Francis E. Smit

Evaluation of a tissue-engineered bovine pericardial patch in paediatric patients with congenital cardiac anomalies: initial experience with the ADAPT-treated CardioCel® patch

OBJECTIVES This study evaluated the safety, efficacy and clinical performance of the tissue-engineered ADAPT® bovine pericardial patch (ABPP) in paediatric patients with a range of congenital cardiac anomalies. METHODS In this single-centre, prospective, non-randomized clinical study, paediatric patients underwent surgery for insertion of the ABPP. Primary efficacy measures included early (<30 day) morbidity; incidence of device-related complications; haemodynamic performance derived from echocardiography assessment at 6- and 12-month follow-up and magnetic resonance imaging findings in 10 randomly selected patients at 12 months. Secondary measures included device-handling characteristics; shape and sizing characteristics and perioperative implant complications. The Aristotle complexity scoring system was used to score the complexity level of all surgical procedures. Patients completing the 12-month study were eligible to enter a long-term evaluation study. RESULTS Between April 2008 and September 2009, the ABPP was used in 30 paediatric patients. In the 30-day postoperative period, no graft-related morbidity was observed. In total, there were 5 deaths (2 in the 30-day postoperative period and 3 within the first 6 postoperative months). All deaths were deemed due to comorbid non-graft-related events. Echocardiography assessment at 6 and 12 months revealed intact anatomical and haemodynamically stable repairs without any visible calcification of the patch. Magnetic resonance imaging assessment in 10 patients at 12 months revealed no signs of calcification. Fishers exact test demonstrated that patients undergoing more complex, higher risk surgical repairs (Aristotle complexity score >8) were significantly more likely to die (P = 0.0055, 58% survival compared with 100% survival for less complex surgical repairs). In 19 patients, echocardiographic data were available at 18-36 months with no evidence of device calcification, infection, thromboembolic events or device failure. CONCLUSIONS This study demonstrates the safety and efficacy of this engineered bovine pericardial patch as a cardiovascular substitute for surgical repair of both simple and more complex congenital cardiac defects.

Cardiac surgery risk-stratification models.

Abstract Risk models are widely used to predict outcomes after cardiac surgery. Not only is risk modelling applied in the assessment of the relative impact of specific risk factors on surgical outcomes, but also in patient counselling, the selection of treatment options, comparison of postoperative results, and quality-improvement programmes. At least 19 risk-stratification models exist for open-heart surgery. The focus of risk models was originally on pre-operative prediction of mortality. However, major morbidity is in general more common than mortality and the ability to predict only operative mortality is not an adequate method of determining surgical outcome. Multiple intra- and postoperative variables have been excluded in the majority of models and the possible effect of their future inclusion remains to be seen. The unique patient population of sub-Saharan Africa requires a unique risk model that reflects the patient population and levels of care.

Cardiovascular Tissue Engineering: Where We Come From and Where Are We Now?

Tissue engineering was introduced by Vacanti and Langer in the 80’s, exploring the potential of this new technology starting with the well-known “human ear on the mouse back”. The goal is to create a substitute which supplies an individual therapy for patients with regeneration, remodeling and growth potential. The growth potential of these subjects is of special interest in congenital cardiac surgery, avoiding repeated interventions and surgery. Initial applications of tissue engineered created substitutes were relatively simple cardiovascular grafts seeded initially by end-differentiated autologous endothelial cells. Important data were collected from these initial clinical autologous endothelial cell seeded grafts in peripheral and coronary vessel disease. After these initial successfully implantation bone marrow cell were used to seed patches and pulmonary conduits were implanted in patients. Driven by the positive results of tissue engineered material implanted under low pressure circumstances, first tissue engineered patches were implanted in the systemic circulation followed by the implantation of tissue engineered aortic heart valves. Tissue engineering is an extreme dynamic technology with continuously modifications and improvements to optimize clinical products. New technologies are unified and so this has also be done with tissue engineering and new application features, so called transcatheter valve intervention. First studies are initiated to apply tissue engineered heart valves with this new transcatheter delivery system less invasive. Simultaneously studies have been started on tissue engineering of so-called whole organs since organ transplantation is restricted due to donor shortage and tissue engineering could overcome this problem. Initial studies of whole heart engineering in the rat model are promising and larger size models are initiated.

Cardiology–cardiothoracic subspeciality training in South Africa : a position paper of the South Africa Heart Association

Abstract Over the past decades, South Africa has undergone rapid demographic changes, which have led to marked increases in specific cardiac disease categories, such as rheumatic heart disease (now predominantly presenting in young adults with advanced and symptomatic disease) and coronary artery disease (with rapidly increasing prevalence in middle age). The lack of screening facilities, delayed diagnosis and inadequate care at primary, secondary and tertiary levels have led to a large burden of patients with heart failure. This leads to suffering of the patients and substantial costs to society and the healthcare system. In this position paper, the South African Heart Association (SA Heart) National Council members have summarised the current state of cardiology, cardiothoracic surgery and paediatric cardiology reigning in South Africa. Our report demonstrates that there has been minimal change in the number of successfully qualified specialists over the last decade and, therefore, a de facto decline per capita. We summarise the major gaps in training and possible interventions to transform the healthcare system, dealing with the colliding epidemic of communicable disease and the rapidly expanding epidemic of non-communicable disease, including cardiac disease.

Bio-artificial heart as ultimate treatment of end-stage heart failure.

End-stage heart failure is a major health problem, but implementation of guidelines and optimizing medical therapy for this devastating disease should decrease mortality. If optimal conservative therapy is no longer sufficient, a mechanical support system may be required as final destination therapy or as bridge-to-transplant. Since the first heart transplantation in 1967, this therapy has become the criterion standard for end-stage heart failure, but is limited due to organ shortage. Tissue engineering could help overcome this limitation and provide regeneration, remodeling, and growth potential. This so-called bio-artificial heart would be available, created by a decellularized extracellular matrix and seeded with in vitro proliferated autologous cardiovascular cells. Results of the first experimental studies have been promising, but numerous challenges must be met before this procedure will be available.

The use of small stents to delay surgical intervention in very young children with critical congenital heart disease

Introduction: Surgery in very young children with critical obstructive congenital heart disease has a high morbidity and mortality. The aim of this study was to determine whether the use of small stents is feasible and if it could delay surgery. Materials and methods: Nineteen children were included in a retrospective review spanning 7 years. Patients were included in circumstances where surgery needed to be delayed and the use of a small stent could alleviate the underlying obstruction. Results: All attempts at stenting were successful (100%). Indications were diverse and included: aortic obstruction (n=9), right ventricular outfl ow tract obstruction (n=3), systemic-to-pulmonary artery shunt occlusion (n=5), infradiaphragmatic pulmonary vein obstruction (n=1) and salvage of a discontinuous left pulmonary artery (n=1). Reasons patients were not fi t for surgical intervention included: low weight (n=4), poor general clinical condition (n=12), surgical technical diffi culty (n=2) and unavailability of a critical care bed (n=1). Median age and weight at procedure was 4.6 months (range: 0.1 - 18.3) and 4.5kg (range: 1.7 - 9.5), respectively. Pressure gradients and saturations showed signifi cant improvement post stenting. Periprocedural complications were few (n=3) and there were no fatalities. Last follow-up was at a median of 7.8 months (range: 0.1 -9.0) post initial procedure. Nine cases proceeded to corrective surgery. Surgery was delayed by a median 13.5 months (range: 0.3 - 69.0 months) and weight increased to a median of 10.3kg (p<0.001). Five cases demised at a median of 73 days (range: 1 - 422) post initial stent placement, most at home secondary to unknown causes. Four patients remain in follow-up. One patient was lost to follow-up. Conclusion: The placement of stents in small, ill children is feasible. It immediately relieves the obstruction and improves the general clinical condition. Surgery can be delayed for weeks or months, thus giving the opportunity for somatic growth.

The prevalence of rheumatic heart disease among Grade 10 - 12 learners in the Free State and Northern Cape – Preliminary results of the Wheels-of-Hope Outreach Programme

An outreach programme was initiated to echocardiographically screen Grade 10 - 12 learners, in Central South Africa, for rheumatic heart disease (RHD). Preliminary results, after the screening of 1 015 learners, identifi ed 102 abnormal echocardiograms. The abnormal echocardiograms were reviewed by an echocardiographer and paediatric cardiologist team and 14 pathological conditions were confi rmed in 13 patients. The abnormalities included RHD (n=5), pericardial effusion (n=2), left ventricular hypertrophy (n=2), mitral valve prolapse (n=3), ventricle septal defect (VSD) (n=1) and sub-aorta stenosis (n=1). The benchmark study by McClaren, et al. conducted in Soweto in 1972 (n=12 050, age 2 - 18 years) showed an overall RHD prevalence of 6.9 per 1 000 and 12.2 per 1 000 in the 15 - 18 year old bracket. The highest incidence (19.2/100) was found in Grade 7 learners (age not defined). The preliminary result of this study is 4.9 RHD cases per 1 000 in Grade 10 - 12 learners. This fi nding may indicate an actual decline in the prevalence of RHD in Central South Africa.

Twenty Years of Adult Congenital Heart Surgery: A Single-Center African Experience.

Background: Lack of data exists on the surgical management of adult congenital heart disease on the African continent. This study was undertaken to describe the clinical profile and surgical outcome of adult patients with congenital heart disease undergoing surgery in a single-center African study population. Methods: A retrospective medical chart review of consecutive adult patients (≥18 years) undergoing congenital heart surgery between October 1995 and December 2015 at our institution was undertaken. We described cardiac diagnosis, diagnostic complexity, risk profile, and surgical morbidity and mortality. Results: Data were collected of 233 surgical procedures performed in 219 patients (45.6% males). The most common diagnostic category was septal defects (41.2%), followed by right heart lesions (17.2%), left heart lesions (12.4%), thoracic arteries (9.0%), and conduit failure (6.9%). Twenty-four percent of patients presented in functional class III or IV, and 46% of patients met the criteria for the simple Bethesda diagnostic class. Preoperative risk factors were identified in 19.8% of patients. Corrective surgery was performed in 71.7% of cases, reoperative surgery in 27.6%, and palliative surgery in 0.8%. Right ventricle to pulmonary artery conduit placement comprised 53.1% of reoperations. The overall hospital mortality was 1.7%. Postoperative complications occurred in 26.3% of cases. Conclusions: This study presents a detailed description of this emerging population in a developing world context. Our outcomes data suggest that adult congenital heart disease surgery is feasible in a Southern African tertiary referral center with low operative mortality and acceptable morbidity.

Percutaneous closure of ventricular septal defects in childhood

Ventricular septal defect is the most common congenital cardiac lesion. Surgery was, until recently, the only modality of treatment available. Since the first percutaneous closure was attempted, new devices have been developed and used to close these defects. The procedure is safe and effective if the defects are selected correctly with closure being achieved in more than 90% of patients. Morbidity and mortality are acceptable and comparable to surgery. However, percutaneous ventricular septal defect closure is difficult, technically challenging and should only be attempted in units with adequate experience, equipment and support.

Transcutanous aortic valve replacement with Medtronic CoreValve in a publicprivate partnership hospital complex

Objective: The aim of this study was to assess the initial experience of transcutaneous aortic valve implantation (TAVI) in a high risk aortic stenosis population not suitable for conventional surgical valve replacement. Background: No data exist for TAVI with Medtronic CoreValve in South Africa and especially not in a public private partnership hospital complex. Methods: Retrospective data regarding severe aortic stenosis evaluation, risk stratifi cation and management were evaluated over a 24 month period. Results: A total of 106 patients were evaluated of whom 17 were accepted for surgical valve replacement (SVR) while TAVI was attempted in 25. The CoreValve was successfully implanted in 96% (24/25) of the cases. No procedural or peri-procedural deaths occurred. Three patients required permanent pacemaker insertion in the peri-procedural period and 2 patients had vascular access complications requiring blood transfusion only. Median hospital stay was 3.7days (range: 2 - 7). Aortic valve gradient showed a signifi cant reduction after valve implantation, which was sustained during follow-up (p<0.001). NYHA class symptomatology also improved from a median of 3.3 to 1.0 (p<0.001). During follow-up there were 4 late deaths, not related to the procedure, occurring after 78 to 193 days. Average cost for private and government patients were R268 000.00 and R163 000.00 respectively. Conclusions: The CoreValve can be implanted with a high success rate. Short term mortality and morbidity are acceptable. Signifi cant symptomatic improvement is gained at follow-up. The fi nancial implications are important.