Minimally Invasive Cardiac Surgery: Transapical Aortic Valve Replacement

Cardiothoracic Surgery Research Program, National Heart, Lung, and Blood Institute, National Institutes of Health, 9000 Rockville Pike, Bldg 10, B1D47, Bethesda, MD 20892, USA.
Minimally Invasive Surgery 10/2012; 2012(6):145381. DOI: 10.1155/2012/145381
Source: PubMed


Minimally invasive cardiac surgery is less traumatic and therefore leads to quicker recovery. With the assistance of engineering technologies on devices, imaging, and robotics, in conjunction with surgical technique, minimally invasive cardiac surgery will improve clinical outcomes and expand the cohort of patients that can be treated. We used transapical aortic valve implantation as an example to demonstrate that minimally invasive cardiac surgery can be implemented with the integration of surgical techniques and engineering technologies. Feasibility studies and long-term evaluation results prove that transapical aortic valve implantation under MRI guidance is feasible and practical. We are investigating an MRI compatible robotic surgical system to further assist the surgeon to precisely deliver aortic valve prostheses via a transapical approach. Ex vivo experimentation results indicate that a robotic system can also be employed in in vivo models.

Download full-text


Available from: Ming Li
  • Source
    • "However, neither of these systems have demonstrated applicability for TAVI-related procedures. Li et al. described a robotic system capable of TA-TAVI under magnetic resonance imaging (MRI) [13], [14]. But MR-imaging does not allow visualization of the existing catheters used in TAVI-related procedures without the use of markers. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Recent technological advancements in cardiovas-cular surgery such as transapical transcatheter aortic valve implantation (TA-TAVI) enabled treatment to elderly that were initially declined surgery. However, valve malpositioning during TA-TAVI have been reported in several cases. In this preliminary study, we present a novel approach in which a Robotically-Actuated Delivery Sheath (RADS) is used to potentially facilitate valve positioning. A model is developed that describes the shape and articulating tip position of the RADS. We developed a two-dimensional ultrasound tracking method that evaluates the tip position of the RADS in ultrasound images. Both modeling and ultrasound tracking are combined into an integrated system that facilitates closed-loop control of the articulating tip of the RADS. Experiments are performed in order to evaluate the tracking accuracy of the RADS. Experiments show mean positioning errors of approximately 2 mm along the x-and y-axes. Our study demonstrates that the RADS can potentially provide compensation for beating heart and respiratory motions during valve positioning and deployment in TA-TAVI.
    Full-text · Conference Paper · Jun 2014
  • [Show abstract] [Hide abstract]
    ABSTRACT: Ifrg15 is a newly identified interferon alpha responsive gene and is implicated in a wide variety of physiological roles in mammals. In the present study, multiple alignments of the deduced amino acids of 10 eutherian mammalian IFRG15/Ifrg15s isolated from open genomic database revealed that they were highly conserved. Real-time PCR showed that mouse Ifrg15 mRNA was expressed in MII stage oocytes and preimplantation embryos, and its highest value peaked at the stage of mouse blastocysts. To understand the effect of three development-related genes on the promoter activity of mouse Ifrg15, promoter analysis using luciferase assays in COS-7 cells were performed. The results showed that the transcription of mouse Ifrg15 was suppressed by Oct4 and Nanog when transfected with the longest Ifrg15 promoter reporter gene. After the relatively shorter promoters were co-transfected with Oct4, c-Myc and Nanog, the relative luciferase activities of Ifrg15 were gradually increased. These in vitro results data and expression profiles of Ifrg15 as revealed by real-time PCR partly indicated that Ifrg15 transcription might be either potentially regulated or dependent on the post-transcriptional effects of IFN-α mediated by the three genes indirectly. Our data suggested that the mouse Ifrg15 might interact with these key development-related genes and play significant roles on the mouse preimplantation embryos development, especially for the development of mouse blastocysts.
    No preview · Article · Jul 2012 · Gene
  • [Show abstract] [Hide abstract]
    ABSTRACT: Oestrogens and Insulin-like growth factors (Igfs) play both a central role in the regulation of reproduction and growth and can interact especially in species showing a clear-cut sex-linked growth dimorphism (SGD) like in tilapia. Aromatase is essential in ovarian differentiation and oogenesis since it controls oestrogen synthesis. During tilapia sex differentiation, aromatase cyp19a1a expression increases from 9 days post-fertilization (dpf), resulting in high oestradiol level. High temperature, exogenous androgens or aromatase inhibitors override genetic sex differentiation inducing testes development through the suppression of cyp19a1a gene expression and aromatase activity. Supplementation with 17ß-oestradiol (E2) of gonadectomized juveniles induced a sustained and higher E2 plasma level than in intact or gonadectomized controls and both sexes showed reduced growth. Juvenile and mature females treated with the aromatase inhibitor 1,4,6-androstatriene-3,17-dione had 19% lower E2 plasma level compared to controls and they showed a 32% increased growth after 28 days of treatment. Altogether, these data suggest that E2 inhibits female growth leading to the SGD. Regarding Igf-1, mRNA and peptide appeared in liver at ∼4 dpf and then in organs involved in growth and metabolism, indicating a role in early growth, metabolism and organogenesis. Gonad igf-1 showed an early expression and the peptide could be detected at ∼7 dpf in somatic cells. It appeared in germ cells at the onset of ovarian (29 dpf) and testicular (52 dpf) meiosis. In testis, Igf-1 together with steroids may regulate spermatogenesis whereas in ovary it participates in steroidogenesis regulation. Igf-1 and Igf-2 promote proliferation of follicular cells and oocyte maturation. Igf-3 expression is gonad specific and localized in the ovarian granulosa or testicular interstitial cells. In developing gonads igf-3 is up-regulated in males but down-regulated in females. In contrast, bream Gh injections increased igf-1 mRNA in male and female liver and ovaries but gonadal igf-3 was not affected. Thus, local Igf-1 and Igf-2 may play crucial roles in the formation, development and function of gonads while Igf-3 depending on the species is involved in male and female reproduction. Furthermore, precocious ethynyloestradiol (EE) exposure induced lasting effects on growth, through pituitary gh inhibition, local suppression of igf-1 expression and in testis only down-regulation of igf-3 mRNA. In conclusion, SGD in tilapia may be driven through an inhibitory effect due to E2 synthesis in female and involving Igfs regulation.
    No preview · Article · Jul 2014 · General and Comparative Endocrinology
Show more