The Technological Basis of a Balloon-Expandable TAVR System: Non-occlusive Deployment, Anchorage in the Absence of Calcification and Polymer Leaflets.

Leaflet durability and costs restrict contemporary trans-catheter aortic valve replacement (TAVR) largely to elderly patients in affluent countries. TAVR that are easily deployable, avoid secondary procedures and are also suitable for younger patients and non-calcific aortic regurgitation (AR) would significantly expand their global reach. Recognizing the reduced need for post-implantation pacemakers in balloon-expandable (BE) TAVR and the recent advances with potentially superior leaflet materials, a trans-catheter BE-system was developed that allows tactile, non-occlusive deployment without rapid pacing, direct attachment of both bioprosthetic and polymer leaflets onto a shape-stabilized scallop and anchorage achieved by plastic deformation even in the absence of calcification. Three sizes were developed from nickel-cobalt-chromium MP35N alloy tubes: Small/23 mm, Medium/26 mm and Large/29 mm. Crimp-diameters of valves with both bioprosthetic (sandwich-crosslinked decellularized pericardium) and polymer leaflets (triblock polyurethane combining siloxane and carbonate segments) match those of modern clinically used BE TAVR. Balloon expansion favors the wing-structures of the stent thereby creating supra-annular anchors whose diameter exceeds the outer diameter at the waist level by a quarter. In the pulse duplicator, polymer and bioprosthetic TAVR showed equivalent fluid dynamics with excellent EOA, pressure gradients and regurgitation volumes. Post-deployment fatigue resistance surpassed ISO requirements. The radial force of the helical deployment balloon at different filling pressures resulted in a fully developed anchorage profile of the valves from two thirds of their maximum deployment diameter onwards. By combining a unique balloon-expandable TAVR system that also caters for non-calcific AR with polymer leaflets, a powerful, potentially disruptive technology for heart valve disease has been incorporated into a TAVR that addresses global needs. While fulfilling key prerequisites for expanding the scope of TAVR to the vast number of patients of low- to middle income countries living with rheumatic heart disease the system may eventually also bring hope to patients of high-income countries presently excluded from TAVR for being too young.

Experience of cardiac implantable electronic device lead removal from a South African tertiary referral centre.

BACKGROUND: The rate of cardiac implantable electronic device (CIED) implantation in low- and middle-income countries is increasing. Patients recieving these devices are frequently older and with multiple co-morbidities, which may later lead to complications requiring CIED removal. CIED removals are associated with life-threatening complications. However, high sucesss rates are reported in high-income countries. The purpose of this study was to report on the experience of CIED removal in a resource-constrained setting. METHODS: In this retrospective study, we included consecutive adult patients admitted to Groote Schuur Hospital and the University of Cape Town Private Academic Hospital for CIED removal from 1 January 2008 to 31 December 2019. RESULTS: During the study period, 53 patients underwent CIED removal (26 extractions and 27 explants). The patients had a mean (standard deviation) age of 59.1 (16.0) years. A history of systemic hypertension was present in 50.9% of patients, diabetes mellitus in 30.2% and dilated cardiomyopathy in 47.2%. Complete heart block was the leading indication for CIED implantation (37.7%), and device infection was the leading indication for removal (69.2%). CIEDs were removed after a median (interquantile range) of 243 (53-831) days. There were 40 leads extracted and 35 explants. Lead extractions were perfomed in the cardiac catheterisation laboratory under general anaesthesia via a percutaneous transvenous superior approach. There was one major and one minor complication related to lead extraction. CONCLUSIONS: CIED infections were the primary indication for CIED removal in a tertiary referral centre in South Africa. Despite being a low-volume centre, we report a high percutaneous transvenous extraction success rate with low complication rate; results which are comparable to high-volume centres.

Poorly suited heart valve prostheses heighten the plight of patients with rheumatic heart disease.

Rheumatic heart disease (RHD) still affects more patients globally than degenerative valve disease. The vast majority of these patients live in low- to middle-income countries. Once symptomatic, they will need heart valve surgery. Unfortunately, prosthetic valves perform poorly in these patients given their young age, the high incidence of multi-valve disease, late diagnoses and often challenging socio-economic circumstances. Notwithstanding the fact that better valve designs would ideally be available, ill-informed decision making processes between bioprosthetic and mechanical valves are contributing to the poor results. In the absence of multicentred, randomised clinical trials, comparing the current generations of bioprostheses with mechanical valves across all age groups Western guidelines tend to be uncritically applied. As a consequence, mechanical valves are being implanted into patients who are often not able to deal with anticoagulation while bioprosthetic valves may be overly shunned for fear of reoperations. Almost sixty years after the advent of cardiac surgery heart valve prostheses have eventually undergone improvements and several potentially disruptive developments are on the horizon. Until they materialise, however, choices between contemporary valve prostheses need to be made on the basis of individual risk and life-expectancy rather than an uncritical implementation of guidelines that were derived for very different patients and under distinctly different conditions. Given the fast expansion of cardiac surgery in middle-income countries and a growing number of independently operating centres in low-income countries a critical appraisal of facts underlying the choice of heart valve prostheses for patients with RHD seems opportune.

Transesophageal echocardiography in minimally invasive cardiac surgery.

PURPOSE OF REVIEW: Transesophageal echocardiography (TEE) has made its way into the cardiac surgery realm and spurred the development of many interventions. In the domain of minimally invasive cardiac surgery (MICS), TEE has become central to reducing cardiovascular complications. RECENT FINDINGS: Real-time three-dimensional TEE is a key contributor to the safe and precise deployment of the PASCAL mitral valve repair system, which is showing great potential in ongoing studies. The current data on outcomes of transcatheter aortic valve replacement show that preprocedural three-dimensional TEE and multidetector computed tomography (CT) perform similarly in aortic root assessment. Three-dimensional color Doppler TEE has been suggested to be more appropriate in quantifying residual mitral regurgitation and evaluating the success of surgical or percutaneous closure. A three-dimensional TEE-derived aortomitral angle may be valuable in predicting and detecting dynamic left ventricular outflow tract obstruction, thereby enhancing the safety of transcatheter mitral valve replacement. SUMMARY: Advanced imaging modalities are essential for the sustained growth of MICS, particularly with the evolution of novel transcatheter systems. These techniques rely on exceptional imaging quality at all stages of the perioperative period to modify surgical-risk and improve patient outcomes. TEE has the additional benefit of providing real-time information on intrathoracic structures to guide intraoperative management.

Preclinical evaluation of a transcatheter aortic valve replacement system for patients with rheumatic heart disease.

AIMS: Cardiac surgery in middle-income countries differs significantly from that in high-income countries regarding prevailing heart valve pathologies and access to cardiac surgery. Typically, rheumatic aortic regurgitation in the absence of calcification by far outweighs stenosis. As such, entirely different transcatheter aortic valve implantation (TAVI) concepts are required for these regions. The aim of the study was to evaluate the five-month performance of the SAT (Strait Access Technologies, Cape Town, South Africa) pericardial TAVI system in the orthotopic aortic position of juvenile sheep. METHODS AND RESULTS: A self-homing, non-occlusive balloon-expandable TAVI system comprising a hollow balloon, stabilising locator trunks, a scalloped CoCr stent with elevating anchorage arms and decellularised, sandwich-crosslinked pericardium was compared with control surgical valves (Edwards PERIMOUNT) in sheep. The implantation period was five months. The tactile placement of the TAVI valves was accomplished without the need for rapid pacing. At termination, no structural degeneration was observed in either group. The TAVIs were well healed with the stent struts largely embedded in tissue. Correlating with sheep growth (weight gain of 40.4±13.0%) during the implantation period, mean transvalvular gradients increased from 3.08±1.95 mmHg to 8.50±5.38 mmHg (p=0.044) after five months. CONCLUSIONS: A single-stage, balloon-expandable, easy to place TAVI system with antigen-depleted and antigen-masked bioprosthetic leaflets promises to address the distinct needs of low- and middle-income countries with regard to TAVI better than conventional systems.

A truly non-occlusive stent-graft moulding balloon for thoracic endovascular aortic repair.

Endovascular treatment of thoracic aortic pathologies has recently progressed towards more proximal pathologies, including those of the aortic arch and ascending aorta where there is a higher risk for stent-graft migration during the deployment or the moulding procedure due to the beating and ejecting heart. Typical measures to prevent dislodgement of the balloon or the stent-graft during the procedure are rapid pacing or pharmacologically induced hypotension. We present a circular and fully non-occlusive stent-graft moulding balloon that does not require any reduction of cardiac output or hypotension during inflation, moulding and deflation of the balloon.

Isolated mechanical aortic valve replacement in rheumatic patients in a low- to middle-income country.

OBJECTIVE: Although the results of aortic valve replacement are well documented for industrialized countries, the outcome in patients with rheumatic aortic valve disease in low- to middle-income countries is less well explored. The aim of this study was to determine the long-term survival and clinical outcomes after isolated aortic valve replacement in patients with rheumatic heart disease in a Sub-Saharan country where follow-up of indigent patients is often challenging. METHODS: A retrospective review of 969 aortic valve replacements performed between 2003 and 2013 was conducted at Cape Town's Groote Schuur Hospital. Patients who underwent concomitant procedures (n = 664) or had nonrheumatic valve pathology (n = 185) were excluded. The mean age of the rheumatic cohort (n = 121) was 43.1 ± 11.6 years with a mean follow-up period of 6.14 ± 3.44 years. The primary end points were survival and valve-related complications. RESULTS: A 15% cardiac- or valve-related 10-year mortality after receiving a mechanical prosthesis corresponded with a significantly higher mortality rate than that of a matched population. Overall cumulative survival at 1, 5, and 10 years was 93.5% (87.0-96.9), 86.4% (78.4-91.8), and 78.1% (67.5-86.0), respectively, and the corresponding cumulative freedom from combined thromboembolism and bleeding was 94.4% (88.2-97.5), 87.4% (79.4-92.5), and 86.1% (77.9-91.6), respectively. CONCLUSIONS: In low- to middle-income countries, with their unique mix of indigent and "First World" patients, rheumatic heart disease still accounts for a significant proportion of patients requiring isolated aortic valve replacement. Although mechanical prostheses are often selected in these young adults, survival remains suboptimal. Major bleeding and thromboembolic events account for the majority (77%) of the reported valve-related complications.

Global Unmet Needs in Cardiac Surgery.

More than 6 billion people live outside industrialized countries and have insufficient access to cardiac surgery. Given the recently confirmed high prevailing mortality for rheumatic heart disease in many of these countries together with increasing numbers of patients needing interventions for lifestyle diseases due to an accelerating epidemiological transition, a significant need for cardiac surgery could be assumed. Yet, need estimates were largely based on extrapolated screening studies while true service levels remained unknown. A multi-author effort representing 16 high-, middle-, and low-income countries was undertaken to narrow the need assessment for cardiac surgery including rheumatic and lifestyle cardiac diseases as well as congenital heart disease on the basis of existing data deduction. Actual levels of cardiac surgery were determined in each of these countries on the basis of questionnaires, national databases, or annual reports of national societies. Need estimates range from 200 operations per million in low-income countries that are nonendemic for rheumatic heart disease to >1,000 operations per million in high-income countries representing the end of the epidemiological transition. Actually provided levels of cardiac surgery range from 0.5 per million in the assessed low- and lower-middle income countries (average 107 ± 113 per million; representing a population of 1.6 billion) to 500 in the upper-middle-income countries (average 270 ± 163 per million representing a population of 1.9 billion). By combining need estimates with the assessment of de facto provided levels of cardiac surgery, it emerged that a significant degree of underdelivery of often lifesaving open heart surgery does not only prevail in low-income countries but is also disturbingly high in middle-income countries.

Transcatheter valve with a hollow balloon for aortic valve insufficiency.

During the past decade transcatheter aortic valve implantation (TAVI) has revolutionized our approach to heart valve disease. Although largely applied to patients with calcific aortic valve stenosis, there is an unmet clinical need to also treat patients with aortic valve insufficiency in patients with non-calcific aortic valve disorders. The following Techno-College tutorial demonstrates our pre-clinical experience with a novel non-occlusive, self-homing TAVI system, developed with Strait Access Technologies, that we hope will improve outcomes for treatment of non-calcific aortic valve insufficiency.

Upper ministernotomy.

During the past 50 years, median sternotomy has been the gold standard approach in cardiac surgery with excellent long-term outcomes. However, since the 1990 s, minimally invasive cardiac surgery (MICS) has gained wide acceptance due to patient and economic demand. The advantages include less surgical trauma, less bleeding, less wound infections, less pain and faster recovery of the patients. One of these MICS approaches is the J-shaped upper ministernotomy which results in favourable long-term outcomes even in elderly and redo patients when compared with conventional sternotomy. Owing to its similarity to a full midline sternotomy, it has become the most popular MICS approach besides a mini-thoracotomy. It is a safe and feasible access, but certain recognized principles are mandatory to minimize complications. After identification of the landmarks, the 5-cm skin incision is performed in the midline between the second and fourth rib. The third or fourth right intercostal space is located and dissected laterally off the sternum. After osteotomy, the pericardium is pulled up with stay sutures which allow excellent exposure. The surgical procedures are performed in a standard fashion with central cannulation. Continuous CO2 insufflation is used to minimize the risk of air embolism. Epicardial pacing wires are placed before the removal of the aortic cross-clamp and one chest tube is used. Sternal closure is achieved with three to five stainless steel wires. The pectoral muscle, subcutaneous tissue and skin are adapted with resorbable running sutures. When performed properly, complications are rare (conversion, bleeding and wound infection) and well manageable.

Safe, effective and durable epicardial left atrial appendage clip occlusion in patients with atrial fibrillation undergoing cardiac surgery: first long-term results from a prospective device trial.

OBJECTIVES: Atrial fibrillation (AF) is a significant risk factor for embolic stroke originating from the left atrial appendage (LAA). This is the first report of long-term safety and efficacy data on LAA closure using a novel epicardial LAA clip device in patients undergoing cardiac surgery. METHODS: Forty patients with AF were enrolled in this prospective 'first-in-man' trial. The inclusion criterion was elective cardiac surgery in adult patients with AF for which a concomitant ablation procedure was planned. Intraoperative transoesophageal echocardiography (TEE) was used to exclude LAA thrombus at baseline and evaluate LAA perfusion after the procedure, while computed tomography (CT) was used for serial imagery workup at baseline, 3-, 12-, 24- and 36-month follow-up. RESULTS: Early mortality was 10% due to non-device-related reasons, and thus 36 patients were included in the follow-up consisting of 1285 patient-days and mean duration of 3.5 ± 0.5 years. On CT, clips were found to be stable, showing no secondary dislocation 36 months after surgery. No intracardial thrombi were seen, none of the LAA was reperfused and in regard to LAA stump, none of the patients demonstrated a residual neck >1 cm. Apart from one unrelated transient ischaemic attack (TIA) that occurred 2 years after surgery in a patient with carotid plaque, no other strokes and/or neurological events demonstrated in any of the studied patients during follow-up. CONCLUSION: This is the first prospective trial in which concomitant epicardial LAA occlusion using this novel epicardial LAA clip device is 100% effective, safe and durable in the long term. Closure of the LAA by epicardial clipping is applicable to all-comers regardless of LAA morphology. Minimal access epicardial LAA clip closure may become an interesting therapeutic option for patients in AF who are not amenable to anticoagulation and/or catheter closure. Further data are necessary to establish LAA occlusion as a true and viable therapy for stroke prevention. CLINICAL TRIAL REGISTRATION: The trial is registered at www.ClinicalTrials.gov, reference: NCT00567515.

Transcatheter aortic valve implantation using anatomically oriented, marrow stromal cell-based, stented, tissue-engineered heart valves: technical considerations and implications for translational cell-based heart valve concepts.

OBJECTIVES: While transcatheter aortic valve implantation (TAVI) has rapidly evolved for the treatment of aortic valve disease, the currently used bioprostheses are prone to continuous calcific degeneration. Thus, autologous, cell-based, living, tissue-engineered heart valves (TEHVs) with regeneration potential have been suggested to overcome these limitations. We investigate the technical feasibility of combining the concept of TEHV with transapical implantation technology using a state-of-the-art transcatheter delivery system facilitating the exact anatomical position in the systemic circulation. METHODS: Trileaflet TEHVs fabricated from biodegradable synthetic scaffolds were sewn onto self-expanding Nitinol stents seeded with autologous marrow stromal cells, crimped and transapically delivered into the orthotopic aortic valve position of adult sheep (n = 4) using the JenaValve transapical TAVI System (JenaValve, Munich, Germany). Delivery, positioning and functionality were assessed by angiography and echocardiography before the TEHV underwent post-mortem gross examination. For three-dimensional reconstruction of the stent position of the anatomically oriented system, a computed tomography analysis was performed post-mortem. RESULTS: Anatomically oriented, transapical delivery of marrow stromal cell-based TEHV into the orthotopic aortic valve position was successful in all animals (n = 4), with a duration from cell harvest to TEHV implantation of 101 ± 6 min. Fluoroscopy and echocardiography displayed sufficient positioning, thereby entirely excluding the native leaflets. There were no signs of coronary obstruction. All TEHV tolerated the loading pressure of the systemic circulation and no acute ruptures occurred. Animals displayed intact and mobile leaflets with an adequate functionality. The mean transvalvular gradient was 7.8 ± 0.9 mmHg, and the mean effective orifice area was 1.73 ± 0.02 cm(2). Paravalvular leakage was present in two animals, and central aortic regurgitation due to a single-leaflet prolapse was detected in two, which was primarily related to the leaflet design. No stent dislocation, migration or affection of the mitral valve was observed. CONCLUSIONS: For the first time, we demonstrate the technical feasibility of a transapical TEHV delivery into the aortic valve position using a commercially available and clinically applied transapical implantation system that allows for exact anatomical positioning. Our data indicate that the combination of TEHV and a state-of-the-art transapical delivery system is feasible, representing an important step towards translational, transcatheter-based TEHV concepts.

Obesity should not deter a surgeon from selecting a minimally invasive approach for mitral valve surgery.

OBJECTIVE: Obesity is highly prevalent in modern patient populations. Several studies have published conflicting outcomes after minimally invasive surgery with regard to morbidity and mortality. Some instances consider obesity as a relative contraindication for this approach because of inadequate exposure of the surgical field. Our aim was to investigate the outcomes of minimally invasive mitral valve surgery through a right lateral minithoracotomy in patients with a body mass index (BMI) of 30 kg/m2 or greater. METHODS: We conducted a retrospective database review between January 1, 2009, and December 31, 2011. Preoperative, intraoperative, postoperative, and follow-up data of 225 consecutive patients were collected. RESULTS: The patients were stratified according to their BMI: 108 had a normal weight with a BMI of lower than 25 kg/m2 (18-24), 90 were overweight with a BMI of 25 to 29 kg/m2, and 27 were obese with a BMI of 30 kg/m2 (30-41) or greater. Statistical analysis showed significantly longer ventilation times in the obese group, whereas all other variables were similar. Survival, major adverse cardiac and cerebrovascular event-free survival, valve competency, and freedom from reoperation were also comparable. CONCLUSIONS: Our data suggest that obesity should not deter a surgeon from selecting a minimally invasive approach. Despite longer postoperative ventilation times, a BMI of 30 kg/m2 or greater does not influence short- and medium-term outcome. Obese patients may even benefit from this approach because it avoids the need for sternotomy and therefore reduces the risk for sternal wound infection.

Off-the-shelf human decellularized tissue-engineered heart valves in a non-human primate model.

Heart valve tissue engineering based on decellularized xenogenic or allogenic starter matrices has shown promising first clinical results. However, the availability of healthy homologous donor valves is limited and xenogenic materials are associated with infectious and immunologic risks. To address such limitations, biodegradable synthetic materials have been successfully used for the creation of living autologous tissue-engineered heart valves (TEHVs) in vitro. Since these classical tissue engineering technologies necessitate substantial infrastructure and logistics, we recently introduced decellularized TEHVs (dTEHVs), based on biodegradable synthetic materials and vascular-derived cells, and successfully created a potential off-the-shelf starter matrix for guided tissue regeneration. Here, we investigate the host repopulation capacity of such dTEHVs in a non-human primate model with up to 8 weeks follow-up. After minimally invasive delivery into the orthotopic pulmonary position, dTEHVs revealed mobile and thin leaflets after 8 weeks of follow-up. Furthermore, mild-moderate valvular insufficiency and relative leaflet shortening were detected. However, in comparison to the decellularized human native heart valve control - representing currently used homografts - dTEHVs showed remarkable rapid cellular repopulation. Given this substantial in situ remodeling capacity, these results suggest that human cell-derived bioengineered decellularized materials represent a promising and clinically relevant starter matrix for heart valve tissue engineering. These biomaterials may ultimately overcome the limitations of currently used valve replacements by providing homologous, non-immunogenic, off-the-shelf replacement constructs.

HEARTSTRING enabled no-touch proximal anastomosis for off-pump coronary artery bypass grafting: current evidence and technique.

Surgical revascularization remains the standard of care for many patients. Off-pump coronary artery bypass grafting (OPCAB) without cardiopulmonary bypass (CPB) has evolved during the past 20 years, and as such can significantly reduce the occurrence of neurological complications. While avoiding the aortic cross-clamping required in conventional on-pump techniques, OPCAB results in a lower incidence of stroke. However, clamp-related risk of stroke remains if partial or side-biting clamps are applied for proximal anastomoses. Others and we have demonstrated that no-touch 'anaortic' approaches avoiding any clamping during off-pump procedures via complete in situ grafting result in significantly reduced stroke rates when compared with partial clamping. Therefore, OPCAB in situ grafting has been proposed as the 'standard of care' to reduce neurological complications. However, this technique may not be applicable to for every patient as the use of free grafts (arterial or venous) requiring proximal anastomosis is often still necessary to achieve complete revascularization. In these situations, proximal anastomosis can be performed without a partial clamp by using the HEARTSTRING device, and over the last few years, considerable evidence has arisen supporting the impact of HEARTSTRING-enabled anastomosis to significantly minimize atheroembolism and neurological complications when compared with partial- or side-bite clamping. This paper provides a systematic overview and technical information about the combination of OPCAB and clampless strategies using the HEARTSTRING for proximal anastomosis to reduce stroke to levels reported for percutaneous coronary intervention.