Peroperative Hemodynamic Study of Left Internal Mammary Artery Grafts

Y. A. G. Louagie; J. P. Haxhe; J. Jamart; O. Gurne; M. Buche; J. C. Schoevaerdts

doi:10.1055/s-2007-1013764

The Thoracic and Cardiovascular Surgeon, Table of Contents

Thorac Cardiovasc Surg 1995; 43(1): 27-34
DOI: 10.1055/s-2007-1013764

Peroperative Hemodynamic Study of Left Internal Mammary Artery Grafts

Intraoperative hämodynamische Studien an A. mammaria-TransplantationenY. A. G. Louagie¹ , J. P. Haxhe¹ , J. Jamart² , O. Gurne³ , M. Buche¹ , J. C. Schoevaerdts¹

¹Division of Cardiovascular and Thoracic Surgery of the University Hospital of Mont-Godinne (Catholic University of Louvain), Yvoir, Belgium
²Division of Biostatistics of the University Hospital of Mont-Godinne (Catholic University of Louvain), Yvoir, Belgium
³Division of Cardiology of the University Hospital of Mont-Godinne (Catholic University of Louvain), Yvoir, Belgium

Abstract

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Summary

The present study was undertaken to analyse hemodynamic features of an arterial graft and to determine parameters which influence primarily flow and velocity.

A total of 284 consecutive patients having isolated coronary bypass surgery underwent peroperative hemodynamic assessment by pulsed Doppler ultrasonics of a left internal mammary artery bypass graft implanted onto the left anterior descending artery.

Internal mammary artery free flow was 109.2 ± 3.7 ml/min and flow in the internal mammary artery measured after completion of the distal anastomosis was 70.9 ± 2.7 ml/min. All values quoted are mean ± standard error of the mean. Mean velocity was 21.2 ± 0.6 cm/sec, internal diameter was 2.65 ± 0.04 mm and pulsatility index was 2.24 ± 0.12. Resistance was expressed as mmHg/(ml . min^-1) and averaged 1.65 ± 0.13 for total resistance, 0.87 ± 0.05 for graft resistance, and 0.73 ± 0.13 for coronary resistance. From a set of 35 variables, stepwise multiple regression analysis selected two parameters influencing independently flow in internal mammary artery (R² = 0.8762): flow velocity (p < 10^-4) and internal diameter (p < 10^-4). Variables influencing velocity (R² = 0.3071) were: pulsatility index, which is a dimensionless expression of peripheral resistance (p < 10^-4), and free internal mammary artery flow (p = 0.0007). Furthermore, a significant correlation between internal diameter and total resistance was observed (R = - 0.5363, p < 10^-4, Y = 1.676 X^-1.545), and the exponentially fitted regression line was characterized by a marked increase of resistance at diameters less than 2 mm.

Flow in grafted internal mammary arteries was predominantly influenced by the internal diameter of the graft and by velocity, which was related to peripheral resistance. Total resistance, as measured in the graft, increased in an exponential way with the reduction of graft internal diameter.

An 284 Patienten, die sich einer isolierten koronarchirurgischen Bypass-Operation unterzogen, wurden mittels gepulster Doppler-Methode hämodynamische Untersuchungen vorgenommen. Der freie Blutfluß der A. mammaria interna betrug 109,2 ± 3,7 ml/min, nach Implantation in die LAD betrug er 70,9 ± 2,7 ml/min. Die mittlere Flußgeschwindigkeit betrug 21,2 ± 0,6 cm/sec, der innere Durchmesser 2,65 ± 0,04 mm und der Pulsindex war 2,24 ± 0,12. Der Transplantat-Widerstand betrug 0,87 ± 0,05 mmHg x ml^-1 x min^-1, der Koronargefäßwiderstand 0,73 ± 0,13, der totale Gefäßwiderstand 1,65 ± 0,13. Aus den Untersuchungen geht hervor, daß der Fluß im Mammaria-Transplantat hauptsächlich von seinem inneren Durchmesser und von der Flußgeschwindigkeit abhängt, die ihrerseits vom peripheren Widerstand abhängt.

Key words

Coronary artery surgery - Internal mammary artery - Flow - Pulsed Doppler

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