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BackgroundThe morphological and functional differences between arteries and veins may have implications on coronary artery bypass graft (CABG) survival. Although subjective differences have been observed between radial artery (RA) and long saphenous venous (LSV) grafts, these have not been quantified. This study assessed and compared the flow characteristics and in-vivo graft flow responses of RA and LSV aorto-coronary grafts.MethodsAngiograms from 52 males taken 3.7 ± 1.0 months after CABG surgery were analyzed using adjusted Thrombolysis in Myocardial Infarction (TIMI) frame count. Graft and target coronary artery dimensions were measured using quantitative coronary angiography. Estimated TIMI velocity (VE) and volume flow (FE) were then calculated. A further 7 patients underwent in-vivo graft flow responses assessments to adenosine, acetylcholine and isosorbide dinitrate (ISDN) using intravascular Doppler.ResultsThe VE for RA grafts was significantly greater than LSV grafts (P = 0.002), however there was no difference in volume FE (P = 0.20). RA grafts showed positive endothelium-dependent and -independent vasodilatation, and LSV grafts showed no statistically significant response to adenosine and acetylcholine. There was no difference in flow velocity or volume responses. Seven RA grafts (11%) had compromised patency (4 (6%) ≥ 50% stenosis in the proximal/distal anastomoses, and 3 (5%) diffuse narrowing). Thirty-seven (95%) LSV grafts achieved perfect patency and 2 (5%) were occluded.ConclusionThe flow characteristics and flow responses of the RA graft suggest that it is a more physiological conduit than the LSV graft. The clinical relevance of the balance between imperfect patency versus the more physiological vascular function in the RA graft may be revealed by the 5-year angiographic follow-up of this trial.

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Background-The pulmonary autograft operation (the Ross procedure) involves excision of a portion of the right ventricular (RV) outflow tract, prolonged cross-clamp times, and insertion of a pulmonary homograft. There is concern about the effect of such operations on right ventricular function. Methods and Results-Twenty-five patients undergoing either pulmonary autograft or homograft replacement of the aortic valve as part of a prospective randomized trial had echocardiographic RV long-axis measurements performed before surgery and 6 months (range 3 to 12 months) after surgery. In all patients, systolic excursion (SE) and both shortening and lengthening rates (SR and LR, respectively) were reduced postoperatively (PϽ0.05) (homografts: SE 1.5Ϯ0.4 versus 2.3Ϯ0.6 cm, SR 6.8Ϯ2.1 versus 9.6Ϯ3.1 cm/s, LR 6.0Ϯ1.8 versus 8.9Ϯ3.0 cm/s; autografts: SE 1.4Ϯ0.4 versus 2.2Ϯ0.4 cm, SR 5.8Ϯ3.0 versus 8.2Ϯ3.0 cm/s, LR 5.7Ϯ1.9 versus 8.5Ϯ3.7 cm/s). There were no differences between the 2 groups. Eighteen patients who had undergone either aortic homograft or pulmonary autograft surgery were studied between 6 and 35 months after surgery. RV volumes were assessed with the use of MRI in addition to echocardiographic RV long-axis measurements. Global volumes were increased to a similar amount in both groups (homografts: end-diastolic volume 145Ϯ34 mL, end-systolic volume 78Ϯ23 mL; autografts: end-diastolic volume 157Ϯ33 mL, end-systolic volume 89Ϯ25 mL; PϭNS), whereas stroke volumes were maintained in both groups (homografts 67Ϯ15 mL, autografts 67Ϯ16 mL; PϭNS). RV SE was depressed in both groups to a similar degree to that seen with the previous group (homografts 1.5Ϯ0.3 cm, autografts 1.4Ϯ0.2 cm). Conclusions-Aortic valve replacement with either a pulmonary autograft or an aortic homograft leads to a degree of persistent RV longitudinal dysfunction that is not more pronounced in those undergoing the Ross procedure. The mechanisms and long-term effects of these changes must be further studied. (Circulation. 1999;100[suppl II]:II-36-II-41.

We used a sensitive assay to measure thrombin potential in 20 patients who underwent cardiopulmonary bypass surgery for coronary artery bypass grafts. We measured coagulation factors II, V, VII, VIII and X. Blood loss was measured as the total amount in the mediastinal drains in the first 24 h postoperatively. Thrombin potential was median 107 nmol/l.min (range 62-181) preoperatively and median 46 nmol/l.min (range 19-120) postoperatively. Coagulation factors II, V, VII,VIII and X were within normal limits preoperatively. Factor II fell from 77 IU/dl preoperatively to 37 IU/dl at 120 min postoperatively. Factor V fell from 85 IU/dl preoperatively to 61 IU/dl postoperatively. Factor VII fell from 91 IU/dl to 66 IU/dl postoperatively. Factor VIII was 128 IU/dl preoperatively and 127 IU/dl postoperatively. Factor X fell from 90 IU/dl preoperatively to 50 IU/dl postoperatively. Total blood loss in 24 h in the mediastinal drains postoperatively was mean 673 ml, median 650 ml (range 250-2000). Reduction in thrombin potential correlated inversely with postoperative blood loss, r= -0.75 (Spearman correlation). The fall in the thrombin potential correlated with the prothrombin level (r = 0.75) and factor X (r = 0.47).