Using swine model to perform correlations of QA interval with end systolic elastance using quadratic and linear curve fitting. Also intricacies of how to best capture A in the QA interval are described.

1. CARDIAC CONTRACTILITY USING QA INTERVAL
CORRELATIONS TO END SYSTOLIC ELASTANCE (QUADRATIC AND LINEAR FIT )
INTRICACIES HOW TO BEST CAPTURE POINT A AT (QA INTERVAL)
Swine hemodynamic modeling by
Filip Konecny

2. SWINE CATHETERIZATION OF ASCENDING AORTA AND LEFT
VENTRICLE, ECG SURFACE ELECTRODE PLACEMENT
BALLOON CATHETER (IVC OCCLUSION)
Using isoflurane gaseous anesthesia, swine’s (n=12) right carotid artery (LV access) and left carotid artery
(ascending aortic access) was set up using a percutaneous technique.
Balloon catheter, percutaneously accessing the left femoral vein (LFV) was used to perform inferior caval vein
(IVC) occlusions to temporary decrease LV preload, obtaining load-independent values of contractility including
End systolic elastance, Vo volume axis intercept.
Surface 5 lead electrode ECG system was set up while continuously monitoring during insertion of PV and
pressure catheters. Later, data were simultaneously captured using recording of 400 samples/sec.
All animals were compared using physiological HR.
Data files followed an example of QA interval in dog published in article by Pugsley MK et al. An evaluation of
the utility of LVdP/dt40, QA interval, LVdP/dtmin and Tau as indicators of drug-induced changes in contractility
and lusitropy in dogs. J Pharmacol Toxicol Methods. 2017 May - Jun;85:1-21. doi:
10.1016/j.vascn.2017.01.002. Epub 2017 Jan 5.

3. 1. Area of QA interval as contractility measurement using LOAD DEPENDENT data
(non-preload reduction)
2. Area of LV dp/dt @40mmHg as contractility measurement using LOAD
DEPENDENT data (non-preload reduction)
3. Area of ESPVR as contractility measurement using LOAD INDEPENDENT (Ees, V0,
SSE) by quadratic fit (preload reduction)
4. Area of ESPVR as contractility measurement using LOAD INDEPENDENT (Ees, V0,
SSE) linear fit (preload reduction)
4 main areas where considered, compared and contractility data were
correlated

4. EXAMPLE OF QA COLLECTED FROM ANIMALS (LOAD-DEPENDENT)
Time 1-Time 2 = 70msec

5. EXAMPLE of LV dp/dt @40mmHg COLLECTED FROM ANIMALS (LOAD-DEPENDENT)
Value of LV dp/dt@40mmHg = 2194.022 mmHg/sec

6. EXAMPLE of ESPVR using quadratic fit
TEMPORARY PRELOAD OCCLUSION (IVC) LOAD-INDEPENDENT
ESPVR:
Equation: P = -0.134338*V^2 + 11.835460*V + -180.785)
SSE Value = 20.512
Intercept(V0) = 19.664
ESPVR slope Ees (sqrt(b2_4ac)) = 6.552
HR 111 bpm

7. EXAMPLE of ESPVR using linear fit
TEMPORARY PRELOAD OCCLUSION (IVC) LOAD-INDEPENDENT
ESPVR:
Equation: P = 2.177138*V + -13.567051
R Value = 0.955
SSE = 391.310
Intercept(V0) = 6.232
ESPVR slope (Ees) = 2.177
HR 111bpm

8. End systolic elastance, using quadratic fit (slope Ees), Intercept (V0) and SSE value
PLEASE NOTE: Each point in the PV loop where the Maximal PV ratio occurs is called end systolic elastance (i.e. for each loop) as at this point the ratio of P vs. V is referred as LV chamber
elastance. Connecting all these point we can create in this e.g. curve-linear slope relationship called Ees. The sum of squares due to error SSE further characterizes the curve-linear fit. Naturally,
correlating LVP with LVV should provide succinct information about chamber elastance as LV is getting emptied through blood leaving via aorta. As we are selecting these individual points we need
to obtain reasonable goodness of fit for given preload reduction(s). The volume axis Intercept (V0) plays a role in acknowledging as to WHERE the chamber's minimal volume lies if hypothetically
we lower LV chamber's pressure to the minimum P0.
In many cases agreement should be in place that when chamber is getting emptied by preload reduction, by IVC occlusion the IC or V0 should be assigned to a non-negative number (volume). If e.g.
during P0, there is sudden LV volume decrement through e.g. a vigorously performed IVC occlusion, that would be causing LV suction in this specific case, IC or V0 can be a negative number. It is
advisable to repeat IVC occlusion multiple times to make sure that goodness of fit is within reasonable range and V0 at P0 correlation is inquired for multiple times before making final
conclusion(s). Table on next slide show how to compare all data.

9. LATER ALL VALUES WERE TABULATED AND
COMPARED

10. value Mean SD n P value
QA (msec) 72.9 9.64 12 NA
HR QA bpm 93.75 23.58 12 0.78
Dp/dt
@40mmHg
(mmHg/sec)
1716.08 568.06 12 NA
HR dp/dt
@40mmHg
(bpm)
96.416 22.42 12 0.78
QA vs. LV dp/dt @40 mmHg
Correlation of load dependent vs. load-dependent values
Graph of QA vs. LV dp/dt@40mmHg. Plotted were LV dp/dt@40mmHg values on Y axis
while on X axis were plotted QA values; all from the same animals. Negative correlation
value of -0.777 was calculated. HR for both, Ees and QA were not significantly different
(p=0.78); n=12, please see table.

11. value Mean SD n P value
QA (msec) 72.9 9.64 12 NA
HR QA (bpm) 93.75 23.58 12 0.77
Ees 4.35 1.9 12 NA
HR Ees (bpm) 96.42 23.58 12 0.77
QA vs. Ees (fit to quadr eq.)
Graph of QA vs. Ees (End systolic elastance). Plotted were Ees slopes calculated using
quadratic fit; values of Ees are plotted on Y axis while on X axis were plotted QA values;
all from the same animals. Negative correlation value of -0.6077 was calculated. HR for
both, Ees and QA were not significantly different (p=0.77); n=12, please see table.
Correlation of load dependent vs. load-independent values

12. QA vs. Ees (fit to lin eq.)
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
0 20 40 60 80 100
Eesslopevalues(lineareq.fit)
QA (msec)
QA vs. Ees (slope fit to linear eq.)
QA vs. Ees linear
Linear (QA vs. Ees
linear)
r = - 0.4067
Graph of QA vs. Ees (End systolic elastance). To plot Ees values, Ees slopes
values were calculated using linear equation. Ees values are plotted on Y axis
while on X axis were plotted QA values from the same animals. Negative
correlation value of -0.4067 was calculated. HR for both, Ees and QA were not
significantly different (p=0.7); n=12, please see table.
value Mean SD n P value
QA (msec) 72.9 9.64 12 NA
HR QA (bpm) 93.75 23.58 12 0.7
Ees 1.58 0.97 12 NA
HR Ees (bpm) 96.5 22.54 12 0.7

13. QA VALUE CAPTURE INTRICACIES
How to improve capture of Ao diastolic pressure point?
Values for A, B and C were different (in msec) based on where Ao
diastolic pressure point cursor was placed (please see on next
slides)
Hence interval of A=60, B=65 and C=70 msec could be obtained

14. How to capture better Ao diastolic pressure point
A B
C A=QA (60msec) B=QA (65msec) C=QA (70msec)

15. Where do you place the cursor on Ao diastolic pressure to obtain A (point in QA)?
Can LV dp/dt max overlay help with A point detection?
Using channel OVERLAY?
On the next slide all 4 channels has been overlaid while red cursor marker stayed on the Q and secondary
red marker cursor has been moved to A=60, B=65 and C=70 msec to obtain these 3 time-QA intervals.
Scale for all channels has stayed the same
Red arrow on overlaid images A, B and C points to Ao diastolic pressure point
Data shows that the best point of Ao valve opening (point A in QA interval) being to a great extent
associated the with the LV dp/dt max in images A=60msec. blue circle above dp/dt max
Can channels overlay, specifically using LV dp/dt max overlay, help capturing A point in QA interval?

16. Channelscales
A
B
C
In the example A, red arrow point to Ao valve
opening associated the best with the LV dp/dt max.
blue circle above dp/dt max
Cardiac Contractility using QA interval / correlations to End systolic
elastance (quadratic and linear fit) and intricacies how to best capture
point A at (QA interval). Konecny F. Feb. 1, 2018 (slides) DOI:
10.13140/RG.2.2.25676.51842