Risks and Benefits of Using a Commercially Available Ventricular Assist Device for Failing Fontan Cavopulmonary Support: A Modeling Investigation

Fontan patients often develop circulatory failure and are in desperate need of a therapeutic solution. A blood pump surgically placed in the cavopulmonary pathway can substitute the function of the absent sub-pulmonary ventricle by generating a mild pressure boost. However, there is currently no commercially available device designed for the cavopulmonary application; and the risks and benefits of implanting a ventricular assist device (VAD), originally designed for the left ventricular application, on the right circulation of failing Fontan patients is not yet clear. Moreover, further research is needed to compare the hemodynamics between the two clinically-considered surgical configurations for cavopulmonary assist, with Full and inferior vena cava (IVC) support corresponding to the entire venous return or only the inferior venous return, respectively, being routed through the VAD. In this study, we used a numerical model of the failing Fontan physiology to evaluate the Fontan hemodynamic response to a left VAD during the IVC and Full support scenarios. We observed that during Full support, the VAD improved the cardiac output while maintaining blood pressures within safe ranges, and lowered the IVC pressure to \u3c15 mmHg; however, we found a potential risk of lung damage at higher pump speeds due to the excessive pulmonary pressure elevation. IVC support, on the other hand, did not benefit the hemodynamics in the patient cases simulated, resulting in the superior vena cava pressure increasing to an unsafe level of \u3e20 mmHg. The findings in this study may be helpful to surgeons for recognizing the risks of a cavopulmonary VAD and developing coherent clinical strategies for the implementation of cavopulmonary support

Risks and Benefits of Using a Commercially Available Ventricular Assist Device for Failing Fontan Cavopulmonary Support: A Modeling Investigation

Fontan patients often develop circulatory failure and are in desperate need of a therapeutic solution. A blood pump surgically placed in the cavopulmonary pathway can substitute the function of the absent sub-pulmonary ventricle by generating a mild pressure boost. However, there is currently no commercially available device designed for the cavopulmonary application; and the risks and benefits of implanting a ventricular assist device (VAD) originally designed for the left ventricular application on the right circulation of failing Fontan patients is not yet clear. Moreover, further research is needed to compare the hemodynamics between the two clinically-considered surgical configurations (Full Support and IVC Support) for cavopulmonary assist, with Full and IVC Support corresponding to the entire venous return or only the inferior venous return, respectively, being routed through the VAD. In this study, we used a numerical model of the failing Fontan physiology to evaluate the Fontan hemodynamic response to a left VAD during the IVC and Full supports. We observed that during the Full support the VAD improved the cardiac output while maintaining blood pressures within safe ranges, and lowered the IVC pressure to <15mmHg; however, we found a potential risk of lung damage at higher pump speeds due to the excessive pulmonary pressure elevation. IVC support the other hand, did not benefit the hemodynamics of the example failing Fontan patients, resulting in the superior vena cava pressure increasing to an unsafe level of >20 mmHg. The findings in this study may be helpful to surgeons for recognizing the risks of a cavopulmonary VAD and developing coherent clinical strategies for the implementation of cavopulmonary support

Target Flow-Pressure Operating Range for Designing a Failing Fontan Cavopulmonary Support Device

Fontan operation as the current standard of care for the palliation of single ventricle defects results in significant late complications. Using a mechanical circulatory device for the right circulation to serve the function of the missing subpulmonary ventricle could potentially stabilize the failing Fontan circulation. This study aims to elucidate the hydraulic operating regions that should be targeted for designing cavopulmonary blood pumps. By integrating numerical analysis and available clinical information, the interaction of the cavopulmonary support via the IVC and full assist configurations with a wide range of simulated adult failing scenarios was investigated; with IVC and full assist corresponding to the inferior venous return or the entire venous return, respectively, being routed through the device. We identified the desired hydraulic operating regions for a cavopulmonary assist device by clustering all head pressures and corresponding pump flows that result in hemodynamic improvement for each simulated failing Fontan physiology. Results show that IVC support can produce beneficial hemodynamics in only a small fraction of failing Fontan scenarios. Cavopulmonary assist device could increase cardiac index by 35% and decrease the inferior vena cava pressure by 45% depending on the patient\u27s pre-support hemodynamic state and surgical configuration of the cavopulmonary assist device (IVC or full support). The desired flow-pressure operating regions we identified can serve as the performance criteria for designing cavopulmonary assist devices as well as evaluating off-label use of commercially available left-side blood pumps for failing Fontan cavopulmonary support

The utility of computed tomographic angiography in a neonate on extracorporeal membrane oxygenation with extreme cyanosis after Blalock–Taussig shunt

A modified Blalock–Taussig shunt (mBTS) is often employed to provide pulmonary blood flow in neonates that are born with cyanotic congenital heart defects. However, acute shunt thrombosis can occur in the postoperative period, resulting in profound cyanosis. In this case report, we describe the utility of computed tomographic angiography (CTA) in the management of a neonate with extreme cyanosis after placement of a mBTS while on extracorporeal membrane oxygenation. Using CTA, several small clots were identified in the shunt as well as stenosis of the left pulmonary artery; neither of which were identified with echocardiography. The CTA allowed for quick identification of the disorder and helped direct prompt surgical intervention

Ethics Debate: When a Child's Heart is Failing

Filmed at the 2017 Annual STS Meeting in Houston, Texas, Dr Robert Sade of the Medical University of South Carolina moderates a debate on the appropriate course of care in the fictional case of a child who cannot be weaned from bypass following mitral valve surgery. Dr Minoo Kavarana of the Medical University of South Carolina and Dr Jessica Turnbull of Vanderbilt University in Tennessee present the cases for and against placing the child on the transplant waiting list, respectively.<div>Dr Sade chairs the Cardiothoracic Ethics Forum, which organized and presented this debate at the 2017 STS Meeting. The <a href="https://doi.org/10.1016/j.athoracsur.2017.06.041">transcript from the oral debate</a> was published in the October 2017 issue of <em>The Annals of Thoracic Surgery</em>.<br></div

Diversity in the Adult and Pediatric Heart Transplant Surgeon Workforce between 2000 and 2020

There is a paucity of literature evaluating trends in the demographic composition of the cardiothoracic surgery workforce. Using the United Network for Organ Sharing database, we retrospectively analyzed the changes in sex, race, and ethnicity of surgeons performing heart transplantations between 2000–2020. Surgeons performing heart transplantations for adult (≥18 years) and pediatric (<18 years) patients between 2000–2020 were identified and stratified by sex (male, female) and by race/ethnicity (non-Hispanic White, non-Hispanic Black, non-Hispanic Asian, Hispanic of any race). Between 2000–2020, the proportion of non-White and female cardiothoracic surgeons performing adult and pediatric heart transplantations increased. Nevertheless, there remains a lack of diversity in the workforce, particularly when compared to the general United States population

The Thoratec® CentriMag® for Pediatric Right Ventricular Failure

Acute right ventricular failure post heart transplantation in the pediatric population has not been well documented. Treatment using medical therapies including inotropes and nitric oxide are often inefficient for pediatric patients. Extracorporeal membrane oxygenation has been traditionally used in children until a long-term decision can be made. As a result of the emergence of smaller assist devices, pediatric practitioners now have more options available to treat this patient population. We describe the successful use of the Thoratec® CentriMag® in a pediatric patient posttransplantation with acute right ventricular failure