Influence of epicardial stenosis severity and central venous pressure on the index of microcirculatory resistance in a follow-up study.
OBJECTIVE
This study sought to evaluate the reproducibility of the index of microcirculatory resistance (IMR) in a follow-up model and the role of epicardial artery stenosis and central venous pressure (Pv) on IMR.


RESULTS
Twenty-two patients with stable coronary artery disease underwent coronary catheterisation at baseline and after seven weeks. The IMR was calculated at baseline and follow-up in several ways: as IMRuncorrected=Pd·Tmn (Pd: intracoronary pressure distal to the stenosis; Tmn: transit mean time); IMRcorrected=Pa·Tmn·(Pd - Pw)/(Pa-Pw), (Pw: coronary wedge pressure; Pa: aortic pressure); and as IMRcentral venous pressure (IMRcvp)=(Pa-Pv)·Tmn·(Pd-Pw)/(Pa-Pw). By neglecting Pw, IMR was overestimated irrespective of the haemodynamic severity of the epicardial stenosis (baseline: IMRuncorrected=15.5±8.9 U vs. IMRcorrected=13.5±8 U, p<0.001; follow-up: IMRuncorrected=16.9±4.9 U vs. IMRcorrected=13.8±4.6 U, p<0.001). In the intra-individual analysis IMR did not differ between the two time points. The IMRcvp equalled the IMRcorrected at all time points.


CONCLUSIONS
IMR is a reproducible index in follow-up studies, independent of any overestimation existing when collateral flow status is neglected. Pv can be neglected for calculation of the IMR.
Arteriogenesis Research Group, Center for Cardiovascular Research (CCR) & Department of Cardiology, CVK, Charité - Universitätsmedizin Berlin, Berlin, Germany.
Nikolaos
N
Pagonas
C Michael
CM
Gross
Mejing
M
Li
Anja
A
Bondke
Volker
V
Klauss
Eva-Elina
EE
Buschmann
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002496:Central Venous Pressure / Q000502:physiology*; D003097:Collateral Circulation / Q000502:physiology; D003326:Coronary Circulation / Q000502:physiology*; D023921:Coronary Stenosis / Q000601:surgery*; D003331:Coronary Vessels / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D008875:Middle Aged; D012720:Severity of Illness Index; D014655:Vascular Resistance / Q000502:physiology*