DFW

Rheumatic Heart Disease

The Need for Innovative Technologies

Approximately three decades ago, conditions such as hypertension and atherosclerotic heart diseases were rare in Africa, and communicable diseases were the major causes of death. However, over this same period, non-communicable diseases have shown a remarkable rise. Cardiovascular disease now surpasses HIV/AIDS, malaria and other enteric infections in the top causes of death, rising from the 6th to the 2nd leading cause of death in sub-Saharan Africa between 1990 and 2019. The underlying drivers have been marked increases in major risk factors, such as hypertension and diabetes, off-setting the substantial health gains made with communicable diseases. The underlying epidemiological shift has been heavily influenced by urbanization, reflected in the nutritional and activity transitions.

Rheumatic heart disease (RHD) is one of the most significant cardiovascular conditions in sub-Saharan Africa, especially seen in the densely-crowded townships.

It results from recurrent episodes of acute rheumatic fever following a streptococcal throat infection, thought to be an autoimmune-mediated response to interactions between the individual and certain components of the bacterial cell wall protein.

RHD is Estimated to Affect 40 Million People Worldwide

RHD is estimated to affect forty million people worldwide, the majority of whom are children and young adults in sub-Saharan Africa: around 400,000 die from RHD annually, with an average age at death in some regions as low as 28 years. RHD continues to take a heavy toll on many people in lower‐income countries, making it among the most neglected diseases relative to its burden worldwide. Until there is an effective vaccine for RHD prevention, the WHO suggests following a preventive approach associated with improved socioeconomic status of populations at risk, primary prevention, including treating patients with strep throat, secondary prevention of antibiotic prophylaxis among patients with previous rheumatic fever, and tertiary procedures, including medical/surgical treatment of symptomatic RHD. The evidence suggests that every seventh to tenth patient with RHD would need life- saving heart valve surgery.

It was the latter approach, concerning innovative surgical treatments for RHD patients, which stimulated the formation of the company Strait Access Technologies (SAT) in Cape Town, South Africa more than a decade ago. Several critical features of the disease and of the individuals that it affects, were the drivers of the vision of the two founders of the company, myself and Professor Zilla, then the Chris Barnard Professor of Cardiothoracic Surgery at the University of Cape Town. They were soon joined by Dr Deon Bezuidenhout (also of UCT). Their vision was that a combination of advanced principles of medical engineering and cardiovascular medicine could make a significant contribution to the preservation of quality of life for young people in many parts of Africa, and, indeed, in many other parts of the world.

Important Factors for SAT's Vision to Improve Quality of Life for Children and Young Adults in Sub-Saharan Africa with RDH

South Africa Township

The reality of limited access

to cardiac surgery in the developing world.

The principal clinical manifestations of RHD are seen with the valves of the heart. Progressive valvular disease commonly develops after a few episodes of acute rheumatic fever. Around 70% of children with rheumatic fever develop chronic valvular disease over the following decade or so, 15% of whom progress to severe disease states. According to the Cape Town Declaration on Access to Cardiac Surgery in the Developing World, the only effective treatment for RHD is open heart surgery; however, the availability of cardiac surgery facilities capable of performing the necessary surgical procedures for RHD patients in low-to-middle income countries is often very low, so that the people most at need of such surgery are unlikely to have the necessary access. Any new technology for treating RHD could not therefore rely on conventional cardiac surgical techniques.

TAVR,

Transcatheter Aortic Valve Replacement

The first open heart surgery procedures, using cardiopulmonary bypass, date back to the 1950’s, and heart valve replacements were initiated in the early 1960s. Successful as these were, they were largely confined to high-income countries; however, as individual longevity increased so did the number of patients in need of them, but often with co- morbidities that affected the ability to survive the bypass procedure. It became obvious that new approaches were needed and by the turn of the century, the minimally invasive techniques for accessing the aortic valve of the heart by means of a catheter threaded along a blood vessel, most commonly along the femoral artery starting in the groin area, was introduced; this technique was referred to as Transcatheter Aortic Valve Replacement (TAVR). As TAVR became more effective, in these highly resourced countries, it was apparent that they would have little impact in poorer, socio-economically deprived regions; such a major transformation would require simpler transcatheter procedures that could deploy valves cost-effectively without sophisticated healthcare infrastructure. Any new technology for treating RHD in low-to-middle income regions could not, therefore, rely on the then conventional TAVR technology.

The clinic-pathological barrier

we face regarding TAVR techniques in RHD patients.

There was one more highly significant clinic-pathological barrier to the use of the TAVR techniques for aortic valve conditions in those suffering from RHD. The majority of patients recommended for TAVR in high-income countries are elderly and exhibit aortic stenosis that involves a complex calcification process. The replacement valve can be anchored on the calcified tissue within the aortic annulus. However, in those with RHD, the pathology is not usually that of calcific stenosis, which restricts flow of blood through the valve, but of non-calcific regurgitation, which allows a significant degree of retrograde blood flow. Aortic valve regurgitation is a relative contraindication to TAVR because of the absence of calcification, which hinders valve anchoring and increases the risk of prosthesis embolization. Any new technology for treating non-calcific aortic regurgitation (the majority) could not, therefore, rely on the TAVR technology that had been developed for elderly aortic stenosis patients.

South Africa Township

The reality of limited access

to cardiac surgery in the developing world.

The principal clinical manifestations of RHD are seen with the valves of the heart. Progressive valvular disease commonly develops after a few episodes of acute rheumatic fever. Around 70% of children with rheumatic fever develop chronic valvular disease over the following decade or so, 15% of whom progress to severe disease states. According to the Cape Town Declaration on Access to Cardiac Surgery in the Developing World, the only effective treatment for RHD is open heart surgery; however, the availability of cardiac surgery facilities capable of performing the necessary surgical procedures for RHD patients in low-to-middle income countries is often very low, so that the people most at need of such surgery are unlikely to have the necessary access. Any new technology for treating RHD could not therefore rely on conventional cardiac surgical techniques.

TAVR,

Transcatheter Aortic Valve Replacement

The first open heart surgery procedures, using cardiopulmonary bypass, date back to the 1950’s, and heart valve replacements were initiated in the early 1960s. Successful as these were, they were largely confined to high-income countries; however, as individual longevity increased so did the number of patients in need of them, but often with co- morbidities that affected the ability to survive the bypass procedure. It became obvious that new approaches were needed and by the turn of the century, the minimally invasive techniques for accessing the aortic valve of the heart by means of a catheter threaded along a blood vessel, most commonly along the femoral artery starting in the groin area, was introduced; this technique was referred to as Transcatheter Aortic Valve Replacement (TAVR). As TAVR became more effective, in these highly resourced countries, it was apparent that they would have little impact in poorer, socio-economically deprived regions; such a major transformation would require simpler transcatheter procedures that could deploy valves cost-effectively without sophisticated healthcare infrastructure. Any new technology for treating RHD in low-to-middle income regions could not, therefore, rely on the then conventional TAVR technology.

The clinic-pathological barrier

we face regarding TAVR techniques in RHD patients.

There was one more highly significant clinic-pathological barrier to the use of the TAVR techniques for aortic valve conditions in those suffering from RHD. The majority of patients recommended for TAVR in high-income countries are elderly and exhibit aortic stenosis that involves a complex calcification process. The replacement valve can be anchored on the calcified tissue within the aortic annulus. However, in those with RHD, the pathology is not usually that of calcific stenosis, which restricts flow of blood through the valve, but of non-calcific regurgitation, which allows a significant degree of retrograde blood flow. Aortic valve regurgitation is a relative contraindication to TAVR because of the absence of calcification, which hinders valve anchoring and increases the risk of prosthesis embolization. Any new technology for treating non-calcific aortic regurgitation (the majority) could not, therefore, rely on the TAVR technology that had been developed for elderly aortic stenosis patients.

With these guiding principles in mind, the founders of SAT (later renamed SATH) recognized that several other important geo-political / socio-economic, clinical and technological factors had to be taken into account:

The Groote Schuur Hospital in Cape Town is where Professor Barnard carried out the world’s first human heart transplantation, and the current location of Strait Access Technologies.

Groote Schuur Hospital is a large, government-funded, teaching hospital situated on the slopes of Devil’s Peak in the city of Cape Town, South Africa. It was founded in 1938 and is famous for being the institution where the first human-to-human heart transplant took place, conducted by University of Cape Town-educated surgeon Christiaan Barnard on the patient Louis Washkansky.