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Biomedical subjects

Gary L Grunkemeier

Publications and source records attributed to Gary L Grunkemeier.

At least 37 records · Page 2Linked to original sources
PubMed2004

Sternal preservation: a better way to treat most sternal wound complications after cardiac surgery.

BACKGROUND: Postcardiotomy sternal wound complications remain challenging. The prevailing approach for deep sternal wound infection of debridement and flap coverage without osseous closure makes subsequent reoperation difficult. METHODS: An analysis of all patients undergoing cardiac surgery at a single institution between 1986 and 2001 was conducted. Prospective data collection and chart review were used to compare different treatment strategies for sternal complications. RESULTS: Of 5337 patients, 122 had sternal wound complications (2.2%) comprising 15 (0.3%) uninfected dehiscences (El Oakley class 1), 45 (0.8%) superficial infections (El Oakley class 2A), and 62 (1.1%) deep sternal wound infections (El Oakley class 2B). Thirty-two patients with deep sternal infection were treated by debridement, rewiring, and delayed primary closure. There were initial treatment failures in 6 patients (18.8%) and ultimate failures in 2 patients (6.3%), both of whom died. One of these patients had previously received external beam radiation after a radical mastectomy for breast cancer. Median length of stay was 32 days and median time to wound healing was 85 days. Twenty-five patients were managed by muscle flap coverage without sternal reclosure. There were 6 initial treatment failures (24%) but no ultimate failures or deaths (p = NS). Median length of stay was 31 days and median infection time was 161 days. CONCLUSIONS: In patients with postcardiotomy deep sternal wound infection without previous chest radiation, debridement, rewiring, and delayed skin closure is effective. It offers a shorter healing time and probably makes late cardiac reoperation safer. We propose an algorithm for the management of poststernotomy complications.

Algorithms↗
PubMed2004

Cardiac surgery risk models: a position article.

Differences in medical outcomes may result from disease severity, treatment effectiveness, or chance. Because most outcome studies are observational rather than randomized, risk adjustment is necessary to account for case mix. This has usually been accomplished through the use of standard logistic regression models, although Bayesian models, hierarchical linear models, and machine-learning techniques such as neural networks have also been used. Many factors are essential to insuring the accuracy and usefulness of such models, including selection of an appropriate clinical database, inclusion of critical core variables, precise definitions for predictor variables and endpoints, proper model development, validation, and audit. Risk models may be used to assess the impact of specific predictors on outcome, to aid in patient counseling and treatment selection, to profile provider quality, and to serve as the basis of continuous quality improvement activities.

Bayes Theorem↗
PubMed2004

Outcomes after usage of a quality initiative program for off-pump coronary artery bypass surgery: a comparison with on-pump surgery.

BACKGROUND: Off-pump coronary artery bypass (OPCAB) may be associated with improved outcomes when compared with on-pump coronary artery bypass. This study evaluates the use of a system for access and stabilization (SAS) with a coronary stabilizer as well as a clinical effectiveness quality initiative (CEQI) process regarding outcomes. This included the development of an expanded heart care team as well as standardization and refinement of perioperative care at The Lankenau Hospital (TLH). Our aim was to evaluate morbidity and mortality of on-pump coronary artery bypass grafting (CABG) compared with OPCAB surgery using SAS in addition to a CEQI initiative. METHODS: A retrospective consecutive cohort study using the Society of Thoracic Surgery (STS) National Database was conducted. Three cohorts were analyzed: pre-SAS (December 1, 1999-August 31, 2000); use of SAS only (September 1, 2000-April 30, 2001), and the use of SAS + CEQI process (May 1, 2001-September 30, 2002). Morbidity and mortality for all on-pump CABG procedures performed over the time period of December 1, 1999-September 30, 2002 were compared with the SAS and SAS + CEQI groups only. RESULTS: One-thousand two-hundred sixty-seven procedures were performed; 405 on-pump CABGs, 90 OPCABs pre-SAS, and 772 OPCABs with SAS, of which 552 were in the SAS + CEQI group. Statistically mortality was significantly lower in the SAS + CEQI vs the on-pump group (0.7% vs 3.0%, p < 0.01). The percentage of patients with prolonged ventilation was significantly lower statistically in the SAS + CEQI vs the on-pump group (4.2% vs 9.7%, p < 0.01). Statistically the length of stay was significantly lower in both SAS groups compared with the on-pump group (p < 0.01). CONCLUSIONS: OPCAB surgery using SAS in conjunction with a CEQI initiative improves outcomes for patients compared with on-pump CABG surgery.

Cohort Studies↗
PubMed2004

The Silzone effect: how to reconcile contradictory reports?

OBJECTIVE: To attempt to reconcile reports containing contradictory findings with the St. Jude Medical Silzone heart valve. METHODS: Major leak and thromboembolism data were extracted from available Silzone valve studies. Linearized rates were used to summarize and compare the events rates among the studies. RESULTS: The Artificial Valve Endocarditis Reduction Trial (AVERT) study reported significant higher rate of major leak and the Cardiff Embolic Risk Factor Study (CERFS) reported significant higher rate of thromboembolism with Silzone compared to non-Silzone valves. But, current updates of these studies show a diminution of these differences. Three other comparative studies reported no difference between Silzone and non-Silzone valves, and three single arm studies reported acceptable results with Silzone valves. CONCLUSION: The contradictory findings could be partly due to clinical and technical reasons. No new events have been reported since the original AVERT (major leak) and CERFS (mitral thromboembolism) publications.

Endocarditis↗
PubMed2004

Coronary artery bypass grafting: are risk models developed from on-pump surgery valid for off-pump surgery?

OBJECTIVE: This study was undertaken to test whether risk models developed from on-pump coronary artery bypass grafting are valid for assessing the risk for off-pump coronary artery bypass grafting. METHODS: From January 1997 through June 2002, a total of 12,845 patients underwent isolated coronary artery bypass grafting procedures in Providence Health System hospitals. Of these, 1782 operations (14%) were performed without cardiopulmonary bypass. An operative mortality risk model was derived from on-pump data with logistic regression. This model and two other external risk models developed from on-pump data were then applied to patients undergoing off-pump coronary artery bypass grafting to test the model adequacy. RESULTS: Good model discrimination and calibration were obtained from all three models. CONCLUSION: Operative mortality risk models developed from on-pump coronary artery bypass grafting can be used to assess the risk for off-pump coronary artery bypass grafting.

Aged↗
PubMed2004

Forty-year survival with the Starr-Edwards heart valve prosthesis.

BACKGROUND AND AIM OF THE STUDY: The study aim was to update an analysis of the long-term survival of heart valve replacement using the Starr-Edwards prosthesis. METHODS: Cases of isolated aortic (AVR, n = 2,247) and mitral (MVR, n = 1,406) valve replacement with Starr-Edwards prostheses implanted between 1960 and 1997, with follow up to 2003, were reviewed. Introduced in 1965, the Models A1200/1260, M6120 are still in use (Current), while other models have been discontinued (Discontinued). For AVR, 938 valves were Discontinued, with a total follow up of 8,506 patient-years (pt-yr) and a maximum of 41 years; by comparison, 1,309 valves were Current, with a total follow up of 11,586 pt-yr and a maximum of 36.1 MVR, were Discontinued, with a total follow up of 6,454 pt-yr and maximum of 37.2 years; and 771 valves were Current, with a total follow up of 6,211 pt-yr and maximum of 37.0 years. RESULTS: Kaplan-Meier (KM) survival at 10 years was 53% for AVR and 51% for MVR; KM survival at 20 years was 23% for both AVR and MVR; KM survival at 30 years was 8% for both AVR and MVR; KM survival at 40 years was 4% for AVR. The standard error for all KM percentages was 1%. Four patients are currently alive with their original valves, more than 40 years after implantation. CONCLUSION: This series of patients, who underwent valve replacement with the Starr-Edwards valve, now have a follow up extending beyond 40 years, thereby confirming the excellent durability of this valve.

Actuarial Analysis↗
PubMed2003

A new scoring system to determine thromboembolic risk after heart valve replacement.

OBJECTIVE: To determine the most important inflammatory and hematologic predictors of thromboembolism (TE) in patients undergoing valve replacement (VR) to be used in conjunction with clinical risk factors for preoperative risk profiling. METHODS AND RESULTS: Preoperative and immediately postoperative clinical, echocardiographic, hematologic, biochemical and microbiological parameters were examined prospectively in 370 patients undergoing VR (249 AVR, 93 MVR, 28 DVR). Mean follow-up was 4.4 years (max 6.6 years; total 1566 pt/yrs), and 96 TE events were documented (28 major and 68 minor). INR data were collected on all patients. Laboratory values were considered elevated if they exceeded the 80th percentile of those of 70 controls with the same distribution of age and gender. IgA antibody to Chlamydia pneumoniae (CP)>or=1:64 was considered indicative of significant infection. Predictors of TE on multivariate analysis following AVR were (hazard ratios): CP infection (2.6), previous TE (2.5), raised eosinophils (2.4), cancer history (2.1), postoperative infection (2.0), hypertension (2.0), CABG x 3/4 (2.0), and diabetes (1.9). Predictors of TE following MVR/DVR were raised mean platelet volume (4.0), raised factor VII (3.1), CP infection (2.7), previous mitral valvotomy (2.5), raised fibrinogen (2.2), and raised reticulocytes (2.0). These risk factors were additive when present in the same patient, enabling a scoring system to be developed that accurately predicted risk of TE based on number of risk factors. CONCLUSIONS: Selected blood tests and clinical risk factors provide a scoring system that accurately predicts TE risk and may guide prosthesis choice and antithrombotic management.

Aged↗
PubMed2003

Choice of a mechanical valve or a bioprosthesis for AVR: does CABG matter?

OBJECTIVE: Mechanical valves and bioprostheses are the commonly used devices in aortic valve replacement (AVR). Many patients with valvular disease also require concomitant coronary artery bypass grafting (CABG). We used a microsimulation model to provide insight into the outcomes of patients after AVR with mechanical valves and stented bioprostheses, with and without CABG, and to determine the age-thresholds or age crossover points in outcomes between the two valve types. METHODS: We conducted a meta-analysis of published results after primary AVR with mechanical prostheses (nine reports, 4274 patients, 25,726 patient-years) and stented porcine bioprostheses (13 reports, 9007 patients, 54,151 patient-years) to estimate risks of valve-related events. A hazard ratio of 1.3 was used to incorporate the effect of CABG on long-term survival. Estimates were entered into a microsimulation model, which was then used to predict the outcomes of patients after AVR, with and without CABG. The model calculations were validated using a large data set from Portland, USA. RESULTS: For a 65-year-old male without CABG, the life expectancy (LE) was 11.2 and 11.6 years and the event-free life expectancy (EFLE) was 8.2 and 8.9 years, respectively, after implantation with mechanical valves and bioprostheses. The lifetime risk of at least one valve-related event was 51 and 47%, respectively. The age crossover point between the two valve types, considering the above outcome parameters, was 59, 60 and 63 years, respectively. CABG reduced LE and consequently EFLE and lifetime risk of an event, but only minimally influenced the patient age crossover points. The model calculations showed good agreement with the Portland data. CONCLUSIONS: The currently recommended patient age for using a bioprosthesis (65 years) could be lowered further, irrespective of concomitant CABG. The trade-off between the reduced risks of bioprosthetic failure and of hemorrhage in mechanical valves, resulting from a lower LE, minimized the effect of CABG on the age crossover points between the two valve types.

Adolescent↗
PubMed2003

Continuous insulin infusion reduces mortality in patients with diabetes undergoing coronary artery bypass grafting.

OBJECTIVE: Diabetes mellitus is a risk factor for death after coronary artery bypass grafting. Its relative risk may be related to the level of perioperative hyperglycemia. We hypothesized that strict glucose control with a continuous insulin infusion in the perioperative period would reduce hospital mortality. METHODS: All patients with diabetes undergoing coronary artery bypass grafting (n = 3554) were treated aggressively with either subcutaneous insulin (1987-1991) or with continuous insulin infusion (1992-2001) for hyperglycemia. Predicted and observed hospital mortalities were compared with both internal and external (Society of Thoracic Surgeons 1996) multivariable risk models. RESULTS: Observed mortality with continuous insulin infusion (2.5%, n = 65/2612) was significantly lower than with subcutaneous insulin (5.3%, n = 50/942, P <.0001). Likewise, glucose control was significantly better with continuous insulin infusion (177 +/- 30 mg/dL vs 213 +/- 41 mg/dL, P <.0001). For internal comparison, multivariable analysis showed that continuous insulin infusion was independently protective against death (odds ratio 0.43, P =.001). Conversely, cardiogenic shock, renal failure, reoperation, nonelective operative status, older age, concomitant peripheral or cerebral vascular disease, decreasing ejection fraction, unstable angina, and history of atrial fibrillation increased the risk of death. For external comparison, observed mortality with continuous insulin infusion was significantly less than that predicted by the model (observed/expected ratio 0.63, P <.001). Multivariable analysis revealed that continuous insulin infusion added an independently protective effect against death (odds ratio 0.50, P =.005) to the constellation of risk factors in the Society of Thoracic Surgeons risk model. CONCLUSION: Continuous insulin infusion eliminates the incremental increase in in-hospital mortality after coronary artery bypass grafting associated with diabetes. The protective effect of continuous insulin infusion may stem from the effective metabolic use of excess glucose to favorably alter pathways of myocardial adenosine triphosphate production. Continuous insulin infusion should become the standard of care for glycometabolic control in patients with diabetes undergoing coronary artery bypass grafting.

Aged↗
PubMed2003

"Our complication rates are lower than theirs": statistical critique of heart valve comparisons.

OBJECTIVES: From the widely differing complication rates published for every heart valve, is it possible to determine a true rate for each valve and to compare the rates of two different valves? We investigated this question for the two most popular bileaflet valves. METHODS: Aortic valve data were abstracted from 14 St Jude Medical (St Jude Medical Inc, Minneapolis, Minn; 33,125 patient-y) and 11 Carbomedics (Sulzer Carbomedics Inc, Austin, Tex; 19,141 patient-y) series, and mitral valve data were abstracted from 11 St Jude Medical (21,553 patient-y) and 8 Carbomedics (8368 patient-y) series. Regression analysis was used to accommodate heterogeneity among rates with the same valve model, to estimate hazard ratios and 95% confidence intervals for the valve model effect, and to incorporate other series-level risk factors. RESULTS: Most of the complication rates with both valve models exhibited significant heterogeneity. For thromboembolism and bleeding, the relative risks for valve model were not significantly different from unity. Valve thrombosis rates exhibited less heterogeneity: the Carbomedics valve had a lower rate in the aortic position (hazard ratio 0.2, 95% confidence interval 0.1-0.6) and a higher rate in the mitral position (hazard ratio 1.9, 95% confidence interval 1.0-3.8). CONCLUSIONS: Unlike simple weighted averages of valve complication rates, regression methods can incorporate heterogeneity related to center effects and allow for inclusion of other risk factors. Thromboembolism and bleeding rates were not significantly different with St Jude Medical and Carbomedics valves. Valve thrombosis appeared to differ between the two valves, but the absolute differences in rates were small. Because of the variability among rates with the same valve, statistical comparisons must be interpreted cautiously.

Aortic Valve↗
PubMed2003

Statistical analysis of the results of heart valve replacement.

A variety of statistical methods can be used to analyze the results of heart valve replacement. In this review, we illustrate the methodology and the application of the techniques that are most widely used. For early events, univariate analysis and multivariate logistic regression are illustrated. For late (time-related) events, nonparametric methods (Kaplan-Meier and cumulative incidence or 'actual' analysis), parametric methods (based on the exponential, Gompertz and Weibull distributions) and semiparametric methods (Cox proportional hazards) are illustrated.

Aged↗
PubMed2002

Paravalvular leak and other events in silzone-coated mechanical heart valves: a report from AVERT.

BACKGROUND: The Artificial Valve Endocarditis Reduction Trial (AVERT) was designed to compare endocarditis rates in Silzone versus conventional valves. Recruitment ended January 21, 2000, because of higher rates of paravalvular leakage in patients receiving the Silzone prosthesis. The present analysis determined late event rates that might be used in the management of approximately 36,000 patients who have received the Silzone prosthesis. METHODS: A total of 807 patients in 19 centers in North America and Europe were randomized. Mean age was 61+/-11 years; 41% were women. Operations included aortic valve replacement in 59%, mitral valve replacement in 32%, and aortic and mitral valve replacements in 9%; 41% had concomitant operations (26% coronary artery bypass grafting). RESULTS: Major paravalvular leakage (followed by repair, explant, or mortality) occurred in 18 of 403 patients receiving Silzone valves and 4 of 404 patients without Silzone valves (2-year event-free rates: 91.1% versus 98.9% conventional, p < 0.003). Similarly, 2-year freedom from any explant was lower in the Silzone arm (19 versus 2 events; 90.1% versus 99.4%, p = 0.0002). Rates of mortality and stroke were similar during follow-up. CONCLUSIONS: Continued follow-up of AVERT supports the conclusion that the Silzone prosthesis has increased risk of paravalvular leakage requiring reoperation. Overall survival is similar in the two groups.

Aortic Valve↗
PubMed2002

Bayesian analysis: a new statistical paradigm for new technology.

Full Bayesian analysis is an alternative statistical paradigm, as opposed to traditionally used methods, usually called frequentist statistics. Bayesian analysis is controversial because it requires assuming a prior distribution, which can be arbitrarily chosen; thus there is a subjective element, which is considered to be a major weakness. However, this could also be considered a strength since it provides a formal way of incorporating prior knowledge. Since it is flexible and permits repeated looks at evolving data, Bayesian analysis is particularly well suited to the evaluation of new medical technology. Bayesian analysis can refer to a range of things: from a simple, noncontroversial formula for inverting probabilities to an alternative approach to the philosophy of science. Its advantages include: (1) providing direct probability statements--which are what most people wrongly assume they are getting from conventional statistics; (2) formally incorporating previous information in statistical inference of a data set, a natural approach which we follow in everyday reasoning; and (3) flexible, adaptive research designs allowing multiple looks at accumulating study data. Its primary disadvantage is the element of subjectivity which some think is not scientific. We discuss and compare frequentist and Bayesian approaches and provide three examples of Bayesian analysis: (1) EKG interpretation, (2) a coin-tossing experiment, and (3) assessing the thromboembolic risk of a new mechanical heart valve.

Bayes Theorem↗