Influence of Different Harvesting Techniques on the Arterial Wall of the Internal Mammary Artery Graft: Microscopic Analysis

 

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Summary

An histological comparison was made between left internal mammary arteries (LIMAs) harvested and prepared with different techniques prior to coronary artery bypass grafting. The mobilization of LIMA was made as follows: conventional technique (group I), extra pleural takedown with lysis of the endothoracic fascia (group II), and LIMA skeletonization (group III). Each group was divided into two other sub-groups according to the LIMA graft preparation: papaverine-saline Solution sprayed on the pedicle (sub-group A) and intraluminal hydrostatic dilatation (sub-group B).

Free blood flow from the LIMAs was measured immediatly before cardipulmonary bypass and Ultrasonic duplex scanning (UDS) was performed to analyze the flow patterns and velocities during the early postoperative course.

The results showed that the technique by which the LIMA is harvested bears no significant relationship to microscopical graft damage, while intimal lesions were observed in all subgroups that adopted intraluminal hydrostatic dilatation (subgroup B). No difference in intraoperative LIMA flows were noted between groups and sub-groups of patients except in the case of group I-sub-group B, in which the flow was markedly roduced.

Intramural hacmatoma or subadventitial blood effusion was observed with low incidence and magnitude in all groups and subgroups of patients, without any roduction of blood flow, and all LIMAs were patent at UDS measurements.

In conclusion, the results showed that the method by which the IMA is harvested bears little and insignificant relationship to arterial wall damage.

Although intraluminal hydrostatic dilatation and LIMA catheterization may produce some microscopic lesions to the internal elastic lamina and foci of intimal dissection, signs of intraoperative or early postoperative blood flow deficit were not recorded.

Zusammenfassung

Das Ziel der vorliegenden Studie war herauszufinden, ob unterschiedliche Techniken der Gewinnung und Präparation der A.thoracica interna zu Wandschäden dieses Gefäßes führen. Zu diesem Zweck wurden von 70 Koronarpatienten vor Beginn der EKZ distale Segmente der linken A.thoracica int. entnommen. Es wurden drei verschiedene Techniken angewandt: I die konventionelle Präparation, II extrapleurale Entnahme mit Ablösung der Fascia endothoracica und III Skelettierung des Gefäßes. Jede dieser drei Gruppen wurde unterteilt in 2 Untergruppen: in Gruppe A wurde der Gefäßstiel mit einer Papaverin-Lösung besprayt und in Gruppe B wurde das Gefäßlu men mit einer verdünnten Papaverin-Lösung unter hydro statischem Druck dilatiert.

Es fanden sich keine Unterschiede des intraoperativen Flow in den verschiedenen Gruppen, mit Ausnahme der Gruppe I B, in der der Flow erheblich reduziert war. Die histologischen Untersuchungen zeigton deutliche Wandschäden nur in den B-Gruppen (intraluminäre Gefäßdilatation), während sonst keine Unterschiede zwischen den verschienen Präparationsgruppen I, II und III zu finden waren; hinsichtlich des Offenbleibens der Gefäße in der frühen postoperativen Phase war auch kein Unterschied zwischen den Gruppen I, II und III festzustellen.