Angiographic tool to detect pulmonary arteriovenous malformations in single ventricle physiology.

OBJECTIVE: Individuals with single ventricle physiology who are palliated with superior cavopulmonary anastomosis (Glenn surgery) may develop pulmonary arteriovenous malformations. The traditional tools for pulmonary arteriovenous malformation diagnosis are often of limited diagnostic utility in this patient population. We sought to measure the pulmonary capillary transit time to determine its value as a tool to identify pulmonary arteriovenous malformations in patients with single ventricle physiology. METHODS: We defined the angiographic pulmonary capillary transit time as the number of cardiac cycles required for transit of contrast from the distal pulmonary arteries to the pulmonary veins. Patients were retrospectively recruited from a single quaternary North American paediatric centre, and angiographic and clinical data were reviewed. Pulmonary capillary transit time was calculated in 20 control patients and compared to 20 single ventricle patients at the pre-Glenn, Glenn, and Fontan surgical stages (which were compared with a linear-mixed model). Correlation (Pearson) between pulmonary capillary transit time and haemodynamic and injection parameters was assessed using angiograms from 84 Glenn patients. Five independent observers calculated pulmonary capillary transit time to measure reproducibility (intraclass correlation coefficient). RESULTS: Mean pulmonary capillary transit time was 3.3 cardiac cycles in the control population, and 3.5, 2.4, and 3.5 in the pre-Glenn, Glenn, and Fontan stages, respectively. Pulmonary capillary transit time in the Glenn population did not correlate with injection conditions. Intraclass correlation coefficient was 0.87. CONCLUSIONS: Pulmonary angiography can be used to calculate the pulmonary capillary transit time, which is reproducible between observers. Pulmonary capillary transit time accelerates in the Glenn stage, correlating with absence of direct hepatopulmonary venous flow.

Angiographic Tool to Detect Pulmonary Arteriovenous Malformations in Single Ventricle Physiology.

Background: Individuals with single ventricle physiology who are palliated with superior cavopulmonary anastomosis (Glenn surgery) may develop pulmonary arteriovenous malformations (PAVMs). The traditional tools for PAVM diagnosis are often of limited diagnostic utility in this patient population. We sought to measure the pulmonary capillary transit time (PCTT) to determine its value as a tool to identify PAVMs in patients with single ventricle physiology. Methods: We defined the angiographic PCTT as the number of cardiac cycles required for transit of contrast from the distal pulmonary arteries to the pulmonary veins. Patients were retrospectively recruited from a single quaternary North American pediatric center, and angiographic and clinical data was reviewed. PCTT was calculated in 20 control patients and compared to 20 single ventricle patients at the pre-Glenn, Glenn, and Fontan surgical stages (which were compared with a linear-mixed model). Correlation (Pearson) between PCTT and hemodynamic and injection parameters was assessed using 84 Glenn angiograms. Five independent observers calculated PCTT to measure reproducibility (intra-class correlation coefficient). Results: Mean PCTT was 3.3 cardiac cycles in the control population, and 3.5, 2.4, and 3.5 in the pre-Glenn, Glenn, and Fontan stages, respectively. PCTT in the Glenn population did not correlate with injection conditions. Intraclass correlation coefficient was 0.87. Conclusions: Pulmonary angiography can be used to calculate the pulmonary capillary transit time, which is reproducible between observers. PCTT accelerates in the Glenn stage, correlating with absence of direct hepatopulmonary venous flow.

Improved catheter tracking during cardiovascular magnetic resonance-guided cardiac catheterization using overlay visualization.

INTRODUCTION: Cardiovascular magnetic resonance (CMR)-guided cardiac catheterization is becoming more widespread due to the ability to acquire both functional CMR measurements and diagnostic catheterization data without exposing patients to ionizing radiation. However, the real-time imaging sequences used for catheter guidance during these procedures are limited in resolution and the anatomical detail they can provide. In this study, we propose a passive catheter tracking approach which simultaneously improves catheter tracking and visualization of the anatomy. METHODS: 60 patients with congenital heart disease underwent CMR-guided cardiac catheterization on a 1.5T CMR scanner (Ingenia, Philips Healthcare, Best the Netherlands) using the Philips iSuite system. The proposed T1-overlay technique uses a commercially available heavily T1-weighted sequence to image the catheter, and overlays it on a high-resolution 3D dataset within iSuite in real-time. Suppressed tissue in the real-time images enables the use of a thick imaging slab to assist in tracking of the catheter. Improvement in catheter visualization time was compared between T1-overlay and the conventional invasive CMR (iCMR) balanced steady state free precession (bSSFP) sequence. This technique also enabled selective angiography visualization for real-time evaluation of blood flow dynamics (such as pulmonary transit time), similar to direct contrast injection under standard fluoroscopy. Estimates of pulmonary transit time using iCMR were validated using x-ray fluoroscopy in 16 patients. RESULTS: The T1-overlay approach significantly increased the time that the catheter tip was kept in view by the technologist compared to the bSSFP sequence conventionally used for iCMR. The resulting images received higher ratings for blood/balloon contrast, anatomy visualization, and overall suitability for iCMR guidance by three cardiologists. iCMR selective angiography using T1-overlay also provided accurate estimates of pulmonary transit time that agreed well with x-ray fluoroscopy. CONCLUSION: We demonstrate a new passive catheter tracking technique using the iSuite platform that improves visualization of the catheter and cardiac anatomy. These improvements significantly increase the time that the catheter tip is seen throughout the procedure. We also demonstrate the feasibility of iCMR selective angiography for the measurement of pulmonary transit time.

Transcatheter Device Therapy and the Integration of Advanced Imaging in Congenital Heart Disease.

Transcatheter device intervention is now offered as first line therapy for many congenital heart defects (CHD) which were traditionally treated with cardiac surgery. While off-label use of devices is common and appropriate, a growing number of devices are now specifically designed and approved for use in CHD. Advanced imaging is now an integral part of interventional procedures including pre-procedure planning, intra-procedural guidance, and post-procedure monitoring. There is robust societal and industrial support for research and development of CHD-specific devices, and the regulatory framework at the national and international level is patient friendly. It is against this backdrop that we review transcatheter implantable devices for CHD, the role and integration of advanced imaging, and explore the current regulatory framework for device approval.

Fick versus flow: a real-time invasive cardiovascular magnetic resonance (iCMR) reproducibility study.

BACKGROUND: Cardiac catheterization and cardiovascular magnetic resonance (CMR) imaging have distinct diagnostic roles in the congenital heart disease (CHD) population. Invasive CMR (iCMR) allows for a more thorough assessment of cardiac hemodynamics at the same time under the same conditions. It is assumed but not proven that iCMR gives an incremental value by providing more accurate flow quantification. METHODS: Subjects with CHD underwent real-time 1.5 T iCMR using a passive catheter tracking technique with partial saturation pulse of 40° to visualize the gadolinium-filled balloon, CMR-conditional guidewire, and cardiac structures simultaneously to aid in completion of right (RHC) and left heart catheterization (LHC). Repeat iCMR and catheterization measurements were performed to compare reliability by the Pearson (PCC) and concordance correlation coefficients (CCC). RESULTS: Thirty CHD (20 single ventricle and 10 bi-ventricular) subjects with a median age and weight of 8.3 years (2-33) and 27.7 kg (9.2-80), respectively,  successfully underwent iCMR RHC and LHC. No catheter related complications were encountered. Time taken for first pass RHC and LHC/aortic pull back was 5.1, and 2.9 min, respectively. Total success rate to obtain required data points to complete Fick principle calculations for all patients was 321/328 (98%). One patient with multiple shunts was an outlier and excluded from further analysis. The PCC for catheter-derived pulmonary blood flow (Qp) (0.89, p < 0.001) is slightly lower than iCMR-derived Qp (0.96, p < 0.001), whereas catheter-derived systemic blood flow (Qs) (0.62, p = < 0.001) was considerably lower than iCMR-derived Qs (0.94, p < 0.001). CCC agreement for Qp at baseline (C1-CCC = 0.65, 95% CI 0.41-0.81) and retested conditions (C2-CCC = 0.78, 95% CI 0.58-0.89) were better than for Qs at baseline (C1-CCC = 0.22, 95% CI - 0.15-0.53) and retested conditions (C2-CCC = 0.52, 95% CI 0.17-0.76). CONCLUSION: This study further validates hemodynamic measurements obtained via iCMR. iCMR-derived flows have considerably higher test-retest reliability for Qs. iCMR evaluations allow for more reproducible hemodynamic assessments in the CHD population.

Lymphatic pathway evaluation in congenital heart disease using 3D whole-heart balanced steady state free precession and T2-weighted cardiovascular magnetic resonance.

BACKGROUND: Due to passive blood flow in palliated single ventricle, central venous pressure increases chronically, ultimately impeding lymphatic drainage. Early visualization and treatment of these malformations is essential to reduce morbidity and mortality. Cardiovascular magnetic resonance (CMR) T2-weighted lymphangiography (T2w) is used for lymphatic assessment, but its low signal-to-noise ratio may result in incomplete visualization of thoracic duct pathway. 3D-balanced steady state free precession (3D-bSSFP) is commonly used to assess congenital cardiac disease anatomy. Here, we aimed to improve diagnostic imaging of thoracic duct pathway using 3D-bSSFP. METHODS: Patients underwent CMR during single ventricle or central lymphatic system assessment using T2w and 3D-bSSFP. T2w parameters included 3D-turbo spin echo (TSE), TE/TR = 600/2500 ms, resolution = 1 × 1 × 1.8 mm, respiratory triggering with bellows. 3D-bSSFP parameters included electrocardiogram triggering and diaphragm navigator, 1.6 mm isotropic resolution, TE/TR = 1.8/3.6 ms. Thoracic duct was identified independently in T2w and 3D-bSSFP images, tracked completely from cisterna chyli to its drainage site, and classified based on severity of lymphatic abnormalities. RESULTS: Forty-eight patients underwent CMR, 46 of whom were included in the study. Forty-five had congenital heart disease with single ventricle physiology. Median age at CMR was 4.3 year (range 0.9-35.1 year, IQR 2.4 year), and median weight was 14.4 kg (range, 7.9-112.9 kg, IQR 5.2 kg). Single ventricle with right dominant ventricle was noted in 31 patients. Thirty-eight patients (84%) were status post bidirectional Glenn and 7 (16%) were status post Fontan anastomosis. Thoracic duct visualization was achieved in 45 patients by T2w and 3D-bSSFP. Complete tracking to drainage site was attained in 11 patients (24%) by T2w vs 25 (54%) by 3D-bSSFP and in 28 (61%) by both. Classification of lymphatics was performed in 31 patients. CONCLUSION: Thoracic duct pathway can be visualized by 3D-bSSFP combined with T2w lymphangiography. Cardiac triggering and respiratory navigation likely help retain lymphatic signal in the retrocardiac area by 3D-bSSFP. Visualizing lymphatic system leaks is challenging on 3D-bSSFP images alone, but 3D-bSSFP offers good visualization of duct anatomy and landmark structures to help plan interventions. Together, these sequences can define abnormal lymphatic pathway following single ventricle palliative surgery, thus guiding lymphatic interventional procedures.

Use of institutional criteria for transcatheter device closure of Fontan fenestration - Midterm outcomes.

BACKGROUND: There are no established criteria to decide suitability for Fontan fenestration closure. Our institution has the following criteria: an unobstructed Fontan pathway with no significant decompressing venovenous collaterals, baseline Fontan pressure ≤15 mmHg, baseline cardiac index ≥2 L/min/m2, and a decrease in cardiac index ≤20% with test occlusion of the fenestration. OBJECTIVE: The objective of the study was to review midterm outcomes following device closure of Fontan fenestration using institutional criteria. MATERIALS AND METHODS: A retrospective review was performed of patients who underwent catheterization with prior fenestrated Fontan procedure between May 2005 and January 2015. Patients were classified as those who underwent successful closure (A), had closure deferred due to failure to meet criteria (B), or were not referred for closure (C). RESULTS: There were 42 patients in Group A, 10 in Group B, and 150 in Group C. The mean Fontan pressure increased from 13.1 ± 2.1 to 14.5 ± 2.1mmHg in Group A and 14.6 ± 1.5 to 15.7 ± 2.2 mmHg in Group B (P = not significant). With test occlusion, cardiac index fell by 18.12% ± 15.68% in Group A and 33.75% ± 14.98% in Group B (P = 0.019). At a median of 46 month follow-up, oxygen saturation increased significantly from 85.15% ± 6.29% at baseline to 94.6% ± 4.43% (P < 0.001) in Group A but with no statistically significant difference in the rates of plastic bronchitis, protein-losing enteropathy, stroke, or heart transplantation between the three groups. CONCLUSIONS: Using institutional criteria, transcatheter device closure of Fontan fenestration was followed by significant increase in oxygen saturations and no statistically significant difference in morbidity or mortality between closure and nonclosure groups.

ACCAPA: anomalous circumflex coronary artery origin from pulmonary artery.

Anomalous circumflex coronary artery origin from pulmonary artery is a very rare congenital heart disease. Misdiagnosis of this condition may lead to inadequate myocardial protection during cardiopulmonary bypass surgery.

Invasive cardiovascular magnetic resonance (iCMR) for diagnostic right and left heart catheterization using an MR-conditional guidewire and passive visualization in congenital heart disease.

BACKGROUND: Today's standard of care, in the congenital heart disease (CHD) population, involves performing cardiac catheterization under x-ray fluoroscopy and cardiac magnetic resonance (CMR) imaging separately. The unique ability of CMR to provide real-time functional imaging in multiple views without ionizing radiation exposure has the potential to be a powerful tool for diagnostic and interventional procedures. Limiting fluoroscopic radiation exposure remains a challenge for pediatric interventional cardiologists. This pilot study's objective is to establish feasibility of right (RHC) and left heart catheterization (LHC) during invasive CMR (iCMR) procedures at our institution in the CHD population. Furthermore, we aim to improve simultaneous visualization of the catheter balloon tip, MR-conditional guidewire, and cardiac/vessel anatomy during iCMR procedures. METHODS: Subjects with CHD were enrolled in a pilot study for iCMR procedures at 1.5 T with an MR-conditional guidewire. The CMR area is located adjacent to a standard catheterization laboratory. Using the interactive scanning mode for real-time control of the imaging location, a dilute gadolinium-filled balloon-tip catheter was used in combination with an MR-conditional guidewire to obtain cardiac saturations and hemodynamics. A recently developed catheter tracking technique using a real-time single-shot balanced steady-state free precession (bSSFP), flip angle (FA) 35-45°, echo time (TE) 1.3 ms, repetition time (TR) 2.7 ms, 40° partial saturation (pSAT) pre-pulse was used to visualize the gadolinium-filled balloon, MR-conditional guidewire, and cardiac structures simultaneously. MR-conditional guidewire visualization was enabled due to susceptibility artifact created by distal markers. Pre-clinical phantom testing was performed to determine the optimum imaging FA-pSAT combination. RESULTS: The iCMR procedure was successfully performed to completion in 31/34 (91%) subjects between August 1st, 2017 to December 13th, 2018. Median age and weight were 7.7 years and 25.2 kg (range: 3 months - 33 years and 8 - 80 kg). Twenty-one subjects had single ventricle (SV) anatomy: one subject was referred for pre-Glenn evaluation, 11 were pre-Fontan evaluations and 9 post-Fontan evaluations for protein losing enteropathy (PLE) and/or cyanosis. Thirteen subjects had bi-ventricular (BiV) anatomy, 4 were referred for coarctation of the aorta (CoA) evaluations, 3 underwent vaso-reactivity testing with inhaled nitric oxide, 3 investigated RV volume dimensions, two underwent branch PA stenosis evaluation, and the remaining subject was status post heart transplant. No catheter related complications were encountered. Average time taken for first pass RHC, LHC/aortic pull back, and to cross the Fontan fenestration was 5.2, 3.0, and 6.5 min, respectively. Total success rate to obtain required data points to complete Fick principle calculations for all patients was 331/337 (98%). Subjects were transferred to the x-ray fluoroscopy lab if further intervention was required including Fontan fenestration device closure, balloon angioplasty of pulmonary arteries/conduits, CoA stenting, and/or coiling of aortopulmonary (AP) collaterals. Starting with subject #10, an MR-conditional guidewire was used in all subsequent subjects (15 SV and 10 BiV) with a success rate of 96% (24/25). Real-time CMR-guided RHC (25/25 subjects, 100%), retrograde and prograde LHC/aortic pull back (24/25 subjects, 96%), CoA crossing (3/4 subjects, 75%) and Fontan fenestration test occlusion (2/3 subjects, 67%) were successfully performed in the majority of subjects when an MR-conditional guidewire was utilized. CONCLUSION: Feasibility for detailed diagnostic RHC, LHC, and Fontan fenestration test occlusion iCMR procedures in SV and BiV pediatric subjects with complex CHD is demonstrated with the aid of an MR-conditional guidewire. A novel real-time pSAT GRE sequence with optimized FA-pSAT angle has facilitated simultaneous visualization of the catheter balloon tip, MR-conditional guidewire, and cardiac/vessel anatomy during iCMR procedures.

Relationship Between Time to Left Atrial Decompression and Outcomes in Patients Receiving Venoarterial Extracorporeal Membrane Oxygenation Support: A Multicenter Pediatric Interventional Cardiology Early-Career Society Study.

OBJECTIVES: To assess the variation in timing of left atrial decompression and its association with clinical outcomes in pediatric patients supported with venoarterial extracorporeal membrane oxygenation across a multicenter cohort. DESIGN: Multicenter retrospective study. SETTING: Eleven pediatric hospitals within the United States. PATIENTS: Patients less than 18 years on venoarterial extracorporeal membrane oxygenation who underwent left atrial decompression from 2004 to 2016. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A total of 137 patients (median age, 4.7 yr) were included. Cardiomyopathy was the most common diagnosis (47%). Cardiac arrest (39%) and low cardiac output (50%) were the most common extracorporeal membrane oxygenation indications. Median time to left atrial decompression was 6.2 hours (interquartile range, 3.8-17.2 hr) with the optimal cut-point of greater than or equal to 18 hours for late decompression determined by receiver operating characteristic curve. In univariate analysis, late decompression was associated with longer extracorporeal membrane oxygenation duration (median 8.5 vs 5 d; p = 0.02). In multivariable analysis taking into account clinical confounder and center effects, late decompression remained significantly associated with prolonged extracorporeal membrane oxygenation duration (adjusted odds ratio, 4.4; p = 0.002). Late decompression was also associated with longer duration of mechanical ventilation (adjusted odds ratio, 4.8; p = 0.002). Timing of decompression was not associated with in-hospital survival (p = 0.36) or overall survival (p = 0.42) with median follow-up of 3.2 years. CONCLUSIONS: In this multicenter study of pediatric patients receiving venoarterial extracorporeal membrane oxygenation, late left atrial decompression (≥ 18 hr) was associated with longer duration of extracorporeal membrane oxygenation support and mechanical ventilation. Although no survival benefit was demonstrated, the known morbidities associated with prolonged extracorporeal membrane oxygenation use may justify a recommendation for early left atrial decompression.

Biodegradable Stents for Congenital Heart Disease.

The quest for an ideal biodegradable stent for both adult coronary and pediatric congenital heart disease applications continues. Over the past few years, a lot of progress has been made toward development of a dedicated pediatric biodegradable stent that can be used for congenital heart disease applications. At present, there are no biodegradable stents available for use in congenital heart disease. In this article, the authors review the different biodegradable materials and their limitations and provide an overview of the current biodegradable stents being evaluated for congenital heart disease applications.

Invasive Hemodynamics of Adult Congenital Heart Disease: From Shunts to Coarctation.

Adults with congenital heart disease are a growing population with increasingly more complex disease, in large part due to improvements in delivery of care to the pediatric population. Cardiac catheterization is an integral component of diagnosis and management in these patients. Careful attention to detail and a thorough understanding of intracardiac hemodynamics are critical to performing complete diagnostic evaluations. This article outlines the most commonly encountered lesions with guidelines for invasive assessment to help guide further therapy.

New-onset cardiac rhabdomyoma beyond infancy in a patient with tuberous sclerosis complex.

Cardiac rhabdomyomas in patients with tuberous sclerosis complex are usually detected antenatally or during infancy, with subsequent stabilisation or spontaneous regression. Development of a new cardiac rhabdomyoma beyond infancy is very rare. We report a male child who needed resection of a large rhabdomyoma in neonatal life, and then developed a new-onset rhabdomyoma at 2 years of age in a different location, needing another resection. Routine surveillance for cardiac rhabdomyomas in asymptomatic patients with tuberous sclerosis is essential.

A novel design biodegradable stent for use in congenital heart disease: mid-term results in rabbit descending aorta.

OBJECTIVES: This study evaluates the feasibility of delivery and deployment of low and medium molecular weight (LMW and MMW, respectively) double-opposing helical (DH) poly-l-lactic acid biodegradable stent (BDS) in rabbit descending aorta (DAO). Secondary objectives were to assess patency and inflammation of stented vessels at 9 months and to investigate safety following intentional embolization of stent fragments in DAO. BACKGROUND: A BDS that will relieve aortic obstruction and disappears as the child grows older allowing for preservation of aortic wall elasticity and natural growth of aorta will be ideal to treat Coarctation (CoA). BDS have never been evaluated in the DAO. METHODS: Seven New Zealand white rabbits underwent implantation of DH-LMW (n = 7), DH-MMW (n = 3), and metal stents (n = 7) in DAO. BDS fragments were intentionally embolized into DAO in two rabbits. RESULTS: All stents were deployed via a 6-French sheath. Five BDS covered the origin of major DAO side branches. Angiography and intravascular ultrasound showed good stent apposition to the wall of DAO with minimal luminal loss at 9 months follow-up. All stents had minimal neointimal hyperplasia on histopathology. Adverse events included 1 death, 1 aortic aneurysm, and lower extremity ulceration due to self-mutilation in an embolization rabbit. CONCLUSIONS: Pilot study confirms the feasibility of delivery and deployment of up to 6-millimeter diameter DH BDS in rabbit DAO. Stent integrity with DH design was maintained at 9 months with minimal vessel inflammation. Potential morbidity due to embolized BD fragments cannot be ruled out and needs further evaluation.

Hypoplastic left heart syndrome secondary to intrauterine rhabdomyoma necessitating single ventricle palliation.

Rhabdomyoma, a benign hamartomatous tumor of the cardiac embryonic myocyte, is the most common intrauterine cardiac tumor and accounts for 0.12% of prenatal fetal studies. Fetal cardiac rhabdomyomas increase in size during second and early third trimester and spontaneously regress postnatally. The clinical presentation is usually benign, however, compromise of the ventricular outflow tract leading to decreased cardiac output and fetal death have been reported. We present a case of large cardiac rhabdomyoma in a fetus that might have caused complete left ventricular outflow tract obstruction and development of hypoplastic left heart syndrome (HLHS) necessitating postnatal single ventricle palliation therapy. The clinical course and outcomes of prenatally diagnosed cardiac rhabdomyoma are reviewed and theories of the development of hypoplastic left heart syndrome are explored.

Amplatzer vascular plug IV for occlusion of pulmonary arteriovenous malformations in a patient with cryptogenic stroke.

Paradoxical embolism resulting in cryptogenic stroke has received much attention recently, with the primary focus on patent foramen ovale (PFO). However, it is essential to be vigilant in the search for other causes of paradoxical embolic events, such as pulmonary arteriovenous malformations (PAVM). We describe successful closure of pulmonary AVM with a St Jude Medical (Plymouth, MN) Amplatzer™ vascular plug IV. The newer AVP-IV devices can be used for successful embolization of tortuous pulmonary AVM in remote locations where use of other traditional devices may be technically challenging.

A novel biodegradable stent applicable for use in congenital heart disease: bench testing and feasibility results in a rabbit model.

OBJECTIVES: A novel double opposed helical (DH) biodegradable stent was designed and fabricated for CHD applications. The primary objective was to evaluate the feasibility of DH stent delivery and deployment in rabbit external iliac arteries (EIA). Secondary objectives were to assess stent patency, thrombosis and inflammation at 1-week and 1-month follow-up. BACKGROUND: Biodegradable stents have largely been designed for adult cardiovascular indications, to avoid long term complications of permanent implants. A growing child with congenital heart disease (CHD) would especially derive substantial benefit from this technology. METHODS: DH stents were manufactured to 3, 4, 5, and 6-mm diameter with poly-l-lactic acid (PLLA) fibers. Bench test analysis was performed. Six DH stents were implanted in rabbit EIA. Vessel patency was assessed at 1-week and 1-month follow-up with repeat angiography, intravascular ultrasound (IVUS). Histopathological evaluation was performed. RESULTS: The elastic recoil and collapse pressure of DH stents were comparable to conventional metal stents. All DH stents were successfully delivered and implanted with good apposition to the vessel wall and no collapse of the proximal, mid or distal ends. All stented vessels remained patent. No acute or early stent thrombosis was noted. Histopathology showed minimal inflammatory response and mild neointimal proliferation at 1 month follow-up. CONCLUSIONS: In vitro results of DH PLLA biodegradable stents are comparable to conventional metal stents. The pilot animal study confirms the delivery and deployment of the DH stents to the desired location. The DH design can be used to fabricate larger diameter stents needed for CHD.