Michael Singh

Mutations in Smooth Muscle Alpha-Actin (ACTA2) Cause Coronary Artery Disease, Stroke, and Moyamoya Disease, Along with Thoracic Aortic Disease

The vascular smooth muscle cell (SMC)-specific isoform of alpha-actin (ACTA2) is a major component of the contractile apparatus in SMCs located throughout the arterial system. Heterozygous ACTA2 mutations cause familial thoracic aortic aneurysms and dissections (TAAD), but only half of mutation carriers have aortic disease. Linkage analysis and association studies of individuals in 20 families with ACTA2 mutations indicate that mutation carriers can have a diversity of vascular diseases, including premature onset of coronary artery disease (CAD) and premature ischemic strokes (including Moyamoya disease [MMD]), as well as previously defined TAAD. Sequencing of DNA from patients with nonfamilial TAAD and from premature-onset CAD patients independently identified ACTA2 mutations in these patients and premature onset strokes in family members with ACTA2 mutations. Vascular pathology and analysis of explanted SMCs and myofibroblasts from patients harboring ACTA2 suggested that increased proliferation of SMCs contributed to occlusive diseases. These results indicate that heterozygous ACTA2 mutations predispose patients to a variety of diffuse and diverse vascular diseases, including TAAD, premature CAD, ischemic strokes, and MMD. These data demonstrate that diffuse vascular diseases resulting from either occluded or enlarged arteries can be caused by mutations in a single gene and have direct implications for clinical management and research on familial vascular diseases.

MELD-XI score and cardiac mortality or transplantation in patients after Fontan surgery

Objective The Fontan operation is a staged palliation for complex congenital heart disease and single ventricle physiology. Perioperative survivors of the Fontan operation experience long-term cardiac complications, including death. Liver and renal dysfunction are reported in these patients and have a direct effect on morbidity and mortality. This study aims to investigate whether the Model for End-stage Liver Disease eXcluding INR score (function of creatinine and total bilirubin, MELD-XI) predicts risk for cardiac mortality or transplantation in patients with Fontan circulation. Design and setting Retrospective, single-centre study. Time of first evaluation was the time of the earliest available MELD-XI score measurement, and follow-up was terminated by a cardiac event or by the last clinical evaluation. Patients Patients surviving after Fontan surgery and evaluated at Boston Childrens Hospital between 1993 and 2008. Main outcome measure Composite endpoint of sudden death, death from congestive heart failure or cardiac transplantation. Results The MELD-XI score was calculated as MELD-XI=11.76(loge creatinine)+5.112(loge total bilirubin)+9.44. Ninety-six patients were included (52 male, median age 26 years). After a mean follow-up period of 5.7 years, 18 patients (19%) experienced the composite end point. Baseline MELD-XI score was independently and directly related to the incidence of the composite endpoint (HR for high MELD-XI score group of 7.76, 95% CI 2.05 to 29.33, p=0.008). Conclusions Fontan patients with a higher MELD-XI score have shorter freedom from sudden cardiac death, death from congestive heart failure and cardiac transplantation.

Transient Elastography May Identify Fontan Patients with Unfavorable Hemodynamics and Advanced Hepatic Fibrosis

BACKGROUND Transient elastography (TE) offers a noninvasive correlate with the degree of hepatic fibrosis. However, factors other than fibrosis affect liver stiffness. We sought to determine whether hepatic congestion related to hemodynamics in Fontan circulation influences liver stiffness measurement (LSM) assessed by TE. METHODS We studied 45 subjects with Fontan circulation undergoing cardiac catheterization with or without simultaneous liver biopsy. Subjects underwent TE within 5 days before catheterization. Clinical history, hemodynamic and biopsy data, and hepatic biomarkers were collected. Five subjects who had previously undergone liver biopsy and TE were also included. RESULTS Median age was 13.1 years (range 2.4-57.8); median time since Fontan was 9.9 years (range 0.1-32.5). No subject had known hepatitis C. Mean LSM for the entire cohort was 21.4 ± 10.8 kPa. Univariate regression analysis using LSM as a continuous outcome variable shows significant correlations with age (R = 0.35, P = .01), time since Fontan (R = 0.41, P = .003), Fontan pressure (R = 0.31, P = .04), cardiac index (R = 0.33, P = .03), pulmonary vascular resistance (R = 0.34, P = .03), systemic arterial oxygen saturation (R = 0.31, P = .04), and platelet count (R = 0.29, P = .05). On multiple regression analysis, Fontan pressure (β = 0.901, P = .03) and cardiac index (β = 2.703, P = .02) were significant predictors of LSM with overall model R(2) = 0.206. Univariate analysis shows LSM to be associated with more severe centrilobular fibrosis (P = .05). CONCLUSIONS Higher LSM is associated with unfavorable Fontan hemodynamics and advanced centrilobular hepatic fibrosis. TE may be a useful tool for identifying Fontan patients who warrant invasive testing.

Portal and centrilobular hepatic fibrosis in Fontan circulation and clinical outcomes

BACKGROUND The Fontan operation redirects venous blood flow directly to the pulmonary circulation in subjects with single ventricle anatomy. Congestive hepatopathy and cirrhosis have been described in subjects with Fontan circulation, but the prevalence of and predictors for liver disease remain unknown. METHODS We performed a retrospective study of liver histopathology in Fontan subjects who had liver biopsy or autopsy. All specimens were graded using a pre-determined protocol. Additional data were collected through chart review. Among 68 subjects, specimens were obtained at a median age of 23.2 years (range 5.0 to 52.7 years). Median time since Fontan was 18.1 years (range 1.2 to 32.7 years). RESULTS Centrilobular fibrosis was seen in every specimen, with 41.2% showing Grade 4 centrilobular fibrosis. Portal fibrosis was seen in 82.3% of specimens, with 14.7% showing cirrhosis. Megamitochondria were seen in 58.8% of specimens. Centrilobular fibrosis grade was greater in those with a dominant left or right ventricle than in those with a combined right and left systemic ventricle (p = 0.008). Portal fibrosis grade correlated with alkaline phosphatase (p = 0.04) and mode of biopsy (p = 0.02). Neither centrilobular fibrosis nor portal fibrosis grade was predictive of transplant-free survival or overall survival. CONCLUSIONS Individuals with Fontan physiology have a high prevalence of hepatic fibrosis. Signs and symptoms of liver disease did not predict histopathologic findings. Few risk factors for advanced disease were identified. Histopathology findings did not predict transplant-free survival. The role of liver biopsy in this population remains uncertain.

Pheochromocytoma and Paraganglioma in Cyanotic Congenital Heart Disease

CONTEXT Aberrant cellular oxygen sensing is a leading theory for development of pheochromocytoma (PHEO) and paraganglioma (PGL). OBJECTIVE The objective of the study was to test the hypothesis that chronic hypoxia in patients with cyanotic congenital heart disease (CCHD) increases the risk for PHEO-PGL. DESIGN/SETTING/PARTICIPANTS We investigated the association between CCHD and PHEO-PGL with two complementary studies: study 1) an international consortium was established to identify congenital heart disease (CHD) patients with a PHEO-PGL diagnosis confirmed by pathology or biochemistry and imaging; study 2) the 2000-2009 Nationwide Inpatient Survey, a nationally representative discharge database, was used to determine population-based cross-sectional PHEO-PGL frequency in hospitalized CCHD patients compared with noncyanotic CHD and those without CHD using multivariable logistic regression adjusted for age, sex, and genetic PHEO-PGL syndromes. RESULTS In study 1, we identified 20 PHEO-PGL cases, of which 18 had CCHD. Most presented with cardiovascular or psychiatric symptoms. Median cyanosis duration for the CCHD PHEO-PGL cases was 20 years (range 1-57 y). Cases were young at diagnosis (median 31.5 y, range 15-57 y) and 7 of 18 had multiple tumors (two bilateral PHEO; six multifocal or recurrent PGL), whereas 11 had single tumors (seven PHEO; four PGL). PGLs were abdominal (13 of 17) or head/neck (4 of 17). Cases displayed a noradrenergic biochemical phenotype similar to reported hypoxia-related PHEO-PGL genetic syndromes but without clinical signs of such syndromes. In study 2, hospitalized CCHD patients had an increased likelihood of PHEO-PGL (adjusted odds ratio 6.0, 95% confidence interval 2.6-13.7, P < .0001) compared with those without CHD; patients with noncyanotic CHD had no increased risk (odds ratio 0.9, P = .48). CONCLUSIONS There is a strong link between CCHD and PHEO-PGL. Whether these rare diseases coassociate due to hypoxic stress, common genetic or developmental factors, or some combination requires further investigation.

A shifting approach to management of the thoracic aorta in bicuspid aortic valve.

OBJECTIVES The scientific understanding of aortic dilation associated with bicuspid aortic valve (BAV) has evolved during the past 2 decades, along with improvements in diagnostic technology and surgical management. We aimed to evaluate secular trends and predictors of thoracic aortic surgery among patients with BAV in the United States. METHODS We used the 1998-2009 Nationwide Inpatient Sample, an administrative dataset representative of US hospital admissions, to identify hospitalizations for adults aged 18 years or more with BAV and aortic valve or thoracic aortic surgery. Covariates included age, gender, year, aortic dissection, endocarditis, thoracic aortic aneurysm, number of comorbidities, hospital teaching status and region, primary insurance, and concomitant coronary artery bypass surgery. RESULTS Between 1998 and 2009, 48,736 ± 3555 patients with BAV underwent aortic valve repair or replacement and 1679 ± 120 patients with BAV underwent isolated thoracic aortic surgery. The overall number of surgeries increased more than 3-fold, from 4556 ± 571 in 1998/1999 to 14,960 ± 2107 in 2008/2009 (P < .0001). The proportion of aortic valve repair or replacement including concomitant thoracic aortic surgery increased from 12.8% ± 1.4% in 1998/1999 to 28.5% ± 1.6% in 2008/2009, which mirrored an increasing proportion of patients with a diagnosis of thoracic aortic aneurysm. Mortality was equivalent for patients undergoing aortic valve repair or replacement with thoracic aortic surgery and those undergoing isolated aortic valve repair or replacement (1.8% ± 0.3% vs 1.5% ± 0.2%; multivariable odds ratio, 1.02; 95% confidence interval, 0.67-1.57), with decreasing mortality over the study period (from 2.5% ± 0.6% in 1998/1999 to 1.5% ± 0.2% in 2008/2009; multivariable odds ratio per 2-year increment, 0.89; 95% confidence interval, 0.81-0.99; P = .03). Total charges for BAV surgical hospitalizations increased more than 7.5-fold from approximately

Galectin‐3 Is Elevated and Associated With Adverse Outcomes in Patients With Single‐Ventricle Fontan Circulation

156 million in 1998 to

Distinct effects of losartan and atenolol on vascular stiffness in Marfan syndrome.

1.2 billion in 2009 (inflation-adjusted 2009 dollars). CONCLUSIONS There was a marked increase in the use of thoracic aortic surgery among patients with BAV.

Predictive value of biomarkers of hepatic fibrosis in adult Fontan patients

Background Galectin‐3 may play a role in cardiac and noncardiac fibrosis, and elevated circulating levels of this protein predict adverse outcomes in patients with heart failure who do not have congenital heart disease. We investigated galectin‐3 in adults with single‐ventricle Fontan circulation, patients who are prone to premature clinical deterioration in the context of extensive multiorgan fibrosis. Methods and Results We measured plasma galectin‐3 concentrations in 70 ambulatory adult Fontan patients and 21 age‐ and sex‐matched control participants. Galectin‐3 level was significantly higher in the Fontan group (11.85 ng/mL, interquartile range 9.9 to 15.0 ng/mL) versus the control group (9.4 ng/mL, interquartile range 8.2 to 10.8 ng/mL; P<0.001). Among Fontan patients, galectin‐3 was positively correlated with age, uric acid, and high‐sensitivity C‐reactive protein and negatively correlated with estimated glomerular filtration rate. There was no significant relationship between galectin‐3 and oxygen saturation, Fontan type, or ventricular morphology. Over a median follow‐up of 461 days, 15 events occurred among the Fontan patients: 12 nonelective hospitalizations (with 2 subsequent deaths) and 3 deaths without prior hospitalization. Patients with elevated galectin‐3 (n=19, defined as >2 SD above the control group mean value) had a higher risk of nonelective hospitalization or death (hazard ratio 6.0, 95% CI 2.1 to 16.8, P<0.001). This relationship persisted after individual adjustment for covariates including age, New York Heart Association functional class, C‐reactive protein, and estimated glomerular filtration rate and after multivariable adjustment for independently predictive covariates (hazard ratio 9.2, 95% CI 2.4 to 35.2, P=0.001). Conclusions Galectin‐3 concentrations are elevated among adults with a Fontan circulation, and elevated galectin‐3 is associated with an increased risk of nonelective cardiovascular hospitalization or death.

Surgical management of bronchopleural fistula in pediatric empyema and necrotizing pneumonia: efficacy of the serratus anterior muscle digitation flap

We conducted a randomized, double-blind trial of losartan (100 mg QD) versus atenolol (50 mg QD) for 6 months in adults with Marfan syndrome. Carotid-femoral pulse wave velocity (PWV), central augmentation index (AIx), aortic diameter and left ventricular (LV) function were assessed with arterial tonometry and echocardiography. Thirty-four subjects (18 female; median age 35 years, IQR 27, 45) were randomized. Central systolic and diastolic blood pressure decreased comparably with atenolol and losartan (p = 0.64 and 0.31, respectively); heart rate decreased with atenolol (p = 0.02), but not with losartan. PWV decreased in patients treated with atenolol (–1.15 ± 1.68 m/s; p = 0.01), but not in those treated with losartan (–0.22 ± 0.59 m/s; p = 0.15; between-group difference p = 0.04). In contrast, AIx decreased in the losartan group (–9.6 ± 8.6%; p < 0.001) but not in the atenolol group (0.9 ± 6.2%, p = 0.57; between-group difference p < 0.001). There was no significant change in aortic diameters or LV ejection fraction in either treatment group. In adults with Marfan syndrome, 6 months of treatment with atenolol improves PWV, whereas losartan reduces the AIx. By improving vascular stiffness via distinct mechanisms of action, there is physiologic value to considering the use of both medications in individuals with Marfan syndrome.