Early Midterm Results After Valve Replacement With Contemporary Pericardial Prostheses for Severe Aortic Stenosis.

BACKGROUND: Clinical studies have demonstrated improved gradients after aortic valve replacement with the Trifecta (TR) valve (Abbott Cardiovascular, St Paul, MN) as compared with the Carpentier-Edwards Magna Ease (ME) valve (Edwards Lifesciences, Irvine, CA). Clinical benefits of this strategy have not been demonstrated. METHODS: Patients undergoing aortic valve replacement for severe aortic stenosis with either valve were included. Patients were excluded if they underwent concomitant procedures other than coronary artery bypass grafting. Inverse proportion treatment weighting was used in the analysis. The primary outcome was a composite of cardiac mortality, need for reintervention, and freedom from first congestive heart failure (CHF). Secondary outcomes were all-cause mortality, the composite components, and cumulative CHF admission. Follow-up echocardiograms were assessed in a cohort of patients to assess structural valve degeneration. RESULTS: There were 331 patients in the TR group and 360 patients in the ME group. The TR group had more women (48% vs 32%, P < .001) with smaller roots (left ventricular outflow tract diameter: TR, 2.11 cm; ME, 2.17 cm; P < .001). After weighting there was no significant difference in the composite measure between groups (P > .05). There was no difference in all-cause mortality (hazard ratio, 0.82; 95% confidence interval, 0.42-1.59; P = .56), and 5-year survival was 91.9% in the ME group and 93.4% in the TR group. There was no difference in cardiac death, reintervention, or first onset of CHF or incidence of structural valve degeneration between groups. There was no difference in the rate of admissions for CHF per 100 patients between the 2 valve types (P = .19). CONCLUSIONS: Early hemodynamic benefits have not translated into differences in medium-term clinical outcomes between these 2 valves. Long-term follow-up is necessary.

Defining an Intraoperative Hypotension Threshold in Association with De Novo Renal Replacement Therapy after Cardiac Surgery.

BACKGROUND: Acute kidney injury (AKI) is a frequent and deadly complication after cardiac surgery. In the absence of effective therapies, a focus on risk factor identification and modification has been the mainstay of management. The authors sought to determine the impact of intraoperative hypotension on de novo postoperative renal replacement therapy in patients undergoing cardiac surgery, hypothesizing that prolonged periods of hypotension during and after cardiopulmonary bypass (CPB) were associated with an increased risk of renal replacement therapy. METHODS: Included in this single-center retrospective cohort study were adult patients who underwent cardiac surgery requiring CPB between November 2009 and April 2015. Excluded were patients who were dialysis dependent, underwent thoracic aorta or off-pump procedures, or died before receiving renal replacement therapy. Degrees of hypotension were defined by mean arterial pressure (MAP) as less than 55, 55 to 64, and 65 to 74 mmHg before, during, and after CPB. The primary outcome was de novo renal replacement therapy. RESULTS: Of 6,523 patient records, 336 (5.2%) required new postoperative renal replacement therapy. Each 10-min epoch of MAP less than 55 mmHg post-CPB was associated with an adjusted odds ratio of 1.13 (95% CI, 1.05 to 1.23; P = 0.002), and each 10-min epoch of MAP between 55 and 64 mmHg post-CPB was associated with an adjusted odds ratio of 1.12 (95% CI, 1.06 to 1.18; P = 0.0001) for renal replacement therapy. The authors did not observe an association between hypotension before and during CPB with renal replacement therapy. CONCLUSIONS: MAP less than 65 mmHg for 10 min or more post-CPB is associated with an increased risk of de novo postoperative renal replacement therapy. The association between intraoperative hypotension and AKI was weaker in comparison to factors such as renal insufficiency, heart failure, obesity, anemia, complex or emergent surgery, and new-onset postoperative atrial fibrillation. Nonetheless, post-CPB hypotension is a potentially easier modifiable risk factor that warrants further investigation.

Development of a median sternotomy simulation model for cardiac surgery training.

OBJECTIVE: We sought to develop a simulation model to train resident physicians in the performance of a median sternotomy. METHODS: A modified Delphi consensus process was used with cardiac surgery staff to develop a 20-point checklist for the safe performance of a median sternotomy. Thirteen junior cardiac surgery trainees from across Canada participated in this study to assess the simulation model. Trainees performed the sternotomy before and after reviewing an instructional video. Two senior cardiac surgery resident physicians assessed the participants with the checklist during each session. An entry and exit questionnaire was given to the participants to evaluate the simulation model. RESULTS: Participants scored higher after the training (14.3 ± 2.0) compared with before training (8.0 ± 3.1) (P < .001). The mean duration of time for participants to complete the sternotomy was shorter before training (188 ± 52 seconds vs 228 ± 58 seconds; P = .003). The checklist interrater reliability was κ = 0.47 (moderate) for before training and κ = 0.37 (fair) for after training. All study participants rated the simulation sessions as very useful or extremely useful. CONCLUSIONS: Using the simulation model, training video, and checklist, trainees were able to improve their skill in performing a median sternotomy. This improvement was associated with longer times to complete all procedure steps. Rater training may further improve interrater reliability. Our median sternotomy checklist and simulation model can be adopted for the technical skills training of future cardiac surgery trainees.

Left ventricular function recovery after revascularization: comparative effects of percutaneous coronary intervention and coronary artery bypass grafting.

PURPOSE OF REVIEW: In 2013, heart failure with recovered ejection fraction (HFrecEF) was introduced as a new heart failure phenotype. This review provides an overview of HFrecEF and the comparative effects of percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG) on left ventricular ejection fraction (LVEF) recovery in patients with ischemic cardiomyopathy. RECENT FINDINGS: There has been emerging data indicating that LV functional recovery is possible and HFrecEF is associated with improved survival and better quality of life. CABG may be associated with larger improvement in LVEF when compared with PCI. However, there is significant paucity of studies, which directly compare the impact of PCI and CABG on LVEF recovery in the setting of ischemic cardiomyopathy. SUMMARY: LVEF recovery is emerging as an important outcome with demonstrated survival and quality-of-life benefits. Future randomized clinical trials comparing the impact of contemporary PCI and CABG on LVEF recovery are needed in patients with ischemic cardiomyopathy.

Pivotal contemporary trials of percutaneous coronary intervention vs. coronary artery bypass grafting: a surgical perspective.

Coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI) are the two revascularization strategies for patients with coronary artery disease (CAD). While CABG continues to be the gold standard for revascularization, advancements in PCI technology have triggered numerous, often industry-funded investigations to challenge this role. This perspective will provide a summary of previous RCTs comparing CABG vs. PCI. The recently published NOBLE and EXCEL trials will be discussed in depth. Future directions of research pertaining to CABG vs. PCI will be briefly discussed in this document.

GATA6 Regulates Aortic Valve Remodeling, and Its Haploinsufficiency Leads to Right-Left Type Bicuspid Aortic Valve.

BACKGROUND: Bicuspid aortic valve (BAV), the most common congenital heart defect affecting 1% to 2% of the population, is a major risk factor for premature aortic valve disease and accounts for the majority of valve replacement. The genetic basis and mechanisms of BAV etiology and pathogenesis remain largely undefined. METHODS: Cardiac structure and function was assessed in mice lacking a Gata6 allele. Human GATA6 gene variants were analyzed in 452 BAV cases from the BAV consortium and 1849 controls from the Framingham GWAS (Genome Wide Association Study). GATA6 expression was determined in mice and human tissues using quantitative real-time polymerase chain reaction and immunohistochemistry. Mechanistic studies were carried out in cultured cells. RESULTS: Gata6 heterozygous mice have highly penetrant right-left (RL)-type BAV, the most frequent type in humans. GATA6 transcript levels are lower in human BAV compared with normal tricuspid valves. Mechanistically, Gata6 haploinsufficiency disrupts valve remodeling and extracellular matrix composition through dysregulation of important signaling molecules, including matrix metalloproteinase 9. Cell-specific inactivation of Gata6 reveals an essential role for GATA6 in secondary heart field myocytes because loss of 1 Gata6 allele from Isl- 1-positive cells-but not from endothelial or neural crest cells-recapitulates the phenotype of Gata6 heterozygous mice. CONCLUSIONS: The data identify a new cellular and molecular mechanism underlying BAV. The availability of an animal model for the most frequent human BAV opens the way for the elucidation of BAV pathogenesis and the development of much needed therapies.

Coronary Surgery in Women and the Challenges We Face.

This review was undertaken to understand the dynamics that have shaped our current treatment of women who undergo coronary artery bypass grafting (CABG) and summarize the current literature on surgical revascularization in women. There has been improved access to CABG over the past several decades. Despite this, compared with men, CABG in women involves fewer grafts and less frequent use of arterial grafts, the latter having improved long-term patency compared with saphenous vein grafts. We attempt to determine whether the adverse clinical profile of women, when referred for CABG is responsible for this finding. Female coronary anatomy and pathophysiology are reviewed and an attempt is made to understand how this might affect decisions of selection and outcome measures post CABG. We review the short-term, long-term, and quality of life outcomes in women. These data are taken from large databases, as well as from more recent publications. Randomized controlled trial data and meta-analytic data are used when available. Differential use of and outcomes of surgical strategies, including off-pump CABG and total arterial revascularization, are contrasted with those in men. This review shows that there continues to be widespread differences in surgical approach to coronary artery disease in female vs male patients. We provide evidence suggestive of the existence of issues specific to women that affect selection for surgical procedures and outcomes in women. More work is required to understand the reason for these differences and how to optimize sex-specific outcomes.

The balance between short-term and long-term outcomes of bilateral internal thoracic artery skeletonization in coronary artery bypass surgery: a propensity-matched cohort study.

OBJECTIVES: There is growing interest in the use of bilateral internal thoracic arteries (BITAs) for myocardial revascularization. This study sought to compare the balance between early benefits and long-term outcomes of skeletonized or non-skeletonized conduits and to determine whether differences in outcomes are affected by other patient risk factors. METHODS: BITAs were used in 1504 cases with either SK or NSK conduits. Propensity matching was completed using 22 covariates identifying 441 pairs of patients. The primary outcomes are the sternal wound infection in the short term and the composite outcome of all-cause mortality, myocardial infarction, revascularization and congestive heart failure. Outcomes were assessed using paired analysis techniques and Cox proportional hazards regression models stratified using the matched pairs. RESULTS: Incidences of in-hospital mortality and perioperative myocardial infarction were similar in both groups. There were fewer sternal wound infections in the SK group (5.4 vs 9.1%, P = 0.033). Homogeneity testing of the relative risk estimates confirmed that there was a protective effect of skeletonization in men that was not demonstrated in women (P = 0.020). SK had a protective effect in diabetics not seen in non-diabetics (P = 0.048). The composite outcome of all-cause mortality, myocardial infarction, revascularization and congestive heart failure at a median of 5.6 years was comparable in both groups (hazard ratio 0.81, 95% confidence interval 0.57-1.15). CONCLUSION: Skeletonization results in better perioperative outcomes and comparable cardiac outcomes in patients undergoing BITA with the greatest benefit in men and patients with chronic obstructive pulmonary disease.

Simulation-Based Skill Training for Trainees in Cardiac Surgery: A Systematic Review.

BACKGROUND: Simulation-based training has been an important part of the solution to address the shortfalls in cardiac surgery training. This review was conducted to identify and systematically summarize existing evidence on outcomes and methodological quality of simulation-based skills training for cardiac surgery trainees. METHODS: MEDLINE, Embase, and ERIC (Education Resources Information Center) databases were searched. Studies included peer-reviewed publications with simulation-based skill training in cardiac surgery programs with outcome measures of performance. Data extraction covered the type of skills training, simulator type and fidelity, the level of trainees, assessment tools, assessors, study design and its components, strengths and limitations, and elements required for the Medical Education Research Study Quality Instrument score. The review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. RESULTS: Of 16 studies that met the criteria, only four (25%) randomized controlled trials were identified, and the remaining were observational studies. Seven observational studies (43.7%) were single-group pre-post tests. The mean number of trainees was 20.4 (SD, 14.1). Low-fidelity simulators were used in 13 studies (81.2%). Most of the studies (81.3%) were high quality based on a Medical Education Research Study Quality Instrument score of 12 or more. Evidence of assessment tool validation was absent among all studies. No study outcome measures were directed to skills transfer to the operating room or patient outcomes. Overall learning outcomes' effect sizes were consistently high (2.2; SD, 1.6), with junior residents benefitting most (effect size, 2.8; SD, 2.2) CONCLUSIONS: Simulation-based skill training is associated with improved learning outcomes for cardiac surgery trainees with large effect sizes, but more behavior-level outcomes are required to fully assess its value.

Development of a high fidelity pressurized porcine beating heart simulator for cardiac surgery training.

BACKGROUND: Development of a high-fidelity cardiac surgery simulator (CSS) requires integration of a heart model with a mock cardiopulmonary bypass (CPB) circuit that can provide feedback to mimic the pathophysiology of cardiac surgery. However, the cost of commercially available simulators precludes regular use. We describe steps in the construction of a high-fidelity CSS that integrates a pulsatile paracorporeal ventricular-assist device (Pulse-VAD) and a commercially available CPB simulator. METHODS/RESULTS: Eight porcine hearts were initially prepared. The configuration consisted of cannulation of the distal descending aorta and the inferior vena cava to enable pressurization of the heart after connection to the Califia® simulator, as well as Pulse-VAD cannulation (fitted with inflatable balloons) of both ventricles. After each simulation run, the team addressed key issues to derive successive model changes through consensus. Key modifications included: a) pressure maintenance of the cardiac chambers (removal of lungs, Pulse-VAD cannulation sites at the left pulmonary artery and vein, double ligation of arch vessels); b) high-fidelity beating of both ventricles (full Pulse-VAD bladder filling and ensuring balloon neck placement at the valvular plane) and c) reproducible management of porcine anatomy (management of porcine aorta, ligation of left azygous vein and shortened ascending thoracic aortic segment). CONCLUSION: A CSS can be prepared at low cost, with integration into a high-fidelity CPB simulator with a novel beating heart component. This setup can be used in teaching the basics of CPB techniques and complex surgical procedures. Future work is needed to validate this model as a simulation instrument.

Planar biaxial testing of heart valve cusp replacement biomaterials: Experiments, theory and material constants.

OBJECTIVES: Aortic valve (AV) repair has become an attractive option to correct aortic insufficiency. Yet, cusp reconstruction with various cusp replacement materials has been associated with greater long-term repair failures, and it is still unknown how such materials mechanically compare with native leaflets. We used planar biaxial testing to characterize six clinically relevant cusp replacement materials, along with native porcine AV leaflets, to ascertain which materials would be best suited for valve repair. METHODS: We tested at least six samples of: 1) fresh autologous porcine pericardium (APP), 2) glutaraldehyde fixed porcine pericardium (GPP), 3) St Jude Medical pericardial patch (SJM), 4) CardioCel patch (CC), 5) PeriGuard (PG), 6) Supple PeriGuard (SPG) and 7) fresh porcine AV leaflets (PC). We introduced efficient displacement-controlled testing protocols and processing, as well as advanced convexity requirements on the strain energy functions used to describe the mechanical response of the materials under loading. RESULTS: The proposed experimental and data processing pipeline allowed for a robust in-plane characterization of all the materials tested, with constants determined for two Fung-like hyperelastic, anisotropic strain energy models. CONCLUSIONS: Overall, CC and SPG (respectively PG) patches ranked as the closest mechanical equivalents to young (respectively aged) AV leaflets. Because the native leaflets as well as CC, PG and SPG patches exhibit significant anisotropic behaviors, it is suggested that the fiber and cross-fiber directions of these replacement biomaterials be matched with those of the host AV leaflets. STATEMENT OF SIGNIFICANCE: The long-term performance of cusp replacement materials would ideally be evaluated in large animal models for AV disease and cusp repair, and over several months or more. Given the unavailability and impracticality of such models, detailed information on stress-strain behavior, as studied herein, and investigations of durability and valve dynamics will be the best surrogates, as they have been for prosthetic valves. Overall, comparison with Fig. 3 suggests that CC and SPG (respectively PG) patches may be the closest mechanical equivalents to young (respectively aged) AV leaflets. Interestingly, the thicknesses of these materials are close to those reported for porcine and younger human AV leaflets, which may facilitate surgical implantation, by contrast to the thinner APP which has poor handling qualities. Because the native leaflets as well as CC, PG and SPG patches exhibit anisotropic behaviors, from a mechanistic perspective alone, it stands to reason that cardiac surgeons should seek to intraoperatively match the fiber and cross-fiber directions of these replacement biomaterials with those of the repaired AV leaflets.