Pulmonary abnormalities after coronary arterial bypass grafting operation: cardiopulmonary bypass versus mechanical stabilization.

BACKGROUND: Cardiopulmonary bypass has been implicated in causing poor pulmonary gas exchange postoperatively in patients undergoing coronary artery bypass grafting procedures. This randomized prospective study was conducted to determine whether patients undergoing coronary artery bypass grafting operations using cardiac stabilization and thereby avoiding cardiopulmonary bypass will have improved pulmonary function postoperatively. METHODS: Fifty-eight patients were randomized to one of two groups: coronary artery bypass grafting operation with stabilization or coronary artery bypass grafting operation with cardiopulmonary bypass. Preoperative and postoperative pulmonary gas exchange measurements were performed on intubated patients, including the arterial partial pressure of oxygen on 100% inspired oxygen, the alveolar-arterial oxygen gradient, and pulmonary shunt. Static and dynamic lung compliance measurements were performed postoperatively. Hemodynamic variables (including creatine kinase-MB and troponin levels), intubation time, postoperative bleeding, and blood transfusions were compared. RESULTS: Both study groups had a large decrease in arterial partial pressure of oxygen on 100% inspired oxygen (p < 0.0001) and a significant postoperative increase in the alveolar-arterial oxygen gradient (p < 0.0001). There was no statistical difference in the postoperative gas exchange between the two groups; however, the postoperative pulmonary shunt was significantly better in the stabilization group (24% versus 31%, p = 0.03). The patients were extubated in the intensive care unit earlier in the stabilization group (8.2 hours versus 9.2 hours, not significant). The mean static and dynamic lung compliance postoperatively was lower in the stabilization group, although not statistically significant (p = 0.06). CONCLUSIONS: Coronary artery bypass grafting operation using cardiac stabilization technique is safe and avoids the risk of cardiopulmonary bypass. The pulmonary gas exchange postoperatively is comparable to standard cardiopulmonary bypass procedures, but a reduced postoperative pulmonary shunt was seen in the stabilization group.

Aortic valve replacement with the freestyle stentless bioprosthesis: five-year experience.

BACKGROUND: Stentless aortic valves were designed to provide a more physiological flow pattern and lower transvalvular gradient, which may have an important bearing on postoperative left ventricular function and remodeling. In this study, we prospectively analyzed the 5-year clinical results with the Freestyle valve (Medtronic, Inc) and its hemodynamic performance by serial echocardiography. METHODS AND RESULTS: Between January 1993 and August 1997, 95 patients with a mean age of 75 years underwent aortic valve replacement with the Freestyle prosthesis. Sixty-four percent of patients received valves

Randomized trial of partial versus complete chordal preservation methods of mitral valve replacement: A preliminary report.

BACKGROUND: The merits of retaining the subvalvular apparatus during mitral valve replacement for chronic mitral regurgitation have been demonstrated in numerous clinical and laboratory investigations. In this preliminary report, we analyzed the early effects of complete versus partial chordal preservation on left ventricular mechanics. METHODS AND RESULTS: Fifty patients undergoing isolated surgical correction of mitral insufficiency were prospectively randomized to either total or partial chordal-sparing mitral valve replacement. Of the first 19 patients studied, 8 had preservation of the posterior leaflet only, and 11 had complete preservation of all chordal structures. A comparison group consisted of 6 patients who had primary mitral valve repair. Echocardiography was performed preoperatively and at discharge from the hospital to determine dimensions, wall stress, and ejection fraction. Preservation of the posterior leaflet only resulted in a reduction in end-diastolic volume, an increase in end-systolic volume (P=0.058), a rising trend in end-systolic stress, a decrease in long-axis fractional shortening, and a fall in ejection fraction from 0.68+/-0.16 to 0. 46+/-0.19 (P=0.001). Although patients who had preservation of all chordal structures also had decreased end-diastolic volume, long-axis fractional shortening, and ejection fraction (0.60+/-0.13 to 0.52+/-0.07, P=0.01), end-systolic stress fell and end-systolic volume decreased instead of increased. Compared with the posterior leaflet preservation group, those in the group with completely preserved chordal structures had a larger decline in end-diastolic volume and smaller decreases in long-axis fractional shortening and ejection fraction. Changes in end-systolic volume and stress were also statistically different between the 2 cohorts. No differences were detected between the group with total preserved chordal structures and the mitral repair group in any of the measured parameters. CONCLUSIONS: Compared with posterior chordal preservation only, complete retention of the subvalvular apparatus during mitral valve replacement resulted in improved ejection performance and smaller chamber volumes due to reduced systolic wall stress. These hemodynamic advantages are comparable to those observed with primary mitral reconstruction.

Time related quality of life after elective cardiac operation.

BACKGROUND: Due to improved operative techniques, myocardial preservation, and perioperative care, open heart procedures are now being performed in older and sicker patients. As a result, the quality of life has become an important issue in the decision making process. METHODS: Between January 1993 and October 1994, 604 patients above 65 years of age who underwent non-emergent open heart operations were followed prospectively over a 2-year period. The Health Status Questionnaire forms were distributed to all patients preoperatively and to hospital survivors at 3, 12, and 24 months. The questionnaire contains 36 questions and is divided into eight categories. Follow-up was 100% complete with 99.6% of questionnaires returned. RESULTS: Significant quality of life improvements were noted in all categories after surgery. After reaching a peak at 12 months, there were small, but significant declines in scores relating to physical health and health perception at 24 months. In contrast, measurements for mental attributes continued to increase with time. By multivariate analysis, diabetes, older age, and female gender had a relatively adverse influence on quality of life despite improvement after operation. Similarly, patients with chronic obstructive pulmonary disease or having redo operations had lower health perception with some physical limitations. While procedure type (coronary artery bypass grafting) was associated with preoperative bodily pain, congestive heart failure symptoms were not an independent factor affecting quality of life. CONCLUSIONS: Quality of life improves with cardiac surgical interventions in this studied age group and should not be denied even in the elderly population.

Aortic valve replacement with Medtronic Freestyle bioprosthesis: 5-year results.

The Medtronic Freestyle aortic root bioprosthesis has been implanted in patients since August 1992. This study reviews clinical and echocardiographic results at midterm (5 years) after implantation. The Freestyle bioprosthesis was implanted in 1,100 patients in a 21-center Food and Drug Administration clinical trial from August 1992 to October 1998. The device was implanted (1) as a subcoronary valve replacement, (2) as a complete aortic root replacement (full-root), or (3) as a root inclusion. Patients were followed annually by clinical examination and echocardiography. There were 47 deaths early after operation (7.1%). There were 2,478 patient-years of follow-up during which there were 99 deaths or 4.0/pt.-yr. Before implantation, 73% of patients were in New York Heart Association functional class III or IV. After operation, 95% were in class I or II. Transvalvular gradient 4 years after operation was low (7.5+/-5.3 mm Hg) for all valve sizes (subcoronary implant). Small valves (19 and 21 mm) had mean gradients (10.2+/-3.0, 9.1+/-4.4 mm Hg). There was no or mild valve insufficiency in 98% of patients. Actuarial analysis at 5 years showed the rate for freedom from thromboembolism of 86% in subcoronary implant and 93% in full root replacement. Freedom from endocarditis was 98%. Freedom from reoperation for explant of the valve highest in patients having full root replacement (98%) and lower with root inclusion (94%). There were 20 bioprostheses explanted; 10 for endocarditis, 8 for technical reasons, and 2 for structural deterioration. The Medtronic Freestyle bioprosthesis (1) has excellent hemodynamic performance, (2) techniques for insertion that result in a competent valve, (3) low rates of thromboembolism and endocarditis, and (4) a rare rate of structural deterioration at 5 years.

Prosthesis-patient mismatch: hemodynamic comparison of stented and stentless aortic valves.

Several centers have reported excellent clinical performance of stentless aortic xenografts. This study reports a hemodynamic comparison of the Medtronic Freestyle stentless and Mosaic stented valves. The prosthetic hemodynamics at discharge and 1 year after insertion in 95 patients who underwent aortic valve replacement with the Freestyle stentless bioprosthesis at Southern California Kaiser Permanente Medical Center were compared retrospectively with 115 unmatched individuals who received the Mosaic stented valve at the University of British Columbia. As assessed by echocardiography, there were no differences in the mean transvalvular gradient, effective orifice area (EOA), or EOA indexed to body surface area (EOAI) at discharge between the two groups. However, after 1 year, all corresponding Freestyle valve sizes had larger EOAs and lower gradients. Furthermore, fewer patients receiving Freestyle xenografts had prosthesis-patient mismatch (19% vs. 64%, P<.001) as defined by EOAI <0.85 cm2/m2. Although the Mosaic stented valve provides comparable immediate hemodynamic performance after implantation, there is significant improvement with the Freestyle bioprosthesis in terms of gradient, EOA, and prosthetic-patient mismatch at 1 year.

Freestyle valve experience: technical considerations and mid-term results.

BACKGROUND: Many studies have demonstrated the superior hemodynamics of stentless porcine aortic valves compared to stented valves. This article describes the operative techniques and reviews our 5-year experience with the Medtronic Freestyle stentless valve. METHODS: Between January 1993 and November 1997, 95 patients underwent implantation of the Medtronic Freestyle valve at a mean age of 76 years. All patients were seen at 6 months, 1 year, and annually thereafter for clinical assessment and Doppler echocardiography. RESULTS: There were three operative and ten late deaths (two cardiac and eight noncardiac). Three strokes and four transient ischemic attacks occurred in the follow-up period. Four patients had bacteremia that was treated successfully with antibiotics. No patient required reoperation for valve-related problems. Serial echocardiograms revealed a decrease in mean systolic gradients across the valve during the first year and an increase in effective orifice areas. Ninety-one percent of patients had no, or trace, aortic insufficiency at the time of discharge and this has not increased over time. CONCLUSION: The Medtronic Freestyle valve has excellent hemodynamics and good clinical results. In our experience, no patient has required reoperation in a 5-year follow-up.

Small aortic root in the elderly: use of stentless bioprosthesis.

BACKGROUND AND AIMS OF THE STUDY: Aortic root enlargement in the elderly patient prolongs aortic valve replacement procedures and may be problematic if the root is calcified. Mechanical valves have superior hemodynamics compared to tissue valves in the smaller sizes but are often contraindicated in the older patient. MATERIALS AND METHODS: Between January 1993 and November 1995, we implanted 80 Freestyle (Medtronic, Irvine, CA) stentless porcine valves using the freehand subcoronary technique. Twenty-seven of the patients had small aortic roots with an average age of 76.3 years (69-84). Seven patients received size 19 valves and 20 patients had size 21 valves. RESULTS: The average echocardiographic gradient at hospital discharge was 17.9 mmHg (12.1-23.0) for size 19 valves and 15.3 mmHg (5.7-27.9) for size 21. At one year postoperative follow up the average gradient had decreased to 12.9 mmHg (9.3-17.5) for size 19 and 8.0 mmHg (2.2-19.3) for size 21 valves. Effective orifice areas increased from 1.09 cm2 at the time of discharge to 1.29 cm2 at one year follow up for size 19 valves, and from 1.30 cm2 to 1.56 cm2 for size 21. No patient had more than mild aortic insufficiency at most recent follow up. CONCLUSION: This stentless porcine prosthesis has excellent hemodynamics in the smaller valve sizes which improve at least during the first year following surgery. We feel that it is the valve of choice in older patients with small aortic roots.

Use of extended polytetrafluoroethylene (ePTFE) chordae to re-establish annular-papillary connection after mitral valve excision.

Preserving mitral annular-papillary muscle continuity during mitral valve replacement improves left ventricular function and may help prevent ventricular rupture. In patients with severe rheumatic or myxomatous mitral valve involvement, retaining native chordae may not be possible. We describe a technique to recreate the papillary muscle-mitral annular continuity with ePTFE sutures when excision of a portion or all of the subvalvular apparatus is required.

Intraoperative autotransfusion reduces blood loss after cardiopulmonary bypass.

BACKGROUND: A combination of several techniques is necessary to minimize the transfusion requirements for open heart operations. The benefit of plasmapheresis remains in doubt because of smaller and less effective platelets obtained with this technique. Therefore, we evaluated the effects of whole blood intraoperative autotransfusion as part of a blood conservation protocol. METHODS: One hundred patients undergoing coronary artery bypass graft operations were randomized to an autotransfusion group (group A) or control group (group C). Group A patients had a 10 mL/kg of whole blood removed before cardiopulmonary bypass; they had retransfusion at the termination of cardiopulmonary bypass and heparin reversal. Both groups had intraoperative cell saving and autotransfusion of shed mediastinal blood postoperatively. The indications for blood transfusion were standardized, and the physicians ordering blood products were blinded to the study. RESULTS: Compared with the control group, patients in the autotransfusion group had a 28% reduction of chest tube drainage at 8 hours and a 45% reduction in the total homologous blood units transfused. CONCLUSIONS: Autotransfusion during cardiopulmonary bypass provides benefit in addition to other techniques in reducing blood loss and the need for blood products in the postoperative period.

Preservation of normal left ventricular geometry during mitral valve replacement.

The role of the subvalvular apparatus in preserving left ventricular (LV) systolic function, regional LV mechanics and three-dimensional contraction synergy has now been generally accepted. We have developed techniques for maintaining the mitral annulopapillary muscle continuity during mitral valve replacement (MVR) to preserve the normal geometry of the left ventricle. From January 1990 through February 1995, a total of 375 patients underwent MVR. In 183 patients, the entire subvalvular apparatus was retained or the mitral annulo-papillary muscle continuity was reconstructed with Gore-tex sutures. There were 100 males and the average patient age was 64 (24-84) years. One hundred and forty-seven patients had mechanical bileaflet valves implanted and the remaining 36 received bioprostheses. One hundred and nine patients underwent isolated MVR with an operative mortality of three (2.8%), 52 patients had combined MVR and coronary surgery with four deaths (7.7%), 15 patients had multiple valve procedures with one death (6.7%) and seven patients had MVR combined with miscellaneous procedures with no operative deaths. All patients underwent transesophageal echocardiography evaluation intra-operatively. In addition, transthoracic echocardiograms performed during the follow up period (3 mo.-5 yrs.) have demonstrated preservation of global LV function with no evidence of LV outflow tract obstruction. We conclude that preserving the LV geometry by normal anatomical chordal preservation or replacement during MVR is a safe technique resulting in gratifying intermediate term results.

Stentless porcine aortic root: valve of choice for the elderly patient with small aortic root?

The Medtronic Freestyle bioprosthesis is a stentless porcine aortic root cross-linked in dilute glutaraldehyde solution with stress-free fixation for the valve leaflets. It has been treated by a process in which amino oleic acid is used to reduce the potential for calcification. As a complete aortic root, it has the same versatility as the aortic homograft but has the advantage that it is readily available in all sizes to the implanting surgeon. Between January 1993 and May 1994, we implanted 64 Freestyle bioprostheses as aortic valve replacements using a freehand technique; 5 size 19 mm, 15 size 21 mm, 16 size 23 mm, 13 size 25 mm, and 15 size 27 mm valves were used. There were 35 men and the mean age was 75.7 years (64 to 84 years). The operative mortality was 3.1% (2/64). Echocardiograms at the time of discharge revealed mean aortic valve gradients ranging from 18.2 mm Hg for 19 mm to 10.3 mm Hg for 27 mm valves. Effective orifice areas ranged from 1.0 cm2 for 19 mm to 2.0 cm2 for 27 mm valves. No patient had more than trace aortic insufficiency. Our early experience with this new stentless bioprosthesis shows it to have excellent hemodynamics especially in the smaller valve sizes. Using this valve in patients who have a small aortic root and require a tissue valve avoids the need for aortic root enlargement procedures.

Gastrointestinal complications associated with cardiopulmonary bypass procedures.

Gastrointestinal complications after cardiopulmonary bypass (CPB) procedures are rare, but when they do occur, they carry a significant incidence of morbidity and mortality. Over a 5-year period spanning 1988-1992, 4923 CPB procedures were performed and 64 patients were identified who suffered a GI complication, giving an incidence of 1.3 per cent. The most frequent complications were GI bleeding (40%) and pancreatitis (34%). Other complications included acute cholecystitis (11%), perforated duodenal ulcer (8%), ischemic bowel (5%), and diverticulitis (2%). Complications occurred most frequently in patients undergoing procedures with longer pump and cross-clamp times, such as valvular and combination (CABG/valve) procedures. Redo procedures and the use of an intra-aortic balloon pump increased the risk of developing a GI complication 2.5 and 12 times, respectively. Patients were treated aggressively both medically and surgically, but suffered a higher mortality (16%) as compared to those not suffering a GI complication (3%). We conclude that GI complications after CPB procedures are infrequent but lethal. Clinical features are often subtle, and a high index of suspicion is needed for early diagnosis and aggressive treatment.

Surgical revascularization after acute myocardial infarction. Does timing make a difference?

At present no consensus exists regarding the timing of surgical revascularization after acute myocardial infarction. Patients admitted with acute myocardial infarction between January 1990 and April 1993 underwent early cardiac catheterization if they had postinfarction ischemia or positive results on a low-level exercise stress test. If indications for surgical intervention were found at the time of catheterization, patients were operated on within 1 or 2 days or were discharged and returned for the operation within 2 to 3 weeks. During this period, we performed 2175 isolated coronary artery bypass graft procedures; 23 patients were operated on within 24 hours of acute myocardial infarction with an operative mortality of 4.4%, 30 patients underwent surgery between 24 and 72 hours after infarction with no deaths, 193 patients were operated on between 3 and 7 days after infarction with an operative mortality of 2.1%, 284 patients underwent revascularization between 1 week and 1 month after infarction with an operative mortality of 1.4%, and the 1645 patients without a recent infarction had a mortality rate of 1.9%. Multivariate statistical analysis was performed to evaluate mortality with these independent variables: reoperative surgery, sex, age, diabetes, timing of infarction, location of infarction, and type (transmural versus subendocardial). Myocardial infarction at any time interval less than 1 month before the operation was not associated with mortality when adjusted by these other risk factors. In addition, no differences were noted in length of stay, stroke rate, or prevalence of renal failure or pulmonary insufficiency. We conclude that nonemergency surgical revascularization can be done safely at any time interval after acute myocardial infarction, certainly after 72 hours, with no increase in operative mortality and acceptable morbidity.

Transatrial approach revisited.

A surgical approach is described to provide excellent exposure of the interior of the left atrium and the mitral valve apparatus.