Midterm Results of an Algorithmic 3-Pronged Approach to Bicuspid Aortic Valve Repair

BACKGROUND

This study evaluated midterm outcomes of a 3-pronged algorithm for bicuspid aortic valve (BAV) repair. Valve-sparing root reimplantation (VSRR) was performed for patients with aortic root dilatation. In those without a root aneurysm, external subannular ring (ESAR) was performed for annuli ≥28 mm and subcommissural annuloplasty (SCA) for annuli <28 mm.

METHODS

This was a retrospective review of prospectively collected data of 242 patients undergoing primary BAV repair from April 29, 2004, to March 1, 2023, at a single institution. Primary end points were mortality, structural valve degeneration (SVD), which was defined as a composite of more than moderate aortic insufficiency or severe aortic stenosis, and reintervention.

RESULTS

The algorithm was used to treat 201 patients; of these, 130 underwent VSRR, 35 had ESAR, and 36 underwent SCA. Most were men with mean age of 43.8 years (SD, 12.0 years), which was similar between groups. Preoperative aortic insufficiency more than moderate was more common for ESAR compared with VSRR and SCA (74.3% vs 37.7% vs 44.4%, P < .001). At 30 days, mortality was 0.8% (n = 1) for VSRR and 0% for ESAR and SCA. At 6 years, overall Kaplan-Meier survival was 98.9% (95% CI, 97.3%-100%), with no differences between groups (P = .5). The cumulative incidence of SVD was 4.7% (95% CI, 0.1%-9.2%) for VSRR, 6.4% (95% CI, 0%-14.6%) for ESAR, and 0% for SCA (P = .4). Similarly, the cumulative incidence of reintervention with all-cause mortality as a competing risk was 2.2% (95% CI, 0.4%-6.9%), 6.1% (95% CI, 1%-17.9%), and 0% for VSRR, ESAR, and SCA, respectively (P = .506).

CONCLUSIONS

A 3-pronged algorithmic approach to BAV repair results in excellent survival and freedom from reoperation at 6 years.

The impact of reoperative surgery on aortic root replacement in the United States

OBJECTIVE

Reoperative sternotomy is associated with poor outcomes after cardiac surgery. We aimed to investigate the impact of reoperative sternotomy on the outcomes after aortic root replacement.

METHODS

All patients who underwent aortic root replacement from January 2011 to June 2020 were identified using the Society of Thoracic Surgeons Adult Cardiac Surgery Database. We compared outcomes between patients who underwent first-time aortic root replacement with those with a history of sternotomy undergoing reoperative sternotomy aortic root replacement using propensity score matching. Subgroup analysis was performed among the reoperative sternotomy aortic root replacement group.

RESULTS

A total of 56,447 patients underwent aortic root replacement. Among them, 14,935 (26.5%) underwent reoperative sternotomy aortic root replacement. The annual incidence of reoperative sternotomy aortic root replacement increased from 542 in 2011 to 2300 in 2019. Aneurysm and dissection were more frequently observed in the first-time aortic root replacement group, whereas infective endocarditis was more common in the reoperative sternotomy aortic root replacement group. Propensity score matching yielded 9568 pairs in each group. Cardiopulmonary bypass time was longer in the reoperative sternotomy aortic root replacement group (215 vs 179 minutes, standardized mean difference = 0.43). Operative mortality was higher in the reoperative sternotomy aortic root replacement group (10.8% vs 6.2%, standardized mean difference = 0.17). In the subgroup analysis, logistic regression demonstrated that individual patient repetition of (second or more resternotomy) surgery and annual institutional volume of aortic root replacement were independently associated with operative mortality.

CONCLUSIONS

The incidence of reoperative sternotomy aortic root replacement might have increased over time. Reoperative sternotomy is a significant risk factor for morbidity and mortality in aortic root replacement. Referral to high-volume aortic centers should be considered in patients undergoing reoperative sternotomy aortic root replacement.

Validation of the GERAADA score to predict 30-day mortality in acute type A aortic dissection in a single high-volume aortic centre

OBJECTIVES

This study aimed to evaluate employing the German Registry of Acute Aortic Dissection Type A (GERAADA) score to predict 30-day mortality in an aortic centre in the USA.

METHODS

Between January 2010 and June 2021, 689 consecutive patients underwent surgery for acute type A dissection at a single institution. Excluded were patients with missing clinical data (N = 4). The GERAADA risk score was retrospectively calculated via a web-based application. Model discrimination power was calculated with c-statistics from logistic regression and reported as the area under the receiver operating characteristic curve with 95% confidence intervals. The calibration was measured by calculating the observed versus estimated mortality ratio. The Brier score was used for the overall model evaluation.

RESULTS

Included were 685 patients [mean age 60.6 years (SD: 13.5), 64.8% male] who underwent surgery for acute type A aortic dissection. The 30-day mortality rate was 12.0%. The GERAADA score demonstrated very good discrimination power with an area under the receiver operating characteristic curve of 0.762 (95% confidence interval 0.703-0.821). The entire cohort's observed versus estimated mortality ratio was 0.543 (0.439-0.648), indicating an overestimation of the model-calculated risk. The Brier score was 0.010, thus revealing the model's acceptable overall performance.

CONCLUSIONS

The GERAADA score is a practical and easily accessible tool for reliably estimating the 30-day mortality risk of patients undergoing surgery for acute type A aortic dissection. This model may naturally overestimate risk in patients undergoing surgery in experienced aortic centres.

Intracannula Thrombus Formation Associated With Dual Lumen ProtekDuo Cannula in Extracorporeal Membrane Oxygenation (ECMO)

Extracorporeal membrane oxygenation (ECMO) is used in cases of severe respiratory failure refractory to medical management. Use of ECMO is increasing, along with new cannulation strategies including oxygenated right ventricular assist devices (oxy-RVADs). Multiple dual lumen cannulas are now available, which increase the potential for patient mobility and decrease the number of vascular access sites. However, dual lumen, single cannula flow can be limited by adequate inflow, requiring the need for an additional inflow cannula to meet patient demands. This cannula configuration may result in differential flows in the inflow and outflow limbs and altered flow dynamics, increasing the risk of intracannula thrombus. We describe a series of four patients treated with oxy-RVAD for COVID-19-associated respiratory failure complicated by dual lumen ProtekDuo intracannula thrombus.

The Penn Classification System For Malperfusion In Acute Type A Dissection: A 25 Year Experience

BACKGROUND

The University of Pennsylvania classification system (Penn class) of acute type A aortic dissection (aTAAD) is used to evaluate the impact of malperfusion on surgical outcomes. The purpose of this analysis was to determine the validity of Penn class in a larger and more contemporary cohort and to compare its performance with other classification systems.

METHODS

This was a retrospective study of patients who underwent aTAAD repair at our institution from 1993 to 2020. Patients were assigned to Penn class on the basis of burden of preoperative malperfusion syndrome. The association of Penn class and 30-day mortality was evaluated by multivariable regression. The discriminatory ability of Penn class for mortality was determined by a bootstrapped C statistic.

RESULTS

There were 1192 patients, of whom 50% were assigned to Penn class A (no ischemia), 21% (253/1192) to class B (local ischemia), 14% (171/1192) to class C (generalized ischemia), and 14% (167/1192) to class B-C (combined ischemia). The incidence of mortality rose significantly with increasing Penn class from 5% (31/601) in class A to 35% (59/167) in class B-C (P < .001). After adjustment, 30-day mortality increased significantly with class B (odds ratio [OR], 2.43; 95% CI, 1.38-4.27), class C (OR, 3.39; 95% CI, 1.90-6.03), and class B-C (OR, 13.08; 95% CI, 7.90-22.15) compared with class A. The C statistic was 0.77 (95% CI, 0.72-0.80) and was significantly higher than for models featuring alternative classification systems (P < .05).

CONCLUSIONS

Penn class provides excellent discrimination for 30-day mortality after repair of aTAAD.

National Adherence to Medical Management of Aortic Aneurysms

OBJECTIVES

The purpose of this study was to describe levels of adherence to guideline-based medical management in patients with aortic aneurysms, using an analogous population with coronary artery disease as a comparator. Adherence among those with aortic aneurysms has never been studied.

METHODS

Adult patients with an aortic aneurysm or coronary artery disease diagnosed between 2004 and 2018 in the Optum Clinformatics deidentified Datamart were queried. Aneurysms were subclassified as thoracic, abdominal, or both. Receipt of an antihypertensive or antihyperlipidemic was determined through pharmacy claims. Adherence was determined as receipt of the indicated pharmacologic(s) after a diagnosis of aneurysm or coronary artery disease. Adherence was compared between those with aneurysms and coronary disease using univariable logistic regression.

RESULTS

After exclusions, 194,144 patients with an aortic aneurysm and 3,946,782 with coronary artery disease were identified. Overall adherence was low (45.0%) and differed significantly by aneurysm subtype: highest in isolated thoracic (45.9%) and lowest in isolated abdominal aneurysms (42.6%). Adherence levels declined significantly after 1 year by about 15% in each aneurysm subtype. All subtypes of aneurysm had a significantly lower odds of adherence compared to those with coronary disease with odds ranging from 0.61 in those with isolated abdominal aneurysms to 0.80 with isolated thoracic aneurysms.

CONCLUSIONS

Adherence among those with aortic aneurysms is very low, differs by subtype, and declines with time. Levels of adherence in those with aortic aneurysms is significantly lower compared to those with coronary artery disease. This should prove a reasonable target for implementation initiatives.

Valve-sparing Root Reimplantation In Patients With Left Ventricular Dilation

OBJECTIVES

The purpose of this study was to evaluate the association between left ventricular (LV) dilation and outcomes following valve-sparing root reimplantation.

METHODS

Patients with an indexed left ventricular internal diameter during systole (iLVIDS) of ≥ 2.0 cm/m2 were categorized as having LV dilation. Outcomes were post-operative aortic insufficiency (AI), re-intervention, and all-cause mortality. The cumulative incidence of each outcome was computed using the Kaplan-Meier estimator. Adjusted comparisons between strata were performed for each outcome using a Cox proportional-hazards model. Where possible, the competing risk of death was accounted for. Multilevel mixed-effects ordered logistic regression was performed for AI grade at follow-up.

RESULTS

There were 295 patients of whom 52 had LV dilation. Operative outcomes were excellent; there were no significant differences between groups. Patients with LV dilation demonstrated significant improvement in iLVIDS overtime. There was no association between LV dilation and post-operative AI grade >2 (HR 0.88, 95% CI 0.21 to 3.67, p = 0.89) or odds of increased AI grade overtime (OR = 0.76, 95% CI 0.30 to 1.93, p = 0.57). There were no re-interventions among those with LV dilation. Adjusted mortality was significantly higher among those with LV dilation (HR 5.56, 95% CI 1.56 to 19.9), however, deaths were unrelated to aortic valve dilation.

CONCLUSIONS

Left ventricular dilation is not associated with poorer operative outcomes, post-operative AI, or re-intervention. It is associated with increased risk of mortality, though not from valvular dysfunction. LV dilation should not deter VSRR when otherwise indicated.

The Impact of Local vs. General Anesthesia in Patients Undergoing Thoracic Endovascular Aortic Surgery

OBJECTIVE

General anesthesia is associated with inherent risks that can be avoided by the use of lesser invasive anesthetic strategies. We hypothesize that examine and compare the use of local or regional anesthesia (LRA to general anesthesia (GA) in patients undergoing thoracic endovascular aortic repair (TEVAR).

METHODS

Patients undergoing TEVAR between 2010-2020 in the Vascular Quality Initiative were analyzed. Exclusion criteria included receipt of branched or physician modified endografts and devices extending distally beyond Zone 5. Patients were categorized as receiving LRA or GA. Center volume was reported by quartile according to annualized TEVAR volume and operative outcomes were compared using appropriate frequentists tests. Univariable and multivariable regression models for anesthesia type and operative outcomes were created to compare unadjusted and adjusted rates of each outcome. Long-term survival was estimated using a Kaplan-Meier survival estimator, while adjusted survival analysis was performed using a Cox proportional-hazards model.

RESULTS

Of the 17,099 patients who underwent TEVAR, 7,299 met the inclusion and exclusion criteria. Of these, 3.8% received LRA. There were no significant differences in the annual proportion of patients who received LRA from 2011 to 2020 (p = 0.49, Chi-square test for trend). Only 18.8% of patients who received LRA were treated at the highest quartile volume centers. Patients who received LRA were older and more comorbid compared to those who received GA. There were no differences in in-hospital mortality (OR = 0.79, 95% CI 0.42 to 1.38, p = 0.44) or composite of any complication (OR = 0.79, 95% CI 0.54 to 1.14, p = 0.22) between patients who received LRA compared to GA. This also applied to patients presenting with rupture. Receipt of LRA was associated with lower odds of post-operative congestive heart failure (OR = 0.19, 95% CI 0.01 to 0.89, p = 0.01) as well as decreased length of ICU (OR = 0.54, 95% CI 0.40 to 0.72, p < 0.01) and hospital length of stay (OR = 0.64, 95% CI 0.46 to 0.84, p < 0.01). LRA was not associated with decreased long-term survival compared to GA (HR 0.95, 95% CI 0.72 to 1.25, p = 0.72).

CONCLUSION

Despite a greater number of baseline comorbidities, patients undergoing TEVAR with LRA experienced shorter ICU and post-operative lengths of stay, with similar operative outcomes and long-term survival compared to patients who received GA.. Similar findings were found amongst the rupture cohort. LRA should be considered more frequently in select patients undergoing TEVAR.

Clinical and Echocardiographic Results of Aortic Valve Replacement in the Failing Ventricle: Do Aortic Stenosis and Aortic Regurgitation Differ?

BACKGROUND

We hypothesized that long-term clinical and echocardiographic recovery of the impaired ventricle from pressure (aortic stenosis [AS]) and volume (aortic regurgitation [AR]) overload would be different after aortic valve replacement (AVR).

METHODS

We compared the results of AVR in patients with a preoperative ejection fraction (EF) of 0.35 or less due to AS, AR, or mixed disease. We constructed a mixed-effects model of EF and left ventricular (LV) end-diastolic diameter (LVEDD) to understand ventricular recovery over the short- (in-hospital), intermediate- (3-6 months), and longer- (>24 months) terms. We sought to identify factors associated with clinical and echocardiographic recovery using multivariable analysis.

RESULTS

Between July 2011 and 2017, 136 patients with a preoperative EF of 0.35 or less and severe AS (n = 83), severe AR (n = 18), or mixed AS and AR (n = 35) underwent AVR. There were 2 (1.5%) early deaths in the AS group. Survival at 1, 2, and 5 years did not differ between groups. Baseline EF did not differ between the groups but improved with markedly different trajectory and time course in the AS, AR, and mixed groups over time. LVEDD regressed in all patient cohorts, following a different pattern for AS and AR. Baseline EF and LVEDD predicted the long-term fate of the LV but did not determine survival. We identify factors associated with long-term survival.

CONCLUSIONS

The pattern of LV recovery appears to be early in AS and delayed in AR. Baseline clinical factors, rather than echocardiographic status of the LV, appear to determine late survival.

Managing acute type A aortic dissections: Is a universal approach feasible?

The goal in the treatment of acute type A aortic dissection (ATAAD) is to resect the primary intimal tear while minimizing associated complications of the disease. This goal can be accomplished by different surgical techniques and operative strategies. The extent of proximal and distal aortic reconstruction and the use of cerebral perfusion adjuncts are highly variable between institutions and within institutions themselves. As operative outcomes for ATAAD have improved considerably over the past decade, the focus has shifted towards extensive aortic reconstruction to minimize aortic reinterventions. However, there remains a distinct difference in how patients with ATAAD are managed in North America when compared with those in East Asia.

Multiorgan procurement is associated with a survival benefit after heart transplantation

We assessed the impact of donor multiorgan procurement on survival following orthotopic heart transplantation (OHT). From the UNOS STAR database, we included all adult (≥18 Y) heart transplants (OHT) performed since 2000 and used donor IDs to determine how many other organs were procured from the same donor as the recipient's heart allograft (regardless of recipient). The Kaplan-Meier survival functions and risk-adjusted Cox proportional hazards regression models were computed to assess the association of multiorgan procurement with post-heart transplantation mortality. We included 40 336 OHT patients. Including the heart, the median number of donor organs procured was 3 (IQR, 3-4). Heart donors underwent liver procurement in 89.7%; kidney(s) in 98.1% (single 95%, bilateral 5%); lung(s) in 38.0% (single 28%, bilateral 72%); pancreas in 10.4%; and intestine in 1.6%. Following risk adjustment across 16 recipient- and donor-specific variables, an increasing number of organs procured were independently associated with reduced post-OHT mortality (HR 0.98, 95% CI 0.96-0.99, P = .025). Though no significant associations were found examining specific organ types, double lung procurement trended toward a protective effect (HR 0.96, 0.92-1.01, P = .086), with counts of non-lung organs procured still bordering on significance (HR 0.97, 95% CI 0.95-1.00, P = .067). These results likely reflect improved multiorgan donor quality.

Impact of Left Ventricular Assist Device Exchange on Outcomes After Heart Transplantation

BACKGROUND

Left ventricular assist devices (LVADs) are the most common mode of circulatory support for patients awaiting heart transplantation. Unfortunately, a fraction of these patients require pump exchange during their course for pump-related adverse events. This study examined whether LVAD exchanges affect posttransplantation outcomes.

METHODS

This study focused on adult patients in the Organ Procurement and Transplantation Network database who were bridged to transplant with a LVAD implanted between 2007 and 2017. Patients who underwent LVAD exchange were compared with those supported with a single device. The primary end point was all-cause mortality at 1, 2, and 5 years after transplantation. The impact of device exchange on risk-adjusted outcomes was examined using Cox proportional hazards models.

RESULTS

Among 8239 patients who met the inclusion criteria, there were 611 pump exchanges in 560 patients (7% of recipients). The pump exchange rate was 6.24 events per 100 patient-years. Survival at 5 years was lower for those who underwent LVAD exchange (69.4% vs 77.5%, log-rank P = .027). This finding was similar for risk-adjusted 5-year mortality (hazard ratio, 1.36; 95% confidence interval, 1.11 to 1.67; P = .003). Subgroup analysis revealed lower 5-year survival for female recipients who underwent LVAD exchange (55.4% vs 79.7%, log-rank P < .001). The interaction between female sex and LVAD exchange was associated with increased risk-adjusted 5-year mortality (hazard ratio, 1.65; 95% confidence interval, 1.05 to 2.59; P = .030).

CONCLUSIONS

Recipients who underwent pump exchange while awaiting heart transplantation had a higher mortality compared with those on a primary device. Subgroup analysis revealed a marked increase in mortality of female recipients who experienced LVAD exchange.

Children's Heart Assessment Tool for Transplantation (CHAT) Score: A Novel Risk Score Predicts Survival After Pediatric Heart Transplantation

BACKGROUND

Given the shortage of donor organs in pediatric heart transplantation (HTx), pretransplant risk stratification may assist in organ allocation and recipient optimization. We sought to construct a scoring system to preoperatively stratify a patient's risk of one-year mortality after HTx.

METHODS

The United Network for Organ Sharing database was queried for pediatric (<18 years) patients undergoing HTx between 2000 and 2016. The population was randomly divided in a 4:1 fashion into derivation and validation cohorts. A multivariable logistic regression model for one-year mortality was constructed within the derivation cohort. Points were then assigned to independent predictors ( P < .05) based on relative odds ratios (ORs). Risk groups were established based on easily applicable, whole-integer score cutoffs.

RESULTS

A total of 5,700 patients underwent HTx; one-year mortality was 10.7%. There was a similar distribution of variables between derivation (n = 4,560) and validation (n = 1,140) cohorts. Of the 12 covariates included in the final model, nine were allotted point values. The low-risk (score 0-9), intermediate-risk (10-20), and high-risk (>20) groups had a 5.18%, 10%, and 28% risk of one-year mortality ( P < .001), respectively. Both intermediate-risk (OR = 2.46, 95% confidence interval [95% CI]: 1.93-3.15; P < .001) and high-risk (OR = 9.24, 95% CI: 6.92-12.35; P < .001) scores were associated with an increased risk of one-year mortality when compared to the low-risk group.

CONCLUSIONS

The Children's Heart Assessment Tool for Transplantation score represents a pediatric-specific, recipient-based system to predict one-year mortality after HTx. Its use could assist providers in identification of patients at highest risk of poor outcomes and may aid in pretransplant optimization of these children.

Size Mismatching Increases Mortality After Lung Transplantation in Preadolescent Patients

BACKGROUND

The effect of size mismatch between donor and recipient in pediatric lung transplantation (PLTx) is currently unknown. Previous studies in adults have suggested that oversized allografts are associated with improved outcomes after lung transplantation. We investigated this relationship to quantify its effect on posttransplant outcomes in children.

METHODS

The United Network of Organ Sharing database was queried for preadolescent (age <13 years) patients undergoing PLTx. Donor-to-recipient height, weight, and predictive total lung capacity (pTLC; ages 4 to 13; pTLC = 0.160 x exp[0.021 x height]) ratios were calculated. Exploratory analysis was performed to identify disjoint intervals at which survival was statistically different. Patients were categorized as well-matched, undersized, or oversized. Multivariate Cox proportional hazard regression modeling assessed the adjusted effect of mismatching on mortality. Survival analysis was performed using the Kaplan-Meier method.

RESULTS

The analysis included 540 children. One-year mortality was higher with a height mismatch of 5% or less (hazard ratio [HR], 2.97; p = 0.001) and above 5% (HR, 2.22; p = 0.009). Similarly, 1-year mortality was worse with weight mismatch of 10% or less (HR, 1.99; p = 0.035) and above 10% (HR, 2.04; p = 0.028). On unadjusted analysis, a pTLC ratio of less than 0.9 was associated with worse survival (p = 0.017). This finding persisted after multivariate risk adjustment (HR, 2.93; p = 0.02). Contrary to findings in adults, an oversized allograft (pTLC ratio > 1.1) was not associated with improved survival (HR, 1.95; p = 0.147).

CONCLUSIONS

In preadolescent children undergoing PLTx, size mismatching is associated with increased death. Our findings differ from studies in adults, which demonstrated improved survival associated with oversized allografts. Accordingly, well-matched allografts should be prioritized when assessing donor-recipient pairs for transplantation.

Surgical Closure of Patent Ductus Arteriosus in Premature Neonates Weighing Less Than 1,000 grams: Contemporary Outcomes

Objective:

The safety of surgical closure of patent ductus arteriosus (PDA) in very low birth weight premature neonates has been questioned because of associated morbidities. However, these studies are vulnerable to significant bias as surgical ligation has historically been utilized as “rescue” therapy. The objective of this study was to review our institutions’ outcomes of surgical PDA ligation.

Methods:

All neonates with operative weight of ≤1.00 kg undergoing surgical PDA ligation from 2003 to 2015 were analyzed. Records were queried to identify surgical complications, perioperative morbidity, and mortality. Outcomes included pre- and postoperative ventilator requirements, pre- and postoperative inotropic support, acute kidney injury, surgical complications, and 30-day mortality.

Results:

One hundred sixty-six preterm neonates underwent surgical ligation. One hundred twenty-one (70.3%) had failed indomethacin closure. One hundred sixty-four (98.8%) patients required mechanical ventilation prior to surgery. At 17 postoperative days, freedom from the ventilator reached 50%. Of 109 (66.4%) patients requiring prolonged preoperative inotropic support, 59 (54.1%) were liberated from inotropes by postoperative day 1. Surgical morbidity was encountered in four neonates (2.4%): two (1.2%) patients had a postoperative pneumothorax requiring tube thoracostomy, one (0.6%) patient had a recurrent laryngeal nerve injury, and one (0.6%) patient had significant intraoperative bleeding. The 30-day all-cause mortality was 1.8% (n = 3); no deaths occurred intraoperatively.

Conclusion:

In this retrospective investigation, surgical PDA closure was associated with low 30-day mortality and minimal morbidity and resulted in rapid discontinuation of inotropic support and weaning from mechanical ventilation. Given the safety of this intervention, surgical PDA ligation merits consideration in the management strategy of the preterm neonate with a PDA.

Imatinib Is Protective Against Ischemia-Reperfusion Injury in an Ex Vivo Rabbit Model of Lung Injury

BACKGROUND

Ischemia-reperfusion injury is characterized by an increase in oxidative stress and leads to significant morbidity and death. The tyrosine kinase c-Abl is activated by oxidative stress and mediates processes that affect endothelial barrier function. We hypothesized treatment with the c-Abl inhibitor imatinib would be protective against ischemia-reperfusion injury in our ex vivo rabbit model.

METHODS

Heart-lung blocs were harvested from rabbits and stored in cold in Perfadex (Vitrolife, Englewood, CO) for 18 hours. Blocs were reperfused for 2 hours in an ex vivo circuit with donor rabbit blood alone (untreated group, n = 7) or donor rabbit blood and 4 mg imatinib (treatment group, n = 10). Serial clinical variables measured every 15 minutes (arterial oxygen and carbon dioxide tension and mean pulmonary artery pressures) and biochemistry of tissue samples before and after reperfusion were assessed.

RESULTS

Compared with untreated lungs, imatinib treatment improved physiologic parameters, including oxygen, carbon dioxide, and pulmonary artery pressures. Imatinib-treated lungs had less vascular barrier dysfunction as quantified by wet-to-dry weight ratios and bronchoalveolar lavage protein concentrations. Treated lungs showed less inflammation as measured by bronchoalveolar lavage myeloperoxidase assay, less mitochondrial reactive oxygen species production, and increased antioxidant catalase levels. Finally, imatinib protected lungs from DNA damage and p53 upregulation.

CONCLUSIONS

Imatinib treatment significantly improved the physiologic performance of reperfused lungs and biochemical indicators associated with reperfusion injury in this ex vivo model. Further study is necessary to elucidate the mechanism of tyrosine kinase inhibition in lungs exposed to ischemia and reperfusion.

Impaired Renal Function Should Not Be a Barrier to Transplantation in Patients With Cystic Fibrosis

BACKGROUND

Previous studies have demonstrated an association between pretransplantation renal dysfunction (PRD) and increased mortality after lung transplantation (LT). The purpose of this study was to determine whether PRD impacts survival after LT in patients with cystic fibrosis (CF).

METHODS

We queried the United Network for Organ Sharing (UNOS) database to identify all adult (≥18 years) recipients with CF who underwent isolated LT from May 4, 2005 to December 31, 2014. We separated recipients into those with and those without PRD (glomerular filtration rate [GFR] ≤60 mL/min). We excluded patients who required dialysis before transplantation. Kaplan-Meier analysis was used to assess unadjusted survival differences. Cox proportional hazards modeling was then performed across 26 variables to assess the risk-adjusted impact of PRD on 1-, 3-, and 5-year mortality.

RESULTS

Isolated LT was performed on 1,830 patients with CF; 17 patients were excluded because of pretransplantation dialysis. Eighty-two of 1,813 patients (4.5%) had PRD (GFR ≤60 mL/min). Kaplan-Meier analysis revealed no survival differences between PRD and non-PRD groups at 1 year (85.3% versus 89.5%; log-rank p = 0.23), 3 years (71.0% versus 72.5%; p = 0.57), or 5 years (63.3% versus 59.8%; p = 0.95). After risk adjustment, PRD was not independently associated with an increased hazard for mortality at 1 year (hazard ratio [HR], 1.38 [95% confidence interval [CI], 0.74-2.58]; p = 0.31), 3 years (HR, 1.44 [95% CI, 0.92-2.24]; p = 0.11), or 5 years (HR, 1.30 [95% CI, 0.86-1.94]; p = 0.29).

CONCLUSIONS

Although PRD has historically served as a relative contraindication to LT, our study is the first to suggest that among CF recipients, PRD was not associated with increased hazard for mortality out to 5 years after LT.

Intra-Aortic Missile After Gunshot Wound to Chest: An Interesting Case of Traumatic Cardiac Injury

Missile embolus to the heart, although uncommon, is one of the most challenging scenarios in trauma. We describe a 36-year-old man who presented with a gunshot wound to the left chest and a chest x-ray revealing a foreign body in the mediastinum. A median sternotomy was performed and an injury to the left ventricle was identified. After intraoperative echocardiography and fluoroscopy confirmed a foreign body in the aortic root, cardiopulmonary bypass was implemented. A bullet was retrieved from the noncoronary sinus of the aortic valve. Injuries to the anterior leaflet of the mitral valve and left ventricle were repaired.

A Novel Risk Score to Predict the Need for Nutrition Support After Cardiac Surgery

BACKGROUND

In specific patients, early postoperative nutrition mitigates malnutrition-related morbidity and mortality. The goal of this study was to develop and validate a prediction score designed to stratify patients immediately after cardiac surgery according to risk for nutrition support (NS).

METHODS

We identified adult cardiac surgery patients at our institution in 2012 requiring postoperative NS, enteral or parenteral. Using multivariable logistic regression modeling, we developed a Johns Hopkins Hospital Nutrition Support (JHH NS) score from relative odds ratios generated by variables that independently predicted the need for NS. The JHH NS score was then prospectively validated using all patients undergoing cardiac surgery in 2015.

RESULTS

Among 1,056 patients in the derivation cohort, 87 (8%) required postoperative NS. Seven variables were identified on multivariable analysis as independent predictors of NS need and were used to create the JHH NS score. Scores ranged from 0 to 36. Each 1-point increase in the JHH NS score was associated with a 20% increase in the risk of requiring NS (odds ratio 1.20, p < 0.001). The c-statistic of the regression model for NS was 0.85. In all, 115 of 1,336 patients (8.6%) in the validation cohort required NS. Observed rates of NS in the validation group correlated positively with predicted rates (r = 0.89).

CONCLUSIONS

The JHH NS score reliably stratified patients at risk for the need for postoperative NS. This easily calculable and highly predictive screening tool may expedite timing of initiation of NS in patients at high risk for not being able to physically take in adequate nutrition.

Selective Localization of a Novel Dendrimer Nanoparticle in Myocardial Ischemia-Reperfusion Injury

BACKGROUND

Dendrimer nanoparticle therapies represent promising new approaches to drug delivery, particularly in diseases associated with inflammatory injury. However, their application has not been fully explored in models of acute myocardial ischemia (MI) and reperfusion injury.

METHODS

White male New Zealand rabbits underwent left thoracotomy with 30-minute temporary left anterior descending artery occlusion and MI confirmed by electrocardiography and histology (MI rabbits, n = 9), or left thoracotomy and pericardial opening for 30 minutes but no left anterior descending artery occlusion (control [C] rabbits, n = 9) rabbits. Following the 30-minute period, a dendrimer (generation 6 dendrimer conjugated to cyanine-5 fluorescent dye [G6-Cy5], 6.7 nm diameter) was administered intravenously and the chest closed in layers. Animals were sacrificed at 3 hours (3 MI, 3 C), 24 hours (3 MI, 3 C), or 48 hours (3 MI, 3 C) postsurgery.

RESULTS

As compared to controls, MI rabbits had twofold G6-Cy5 uptake in the myocardial anterior wall as compared to the same region in nonischemic control rabbits at 24 hours postsurgery (6.01 ± 0.57 μg/g versus 2.85 ± 0.85 μg/g; p = 0.04). This trend was also present at 48 hours (6.38 ± 1.53 μg/g versus 3.95 ± 0.60 μg/g, p = 0.21) and was qualitatively evident on confocal microscopy. G6-Cy5 half-life in serum was approximately 12 hours, with 22% of the injected G6-Cy5 dose remaining at 48 hours.

CONCLUSIONS

This study demonstrates for the first time that dendrimer nanodevices selectively localize in ischemic as compared to healthy myocardium. This indicates that dendrimer nanodevices are promising agents to deliver drugs specifically to the ischemic myocardium to attenuate the injury. Subsequent studies will assess the efficacy of a dendrimer-drug conjugate in ameliorating reperfusion injury following MI.

Simulated Regionalization of Heart and Lung Transplantation in the United States

We simulated the impact of regionalization of isolated heart and lung transplantation within United Network for Organ Sharing (UNOS) regions. Overall, 12 594 orthotopic heart transplantation (OHT) patients across 135 centers and 12 300 orthotopic lung transplantation (OLT) patients across 67 centers were included in the study. An algorithm was constructed that "closed" the lowest volume center in a region and referred its patients to the highest volume center. In the unadjusted analysis, referred patients were assigned the highest volume center's 1-year mortality rate, and the difference in deaths per region before and after closure was computed. An adjusted analysis was performed using multivariable logistic regression using recipient and donor variables. The primary outcome was the potential number of lives saved at 1 year after transplant. In adjusted OHT analysis, 10 lives were saved (95% confidence interval [CI] 9-11) after one center closure and 240 lives were saved (95% CI 209-272) after up to five center closures per region, with the latter resulting in 1624 total patient referrals (13.2% of OHT patients). For OLT, lives saved ranged from 29 (95% CI 26-32) after one center closure per region to 240 (95% CI 224-256) after up to five regional closures, but the latter resulted in 2999 referrals (24.4% of OLT patients). Increased referral distances would severely limit access to care for rural and resource-limited populations.

Generation-6 hydroxyl PAMAM dendrimers improve CNS penetration from intravenous administration in a large animal brain injury model

Hypothermic circulatory arrest (HCA) provides neuroprotection during cardiac surgery but entails an ischemic period that can lead to excitotoxicity, neuroinflammation, and subsequent neurologic injury. Hydroxyl polyamidoamine (PAMAM) dendrimers target activated microglia and damaged neurons in the injured brain, and deliver therapeutics in small and large animal models. We investigated the effect of dendrimer size on brain uptake and explored the pharmacokinetics in a clinically-relevant canine model of HCA-induced brain injury. Generation 6 (G6, ~6.7nm) dendrimers showed extended blood circulation times and increased accumulation in the injured brain compared to generation 4 dendrimers (G4, ~4.3nm), which were undetectable in the brain by 48h after final administration. High levels of G6 dendrimers were found in cerebrospinal fluid (CSF) of injured animals with a CSF/serum ratio of ~20% at peak, a ratio higher than that of many neurologic pharmacotherapies already in clinical use. Brain penetration (measured by drug CSF/serum level) of G6 dendrimers correlated with the severity of neuroinflammation observed. G6 dendrimers also showed decreased renal clearance rate, slightly increased liver and spleen uptake compared to G4 dendrimers. These results, in a large animal model, may offer insights into the potential clinical translation of dendrimers.

Risk Factors for De Novo Malignancy Following Lung Transplantation

Risk factors for non-skin cancer de novo malignancy (DNM) after lung transplantation have yet to be identified. We queried the United Network for Organ Sharing database for all adult lung transplant patients between 1989 and 2012. Standardized incidence ratios (SIRs) were computed by comparing the data to Surveillance, Epidemiology, and End Results Program data after excluding skin squamous/basal cell carcinomas. We identified 18 093 adult lung transplant patients; median follow-up time was 1086 days (interquartile range 436-2070). DNMs occurred in 1306 patients, with incidences of 1.4%, 4.6%, and 7.9% at 1, 3, and 5 years, respectively. The overall cancer incidence was elevated compared with that of the general US population (SIR 3.26, 95% confidence interval [CI]: 2.95-3.60). The most common cancer types were lung cancer (26.2% of all malignancies, SIR 6.49, 95% CI: 5.04-8.45) and lymphoproliferative disease (20.0%, SIR 14.14, 95% CI: 9.45-22.04). Predictors of DNM following lung transplantation were age (hazard ratio [HR] 1.03, 95% CI: 1.02-1.05, p < 0.001), male gender (HR 1.20, 95% CI: 1.02-1.42, p = 0.03), disease etiology (not cystic fibrosis, idiopathic pulmonary fibrosis or interstitial lung disease, HR 0.59, 95% CI 0.37-0.97, p = 0.04) and single-lung transplantation (HR 1.64, 95% CI: 1.34-2.01, p < 0.001). Significant interactions between donor or recipient smoking and single-lung transplantation were noted. On multivariable survival analysis, DNMs were associated with an increased risk of mortality (HR 1.44, 95% CI: 1.10-1.88, p = 0.009).

Accumulation and cellular localization of nanoparticles in an ex vivo model of acute lung injury

BACKGROUND

The benefit of nanomedicine in mitigating acute lung injury (ALI) is currently unknown. Therefore, we introduced the generation IV polyamidoamine dendrimers with neutral surface property (dendrimer) into our established ex vivo animal model and sought to determine their biodistribution to define their cellular uptake profile and to evaluate their potential as a drug delivery candidate for the treatment of ischemia-reperfusion-induced ALI.

METHODS

Eight rabbit heart-lung blocks were harvested and exposed to 18 h of cold ischemia. The heart-lung blocks were then reperfused with rabbit donor blood. Dendrimer was conjugated to fluorescein isothiocyanate (D-FITC) for localization and quantification studies. D-FITC (30 mg or 150 mg) was injected into the bypass circuit and baseline, 1- and 2-h tissue samples were obtained to determine percent uptake. Low (10×) and high (40×) magnification images were obtained using confocal microscopy to confirm the accumulation and to determine the cellular targets of the dendrimer.

RESULTS

Four heart-lung blocks were exposed to 30 mg and four to 150 mg of D-FITC. After adjusting for dry weight, the mean uptake in the 30 and 150 mg samples after 2 h of reperfusion were 0.79 ± 0.16% and 0.39 ± 0.22% of perfused doses, respectively. Confocal imaging demonstrated dendrimer uptake in epithelial cells and macrophages.

CONCLUSIONS

Fluorescently tagged dendrimers demonstrated injury-dependent tissue accumulation in a variety of different cell types. This unique approach will allow conjugation to and delivery of multiple agents with the potential of mitigating ALI injury while avoiding systemic toxicity.

Planned Versus Unplanned Reexplorations for Bleeding: A Comparison of Morbidity and Mortality

BACKGROUND

Mediastinal reexplorations for bleeding are associated with significant morbidity and mortality. This study hypothesized that bleeding patients who undergo delayed chest closure after an initial operation experience similar outcomes in comparison with patients who have initial chest closure and later require an unplanned reexploration.

METHODS

This study included all patients in the Johns Hopkins University School of Medicine (Baltimore, MD) institutional Society of Thoracic Surgeons (STS) database who underwent cardiac surgical procedures or thoracic transplantation from 2011 to June 2014, had an intraoperative red blood cell transfusion requirement of 2 units or more, and required mediastinal reexploration for bleeding. Reexplorations were classified as planned (temporary chest closure for a planned "second look") or unplanned (initial sternal closure and subsequent reexploration). The two groups were then propensity matched. The primary outcome was 30-day mortality. Secondary outcomes were major complication rates, hospital length of stay, duration of mechanical ventilation, and incidence of postoperative pneumonia and cardiac arrest.

RESULTS

Among 3,293 patients, 110 (3.3%) met inclusion criteria and required mediastinal reexploration for bleeding. This group included 62 planned (56%) and 48 unplanned (44%) reexplorations. After propensity matching 30 pairs of patients across 16 variables, operative mortality rates were comparable (37% vs 37%; p = 1.00) between unplanned and planned reexploration cohorts. There were no differences in rates of deep sternal wound infection, renal failure, postoperative hospital length of stay, pneumonia, or cardiac arrest, with the exception of a higher rate of prolonged intubation (93% vs 53%; p < 0.01) in the planned reexploration group.

CONCLUSIONS

Delayed sternal closure is a safe alternative to initial definitive chest closure when concern exists for postoperative bleeding.

Incidence of late atrial fibrillation in bilateral lung versus heart transplants

BACKGROUND

We compared the incidence of late-onset atrial fibrillation in orthotopic heart transplant recipients and bilateral orthotopic lung transplant recipients.

METHODS

We reviewed the records of all heart and lung transplant operations carried out in our institution between 1995 and 2015. We performed 1:1 propensity-matching based on patient age, sex, body mass index, and hypertension. Our primary outcome, late-onset atrial fibrillation, was defined as atrial fibrillation occurring after discharge following hospitalization for transplantation.

RESULTS

Over the study period, 397 orthotopic heart transplants and 240 bilateral orthotopic lung transplants were performed. Propensity matching resulted in 173 pairs who were matched with respect to age, sex, body mass index, and preoperative hypertension. The median follow-up was 5.3 years for heart transplant patients and 3.1 years for lung transplant patients. Late-onset atrial fibrillation occurred in 11 heart transplant patients (5 of whom had biopsy-proven evidence of rejection) and 19 lung transplant patients (2 of whom had biopsy-proven evidence of rejection). On Kaplan-Meier analysis, the probability of late-onset atrial fibrillation at 5 years was 4.3% for heart transplant patients vs. 13.9% for lung transplant patients (log-rank p = 0.01).

CONCLUSIONS

We documented an increased probability of late-onset atrial fibrillation among bilateral orthotopic lung transplant patients compared to orthotopic heart transplant patients. This was a hypothesis-generating study that suggests a potential role for cardiac autonomic innervation in the genesis of atrial fibrillation.