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Biomedical subjects

R C Daly

Publications and source records attributed to R C Daly.

At least 37 records · Page 2Linked to original sources
PubMed1999

Coronary artery bypass grafting in patients with previous mediastinal radiation therapy.

OBJECTIVES: Our objectives were to characterize the outcome of coronary artery bypass grafting in patients with previous mediastinal radiation therapy and to identify special features of this condition that relate to surgical management. PATIENTS AND METHODS: We conducted a retrospective review of 47 patients (28 women, 19 men) with a mean age of 63.5 +/- 12.8 years (range 31.0-82. 9 years) from 1976 through December 1996 undergoing coronary artery bypass graft after mediastinal radiation therapy. RESULTS: The mean interval between mediastinal radiation therapy and coronary artery bypass grafting was 15.1 +/- 9.8 years (range 1.1-37.8 years). In the 44 patients with isolated coronary surgery, operative mortality was 3 patients (6.8%). Sternal wound infection occurred in 3 patients (6.8%). Actuarial survival at 1 and 5 years was 87.2% +/- 4. 9% and 71.6% +/- 7.1%, respectively. Total follow-up was 293.7 patient-years (mean 6.2 +/- 5.1 years). There were 17 late deaths (malignancy, n = 7; heart failure, n = 6; stroke, n = 1; other noncardiac causes, n = 2; and sudden death, n = 1). Twelve of 43 discharged patients had the development of valvular disease demonstrated by follow-up echocardiography. CONCLUSIONS: The early results of coronary artery bypass grafting for the treatment of ischemic heart disease after mediastinal radiation therapy are good. Late survival, however, is limited by malignancy, either recurrent or new, and the development of heart failure. Inasmuch as 25 other patients after radiation therapy required concomitant valve surgery and 12 of 43 (28%) discharged patients had later development of valvular disease, with 2 requiring reoperation, careful assessment of any valvular lesion is important during the initial coronary artery bypass grafting. Careful follow-up, including regular echocardiographic screening, is recommended in this patient population.

Adult↗
PubMed1999

Congenitally bicuspid aortic valves: a surgical pathology study of 542 cases (1991 through 1996) and a literature review of 2,715 additional cases.

OBJECTIVE: To describe a clinicopathologic study of a large group of congenitally bicuspid aortic valves surgically excised at a single institution. MATERIAL AND METHODS: The medical charts and bicuspid valves from patients undergoing aortic valve replacement at Mayo Clinic Rochester between 1991 and 1996 were retrospectively reviewed. RESULTS: The age of the 542 patients ranged from 1 to 86 years (mean, 61), and 372 (69%) were men. Among these, 409 (75%) had pure aortic stenosis (AS), 73 (13%) had pure aortic insufficiency (regurgitation) (AI), 53 (10%) had combined AS and AI, and 7 (1%) had normal function. The mean age was higher for those with AS than AI (65 versus 46 years; P < 0.001), whereas the male-to-female ratio was higher for AI than AS (17.3:1 versus 1.7:1; P < 0.001). The two cusps were not equal in size in 95%, and a raphe was present in 76% (67% typical, 9% atypical). Raphal position was described in 315 and was between the right and left cusps in 270 (86%). Raphal absence occurred more often in valves with equal-sized cusps than unequal (33% versus 14%; P = 0.005). Moderate to severe calcification affected valves with AS more frequently than AI (99% versus 41%; P < 0.001). In contrast, annular dilatation was associated with AI more than AS (48% versus 11%; P < 0.001). Acquired commissural fusion involved valves with combined AS and AI more often than the other functional states (31% versus 14%; P = 0.002). Sixteen patients (age range, 18 to 78 years; 13 men) had infective endocarditis (6 active, 10 healed), including 10 with AI (9 men), 3 with AS plus AI, 2 with AS, and 1 with normal function but embolization. CONCLUSION: Functionally, the most common fate of congenitally bicuspid aortic valves was calcific stenosis with or without regurgitation (85%). Because approximately 4 million US citizens have bicuspid valves and because valve replacement is currently the only treatment of symptomatic AS, this disorder will continue to affect health-care costs.

Adolescent↗
PubMed1999

Cerebral response to hemodilution during hypothermic cardiopulmonary bypass in adults.

UNLABELLED: We examined the cerebral response to changing hematocrit during hypothermic cardiopulmonary bypass (CPB) in 18 adults. Cerebral blood flow (CBF), cerebral metabolic rate for oxygen (CMRO2), and cerebral oxygen delivery (CDO2) were determined using the nitrous oxide saturation technique. Measurements were obtained before CPB at 36 degrees C, and twice during 27 degrees C CPB: first with a hemoglobin (Hgb) of 6.2 +/- 1.2 g/dL and then with a Hgb of 8.5 +/- 1.2 g/dL. During hypothermia, appropriate reductions in CMRO2 were demonstrated, but hemodilution-associated increases in CBF offset the reduction in CBF seen with hypothermia. At 27 degrees C CPB, as the Hgb concentration was increased from 6.2 to 8.5 g/ dL, CBF decreased. CDO2 and CMRO2 were no different whether the Hgb was 6.2 or 8.5 g/dL. In eight patients in whom the Hgb was less than 6 g/dL, CDO2 remained more than twice CMRO2. IMPLICATIONS: This study suggests that cerebral oxygen balance during cardiopulmonary bypass is well maintained at more pronounced levels of hemodilution than are typically practiced, because changes in cerebral blood flow compensate for changes in hemoglobin concentration.

Aged↗
PubMed1998

New approaches to prevention and treatment of radial artery graft vasospasm.

BACKGROUND: There has been renewed interest in radial artery (RA) conduits for coronary artery bypass because of the relative resistance of arterial grafts to atherosclerosis compared with autogenous vein grafts. Although improved drug therapy for arterial spasm is now available, vasospasm still occurs in at least 5% to 10% of RA grafts. We systematically evaluated the effectiveness of calcium channel blockers and organic nitrates for inhibition or reversal of RA contraction in vitro. Additionally, we investigated the efficacy of novel gene therapy with endothelial nitric oxide synthase (eNOS) to inhibit RA contractions. METHODS AND RESULTS: Segments of RA from 28 patients undergoing coronary artery bypass grafting were mounted in organ chambers. In control experiments, KCl (5 to 50 mmol/L) produced dose-dependent increases in tension (maximum tension, 14.3 +/- 3.0 g, n = 7). Addition of diltiazem or verapamil had no significant effect on KCl contraction (128 +/- 36% and 88 +/- 24% control, respectively); however, nifedipine markedly inhibited KCl contraction (27 +/- 4% control, P = 0.005). Norepinephrine (NE, 10(-9) to 10(-4) M) produced dose-dependent increases in tension (maximum tension, 15.7 +/- 2.7 g in control rings, n = 8). Diltiazem and verapamil pretreatment had no significant effect on NE contraction (103 +/- 14% and 90 +/- 14% control, respectively); nifedipine significantly inhibited NE contraction (70 +/- 11% control, P = 0.02). Isosorbide dinitrate and nitroglycerin markedly inhibited KCl contractions (47 +/- 9% and 30 +/- 8% of controls, n = 6) and NE contractions (42 +/- 10% and 31 +/- 9% of controls, n = 6). Nifedipine, isosorbide, and nitroglycerin were further evaluated for the ability to reverse an established contraction (KCl 40 mmol/L); nitroglycerin was most effective in reversing RA contraction. In separate experiments, RA underwent adenoviral-mediated gene transfer with vehicle, Escherichia coli beta-galactosidase, or eNOS (eNOS, 10(10) PFU/mL x 1 hour). Transgene expression was confirmed by beta-galactosidase activity and eNOS immunohistochemistry after 40 hours of ex vivo incubation. Immunohistochemistry demonstrated recombinant NOS in adenovirus encoding bovine eNOS (Ad.CMVeNOS) RA only. Ad.CMVeNOS arteries contracted only 46.6 +/- 13.7% of controls to KCl (n = 5) and 48.2 +/- 11.4% of controls to prostaglandin F2 alpha a (10(-9) to 10(-6) M, n = 5). CONCLUSIONS: Diltiazem, which is used empirically to prevent RA vasospasm, had little effect on human RA contractions (receptor-independent and receptor-dependent). Organic nitrates inhibited and reversed RA contractions. Adenoviral transfer of NOS suggests that future clinical application of gene therapy may play an important role in prevention of RA vasospasm.

Adenoviridae↗
PubMed1998

Minimum hematocrit at differing cardiopulmonary bypass temperatures in dogs.

BACKGROUND: The purpose of this study was to determine the minimum hematocrit (Hct) supporting cerebral oxygenation over the range clinically relevant cardiopulmonary bypass (CPB) temperatures in dogs. The effect of hemodilution on cerebral blood flow (CBF), cerebral metabolic rate (CMRO2), and cerebral oxygen delivery (CDO2) was determined over a range of Hcts during CPB at 38 degrees C, 28 degrees C, and 18 degrees C. METHODS AND RESULTS: Measurements were obtained at target CPB temperature and after progressive normovolemic hemodilution in 3 groups of 8 anesthetized animals. Dextran 70 (6%) was used as a diluent. CBF was measured by use of the sagittal sinus outflow technique. CMRO2 and CDO2 were calculated by the use of standard formulae. In each temperature group, hemodilution was associated with a reciprocal rise in CBF. As Hct was reduced to 0.10 +/- 0.02 at 38 degrees C, 28 degrees C, and 18 degrees C, CBF increased 260%, 220%, and 160% of the control nonhemodiluted value. Increases in CBF helped compensate for decreased arterial oxygen content and maintain CDO2. With progressive temperature reduction, these compensatory flow increases were reduced and CDO2 was decreased at lesser degrees of hemodilution. Statistical analysis indicated that cerebral oxygen demand was maintained to an Hct of 0.14, 0.11, and < or = 0.10 in the 38 degrees C, 28 degrees C, and 18 degrees C groups; however, physiologically important changes in cerebral oxygen supply occur at Hcts of approximately 0.18, 0.15, and 0.12, respectively, at those temperatures. CONCLUSIONS: This investigation systematically characterizes the critical Hct supporting cerebral oxygenation at differing CPB temperatures. Over a range of CPB temperatures, the curve describing the relationship between Hct and cerebral oxygen balance has a broad plateau, indicating cerebral tolerance for a wide range of Hcts. The minimum Hct that supports cerebral oxygenation is shifted leftward as temperature is reduced, but the reduction in critical Hct is not proportional to the reduction in CMRO2. Although we do not advocate hemodilution to these extreme values, we find that these data provide a physiological foundation for our hemodilution practice and provide some guidance for management of Hct as body temperature changes during CPB.

Animals↗
PubMed1998

Minimally invasive saphenous vein harvesting: endothelial integrity and early clinical results.

BACKGROUND: Endoscopic harvesting of vein grafts may reduce wound complications but the effect on the venous endothelium is unknown. Endothelium-derived vasoactive substances may be important in vein graft disease prevention. We investigated the impact of endoscopic harvesting on the release of these factors and proceeded to evaluate the clinical applicability. METHODS AND RESULTS: Porcine veins were harvested in either an endoscopic or open fashion. Superfusion bioassay from endoscopic veins had a similar basal secretion as control veins (6.5% +/- 1.5% versus 3.2% +/- 2.2%, respectively; n = 5, p = 0.39). Calcium ionophore A23187 stimulation was similar in both groups (24.6% +/- 5.1% versus 27.3% +/- 9.6%; n = 5, p = 0.68). Light and electron microscopy documented a normal endothelial monolayer in both groups with no endothelial cell or connective tissue loss. Encouraged by these results, 38 patients have subsequently undergone this procedure at our institution. Total operative time for harvesting 35 to 45 cm of saphenous vein was 62.3 +/- 5.3 minutes (range, 35 to 120 minutes). The procurement time in the most recent five patients was 41.6 +/- 3.3 minutes. Patients had little incisional pain, but did have mild ecchymosis. CONCLUSIONS: Endothelial release of vasoactive substances after endoscopic harvesting is similar to that after the traditional, extended incision technique, and microscopy confirmed similar histology. These laboratory findings support the satisfactory early clinical experience with endoscopic harvesting of saphenous veins.

Adult↗
PubMed1998

Critical cerebral perfusion pressure during tepid heart operations in dogs.

BACKGROUND: The management of blood pressure during cardiopulmonary bypass varies widely. This may be particularly relevant with the trend to warmer bypass temperatures and an older patient population. Therefore, we examined the minimal perfusion pressure that maintains cerebral oxygen delivery during cardiopulmonary bypass at 33 degrees C. METHODS: Ten dogs were placed on bypass and body temperature was reduced to 33 degrees C (alpha-stat pH management). At six randomly ordered mean arterial blood pressures (35, 40, 45, 50, 60, and 70 mm Hg), cerebral blood flow, oxygen delivery, and metabolic rate were determined. RESULTS: Cerebral oxygen delivery was stable if the mean arterial pressure was greater than or equal to 60 mm Hg. If mean arterial pressure was less than or equal to 50 mm Hg, cerebral oxygen delivery decreased, and at less than 45 mm Hg cerebral ischemia was seen. CONCLUSIONS: In a dog without vascular disease, the brain becomes perfusion pressure-dependent at a mean arterial pressure of approximately 50 mm Hg. There is no leftward shift of the cerebral autoregulatory curve during bypass at 33 degrees C. Greater support of mean arterial pressure during "tepid" cardiopulmonary bypass is indicated in the current adult surgical population that is older and has vascular comorbidity.

Animals↗
PubMed1998

Hemodilution and whole body oxygen balance during normothermic cardiopulmonary bypass in dogs.

OBJECTIVE: The purpose of this study was to determine the minimum hematocrit value that can support whole body oxygen consumption during normothermic cardiopulmonary bypass. The effect of hemodilution on peripheral resistance, whole body oxygen delivery, and oxygen consumption was determined over a range of hematocrit values. METHODS: Measurements were obtained during 38 degrees C cardiopulmonary bypass with progressive normovolemic hemodilution (hematocrit value 40% to 9%) in nine dogs. Dextran 70 (6%) was used as a diluent. Anesthesia consisted of high-dose fentanyl and midazolam. A mean arterial pressure of 60 mm Hg was maintained throughout cardiopulmonary bypass via increases in pump flow. RESULTS: Progressive hemodilution was associated with a decreasing total peripheral resistance. During normothermic cardiopulmonary bypass with a whole blood prime, the whole body oxygen consumption approximated values previously reported in dogs under nonbypass conditions. Oxygen delivery and whole body oxygen uptake were maintained between a hematocrit value of 39% and 25%. Significant decreases for both were seen when the hematocrit value was reduced to 18% and below. CONCLUSIONS: A hematocrit level greater than 18% was needed to maintain systemic oxygen delivery and consumption during warm cardiopulmonary bypass. The critical hematocrit value may be higher under bypass than nonbypass conditions because the flow increases that are practical during cardiopulmonary bypass do not approximate those seen in response to hemodilution of the intact circulation. Finally, the critical hematocrit value for the body may be higher than that required for the brain during warm cardiopulmonary bypass.

Animals↗
PubMed1998

Cardiac transplantation for end-stage congenital heart defects: the Mayo Clinic experience. Mayo Cardiothoracic Transplant Team.

OBJECTIVE: To review the outcome of cardiac transplantation undertaken in patients with congenital heart defects. MATERIAL AND METHODS: Between November 1991 and March 1998 at our institution, cardiac transplantation was performed in 16 patients with congenital heart disease (age range, 3 to 57 years; mean, 26.1). Preoperative diagnoses included univentricular heart (N = 4); complete transposition of the great arteries (N = 3); Ebstein's anomaly (N = 2); tetralogy of Fallot (N = 2); levotransposition (N = 2); dextrocardia, corrected transposition, ventricular and atrial septal defects, and pulmonary stenosis (N = 1); double-outlet right ventricle (N = 1); and hypertrophic obstructive cardiomyopathy (N = 1). All patients had undergone from one to five previous palliative operations. RESULTS: Four patients required permanent pacemaker implantation during the first month postoperatively because of bradycardia; more than 2 years later, another patient required a permanent pacemaker because of sick sinus syndrome. In addition, one patient had an automatic implantable cardioverter-defibrillator. Three patients required reconstruction of cardiovascular structures with use of prosthetic material (Teflon patches or donor tissue) at the time of cardiac transplantation. Actuarial 1-, 2-, and 5-year survival was 86.2 +/- 9.1%. During the first year after transplantation, two deaths occurred--one at 41 days of putative vascular rejection and the second at 60 days of severe cellular rejection. All other patients are alive and functionally rehabilitated; the mean follow-up period has been 26.1 months (range, 2 to 89.6). CONCLUSION: Cardiac transplantation for patients with congenital heart disease can be accomplished with a low perioperative mortality and an excellent medium-term survival despite the challenges presented by the technical difficulties during invasive diagnostic procedures and at operation and the need for adherence to long-term multiple-drug therapy in this patient population.

Actuarial Analysis↗
PubMed1997

Third and fourth operations for myocardial ischemia: short-term results and long-term survival.

BACKGROUND: An increasing number of patients having at least two operations for myocardial ischemia are now presenting for a third or fourth procedure. We report the Mayo Clinic experience with repeated reoperative surgery for coronary artery disease. METHODS AND RESULTS: We have evaluated 67 consecutive patients (54 men, 13 women) during a 14-year period (1978 to 1992). The mean age at the third procedure (n=63) was 63.4 years and at the fourth procedure (n=4) was 70.6 years. Clinical indications for surgery were unstable angina in 29 patients (43%), New York Heart Association class III angina in 36 (54%), non-Q wave acute myocardial infarction in 1, and acute pulmonary edema in 1. Urgent or emergency surgery was undertaken in 17 patients (25%). All patients had triple-vessel disease, and 20 (30%) had left main coronary artery stenosis >50%. The mean ejection fraction in 56 patients was 0.56+/-0.11. Occlusion or significant stenoses of preexisting saphenous grafts were thought to be the major cause of recurrent ischemia in 64 patients (96%). Only 14 patients (21%) had received previous arterial grafts. An average of 2.4 grafts was placed, and a new internal mammary artery was used on 47 occasions. Eight patients (11.9%) died. Three patients required a left ventricular assist device, and one of them survived. There were 21 late deaths: 8 were cardiac and 5 were likely to be cardiac. Five-year and 10-year survival in all patients was 75.6%+/-5.3% and 47.9%+/-7.7%, respectively. Freedom from further intervention for hospital survivors at 5 and 10 years was 88.4+/-4.5 and 72.3+/-8.5%, respectively. Of the 38 patients still alive at last follow-up, 29 (76%) were considered to be in New York Heart Association functional class I or II. On univariate analysis, use of an intra-aortic balloon pump, prolonged bypass time, left main coronary artery stenosis >50%, and a surgeon's impression of angiographic inoperability correlated with increased risk of early mortality. CONCLUSION: We conclude that in a select group of patients, repeated reoperative surgery, despite an increased mortality, can result in good long-term survival and significant improvement in clinical status.

Aged↗
PubMed1997

Minimum hematocrit for normothermic cardiopulmonary bypass in dogs.

BACKGROUND: The purpose of this study was to determine the minimum hematocrit supporting cerebral oxygenation during normothermic cardiopulmonary bypass (CPB) in dogs. The effect of hemodilution on cerebral blood flow (CBF), cerebral metabolic rate (CMRO2), and cerebral oxygen delivery (CDO2) was determined over a range of hematocrits. METHODS AND RESULTS: Measurements were obtained during 37.5 degrees C CPB with progressive normovolemic hemodilution (hematocrit 0.39 to 0.9) in eight anesthetized animals. Dextran 70 (6%) was used as a diluent. CBF was measured using the sagittal sinus outflow technique. CMRO2 and CDO2 were calculated using standard formula. Hemodilution was associated with a reciprocal rise in CBF. CBF at a hematocrit of 0.09 was 240% of the CBF when the hematocrit was 0.39. Increases in CBF compensated for decreased arterial oxygen content and CDO2 was maintained to a mean hematocrit of 0.14+/-0.02. At a hematocrit of 0.09+/-0.02, CDO2 and CMRO2 declined. Intracranial pressure remained stable throughout. Thus, the critical hematocrit for brain (the hematocrit at which metabolism becomes delivery-dependent) was between 0.09 and 0.14 during normothermic CPB in dogs. CONCLUSIONS: This is the first systematic attempt to determine the critical hematocrit supporting cerebral oxygenation during warm CPB. The curve describing the relationship between hematocrit and cerebral oxygen balance has a broad plateau and a genu near a hematocrit value of 0.15. While we do not advocate hemodilution to a hematocrit of 15% during "warm" CPB, these data provide a physiological foundation for our hemodilution practice and offer an explanation why low hematocrits are tolerated in certain patient populations.

Animals↗
PubMed1997

Effects of pentoxifylline on renal function and blood pressure in cardiac transplant recipients: a randomized trial.

BACKGROUND: The current success of cardiac transplantation is in part attributable to the development of effective immunosuppressive agents such as cyclosporine. However, concern remains regarding the potential for cyclosporine-induced nephrotoxicity. Animal studies and early reports of renal protective effects of pentoxifylline in bone marrow transplant recipients prompted a randomized trial in cardiac transplant recipients. METHODS: Twenty-nine patients were randomized to receive pentoxifylline 400 mg p.o. t.i.d. or matching placebo for 1 year after cardiac transplantation. Renal function was assessed preoperatively and at 1, 6, and 12 months postoperatively. Glomerular filtration rate and renal plasma flow were measured with iothalamate and para-aminohippurate, respectively. Serum creatinine was also measured. Ambulatory blood pressure monitoring after withdrawal of antihypertensives for 3 days was performed 12 months postoperatively. RESULTS: Twenty-seven patients completed the study. Glomerular filtration rate rose between 1 and 6 months after transplantation, presumably due to the reduction in goal cyclosporine level in that period, and then fell modestly between 6 and 12 months, presumably due to ongoing nephrotoxic effects of cyclosporine. No difference in glomerular filtration rate or creatinine was seen between pentoxifylline and placebo groups at any interval. Renal plasma flow increased modestly between baseline and 6 months in the pentoxifylline group, but not in the placebo group, and then fell between 6 and 12 months. Serum creatinine increased between baseline and 6 months in both groups, apparently due to increased body weight. Results of 18-hr ambulatory blood pressure monitoring obtained 1 year after transplantation was not different between groups. CONCLUSIONS: Renal function declines only modestly in the first year after cardiac transplantation. Pentoxifylline did not attenuate this process and had no effect on blood pressure. The modest decline in renal function may be related to current immunosuppressive strategies.

Adult↗
PubMed1997

Native lung complications after single lung transplantation for emphysema.

We reviewed the impact of the presence of the native diseased contralateral lung on the outcome after single lung transplantation for emphysema. Twenty consecutive recipients of single lung transplants for emphysema were reviewed for complications related to the native lung. Five patients (25%) suffered major complications arising in the native lung and resulting in serious morbidity and mortality. The timing of onset varied from 1 day to 43 months after transplantation. We conclude that the susceptibility of the native lung to complications such as those described in this report is an additional fact to be considered in choosing the ideal transplant procedure for patients with obstructive lung disease.

Adult↗
PubMed1997

Nitrous oxide method of measuring cerebral blood flow during hypothermic cardiopulmonary bypass.

BACKGROUND: Determination of cerebral blood flow and oxygenation is a means of evaluating our cardiopulmonary bypass (CPB) practice. Because much of CPB is hypothermic, our measurement technique must be valid over a range of temperatures. In this study we evaluate the validity of N2O washin for measurement of cerebral blood flow and oxygenation at three temperatures. METHODS: Cerebral blood flow and oxygenation were measured in 7 dogs undergoing CPB at 37 degrees, 32 degrees, and 27 degrees C using simultaneous direct (sagittal sinus outflow) and indirect (nitrous oxide washin) techniques. Animals underwent CPB with a whole blood prime and alpha-stat pH management. RESULTS: In the absence of hemodilution, cerebral blood flow and oxygenation were reduced by approximately 38% and 55% at 32 degrees C and 27 degrees C, respectively, by both techniques. Direct and indirect methods showed an excellent correlation (R = 0.87) during CPB between 27.5 degrees C and 37.8 degrees C (21 paired measurements). CONCLUSIONS: This investigation demonstrates that the correlation between a direct measure of global cerebral blood flow and that obtained by the N2O saturation method is excellent during CPB over the range of common CPB temperatures.

Animals↗
PubMed1997

Hemodynamic performance of small aortic valve bioprostheses: is there a difference?

BACKGROUND: There is the potential for left ventricular outflow obstruction when small aortic valve bioprostheses are employed in normal-sized or large adults. It has been hoped that bovine pericardial valves would improve hemodynamic performance in the smaller tissue valve sizes. METHODS: To determine in vivo hemodynamic performance of heterograft aortic valve prostheses, we analyzed echocardiographic data from patients receiving 21- or 23-mm Carpentier-Edwards pericardial, Medtronic Intact, and Carpentier-Edwards porcine bioprostheses. In addition, data from 19-mm Carpentier-Edwards pericardial valves were included for comparison of hemodynamic performance between valve sizes. Doppler echocardiography was performed in 151 patients within 2 weeks of operation. Left ventricular outflow gradient was derived from continuous Doppler measurements of flow velocity, and effective orifice area was calculated by the continuity equation. RESULTS: There were statistically significant differences in hemodynamic performance of different sized prostheses for each valve type (effective orifice area, p < 0.01; valvular gradient, p < 0.03). There were, however, no significant differences in effective orifice area or mean gradient for different valve types within each size category. CONCLUSIONS: The in vivo hemodynamic performance of these three different aortic valve heterograft bioprostheses is similar. Patient-prosthesis mismatch with heterograft prostheses, as demonstrated by the indexed effective orifice area can be avoided by appropriate sizing and use of annular enlarging techniques when necessary.

Adult↗
PubMed1997

Results of allograft aortic valve replacement for complex endocarditis.

METHODS: Between November 1985 and July 1995, 36 patients underwent allograft aortic valve replacement for endocarditis. The mean age of the 29 men and seven women was 53 years (range 25 to 79 years). Previous procedures included mechanical (n = 9), bioprosthetic (n = 5), and allograft (n = 2) aortic valve replacement, aortic valvotomy (n = 1), and orthotopic heart transplantation (n = 1). Infecting organisms were Staphylococcus and Streptococcus species in 69% of patients and fungi in 6%. Intraoperative findings demonstrated valvular vegetations (n = 25), annular abscesses (n = 25), and cusp destruction (n = 13). Complex reconstruction of the aortic anulus was required in 25 patients, and associated procedures included mitral valve repair (n = 2), mitral valve replacement (n = 3), coronary artery bypass grafting (n = 8), repair of ventricular septal defect (n = 4), left ventricular aneurysmectomy (n = 1), and repair of atrial septal defect (n = 1). Allograft valve insertion was performed by the scalloped technique in seven, intraaortic cylinder technique in 19, and allograft aortic root replacement in 10. RESULTS: Follow-up was 100% complete at a mean of 2.6 +/- 2.8 years after valve replacement. Operative mortality was 13.8%. Complications included low cardiac output (n = 10), bleeding (n = 2), myocardial infarction (n = 1), stroke (n = 1), renal insufficiency (n = 2), respiratory insufficiency (n = 3), and heart block (n = 8). Late echocardiogram (mean 2.6 +/- 1.8 years) demonstrated grade III/IV aortic regurgitation in five patients. There were seven late deaths (five cardiac, not valve-related; two noncardiac). No patient has had recurrence of endocarditis. Actuarial survival at 5 years was 53.1% +/- 11.5%. Univariate analysis demonstrated prosthetic valve endocarditis to adversely affect late survival (p = 0.04). Cumulative risk of reoperation at 5 years was 8.0% +/- 5.6%. CONCLUSION: Allograft aortic valve replacement facilitated reconstruction of complex aortic valve endocarditis with a low reoperation rate and no recurrent endocarditis in this series.

Adult↗
PubMed1997

Reoperation for hemolytic, anaemia complicating mitral valve repair.

OBJECTIVE: To identify the possible cause(s) of hemolysis after mitral valve repair for mitral regurgitation (MR) and to evaluate the late outcome of surgical treatment. METHODS: We reviewed all patients who had reoperation after valve repair for mitral regurgitation. Ten patients had reoperation because of hemolytic anaemia. The diagnosis of hemolysis was made by decreased serum haptoglobin, elevation of serum lactate dehydrogenase (LDH), and schistocytosis. No other causes of anaemia or hemolysis were identified in these six men and four women (ages 35-84 years; median 59 years). Interval between initial mitral valve repair and reoperation ranged from 40 to 165 days (median 87 days), and prior to reoperation, red cell transfusions (range 2-12 units; median 5 units) were required in all patients. Seven patients were symptomatic: two complained of easy fatigability and five were severely limited. Transesophageal echocardiogram during hemolytic evaluation showed only mild MR in two patients, moderate in five, moderately severe in two and severe in one. RESULTS: Etiology of hemolysis was suggested from echocardiography and confirmed at reoperation. In one patient, an eccentric MR jet struck a pledget of a commissural annuloplasty. In the remaining nine patients, the regurgitant jet struck a non-endothelialized portion of the annuloplasty ring (Carpentier-Edwards n = 5; Duran n = 2; Cosgrove-Edwards n = 2). Seven patients had prosthetic replacement and three patients had re-repair. There were no operative deaths and all patients had resolution of hemolytic anaemia. CONCLUSIONS: Relatively minor degrees of regurgitation after mitral valve repair can produce hemolytic anaemia which is manifested within the first few postoperative months. Most patients are highly symptomatic because of anaemia. The mechanism of red cell destruction is a high velocity eccentric stream of blood impacting on a small area of a prosthetic ring or pledget. This process retards endothelialization of the ring. Reoperation with re-repair or mitral valve replacement is safe and effectively relieves the hemolysis.

Adult↗