Extracorporeal membrane oxygenation (ECMO), a rescue therapy for pulmonary failure, has traditionally been limited by anticoagulation requirements. Recent practice has challenged the absolute need ...for anticoagulation, expanding the role of ECMO to patients with higher bleeding risk. We hypothesize that mortality, bleeding, thrombotic events, and transfusions do not differ between heparin-sparing and full therapeutic anticoagulation strategies in veno-venous (VV) ECMO management.
Adult VV ECMO patients between October 2011 and May 2018 at a single center were reviewed. A heparin-sparing strategy was implemented in October 2014; we compared outcomes in an as-treated fashion. The primary end point was survival. Secondary end points included bleeding, thrombotic complications, and transfusion requirements.
Forty VV ECMO patients were included: 17 (147 circuit-days) before and 23 (214 circuit-days) after implementation of a heparin-sparing protocol. Patients treated with heparin-sparing anticoagulation had a lower body mass index (28.5 ± 7.1 versus 38.1 ± 12.4, P = 0.01), more often required inotropic support before ECMO (82 versus 50%, P = 0.05), and had a lower mean activated clotting time (167 ± 15 versus 189 ± 15 s, P < 0.01). There were no significant differences in survival to decannulation (59 versus 83%, P = 0.16) or discharge (50 versus 72%, P = 0.20), bleeding (32 versus 33%, P = 1.0), thromboembolic events (18 versus 39%, P = 0.17), or transfusion requirements (median 1.1 versus 0.9 unit per circuit-day, P = 0.48).
Survival, bleeding, thrombotic complications, and transfusion requirements did not differ between heparin-sparing and full therapeutic heparin strategies for management of VV ECMO. VV ECMO can be a safe option in patients with traditional contraindications to anticoagulation.
Limited data exist that compare the predominant cardiac preservation solutions (CPSs).
The United Network for Organ Sharing database was retrospectively reviewed from January 1, 2004 to March 31, ...2018, for donor hearts. Of 34,614 potential donors, 21,908 remained after applying the exclusion criteria. The CPS analyzed included saline, the University of Wisconsin (UW), cardioplegia, Celsior, and Custodiol. The primary endpoints were recipient survival and posttransplant rejection. Logistic and Cox models were used to quantify survival endpoints.
Saline was used as the CPS in 2549 patients (12%), UW in 10,549 (48%), cardioplegia in 1307 (6%), Celsior in 5081 (23%), and Custodiol in 2422 (11%). Donor age ranged from 15 to 68 y (mean = 32.0 y, median = 30.0 y), and 71% were male. Adjusted survival probabilities of recipients whose donor hearts were procured with saline was 96% 30 d, 90% 1 y, UW: 97% 30 d, 92% 1 y, cardioplegia: 95% 30 d, 87% 1 y, Celsior: 96% 30 d, 90% 1 y, and Custodiol: 97% 30 d, 92% 1 y. When these comparisons were adjusted for donor age, sex, ethnicity, ischemic time, recipient age, sex, ethnicity, creatinine, ventricular assist device (VAD), length of stay, region and days on waiting list, cardioplegia solution was demonstrated to have a higher risk of death (30 d, 1 y, overall) and posttransplant rejection versus UW (odds ratio 1.70, P = 0.001; odds ratio 1.63, P < 0.001; hazard ratio 1.22, P < 0.001; hazard ratio 1.21, P < 0.001, respectively).
Cardioplegia solutions for cardiac preservation are associated with a higher mortality in heart transplant recipients.
Numerical models of native heart valves are being used to study valve biomechanics to aid design and development of repair procedures and replacement devices. These models have evolved from simple ...two-dimensional approximations to complex three-dimensional, fully coupled fluid–structure interaction (FSI) systems. Such simulations are useful for predicting the mechanical and hemodynamic loading on implanted valve devices. A current challenge for improving the accuracy of these predictions is choosing and implementing modeling boundary conditions. In order to address this challenge, we are utilizing an advanced
in vitro
system to validate FSI conditions for the mitral valve system. Explanted ovine mitral valves were mounted in an
in vitro
setup, and structural data for the mitral valve was acquired with
μ
CT. Experimental data from the
in vitro
ovine mitral valve system were used to validate the computational model. As the valve closes, the hemodynamic data, high speed leaflet dynamics, and force vectors from the
in vitro
system were compared to the results of the FSI simulation computational model. The total force of 2.6 N per papillary muscle is matched by the computational model.
In vitro
and
in vivo
force measurements enable validating and adjusting material parameters to improve the accuracy of computational models. The simulations can then be used to answer questions that are otherwise not possible to investigate experimentally. This work is important to maximize the validity of computational models of not just the mitral valve, but any biomechanical aspect using computational simulation in designing medical devices.
•The validity of the KTada solution for the pinned SEN(T) is evaluated.•Measured da/dN reductions demonstrate that the true K can deviate below KTada.•FE calculations quantify the influence of ...non-linear geometry effects on KTada.•Most pinned SEN(T) data are valid due to low a/W, low KTada, and high alloy modulus.•A new K solution is needed to cover broader ranges of a/W, load, and alloy modulus.
The validity of the Tada stress intensity factor (KTada) for pinned-ends single edge notch tension SEN(T) specimens is assessed via a combined experimental-modeling approach. Analysis of fatigue crack growth rate reductions during constant-ΔKTada loading demonstrates that specific combinations of alloy stiffness, geometry, and loading result in the true K deviating below KTada. Geometrically non-linear, 3-dimensional finite element calculations confirm mild-to-strong influences of these parameters, which are not captured by KTada. Most existing pinned SEN(T) data are found to use parameters where KTada is not significantly reduced, but the present results underscore the need for a more broadly applicable K solution.
Edge-to-edge repair for mitral valve regurgitation is being increasingly performed in high-surgical risk patients using minimally invasive mitral clipping devices. Known procedural complications ...include chordal rupture and mitral leaflet perforation. Hence, it is important to quantitatively evaluate the effect of edge-to-edge repair on chordal integrity. in this study, we employ a computational mitral valve model to simulate functional mitral regurgitation (FMR) by creating papillary muscle displacement. Edge-to-edge repair is then modeled by simulated coaptation of the mid portion of the mitral leaflets. in the setting of simulated FMR, edge-to-edge repair was shown to sustain low regurgitant orifice area, until a two fold increase in the inter-papillary muscle distance as compared to the normal mitral valve. Strain in the chordae was evaluated near the papillary muscles and the leaflets. Following edge-to-edge repair, strain near the papillary muscles did not significantly change relative to the unrepaired valve, while strain near the leaflets increased significantly relative to the unrepaired valve. These data demonstrate the potential for computational simulations to aid in the pre-procedural evaluation of possible complications such as chordal rupture and leaflet perforation following percutaneous edge-to-edge repair.
Renal insufficiency after coronary artery bypass graft (CABG) surgery is associated with increased short-term and long-term mortality. We hypothesized that preoperative patient characteristics could ...be used to predict the patient-specific risk of developing postoperative renal insufficiency.
Data were prospectively collected on 11,301 patients in northern New England who underwent isolated CABG surgery between 2001 and 2005. Based on National Kidney Foundation definitions, moderate renal insufficiency was defined as a GFR <60 mL/min/1.73 m2 and severe renal insufficiency as a GFR <30. Patients with at least moderate renal insufficiency at baseline were eliminated from the analysis, leaving 8363 patients who became our study cohort. A prediction model was developed to identify variables that best predicted the risk of developing severe renal insufficiency using multiple logistic regression, and the predictive ability of the model quantified using a bootstrap validated C-Index (Area Under ROC) and Hosmer-Lemeshow statistic. Three percent of the patients with normal renal function before CABG surgery developed severe renal insufficiency (229/8363). In a multivariable model the preoperative patient characteristics most strongly associated with postoperative severe renal insufficiency included: age, gender, white blood cell count >12,000, prior CABG, congestive heart failure, peripheral vascular disease, diabetes, hypertension, and preoperative intraaortic balloon pump. The predictive model was significant with chi2 150.8, probability value <0.0001. The model discriminated well, ROC 0.72 (95%CI: 0.68 to 0.75). The model was well calibrated according to the Hosmer-Lemeshow test.
We developed a robust prediction rule to assist clinicians in identifying patients with normal, or near normal, preoperative renal function who are at high risk of developing severe renal insufficiency. Physicians may be able to take steps to limit this adverse outcome and its associated increase in morbidity and mortality.
Background Increasing numbers of the very elderly are undergoing coronary artery bypass graft surgery (CABG). Short-term results have been studied, but few data are available concerning long-term ...outcomes. Methods We conducted a cohort study of 54,397 consecutive patients undergoing primary, isolated CABG surgery between July 1, 1987, and June 30, 2006. Patient records were linked to the Social Security Administration’s Death Master File. Results During 390,871 person-years of follow-up, there were 17,352 deaths. There were 51,149 patients younger than 80 years, 2,661 patients aged 80 to 84 years, and 587 patients aged 85 or more years who underwent isolated CABG surgery. Crude in-hospital survival was 97.2% for those less than 80 years, 98.3% for those aged 80 to 84 years, and 87.6% for those aged 85 or more years. Patients aged 80 or more years were more likely to be female (46.9%), more likely to be emergency priority (10.2%), and more likely to have associated comorbidities than younger patients. Patients aged 85 or more years were more likely to have intraoperative and postoperative morbid events. Among patients younger than 80, median survival was 14.4 years with an annual incidence of death of 4.2%. Among patients 80 to 84 years old, median survival time was 7.4 years, with an annual incidence rate of death of 10.3%. Among patients aged 85 or more years, median survival was 5.8 years, and the annual incidence of death was 13.7%. Conclusions Although very elderly CABG patients have more comorbidities and more acute presentation than younger patients and their in-hospital mortality rate is high, their long-term survival is surprisingly good.
Increasing numbers of the very elderly are undergoing aortic valve procedures. We describe the short- and long-term survivorship for this cohort.
We conducted a cohort study of 7584 consecutive ...patients undergoing open aortic valve surgery without (51.1%; AVR) or with (48.9%; AVR + CABG) concomitant coronary artery bypass graft surgery between November 10, 1987 through June 30, 2006. Patient records were linked to the Social Security Administration's Death Master File. Survivorship was stratified by age and concomitant CABG surgery. During 39 835 person-years of follow-up, there were 2877 deaths. Among AVR, there were 3304 patients <80 years of age, 419 patients 80 to 84 years, and 156 patients > or =85 years (24 patients >90 years). Among AVR+CABG patients, there were 2890 patients <80 years of age, 577 patients 80 to 84 years, and 238 patients > or =85 years (22 patients >90 years). Median survivorship for patients undergoing isolated AVR was 11.5 years (<80 years), 6.8 years (80 to 84 years), 6.2 years (> or =85 years); for patients undergoing AVR+CABG, median survivorship was 9.4 years (<80 years), 6.8 years (80 to 84 years), and 7.1 years (> or =85 years). Among both procedures, adjusted survivorship was significantly different across strata of age (P<0.001). These findings are similar to life expectancy of the general population from actuarial tables: 80 to 84 years (7 years) and > or =85 years (5 years).
Survivorship among octogenarians is favorable, with more than half the patients surviving more than 6 years after their surgery. Concomitant CABG surgery does not diminish median survivorship among patients >80 years of age.
The chordal structure is a part of mitral valve geometry that has been commonly neglected or simplified in computational modeling due to its complexity. However, these simplifications cannot be used ...when investigating the roles of individual chordae tendineae in mitral valve closure. For the first time, advancements in imaging, computational techniques, and hardware technology make it possible to create models of the mitral valve without simplifications to its complex geometry, and to quickly run validated computer simulations that more realistically capture its function. Such simulations can then be used for a detailed analysis of chordae-related diseases. In this work, a comprehensive model of a subject-specific mitral valve with detailed chordal structure is used to analyze the distinct role played by individual chordae in closure of the mitral valve leaflets. Mitral closure was simulated for 51 possible chordal rupture points. Resultant regurgitant orifice area and strain change in the chordae at the papillary muscle tips were then calculated to examine the role of each ruptured chorda in the mitral valve closure. For certain subclassifications of chordae, regurgitant orifice area was found to trend positively with ruptured chordal diameter, and strain changes correlated negatively with regurgitant orifice area. Further advancements in clinical imaging modalities, coupled with the next generation of computational techniques will enable more physiologically realistic simulations.
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