1180
The Journal of Heart and Lung Transplantation, Vol 33, No 11, November 2014
days post-procedure is similar to that of a recent study that evaluated allosensitization much later after the NorwoodAG procedure and found that 56% were sensitized at median follow-up of 10.1 years.4 More importantly, almost all our sensitized Norwood-AG patients had very high PRA (HLA Class I or II antibody 450%) as compared with none in the Norwood-nonAG and hybrid groups. Mahle et al showed that patients with very high PRA has the highest risk of death after HTx.1 Although mortality was not significantly different between our study groups, this may become apparent in larger studies. The purpose of this study was to evaluate outcomes of alternative strategies in a group of patients with the highest risk of allosensitization and post-transplant mortality. Our results show that avoidance of allograft use at surgical palliation can lead to less allosensitization, less rejection and favorable posttransplant outcomes in infants with HLHS. Therefore, highrisk patients with HLHS, who are likely to require HTx early in life, may benefit from palliation with a hybrid procedure instead of a Norwood procedure as a bridge to transplant. Moreover, because many HLHS patients will eventually require HTx, aortic arch reconstruction with non-allograft material at time of Norwood palliation should be considered for standard risk patients as well.
Disclosure statement The authors have no conflicts of interest to disclose.
Virtual implantation evaluation of the total artificial heart and compatibility: Beyond standard fit criteria Ryan A. Moore, MD, Peace C. Madueme, MD, Angela Lorts, MD, David L.S. Morales, MD, and Michael D. Taylor, MD, PhD From the Cincinnati Children’s Hospital Medical Center, The Heart Institute, Cincinnati, Ohio
In the United States, children with end-stage heart failure listed for heart transplant face the highest waiting list mortality in transplant medicine.1 Mechanical circulatory support (MCS) devices have revolutionized advanced heart failure management by creating a durable bridge to transplant.2 A shift has occurred in the adult MCS population to intracorporeal MCS devices that allow for ambulatory care while awaiting transplantation.3 The future of pediatric MCS is the expansion of long-term ambulatory devices; however, the pediatric and small adult populations do not typically meet conservative intracorporeal device fit criteria, and poor post-operative outcomes related to device mismatch have been reported.4 The CardioWest temporary Total Artificial Heart (TAH-t; SynCardia Systems Inc, Tucson, AZ) is well suited for
C.I. was supported by the University of Washington Medical Student Research Training Program. The authors thank Yuk Law, MD, for critical reading of the manuscript.
Supplementary materials Supplementary materials associated with this article can be found in the online version at www.jhltonline.org.
References 1. Mahle W, Tresler M, Edens E, et al. Allosensitization and outcomes in pediatric heart transplantation. J Heart Lung Transplant 2011;30: 1221-7. 2. Shaddy R, Hunter D, Osborn K, et al. Prospective analysis of HLA immunogenicity of cryopreserved valved allografts used in pediatric heart surgery. Circulation 1996;94:1063-7. 3. Breinholt J, Hawkins J, Lambert L, et al. A prospective analysis of immunogenicity of cryopreserved nonvalved allografts used in pediatric heart surgery. Circulation 2000;102(suppl 3):III-179-82. 4. O’Connor M, Lind C, Tang X, et al. Persistence of anti-human leucocyte antibodies in congenital heart disease late after surgery using allograft and whole blood. J Heart Lung Transplant 2013;21:390-7. 5. Rossano J, Morales D, Zafar F, et al. Impact of antibodies against human leucocyte antigens on long-term outcome in pediatric heart transplant patients: an analysis of the United Network for Organ Sharing database. J Thorac Cardiovasc Surg 2010;140:694-9. 6. Laing B, Ross D, Meyer S, et al. Glutaraldehyde treatment of allograft tissue decreases allosensitization after the Norwood procedure. J Thorac Cardiovasc Surg 2010;139:1402-8.
certain pediatric and young adult heart failure patients with previously limited MCS options. The standard fit criteria includes a body surface area (BSA) of 1.7 m2 and an anteroposterior distance greater than 10 cm from the sternum to the 10th thoracic vertebra (T10).4 On the basis of these criteria, most pediatric and small adult patients are excluded from TAH-t placement. Innovative imaging techniques are necessary to improve eligibility for TAH-t placement in smaller patients; therefore, we developed a novel technique using virtual TAH-t implantation in pediatric and small adult patients to compare with standard fit criteria. Five patients (aged 12–34 years; BSA, 1.31–1.98 m2) identified as potential candidates for TAH-t as a bridge to cardiac transplantation underwent virtual implantation (Table 1). Detailed methods are available on the jhltonline. org Web site. Briefly, an accurately scaled 3-dimensional (3D) surface rendering of the TAH-t was placed within a 3D reconstruction of the chest to assess for proper fit. Device compression of pertinent intrathoracic structures, including systemic veins, pulmonary veins, aorta, lungs, and diaphragm, was assessed. Two patients underwent actual TAH-t placement, with 1 of those patients not meeting standard fit criteria. Both patients had successful virtual implantation, and post-device chest imaging showed no compression of pertinent intrathoracic structures, as predicted by the pre-device simulation.
Research Correspondence Table 1
1181
SynCardia Total Artificial Hearta Virtual Implantation Compatibility Compared with Standard Fit Criteria
Pt
Age (years)
Height (cm)
Weight (kg)
BSA (m2)
T10–sternum distance (cm)
Meets standard fit criteria
3D virtual implant successful
TAH-t device placed
1 2 3 4 5
19 34 20 12 29
160 163 168 141 154
62.3 93.5 62.9 44.6 56.4
1.64 1.98 1.71 1.31 1.54
8.9 10.2 12.1 11.1 9.5
No Yes Yes No No
Yes Yes No No Yes
Yes Yes No No No
3D, 3-dimensional; BSA, body surface area; TAH-t, CardioWest temporary Total Artificial Heart.a a SynCardia Systems, Tucson, Arizona.
Case reports The first patient was a 19-year-old woman with a history of renal cell carcinoma who developed anthracyclineinduced cardiomyopathy and required heart transplantation. Multiple episodes of rejection after transplant led to restrictive cardiomyopathy. She required a biventricular MCS device as a bridge to heart retransplantation; however, she did not meet the TAH-t standard fit criteria. Her BSA was 1.64 m2, and the T10–sternum distance was 8.9 cm. Virtual TAH-t implantation was performed, and the device compatibility within the constraints of the chest wall was assessed (Figure 1A; Video 1, available on the jhltonline.org Web site). Proximity measures noted minimal concern for compression of pertinent structures. She underwent successful TAH-t placement and had no compression-related post-operative complications. Postdevice computed tomography (CT) reconstruction confirmed accurate pre-operative virtual implantation (Figure 2). The patient was transitioned to the Freedom Driver (SynCardia Systems), discharged from the hospital, and underwent successful transplantation after 14 months of support.
The second patient was a 34-year-old woman with complex congenital heart disease who required multiple surgical palliations. Over time, biventricular heart failure developed, and she required biventricular mechanical support. She met the standard criteria for TAH-t (BSA, 1.98 m2; T10–sternum distance, 10.2 cm); however, there were concerns of device compatibility given her history of multiple sternotomies and intrathoracic adhesions. Virtual TAH-t implantation showed no concerns for compression of pertinent structures, and she underwent successful TAH-t placement. Post-device CT reconstruction confirmed accurate preoperative virtual implantation. The patient initially did well; however, overwhelming viremia developed, and she died several months after implantation. The third patient was a 20-year-old man with ectodermal dysplasia, severe scoliosis, and complex congenital heart disease that failed surgical palliation. He was undergoing evaluation for long-term bridge-to-transplant device placement. He met the standard fit criteria for TAH-t placement (BSA, 1.71 m2; T10–sternum distance, 12.1 cm); however, virtual implantation was unsuccessful due to severe scoliosis and significant overlap of the right TAH-t device with the
Figure 1 Comparison of virtual implantation of a temporary total artificial heart in (A) Patient 1 and (B) Patient 3. (A) Patient 1 had a successful virtual implantation of a CardioWest temporary Total Artificial Heart (TAH-t; SynCardia Systems Inc, Tucson, AZ), despite not meeting standard fit criteria. The patient ultimately had a successful TAH-t surgical implantation, was able to undergo chest closure immediately post-operatively, and pertinent anatomic structures were not compressed. (B) Virtual TAH-t implantation failed in Patient 3, despite meeting standard fit criteria. This failure was likely secondary to severe scoliosis that significantly altered the anatomy of the chest wall and intrathoracic cavity.
1182
The Journal of Heart and Lung Transplantation, Vol 33, No 11, November 2014
Figure 2 Series of computed tomography 3-dimensional (3D) reconstructions show (A) preoperative 3D reconstruction, (B) virtual implantation of the CardioWest temporary Total Artificial Heart (TAH-t; SynCardia Systems Inc, Tucson, AZ), and (C) post-device 3D reconstruction with actual TAH-t implantation.
anterior chest wall (Figure 1B; Video 2, available on the jhltonline.org Web site). Given the concerns of device mismatch and severe scoliosis, the patient did not undergo TAH-t placement. The fourth patient was a 12-year-old girl with complex congenital heart disease who had undergone multiple failed palliations and was being considered for device placement as a bridge to heart transplantation. She did not meet standard criteria (BSA, 1.31 m2; T10–sternum distance, 11.1 cm), and virtual implantation was unsuccessful, with the right TAH-t overlapping the anterior chest wall. After extensive discussion, the family decided to postpone TAH-t placement, and she died several weeks later while listed as status 1a for heart transplantation. The fifth patient was a 29-year-old woman with restrictive cardiomyopathy listed for heart transplantation but not in need of a MCS device. She was pre-screened for device placement in the event that acute decompensation would occur. Virtual implantation was successful despite not meeting standard criteria (BSA, 1.54 m2; T10–sternum distance, 9.5 cm). The patient did not require TAH-t placement and underwent a successful transplant several months later.
cohort demonstrates the use of novel 3D imaging techniques to improve patient eligibility for TAH-t placement. With increasing use of MCS devices in adolescent and young adult patients, virtual compatibility testing allows for improved eligibility despite failing standard fit criteria. The introduction of new devices, such as the smaller SynCardia 50 cc/50 cc TAH-t, will benefit from similar rigorous virtual implantation techniques to help establish safer compatibility criteria. In addition, applying this method to other ventricular assist devices that have suggested body size limitations, such as the HeartWare Ventricular Assist Device (HeartWare International, Inc, Framingham, MA), may expand its utility as a screening tool. Future prospective studies and multi-site collaborations are required to adequately test virtual implantation and measure the following outcomes: device incompatibility resulting in an open chest post-operatively, device compression of pertinent structures requiring reoperation, death secondary to device failure, and successful bridge to cardiac transplantation.
Disclosure statement Discussion The SynCardia TAH-t is well suited for certain pediatric and young adult heart failure populations requiring biventricular MCS secondary to chronic transplant rejection, complex congenital heart disease, and restrictive cardiomyopathy. However, the use of TAH-t in these patients carries a risk of device incompatibility. A patient whose chest cannot be closed post-operatively is at increased risk for device malfunction, bleeding, infection, and death.4,5 After the TAH-t is placed and the chest is closed, device compression of pertinent intrathoracic structures remains of high concern. Our
The authors acknowledge Todd Pietila, BS, from Materialise Inc (Plymouth, MI), for assistance in the development of this technique, creation of images and videos, and enhancement of quantitative applications. None of the authors has a financial relationship with a commercial entity that has an interest in the subject of the presented manuscript or other conflicts of interest to disclose.
Supplementary materials Detailed Methods, additional Figures, and a Video demonstration of virtual implantation are available in the online version of this article at jhltonline.org.
Research Correspondence
References 1. Almond CS, Thiagarajan RR, Piercey GE, et al. Waiting list mortality among children listed for heart transplantation in the United States. Circulation 2009;119:717-27. 2. Dembitsky WP, Tector AJ, Park S, et al. Left ventricular assist device performance with long-term circulatory support: lessons from the REMATCH trial. Ann Thorac Surg 2004;78:2123-9: [discussion 2129–30].
A novel method of blood pressure measurement in patients with continuous-flow left ventricular assist devices Kei Woldendorp,a Sunil Gupta, BMedSc (Hons),a Jacqueline Lai, BMedSci (Hons),a Kumud Dhital, PhD, FRACS,a and Christopher S. Hayward, MDa,b From the aHeart Failure and Transplant Unit, St. Vincent’s Hospital and the Faculty of Medicine, The University of New South Wales, Sydney; and the bVictor Chang Cardiac Research Institute, Sydney, New South Wales, Australia.
Continuous-flow LVADs (cfLVADs) have largely replaced pulsatile pumps for chronic mechanical circulatory support in view of improved post-operative morbidity and mortality.1 However, one of the major issues associated with the reduced pulsatility of cfLVADs is non-invasive blood pressure (BP) measurement. Doppler ultrasound of the radial artery combined with a manual sphygmomanometry is the accepted non-invasive method for BP monitoring1 but requires training and dexterity for accurate results. Because of its simplicity and widespread availability, we propose using digital pulse oximetry combined with manual sphygmomanometry to estimate BP in cfLVAD patients. Thirty patients implanted with HeartWare HVAD (HeartWare International Inc, Framingham, MA) pumps were studied in the intensive care unit (ICU) and in the outpatient setting (Supplementary Material, Table 1, available on the jhltonline.org Web site). The study was approved by the
1183 3. Emin A, Rogers CA, Parameshwar J, et al. Trends in long-term mechanical circulatory support for advanced heart failure in the UK. Eur J Heart Fail 2013;15:1185-93. 4. Copeland JG, Smith RG, Arabia FA, et al. Total artificial heart bridge to transplantation: a 9-year experience with 62 patients. J Heart Lung Transplant 2004;23:823-31. 5. Leprince P, Bonnet N, Varnous S, et al. Patients with a body surface area less than 1.7 m2 have a good outcome with the CardioWest Total Artificial Heart. J Heart Lung Transplant 2005;24:1501-5.
St. Vincent’s and Mater Health Human Research Ethics Committee. Fourteen patients were studied in the intensive care unit (ICU). Each patient had intra-arterial pressure, pulse oximetry, Doppler ultrasound, and automated oscillo metric recorded in that order. Eight of the ICU patients, as well as 16 further patients, underwent non-invasive reproducibility studies as outpatients (Figure 1). Devices used are reported in the Supplementary Material (available on the jhltonline.org Web site). Three recordings were attempted for each device by 2 individuals. If a manual cuff was necessary for any of the recordings (pulse oximetry and Doppler), the cuff was evenly deflated at a slow rate of between 2 and 4 mm Hg per second. Aortic valve status was obtained from the most recent available echocardiogram. Repeatability studies were performed and analyzed using one-way analysis of variance. The data for discrete variables were divided into 2 groups and analyzed with the MannWhitney test for unpaired data. Prism 6.0a software (GraphPad Software, Inc, La Jolla, CA) was used for all statistical analysis. ICU recordings were taken a median of 21 days after LVAD implant, with 11 patients studied during the initial implant (median, 8 days; range, 1–50 days) and 3 studied during repeat ICU admission (median, 148 days; range 90–182 days) after LVAD implant. The mean arterial pressure (MAP) by each of the recording methods was similar (Figure 2a). The automated oscillometric systolic blood pressure (Auto SBP) was slightly higher than the intra-arterial pressure (p ¼ 0.038); however, there were no other significant differences (p ¼ 0.056; Figure 2b). MAP by the pulse oximetry method correlated well with intra-arterial MAP (R2 ¼ 0.41, p ¼ 0.0016; Figure 3a). The pulse oximetry MAP was slightly higher than the intra-arterial MAP on Bland-Altman
Figure 1 Patient flow diagram. BP, blood pressure; HVAD, HeartWare (HeartWare, Framingham, MA) left ventricular assist device; ICU, intensive care unit.
The Journal of Heart and Lung Transplantation, Vol 33, No 11, November 2014
days post-procedure is similar to that of a recent study that evaluated allosensitization much later after the NorwoodAG procedure and found that 56% were sensitized at median follow-up of 10.1 years.4 More importantly, almost all our sensitized Norwood-AG patients had very high PRA (HLA Class I or II antibody 450%) as compared with none in the Norwood-nonAG and hybrid groups. Mahle et al showed that patients with very high PRA has the highest risk of death after HTx.1 Although mortality was not significantly different between our study groups, this may become apparent in larger studies. The purpose of this study was to evaluate outcomes of alternative strategies in a group of patients with the highest risk of allosensitization and post-transplant mortality. Our results show that avoidance of allograft use at surgical palliation can lead to less allosensitization, less rejection and favorable posttransplant outcomes in infants with HLHS. Therefore, highrisk patients with HLHS, who are likely to require HTx early in life, may benefit from palliation with a hybrid procedure instead of a Norwood procedure as a bridge to transplant. Moreover, because many HLHS patients will eventually require HTx, aortic arch reconstruction with non-allograft material at time of Norwood palliation should be considered for standard risk patients as well.
Disclosure statement The authors have no conflicts of interest to disclose.
Virtual implantation evaluation of the total artificial heart and compatibility: Beyond standard fit criteria Ryan A. Moore, MD, Peace C. Madueme, MD, Angela Lorts, MD, David L.S. Morales, MD, and Michael D. Taylor, MD, PhD From the Cincinnati Children’s Hospital Medical Center, The Heart Institute, Cincinnati, Ohio
In the United States, children with end-stage heart failure listed for heart transplant face the highest waiting list mortality in transplant medicine.1 Mechanical circulatory support (MCS) devices have revolutionized advanced heart failure management by creating a durable bridge to transplant.2 A shift has occurred in the adult MCS population to intracorporeal MCS devices that allow for ambulatory care while awaiting transplantation.3 The future of pediatric MCS is the expansion of long-term ambulatory devices; however, the pediatric and small adult populations do not typically meet conservative intracorporeal device fit criteria, and poor post-operative outcomes related to device mismatch have been reported.4 The CardioWest temporary Total Artificial Heart (TAH-t; SynCardia Systems Inc, Tucson, AZ) is well suited for
C.I. was supported by the University of Washington Medical Student Research Training Program. The authors thank Yuk Law, MD, for critical reading of the manuscript.
Supplementary materials Supplementary materials associated with this article can be found in the online version at www.jhltonline.org.
References 1. Mahle W, Tresler M, Edens E, et al. Allosensitization and outcomes in pediatric heart transplantation. J Heart Lung Transplant 2011;30: 1221-7. 2. Shaddy R, Hunter D, Osborn K, et al. Prospective analysis of HLA immunogenicity of cryopreserved valved allografts used in pediatric heart surgery. Circulation 1996;94:1063-7. 3. Breinholt J, Hawkins J, Lambert L, et al. A prospective analysis of immunogenicity of cryopreserved nonvalved allografts used in pediatric heart surgery. Circulation 2000;102(suppl 3):III-179-82. 4. O’Connor M, Lind C, Tang X, et al. Persistence of anti-human leucocyte antibodies in congenital heart disease late after surgery using allograft and whole blood. J Heart Lung Transplant 2013;21:390-7. 5. Rossano J, Morales D, Zafar F, et al. Impact of antibodies against human leucocyte antigens on long-term outcome in pediatric heart transplant patients: an analysis of the United Network for Organ Sharing database. J Thorac Cardiovasc Surg 2010;140:694-9. 6. Laing B, Ross D, Meyer S, et al. Glutaraldehyde treatment of allograft tissue decreases allosensitization after the Norwood procedure. J Thorac Cardiovasc Surg 2010;139:1402-8.
certain pediatric and young adult heart failure patients with previously limited MCS options. The standard fit criteria includes a body surface area (BSA) of 1.7 m2 and an anteroposterior distance greater than 10 cm from the sternum to the 10th thoracic vertebra (T10).4 On the basis of these criteria, most pediatric and small adult patients are excluded from TAH-t placement. Innovative imaging techniques are necessary to improve eligibility for TAH-t placement in smaller patients; therefore, we developed a novel technique using virtual TAH-t implantation in pediatric and small adult patients to compare with standard fit criteria. Five patients (aged 12–34 years; BSA, 1.31–1.98 m2) identified as potential candidates for TAH-t as a bridge to cardiac transplantation underwent virtual implantation (Table 1). Detailed methods are available on the jhltonline. org Web site. Briefly, an accurately scaled 3-dimensional (3D) surface rendering of the TAH-t was placed within a 3D reconstruction of the chest to assess for proper fit. Device compression of pertinent intrathoracic structures, including systemic veins, pulmonary veins, aorta, lungs, and diaphragm, was assessed. Two patients underwent actual TAH-t placement, with 1 of those patients not meeting standard fit criteria. Both patients had successful virtual implantation, and post-device chest imaging showed no compression of pertinent intrathoracic structures, as predicted by the pre-device simulation.
Research Correspondence Table 1
1181
SynCardia Total Artificial Hearta Virtual Implantation Compatibility Compared with Standard Fit Criteria
Pt
Age (years)
Height (cm)
Weight (kg)
BSA (m2)
T10–sternum distance (cm)
Meets standard fit criteria
3D virtual implant successful
TAH-t device placed
1 2 3 4 5
19 34 20 12 29
160 163 168 141 154
62.3 93.5 62.9 44.6 56.4
1.64 1.98 1.71 1.31 1.54
8.9 10.2 12.1 11.1 9.5
No Yes Yes No No
Yes Yes No No Yes
Yes Yes No No No
3D, 3-dimensional; BSA, body surface area; TAH-t, CardioWest temporary Total Artificial Heart.a a SynCardia Systems, Tucson, Arizona.
Case reports The first patient was a 19-year-old woman with a history of renal cell carcinoma who developed anthracyclineinduced cardiomyopathy and required heart transplantation. Multiple episodes of rejection after transplant led to restrictive cardiomyopathy. She required a biventricular MCS device as a bridge to heart retransplantation; however, she did not meet the TAH-t standard fit criteria. Her BSA was 1.64 m2, and the T10–sternum distance was 8.9 cm. Virtual TAH-t implantation was performed, and the device compatibility within the constraints of the chest wall was assessed (Figure 1A; Video 1, available on the jhltonline.org Web site). Proximity measures noted minimal concern for compression of pertinent structures. She underwent successful TAH-t placement and had no compression-related post-operative complications. Postdevice computed tomography (CT) reconstruction confirmed accurate pre-operative virtual implantation (Figure 2). The patient was transitioned to the Freedom Driver (SynCardia Systems), discharged from the hospital, and underwent successful transplantation after 14 months of support.
The second patient was a 34-year-old woman with complex congenital heart disease who required multiple surgical palliations. Over time, biventricular heart failure developed, and she required biventricular mechanical support. She met the standard criteria for TAH-t (BSA, 1.98 m2; T10–sternum distance, 10.2 cm); however, there were concerns of device compatibility given her history of multiple sternotomies and intrathoracic adhesions. Virtual TAH-t implantation showed no concerns for compression of pertinent structures, and she underwent successful TAH-t placement. Post-device CT reconstruction confirmed accurate preoperative virtual implantation. The patient initially did well; however, overwhelming viremia developed, and she died several months after implantation. The third patient was a 20-year-old man with ectodermal dysplasia, severe scoliosis, and complex congenital heart disease that failed surgical palliation. He was undergoing evaluation for long-term bridge-to-transplant device placement. He met the standard fit criteria for TAH-t placement (BSA, 1.71 m2; T10–sternum distance, 12.1 cm); however, virtual implantation was unsuccessful due to severe scoliosis and significant overlap of the right TAH-t device with the
Figure 1 Comparison of virtual implantation of a temporary total artificial heart in (A) Patient 1 and (B) Patient 3. (A) Patient 1 had a successful virtual implantation of a CardioWest temporary Total Artificial Heart (TAH-t; SynCardia Systems Inc, Tucson, AZ), despite not meeting standard fit criteria. The patient ultimately had a successful TAH-t surgical implantation, was able to undergo chest closure immediately post-operatively, and pertinent anatomic structures were not compressed. (B) Virtual TAH-t implantation failed in Patient 3, despite meeting standard fit criteria. This failure was likely secondary to severe scoliosis that significantly altered the anatomy of the chest wall and intrathoracic cavity.
1182
The Journal of Heart and Lung Transplantation, Vol 33, No 11, November 2014
Figure 2 Series of computed tomography 3-dimensional (3D) reconstructions show (A) preoperative 3D reconstruction, (B) virtual implantation of the CardioWest temporary Total Artificial Heart (TAH-t; SynCardia Systems Inc, Tucson, AZ), and (C) post-device 3D reconstruction with actual TAH-t implantation.
anterior chest wall (Figure 1B; Video 2, available on the jhltonline.org Web site). Given the concerns of device mismatch and severe scoliosis, the patient did not undergo TAH-t placement. The fourth patient was a 12-year-old girl with complex congenital heart disease who had undergone multiple failed palliations and was being considered for device placement as a bridge to heart transplantation. She did not meet standard criteria (BSA, 1.31 m2; T10–sternum distance, 11.1 cm), and virtual implantation was unsuccessful, with the right TAH-t overlapping the anterior chest wall. After extensive discussion, the family decided to postpone TAH-t placement, and she died several weeks later while listed as status 1a for heart transplantation. The fifth patient was a 29-year-old woman with restrictive cardiomyopathy listed for heart transplantation but not in need of a MCS device. She was pre-screened for device placement in the event that acute decompensation would occur. Virtual implantation was successful despite not meeting standard criteria (BSA, 1.54 m2; T10–sternum distance, 9.5 cm). The patient did not require TAH-t placement and underwent a successful transplant several months later.
cohort demonstrates the use of novel 3D imaging techniques to improve patient eligibility for TAH-t placement. With increasing use of MCS devices in adolescent and young adult patients, virtual compatibility testing allows for improved eligibility despite failing standard fit criteria. The introduction of new devices, such as the smaller SynCardia 50 cc/50 cc TAH-t, will benefit from similar rigorous virtual implantation techniques to help establish safer compatibility criteria. In addition, applying this method to other ventricular assist devices that have suggested body size limitations, such as the HeartWare Ventricular Assist Device (HeartWare International, Inc, Framingham, MA), may expand its utility as a screening tool. Future prospective studies and multi-site collaborations are required to adequately test virtual implantation and measure the following outcomes: device incompatibility resulting in an open chest post-operatively, device compression of pertinent structures requiring reoperation, death secondary to device failure, and successful bridge to cardiac transplantation.
Disclosure statement Discussion The SynCardia TAH-t is well suited for certain pediatric and young adult heart failure populations requiring biventricular MCS secondary to chronic transplant rejection, complex congenital heart disease, and restrictive cardiomyopathy. However, the use of TAH-t in these patients carries a risk of device incompatibility. A patient whose chest cannot be closed post-operatively is at increased risk for device malfunction, bleeding, infection, and death.4,5 After the TAH-t is placed and the chest is closed, device compression of pertinent intrathoracic structures remains of high concern. Our
The authors acknowledge Todd Pietila, BS, from Materialise Inc (Plymouth, MI), for assistance in the development of this technique, creation of images and videos, and enhancement of quantitative applications. None of the authors has a financial relationship with a commercial entity that has an interest in the subject of the presented manuscript or other conflicts of interest to disclose.
Supplementary materials Detailed Methods, additional Figures, and a Video demonstration of virtual implantation are available in the online version of this article at jhltonline.org.
Research Correspondence
References 1. Almond CS, Thiagarajan RR, Piercey GE, et al. Waiting list mortality among children listed for heart transplantation in the United States. Circulation 2009;119:717-27. 2. Dembitsky WP, Tector AJ, Park S, et al. Left ventricular assist device performance with long-term circulatory support: lessons from the REMATCH trial. Ann Thorac Surg 2004;78:2123-9: [discussion 2129–30].
A novel method of blood pressure measurement in patients with continuous-flow left ventricular assist devices Kei Woldendorp,a Sunil Gupta, BMedSc (Hons),a Jacqueline Lai, BMedSci (Hons),a Kumud Dhital, PhD, FRACS,a and Christopher S. Hayward, MDa,b From the aHeart Failure and Transplant Unit, St. Vincent’s Hospital and the Faculty of Medicine, The University of New South Wales, Sydney; and the bVictor Chang Cardiac Research Institute, Sydney, New South Wales, Australia.
Continuous-flow LVADs (cfLVADs) have largely replaced pulsatile pumps for chronic mechanical circulatory support in view of improved post-operative morbidity and mortality.1 However, one of the major issues associated with the reduced pulsatility of cfLVADs is non-invasive blood pressure (BP) measurement. Doppler ultrasound of the radial artery combined with a manual sphygmomanometry is the accepted non-invasive method for BP monitoring1 but requires training and dexterity for accurate results. Because of its simplicity and widespread availability, we propose using digital pulse oximetry combined with manual sphygmomanometry to estimate BP in cfLVAD patients. Thirty patients implanted with HeartWare HVAD (HeartWare International Inc, Framingham, MA) pumps were studied in the intensive care unit (ICU) and in the outpatient setting (Supplementary Material, Table 1, available on the jhltonline.org Web site). The study was approved by the
1183 3. Emin A, Rogers CA, Parameshwar J, et al. Trends in long-term mechanical circulatory support for advanced heart failure in the UK. Eur J Heart Fail 2013;15:1185-93. 4. Copeland JG, Smith RG, Arabia FA, et al. Total artificial heart bridge to transplantation: a 9-year experience with 62 patients. J Heart Lung Transplant 2004;23:823-31. 5. Leprince P, Bonnet N, Varnous S, et al. Patients with a body surface area less than 1.7 m2 have a good outcome with the CardioWest Total Artificial Heart. J Heart Lung Transplant 2005;24:1501-5.
St. Vincent’s and Mater Health Human Research Ethics Committee. Fourteen patients were studied in the intensive care unit (ICU). Each patient had intra-arterial pressure, pulse oximetry, Doppler ultrasound, and automated oscillo metric recorded in that order. Eight of the ICU patients, as well as 16 further patients, underwent non-invasive reproducibility studies as outpatients (Figure 1). Devices used are reported in the Supplementary Material (available on the jhltonline.org Web site). Three recordings were attempted for each device by 2 individuals. If a manual cuff was necessary for any of the recordings (pulse oximetry and Doppler), the cuff was evenly deflated at a slow rate of between 2 and 4 mm Hg per second. Aortic valve status was obtained from the most recent available echocardiogram. Repeatability studies were performed and analyzed using one-way analysis of variance. The data for discrete variables were divided into 2 groups and analyzed with the MannWhitney test for unpaired data. Prism 6.0a software (GraphPad Software, Inc, La Jolla, CA) was used for all statistical analysis. ICU recordings were taken a median of 21 days after LVAD implant, with 11 patients studied during the initial implant (median, 8 days; range, 1–50 days) and 3 studied during repeat ICU admission (median, 148 days; range 90–182 days) after LVAD implant. The mean arterial pressure (MAP) by each of the recording methods was similar (Figure 2a). The automated oscillometric systolic blood pressure (Auto SBP) was slightly higher than the intra-arterial pressure (p ¼ 0.038); however, there were no other significant differences (p ¼ 0.056; Figure 2b). MAP by the pulse oximetry method correlated well with intra-arterial MAP (R2 ¼ 0.41, p ¼ 0.0016; Figure 3a). The pulse oximetry MAP was slightly higher than the intra-arterial MAP on Bland-Altman
Figure 1 Patient flow diagram. BP, blood pressure; HVAD, HeartWare (HeartWare, Framingham, MA) left ventricular assist device; ICU, intensive care unit.
