Waitlist Mortality and Extracorporeal Membrane Oxygenation Bridge to Lung Transplant.

BACKGROUND: Use of extracorporeal membrane oxygenation (ECMO) as bridge to lung transplant has increased. However, little is known about patients placed on ECMO who die while on the waiting list. Using a national lung transplant data set, we investigated variables associated with waitlist mortality of patients bridged to lung transplant. METHODS: All patients supported on ECMO at time of listing were identified using the United Network for Organ Sharing database. Univariable analyses were performed using bias-reduced logistic regression. Cause-specific hazard models were used to determine the effect of variables of interest on hazard of outcomes. RESULTS: From April 2016 to December 2021, 634 patients met inclusion criteria. Of these, 445 (70%) were successfully bridged to transplant, 148 (23%) died on the waitlist, and 41 (6.5%) were removed for other reasons. Univariable analysis found associations between waitlist mortality and blood group, age, body mass index, serum creatinine, lung allocation score, days on waitlist, United Network for Organ Sharing region, and being listed at a lower-volume center. Cause-specific hazard models demonstrated that patients at high-volume centers were 24% more likely to survive to transplant and 44% less likely to die on the waitlist. Among patients who were successfully bridged to transplant, there was no difference in survival between low- and high-volume centers. CONCLUSIONS: ECMO is an appropriate strategy to bridge selected high-risk patients to lung transplant. Of those placed on ECMO with intent to transplant, about one quarter may not survive to transplantation. High-risk patients requiring advanced support strategies may be more likely to survive to transplant when bridged at a high-volume center.

The predictive capability of aortic stiffness index for aortic dissection among dilated ascending aortas.

OBJECTIVE: We created a finite element model to predict the probability of dissection based on imaging-derived aortic stiffness and investigated the link between stiffness and wall tensile stress using our model. METHODS: Transthoracic echocardiogram measurements were used to calculate aortic diameter change over the cardiac cycle. Aortic stiffness index was subsequently calculated based on diameter change and blood pressure. A series of logistic models were developed to predict the binary outcome of aortic dissection using 1 or more series of predictor parameters such as aortic stiffness index or patient characteristics. Finite element analysis was performed on a subset of diameter-matched patients exhibiting patient-specific material properties. RESULTS: Transthoracic echocardiogram scans of patients with type A aortic dissection (n = 22) exhibited elevated baseline aortic stiffness index when compared with aneurysmal patients' scans with tricuspid aortic valve (n = 83, P < .001) and bicuspid aortic valve (n = 80, P < .001). Aortic stiffness index proved an excellent discriminator for a future dissection event (area under the curve, 0.9337, odds ratio, 2.896). From the parametric finite element study, we found a correlation between peak longitudinal wall tensile stress and stiffness index (ρ = .6268, P < .001, n = 28 pooled). CONCLUSIONS: Noninvasive transthoracic echocardiogram-derived aortic stiffness measurements may serve as an impactful metric toward predicting aortic dissection or quantifying dissection risk. A correlation between longitudinal stress and stiffness establishes an evidence-based link between a noninvasive stiffness parameter and stress state of the aorta with clinically apparent dissection events.

Giant coronary artery aneurysm masquerading as an anterior mediastinal mass.

Coronary artery aneurysms are exceedingly rare and tend to be found incidentally on angiography. We present the case of a 6 cm giant coronary artery aneurysm discovered in a 25 year old man. Subsequent workup included cardiac-gated MRI, CT angiography, and left heart catheterization. Imaging revealed a 6.7 × 6.2 × 6.0 cm aneurysm involving the mid LAD subsequent to the takeoff of a large septal perforator. The patient was taken electively for operative repair during which the aneurysm was opened, unroofed, and ligated at the ostium while taking care to ensuring normal flow in the septal perforator that supplied multiple small collaterals. In this unique case, a coronary artery aneurysm of considerable size was encountered in the LAD of a healthy young adult in which the size of the aneurysm precluded distal revascularization via bypass grafting. Multiple imaging modalities were used to characterize this finding and aid in surgical planning.

Common deletion variants causing protocadherin-α deficiency contribute to the complex genetics of BAV and left-sided congenital heart disease.

Bicuspid aortic valve (BAV) with ~1%-2% prevalence is the most common congenital heart defect (CHD). It frequently results in valve disease and aorta dilation and is a major cause of adult cardiac surgery. BAV is genetically linked to rare left-heart obstructions (left ventricular outflow tract obstructions [LVOTOs]), including hypoplastic left heart syndrome (HLHS) and coarctation of the aorta (CoA). Mouse and human studies indicate LVOTO is genetically heterogeneous with a complex genetic etiology. Homozygous mutation in the Pcdha protocadherin gene cluster in mice can cause BAV, and also HLHS and other LVOTO phenotypes when accompanied by a second mutation. Here we show two common deletion copy number variants (delCNVs) within the PCDHA gene cluster are associated with LVOTO. Analysis of 1,218 white individuals with LVOTO versus 463 disease-free local control individuals yielded odds ratios (ORs) at 1.47 (95% confidence interval [CI], 1.13-1.92; p = 4.2 × 10-3) for LVOTO, 1.47 (95% CI, 1.10-1.97; p = 0.01) for BAV, 6.13 (95% CI, 2.75-13.7; p = 9.7 × 10-6) for CoA, and 1.49 (95% CI, 1.07-2.08; p = 0.019) for HLHS. Increased OR was observed for all LVOTO phenotypes in homozygous or compound heterozygous PCDHA delCNV genotype comparison versus wild type. Analysis of an independent white cohort (381 affected individuals, 1,352 control individuals) replicated the PCDHA delCNV association with LVOTO. Generalizability of these findings is suggested by similar observations in Black and Chinese individuals with LVOTO. Analysis of Pcdha mutant mice showed reduced PCDHA expression at regions of cell-cell contact in aortic smooth muscle and cushion mesenchyme, suggesting potential mechanisms for BAV pathogenesis and aortopathy. Together, these findings indicate common variants causing PCDHA deficiency play a significant role in the genetic etiology of common and rare LVOTO-CHD.

Predissection-derived geometric and distensibility indices reveal increased peak longitudinal stress and stiffness in patients sustaining acute type A aortic dissection: Implications for predicting dissection.

OBJECTIVE: To assess ascending aortic distensibility and build geometry and distensibility-based patient-specific stress distribution maps in patients sustaining type A aortic dissection (TAAD) using predissection noninvasive imaging. METHODS: Review of charts from patients undergoing surgical repair of TAAD (n = 351) led to the selection of a subset population (n = 7) with 2 or more predissection computed tomography angiography scans and echocardiograms at least 1 year before dissection. Ascending aortic wall biomechanical properties (aortic strain, distensibility, and stiffness) were compared with age- and size-matched nondissected nonaneurysmal controls. Patient-specific aortic strain served as an input in aortic geometry-based simulated 3-dimensional reconstructions to generate longitudinal and circumferential wall stress maps. Inspection of perioperative dissection scans and intraoperative visual examination confirmed primary tear locations. RESULTS: Predissection echocardiography revealed ascending aortas of patients sustaining TAAD to exhibit decreased aortic wall strain (14.50 ± 1.13% vs 8.49 ± 1.08%; P < .01), decreased distensibility (4.26 ± 0.44 vs 2.39 ± 0.33 10-6 cm2·dyne-1; P < .01), increased stiffness (3.84 ± 0.24 vs 7.48 ± 1.05; P < .001), and increased longitudinal wall stress (246 ± 22 vs 172 ± 37 kPa; P < .01). There was no significant difference in circumferential wall stress. Predissection computed tomography angiography models revealed overlap between regions of increased longitudinal wall stress and primary tear sites. CONCLUSIONS: Using predissection imaging, we identified increased stiffness and longitudinal wall stress in ascending aortas of patients with dissection. Patient-specific imaging-derived biomechanical property maps like these may be instrumental toward designing better prediction models of aortic dissection potential.