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Biomedical subjects

B W Lytle

Publications and source records attributed to B W Lytle.

At least 37 records · Page 2Linked to original sources
PubMed2000

Competing risks after coronary bypass surgery: the influence of death on reintervention.

OBJECTIVE: For groups of patients at high risk of death, such as older patients, the actual probability of experiencing a nonfatal event, such as reintervention, must be far smaller than the potential probability were there no attrition by death. Competing risks analysis quantifies the difference. METHODS: Multivariable analyses were performed for the competing events death before reintervention, reoperation, and percutaneous transluminal coronary angioplasty in 2001 patients after bilateral internal thoracic artery grafting and in 8123 after single internal thoracic artery grafting. Follow-up was 9.7 +/- 3.0 years and 10.8 +/- 5.2 years in bilateral and single internal thoracic artery groups, respectively. RESULTS: Patients receiving single grafts experienced shorter survival and more reinterventions (P <.0001). However, other risk factors for death included old age (P <.0001), but risk factors for reintervention included young age (P <.0001). This difference confounds interpretation of event-free survival that is clarified by competing risks analysis. Death reduced the potential benefit of bilateral internal thoracic artery grafting on reintervention by angioplasty from a median of 8.5% to 5.5% at 12 years and by reoperation from 9.3% to 6.8%, with progressively greater erosion of benefit from attrition by death as age increased. Competing risks simulation confirmed that young age was a true risk factor for reintervention, excluding the explanation that it reflected simply passive attrition by death as patients age. CONCLUSIONS: Even after accounting for attrition by interim deaths, bilateral versus single internal thoracic artery grafting and older age are associated with fewer reinterventions. However, in high-risk patients, its benefit on freedom from reintervention is eroded considerably by death.

Adult↗
PubMed2000

Isolated bypass grafting of the left internal thoracic artery to the left anterior descending coronary artery: late consequences of incomplete revascularization.

OBJECTIVE: Multiple strategies to achieve some degree of myocardial revascularization are available. In some, less complete revascularization is accepted to limit invasiveness. To examine the issues of incomplete revascularization, we assessed the long-term impact of additional non-left anterior descending coronary artery stenoses in patients undergoing only grafting of the left internal thoracic artery to the left anterior descending coronary artery. METHODS: A total of 2067 patients underwent primary isolated grafting of the left internal thoracic artery to the left anterior descending coronary artery from 1971 to 1997. Of these, 26% and 13% had 2- and 3-system disease, respectively. Multivariable analyses of survival and reintervention were performed in the hazard function domain for 27,683 patient-years of follow-up (mean 14 +/- 6.7). RESULTS: Survival was 99%, 88%, and 62% at 1, 10, and 20 years. Right coronary artery or left circumflex system disease of 50% or more (P =.02) and particularly high-grade (>/=70%) left circumflex (P =.01) and proximal right coronary artery disease (P =.01), as well as any degree of left main trunk stenosis (P <.0001), were associated with reduced long-term survival. Compared with 75% 20-year survival in patients with no non-left anterior descending disease, those with either left circumflex or left main trunk disease experienced a 44% survival, and those with proximal right coronary artery disease, 42%. The most common stated reason for incomplete revascularization was small vessel size. Freedom from reintervention was 89% and 65% at 10 and 20 years, respectively. High-grade left main trunk disease, but, in contrast, mid or distal disease of the right coronary artery, and not left circumflex disease, were risk factors for reintervention. CONCLUSIONS: These findings call into question the long-term appropriateness of interventions whose strategy includes leaving unrevascularized segments in territories not in the distribution of the left anterior descending coronary artery.

Adult↗
PubMed2000

The atherosclerotic aorta at aortic valve replacement: surgical strategies and results.

BACKGROUND: Aortic valve replacement in patients with severe atherosclerosis of the ascending aorta poses technical challenges. The purpose of this study was to examine operative strategies and results of aortic valve replacement in patients with a severely atherosclerotic ascending aorta that could not be safely crossclamped. PATIENTS AND METHODS: From January 1990 to December 1998, 4983 patients had aortic valve surgery; of these, 62 (1.2%) patients had a severely atherosclerotic ascending aorta and required hypothermic circulatory arrest to facilitate aortic valve replacement. They form the study group. RESULTS: All patients had hypothermic circulatory arrest, but several different strategies were used to manage the ascending aorta. These techniques included aortic valve replacement with the use of hypothermic circulatory arrest (39%), ascending aortic endarterectomy (26%), ascending aortic replacement (19%), aortic inspection and crossclamping during hypothermic circulatory arrest (10%), and balloon occlusion of the ascending aorta (6%). Duration of hypothermic circulatory arrest was substantially longer for patients having aortic valve replacement with hypothermic circulatory arrest than for all other strategies. Hospital mortality was 14%, and 10% of patients had strokes. Increasing New York Heart Association functional class and impaired left ventricular function were risk factors for hospital mortality. Choice of operative technique did not influence patient outcome; however, no patient who underwent replacement of the ascending aorta had a stroke. CONCLUSIONS: Aortic valve replacement in patients with severe atherosclerosis of the ascending aorta is associated with increased operative morbidity and mortality. Complete aortic valve replacement during hypothermic circulatory arrest, the "no-touch" technique, requires a prolonged period of circulatory arrest. Ascending aortic replacement is a preferred technique, as it requires a short period of hypothermic circulatory arrest and results in comparable mortality with a low risk of stroke.

Adult↗
PubMed1999

Correlation of preoperative myocardial function, perfusion, and metabolism with postoperative function at rest and stress after bypass surgery in severe left ventricular dysfunction.

Previous studies of dobutamine echocardiography (DE) and positron emission tomography (PET) showed similar accuracy for predicting improvement in resting wall motion after revascularization, although limited direct comparative data are available. We sought to compare the relative accuracy of detecting contractile reserve, ischemia, perfusion, and myocardial metabolism for predicting functional recovery after coronary bypass surgery in 94 consecutive patients (aged 63+/-11 years) with chronic coronary disease and depressed left ventricular function (ejection fraction 28+/-5%). PET imaging comprised rest and dipyridamole stress myocardial perfusion images, with fluorodeoxyglucose to define metabolism-perfusion mismatch. A standard dobutamine-atropine stress was used, with evaluation of low- and peak-dose echocardiographic responses. Regional function was assessed after 13+/-16 weeks at rest in 68 patients who underwent isolated coronary bypass operation without evidence of perioperative infarction, and at rest and stress in a subgroup of 29 patients. Concordance between methods for evaluating abnormal segments (ischemic, viable, and scar) and accuracy of both tests for predicting improvement in regional function were identified. Concordance between PET and DE for identifying viable or nonviable myocardium was 63% using a 16-segment model. For predicting improved resting function after surgery, the sensitivity of PET (84%) was superior to DE (69%, p<0.001), but DE was more specific (78% vs. 37%, p<0.0001) and more accurate (75% vs. 53%, p<0.001) in predicting recovery at rest. Analysis of postoperative recovery of segmental function during stress also showed the specificity of DE to exceed that of PET (89% vs. 32%, p<0.001). The accuracy of DE was enhanced by evaluation of function during stress (86%, p<0.001), but this was not altered with PET (52%, p = NS). Thus, PET is more sensitive than DE in predicting functional recovery, but DE is more specific than PET. Evaluation of left ventricular functional recovery during stress may be preferable to assessment at rest.

Cardiotonic Agents↗
PubMed1999

Injury to a patent left internal thoracic artery graft at coronary reoperation.

BACKGROUND: The purpose of this study was to determine the prevalence, outcome, and operative strategies for patients having injury to a patent left internal thoracic artery (LITA) graft to the left anterior descending coronary artery (LAD) at coronary reoperation. METHODS: Of 655 patients with a patent LITA graft to the LAD undergoing coronary reoperation from 1986 to 1997, 35 (5.3%) sustained intraoperative injury to the LITA graft. RESULTS: Strategies to restore flow to the LAD included new saphenous vein graft to the LAD in 15 patients, saphenous vein graft to the LITA stump in 7, saphenous vein graft to the LAD and repair of the LITA graft in 6, and other strategies in 7. All or part of the LITA graft to the LAD was salvaged in 20 patients (57%). Fourteen patients (40%) sustained perioperative myocardial infarction, and 3 patients died (8.6%). The 3 patients who died all had stenosis or thrombosis of the graft to the LAD documented at autopsy. CONCLUSIONS: We conclude that (1) the prevalence of injury to a patent LITA graft is 5.3%; (2) a variety of techniques can be used to restore blood flow to the LAD; and (3) ineffective revascularization of the LAD in this situation is associated with operative mortality. At primary coronary artery bypass grafting, the LITA pedicle should be positioned in the left chest away from the posterior sternal table; this strategy may minimize the risk of LITA graft injury at coronary reoperation.

Adult↗
PubMed1999

Is anterior leaflet repair always necessary in repair of bileaflet mitral valve prolapse?

BACKGROUND: Traditionally, bileaflet prolapse has been treated by posterior leaflet resection combined with one of a number of procedures designed to support the anterior leaflet. However, most patients with bileaflet prolapse do not have important anterior chordal pathology. This study was undertaken to evaluate the effectiveness of a strategy of posterior leaflet resection and annuloplasty alone for patients with bileaflet prolapse and no anterior chordal rupture or severe anterior chordal elongation. METHODS: From 1993 to 1997, 93 patients with transesophageal echocardiography (TEE) demonstrated bileaflet prolapse and without anterior chordal rupture or important anterior chordal elongation had primary isolated mitral valve repair consisting only of posterior leaflet resection (quadrangular in 28 and sliding in 65) and annuloplasty (Cosgrove-Edwards in 83, pericardial in 9, and Carpentier-Edwards in 1). All patients had severe mitral regurgitation documented by intraoperative TEE. Mean age was 55+/-13 years; 60% were men. RESULTS: Postrepair, mitral regurgitation was 0 to trace in 93% and 1+ in 7%. There were no operative deaths. Late follow-up was available in all patients, with 277 patient-years of follow-up available for analysis. Five-year actuarial survival was 95%. At a mean interval of 2.3+/-1.3 (SD) years, echocardiography demonstrated no or trace mitral regurgitation in 65%, 1+ in 28%, and 2+ in 7%. No correlates of late mitral regurgitation were identified by multivariable analysis. No patient has required reoperation. CONCLUSIONS: In the absence of significant anterior chordal pathology, a strategy of posterior leaflet resection and annuloplasty corrects anterior leaflet prolapse and mitral regurgitation, and provides a durable repair without the necessity of additional procedures on the anterior leaflet.

Aged↗
PubMed1999

Two internal thoracic artery grafts are better than one.

OBJECTIVE: Does the use of bilateral internal thoracic artery (ITA) grafts provide incremental benefit relative to the use of a single ITA graft? METHODS: We conducted a retrospective, nonrandomized, long-term (mean follow-up interval of 10 postoperative years) study of patients undergoing elective primary isolated coronary bypass surgery who received either single (8123 patients) or bilateral ITA grafts (2001 patients), with or without additional vein grafts. Multiple statistical methods including propensity score matching, and multivariable parsimonious and nonparsimonious risk factor analyses were used to address the issues of patient selection and heterogeneity. RESULTS: In-hospital mortality was 0.7% for both the bilateral and single ITA groups. Survival for the bilateral ITA group was 94%, 84%, and 67%, and for the single ITA group 92%, 79%, and 64% at 5, 10, and 15 postoperative years, respectively (P <.001). Death, reoperation, and percutaneous transluminal coronary angioplasty were more frequent for patients undergoing single rather than bilateral ITA grafting, and this observation remained true despite multiple adjustments for patient selection, sampling, and length of follow-up. The differences between the bilateral and single ITA groups were greatest in regard to reoperation. The extent of benefit of bilateral ITA grafting varied according to patient-related variables, but no patient subsets were identified for whom single ITA grafting could be predicted to provide an advantage. CONCLUSIONS: Patients who received 2 ITA grafts had decreased risks of death, reoperation, and angioplasty.

Aged↗
PubMed1999

Dissection of the ascending aorta after previous cardiac surgery: differences in presentation and management.

OBJECTIVE: This study was undertaken to determine the impact of previous cardiac surgery on the presentation, management, and outcome of late dissection of the ascending aorta. PATIENTS AND METHODS: From 1976 to 1998, type A dissection developed in 56 patients with a history of previous cardiac surgery. Interval from first operation to type A dissection was 49 +/- 47 months (0.3-180 months). Previous operations were coronary artery bypass grafting (n = 40), aortic valve replacement (n = 8), and other (n = 8). RESULTS: Type A dissection was acute in 34 patients and chronic in 22. In acute dissection, aortic insufficiency occurred in 50%, malperfusion in 12%, and rupture in 18%; 2 patients (6%) were in hemodynamically unstable condition because of rupture. Of patients with previous coronary bypass grafting, 98% had preoperative coronary angiography. Type A dissection was treated by supracoronary tube graft (84%), Bentall procedure (14%), or local repair (2%). Strategies for managing previous coronary bypass grafting included reimplantation of proximal anastomoses with a button of native aorta (29 patients), interposition graft to pre-existing saphenous vein grafts (9 patients), and new saphenous vein grafts (20 patients). Eight hospital deaths occurred (14%). CONCLUSIONS: We conclude that (1) patients having type A dissection late after cardiac surgery infrequently have cardiac tamponade and hemodynamic collapse; (2) patients with previous coronary bypass grafting require coronary angiography, because operative management must account for pre-existing coronary artery disease; and (3) operative mortality is low, and this may be attributable to preoperative hemodynamic stability, delineation of coronary anatomy in those with previous coronary bypass grafting, and operative treatment of coronary artery disease.

Aged↗
PubMed1999

Functional status and quality of life in patients with heart failure undergoing coronary bypass surgery after assessment of myocardial viability.

OBJECTIVES: The aim of this study was to evaluate whether preoperative clinical and test data could be used to predict the effects of myocardial revascularization on functional status and quality of life in patients with heart failure and ischemic LV dysfunction. BACKGROUND: Revascularization of viable myocardial segments has been shown to improve regional and global LV function. The effects of revascularization on exercise capacity and quality of life (QOL) are not well defined. METHODS: Sixty three patients (51 men, age 66+/-9 years) with moderate or worse LV dysfunction (LVEF 0.28+/-0.07) and symptomatic heart failure were studied before and after coronary artery bypass surgery. All patients underwent preoperative positron emission tomography (PET) using FDG and Rb-82 before and after dipyridamole stress; the extent of viable myocardium by PET was defined by the number of segments with metabolism-perfusion mismatch or ischemia. Dobutamine echocardiography (DbE) was performed in 47 patients; viability was defined by augmentation at low dose or the development of new or worsening wall motion abnormalities. Functional class, exercise testing and a QOL score (Nottingham Health Profile) were obtained at baseline and follow-up. RESULTS: Patients had wall motion abnormalities in 83+/-18% of LV segments. A mismatch pattern was identified in 12+/-15% of LV segments, and PET evidence of viability was detected in 30+/-21% of the LV. Viability was reported in 43+/-18% of the LV by DbE. The difference between pre- and postoperative exercise capacity ranged from a reduction of 2.8 to an augmentation of 5.2 METS. The degree of improvement of exercise capacity correlated with the extent of viability by PET (r = 0.54, p = 0.0001) but not the extent of viable myocardium by DbE (r = 0.02, p = 0.92). The area under the ROC curve for PET (0.76) exceeded that for DbE (0.66). In a multiple linear regression, the extent of viability by PET and nitrate use were the only independent predictors of improvement of exercise capacity (model r = 0.63, p = 0.0001). Change in Functional Class correlated weakly with the change in exercise capacity (r = 0.25), extent of viable myocardium by PET (r = 0.23) and extent of viability by DbE (r = 0.31). Four components of the quality of life score (energy, pain, emotion and mobility status) significantly improved over follow-up, but no correlations could be identified between quality of life scores and the results of preoperative testing or changes in exercise capacity. CONCLUSIONS: In patients with LV dysfunction, improvement of exercise capacity correlates with the extent of viable myocardium. Quality of life improves in most patients undergoing revascularization. However, its measurement by this index does not correlate with changes in other parameters nor is it readily predictable.

Aged↗
PubMed1998

Spectrum of surgical risk for left main coronary stenoses: benchmark for potentially competing percutaneous therapies.

Coronary artery bypass grafting is the preferred therapy for left main trunk coronary stenoses because of a demonstrated survival advantage compared with medical therapy. Recently, however, advocates of percutaneous intervention have suggested that stenting or atherectomy may provide acceptable results for these patients. To determine the spectrum of surgical outcome among patients with left main trunk coronary stenoses, we analyzed 14 potential covariates of in-hospital and 3-year mortality for a consecutive series of patients without prior coronary artery bypass grafting treated at our institution from January 1990 to December 1995. In-hospital mortality (2.3%) for 1585 consecutively treated patients correlated independently with renal dysfunction, age, and class III to IV heart failure. A model was constructed that allowed prediction of outcome (c-statistic = 0.77, p < 0.0001), and only the 9% of patients at highest risk were found to be at risk for death >5%. Mortality at 3 years (15.6%+/-2.2%) in a previously specified subgroup (n = 285) correlated independently with baseline age, renal dysfunction, and chronic pulmonary disease. A model was constructed that allowed prediction of outcome for the validation sample (four risk groups with 3-year mortality rates of 4.5%+/-2.5%, 6.5%+/-2.8%, 20.0%+/-4.2%, and 39.8%+/-8.5%; p < 0.0001. These data provide a contemporary benchmark of clinical outcome against which possible competing therapies may be compared.

Aged↗
PubMed1998

Relative efficacy of medical therapy and revascularization for improving exercise capacity in patients with chronic left ventricular dysfunction.

BACKGROUND: In patients with left ventricular dysfunction one of the aims of therapy may be to improve functional capacity. This study compared the improvement of functional capacity in response to medical therapy with that caused by revascularization. METHODS: Fifty-two patients with severe left ventricular dysfunction were divided into groups with ischemic cardiomyopathy undergoing revascularization (group A, n = 20) or incremental medical treatment (group B, n = 16) and a control group receiving maximal medical therapy at the start of the study (group C, n = 16). All patients underwent a baseline metabolic exercise test with evaluation of peak oxygen consumption and derived exercise capacity in metabolic equivalents (METS) with standard electrocardiographic and hemodynamic monitoring. Therapy was then optimized in the medical treatment group, whereas the revascularization group underwent coronary bypass grafting. All patients subsequently underwent follow-up metabolic exercise testing. RESULTS: In groups A, B, and C resting left ventricular ejection fractions were comparable (26%+/-5%, 25%+/-7%, and 23%+/-8%, respectively), as were results of initial metabolic exercise tests (4.7+/-0.9 METS, 4.7+/-1.4 METS, and 5.2+/-1.4 METS). At follow-up group A improved exercise capacity from 4.7 to 5.6 METS (p = 0.01). Groups B (4.7 to 5.0 METS) and C (5.2 to 5.6 METS) had no significant improvement. The mean respiratory exchange ratio improved significantly in group A (1.14 to 1.20, p = 0.02), as did left ventricular ejection fraction (26% to 31%, p = 0.02). However, neither parameter changed significantly in groups B or C. CONCLUSIONS: In patients with severe left ventricular dysfunction improvements of exercise capacity are more marked after coronary revascularization than may be obtained after maximization of medical therapy.

Adult↗
PubMed1998

Increased risk and decreased morbidity of coronary artery bypass grafting between 1986 and 1994.

BACKGROUND: The collective impact of advances in medical, surgical, and anesthetic care on the characteristics and outcomes of patients who undergo coronary artery bypass grafting was assessed. METHODS: We compared the demographic and clinical characteristics, preoperative risk factors, morbidity, and mortality of two groups of patients who underwent coronary artery bypass grafting in isolation or in combination with other procedures between July 1, 1986, and June 30,1988 (group 1, n = 5,051), and between January 1, 1993, and March 31, 1994 (group 2, n = 2,793). The patients were stratified according to their preoperative risk level. Outcome measures consisted of changes in preoperative risk categories; hospital mortality rates; overall and risk-adjusted major cardiac, neurologic, pulmonary, renal, and septic morbidity rates; and intensive care unit length of stay. RESULTS: Changes in the distribution of risk categories, from a median of 2 to 4 on a 9-point scale (p < 0.001), indicated that patients in group 2 were at significantly higher risk than those in group 1. The risk-adjusted mortality rate did not change (2.8% to 2.9%; p = 0.15), but the risk-adjusted morbidity rate decreased significantly (14.5% to 8.8%; p < 0.001). CONCLUSIONS: At our institution, patients who undergo coronary artery bypass grafting are now at greater preoperative risk at the time of hospital admission. However, their morbidity rate is significantly lower and their mortality rate is unchanged, results that we attribute to the collective impact of changes in our medical and surgical procedures.

Aged↗
PubMed1998

Aortic valve replacement for octogenarians: are small valves bad?

BACKGROUND: As the population ages, more octogenarians become candidates for aortic valve replacement. Many octogenarians, particularly women, have a small aortic annulus and there is uncertainty as to the optimal management of this situation in that age group. METHOD: To examine this issue, we reviewed 248 octogenarians (mean age, 82.6 +/- 2.3 years; 58% men) who underwent primary isolated aortic valve replacement (n = 99), or aortic valve replacement and coronary revascularization (n = 149), between 1980 and 1995. Nineteen-millimeter valves were used in 26% of the patients. RESULTS: In-hospital mortality was 8.9%, 5% for aortic valve replacement alone and 11.4% for aortic valve replacement and coronary revascularization. It was 12.5% for the 19-mm size valves compared with 7.7% for the bigger size valves (p = 0.24). Follow-up (mean interval, 4.4 years) demonstrated survival for all patients of 85%, 60%, and 30% and survival free from cardiovascular events of 80%, 45%, and 21% at 1, 5, and 10 postoperative years, respectively. Multivariate analysis identified triple-vessel disease and preoperative congestive heart failure as associated with increased risk for both in-hospital and late mortality (p < 0.05). Valve size did not influence late survival or event-free survival regardless of body surface area. CONCLUSIONS: The use of small aortic valve prostheses in octogenarians does not adversely affect the incidence of early or late mortality or cardiac events.

Aged↗
PubMed1998

Long-term results of the Carpentier-Edwards pericardial aortic valve: a 12-year follow-up.

BACKGROUND: Pericardial valves have excellent hemodynamic function; however, long-term durability is questionable. To determine the function of the Carpentier-Edwards pericardial valve in the aortic position, the results of 310 aortic valve replacements performed between 1982 and 1985 were analyzed. Mean age was 64.2+/-10.8 years (range, 22 to 95 years); 190 (61.3%) were men. Isolated valve replacement was performed in 135 patients (43.5%). There were 18 hospital deaths (5.8%), none of them valve related. METHODS: Follow-up of 292 survivors was 100% complete at a mean of 8.8 years; 2,556 patient-years of follow-up were analyzed. There were 150 late deaths (51.4%). Survival at 5, 10, and 12 years were 83%+/-2%, 47%+/-3%, and 34%+/-3%, respectively. The 12-year actuarial and actual freedom from thromboembolism was 87%+/-2% and 89%+/-2%, respectively. Freedom from hemorrhage was 91%+/-2% and 92%+/-2%; freedom from endocarditis was 93%+/-2% and 95% +/- 1%; and freedom from structural deterioration was 82%+/-4% and 91%+/-2%, respectively. RESULTS: Actuarial freedom from structural deterioration at 12 years was considerably higher for 153 hospital survivors 65 years or older, 93% (5 explants) compared to 76% (19 explants) for patients younger than 65 years, p = 0.03. Of 24 explanted valves for structural deterioration, leaflet calcification resulting in stenosis occurred in 20 (83%) and 4 were wear-related leaflet tears. CONCLUSIONS: We conclude that the Carpentier-Edwards pericardial valve has a low incidence of valve-related complications, that structural deterioration is infrequent and results from leaflet calcification, and that the low incidence of structural deterioration in patients 65 years or older makes this an increasingly appropriate option in this age group.

Actuarial Analysis↗