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Intra-operative fitting study of the PediPump ventricular assist device
Comments and Opinions
109
Probability of no infection 0.50 0.25 0.75
1.00
References 1. Gordon R, Quagliarello B, Lowy F. Ventricular assist device-related infections. Lancet Infect Dis 2006;6:426-37. 2. Zierer A, Melby SJ, Voeller RK, et al. Late-onset driveline infections: the Achilles’ heel of prolonged left ventricular assist device support. Ann Thorac Surg 2007;84:515-20. 3. Raymond AL, Kfoury AG, Bishop CJ, et al. Obesity and left ventricular assist device driveline exit site infection. ASAIO J 2010;56:57-60.
0.00
Foam Gauze
0
200 400 Time from implant (days)
600
Figure 1 Kaplan-Meier curve shows time to infection for the foam group (solid line) and gauze group (dashed line) during 540 days of follow-up. Log-rank p ⫽ 0.58; Wilcoxon p ⫽ 0.54.
in the two groups. Driveline infections were defined according to the International Society for Heart and Lung Transplantation Consensus statement. Groups were compared using chi-square, Fisher’s exact, Mann-Whitney, or t-tests, as appropriate. Kaplan-Meier curves were compared using the log-rank and Wilcoxon tests. Analyses were performed with SAS 9.2 (SAS Institute, Cary, NC) and Stata 11 software (StataCorp, College Station, TX) We identified 16 patients who used the Utah foam-based technique and 47 who used the gauze technique. Patients were monitored for the duration of VAD support, but follow-up was truncated at 18 months for the purpose of this analysis because no patients with the Utah technique had more than 18 months of follow-up. Data for 3 caregivers in the foam group and 1 caregiver and 1 patient in the gauze group were not available. Baseline characteristics, infection, and satisfaction are reported in Table 1. Caregiver satisfaction was significantly higher in the Utah technique group (Table 1). As shown in Figure 1, we noted non-inferiority of the foam dressing technique to the gauze dressing in 18 months of follow-up in the 2 groups with comparable body mass index and duration of support, 2 factors that have previously been shown to increase the risk of driveline infection.2,3 We observed good outcomes with both techniques, a finding that may empower clinical teams to offer the technique most suitable for an individual patient rather than relying exclusively on a single method within a program.
Intra-operative fitting study of the PediPump ventricular assist device Diyar Saeed, MD,a Kiyotaka Fukamachi, MD, PhD,a and Brian W. Duncan, MD, MBAb a Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio and b Department of Pediatric and Congenital Heart Surgery, Children’s Hospital, Cleveland Clinic, Cleveland, Ohio
To the Editor: Issues related to anatomic fit of implantable ventricular assist devices (VADs) are particularly important during the development of devices intended for implantation in pediatric patients or in patients with a small body surface area (BSA) of ⬍1.5 m2.1 Anatomic fit assessment using animal models or human cadavers is limited by cost, time and test subject availability. We are developing the PediPump, a miniature VAD, designed specifically for pediatric applications.2 The PediPump, 10 mm in diameter and 70 mm in length, offers the potential of being implantable in small children. To assess fitting of the PediPump VAD, we aimed to evaluate intraoperative device fitting and determine optimal placement strategies in pediatric patients at the time of routine cardiac surgical procedures. Our study was approved by the institutional review board of the Cleveland Clinic. Device fitting was performed using a sterile silicone pump model in patients undergoing elective cardiac surgical procedures (Figure 1). Intra-operative measurements included the diameter of the major vessels and their shortest distances to the sternum and diaphragm and the clearances between the left and right ventricular surfaces and the sternum and the left ventricular apex to the ascending aorta dimension. Device fit was evaluated for
Disclosure statement Dr Eckman has received research support and honoraria from Thoratec and honoraria from HeartWare. None of the other 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. No funding source was needed for this study.
Figure 1
PediPump silicon model and outflow graft.
110
The Journal of Heart and Lung Transplantation, Vol 31, No 1, January 2012 Society, Mannheim, Germany, 2010. We thank Fumoto Hideyuki, MD, Stephan Weber, Dipl-Ing, Tomohiro Anzai, MD, PhD, Nicole Mielke, BS, and William A. Smith, DEng, PE, for their contributions to this study.
References
Figure 2 Intra-operative fitting study in a 3-year old patient. Better device fitting was observed with the pump placed on the diaphragm.
both left and right VAD applications, and cannula length and angle were determined for each application. Fitting was determined for pump placement in two configurations: (1) on the diaphragmatic surface of the heart; and (2) along the lateral ventricular wall. Intra-operative fitting studies were performed in 6 pediatric patients with a BSA range of 0.23 to 0.63 m2. Better fitting of the current pump prototype, for use as a left or right VAD, was possible when the model was placed on the diaphragm anterior to the ventricles. Intracorporeal implantation of the current pump prototype in the 3-month-old infants was hindered by the lack of retrosternal space for placement of the outflow graft with likely coronary and lung compression. Full intracorporeal implantation in Patient 4 (11 months of age, BSA 0.63 m2) also seemed to create the potential for lung compression. Intracorporeal implantation appeared to be feasible in both 3-year-old patients (Figure 2). We have previously described the usefulness of 3-dimensional on-screen models in providing device-fitting information that could help overcome some limitations associated with animal and cadaver studies.3 In the present study, intra-operative fitting provided additional in vivo information that augments data derived from other sources. Unlike imaging or cadaver studies, this in vivo approach allows direct visualization of possible positional interferences due to device placement during normal cardiac motion with full lung inflation. It also provides information regarding the lower limits of patient size for which an implantable system could be considered; for the present prototype, intracorporeal implantation in toddlers appears to be feasible. Based on these results, a next generation version of the PediPump that is considerably smaller is currently being developed and will undergo similar in vivo fitting studies to determine whether it can be adapted for use in infants.
Disclosure statement The authors have no conflicts of interest to disclose. This study was presented at the 76th annual meeting of the German Cardiac
1. Griffith BP. Children are not necessarily “small” adults: the growing field of miniaturized mechanical circulatory support. J Heart Lung Transplant 2011;30:9-11. 2. Duncan BW, Dudzinski DT, Gu L, et al. The PediPump: development status of a new pediatric ventricular assist device: update II. ASAIO J 2006;52:581-7. 3. Saeed D, Ootaki Y, Noecker A, et al. The Cleveland Clinic PediPump: virtual fitting studies in children using three-dimensional reconstructions of cardiac computed tomography scans. ASAIO J 2008;54:133-7.
Successful bridge to transplantation for pediatric lupus cardiomyopathy Christina J. VanderPluym, MD,a Ivan Rebeyka, MD,b and Holger Buchholz, MDb From the aDepartment of Pediatrics, Division of Cardiology and the bDivision of Cardiovascular Surgery, University of Alberta, Stollery Children’s Hospital, Edmonton, Alberta, Canada.
Increased rejection risk due to heightened immune reactivity in patients with active systemic lupus erythematous (SLE) previously precluded consideration of solid organ transplantation. However, favorable experience with renal transplantation in this population has advanced the field to a few heart and heart-lung transplantations as well.1,2 We report our experience with left ventricular assist device (LVAD) support with the EXCOR (Berlin Heart GmbH, Berlin, Germany) in an adolescent patient with SLE as a bridge-to-decision and, ultimately, to transplantation. A 16-year-old boy with a new diagnosis of SLE was listed for heart transplantation 1 year after the SLE diagnosis with progressive heart failure (New York Heart Association class IV) due to severe ventricular dysfunction. The onset of progressive multiorgan failure refractory to maximal medical therapy prompted implantation of an 80-ml EXCOR LVAD. Pending end-organ recovery and immunologic quiescence of SLE, heart transplant listing was placed on hold. His postoperative course was uncomplicated. He was discharged home with a portable driver on Day 249, sustained a cannula site infection on Day 332, and underwent pump change for clot in the LVAD outflow on Day 477. SLE treatment consisted of monthly intravenous cyclophosphamide. He was relisted for transplantation on Day 611 after complete end-organ recovery and no evidence of active SLE. He received an allograft on Day 678. The endomyocardial biopsy specimens at 1, 2, and 3 months revealed International Society for Heart and Lung Transplantation (ISHLT) 1R rejection.3 Subsequent monthly biopsy specimens revealed no rejection. Despite strict adherence to his immunosuppressant regimen, im-
109
Probability of no infection 0.50 0.25 0.75
1.00
References 1. Gordon R, Quagliarello B, Lowy F. Ventricular assist device-related infections. Lancet Infect Dis 2006;6:426-37. 2. Zierer A, Melby SJ, Voeller RK, et al. Late-onset driveline infections: the Achilles’ heel of prolonged left ventricular assist device support. Ann Thorac Surg 2007;84:515-20. 3. Raymond AL, Kfoury AG, Bishop CJ, et al. Obesity and left ventricular assist device driveline exit site infection. ASAIO J 2010;56:57-60.
0.00
Foam Gauze
0
200 400 Time from implant (days)
600
Figure 1 Kaplan-Meier curve shows time to infection for the foam group (solid line) and gauze group (dashed line) during 540 days of follow-up. Log-rank p ⫽ 0.58; Wilcoxon p ⫽ 0.54.
in the two groups. Driveline infections were defined according to the International Society for Heart and Lung Transplantation Consensus statement. Groups were compared using chi-square, Fisher’s exact, Mann-Whitney, or t-tests, as appropriate. Kaplan-Meier curves were compared using the log-rank and Wilcoxon tests. Analyses were performed with SAS 9.2 (SAS Institute, Cary, NC) and Stata 11 software (StataCorp, College Station, TX) We identified 16 patients who used the Utah foam-based technique and 47 who used the gauze technique. Patients were monitored for the duration of VAD support, but follow-up was truncated at 18 months for the purpose of this analysis because no patients with the Utah technique had more than 18 months of follow-up. Data for 3 caregivers in the foam group and 1 caregiver and 1 patient in the gauze group were not available. Baseline characteristics, infection, and satisfaction are reported in Table 1. Caregiver satisfaction was significantly higher in the Utah technique group (Table 1). As shown in Figure 1, we noted non-inferiority of the foam dressing technique to the gauze dressing in 18 months of follow-up in the 2 groups with comparable body mass index and duration of support, 2 factors that have previously been shown to increase the risk of driveline infection.2,3 We observed good outcomes with both techniques, a finding that may empower clinical teams to offer the technique most suitable for an individual patient rather than relying exclusively on a single method within a program.
Intra-operative fitting study of the PediPump ventricular assist device Diyar Saeed, MD,a Kiyotaka Fukamachi, MD, PhD,a and Brian W. Duncan, MD, MBAb a Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio and b Department of Pediatric and Congenital Heart Surgery, Children’s Hospital, Cleveland Clinic, Cleveland, Ohio
To the Editor: Issues related to anatomic fit of implantable ventricular assist devices (VADs) are particularly important during the development of devices intended for implantation in pediatric patients or in patients with a small body surface area (BSA) of ⬍1.5 m2.1 Anatomic fit assessment using animal models or human cadavers is limited by cost, time and test subject availability. We are developing the PediPump, a miniature VAD, designed specifically for pediatric applications.2 The PediPump, 10 mm in diameter and 70 mm in length, offers the potential of being implantable in small children. To assess fitting of the PediPump VAD, we aimed to evaluate intraoperative device fitting and determine optimal placement strategies in pediatric patients at the time of routine cardiac surgical procedures. Our study was approved by the institutional review board of the Cleveland Clinic. Device fitting was performed using a sterile silicone pump model in patients undergoing elective cardiac surgical procedures (Figure 1). Intra-operative measurements included the diameter of the major vessels and their shortest distances to the sternum and diaphragm and the clearances between the left and right ventricular surfaces and the sternum and the left ventricular apex to the ascending aorta dimension. Device fit was evaluated for
Disclosure statement Dr Eckman has received research support and honoraria from Thoratec and honoraria from HeartWare. None of the other 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. No funding source was needed for this study.
Figure 1
PediPump silicon model and outflow graft.
110
The Journal of Heart and Lung Transplantation, Vol 31, No 1, January 2012 Society, Mannheim, Germany, 2010. We thank Fumoto Hideyuki, MD, Stephan Weber, Dipl-Ing, Tomohiro Anzai, MD, PhD, Nicole Mielke, BS, and William A. Smith, DEng, PE, for their contributions to this study.
References
Figure 2 Intra-operative fitting study in a 3-year old patient. Better device fitting was observed with the pump placed on the diaphragm.
both left and right VAD applications, and cannula length and angle were determined for each application. Fitting was determined for pump placement in two configurations: (1) on the diaphragmatic surface of the heart; and (2) along the lateral ventricular wall. Intra-operative fitting studies were performed in 6 pediatric patients with a BSA range of 0.23 to 0.63 m2. Better fitting of the current pump prototype, for use as a left or right VAD, was possible when the model was placed on the diaphragm anterior to the ventricles. Intracorporeal implantation of the current pump prototype in the 3-month-old infants was hindered by the lack of retrosternal space for placement of the outflow graft with likely coronary and lung compression. Full intracorporeal implantation in Patient 4 (11 months of age, BSA 0.63 m2) also seemed to create the potential for lung compression. Intracorporeal implantation appeared to be feasible in both 3-year-old patients (Figure 2). We have previously described the usefulness of 3-dimensional on-screen models in providing device-fitting information that could help overcome some limitations associated with animal and cadaver studies.3 In the present study, intra-operative fitting provided additional in vivo information that augments data derived from other sources. Unlike imaging or cadaver studies, this in vivo approach allows direct visualization of possible positional interferences due to device placement during normal cardiac motion with full lung inflation. It also provides information regarding the lower limits of patient size for which an implantable system could be considered; for the present prototype, intracorporeal implantation in toddlers appears to be feasible. Based on these results, a next generation version of the PediPump that is considerably smaller is currently being developed and will undergo similar in vivo fitting studies to determine whether it can be adapted for use in infants.
Disclosure statement The authors have no conflicts of interest to disclose. This study was presented at the 76th annual meeting of the German Cardiac
1. Griffith BP. Children are not necessarily “small” adults: the growing field of miniaturized mechanical circulatory support. J Heart Lung Transplant 2011;30:9-11. 2. Duncan BW, Dudzinski DT, Gu L, et al. The PediPump: development status of a new pediatric ventricular assist device: update II. ASAIO J 2006;52:581-7. 3. Saeed D, Ootaki Y, Noecker A, et al. The Cleveland Clinic PediPump: virtual fitting studies in children using three-dimensional reconstructions of cardiac computed tomography scans. ASAIO J 2008;54:133-7.
Successful bridge to transplantation for pediatric lupus cardiomyopathy Christina J. VanderPluym, MD,a Ivan Rebeyka, MD,b and Holger Buchholz, MDb From the aDepartment of Pediatrics, Division of Cardiology and the bDivision of Cardiovascular Surgery, University of Alberta, Stollery Children’s Hospital, Edmonton, Alberta, Canada.
Increased rejection risk due to heightened immune reactivity in patients with active systemic lupus erythematous (SLE) previously precluded consideration of solid organ transplantation. However, favorable experience with renal transplantation in this population has advanced the field to a few heart and heart-lung transplantations as well.1,2 We report our experience with left ventricular assist device (LVAD) support with the EXCOR (Berlin Heart GmbH, Berlin, Germany) in an adolescent patient with SLE as a bridge-to-decision and, ultimately, to transplantation. A 16-year-old boy with a new diagnosis of SLE was listed for heart transplantation 1 year after the SLE diagnosis with progressive heart failure (New York Heart Association class IV) due to severe ventricular dysfunction. The onset of progressive multiorgan failure refractory to maximal medical therapy prompted implantation of an 80-ml EXCOR LVAD. Pending end-organ recovery and immunologic quiescence of SLE, heart transplant listing was placed on hold. His postoperative course was uncomplicated. He was discharged home with a portable driver on Day 249, sustained a cannula site infection on Day 332, and underwent pump change for clot in the LVAD outflow on Day 477. SLE treatment consisted of monthly intravenous cyclophosphamide. He was relisted for transplantation on Day 611 after complete end-organ recovery and no evidence of active SLE. He received an allograft on Day 678. The endomyocardial biopsy specimens at 1, 2, and 3 months revealed International Society for Heart and Lung Transplantation (ISHLT) 1R rejection.3 Subsequent monthly biopsy specimens revealed no rejection. Despite strict adherence to his immunosuppressant regimen, im-