Modification of a Hybrid Technique for Closure of Muscular Ventricular Septal Defects in a Pig Model
Department of Pediatric Cardiology, University of Munich, Marchioninistrasse 15, Munich, Germany. Heart Surgery Forum
(Impact Factor: 0.39).
10/2010; 13(5):E299-304. DOI: 10.1532/HSF98.20091181
Closure of muscular ventricular septal defects (mVSDs) beyond the moderator band is still a challenge for both surgeons and interventional cardiologists. We evaluated a new technique in a pig model for hybrid patch closure of mVSDs via 2 stab wound incisions in the left ventricle (LV) without cardiopulmonary bypass.
Ten pigs underwent left anterolateral thoracotomy to expose the LV. mVSDs were created via a stab wound incision of the lateral wall of the LV under epicardial echocardiographic control. The patch system was forwarded through a second puncture of the LV apex and positioned in front of the mVSD. The stapler for fixation of the patch was introduced through the same incision as used for VSD creation. Finally, the patch was attached to the septum with nitinol anchors under epicardial echocardiographic and fluoroscopic guidance. Finally, detailed echocardiographic evaluation was done. All hearts were explanted, and macroscopic evaluation was done, either immediately after patch implantation (n = 4) or after 90 days (n = 6).
mVSD creation was successful in all pigs. Closure of mVSDs was successful in 8 of 10 pigs, as confirmed by echocardiography, hemodynamic measurements, and macroscopic examination. One patch embolized through the mVSD into the pulmonary artery because of insecure fixation, and 1 animal died during the procedure because of ventricular fibrillation. The final echocardiographic evaluation revealed good LV function and no damage to the valves.
Closure of mVSDs can be successfully performed in a hybrid technique on the beating heart with 2 stab wound incisions; however, further modifications need to be developed before clinical application.
Available from: Maciej Chojnicki
- "The first successful case of intraoperative perventricular device closure on the beating heart in an infant was reported in 1998 . After that, a few authors have presented their initial experience in hybrid approach with promising results, and techniques are still evolving [8–13]. Following the literature on hybrid therapies, it appears that the advantages of surgical and interventional techniques, which are beneficial in borderline babies who do not meet criteria for surgery or cardiac intervention. "
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The complexity of ventricular septal defects in early infancy led to development of new mini-invasive techniques based on collaboration of cardiac surgeons with interventional cardiologists, called hybrid procedures. Hybrid therapies aim to combine the advantages of surgical and interventional techniques in an effort to reduce the invasiveness. The aim of this study was to present our approach with mVSD patients and initial results in the development of a mini-invasive hybrid procedure in the Gdansk Hybrid Heartlink Programme (GHHP) at the Department of Pediatric Cardiac Surgery, Pomeranian Centre of Traumatology in Gdansk, Poland.
The group of 11 children with mVSDs was enrolled in GHHP and 6 were finally qualified to hybrid trans-ventricular mVSD device closure. Mean age at time of hybrid procedure was 8.22 months (range: from 2.7 to 17.8 months, SD=5.1) and mean body weight was 6.3 kg (range: from 3.4 to 7.5 kg, SD=1.5).
The implants of choice were Amplatzer VSD Occluder and Amplatzer Duct Occluder II (AGA Med. Corp, USA). The position of the implants was checked carefully before releasing the device with both transesophageal echocardiography and epicardial echocardiography. All patients survived and their general condition improved. No complications occurred. The closure of mVSD was complete in all children.
Hybrid procedures of periventricular muscular VSD closure appear feasible and effective for patients with septal defects with morphology unsuitable for classic surgical or interventional procedures. The modern strategy of joint cardiac surgical and interventional techniques provides the benefits of close cooperation between cardiac surgeon and interventional cardiologist for selected patients in difficult clinical settings.
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Current materials for closure of cardiac defects such as ventricular septal defects (VSDs) are associated with compliance mismatch and a chronic inflammatory response. Bacterial nanocellulose (BNC) is a non-degradable biomaterial with promising properties such as high mechanical strength, favourable elasticity and a negligible inflammatory reaction. The aim of this study was the evaluation of a BNC patch for VSD closure and the investigation of its in vivo biocompatibility in a chronic pig model.
Young's modulus and tensile strength of BNC patches were determined before and after blood exposure. Muscular VSDs were created and closed with a BNC patch on the beating heart in an in vivo pig model. Hearts were explanted after 7, 30 or 90 days. Macropathology, histology and immunohistochemistry were performed.
Young's modulus and tensile strength of the BNC patch decreased after blood contact from 6.3 ± 1.9 to 3.86 ± 2.2 MPa (P < 0.01) and 0.33 ± 0.06 to 0.26 ± 0.06 MPa (P < 0.01), respectively, indicating the development of higher elasticity. Muscular VSDs were closed with a BNC patch without residual shunting. After 90 days, a mild chronic inflammatory reaction was present. Moreover, there was reduced tissue overgrowth in comparison with polyester. Proceeding cellular organization characterized by fibromuscular cells, production of extracellular matrix, neoangiogenesis and complete neoendothelialization were found. There were no signs of thrombogenicity.
BNC patches can close VSDs with good mid-term results and its biocompatibility can be considered as satisfactory. Its elasticity increases in the presence of blood, which might be advantageous. Therefore, it has potential to be used as an alternative patch material in congenital heart disease.
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