The mechanisms involved in the progression of heart failure includes cardiomyocyte death, initiation of the inflammatory response, and subsequent formation of a fibrotic scar. For this reason, diverse experimental models, such as cultured cardiac cells, isolated hearts, and animal models, have been created to mimic human myocardial infarction and heart failure. In a 2012 Scientific Statement from the American Heart Association, permanent coronary artery ligation was deemed clinically relevant and a significant model for ischemic heart failure. The variability in coronary artery anatomy and branching of the left coronary artery can affect reproducibility of MI surgery, even with occlusion at a constant anatomic site. Blanching and LV discoloration are common variables used to confirm successful MI surgery. Determining a way to improve precision will improve the standard surgical approaches to simulate MI in mice, thus reducing the number of experimental animals necessary for statistically relevant studies. In this webinar, we will discuss the advantages of using electrocardiography to verify correct ligation. Learning objections Summary of my lab goals Timeline of inflammation after permanent occlusion Intro to MI surgical model

1. Kristine DeLeon-Pennell, Ph.D
Assistant Professor
Department of Medicine
Medical University
of South Carolina
Using EKG to Confirm MI in
Mouse Model of Permanent
LAD Occlusion

2. Audience Poll

3. Using EKG to confirm MI
in mouse model of
permanent LAD
Kristine Y DeLeon-Pennell, Ph.D
10-8-2020

4. DeLeon-Pennell Lab Focus

5. Cardiovascular Disease is the number one killer in
the US

6. Myocardial Infarction
• Approximately
every 40 seconds,
an American will
have a heart attack
• Average age at the
first heart attack is
65.6 years for men
and 72.0 years for
women

7. Wound healing is spatial
and temporal dependent
DeLeon-Pennell, Yabluchanskiy et al. 2014

8. CD8 T-cells are present within the infarct
Yan et al. JMCC. 2013

9. CD8atm1Mak improved day 7 survival
*p<0.05 vs WT
Ilatovskaya et al. AJP-Heart 2018

10. CD8atm1Mak improved
day 7 cardiac function
*p<0.05 vs WT
Ilatovskaya et al. AJP-Heart 2018
30
20
10
0
WT CD8atm1mak
EF(%) 30
20
10
0
WT CD8atm1mak
FS(%)
* *

11. CD8atm1Mak ↑ fibrosis post-MI
*p<0.05 vs respective baseline (D0); †p<0.05 vs WT D3; ‡p<0.05 vs CD8atm1Mak D3.
Ilatovskaya et al. AJP-Heart 2018

12. CD8atm1Mak ↓ collagen cross-linking post-MI
*p<0.05 vs respective baseline (D0); †p<0.05 vs WT D3; ‡p<0.05 vs CD8atm1Mak D3.
Ilatovskaya et al. AJP-Heart 2018

13. CD8atm1Mak ↑ Th1 cells
at day 3 post-MI
*p<0.05 vs respective baseline (D0); †p<0.05 vs WT D3; ‡p<0.05 vs CD8atm1Mak D3.
Ilatovskaya et al. AJP-Heart 2018

14. CD8atm1Mak ↑ innate immune response at day 3
post-MI
*p<0.05 vs respective baseline (D0); †p<0.05 vs WT D3; ‡p<0.05 vs CD8atm1Mak D3.
Ilatovskaya et al. AJP-Heart 2018

15. CD8 T-cells may be both beneficial and detrimental
for post-MI wound healing
Ilatovskaya et al. AJP-Heart 2018

16. Introduction to permanent
occlusion MI surgical model

17. Permanent occlusion MI surgery
Zamilpa et al. Methods Mol Biol. 2013
Incision and
identification of
the muscle layers
covering the rib
cage

18. Permanent occlusion MI surgery
Zamilpa et al. Methods Mol Biol. 2013
Retraction of
muscle layers and
location of the third
intercostal space

19. Permanent occlusion MI surgery
Zamilpa et al. Methods Mol Biol. 2013
Position of the
gauze to protect
the lungs and
assist with the
intercostal incision

20. Permanent occlusion MI surgery
Zamilpa et al. Methods Mol Biol. 2013
Position of LAD
ligation with
respect to left
atrium

21. Permanent occlusion MI surgery
Zamilpa et al. Methods Mol Biol. 2013
Position of LAD
ligation with
respect to left
atrium

22. Permanent occlusion MI surgery
Zamilpa et al. Methods Mol Biol. 2013
Suturing the skin
incisions

23. Audience Poll

24. Using EKG to confirm
successful MI

25. Ways to visually confirm MI
• Visual changes
– LV blanching
– Lack of movement in the apex
Zamilpa et al. Methods Mol Biol. 2013

26. Problems visualization of MI
• Variation in infarct size/too small MI
– 35% infarct as cut off
– Miss the LAD and only get a branch
– Anatomical differences between animals
– Can’t see the LAD clearly

27. Measuring infarct size
*p<0.05 vs WT
WT CD8atm1Mak
TTC Images
2,3,5-Triphenyltetrazolium chloride
WT CD8atm1Mak
80
60
40
20
0
InfarctSize
p = 0.37
Ilatovskaya et al. AJP-Heart 2018

28. Using EKGs to confirm MI
• EKG predicted the severity of
the MI damage (Preda et al.
Comp Med 2010)
– ST height elevation (204
compared with 14 μV)
– QTc prolongation (136
compared with 76 ms)
Pre-ligation After ligation
ST
segment
ST
segment
elevation

29. Using Rodent Surgical Monitor

30. QRS-T area changes after MI surgery
p=0.008
10
7.5
5.0
2.5
0
Pre Post
QRS-T Area
mV/ms
Pre-ligation After ligation

31. ST elevation change after MI surgery
p=0.009
0
-0.5
-1.0
-1.5
Pre Post
ST interval
mV
Pre-ligation After ligation

32. Using EKGs to confirm MI
p=0.0560.75
0.50
0.25
0
MI No MI
ST interval
mV;post-preMI
100
75
50
25
0
0 25 50 75 100
Sensitivity(%)
Specificity (%)
Area=0.843
p=0.062

33. Does time matter?
https://ecgwaves.com/topic/the-ecg-in-assessment-of-reperfusion/

34. Acknowledgments
This work was supported by the
American Physiological Society and
S&R Foundation Ryuji Ueno Award;
MUSC’s Specialized Center of
Research Excellence (SCORE) on Sex
Differences; Biomedical Laboratory
Research and Development Service of
the Veterans Affairs Office of Research
and Development Award IK2BX003922.
Current Lab Members:
Miguel Troncoso, Yusra Zaidi
Past Lab Members:
Reed Studer, Jada Cameron, Joshua
Clayton, Cooper Pitts, Jonathan
Ortega, Sarah Pippin, Megan
Douglass, Pranav Tyagi, John Martino

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Q&A
SESSION:
Kristine DeLeon-Pennell, Ph.D
Assistant Professor
Department of Medicine
Medical University
of South Carolina