Triggered activity due to delayed afterdepolarizations in sites of focal origin of ischemic ventricular tachycardia

2004 ◽  
Vol 287 (5) ◽  
pp. H2078-H2084 ◽  
Author(s):  
Dezhi Xing ◽  
James B. Martins
Keyword(s):  
Ventricular Tachycardia ◽  
Three Dimensional ◽  
In Vitro Study ◽  
Coronary Artery Ligation ◽  
Artery Ligation ◽  
Triggered Activity ◽  
Anesthetized Dogs ◽  
Delayed Afterdepolarizations ◽  
First Time

This study for the first time systematically evaluated the site of origin of focal ventricular tachycardia (VT) induced 1–3 h after acute coronary artery ligation in dogs. We determined whether delayed afterdepolarizations (DADs) and triggered activity (TA) are more often recorded from ischemic endocardium excised from focal sites of VT origin. A total of 145 α-chloralose-anesthetized dogs were studied: in 54 dogs without inducible VT, normal or ischemic endocardium was investigated in vitro; in 91 dogs, inducible VT was studied by three-dimensional activation mapping, with in vitro study of 51 endocardial foci compared with 40 endocardial ischemic sites not of VT origin. Incidence of DADs (71% vs. 33%, P < 0.05) and TA (32% vs. 11%, P < 0.05) was greater in ischemic than in normal Purkinje tissues. Purkinje sites of origin of focal VT demonstrated the greatest frequency of DADs (92%, P < 0.05) and TA (75%, P < 0.05), with repetitive TA predominating. Similar results were obtained in endocardial sites of origin. Action potentials were mildly depolarized and prolonged in the focal sites of origin. These abnormalities were stable up to 2.5 h of recording. This study demonstrated that DADs and TA may underlie a majority of focal VTs in ischemic endocardium and Purkinje tissue.

Pharmacological stimulation of cardiac gap junction coupling does not affect ischemia-induced focal ventricular tachycardia or triggered activity in dogs

2005 ◽  
Vol 288 (2) ◽  
pp. H511-H516 ◽  
Author(s):  
Dezhi Xing ◽  
Anne Louise Kjølbye ◽  
Jørgen S. Petersen ◽  
James B. Martins
Keyword(s):  
Ventricular Tachycardia ◽  
Gap Junction ◽  
Plasma Concentrations ◽  
Three Dimensional ◽  
In Vitro Study ◽  
Coronary Artery Occlusion ◽  
Artery Occlusion ◽  
Triggered Activity

The role of gap junction intercellular communication (GJIC) in ischemia-induced focal ventricular tachycardia (VT) is unknown. We have developed a new, stable antiarrhythmic peptide analog named ZP123 that selectively increases GJIC and prevents reentrant VT. Our aim in this study was to use ZP123 as a tool to assess the role of GJIC on occurrence of ischemia-induced focal VT and triggered activity (TA) due to delayed afterdepolarizations (DADs). Focal VT was induced by programmed stimulation in α-chloralose-anesthetized, open-chest dogs 1–4 h after coronary artery occlusion. Three-dimensional activation mapping was done using 6 bipolar electrograms on each of 23 multipolar needles in the risk zone. Dogs were randomly assigned to receive either saline or ZP123 cumulatively at three dose levels (an intravenous bolus followed by a 30-min infusion per dose). Attempts to induce VT were repeated in each dose. Mass spectrometry was used to measure plasma ZP123 concentrations. Standard microelectrode techniques were used for in vitro study of DADs and TA. Twenty-six dogs with focal VT were included. ZP123 did not affect the inducibility of focal VT at any plasma concentrations vs. saline (0.8 ± 0.1 nM, 77 vs. 75%; 7.8 ± 0.4 nM, 86 vs. 77%; and 78.8 ± 5.0 nM, 77 vs. 91%). In vitro, ZP123 did not affect the induction of DADs (12/12) and TAs (10/10) in ischemic tissues or tissue removed from the origin of focal VT (DADs, 8/8; TAs, 4/4). Therefore, although indirect, the data with the doses and concentrations used suggest that GJIC may not play a major role in the genesis of focal activity in the ischemic models studied.

scholarly journals Angiotensin II effects on ischemic focal ventricular tachycardia are predominantly mediated through myocardial AT2 receptor

2009 ◽  
Vol 297 (5) ◽  
pp. H1889-H1898 ◽  
Author(s):  
Rakesh Gopinathannair ◽  
Ashok K. Chaudhary ◽  
Dezhi Xing ◽  
Debra Ely ◽  
Wei Zheng ◽  
...  
Keyword(s):  
Ventricular Tachycardia ◽  
Angiotensin Ii ◽  
Enzyme Inhibitors ◽  
Three Dimensional ◽  
Coronary Artery Occlusion ◽  
Angiotensin Converting Enzyme Inhibitors ◽  
Artery Occlusion ◽  
Converting Enzyme Inhibitors ◽  
Triggered Activity

Ischemic focal ventricular tachycardia (VT) occurs in animals and humans. Angiotensin-converting enzyme inhibitors and receptor blockers reduce sudden death in patients with ischemic heart disease. In our dog model of coronary artery occlusion (CAO), we tested the hypothesis that angiotensin II (AGII) will selectively promote focal VT and that the specific AT2 blocker PD-123319 (PD), or AT1 blocker losartan, will affect this VT. Anesthetized dogs ( n = 90) underwent CAO, followed by three-dimensional activation mapping of inducible VT. Dogs without VT in 1–3 h after CAO received AGII, and those with VT received either PD or losartan. Focal endocardium excised from ischemic sites was studied in vitro with standard microelectrode. Of 33 dogs with no inducible VT, AGII infusion resulted in sustained VT of only focal Purkinje origin in 13 (39%) compared with 0 of 20 dogs with saline. Of 26 dogs with inducible VT at baseline, given PD, reinduction was blocked in 8 of 10 ( P < 0.05) focal VT, but only 1 of 15 with reentry. In contrast, of 11 dogs given losartan, reinduction of either mechanism was not blocked. In vitro triggered activity in Purkinje was blocked by PD in 13 of 19 ( P < 0.05), but not by losartan in 8. Also, triggered activity was promoted by AGII, losartan, or the combination in 9 of 12 tissues. AGII promotes only focal, mainly Purkinje ischemic VT. PD, but not losartan, preferentially blocked focal VT, which is likely due to triggered activity due to delayed afterdepolarizations in Purkinje.

Three-dimensional stiffness in a thoracolumbar en-bloc spondylectomy model: A biomechanical in vitro study

2007 ◽  
Vol 22 (9) ◽  
pp. 957-964 ◽  
Author(s):  
A.C. Disch ◽  
A. Luzzati ◽  
I. Melcher ◽  
K.D. Schaser ◽  
F. Feraboli ◽  
...  
Keyword(s):  
Three Dimensional ◽  
In Vitro Study ◽  
Vitro Study ◽  
En Bloc ◽  
En Bloc Spondylectomy ◽  
Bloc Spondylectomy

scholarly journals Effects of Ethanol and Acetaldehyde on Tight Junction Integrity: In Vitro Study in a Three Dimensional Intestinal Epithelial Cell Culture Model

PLoS ONE ◽  
2012 ◽  
Vol 7 (4) ◽  
pp. e35008 ◽  
Author(s):  
Elhaseen Elamin ◽  
Daisy Jonkers ◽  
Kati Juuti-Uusitalo ◽  
Sven van IJzendoorn ◽  
Freddy Troost ◽  
...  
Keyword(s):  
Cell Culture ◽  
Epithelial Cell ◽  
Intestinal Epithelial Cell ◽  
Three Dimensional ◽  
In Vitro Study ◽  
Intestinal Epithelial ◽  
Cell Culture Model ◽  
Epithelial Cell Culture ◽  
Culture Model

scholarly journals Evaluation and Comparison of Dimensional Accuracy of Newly Introduced Elastomeric Impression Material using 3D Laser Scanners: An in vitro Study

2013 ◽  
Vol 14 (2) ◽  
pp. 265-268 ◽  
Author(s):  
Naveen S Yadav ◽  
Teerthesh Jain ◽  
Amrita Pandita ◽  
SMA Feroz ◽  
Pradeep LNU ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Laser Scanner ◽  
In Vitro Study ◽  
Dimensional Accuracy ◽  
Time Intervals ◽  
Impression Material ◽  
Impression Materials ◽  
Laser Scanners ◽  
Master Model

ABSTRACT Aim Aim of the present study was to comparatively evaluate dimensional accuracy of newely introduced elastomeric impression material after repeated pours at different time intervals. Materials and methods In the present study a total of 20 (10 + 10) impressions of master model were made from vinyl polyether silicone and vinyl polysiloxane impression material. Each impression was repeatedly poured at 1, 24 hours and 14 days. Therefore, a total of 60 casts were obtained. Casts obtained were scanned with three-dimensional (3D) laser scanner and measurements were done. Results Vinyl polyether silicone produced overall undersized dies, with greatest change being 0.14% only after 14 days. Vinyl polysiloxane produced smaller dies after 1 and 24 hours and larger dies after 14 days, differing from master model by only 0.07% for the smallest die and to 0.02% for the largest die. Conclusion All the deviations measured from the master model with both the impression materials were within a clinically acceptable range. Clinical significance In a typical fixed prosthodontic treatment accuracy of prosthesis is critical as it determines the success, failure and the prognosis of treatment including abutments. This is mainly dependent upon fit of prosthesis which in turn is dependent on dimensional accuracy of dies, poured from elastomeric impressions. How to cite this article Pandita A, Jain T, Yadav NS, Feroz SMA, Pradeep, Diwedi A. Evaluation and Comparison of Dimensional Accuracy of Newly Introduced Elastomeric Impression Material using 3D Laser Scanners: An in vitro Study. J Contemp Dent Pract 2013;14(2):265-268.

Helical Rosette Nanotubes as a Potentially More Effective Orthopaedic Implant Material

2004 ◽  
Vol 845 ◽  
Author(s):  
Ai Lin Chun ◽  
Hicham Fenniri ◽  
Thomas J. Webster
Keyword(s):  
Tissue Engineering ◽  
Surface Roughness ◽  
Bone Cells ◽  
In Vitro Study ◽  
Orthopaedic Implant ◽  
Rosette Nanotubes ◽  
Osteoblast Adhesion ◽  
Organic Nanotubes ◽  
First Time

ABSTRACTOrganic nanotubes called helical rosette nanotubes (HRN) have been synthesized in this study for bone tissue engineering applications. They possess intriguing properties for various bionanotechnology applications since they can be designed to mimic the nanostructured constituent components in bone such as collagen fibers and hydroxyapatite (Ca5(PO4)3(OH)) which bone cells are naturally accustomed to interacting with. This is in contrast to currently used orthopaedic materials such as titanium which do not possess desirable nanometer surface roughness. The objective of this in vitro study was to determine bone-forming cell (osteoblasts) interactions on titanium coated with HRNs. Results of this study showed for the first time increased osteoblast adhesion on titanium coated with HRNs compared to those not coated with HRNs. In this manner, this study provided evidence that HRNs should be further considered for orthopaedic applications.

Abstract 12648: Deletion of 12/15 Lipoxygenase Improves Left Ventricle Function and Survival by Resolving Inflammation Post Myocardial Infarction

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Vasundhara Kain ◽  
Kevin A Ingle ◽  
Janusz Kabarowski ◽  
Sumanth D Prabhu ◽  
Ganesh V Halade
Keyword(s):  
Myocardial Infarction ◽  
Left Ventricle ◽  
Survival Rates ◽  
Coronary Artery Ligation ◽  
Artery Ligation ◽  
Lv Remodeling ◽  
Early Expression ◽  
Cox 2

12/15 lipoxygenase (LOX) is crucial in the inflammatory process leading to diabetes and atherosclerosis. However, the role of 12/15 LOX in myocardial infarction (MI) and left ventricle (LV) remodeling is unclear. We assessed the role of 12/15 LOX in resolving inflammation in post-MI LV remodeling. 8-12 weeks old C57BL/6J wild-type (WT; n=67) and 12/15 LOX (LOX –/– ; n=78) male mice were subjected to permanent coronary artery ligation surgery and monitored through day (d)1 and d5. No MI surgery mice were maintained as d0 naïve controls. LOX -/- mice showed higher survival rate, improved fractional shortening with reduced remodeling and edema index than WT at d1 and d5 post-MI (all p<0.05). LOX -/- mice showed increased Cxcl5 expression at d1 post-MI, consistent with stimulated neutrophil recruitment in the infarct region that was decreased at d5 compared to WT. LOX -/- mice infarct had increased expression of Ccl2 and Cxcl1, that stimulated an earlier recruitment of monocytes with increased macrophages population at d5 (all p<0.05) compared to WT. The altered kinetics of immune cells post-MI indicates a rapid resolving phase, through increase in alternative macrophage phenotypes with reduced collagen density in LOX -/- mice compared to WT mice at d5 post-MI. LOX -/- mice showed a coordinated COX-1 and COX-2 response at d1 post MI, leading to an evident increase in 5-LOX and hemoxygenase-1 (HO-1) at d5 post-MI. 12/15 LOX deletion enhanced the recruitment of alternative macrophages with secretion of HO-1 to resolve inflammation. In-vitro addition of LOX metabolite 12 hydroxyeicosatetraenoic acid to LOX -/- fibroblast induced early expression of COX-2 and 5-LOX compared to WT, indicating 5LOX role in resolution of inflammation. Post-MI increased expression of TIMP-1 and decrease in MMP-9 at d1 and α-SMA at d5 in LOX -/- mice suggested controlled differentiation of fibroblast-to-myofibroblast which is key event during ventricular tissue repair and resolving phase. This change is supported by increased expression of tgf-βi, ctgf and admats-2 (all P<0.05) at d5 post MI. In conclusion, absence of 12/15 LOX improves post-MI survival rates and attenuates LV dysfunction by resolving inflammation through coordination of 5-LOX and HO-1 as key inflammation resolving enzymes.

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