Change of sternal perfusion following preparation of the internal thoracic artery--a scintigraphical study

Today the internal thoracic artery (ITA) is the bypass graft of choice due to its superior long-term patency rate. It was the aim of this present prospective study to investigate possible perfusion disturbances and consecutive impaired wound healing induced by the ITA preparation. The sternal perfusion was assessed by bone scintigraphy.

Forty-four patients were included in the study. There were three groups: group I (control, no ITA preparation; n = 12); group II (preparation of the left ITA; n = 21); group III (preparation of both ITAs; n = 11). In all patients a median sternotomy was performed. A bone scintigraphy was performed 4 days before and 12 days after the bypass procedure. Scintigraphical pictures of all patients were assessed visually (one specialized investigator) and the impulse rate was counted by the aid of a computer program.

Results of both evaluation methods showed congruently that neither the use of the left nor of both ITAs causes a statistically significant impairment of sternal perfusion. The percentage of postoperative increase of the rate of impulses was in group I: total sternum 55%; right side 56%; left side 55%. The respective numbers for group II were 58, 63 and 53%, and for group III 54, 52 and 56%. Surprisingly, perfusion scans in group II revealed an increase in the right sternal half after left ITA preparation. This may be due to the additional blood flow demand of collaterals branching between the right ITA and contralateral intercostal arteries representing a compensatory mechanism of the loss of the left ITA. During the observed postoperative time frame (mean 15 days) no healing disturbance of the sternal wound occurred in any patient.

According to the present data the use of one or both ITAs does not cause an increase of healing disturbances, consecutive to a postoperatively decreased sternal blood perfusion.