Bauer, Barbara

Kloner, Robert A.

Przyklenk, Karin

Elsevier - Publisher Connector 

118A ABSTKACTS 
JAW Vol 17. No. 1 
Fchruarv '1991:118A 
11:lS 
PARISON OF 2-ELEUENT AND S-ELEUENT ELS FOR 
ESTIMTION OF ARTERIAL VISCOEMSTIC PARAMETERS 
Gary McCray, Richard Marcus, Mark Lavenant, Claudia 
Korcarz, Pinhas Sareli, Roberto Lang, U. of Chicago, IL 
Arterial stiffness results from the combined effects of 
compliance (C) and viscosity (V). Compliance estimates 
obtained using the currently favored P-element 
Windkessel model, which ignores V, may be inaccurate. 
Accordingly, we used a 3-element model to estimate both 
these parameters from aortic root pressure and flow 
data. Instantaneous aortic pressure and flow 
measurements were obtained in 7 patients using Millar 
microtin catheters and intravascular electromagnetic 
flow probes, calibrated by thermodilution card'lac 
outouts. Values for (i) C alone (for the P-element 
. . ..-.__ r _-. - 
model) and (ii) C and i, (for the 3-element. model) were 
computed by an fterative procedure designed to identify 
parameter values which minimize the error function (D, 
the absolute average difference between measured and 
model pressure waveforms). 2-element model values for C 
and 3-element model values for C and V are shown below 
together with D values for both models. Values are 
SD. *p=<.Ol, paired t test. 
P-e1 a 
9) .73 
et/cc) 
7.1:1 6 
.082+.023 
2+1.1* 
C values for the 2-eleient model are lower than values 
for the 3-element model. The error function is higher 
for the P-element model than for the J-element model. 
Conclusion: (i) The 3-element model, which incorporates 
both compliance and viscosity, describes the arterial 
pressure-flow relationship more accurately than the 2- 
element model. (ii) The 3-element model should be used 
for estimation of arterial viscoelastic parameters. 
1 I:30 
ROLE OF ASYNCHRONY ON REGIONAL LEFT VENTRICULAR 
DIASTOLIC FUNCTION IN EXERCISING DOGS WITH ISCHEMIA 
Shunichi Mivazaki, Brian D. Guth, Toshiro Miura, Ciro Indolfi, 
and John Ross Jr. 
University of California, San Diego, La Jolla, CA 
Effacts of asynchronous wall motion (ASN) on regional diastolic 
function were examined in 7 conscious dogs instrumented with 
micromanometer for Left ventricular (LV) pressure (P) and 
sonomicrometers for anterior and posterior (AT and PT) wall 
thickness. After recording steady sate exercise (UC), ischemia 
(I) was created during EX (EX-I) by a pneumatic occluder on 
the left circumflex coronary artery. The AT and PT time 
difference CT-ASN) between peak thickening was measured as 
an index of ASN. From pressure-wall thickness loops of AT 
(LoopAT), loop areas were calculated as indices of regional 
myocardial work. From EX to EX-I, peak LVP decreased by 
11% and T-ASN increased from 19.7-c 14.7 to 42.9-c 11.3 msec 
(pcO.01). accompanied by marked deformation of IoopAT in AT 
during relaxation (Figure), which was related to impaired 
relaxation in PT. LoopAT area decreased (pcO.OS), reflecting in 
part passive AT wall deformation during relaxation. LV relaxation 
was impaired (increased time constant of LVP decav from 
14.022.7 to 17.023.9, r 
w  
~~0.05). Conclusion: During exercise 
induced ischemia, abnormal passive 
wall motion in normal regions 
produced marked asynchrony and 
contributed importantly to impaired 
global LV relaxation. 
II:45 
EARLY BUT TRANSIENT POSTISCHEMIC CONTRACTION: 
A RELIABLE INDICATOR OF VIABLE MYOCARDIUM? 
&wilt Pr:vklenk. Barbara Bauer and Robert A. Kloner. Heart 
Institure, Hospital of the Good Samarilan and USC. Los Angeles. CA. 
Timely administration of thrombolytic agents is aimed at limiting 
infarct size, yet immediate and reliable clinical indicators of 
salvaged vs. necrotic myocardium are lacking. Using an anesthetized 
open-chest canine model, we sought to determine whether myocardial 
contractility measured postreperfusion could be used as a ‘predictor’ 
of viable vs. necrotic tissue. Ten dogs underwent 3 h of coronary 
occlusion (CO) followed by 3 h of reperfusion. Segment shortening 
(Ss: an index of regional contractile function) was assessed in the 
ischemic/reperfused midmyocardium of all dogs and expressed as a % 
of baseline, preC0 values. Five animals were severely ischemic 
during occlusion (mean endocardial blood flow of .02+.01 ml/min/g) 
and developed large infarcts (55k9% of the risk region), while 5 dogs 
had extensive collateral perfusion (endocardial blood flow of .31+.05 
ml/min/g) and developed virtually no necrosis (422%). Large vs small 
infarcts could not be dis- 
PretO lh 3h 5’ lh Jh 
I post reflow (*+p<O.O5 vs 
Infarc: Size: Large 
large infarcts and ++p<O.O5 
vs 3 hours DostCO). In 
O-----O Small contrast, there was no 
evidence of improved SS in dogs with large infarcts. This early but 
transient improvement in contractile function immediately afrer 
reperfusion may therefore provide a useful method to distinguish 
viable (but stunned) vs. necrotic myocardium. 
10:30 
20-YE9 RESULTS OF CORONARY BYPASS SURGERY FOR ANGINA 
Shahbudin Ii. Rahimtoola, Cindy Fessler, Gary L. 
Grunkemeier, Albert Starr. The Heart Institute at St. 
Vincent Hospital and Medical Center, Portland, Oregon. 
From 1969 to 1988, 238 of 8182 patients (Pts) who 
underwent coronary bypass surgery (CBS) for angina died 
within 1 month (2.9%). The 20-year survival for the 
entire series was 3823.3 yrs. It was lower for those 
with 3-vessel disease and for those with abnormal left 
ventricular function. 
Pts were grouped by year of operation: (A) 1969-73, 
mean age 54 yx ‘5. ; (B) 1974-78, 58 yrs.; (C) 1979-83, 61 
yre.; (D) 1984-88, 64 yrs. Group A had the best Pt 
characteristics but lowest operative and long-term 
survival, indicating 1969-73 was a period of major 
development towards optimization of CBS. 
Groups D. C. and B had similar S-year survival, and 
Groups C and B had similar IO-year survival. The annual 
mortality for Group B+C (4564 Pts) was relatively linear 
at 2.5Xlyear up to 10 years and increased to 3.6Xlyear 
after 10 years. The increase in mortality after 10 years 
occurred In most subsets of Pts. Reoperation rates were 
<1X, 2.4% and 3.4% per year for years 1-5, 6-10 and 11-15 
after CBS. In the years 16-20 after CBS, 75% of Pts have 
no angina or mild angina. 
We conclude that results of CBS for angina are most 
satisfactory for up to 20 years. After 10 years, 
mortality and reoperation rates are increased and are 
likely a reault of 
of disease, 
bhe advancing age of Pts, progression 
development of new disease and long-term 
effects of abnormal left ventricular function. 


Early but transient postischemic contraction: A reliable indicator of viable myocardium? 

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Early but transient postischemic contraction: A reliable indicator of viable myocardium?

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