Browsing by Author "Rodefeld, Mark D."
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Item Autonomous Fontan pump: Computational feasibility study(Elsevier, 2024-07-15) Rodefeld, Mark D.; Conover, Timothy; Figliola, Richard; Neary, Mike; Giridharan, Guruprasad; Ivashchenko, Artem; Bennett, Edward M.; Surgery, School of MedicineObjective: After Fontan palliation, patients with single-ventricle physiology are committed to chronic circulatory inefficiency for the duration of their lives. This is due in large part to the lack of a subpulmonary ventricle. A low-pressure rise cavopulmonary assist device can address the subpulmonary deficit and offset the Fontan paradox. We investigated the feasibility of a Fontan pump that is self-powered by tapping reserve pressure energy in the systemic arterial circulation. Methods: A double-inlet, double-outlet rotary pump was designed to augment Fontan flow through the total cavopulmonary connection. Pump power is supplied by a systemic arterial shunt and radial turbine, with a closed-loop shunt return to the common atrium (QP:QS 1:1). Computational fluid dynamic analysis and lumped parameter modeling of pump impact on the Fontan circulation was performed. Results: Findings indicate that a pump that can augment all 4 limbs of total cavopulmonary connection flow (superior vena cava/inferior vena cava inflow; left pulmonary artery/right pulmonary artery outflow) using a systemic arterial shunt powered turbine at a predicted cavopulmonary pressure rise of +2.5 mm Hg. Systemic shunt flow is 1.43 lumped parameter model, 22% cardiac output. Systemic venous pressure is reduced by 1.4 mm Hg with improved ventricular preload and cardiac output. Conclusions: It may be possible to tap reserve pressure energy in the systemic circulation to improve Fontan circulatory efficiency. Further studies are warranted to optimize, fabricate, and test pump designs for hydraulic performance and hemocompatibility. Potential benefits of an autonomous Fontan pump include durable physiologic shift toward biventricular health, freedom from external power, autoregulating function and exercise responsiveness, and improved quality and duration of life.Item Cavopulmonary assist for the failing Fontan circulation: impact of ventricular function on mechanical support strategy(Ovid Technologies (Wolters Kluwer) - Lippincott Williams & Wilkins, 2014-11) Giridharan, Guruprasad A.; Ising, Mickey; Sobieski, Michael A.; Koenig, Steven C.; Chen, Jun; Frankel, Steven C.; Rodefeld, Mark D.; Department of Surgery, IU School of MedicineMechanical circulatory support--either ventricular assist device (VAD, left-sided systemic support) or cavopulmonary assist device (CPAD, right-sided support)--has been suggested as treatment for Fontan failure. The selection of left- versus right-sided support for failing Fontan has not been previously defined. Computer simulation and mock circulation models of pediatric Fontan patients (15-25 kg) with diastolic, systolic, and combined systolic and diastolic dysfunction were developed. The global circulatory response to assisted Fontan flow using VAD (HeartWare HVAD, Miami Lakes, FL) support, CPAD (Viscous Impeller Pump, Indianapolis, IN) support, and combined VAD and CPAD support was evaluated. Cavopulmonary assist improves failing Fontan circulation during diastolic dysfunction but preserved systolic function. In the presence of systolic dysfunction and elevated ventricular end-diastolic pressure (VEDP), VAD support augments cardiac output and diminishes VEDP, while increased preload with cavopulmonary assist may worsen circulatory status. Fontan circulation can be stabilized to biventricular values with modest cavopulmonary assist during diastolic dysfunction. Systemic VAD support may be preferable to maintain systemic output during systolic dysfunction. Both systemic and cavopulmonary support may provide best outcome during combined systolic and diastolic dysfunction. These findings may be useful to guide clinical cavopulmonary assist strategies in failing Fontan circulations.Item Cavopulmonary assist: Long-term reversal of the Fontan paradox(Elsevier, 2019-12) Rodefeld, Mark D.; Marsden, Alison; Figliola, Richard; Jonas, Travis; Neary, Michael; Giridharan, Guruprasad A.; Surgery, School of MedicineObjective Fontan circulatory inefficiency can be addressed by replacing the missing subpulmonary power source to reverse the Fontan paradox. An implantable cavopulmonary assist device is described that will simultaneously reduce systemic venous pressure and increase pulmonary arterial pressure, improving preload and cardiac output, in a univentricular Fontan circulation on a long-term basis. Methods A rotary blood pump that was based on the von Karman viscous pump was designed for implantation into the total cavopulmonary connection (TCPC). It will impart modest pressure energy to augment Fontan flow without risk of obstruction. In the event of rotational failure, it is designed to default to a passive flow diverter. Pressure-flow performance was characterized in vitro in a Fontan mock circulatory loop with blood analog. Results The pump performed through the fully specified operating range, augmenting flow in all 4 directions of the TCPC. Pressure rise of 6 to 8 mm Hg was readily achieved, ranging to 14 mm Hg at highest speed (5600 rpm). Performance was consistent across a wide range of cardiac outputs. In stalled condition (0 rpm), there was no discernible pressure loss across the TCPC. Conclusions A blood pump technology is described that can reverse the Fontan paradox and may permit a surgical strategy of long-term biventricular maintenance of a univentricular Fontan circulation. The technology is intended for Fontan failure in which right-sided circulatory inefficiencies predominate and ventricular systolic function is preserved. It may also apply before clinical Fontan failure as health maintenance to preempt the progression of Fontan disease.Item Multiblock High Order Large Eddy Simulation of Powered Fontan Hemodynamics: Towards Computational Surgery(Elsevier, 2017-01-17) Delorme, Yann T.; Rodefeld, Mark D.; Frankel, Steven H.; Surgery, School of MedicineChildren born with only one functional ventricle must typically undergo a series of three surgeries to obtain the so-called Fontan circulation in which the blood coming from the body passively flows from the Vena Cavae (VCs) to the Pulmonary Arteries (PAs) through the Total Cavopulmonary Connection (TCPC). The circulation is inherently inefficient due to the lack of a subpulmonary ventricle. Survivors face the risk of circulatory sequelae and eventual failure for the duration of their lives. Current efforts are focused on improving the outcomes of Fontan palliation, either passively by optimizing the TCPC, or actively by using mechanical support. We are working on a chronic implant that would be placed at the junction of the TCPC, and would provide the necessary pressure augmentation to re-establish a circulation that recapitulates a normal two-ventricle circulation. This implant is based on the Von Karman viscous pump and consists of a vaned impeller that rotates inside the TCPC. To evaluate the performance of such a device, and to study the flow features induced by the presence of the pump, Computational Fluid Dynamics (CFD) is used. CFD has become an important tool to understand hemodynamics owing to the possibility of simulating quickly a large number of designs and flow conditions without any harm for patients. The transitional and unsteady nature of the flow can make accurate simulations challenging. We developed and in-house high order Large Eddy Simulation (LES) solver coupled to a recent Immersed Boundary Method (IBM) to handle complex geometries. Multiblock capability is added to the solver to allow for efficient simulations of complex patient specific geometries. Blood simulations are performed in a complex patient specific TCPC geometry. In this study, simulations without mechanical assist are performed, as well as after virtual implantation of the temporary and chronic implants being developed. Instantaneous flow structures, hepatic factor distribution, and statistical data are presented for all three cases.Item Outcomes in patients with interrupted aortic arch and associated anomalies: a 20-year experience(Elsevier, 2006-05-01) Brown, John W.; Ruzmetov, Mark; Okada, Yuji; Vijay, Palaniswamy; Rodefeld, Mark D.; Turrentine, Mark W.; Surgery, School of MedicineObjective: The surgical results for the repair of interrupted aortic arch (IAA) have evolved in recent years. We report our results for staged repair of this complex congenital malformation. Methods: Sixty-five patients (mean age, 16.9 ± 41.7 days) were diagnosed with IAA and referred for surgical therapy. The surgical management strategy at our institution between 1982 and 2005 has been one-stage complete repair (n = 13) or staged repair (n = 52) in selected patients. Non-complex patients (group I, n = 51) had a ventricular septal defect (87%), aortopulmonary window (8%), and left ventricular outflow tract obstruction (27%). Group II (n = 14) were patients with Taussig–Bing double outlet right ventricle (n = 6) or truncus arteriosus (n = 8). Method of staged repair of IAA was to transect and turn down the left carotid artery and anastomosis it to the descending aorta (n = 41) or graft interposition (n = 2) combined with a pulmonary artery (PA) banding followed in a few months by delayed ventricular septal defect (VSD) closure and PA de-banding. Results: There were 5 early and 10 late deaths. The actuarial survival including early mortality was 92% at 1 year, 81% at 5 years, and 76% at 10 and 15 years. There was an 81% 15-year survival for children in group I compared with a 54% for children in group II (p ≪ 0.001). Risk factors for increased mortality by univariate analysis were as follows: (1) primary aortic anastomosis (p = 0.03), (2) presence of complex anomalies (p = 0.05), and (3) initial IAA repair performed before 1994 (p = 0.05). Actuarial freedom from any type of aortic reoperation or intervention was 86% at 1 year, 69% at 5 years, and 60% at 10 and 15 years. Univariate and multivariate analyses identified no tested variables as risk factors for reoperation. The majority (86%) was in New York Heart Association (NYHA) class I, and 14% remained in NYHA class II. During the postoperative course there were no neurologic deficits, seizures, and growth disturbances in any patient. Conclusion: Staged repair of IAA using a left carotid artery turn down can be safely applied in IAA patients with and without other intracardiac anomalies with good results. Use of the left carotid artery for arch reconstruction did not result in any detectable neurological events or growth disturbances later in life. Associated anomalies played an important role in outcomes. The long-term probability for reoperation and/or reintervention remains high regardless of operative technique.Item Passive performance evaluation and validation of a viscous impeller pump for subpulmonary fontan circulatory support(Springer Nature, 2023-08-04) Yang, Weiguang; Conover, Timothy A.; Figliola, Richard S.; Giridharan, Guruprasad A.; Marsden, Alison L.; Rodefeld, Mark D.; Surgery, School of MedicinePatients with single ventricle defects undergoing the Fontan procedure eventually face Fontan failure. Long-term cavopulmonary assist devices using rotary pump technologies are currently being developed as a subpulmonary power source to prevent and treat Fontan failure. Low hydraulic resistance is a critical safety requirement in the event of pump failure (0 RPM) as a modest 2 mmHg cavopulmonary pressure drop can compromise patient hemodynamics. The goal of this study is therefore to assess the passive performance of a viscous impeller pump (VIP) we are developing for Fontan patients, and validate flow simulations against in-vitro data. Two different blade heights (1.09 mm vs 1.62 mm) and a blank housing model were tested using a mock circulatory loop (MCL) with cardiac output ranging from 3 to 11 L/min. Three-dimensional flow simulations were performed and compared against MCL data. In-silico and MCL results demonstrated a pressure drop of < 2 mmHg at a cardiac output of 7 L/min for both blade heights. There was good agreement between simulation and MCL results for pressure loss (mean difference − 0.23 mmHg 95% CI [0.24–0.71]). Compared to the blank housing model, low wall shear stress area and oscillatory shear index on the pump surface were low, and mean washout times were within 2 s. This study demonstrated the low resistance characteristic of current VIP designs in the failed condition that results in clinically acceptable minimal pressure loss without increased washout time as compared to a blank housing model under normal cardiac output in Fontan patients.Item Right Ventricular Outflow Tract Reconstruction in Infant Truncus Arteriosus: A 37-year Experience(Elsevier, 2020-01) Herrmann, Jeremy L.; Larson, Emilee E.; Mastropietro, Christopher W.; Rodefeld, Mark D.; Turrentine, Mark W.; Nozaki, Ryoko; Brown, John W.; Surgery, School of MedicineBackground Multiple conduits for right ventricular outflow tract reconstruction exist, although the ideal conduit that maximizes outcomes remains controversial. We evaluated long-term outcomes and compared conduits for right ventricular outflow tract reconstruction in children with truncus arteriosus. Methods Records of patients who underwent truncus arteriosus repair at our institution between 1981 and 2018 were retrospectively reviewed. Primary outcomes included survival and freedom from catheter reintervention or reoperation. Secondary analyses evaluated the effect of comorbidity, operation era, conduit type, and conduit size. Results One hundred patients met inclusion criteria. Median follow-up time was 15.6 years (interquartile range, 5.3-22.2). Actuarial survival at 30 days, 5 years, 10 years, and 15 years was 85%, 72%, 72%, and 68%, respectively. Early mortality was associated with concomitant interrupted aortic arch (hazard ratio, 5.4; 95% confidence interval, 1.7-17.4; P = .005). Median time to surgical reoperation was 4.6 years (interquartile range, 2.9-6.8; n = 58). Right ventricle to pulmonary artery continuity was established with an aortic homograft (n = 14), pulmonary homograft (n = 41), or bovine jugular vein conduit (n = 36) in most cases. Multivariate analysis revealed longer freedom from reoperation with the bovine jugular vein conduit compared with the aortic homograft (hazard ratio, 3.1; 95% confidence interval, 1.3-7.7; P = .02) with no difference compared with the pulmonary homograft. Larger conduit size was associated with longer freedom from reoperation (hazard ratio, 0.7; 95% confidence interval, 0.6-0.9; P < .001). Conclusions The bovine jugular vein conduit is a favorable conduit for right ventricular outflow tract reconstruction in patients with truncus arteriosus. Concomitant interrupted aortic arch is a risk factor for early mortality.Item Tracheostomy Following Surgery for Congenital Heart Disease: 14-year Institutional Experience(Sage, 2016-05) Benneyworth, Brian D.; Shao, Jenny M.; Cristea, A. Ioana; Ackerman, Veda; Rodefeld, Mark D.; Turrentine, Mark W.; Brown, John W.; Department of Pediatrics, IU School of MedicineBackground: Tracheostomy following congenital heart disease (CHD) surgery is a rare event and associated with significant mortality. Hospital survival has been reported from 20% to 40%. Late mortality for these patients is not well characterized. Methods: We performed a retrospective observational study of patients who had a tracheostomy following CHD surgery (excluding isolated patent ductus arteriosus ligation) between January 2000 and December 2013. Patients were categorized into single-ventricle or biventricular physiology groups. Demographics, genetic syndromes, pulmonary disease, and comorbidities were collected. Outcomes including hospital survival, long-term survival, and weaning from positive pressure ventilation are reported. Bivariate and time-to-event models were used. Results: Over a 14-year period, 61 children (0.9% incidence) had a tracheostomy placed following CHD surgery. There were 12 single-ventricle patients and 49 biventricular patients. Prematurity, genetic syndromes, lung/airway disease, and other comorbidities were common in both CHD groups. Gastrostomy tubes were used more frequently in biventricular physiology patients (91.8%) versus single-ventricle patients (66.7%, P = .04). Survival to hospital discharge was 50% in the single-ventricle group compared to 86% in biventricular patients (P = .01). Long-term survival continued to be poor in the single-ventricle group comparatively (three years, 27.8% vs 64.8%, P = .01). Gastrostomy tube placement was independently associated with survival in both groups (P = .002). Conclusion: Tracheostomy is performed following many types of surgery for CHD and is commonly associated with other comorbidities. Both hospital and long-term survival are substantially lower in children with single-ventricle physiology as compared to patients with biventricular physiology.Item Vasoactive-ventilation-renal score reliably predicts hospital length of stay after surgery for congenital heart disease(Elsevier, 2016-11) Scherer, Bradley; Moser, Elizabeth A. S.; Brown, John W.; Rodefeld, Mark D.; Turrentine, Mark W.; Mastropietro, Christopher W.; Department of Pediatrics, IU School of MedicineObjectives We aimed to further validate the vasoactive-ventilation-renal score as a predictor of outcome in patients recovering from surgery for congenital heart disease. We also sought to determine the optimal time point within the early recovery period at which the vasoactive-ventilation-renal score should be measured. Methods We prospectively reviewed consecutive patients recovering from cardiac surgery within our intensive care unit between January 2015 and June 2015. The vasoactive-ventilation-renal score was calculated at 6, 12, 24, and 48 hours postoperatively as follows: vasoactive-ventilation-renal score = ventilation index + vasoactive-inotrope score + Δ creatinine [change in serum creatinine from baseline*10]. Primary outcome of interest was prolonged hospital length of stay, defined as length of stay in the upper 25%. Receiver operating characteristic curves were generated, and areas under the curve with 95% confidence intervals were calculated for all time points. Multivariable logistic regression modeling also was performed. Results We reviewed 164 patients with a median age of 9.25 months (interquartile range, 2.6-58 months). Median length of stay was 8 days (interquartile range, 5-17.5 days). The area under the curve value for the vasoactive-ventilation-renal score as a predictor of prolonged length of stay (>17.5 days) was greatest at 12 hours postoperatively (area under the curve = 0.93; 95% confidence interval, 0.89-0.97). On multivariable regression analysis, after adjustment for potential confounders, the 12-hour vasoactive-ventilation-renal score remained a strong predictor of prolonged hospital length of stay (odds ratio, 1.15; 95% confidence interval, 1.10-1.20). Conclusions In a heterogeneous population of patients undergoing surgery for congenital heart disease, the novel vasoactive-ventilation-renal score calculated in the early postoperative recovery period can be a strong predictor of prolonged hospital length of stay.