHODS: Between April 1996 and July 1997, 130 patients had 133 grafts placed using MIDCAB techniques. Intraoperative transit-time ultrasound was used to assess graft patency and flow prior to wound closure. Also, serial transcutaneous doppler examinations were performed to evaluate graft patency on the first postoperative day, at two weeks, and at three months. Peak values for systolic and diastolic waveforms were measured for both flow and velocity, and the diastolic-to-systolic ratio was calculated at each time interval. Recatheterization was performed selectively for inadequate ultrasound flow or doppler velocity, or for patient symptoms. RESULTS: Seven (5.3 %) grafts developed stenosis or occlusion. When compared to normal grafts, mean intraoperative flows, flow ratios, and velocity ratios were lower. Mean postoperative diastolic peak velocity (DPV) to systolic peak velocity (SPV) ratio remained stable over time for normal grafts; however, grafts with stenosis or occlusion demonstrated a diminished DPV/SPV ratio. CONCLUSIONS: Intraoperative transit-time ultrasound and outpatient transcutaneous doppler examinations did not reach a predictive value for graft stenosis or occlusion following MIDCAB surgery in this series of patients. However, these data demonstrate trends that may help identify patients at an increased risk for unfavorable events, guiding the use of postoperative recatheterization in such patients.

The expanded role of minimally invasive coronary grafting.

The evolution of minimally invasive direct coronary artery bypass (MIDCAB) grafting has extended the role of this approach for limited coronary revascularization. MIDCAB techniques can now be used to address isolated stenoses in the inferior and lateral coronary distributions. MIDCAB techniques are increasingly being used in the reoperative setting, and multiple vessels can be bypassed during a single operation. This article reviews the expanded role of MIDCAB grafting in the treatment of coronary artery disease.

Reoperative MIDCAB grafting: 3-year clinical experience.

OBJECTIVE: Minimally invasive direct coronary artery bypass (MIDCAB) is performed under direct vision without sternotomy or cardiopulmonary bypass. The technique is used in reoperative patients through various incisions to revascularize one or two areas of the heart. The internal mammary artery, gastroepiploic artery, radial artery, or saphenous vein are used as graft conduits. METHODS: Anterior coronary targets are grafted with the internal mammary artery via a small anterior thoracotomy. Inferior coronary targets are grafted with the gastroepiploic artery via a small midline epigastric incision. Lateral coronary targets are grafted with radial artery or saphenous vein via a posterior thoracotomy. After partial heparinization, the anastomosis is facilitated by local coronary occlusion and stabilization. Graft follow-up consists of outpatient Doppler examination and selective recatheterization. RESULTS: Between January 1994 and August 1997, 81 patients underwent reoperative MIDCAB grafting. Twenty-one patients (25.9%) had internal mammary grafting, 39 (48.2%) had gastroepiploic grafting, and 21 (25.9%) had lateral grafting with radial artery or saphenous vein. There were nine early deaths (four cardiac, five non-cardiac), five late deaths (three cardiac, two non-cardiac), and nine myocardial infarctions in remaining patients. Sixteen patients underwent recatheterization; there were one graft occlusion, two graft stenoses, and eight anastomotic stenoses. Mean postoperative length of stay was 3.8 days. Ninety percent (55/61) of patients are free of symptoms at a mean follow-up of 7.8 months (range 0-39). CONCLUSIONS: Reoperative MIDCAB grafting avoids the risks of resternotomy, aortic manipulation, and cardiopulmonary bypass. The techniques yield an early patency rate of 94%, which includes eight patients who had postoperative catheter-based interventions. Reoperative MIDCAB grafting had lower rates of supraventricular arrhythmia and transfusion when compared with conventional coronary artery bypass grafting, but did not offer an advantage for mortality, stroke or myocardial infarction. This 3-year experience suggests that while reoperative MIDCAB grafting can effectively revascularize focal areas of the heart, patients should be carefully selected to minimize operative risk.

Minimally invasive atrial septal defect closure using the subxyphoid approach.

BACKGROUND: Atrial septal defects in adults are associated with paradoxical emboli, atrial tachyarrythmias, and congestive heart failure. Surgical closure is highly efficacious with low operative mortality and morbidity. However, in young women sternotomy scars are unsightly reminders of an otherwise curative procedure. Alternatives such as lateral thoracotomy or extended transverse incisions are more cosmetic but associated with breast maldevelopment, numbness and other side effects. The authors are proposing a new surgical approach based on their observation that the right atrium and septum actually lie only 1 inch superior to the xyphisternal junction. METHODS: A 4 inch transverse inframammary incision is used and the linea alba divided. The lower sternum is lifted forward with a commericial cable-pully retractor system (Rultract). Using femoral bypass augmented by a balloon tipped cannula in the superior vena cava, the septal defect is easily visualized and closed with conventional techniques and equipment. RESULTS: Two young women have undergone closure of a patent foremen ovale (N=1) and a large ostium secundum (N=1) defect through this approach. One patient had minor fat necrosis in the incision which subsequently healed without incident. CONCLUSIONS: Close anatomic proximity between the atrial septum and the lower sternum make it feasible to approach ostium secundum defects using a purely subxyphoid exposure. Visualization of the defect is excellent without the need for thoractomy and sternotomy. The use of a small transverse incision in the inframammary crease makes the result cosmetically invisible.

Cost analysis of current therapies for limited coronary artery revascularization.

BACKGROUND: Single or double (limited) coronary artery revascularization using percutaneous transluminal coronary angioplasty (PTCA) and coronary artery bypass (CAB) surgery has recently been enhanced with further innovation in intracoronary stenting and the emergence of minimally invasive direct coronary artery bypass (MIDCAB) grafting. Resource allocation for all modalities is directly dependent on hospitalization costs, length of stay, and clinical results. METHODS AND RESULTS: Four groups of 25 consecutive patients over 9 months at a single center received either PTCA, stenting, MIDCAB, or conventional CAB for single-vessel coronary disease, primarily of the left anterior descending circulation. Day, supply, and procedural charges were evaluated, along with the total hospital charge. Postprocedural length of stay was calculated and compared with a national database. MIDCAB surgery day charges were less than stenting but greater than PTCA, MIDCAB supply charges were the least of all groups, and MIDCAB procedural charges were less than for conventional CAB. Total charges for MIDCAB grafting were less than for stenting but greater than for PTCA. Postprocedural length of stay for MIDCAB patients was equivalent to PTCA patients and significantly less than for stenting or for conventional CAB. CONCLUSIONS: MIDCAB grafting provides a new surgical approach that is comparable in charges to catheter-based interventions. The technique markedly reduces length of stay and perioperative morbidity. The selection of medical or surgical limited coronary revascularization can now be based primarily on clinical outcomes without consideration for associated resource allocation.

Lateral MIDCAB grafting via limited posterior thoracotomy.

OBJECTIVE: Minimally invasive direct coronary artery bypass (MIDCAB) is a technique for coronary artery bypass grafting performed under direct vision without sternotomy or cardiopulmonary bypass. The approach has been used principally for primary single vessel grafting of the anterior or inferior coronary circulation. This initial experience presents a new lateral technique for patients with isolated circumflex coronary disease which can be used for both primary and reoperative revascularization with either saphenous vein or a free radial artery conduit. METHODS: Lateral MIDCAB grafting of the circumflex coronary circulation was accomplished over a 33 month period at a single center using saphenous vein or free radial artery as the bypass conduit. Through a limited posterior thoracotomy, the lung is deflated and reflected superiorly. The pericardium is opened below the phrenic nerve to expose an obtuse marginal branch of the circumflex coronary artery. After heparinization, the coronary artery is temporarily occluded proximally and distally with local immobilization and an arteriotomy is performed. The distal anastomosis with running suture is followed by the proximal anastomosis on the descending aorta below the hilum of the lung using a side-biting clamp and radiopaque marker. Intraoperative transit time ultrasound flow measurements confirm adequate graft flow before wound closure. RESULTS: To date, 19 patients have undergone this procedure with a mean follow-up of 12 months. A total of 12 patients received saphenous vein grafts and 7 patients received radial artery grafts. There was one death from arrhythmia on postoperative day 9. There was one elective conversion to conventional sternotomy due to inadequate exposure. Graft flows averaged 33.3 cc/min (range 5-87) and the mean postoperative length of stay was 4.5 days; 4 patients underwent recatheterization; 1 had graft occlusion and 2 received late postoperative catheter-based interventions. All patients are currently free of symptoms. CONCLUSIONS: Lateral MIDCAB grafting provides focused revascularization to the circumflex distribution in both primary and reoperative settings. This approach avoids the hazards of resternotomy, eliminates cardiopulmonary bypass, and hastens postoperative recovery. These early results suggest the technique is effective at relieving symptoms and minimizing perioperative morbidity. Further experience at multiple centers will serve to define the ultimate capabilities of this new approach.

One-month histologic response of transmyocardial laser channels with molecular intervention.

BACKGROUND: Transmyocardial revascularization reduces the symptoms and morbidity of patients with endstage ischemic heart disease. The mechanism is postulated to be the formation of transmural left ventricular channels through which oxygenated blood directly perfuses the myocardium. New techniques for molecular enhancement of angiogenesis and endothelial cell motility may represent strategies to augment this clinical benefit. METHODS: Triads of transmyocardial revascularization channels were placed in eight separate nonischemic sites on the hearts of 7 pigs weighing 68 to 78 kg, which were allowed to recover and were then sacrificed at 28 days. In addition, one triad pair was injected with vascular endothelial growth factor, and two triad pairs received an adenovirus vector with or without the gene encoding for human profilin, which increases endothelial cell motility and adhesion. The remaining triad pair stood untreated (laser only). The histologic changes were graded (0 through 3) by an independent pathologist without knowledge of the treatment modality. Profilin production and vascular endothelial growth factor activation using a tyrosine kinase assay were monitored. RESULTS: Transmyocardial revascularization alone resulted in a significant injury response (p < 0.01), including increased vascularity without patent channels. Vascular endothelial growth factor increased surrounding inflammation (p < 0.01) without improving vascularity or patency. Profilin content in tissues was increased but nonspecifically because inflammation resulting from adenovirus also induces higher profilin concentrations. CONCLUSIONS: The clinical benefit of transmyocardial revascularization may result simply from a nonspecific histologic response to injury. Molecular interventions appear to stimulate more inflammation but no additional angiogenesis. Further improvement in the clinical benefit of transmyocardial revascularization awaits the successful stimulation of a true angiogenic response.