Initial misinterpretation of a transesophageal echocardiographic image: potential for alteration of a planned minimally invasive procedure.
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Anesthesia↗
Biomedical subjects
L C Siegel
Publications and source records attributed to L C Siegel.
Coronary sinus catheterization for minimally invasive cardiac surgery.
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Cardiac Surgical Procedures↗
Hematocrit value on intensive care unit entry influences the frequency of Q-wave myocardial infarction after coronary artery bypass grafting. The Institutions of the Multicenter Study of Perioperative Ischemia (McSPI) Research Group.
OBJECTIVES: No data exist regarding "the best" hematocrit value after coronary artery bypass graft surgery. Transfusion practice varies, because neither an optimal hematocrit value nor a uniform transfusion trigger criterion has been determined. METHODS: To investigate the optimal hematocrit value, we studied 2202 patients undergoing coronary bypass. The hematocrit value on entry into the intensive care unit (IHCT) was categorized into three groups: high (> or = 34%), medium (25% to 33%), and low (< or = 24%). Characteristics and adverse events (outcomes) were compared, and the effect of IHCT on the risk of myocardial infarction was determined by logistic regression. RESULTS: High IHCT (> or = 34%) was associated with an increased rate of myocardial infarction (8.3% vs 5.5% vs 3.6%; p < or = 0.03, high, medium vs low) and with more severe left ventricular dysfunction (11.7% vs 7.4% and 5.7%; p=0.006, high, medium vs low). Mortality rate increased with higher IHCT when all the high-risk subgroups were combined (8.6% vs 4.5% vs 3.2%; p < 0.001, high, medium vs low). By multivariate analysis, IHCT remained the most significant predictor of adverse outcomes (relative risk high vs low 2.22, 95% confidence interval: 1.04 to 4.76). No characteristic, event, medication, or transfusion therapy confounded the relationship between IHCT and outcome. CONCLUSION: High IHCT is associated with a higher rate of myocardial infarction and is an independent predictor of infarction. On the basis of the risk of myocardial infarction, there is no rationale for transfusion to an arbitrary level after coronary artery bypass grafting.
Anemia↗
Variability in transfusion practice for coronary artery bypass surgery persists despite national consensus guidelines: a 24-institution study. Institutions of the Multicenter Study of Perioperative Ischemia Research Group.
BACKGROUND: An estimated 20% of allogeneic blood transfusions in the United States are associated with cardiac surgery. National consensus guidelines for allogeneic transfusion associated with coronary artery bypass graft (CABG) surgery have existed since the mid- to late 1980s. The appropriateness and uniformity of institutional transfusion practice was questioned in 1991. An assessment of current transfusion practice patterns was warranted. METHODS: The Multicenter Study of Perioperative Ischemia database consists of comprehensive information on the course of surgery in 2,417 randomly selected patients undergoing CABG surgery at 24 institutions. A subset of 713 patients expected to be at low risk for transfusion was examined. Allogeneic transfusion was evaluated across institutions. Institution as an independent risk factor for allogeneic transfusion was determined in a multivariable model. RESULTS: Significant variability in institutional transfusion practice was observed for allogeneic packed red blood cells (PRBCs) (27-92% of patients transfused) and hemostatic blood components (platelets, 0-36%; fresh frozen plasma, 0-36%; cryoprecipitate, 0-17% of patients transfused). For patients at institutions with liberal rather than conservative transfusion practice, the odds ratio for transfusion of PRBCs was 6.5 (95% confidence interval [CI], 3.8-10.8) and for hemostatic blood components it was 2 (95% CI, 1.2-3.4). Institution was an independent determinant of transfusion risk associated with CABG surgery. CONCLUSIONS: Institutions continue to vary significantly in their transfusion practices for CABG surgery. A more rational and conservative approach to transfusion practice at the institutional level is warranted.
Blood Component Transfusion↗
Monitoring considerations for port-access cardiac surgery.
BACKGROUND: A method for monitoring patients was evaluated in a clinical trial of minimally invasive port-access cardiac surgery with closed chest endovascular cardiopulmonary bypass. METHODS AND RESULTS: Cardiopulmonary bypass was conducted in 25 patients through femoral cannulas. An endovascular pulmonary artery vent was placed in the main pulmonary artery through a jugular vein. For mitral valve surgery, a catheter was placed in the coronary sinus for delivery of cardioplegia. A balloon catheter ("endoaortic clamp," EAC) used for occlusion of the ascending aorta, delivery of cardioplegia, aortic root venting, and pressure measurement was inserted through a femoral artery and initially positioned by use of fluoroscopy and transesophageal echocardiography (TEE). Potential migration of the EAC was monitored by (1) TEE of the ascending aorta, (2) pulsed-wave Doppler of the right carotid artery, (3) balloon pressure, (4) comparison of aortic root pressure and right radial artery pressure, and (5) fluoroscopy. TEE, fluoroscopy, and pressure measurement were effective in monitoring catheter insertion and position. With inadequate balloon inflation, migration of the EAC toward the aortic valve could be detected with TEE. During administration of cardioplegia, TEE showed movement of the balloon away from the aortic valve, and migration into the aortic arch was detectable with loss of carotid Doppler flow. Stability of EAC position was demonstrated with appropriate balloon volume. Cardioplegic solution was visualized in the aortic root, and aortic root pressure changed appropriately during administration of cardioplegia. Venous cannula position was optimized with TEE and endopulmonary vent flow measurement. CONCLUSIONS: An effective method has been developed for monitoring patients and the catheter system during port-access cardiac surgery.
Cardiopulmonary Bypass↗
Closed-chest cardiopulmonary bypass and cardioplegia: basis for less invasive cardiac surgery.
BACKGROUND: We developed a method of closed-chest cardiopulmonary bypass to arrest and protect the heart with cardioplegic solution. This method was used in 54 dogs and the results were retrospectively analyzed. METHODS: Bypass cannulas were placed in the right femoral vessels. A balloon occlusion catheter was passed via the left femoral artery and positioned in the ascending aorta. A pulmonary artery vent was placed via the jugular vein. In 17 of the dogs retrograde cardioplegia was provided with a percutaneous coronary sinus catheter. RESULTS: Cardiopulmonary bypass time was 111 +/- 27 minutes (mean +/- standard deviation) and cardiac arrest time was 66 +/- 21 minutes. Preoperative cardiac outputs were 2.9 +/- 0.70 L/min and postoperative outputs were 2.9 +/- 0.65 L/min (p = not significant). Twenty-one-French and 23F femoral arterial cannulas that allowed coaxial placement of the ascending aortic balloon catheter were tested in 3 male calves. Line pressures were higher, but not clinically limiting, with the balloon catheter placed coaxially. CONCLUSIONS: Adequate cardiopulmonary bypass and cardioplegia can be achieved in the dog without opening the chest, facilitating less invasive cardiac operations. A human clinical trial is in progress.
Animals↗
Port-access cardiac operations with cardioplegic arrest.
BACKGROUND: A less invasive approach to cardiac surgery has been propelled by recent advances in video-assisted surgery. Previous obstacles to minimally invasive cardiac operations with cardioplegic arrest included limitations in operative exposure, inadequate perfusion technology, and inability to provide myocardial protection. METHODS: Port-access technology allows endovascular aortic occlusion, cardioplegia delivery, and left ventricular decompression. The endoaortic clamp is a triple-lumen catheter with an inflatable balloon at its distal end. Antegrade cardioplegia is delivered through a central lumen, which also acts as an aortic root vent, a second lumen is used as an aortic root pressure monitor, and a third lumen is used for balloon inflation to provide aortic occlusion. RESULTS: Experimental and clinical studies have demonstrated the feasibility of port-access coronary artery bypass grafting and port-access mitral valve procedures. Endovascular cardiopulmonary bypass using the endoaortic clamp was effective in achieving cardiac arrest and myocardial protection to allow internal mammary artery to coronary artery anastomosis in a still and bloodless field. Intracardiac procedures, such as mitral valve replacement or repair, have been successfully performed clinically. CONCLUSION: The port-access system effectively achieves cardiopulmonary bypass and cardioplegic arrest, thereby enabling the surgeon to perform cardiac procedures in a minimally invasive fashion. This system provides for endovascular aortic occlusion, cardioplegia delivery, and left ventricular decompression.
Cardiac Surgical Procedures↗
Minimally invasive right heart operations: techniques for bicaval occlusion and cardioplegia.
Peripheral cardiopulmonary bypass with cardioplegia has facilitated minimally invasive coronary artery bypass grafting and mitral valve replacement. The cardiopulmonary bypass system was modified to allow bicaval occlusion for right heart operations. In 4 canine studies, three variants of bicaval cannulation techniques were successfully used for atrial septal defect repair via a right minithoracotomy.
Animals↗
Extracorporeal circulation for port-access cardiac surgery.
Minimally invasive techniques for cardiac surgery are a new approach in performing some cardiac operations. Minimally invasive surgery may minimize patient discomfort, length of stay in the hospital and postoperative rehabilitation. These procedures utilize a small thoracotomy for direct visualization of the heart. However, without the use of cardiopulmonary bypass, this approach is limited to some epicardial procedures such as coronary bypass grafting, where the heart rate is pharmacologically reduced. Port-access cardiac surgery is a new approach which provides all the benefits of minimally invasive surgery without sacrificing the advantages of cardiopulmonary bypass and myocardial preservation. Port-access cardiac surgery uses an anterior mediastinotomy and thoracic ports in conjunction with a specially designed set of endovascular catheters. These catheters provide a mode to arrest, preserve and vent the heart through an endoaortic occlusion balloon positioned in the ascending aorta. A pulmonary artery vent and coronary sinus cardioplegia catheter can also be used. These endovascular catheters, integrated with a modified heart-lung machine, provide complete cardiopulmonary support through extrathoracic cannulae inserted in a femoral artery and vein. Maintenance and monitoring of this endovascular cardiopulmonary bypass system requires the use of a kinetic pump in the venous drainage line to augment return to the heart-lung machine. Special guidelines and management parameters exist to optimize bypass with this catheter system. Using this system, port-access, minimally invasive surgery can be applied to a wider range of both epicardial and intracardiac procedures.
Cardiac Surgical Procedures↗
Port-access mitral valve replacement in dogs.
OBJECTIVE: The objective was to assess mitral valve replacement in a minimally invasive fashion by means of port-access technology. METHODS: Fifteen dogs, 28 +/- 3 kg (mean +/- standard deviation), were studied with the port-access mitral valve replacement system (Heartport, Inc., Redwood City, Calif.). Eleven dogs underwent acute studies and were sacrificed immediately after the procedure. Four dogs were allowed to recover and then were sacrificed 4 weeks after operation. Cardiopulmonary bypass was conducted by femoral cannulation with an endovascular balloon catheter for aortic occlusion, root venting, and antegrade delivery of cardioplegic solution. Catheters were inserted in the jugular vein for pulmonary artery venting and retrograde delivery of cardioplegic solution. Through the oval port, a prosthesis (St. Jude Medical, Inc., St. Paul, Minn., or CarboMedics, Inc., Austin, Texas) was inserted through the left atrial appendage and secured to the anulus with sutures. Deairing was performed. RESULTS: Cardiopulmonary bypass duration was 114 +/- 24 minutes and aortic crossclamp time was 68 +/- 14 minutes. All animals were weaned from cardiopulmonary bypass in sinus rhythm. Cardiac output and pulmonary artery occlusion pressure were unchanged (2.8 +/- 0.7 L/min and 7 +/- 3 mm Hg before operation vs 2.6 +/- 0.6 L/min and 9 +/- 4 mm Hg after operation). There was no mitral regurgitation according to left ventriculography in 13 of 15 dogs. In two dogs there was interference with prosthetic valve closure by residual native anterior leaflet tissue. Pathologic examination otherwise showed normal healing without perivalvular discontinuity. Microscopic studies showed no damage to the valve surfaces. Transthoracic echocardiography of the four dogs in the long-term study showed normal ventricular and prosthetic valve function 4 weeks after the operation. CONCLUSION: Mitral valve replacement with a minimally invasive method has been demonstrated in dogs. A clinical trial is in progress.
Animals↗
Minimally invasive cardiopulmonary bypass with cardioplegic arrest: a closed chest technique with equivalent myocardial protection.
Thoracoscopic cardiac surgery is presently under intense investigation. This study examined the feasibility and efficacy of closed chest cardiopulmonary bypass and cardioplegic arrest in comparison with standard open chest methods in a dog model. The minimally invasive closed chest group (n = 6) underwent percutaneous cardiopulmonary bypass and cardiac venting, as well as antegrade cardioplegic arrest through use of a specially designed percutaneous endovascular aortic occluder and cardioplegic solution delivery system. The control group (n = 6) underwent standard sternotomy and conventional open chest cardiopulmonary bypass, aortic crossclamping, and antegrade cardioplegia. Ischemic arrest time was 1 hour in each group. Ventricular pressures and sonomicrometer segment lengths were recorded before bypass and at 30 and 60 minutes after bypass. Left ventricular function did not differ significantly between the two groups, as demonstrated by measurements of elastance and end-diastolic stroke work. Also, the preload recruitable work area was 69% and 60% of baseline at 30 and 60 minutes after bypass in the minimally invasive group versus 65% and 62% in the conventional control group (p = not significant); the stroke work end-diastolic length relationship was 78% and 71% of baseline in the minimally invasive group at these intervals versus 77% and 74% in the conventional control group (p = not significant). Myocardial temperatures were similar throughout bypass in the two groups, and ultrastructural examination of prebypass and postbypass biopsy specimens showed no differences between groups. These results demonstrate that minimally invasive cardiopulmonary bypass with cardioplegic arrest is as feasible, safe, and effective as conventional open chest cardiopulmonary bypass. Thus current technology may allow wider clinical application of closed chest cardiac surgery.
Analysis of Variance↗
Port-access coronary artery bypass grafting: a proposed surgical method.
Minimally invasive surgical methods have been developed to provide patients the benefits of open operations with decreased pain and suffering. We have developed a system that allows the performance of cardiopulmonary bypass and myocardial protection with cardioplegic arrest without sternotomy or thoracotomy. In a canine model, we successfully used this system to anastomose the internal thoracic artery to the left anterior descending coronary artery in nine of 10 animals. The left internal thoracic artery was dissected from the chest wall, and the pericardium was opened with the use of thoracoscopic techniques and single lung ventilation. The heart was arrested with a cold blood cardioplegic solution delivered through the central lumen of a balloon occlusion catheter (Endoaortic Clamp; Heartport, Inc., Redwood City, Calif.) in the ascending aorta, and cardiopulmonary bypass was maintained with femorofemoral bypass. An operating microscope modified to allow introduction of the 3.5x magnification objective into the chest was positioned through a 10 mm port over the site of the anastomosis. The anastomosis was performed with modified surgical instruments introduced through additional 5 mm ports. In the cadaver model (n = 7) the internal thoracic artery was harvested and the pericardium opened by means of similar techniques. A precise arteriotomy was made with microvascular thoracoscopic instruments under the modified microscope on four cadavers. In three other cadavers we assessed the exposure provided by a small anterior incision (4 to 6 cm) over the fourth intercostal space. This anterior port can assist in dissection of the distal internal thoracic artery and provides direct access to the left anterior descending, circumflex, and posterior descending arteries. We have demonstrated the potential feasibility of grafting the internal thoracic artery to coronary arteries with the heart arrested and protected, without a major thoracotomy or sternotomy.
Anastomosis, Surgical↗
Leftward deviation of the interatrial septum during left heart bypass for repair of a thoracic aortic aneurysm.
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Aged↗
Delayed time response of the continuous cardiac output pulmonary artery catheter.
Previous studies of the accuracy of pulmonary artery catheters (PAC) which provide continuous cardiac output (CCO) monitoring have investigated the performance during steady-state conditions. We compared the response time to hemodynamic change using a CCO PAC and an ultrasonic flow probe (UFP). In five sheep, a CCO PAC was inserted, and an UFP for measurement of CCO was placed around the pulmonary artery via a left thoracotomy. Six interventions which rapidly alter cardiac output were studied: crystalloid bolus, balloon inflation in the inferior vena cava (IVC), IVC balloon deflation, dobutamine infusion, hemorrhage, and reinfusion of blood. Cardiac output measured before and after each intervention was used to calculate the total change caused by the intervention, and the time intervals from intervention to 20%, 50%, and 80% of that change were noted. For all interventions, the time response of CCO was significantly slower than UFP. The largest differences were seen with the rapid infusion of lactated Ringer's solution for which the time interval for 20% change was 7.3 +/- 2.3 min (mean +/- SD) for CCO versus 0.5 +/- 0.3 min for UFP. The time interval for 80% change was 14.5 +/- 4.1 min for CCO versus 1.8 +/- 0.9 min with UFP. The current study demonstrates clinically important time delays in the response of the CCO catheter. This delay must be considered when rapid alterations of the hemodynamic state may occur.
Adrenergic beta-Agonists↗
Port-access coronary artery bypass with cardioplegic arrest: acute and chronic canine studies.
BACKGROUND: Our goal is to perform minimally invasive coronary artery bypass grafting without sacrificing the benefits of myocardial protection with cardioplegia. METHODS: Twenty-three dogs underwent acute studies and 4 dogs underwent survival studies. The left internal mammary artery was taken down using a thoracoscope. Cardiopulmonary bypass was conducted via femoral cannulas and using an endovascular balloon catheter for ascending aortic occlusion, root venting, and delivery of antegrade blood cardioplegia. Pulmonary artery venting was achieved with a jugular vein catheter. An internal mammary artery-to-coronary artery anastomosis was performed using a microscope through a 10 mm port. RESULTS: All animals were weaned from cardiopulmonary bypass in sinus rhythm without inotropes. Cardiopulmonary bypass duration was 104 +/- 28 minutes and aortic clamp duration was 61 +/- 22 minutes. Cardiac output and pulmonary artery occlusion pressure were unchanged. The internal mammary artery was anastomosed to the left anterior descending artery (25) or the first diagonal (2) with patency shown in 25 of 27. One dog in the survival study had a very short internal mammary artery pedicle under tension and was euthanized for excessive postoperative hemorrhage. Three weeks postoperatively the remaining dogs had angiographically patent anastomoses, normal transthoracic echocardiograms, and histologically normal healing and patent grafts. CONCLUSIONS: Endovascular cardiopulmonary bypass using a balloon catheter is effective in arresting and protecting the heart to allow thoracoscopic internal mammary artery-to-coronary artery anastomosis.
Animals↗
Echocardiographic monitoring of minimally invasive mitral valve surgery using an endoaortic clamp.
BACKGROUND AND AIMS OF THE STUDY: Twenty-four patients underwent minimally invasive mitral valve repair (n = 16) or mitral valve replacement (n = 8) using the Port-Access system. Intraoperative transesophageal echocardiography (TEE) was used in these patients to: (i) reassess valve pathology preoperatively; (ii) guide and continuously assess placement and position of the aortic endoclamp; (iii) measure aortic root diameters, aortic distensibility and aortic wall appearance prior to and after aortic endoclamping; (iv) evaluate the de-airing procedure; (v) evaluate the results of mitral valve repair; and (vi) guide weaning from cardiopulmonary bypass (CPB). METHODS AND RESULTS: Placement and positioning of the endoclamp was guided effectively in all but one patient who had acute retrograde aortic dissection with the onset of femoro-femoral bypass. The mean position of the tip of the endoclamp was 2.8 +/- 0.5 cm from the aortic valve annulus. The position was stable in all but five patients in whom repositioning and additional clamp volume were required. There was only a poor relationship between balloon volume and sinotubular junction diameter. The dynamic movement of the aorta was well preserved after clamping and the elasticity module did not change significantly (1.6 +/- 0.71 vs. 1.5 +/- 0.75 dynes x 10(6)/cm2). No intimal tears or wall edema was observed after clamp release. De-airing was incomplete in five patients, two of whom had transient ST-elevations with regional wall motion abnormalities. Weaning of CPB was therefore postponed until the ECG had normalized. All mitral valve repairs but one were successful (equal to or less than grade I residual mitral insufficiency). One patient with persistent grade II mitral insufficiency underwent valve replacement using the same approach. CONCLUSIONS: TEE can effectively guide minimally invasive mitral valve surgery using the Port-Access system. Placement and positioning of the endoclamp and its effects on the aortic wall can be evaluated. De-airing, weaning from CPB and the results of the procedure were effectively monitored using TEE.
Aorta↗
Pulmonary capillary pressure measurement from pulmonary artery occlusion pressure decay profile analysis in sheep.
Pulmonary capillary pressure (Ppc), the major factor responsible for pulmonary edema, cannot be directly measured in intact subjects but may be estimated by analysis of the pressure decay profile after pulmonary artery catheter balloon inflation. We compared three different methods of pulmonary artery occlusion pressure (Ppao) decay profile analysis to estimates of Ppc derived from lymph flow measurements in halothane-anesthesized sheep. The relationship between Ppc and lymph flow was first determined by increasing Ppc by left atrial balloon inflation, and was then used to determine Ppc during pulmonary hypertension produced by infusion of a thromboxane analog. All three methods of Ppao decay profile analysis demonstrated a correlation with Ppc estimated from lymph flow. However, the method using a single exponential analysis significantly overestimated Ppc, and none of the methods reliably estimated changes in the longitudinal distribution of pulmonary vascular resistance during pulmonary hypertension. These results suggest that Ppao decay profile analysis as currently performed has limited application.
15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
Physiology of the transplanted heart.
The success of cardiac transplantation has allowed for the development of a growing body of evidence regarding the function of the denervated heart, as well as provided insight into the function of the normally innervated heart. An appreciation of the basic physiology and pathophysiology of the denervated, transplanted human heart allows for a rational approach to the perioperative management of cardiac allograft recipients. Understanding the importance of preload, the alteration in the control of heart rate, the altered response to exercise, and potential for coronary artery disease, diastolic dysfunction, and chronic hypertension should assist clinicians in the care of these patients.
Catecholamines↗