Publications by authors named "Alan S Chou"

8 Publications

  • Page 1 of 1

Heart-Kidney and Heart-Liver Transplantation Provide Immunoprotection to the Cardiac Allograft.

Ann Thorac Surg 2019 08 15;108(2):458-466. Epub 2019 Mar 15.

Division of Cardiovascular Surgery, Hospital of the University of Pennsylvania, Philadelphia. Electronic address:

Background: Prior single-center studies suggest that kidney and liver allografts are immunoprotective toward transplanted hearts. The broader effects of the simultaneous transplantation of kidney or liver on protection from rejection are unclear.

Methods: The United Network for Organ Sharing database for heart transplantation was queried from 1987 to 2015 and stratified into patients undergoing heart-liver transplantation (HLT) (n = 192), heart-kidney transplantation (HKT) (n = 1,174), and heart-only transplantation (HT) (n = 61,471). Perioperative and follow-up data were compared between HT versus HLT and HT versus HKT groups using analysis of variance (continuous), chi-square test (categorical), and Kaplan-Meier curves (survival).

Results: HKT patients were older (51.2 ± 13.4 years of age) compared with HT patients (45.6 ± 19.2 years of age; p < 0.0001), with higher rate of diabetes (33.8% versus 14.8%; p < 0.0001) and dialysis (49.7% versus 2.1%; p < 0.0001). HKT (46.2%) and HLT (49.5%) patients had more urgent need for transplantation (status 1A) compared with HT patients (32%; p < 0.0001). Acute rejection episodes before discharge were lower in the HLT group (7.1% versus 3.1%; p = 0.03). Ten-year patient survivals were similar for HT (53.6%) versus HKT (56.7%) (p = 0.13) versus HLT (60.4%) (p = 0.09). Treatment for rejection during the first posttransplant year was lower in HLT (2.1%) and HKT (8.4%) compared with HT (17.4%) (p < 0.0001 for both). Cox multivariate analysis showed that cardiac allograft survival was improved in HKT (odds ratio, 0.58; 95% confidence interval [CI], 0.49 to 0.70; p < 0.0001). Additionally, HKT (hazard ratio, 0.52; 95% CI, 0.45 to 0.60; p < 0.0001) and HLT (hazard ratio, 0.24; 95% CI, 0.15 to 0.39; p < 0.0001) were associated with improved freedom from rejection.

Conclusions: Nationally, HKT and HLT have equivalent postoperative outcomes as HT. Simultaneous kidney or liver transplantation confers an improved clinical and immunologic outcome.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.athoracsur.2019.02.012DOI Listing
August 2019

Positive family history of aortic dissection dramatically increases dissection risk in family members.

Int J Cardiol 2017 Aug 25;240:132-137. Epub 2017 Apr 25.

Aortic Institute at Yale-New Haven Hospital, Yale University School of Medicine, New Haven, CT, United States. Electronic address:

Objectives: Although family members of patients with aortic dissection (AoD) are believed to be at higher risk of AoD, the prognostic value of family history (FH) of aortic dissection (FHAD) in family members of patients with AoD has not been studied rigorously. We seek examine how much a positive FHAD increases the risk of developing new aortic dissection (AoD) among first-degree relatives.

Methods: Patients with AoD at our institution were analyzed for information of FHAD. Positive FHAD referred to that AoD occurred in index patient and one or more first-degree relatives. Negative FHAD was defined as the condition in which only one case of AoD (the index patient) occurred in the family. The age at AoD, exposure years in adulthood before AoD, and annual probability of AoD among first-degree relatives were compared between patients with negative and positive FHADs.

Results: FHAD was positive in 32 and negative in 68 among the 100 AoD patients with detailed family history information. Mean age at dissection was 59.9±14.7years. Compared to negative FHAD, patients with positive FHAD dissected at significantly younger age (54.7±16.8 vs 62.4±13.0years, p=0.013), had more AoD events in first-degree relatives (2.3±0.6 vs 1.0±0.0, p<0.001), and shorter exposure years per AoD event (18.3±6.7 vs 43.1±8.5, p<0.001). Annual probability of AoD per first-degree relative was 2.77 times higher in patients with positive than negative FHADs (0.0100±0.0057 vs 0.0036±0.0014, p<0.001).

Conclusions: A positive FHAD confers a significantly increased risk of developing aortic dissection on family members, with a higher annual probability of aortic dissection, a shorter duration of "exposure time" before dissection occurs and a lower mean age at time of dissection.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ijcard.2017.04.080DOI Listing
August 2017

Twenty-five year outcomes following composite graft aortic root replacement.

J Card Surg 2017 Feb 14;32(2):99-109. Epub 2016 Dec 14.

Aortic Institute at Yale-New Haven Hospital, Yale University School of Medicine, New Haven, Connecticut.

Background: Operative choices for aortic root disease include traditional root replacement with a composite valved graft as well as various valve-sparing and root repair procedures.

Objectives: To report our experience with traditional composite graft aortic root replacement by a single surgeon over a 25-year period in 449 patients, focusing on long-term survival and freedom from late reoperation and adverse events.

Methods: The coronary button technique was used in all patients. Mean age was 56.1 ± 14.0 years (range 14-87) with 83% males (373/449). Valve prosthesis was mechanical in 343 (76%) and bioprosthetic in 106 (24%). A modified Cabrol procedure (Dacron coronary graft) was employed in 10% (45/449) and concomitant coronary artery bypass graft in 10.9% (49/449). There were 15.8% (71/449) urgent/emergent and 8.2% (37/449) redo procedures. Survival follow-up was 100%. Mean follow-up was 7.0 ± 5.1 years (range 0.1-24.8).

Results: Operative mortality occurred in 14 patients (3.1%) and was 2.2% (9/418) in non-dissection and 1.9% (7/361) in elective first-time operations. Stroke and re-exploration for bleeding occurred in nine (2.0%) and 20 (4.5%) patients, respectively. Major late events included bleeding in 2.5% (11/435) and thromboembolism in 1.1% (5/435). At 5, 10, and 20 years, freedom from major events and reoperations on the root were 97.8, 95.4, and 94.39%, and 99.0, 99.0, and 97.9%, respectively. Survival in patients aged <60 years was 92.0, 90.1, and 79.8% at five, 10, and 20 years versus 88.4, 67.9, and 42.6% in patients aged ≥60 years (p = 0.001). Compared with age- and gender-matched controls, survival was not significantly different (p = 0.20).

Conclusions: Composite graft aortic root replacement is associated with low operative risk, excellent long-term survival, and low incidence of reoperation and late events.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/jocs.12875DOI Listing
February 2017

Computed Tomography Imaging Artifact Simulating Type A Aortic Dissection.

Aorta (Stamford) 2016 Apr 1;4(2):72-73. Epub 2016 Apr 1.

Aortic Institute at Yale-New Haven Hospital, Yale University School of Medicine, New Haven, Connecticut, USA.

Contrast-enhanced computed tomography (CT) is an effective tool for assessment of thoracic aortic disease in the modern era. Here, we describe a case of Type A aortic dissection incidentally detected by CT in a 63-year old man. Upon more precise imaging with electrocardiography (ECG)-gated CT, the dissection vanished, revealing it to be an aortic motion artifact. This report highlights the importance of motion artifacts mimicking a dissection flap. CT imaging gated with ECG can distinguish a dissection flap from an artifact.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.12945/j.aorta.2015.15.021DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5054759PMC
April 2016

Do Familial Aortic Dissections Tend to Occur at the Same Age?

Ann Thorac Surg 2017 Feb 25;103(2):546-550. Epub 2016 Aug 25.

Aortic Institute at Yale-New Haven Hospital, Yale University School of Medicine, New Haven, Connecticut. Electronic address:

Background: Prediction of the age at aortic dissection for family members of aortic dissection patients would enhance early detection and clinical management. We sought to determine whether these dissections tend to cluster by age in family members of the dissection patients.

Methods: Ages at dissection were examined, including 51 sporadic dissectors (one dissection in family) and 39 familial dissectors (two or more dissections in family) from 16 families. Differences between sporadic and familial dissectors and relationships between ages at dissection in family members were analyzed by linear regression and clustering analysis.

Results: Age at dissection was significantly younger in familial versus sporadic dissectors (54.1 ± 15.2 years versus 63.1±12.4 years, p = 0.002). Regression analysis of pairs of family member ages at dissection found a moderately close linear fit (R = 0.35). Cluster analysis indicated that age at onset of family dissectors increases as age of proband dissector increases. More than 50% of familial dissections occurred within 10 years of the median onset age for any given age decade. For familial dissectors with onset age of 30 to 49 years, 71% of other family member dissections also occurred at age 30 to 49 years, and no dissections occurred above the age of 63 years. For familial dissectors with onset age of 60 to 79 years, 80% of other family member dissections occurred beyond the age of 50 years.

Conclusions: Familial dissections occur earlier than sporadic dissections. Dissections cluster by age in families, and age at onset can predict the age of other dissectors. This finding argues for consideration of prophylactic resection of an aneurysm in family members approaching the age at onset of prior thoracic aortic dissection.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.athoracsur.2016.06.007DOI Listing
February 2017

Long-term behavior of aortic intramural hematomas and penetrating ulcers.

J Thorac Cardiovasc Surg 2016 Feb 16;151(2):361-72, 373.e1. Epub 2015 Sep 16.

Aortic Institute at Yale-New Haven Hospital, Yale University School of Medicine, New Haven, Conn. Electronic address:

Objective: For intramural hematoma and penetrating atherosclerotic ulcer, long-term behavior and treatment are controversial. This study evaluates the long-term behavior of intramural hematoma and penetrating atherosclerotic ulcer, including radiologic follow-up and survival analysis.

Methods: Between 1995 and 2014, 108 patients (mean age, 70.8 ± 10 years; 56% female) presented with intramural hematoma or penetrating atherosclerotic ulcer to Yale-New Haven Hospital (New Haven, Conn). We reviewed the medical records, radiology, and online mortality databases.

Results: Ten of 55 patients (18%) with intramural hematoma and 17 of 53 patients (32%) with penetrating atherosclerotic ulcer had rupture state symptoms on admission, both greater than type A (8%) or type B dissection (4%) (P < .001). No branch vascular occlusion occurred. For patients with intramural hematoma with follow-up imaging, 8 of 14 (57%) worsened (mean follow-up, 9.4 months) and 6 (43%) underwent late surgery. For patients with penetrating atherosclerotic ulcer with follow-up imaging, 6 of 20 (30%) worsened and underwent late surgery, and 11 (55%) showed no change (mean follow-up, 34.3 months). Overall survivals were 77%, 70%, 58%, and 33% at 1, 3, 5, and 10 years, respectively. No operative deaths occurred for patients with nonrupture state. Patients with penetrating atherosclerotic ulcer with initial surgical treatment had better long-term survival than patients treated medically (P = .037). In the intramural hematoma group, no such difference was observed (P = .10).

Conclusions: At presentation, the incidence of early rupture of intramural hematoma and penetrating atherosclerotic ulcer was higher than for typical dissection. For branch vessels, intramural hematoma never occludes branch arteries. On imaging follow-up, patients with intramural hematoma and penetrating atherosclerotic ulcer rarely improved, with late surgery commonly needed. Better survival was observed for the initial surgical management of patients with penetrating atherosclerotic ulcer compared with initial medical management.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jtcvs.2015.09.012DOI Listing
February 2016

Atypical aortic arch branching variants: A novel marker for thoracic aortic disease.

J Thorac Cardiovasc Surg 2015 Jun 14;149(6):1586-92. Epub 2015 Feb 14.

Aortic Institute at Yale-New Haven Hospital, Yale University School of Medicine, New Haven, Conn. Electronic address:

Objective: To examine the potential of aortic arch variants, specifically bovine aortic arch, isolated left vertebral artery, and aberrant right subclavian artery, as markers for thoracic aortic disease (TAD).

Methods: We screened imaging data of 556 patients undergoing surgery due to TAD for presence of aortic arch variations. Demographic data were collected during chart review and compared with a historical control group of 4617 patients.

Results: Out of 556 patients with TAD, 33.5% (186 patients) demonstrated anomalies of the aortic arch, compared with 18.2% in the control group (P < .001). Three hundred seventy (66.5%) had no anomaly of the aortic arch. Bovine aortic arch emerged as the most common anomalous branch pattern with a prevalence of 24.6% (n = 137). Thirty-five patients (6.3%) had an isolated left vertebral artery, and 10 patients (1.8%) had an aberrant right subclavian artery. When compared with the control group, all 3 arch variations showed significant higher prevalence in patients with TAD (P < .001). Patients with aortic aneurysms and anomalous branch patterns had hypertension less frequently (73.5% vs 81.8%; P = .048), but had a higher rate of bicuspid aortic valve (40.8% vs 30.6%; P = .042) when compared with patients with aneurysms but normal aortic arch anatomy. Patients with aortic branch variations were significantly younger (58.6 ± 13.7 years vs 62.4 ± 12.9 years; P = .002) and needed intervention for the aortic arch more frequently than patients with normal arch anatomy (46% vs 34.6%; P = .023).

Conclusions: Aortic arch variations are significantly more common in patients with TAD than in the general population. Atypical branching variants may warrant consideration as potential anatomic markers for future development of TAD.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jtcvs.2015.02.019DOI Listing
June 2015

Critical-point universality in adsorption: the effect of charcoal on a mixture of isobutyric acid and water near the consolute point.

Phys Rev E Stat Nonlin Soft Matter Phys 2011 Jun 16;83(6 Pt 1):061201. Epub 2011 Jun 16.

Department of Chemical Engineering, University of Alabama in Huntsville, Huntsville, Alabama 35899, USA.

The mixture of isobutyric acid and water has a consolute point at a temperature of 25.75 °C and mole fraction 0.1148 isobutyric acid. When charcoal is added to this mixture, the concentration of isobutyric acid is reduced by adsorption. We have measured the action of charcoal on solutions of isobutyric acid and water as a function of isobutyric acid mole fraction at temperatures of 25.85 and 32.50 °C. At the higher temperature, the specific adsorption density (y(2)(α)/m) satisfies the Freundlich equation (y(2)(α)/m)=KX(2)(1/n), where y(2)(α) is the mass of isobutyric acid adsorbed, m is the mass of charcoal, X(2) is the equilibrium mole fraction of isobutyric acid, n is the Freundlich index, and K=K(T) is an amplitude that depends upon the temperature T. At 25.85 °C, a critical endpoint is located at an isobutyric acid mole fraction X(2)(ce)=0.09. When compared with the Freundlich equation at this temperature, a plot of the specific adsorption density as a function of X(2) in the vicinity of the critical-endpoint composition assumes a shape which is reminiscent of the derivative of a Dirac delta function. Using critical-point scaling theory, we show that this divergent pattern is consistent with the principle of critical point universality.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1103/PhysRevE.83.061201DOI Listing
June 2011
-->