Anton Doubell

Epidemiology of pericardial effusions at a large academic hospital in South Africa.

The aim was to establish the prevalence of large pericardial effusions in the Western Cape Province of South Africa, and to determine the incidence of various types of effusions. A total of 233 patients presented with large pericardial effusions. Each patient underwent tests for HIV, sputum smear and culture, blood culture, blood biochemistry and serological testing. Tuberculous pericardial effusions were diagnosed according to pre-determined criteria. Eighty-four patients (36.1%) were found to be HIV positive; 81 of these (96.4 %) had tuberculous pericarditis. More than 65% of the study population was aged between 15 and 39 years. The prevalence of HIV amongst unemployed individuals was 49.0% compared to 30.0% amongst employed individuals. Tuberculous pericarditis was the most common cause of pericardial effusions (69.5%, n=162). It was concluded that tuberculosis (TB) is a leading cause of pericarditis in this province of South Africa. The prevalence of TB confounded by HIV co-infection is steadily increasing, burdening the health-care facilities.

Application of finite element analysis to the design of tissue leaflets for a percutaneous aortic valve

Percutaneous Aortic Valve (PAV) replacement is an attractive alternative to open heart surgery, especially for patients considered to be poor surgical candidates. Despite this, PAV replacement still has its limitations and associated risks. Bioprosthetic heart valves still have poor long-term durability due to calcification and mechanical failure. In addition, the implantation procedure often presents novel challenges, including damage to the expandable stents and bioprosthetic leaflets. In this study, a simplified version of Fungs elastic constitutive model for skin, developed by Sun and Sacks, was implemented using finite element analysis (FEA) and applied to the modelling of bovine and kangaroo pericardium. The FEA implementation was validated by simulating biaxial tests and by comparing the results with experimental data. Concepts for different PAV geometries were developed by incorporating valve design and performance parameters, along with stent constraints. The influence of effects such as different leaflet material, material orientation and abnormal valve dilation on the valve function was investigated. The stress distribution across the valve leaflet was also examined to determine the appropriate fibre direction for the leaflet. The simulated attachment forces were compared with suture tearing tests performed on the pericardium to evaluate suture density. It is concluded that kangaroo pericardium is suitable for PAV applications, and superior to bovine pericardium, due to its lower thickness and greater extensibility.

Transjugular Tricuspid Valve-in-Valve Replacement

The patient is a 38-year-old woman with rheumatic heart disease requiring surgery 21 years ago. She received a St. Jude mechanical prosthesis in the mitral position and a Carpentier-Edwards Perimount bioprosthesis (size 31) in the tricuspid position. Over the past 2 years, she has become progressively more short of breath with regular admissions for congestive heart failure despite medical treatment. Transthoracic echocardiography showed a severely dilated right atrium and a calcified tricuspid prosthesis with a mean gradient across the valve varying between 9 and 12 mm Hg (Figures 1 and 2). The mitral valve prosthesis functioned well. Figure 1. The continuous wave spectral Doppler of the degenerate tricuspid prosthesis before the procedure showing a profile of severe tricuspid stenosis with averaged (because of atrial fibrillation) peak and mean gradients of 12 and 9, respectively. Vmax indicates maximum flow velocity; Vmean, mean flow velocity; Pmax, maximal pressure gradient: Pmean, mean pressure gradient; Env Ti, duration of measured envelope; VTI, velocity time integral; HR, heart rate. Figure 2. Pressure half-time (PHT) measured over the tricuspid valve confirms severe tricuspid stenosis with a value of 461 ms. A decision was made to replace the tricuspid valve, but in consultation with the heart team, it was agreed that, given that the mitral valve prosthesis was functioning well, the risk of a second sternotomy to replace only the tricuspid valve was difficult to justify if an alternative option was available. Given the limited lifespan of a bioprosthesis in a young person, she would then require her third (and likely final) sternotomy at a young age. A joint decision was therefore made to offer the patient a minimally invasive tricuspid valve replacement by a transcatheter procedure. The risks of a transcatheter procedure were discussed with her, and she provided written informed consent. The option of a …

Large pericardial effusions due to systemic lupus erythematosus: a report of eight cases

The aim of this study was to describe the clinical, echocardiographic and laboratory characteristics of large pericardial effusions and cardiac tamponade secondary to systemic lupus erythematosus (SLE). An ongoing prospective study was conducted at Tygerberg Academic Hospital, South Africa between 1996 and 2002. All patients older than 13 years presenting with large pericardial effusions (.10 mm) requiring pericardiocentesis were included. Eight cases (out of 258) were diagnosed with SLE. The mean (SD) age was 29.5 (10.7) years. Common clinical features were Raynaud’s phenomenon, arthralgia and lupus nephritis class III/IV. Echocardiography showed Libman-Sacks endocarditis (LSE) in all the mitral valves. Two patients developed transient left ventricular dysfunction; both these patients had pancarditis. Typical serological findings included antinuclear antibodies, anti-double stranded DNA antibodies, low complement C4 levels and low C3 levels. CRP was elevated in six cases. Treatment consisted of oral steroids and complete drainage of the pericardial effusions. No repeat pericardial effusions or constrictive pericarditis developed amongst the survivors (3.1 years follow up). This study concludes that large pericardial effusions due to SLE are rare, and associated with nephritis, LSE and myocardial dysfunction. Treatment with steroids and complete drainage is associated with a good cardiac outcome.

The role of histopathology in establishing the diagnosis of tuberculous pericardial effusions in the presence of HIV

Aims : To establish the influence of human immunodeficiency virus (HIV) infection on the histopathological features of patients presenting with tuberculous pericarditis.

Pregnancy outcome in women with prosthetic heart valves

The pregnancy outcome of 59 pregnancies in 38 women with prosthetic heart valves, managed at a tertiary referral centre from 1989-98 were reviewed. Ten women underwent valve replacement during pregnancy. The main outcome measures were major maternal complications and perinatal outcome. The maternal mortality rate for pregnancies following valve replacement surgery was 6.1%, with a 21% pregnancy loss before viability and a perinatal loss of 8%. Major morbidity in this group was as follows: haemorrhage 29.8%, cardiac failure 12.8%, thromboembolism 8.5%, infective endocarditis 6.4% and valve thrombosis 4.3%. No maternal mortality occurred among those who underwent valve replacement during pregnancy but their perinatal loss was 25%. We conclude that although maternal mortality and morbidity rates in women with prosthetic heart valves who became pregnant were high, the perinatal outcome was good except for women who underwent valve replacement during pregnancy who experienced a high perinatal loss rate.The pregnancy outcome of 59 pregnancies in 38 women with prosthetic heart valves, managed at a tertiary referral centre from 1989-98 were reviewed. Ten women underwent valve replacement during pregnancy. The main outcome measures were major maternal complications and perinatal outcome. The maternal mortality rate for pregnancies following valve replacement surgery was 6·1%, with a 21% pregnancy loss before viability and a perinatal loss of 8%. Major morbidity in this group was as follows: haemorrhage 29·8%, cardiac failure 12·8%, thromboembolism 8·5%, infective endocarditis 6·4% and valve thrombosis 4·3%. No maternal mortality occurred among those who underwent valve replacement during pregnancy but their perinatal loss was 25%. We conclude that although maternal mortality and morbidity rates in women with prosthetic heart valves who became pregnant were high, the perinatal outcome was good except for women who underwent valve replacement during pregnancy who experienced a high perinatal loss rate.

Autonomous auscultation of the human heart employing a precordial electro-phonocardiogram and ensemble empirical mode decomposition

The research presented in this paper serves to provide a tool to autonomously screen for cardiovascular disease in the rural areas of Africa. With this tool, cardiovascular disease can potentially be detected in its initial stages, which is essential for effective treatment. The autonomous auscultation system proposed here utilizes recorded heart sounds and electrocardiogram signals to automatically distinguish between normal and abnormal heart conditions. Patients that are identified as abnormal by the system can then be referred to a specialist consultant, which will save a lot of unnecessary referrals. In this study, heart sound and electrocardiogram signals were recorded with the prototype precordial electro-phonocardiogram device, as part of a clinical study to screen patients for cardiovascular disease. These volunteers consisted of 28 patients with a diagnosed cardiovascular disease and, for control purposes, 34 persons diagnosed with healthy hearts. The proposed system employs wavelets to first denoise the recorded signals, which is then followed by segmentation of heart sounds. Frequency spectrum information was extracted as diagnostic features from the heart sounds by means of ensemble empirical mode decomposition and auto regressive modelling. The respective features were then classified with an ensemble artificial neural network. The performance of the autonomous auscultation system used in concert with the precordial electro-phonocardiogram prototype showed a sensitivity of 82% and a specificity of 88%. These results demonstrate the potential benefit of the precordial electro-phonocardiogram device and the developed autonomous auscultation software as a screening tool in a rural healthcare environment where large numbers of patients are often cared for by a small number of inexperienced medical personnel.

Autonomous detection of heart sound abnormalities using an auscultation jacket

This paper presents a study using an auscultation jacket with embedded electronic stethoscopes, and a software classification system capable of differentiating between normal and certain auscultatory abnormalities. The aim of the study is to demonstrate the potential of such a system for semi-automated diagnosis for underserved locations, for instance in rural areas or in developing countries where patients far outnumber the available medical personnel. Using an “auscultation jacket”, synchronous data was recorded at multiple chest locations on 31 healthy volunteers and 21 patients with heart pathologies. Electrocardiograms (ECGs) were also recorded simultaneously with phono cardiographic data. Features related to heart pathologies were extracted from the signals and used as input to a feed-forward artificial neural network. The system is able to classify between normal and certain abnormal heart sounds with a sensitivity of 84% and a specificity of 86%. Though the number of training and testing samples presented are limited, the system performed well in differentiating between normal and abnormal heart sounds in the given database of available recordings. The results of this study demonstrate the potential of such a system to be used as a fast and cost-effective screening tool for heart pathologies.

Clinical features and outcome of lupus myocarditis in the Western Cape, South Africa

Background African American ethnicity is independently associated with lupus myocarditis compared with other ethnic groups. In the mixed racial population of the Western Cape, South Africa, no data exists on the clinical features/outcome of lupus myocarditis. Objectives The objective of this study was to give a comprehensive description of the clinical features and outcome of acute lupus myocarditis in a mixed racial population. Methods Clinical records (between 2008 and 2014) of adult systemic lupus erythematosus (SLE) patients at a tertiary referral centre were retrospectively screened for a clinical and echocardiographic diagnosis of lupus myocarditis. Clinical features, laboratory results, management and outcome were described. Echocardiographic images stored in a digital archive were reanalysed including global and regional left ventricular function. A poor outcome was defined as lupus myocarditis related mortality or final left ventricular ejection fraction (LVEF) <40%. Results Twenty-eight of 457 lupus patients (6.1%) met inclusion criteria: 92.9% were female and 89.3% were of mixed racial origin. Fifty-three per cent of patients presented within three months after being diagnosed with SLE. Seventy-five per cent had severely active disease (SLE disease activity index ≥ 12) and 67.9% of patients had concomitant lupus nephritis. Laboratory results included: lymphopenia (69%) and an increased aRNP (61.5%). Treatment included corticosteroids (96%) and cyclophosphamide (75%); 14% of patients required additional immunosuppression including rituximab. Diastolic dysfunction and regional wall motion abnormalities occurred in > 90% of patients. LVEF improved from 35% to 47% (p = 0.023) and wall motion score from 1.88 to 1.5 (p = 0.017) following treatment. Overall mortality was high (12/28): five patients (17.9%) died due to lupus myocarditis (bimodal pattern). Patients who died of lupus myocarditis had a longer duration of SLE (p = 0.045) and a lower absolute lymphocyte count (p = 0.041) at diagnosis. LVEF at diagnosis was lower in patients who died of lupus myocarditis (p = 0.099) and in those with a persistent LVEF < 40% (n = 5; p = 0.046). Conclusions This is the largest reported series on lupus myocarditis. The mixed racial population had a similar prevalence, but higher mortality compared with other ethnic groups (internationally published literature). Patients typically presented with high SLE disease activity and the majority had concomitant lupus nephritis. Lymphopenia and low LVEF at presentation were of prognostic significance, associated with lupus myocarditis related mortality or a persistent LVEF < 40%.

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.