Adherence to clinical practice guidelines for pulmonary valve intervention after tetralogy of Fallot repair: A nationwide cohort study

Objectives

To determine guideline adherence pertaining to pulmonary valve replacement (PVR) referral after tetralogy of Fallot (TOF) repair.

Methods

Children and adults with cardiovascular magnetic resonance imaging scans and at least moderate pulmonary regurgitation were prospectively enrolled in the Comprehensive Outcomes Registry Late After TOF Repair (CORRELATE). Individuals with previous PVR were excluded. Patients were classified according to presence (+) versus absence (-) of PVR and presence (+) versus absence (-) of contemporaneous guideline satisfaction. A validated score (specific activity scale [SAS]) classified adult symptom status.

Results

In total, 498 participants (57% male, mean age 32 ± 14 years) were enrolled from 14 Canadian centers (2013-2020). Mean follow-up was 3.8 ± 1.8 years. Guideline criteria for PVR were satisfied for the majority (n = 422/498, 85%), although referral for PVR occurred only in a minority (n = 167/498, 34%). At PVR referral, most were asymptomatic (75% in SAS class 1). One participant (0.6%) received PVR without meeting criteria (PVR+/indication-). The remainder (n = 75/498, 15%) did not meet criteria for and did not receive PVR (PVR-/indication-). Abnormal cardiovascular imaging was the most commonly cited indication for PVR (n = 61/123, 50%). The SAS class and ratio of right to left end-diastolic volumes were independent predictors of PVR in a multivariable analysis (hazard ratio, 3.33; 95% confidence interval, 1.92-5.8, P < .0001; hazard ratio, 2.78; 95% confidence interval, 2.18-3.55, P < .0001).

Conclusions

Although a majority of patients met guideline criteria for PVR, only a minority were referred for intervention. Abnormal cardiovascular imaging was the most common indication for referral. Further research will be necessary to establish the longer-term clinical impact of varying PVR referral strategies.

Adult Congenital Heart Disease Care in Canada: Has Quality of Care Improved in the Last Decade?

BACKGROUND

Patients with adult congenital heart disease (ACHD) are at increased risk of comorbidity and death compared with the age-matched population. Specialized care is shown to improve survival. The purpose of this study was to analyze current measures of quality of care in Canada compared with those published by our group in 2012.

METHODS

A survey focusing on structure and process measures of care quality in 2020 was sent to 15 ACHD centres registered with the Canadian Adult Congenital Heart Network. For each domain of quality, comparisons were made with those published in 2012.

RESULTS

In Canada, 36,708 patients with ACHD received specialized care between 2019 and 2020. Ninety-five cardiologists were affiliated with ACHD centres. The median number of patients per ACHD clinic was 2000 (interquartile range [IQR]: 1050, 2875). Compared with the 2012 results, this represents a 68% increase in patients with ACHD but only a 19% increase in ACHD cardiologists. Compared with 2012, all procedural volumes increased with cardiac surgeries, increasing by 12% and percutaneous intervention by 22%. Wait time for nonurgent consults and interventions all exceeded national recommendations by an average of 7 months and had increased compared with 2012 by an additional 2 months. Variability in resources were noted across provincial regions.

CONCLUSIONS

Over the past 10 years, ACHD care gaps have persisted, and personnel and infrastructure have not kept pace with estimates of ACHD population growth. Strategies are needed to improve and reduce disparity in ACHD care relative to training, staffing, and access to improved care for Canadians with ACHD.

Tetralogy of Fallot Across the Lifespan: A Focus on the Right Ventricle

Tetralogy of Fallot is a cyanotic congenital heart disease, for which various surgical techniques allow patients to survive to adulthood. Currently, the natural history of corrected tetralogy of Fallot is underlined by progressive right ventricular (RV) failure due to pulmonic regurgitation and other residual lesions. The underlying cellular mechanisms that lead to RV failure from chronic volume overload are characterized by microvascular and mitochondrial dysfunction through various regulatory molecules. On a clinical level, these cardiac alterations are commonly manifested as exercise intolerance. The degree of exercise intolerance can be objectified and aid in prognostication through cardiopulmonary exercise testing. The timing for reintervention on residual lesions contributing to RV volume overload remains controversial; however, interval assessment of cardiac function and volumes by echocardiography and magnetic resonance imaging may be helpful. In patients who develop clinically important RV failure, clinicians should aim to maintain a euvolemic state through the use of diuretics while paying particular attention to preload and kidney function. In patients who develop signs of cardiogenic shock from right heart failure, stabilization through the use of inotropes and pressor is indicated. In special circumstances, the use of mechanical support may be appropriate. However, cardiologists should pay particular attention to residual lesions that may impact the efficacy of the selected device.

Severe Fontan-Associated Liver Disease and Its Association With Mortality

Background Data are rare about the incidence of severe Fontan-associated liver disease (FALD) and its association with mortality. We sought to: (1) estimate the probability of developing severe FALD in patients who undergo the Fontan procedure (Fontan patients), compared with severe liver complications in patients with a ventricular septal defect; (2) assess the severe FALD-mortality association; and (3) identify risk factors for developing severe FALD. Methods and Results Using the Quebec Congenital Heart Disease database, a total of 512 Fontan patients and 10 232 patients with a ventricular septal defect were identified. Kaplan-Meier curves demonstrated significantly higher cumulative risk of severe FALD in Fontan patients (11.95% and 52.24% at 10 and 35 years, respectively), than the risk of severe liver complications in patients with a ventricular septal defect (0.50% and 2.75%, respectively). At 5 years, the cumulative risk of death was 12.60% in patients with severe FALD versus 3.70% in Fontan patients without FALD (log-rank P=0.0171). Cox proportional hazard models identified significant associations between the development of severe FALD and congestive heart failure and supraventricular tachycardia, with hazard ratios (HRs) of 2.36 (95% CI, 1.38-4.02) and 2.45 (95% CI, 1.37-4.39), respectively. More recent Fontan completion was related to reduced risks of severe FALD, with an HR of 0.95 (95% CI, 0.93-0.97) for each more recent year. Conclusions This large-scale population-based study documents that severe FALD in Fontan patients was associated with a >3-fold increase in mortality. The risk of FALD is time-dependent and can reach >50% by 35 years after the Fontan operation. Conditions promoting poor Fontan hemodynamics were associated with severe FALD development.

The Impact of the COVID-19 Pandemic Restrictions on the Provision of Adult Congenital Heart Disease Care Across Canada: A National Survey

Background

The COVID-19 pandemic significantly impacted health care access across Canada with the reduction in in-person evaluations. The aim of the study was to examine the effects of the COVID-19 pandemic on access to health care services among the Canadian population with adult congenital heart disease (ACHD).

Methods

All Canadian adult congenital heart affiliated centres were contacted and asked to collect data on outpatient clinic and procedural volumes for the 2019 and 2020 calendar years. A survey was sent detailing questions on clinic and procedural volumes and wait times before and after pandemic restrictions. Descriptive statistics were used with the Student t-test to compare groups.

Results

In 2019, there were 19,326 ACHD clinic visits across Canada and only 296 (1.5%) virtual clinic visits. However, during the first year of the pandemic, there were 20,532 clinic visits and 11,412 (56%) virtual visits (P < 0.0001). There were no differences in procedural volumes (electrophysiology, cardiac surgery, and percutaneous intervention) between 2019 and 2020. The mean estimated wait times (months) before the pandemic vs the pandemic were as follows: nonurgent consult 5.4 ± 2.6 vs 6.6 ± 4.2 (P = 0.65), ACHD surgery 6.0 ± 3.5 vs 7.0 ± 4.6 (P = 0.47), electrophysiology procedures 6.3 ± 3.3 vs 5.7 ± 3.3 (P = 0.72), and percutaneous intervention 4.6 ± 3.9 vs 4.4 ± 2.3 (P = 0.74).

Conclusions

During the pandemic and restrictions of social distancing, the use of virtual clinic visits helped to maintain continuity in ACHD clinical care, with 56% of ACHD visits being virtual. The procedural volumes and wait times for consultation and percutaneous and surgical interventions were not delayed.

Patient-Reported Outcomes After Tetralogy of Fallot Repair

BACKGROUND

Comprehensive assessment of tetralogy of Fallot (TOF) outcomes extends beyond morbidity and mortality to incorporate patient-reported outcomes (PROs), including quality of life (QOL) and health status (HS).

OBJECTIVES

This study explored PROs in adolescents and adults with TOF and delineated variables associated with PROs.

METHODS

This was a cross-sectional observational study within a larger prospective registry of adolescents and adults with repaired TOF and moderate or greater pulmonary regurgitation from North America, Europe, and Asia. Participants completed PROs, including a QOL linear analogue scale (QOL-LAS) and an HS visual analogue scale (HS-VAS). Scores were classified according to age cohorts: <18, 18 to 25, 26 to 40, and >40 years.

RESULTS

The study included 607 patients (46.3% female; median age 28.5 years). Median QOL-LAS scores (0-100) were similar across age cohorts (85, 80, 80, 80; P = 0.056). Median HS-VAS scores (0-100) were lowest for the oldest cohort (77) compared with the 3 younger cohorts (85, 80, 80) (P = 0.004). With advancing age, there were increased reports of poor mobility (P < 0.001) and pain or discomfort (P = 0.004); problems in these dimensions were reported by 19.1% and 37.2% of patients aged >40 years, respectively. Of factors associated with superior PROs on multivariable regression modeling (ie, being White, being nonsyndromic, having employment, and having better left ventricular function; P < 0.05), asymptomatic status (functional class I) was the variable associated with the greatest number of QOL and HS measures (P < 0.001).

CONCLUSIONS

Strategies to improve TOF outcomes should consider PROs alongside conventional clinical variables. Factors associated with poorer PROs represent opportunities to intervene to improve the lives of patients with TOF.

The multidisciplinary management of a mechanical mitral valve thrombosis in pregnancy: a case report and review of the literature

Background

The management of anticoagulation for mechanical heart valves during pregnancy poses a unique challenge. Mechanical valve thrombosis is a devastating complication for which surgery is often the treatment of choice. However, cardiac surgery for prosthetic valve dysfunction in pregnant patients confers a high risk of maternofetal morbidity and mortality.

Case summary

A 39-year-old woman in her first pregnancy at 30 weeks gestation presented to hospital with a mechanical mitral valve thrombosis despite therapeutic anticoagulation with low-molecular-weight heparin. She underwent an emergent caesarean section followed immediately by a bioprosthetic mitral valve replacement. This occurred after careful planning and organization on the part of a large multidisciplinary team.

Discussion

A proactive, rather than reactive, approach to the surgical management of a mechanical valve thrombosis in pregnancy will maximize the chances of successful maternal and fetal outcomes.

Canadian Cardiovascular Society 2022 Guidelines for Cardiovascular Interventions in Adults With Congenital Heart Disease

Interventions in adults with congenital heart disease (ACHD) focus on surgical and percutaneous interventions in light of rapidly evolving ACHD clinical practice. To bring rigour to our process and amplify the cumulative nature of evidence ACHD care we used the ADAPTE process; we systematically adjudicated, updated, and adapted existing guidelines by Canadian, American, and European cardiac societies from 2010 to 2020. We applied this to interventions related to right and left ventricular outflow obstruction, tetralogy of Fallot, coarctation, aortopathy associated with bicuspid aortic valve, atrioventricular canal defects, Ebstein anomaly, complete and congenitally corrected transposition, and patients with the Fontan operation. In addition to tables indexed to evidence, clinical flow diagrams are included for each lesion to facilitate a practical approach to clinical decision-making. Excluded are recommendations for pacemakers, defibrillators, and arrhythmia-directed interventions covered in separate designated documents. Similarly, where overlap occurs with other guidelines for valvular interventions, reference is made to parallel publications. There is a paucity of high-level quality of evidence in the form of randomized clinical trials to support guidelines in ACHD. We accounted for this in the wording of the strength of recommendations put forth by our national and international experts. As data grow on long-term follow-up, we expect that the evidence driving clinical practice will become increasingly granular. These recommendations are meant to be used to guide dialogue between clinicians, interventional cardiologists, surgeons, and patients making complex decisions relative to ACHD interventions.

Neurocognitive disorders amongst patients with congenital heart disease undergoing procedures in childhood

BACKGROUND

Amongst children with congenital heart disease (CHD), earlier age of repair improves cardiovascular outcomes. The effects of early intervention on neurodevelopment remains unclear. We assessed the association between early life repair, cardiopulmonary bypass (CPB) and the incidence of neurocognitive disorders (NCD) amongst CHD patients.

METHODS

We created two retrospective cohorts from the Quebec CHD Database; with data from 1988 to 2010. Complexity of reparative procedures for CHD lesions were used as the proxy of CPB exposure with more complex procedure means longer exposure to CPB. Study Population 1 included pediatric patients with a single reparative procedure and compared patients with complex (long CBP) versus isolated shunt (short CBP) lesions. To assess the effects of CPB alone in Study Population 2 we compared patients with isolated atrial septal defects (ASD) who had surgical (short CBP) versus percutaneous (no CBP) repairs. The primary endpoint for both cohorts was development of an NCD.

RESULTS

In Study population 1, 1174 patients underwent complex surgical repair and 1620 had a shunt closure. The incidence of NCDs was 2.45/100 person-years in the complex surgery group, and 2.08/100 person-years in the shunt closure group. The following were associated with increased risk of developing a NCD: surgical complexity (Hazard Ratio [HR] = 1.20, 95% Confidence Interval [CI]: 1.01-1.42), younger age at intervention (AAI) (HR = 1.20, 95% CI: 1.16-1.25), male sex (HR = 1.91, 95% CI: 1.61-2.27), and later calendar year at intervention (HR = 1.06, 95% CI: 1.04-1.07). Study population 2 had 527 isolated ASD patients; 202 underwent surgical repair and 325 had percutaneous closure. The incidence of NCDs was not statistically different between groups. Male sex (HR = 1.77, 95% CI: 1.08-2.89) and younger AAI (HR = 1.15, 95% CI: 1.06-1.25) were associated with increased NCD risk.

CONCLUSION

Increased surgical complexity, male sex and younger AAI were associated with increased risk of NCDs in pediatric CHD patients. Surveillance protocols should be considered to identify NCDs in CHD patients after cardiac intervention.

Risk prediction models for heart failure admissions in adults with congenital heart disease

BACKGROUND

Heart failure (HF) is the leading cause of death in adult patients with congenital heart disease (ACHD). No risk prediction model exists for HF hospitalization (HFH) for ACHD patients. We aimed to develop a clinically relevant one-year risk prediction system to identify ACHD patients at high risk for HFH.

METHODS

Data source was the Quebec CHD Database. A retrospective cohort including all ACHD patients aged 18-64 (1995-2010) was constructed for assessing the cumulative risk of HFH adjusting for competing risk of death. To identify one-year predictors of incident HFH, multivariable logistic regressions were employed to a nested case-control sample of all ACHD patients aged 18-64 in 2009. The final model was used to create a risk score system based on adjusted odds ratios.

RESULTS

The cohort included 29,991 ACHD patients followed for 648,457 person-years. The cumulative HFH risk by age 65 was 12.58%. The case-control sample comprised 26,420 subjects, of whom 189 had HFHs. Significant one-year predictors were age ≥ 50, male sex, CHD lesion severity, recent 12-month HFH history, pulmonary arterial hypertension, chronic kidney disease, coronary artery disease, systemic arterial hypertension, and diabetes mellitus. The created risk score ranged from 0 to 19. The corresponding HFH risk rose rapidly beyond a score of 8. The risk scoring system demonstrated excellent prediction performance.

CONCLUSIONS

One eighth of ACHD population experienced HFH before age 65. Age, sex, CHD lesion severity, recent 12-month HFH history, and comorbidities constructed a risk prediction model that successfully identified patients at high risk for HFH.

Cancer Risk in Congenital Heart Disease-What Is the Evidence?

As life expectancy in patients with congenital heart disease (CHD) has improved, the risk for developing noncardiac morbidities is increasing in adult patients with CHD (ACHD). Among these noncardiac complications, malignancies significantly contribute to the disease burden of ACHD patients. Epidemiologic studies of cancer risk in CHD patients are challenging because they require large numbers of patients, extended follow-up, detailed and validated clinical data, and appropriate reference populations. However, several observational studies suggest that cancer risks are significantly elevated in patients with CHD compared with the general population. CHD and cancer share genetic and environmental risk factors. An association with exposure to low-dose ionizing radiation secondary to medical therapeutic or diagnostic procedures has been reported. Patients with Down syndrome, as well as, to a lesser extent, deletion of 22q11.2 and renin-angiotensin system pathologies, may manifest both CHD and a predisposition to cancer. Such observations suggest that carcinogenesis and CHD may share a common basis in some cases. Finally, specific conditions, such as Fontan circulation and cyanotic CHD, may lead to multisystem consequences and subsequently to cancer. Nonetheless, there is currently no clear consensus regarding appropriate screening for cancer and surveillance modalities in CHD patients. Physicians caring for patients with CHD should be aware of this potential predisposition and meet screening recommendations for the general population fastidiously. An interdisciplinary and global approach is required to bridge the knowledge gap in this field.

Pulmonary Valve Replacement for Pulmonary Regurgitation in Adults With Tetralogy of Fallot: A Meta-analysis-A Report for the Writing Committee of the 2019 Update of the Canadian Cardiovascular Society Guidelines for the Management of Adults With Congenital Heart Disease

BACKGROUND

There is no systematic evidence review of the long-term results of surgical pulmonary valve replacement (PVR) dedicated to adults with repaired tetralogy of Fallot (rTOF) and pulmonary regurgitation.

METHODS

Our primary objective was to determine whether PVR reduced long-term mortality in adults with rTOF compared with conservative therapy. Secondary objectives were to determine the postoperative incidence rate of death, the changes in functional capacity and in right ventricular (RV) volumes and ejection fraction after PVR, and the postoperative incidence rate of sustained ventricular arrhythmias. A systematic search of multiple databases for studies was conducted without limits.

RESULTS

No eligible randomized controlled trial or cohort study compared outcomes of PVR and conservative therapy in adults with rTOF. We selected 10 cohort studies (total 657 patients) reporting secondary outcomes. After PVR, the pooled incidence rate of death was 1% per year (95% confidence interval [CI] 0-1% per year) and the pooled incidence rate of sustained ventricular arrhythmias was 1% per year (95% CI 1%-2% per year). PVR improved symptoms (odds ratio for postoperative New York Heart Association functional class > II 0.08, 95% CI 0.03-0.24). Indexed RV end-diastolic (-61.29 mL/m², -43.64 to -78.94 mL/m²) and end-systolic (-37.20 mL/m², -25.58 to -48.82 mL/m²) volumes decreased after PVR, but RV ejection fraction did not change (0.19%, -2.36% to 2.74%). The effect of PVR on RV volumes remained constant regardless of functional status.

CONCLUSION

Studies comparing PVR and conservative therapy exclusively in adults with rTOF are lacking. After PVR, the incidence rates of death and ventricular tachycardia are both 1 per 100 patient-years. Pooled analyses demonstrated an improved functional status and a reduction in RV volumes.

Exposure to Low-Dose Ionizing Radiation From Cardiac Procedures and Malignancy Risk in Adults With Congenital Heart Disease

Background:

Adults with congenital heart disease (CHD) are exposed to increasing amounts of low-dose ionizing radiation (LDIR) from cardiac procedures. Cancer prevalence in this population is higher than in the general population. This study estimates the association between LDIR exposure from cardiac procedures and incident cancer in adult patients with CHD.

Methods:

The study population derived from the Quebec Congenital Heart Disease Database. We measured cumulative numbers of LDIR-related cardiac procedures for each patient until 1 year before the time of cancer diagnosis or administrative censoring. To assess the association between LDIR exposure and cancer risk, we conducted a nested case-control study and matched cancer cases with controls on sex, CHD severity, birth year, and age.

Results:

The study included 24 833 adult patients with CHD aged 18 to 64 years from 1995 to 2009. In >250 791 person-years of follow-up, 602 cancer cases were observed (median age, 55.4 years). The cumulative incidence of cancer estimated up to 64 years of age was 15.3% (95% confidence interval [CI], 14.2–16.5). Cases had more LDIR-related cardiac procedures than controls (1410 versus 921 per 1000 adult patients with CHD, P <0.0001). Cumulative LDIR exposure was independently associated with cancer (odds ratio [OR], 1.08 per procedure; 95% CI, 1.04–1.13). Similar results were obtained by using dose estimates for LDIR exposure (OR, 1.10 per 10 mSv; 95% CI, 1.05–1.15) with a possible dose-related response. The effect measure was in the same direction, and the association was persistent for exposure from ≥6 procedures in all sensitivity analyses: after excluding most smoking-related cancer cases (OR, 1.10 per procedure; 95% CI, 1.05–1.16 and OR when exposure from ≥6 procedures, 3.08; 95% CI, 1.77–5.37), and after applying a 3-year lag period (OR, 1.09 per procedure; 95% CI, 1.03–1.14 and OR when exposure from ≥6 procedures: 2.58; 95% CI, 1.43–4.69).

Conclusions:

To our knowledge, this is the first large population-based study to analyze and document the association between LDIR-related cardiac procedures and incident cancer in the population of adults with CHD. Confirmations of these findings by prospective studies are needed to reinforce policy recommendations for radiation surveillance in patients with CHD where no regulation currently exists. Physicians ordering and performing cardiac imaging should ensure that exposure is as low as reasonably achievable without sacrificing quality of care.

Repeated blood transfusions: Identification of a novel culprit of early graft failure in children

BACKGROUND

The attrition of right ventricle to pulmonary artery (RV-PA) grafts has been attributed in part to the body's immunologic response. We hypothesized that antibodies developed through blood transfusion, directed against the grafts, may result in accelerated degeneration and the need for re-intervention.

METHODS

This is a population-based study of the province of Quebec. We included children born between January 1, 1987 to December 31, 2006 who were diagnosed with a cono-truncal anomaly and had an RV-PA graft. The patients were followed for transfusion exposure and RV-PA graft re-intervention. Time to re-intervention in those exposed versus non-exposed was analyzed using Cox regression. Analysis was done in two time periods, before and after the calendar year 2000, given the change in blood preparation in the province of Quebec.

RESULTS

There were 413 patients who met the inclusion criteria of a cono-truncal disorder. Of the whole study population, 69% received a blood transfusion. Cox regression analysis showed that among patients who had the initial graft performed (n=181) before year 2000, having 2 or more blood transfusion was associated with an nearly tripled risk of a re-intervention comparing to no blood transfusion (hazard ratio of 2.88; 95% confidence interval 1.05-7.91). In patients who had the initial graft performed after year 2000 (n=232), the associated risk increase was 7-fold (hazard ratio of 7.01; 95% confidence interval 3.06-16.02). Kaplan-Meier analyses confirmed the significant difference in the re-intervention free survival probabilities between those who received 2 or more blood product transfusion and those who did not as well: prior to year 2000 (67.9% vs. 88.0% at 5years, p=0.0201) as well as after year 2000 (39.7% vs. 82.8% at 5years, p<0.0001).

CONCLUSION

In this population-based analysis, repeated blood product transfusion was associated with a significant increased risk of a need for RV-PA graft re-intervention. This data strongly suggest that repeated blood transfusion may adversely impact graft longevity.

183 In Vitro Generation and Characterization of Putative Primordial Germ Cells Derived from Induced Pluripotent Stem Cells in Cattle

Embryonic pluripotent stem cells (ESC) and induced pluripotent stem cells (iPSC) were reported capable of differentiating into primordial germ cell-like (PGCL) and functional gametes in vitro in the murine model (Hikabe et al. 2016 Nature 539, 299-303). The in vitro generation of primordial germ cells (PGC) and gametes from farm animals would greatly contribute to enhance animal production technologies and to the creation of adequate models for several disorders. The present study aimed at the generation of PGC in vitro (iPGC) from iPSC in cattle and their characterisation through pluripotency and germ cell markers. For that, bovine iPSC previously generated and characterised (Bressan et al. 2015 Reprod. Fertil. Dev. 27, 254) were submitted to in vitro differentiation into epiblast-like cells (EpiLC) and iPGC by the protocol adapted from mice (Hayashi et al. 2011 Cell 146, 519-532). The biPS cells were induced into EpiLC by culture in fibronectin-coated (16.7 µg mL−1) 6-well plates in N2B27 culture medium supplemented with 20 ng mL−1 activin A, 12 ng mL−1 basic fibroblast growth factor (bFGF), and 1% knockout serum replacement (KSR) for 48 h and further differentiated into iPGC by non-adherent culture (Agreewell plates, StemCell Technologies, Vancouver, BC, Canada) with GK15 medium (GMEM supplemented with 15% KSR, 0.1 mM nonessential amino acids, 1 mM sodium pyruvate, 0.1 mM 2-mercaptoethanol, 2 mm l-glutamine, and 1% antibiotics) in the presence of 500 ng mL−1 BMP4, 100 ng mL−1 SCF, 500 ng mL−1 BMP8b, and 50 ng mL−1 epidermal growth factor for 4 days. The cells were then characterised regarding morphology, detection of alkaline phosphatase, immunofluorescence for OCT4, DDX4, VASA, and c-Kit proteins, and transcripts of pluripotency-related genes OCT4 and SOX2, as well as of imprinted genes (H19, SNRPN) and imprinted-related (DNMT1, DNMT3B) genes were analysed through RT-qPCR and compared with constitutive genes GAPDH, NAT1, and ACTB. Alkaline phosphatase and immunofluorescence analysis were positive for all specific markers. Interestingly, although OCT4 and SOX2 expression was present in iPS, EpiLC, and iPGC, this last group presented greater OCT4 and lesser SOX2 transcript amounts compared with other groups, suggesting, as expected, that PGC are still pluripotent but may already be differentiating into germ-cell lineages. The expression of H19 was increased in iPGC, whereas the expression of SNRPN was decreased only in the fibroblast group, potentially indicating epigenetic reprogramming process in these cells. Expression of DNMT1 and DNMT3B was not different between pluripotent groups but subtly increased when compared with that in fibroblasts. The results obtained herein represent an important first step in the in vitro generation of PGC and gametes from domestic farm animals, an unprecedented and desirable tool for enhancing new reproductive technologies and providing new understanding of cellular reprogramming and pluripotent germ cell biology. Financially supported by FAPESP grants 2013/08135-2, 2013/13686-8, 2015/26818-5; CNPq 482163/2013-5.

Incidence, Predictors, and Mortality of Infective Endocarditis in Adults With Congenital Heart Disease Without Prosthetic Valves

Congenital heart disease (CHD) increases the risk of infective endocarditis (IE), though the lesion-specific risk and mortality are poorly defined. Using the population-based Quebec CHD database, we sought to describe the predictors of IE and to evaluate if IE was associated with mortality among adult CHD (ACHD) patients without prior valve replacement surgery. We extracted data on ACHD patients with IE and assessed the lesion-specific incidence of IE, risk factors for IE acquisition, and all-cause 1-year mortality. Among 29,866 ACHD patients, 285 (0.95%) developed IE during follow-up period of 378,901 patient-years, from 1988-2010. The highest and lowest lesion-specific incidences of IE were observed with left-sided lesions (1.61/1000 patient-years) and patent ductus arteriosus (0.24/1000 patient-years), respectively. The following predicted the risk of IE acquisition (odds ratio (OR), 95% confidence interval [CI]): cardiac surgery in the previous 6 months (9.07, 3.98-20.67), endocardial cushion defects (6.65, 3.84-11.53), left-sided lesions (5.11, 3.60-7.25), cyanosis at birth (4.82, 3.12-7.46), ventricular septal defect (2.81, 1.87-4.21), diabetes mellitus (1.65, 1.10-2.48), and recent medical interventions (12.52, 5.23-29.97). Twenty-five (8.77%) patients died within 1-year of IE diagnosis, a substantially elevated rate compared to patients without IE (OR 31.07, 95%CI 16.23-59.49). The risk of death following IE diagnosis was similarly elevated among patients with left-sided, cyanotic and other CHD lesions. In conclusion, the risk of IE in ACHD patients is lesion-specific and is greatest in the context of recent medical interventions. IE is associated with increased 1-year mortality, irrespective of broad CHD lesion grouping.

Magnetic-guided catheter ablation of twin AV nodal reentrant tachycardia in a patient with left atrial isomerism, interrupted inferior vena cana, and Kawashima-Fontan procedure

Twin AV nodal reentrant tachycardia most commonly occurs in patients with complex congenital heart disease who have two distinct AV nodes, His bundles, and non‐preexcited QRS morphologies. Catheter ablation of the weaker AV node may be hindered by anatomical complexities. In such cases, remote magnetic guidance offers a potentially effective solution.

Mesenchymal-like stem cells in canine ovary show high differentiation potential

OBJECTIVES

Recent studies have reported the existence of stem cells in ovarian tissue that show enhanced proliferative and differentiation potential compared to other adult tissues. Based on this evidence, we hypothesized that ovarian tissue contained mesenchymal-like stem cells (MSC) that could be isolated using a novel rapid plastic adhesion technique.

MATERIALS AND METHODS

We established MSC lines derived from ovarian and adipose tissue based on their ability to rapidly adhere to plastic culture dishes in the first 3 hours after plating and studied their potentiality in terms of molecular markers and differentiation capacity.

RESULTS

Morphological and kinetic properties of in vitro cultured ovarian MSC were similar to adipose-derived MSC, and both reached senescence after similar passage numbers. Ovarian-derived MSC expressed mesenchymal (CD90 and CD44) but not haematopoietic markers (CD34 and CD45), indicating similarity to adipose-derived MSC. Moreover, ovarian-derived MSC expressed NANOG, TERT, SOX2, OCT4 and showed extensive capacity to differentiate not only into adipogenic, osteogenic and chondrogenic tissue but also towards neurogenic and endodermal lineages and even precursors of primordial germ cells.

CONCLUSION

These results show for the first time the derivation of ovarian cells with the molecular properties of MSC as well as wide differentiation potential. Canine ovarian tissue is accessible, expandable, multipotent and has high plasticity, holding promise for applications in regenerative medicine.

Differentiation of equine induced pluripotent stem cells into a keratinocyte lineage

REASONS FOR PERFORMING STUDY

Skin trauma in horses often leads to the development of chronic nonhealing wounds that lack a keratinocyte cover, vital for healing. Reports in mouse and man confirm the possibility of generating functional keratinocytes from induced pluripotent stem cells (iPSC), thus presenting myriad potential applications for wound management or treatment of skin disease. Similarly, differentiation of equine iPSC (eiPSC) into a keratinocyte lineage should provide opportunities for the advancement of veterinary regenerative medicine.

OBJECTIVES

The purpose of this study was to develop an efficient method for the differentiation of eiPSC into a keratinocyte lineage. It was hypothesised that eiPSC can form differentiated keratinocytes (eiPSC-KC) comparable with primary equine keratinocytes (PEK) in their morphological and functional characteristics.

STUDY DESIGN

Experimental in vitro study.

METHODS

Equine iPSC established using a nonviral system were treated for 30 days with retinoic acid and bone morphogenetic protein-4 to induce directed differentiation into iPSC-KC. Temporospatial gene and protein expression by eiPSC-KC was measured at weekly intervals of differentiation and in response to calcium switch. Proliferative and migratory capacities of eiPSC-KC were compared with those of PEK.

RESULTS

Equine iPSC, upon directed differentiation, showed loss of pluripotency genes and progressive increase in pancytokeratin expression indicating ectodermal specification into keratinocytes. High differentiation efficiency was achieved, with 82.5% of eiPSC expressing keratin 14, a marker of epidermal-specific basal stem cells, after 30 days of directed differentiation. Moreover, the proliferative capacity of eiPSC-KC was superior, while the migratory capacity (measured as the ability to epithelise in vitro wounds) was comparable with that of PEK.

CONCLUSIONS

This proof of concept study suggests that eiPSC can successfully be differentiated into equine keratinocytes (eiPSC-KC) with features that are promising to the development of a stem cell-based skin construct, with the potential to regenerate lost or damaged skin.

331 ABNORMAL DNA METHYLATION PATTERNS AND ALLELE-SPECIFIC EXPRESSION OF IMPRINTED GENES IN BOVINE-INDUCED PLURIPOTENT STEM CELLS

Pluripotency reacquisition of somatic cells has been achieved through nuclear transfer (NT) to oocytes and, more recently, through induction with pluripotency-related factors (iPS cells). However, the epigenetic reprogramming process that enables the derivation of both NT-derived cloned animals and iPS cells is usually incomplete, leading to unhealthy offspring and poorly reprogrammed iPS cell lines. These unfavourable outcomes result in part from abnormal genome DNA methylation that leads to aberrant gene expression patterns. For instance, differentially methylated regions (DMR) and monoalleleic expression of imprinted genes, essential for normal cellular commitment and early development, are thought to be severely disturbed by reprogramming techniques. Indeed, H19 and SNRPN, imprinted genes, were disturbed in bovine NT-derived embryos and fetuses. Herein we investigated whether the DMR and parent-of-origin expression of the imprinted genes H19 and SNRPN are also perturbed in iPS lines. To analyse the DMR methylation patterns and allelic expression of H19 and SNRPN using parental-specific polymorphisms, we derived multiple clones of bovine iPS (biPS) cells from an interspecies (Bos indicus × Bos taurus) fetal fibroblast (bFF) using transduction with a policystronic lentivirus containing mouse Oct4, Sox2 c-Myc, and Klf-4 transcription factors. The DNA methylation patterns were evaluated by bisulfite sequencing and allelic expression by designing allele-specific PCR probes. We also quantified transcript expression by RT-PCR of H19, IGF2, SNRPN, OCT4, and NANOG by normalization with 3 housekeeping genes (GAPDH, NAT1, and ACTB). The biPS lines were characterised by a high nuclear : cytoplasmic ratio, dome-shaped colonies, positive AP activity, embryoid body formation, in vitro and in vivo (teratoma) formation, and expression of pluripotency-related genes. Compared to the bFF cells, methylation analyses of H19 showed partial hypomethylation of the paternal DMR on 1 iPS cell line and partial demethylation of the CTCF-binding region in the DMR of 2 other biPS lines, indicating abnormal demethylation of 3 out of the 4 biPS lines analysed. Methylation analyses of SNRPN revealed a partial hypomethylation in the maternal DMR and partial hypermethylation of the paternal DMR in 2 iPS lines. Gene expression analyses revealed the biallelic expression of H19 and decreased global expression of both H19 and IGF2, as well as the exclusively monoallelic paternal expression and significant increase in global expression of SNRPN. Interestingly, although OCT4 was substantially overexpressed in biPS lines, we identified a hypermethylation of the CG-rich region of the OCT4 exon 1. Endogenous NANOG expression was observed in 2 biPS clones. We conclude that imprinting errors are observed in biPS clones, suggesting that these epigenetic anomalies are related to the reprogramming process and could be directly responsible for the variable phenotypes and low success rates of both cloning and iPS derivation procedures.Financial support was from NSERC, FAPESP (13/13686-8, 11/08376-4, 57877-3/2008, 08.135-2/2013), CNPq (573754/2008-0, 482163/2013-5).

Specialized Adult Congenital Heart Disease Care

Background—

Clinical guidelines recommend specialized care for adult congenital heart disease (ACHD) patients. In reality, few patients receive such dedicated care. We sought to examine the impact of specialized care on ACHD patient mortality.

Methods and Results—

We examined referral rates to specialized ACHD centers and ACHD patient mortality rates between 1990 and 2005 in the population-based Quebec Congenital Heart Disease database (n=71 467). This period covers several years before and after the publication of guidelines endorsing specialized care for ACHD patients. A time-series design, based on Joinpoint and Poisson regression analyses, was used to assess the changes in annual referral and patient mortality rates. The association between specialized ACHD care and all-cause mortality was assessed in both case–control and cohort studies. The time-series analysis demonstrated a significant increase in referral rates to specialized ACHD centers in 1997 (rate ratio, +7.4%; 95% confidence interval [CI], +6.6% to +8.2%). In parallel, a significant reduction in expected ACHD patient mortality was observed after year 2000 (rate ratio, −5.0%;95% CI, −10.8% to −0.8%). In exploratory post hoc cohort and case–control analyses, specialized ACHD care was independently associated with reduced mortality (hazard ratio, 0.78; 95% CI, 0.65–0.94) and a reduced odds of death (adjusted odds ratio, 0.82; 95% CI, 0.08–0.97), respectively. This effect was predominantly driven by patients with severe congenital heart disease (hazard ratio, 0.38; 95% CI, 0.22–0.67).

Conclusions—

A significant increase in referrals to specialized ACHD centers followed the introduction of the clinical guidelines. Moreover, referral to specialized ACHD care was independently associated with a significant mortality reduction. Our findings support a model of specialized care for all ACHD patients.

Anatomical considerations for the development of a new transcatheter aortopulmonary shunt device in patients with severe pulmonary arterial hypertension

Abstract Morbidity from pulmonary arterial hypertension (PAH) ensues when the pulmonary pressure reaches suprasystemic levels. A transcatheter alternative to the Potts shunt would allow decompression of the right heart without the surgical risks. To aid development of a transcatheter aortopulmonary shunt (TAPS) device, we described the anatomic relationship between the left pulmonary artery (LPA) and the descending aorta (dAO) in adults with severe pulmonary hypertension. Adults with severe PAH (peak systolic pulmonary arterial pressure [PASP] ≥80 mmHg) who had computed tomography of the chest were enrolled. Measurements were taken on the axial plane at the level of the pulmonary artery bifurcation. Forty patients (male sex, 9 patients; median age ± standard deviation [SD], [Formula: see text] years; median PASP ± SD, [Formula: see text] mmHg) were identified. The mean distance (±SD) between the LPA and dAO was [Formula: see text] mm. The mean luminal dAO and LPA diameters (±SD) were [Formula: see text] mm and [Formula: see text] mm, respectively. The LPA and dAO approximated in 93% of patients, with 38% having aortic calcification at the contact site. The mean "landing zone" width and height (defining an area with distance <4 mm between the outer borders) of the two arteries were [Formula: see text] mm and [Formula: see text] mm, respectively, at a mean distance of [Formula: see text] mm from the main pulmonary artery bifurcation. This study shows that the landing zone is able to accommodate a TAPS device of up to 15 mm in diameter in the majority of patients with severe PAH.

Infective Endocarditis in Children With Congenital Heart Disease

Background—

The American Heart Association guidelines for prevention of infective endocarditis (IE) in 2007 reduced the groups of congenital heart disease (CHD) patients for whom antibiotic prophylaxis was indicated. The evidence base in CHD patients is limited. We sought to determine the risk of IE in children with CHD.

Methods and Results—

We performed a population-based analysis to determine the cumulative incidence and predictors of IE in children (0–18 years) with CHD by the use of the Quebec CHD Database from 1988 to 2010. In 47 518 children with CHD followed for 458 109 patient-years, 185 cases of IE were observed. Cumulative incidence of IE was estimated in the subset of 34 279 children with CHD followed since birth, in whom the risk of IE up to 18 years of age was 6.1/1000 children (95% confidence interval, 5.0–7.5). In a nested case-control analysis, the following CHD lesions were at highest risk of IE in comparison with atrial septal defects (adjusted rate ratio, 95% confidence interval): cyanotic CHD (6.44, 3.95–10.50), endocardial cushion defects (5.47, 2.89–10.36), and left-sided lesions (1.88, 1.01–3.49). Cardiac surgery within 6 months (5.34, 2.49–11.43) and an age of <3 years (3.53, 2.51–4.96; reference, ages 6–18) also conferred an elevated risk of IE.

Conclusions—

In a large population-based cohort of children with CHD, we documented the cumulative incidence of IE and associated factors. These findings help identify groups of patients who are at the highest risk of developing IE.

Developmental and epigenetic anomalies in cloned cattle

Many of the developmental anomalies observed in cloned animals are related to foetal and placental overgrowth, a phenomenon known as the 'large offspring syndrome' (LOS) in ruminants. It has been hypothesized that the epigenetic control of imprinted genes, that is, genes that are expressed in a parental-specific manner, is at the root of LOS. Our recent research has focused on understanding epigenetic alterations to imprinted genes that are associated with assisted reproductive technologies (ART), such as early embryo in vitro culture (IVC) and somatic cell nuclear transfer (SCNT) in cattle. We have sought and identified single nucleotide polymorphisms in Bos indicus DNA useful for the analysis of parental-specific alleles and their respective transcripts in tissues from hybrid embryos derived by crossing Bos indicus and Bos taurus cattle. By analysing differentially methylated regions (DMRs) of imprinted genes SNRPN, H19 and the IGF2R in cattle, we demonstrated that there is a generalized hypomethylation of the imprinted allele and the biallelic expression of embryos produced by SCNT when compared to the methylation patterns observed in vivo (artificially inseminated). Together, these results indicate that imprinting marks are erased during the reprogramming of the somatic cell nucleus during early development, indicating that such epigenetic anomalies may play a key role in mortality and morbidity of cloned animals.