Radial artery graft function is not affected by age

Radial artery as graft for coronary artery bypass surgery: Advantages and disadvantages for its usage focused on structural and biological characteristics

Radial artery (RA) is the most popular arterial graft after the left internal thoracic artery in both low- and high-risk patients undergoing coronary artery bypass grafting. Various arterial grafts such as the right internal thoracic artery, the right gastroepiploic artery, and the inferior epigastric artery have also gained ground over the past 30 years because of the intimal hyperplasia and atherosclerosis of the saphenous vein leading to late graft occlusion. In this review article we would like to present the utility of the RA as a graft, focused mainly on its structural and biological characteristics.

Late effects of radial artery versus saphenous vein grafting in patients aged 70 years or older

BACKGROUND

We aimed to determine whether the reported late survival benefit of radial artery (RA) versus saphenous vein (SV) grafting in the general coronary artery bypass graft surgery (CABG) population is maintained in elderly patients aged 70 years or older.

METHODS

We reviewed our 1996 to 2007 experience in 2,120 elderly patients (RA, n = 607; SV, n = 1,513) who underwent primary, nonsalvage CABG with multiple completed grafts including at least one internal thoracic artery (ITA) graft. Patients were excluded in case of single-vessel disease, bilateral ITA, ITA-only grafts, or concomitant valve/aortic surgery. Kaplan-Meier 12-year survival estimates were compared for 1-to-1 matched ITA/RA and ITA/SV cohorts based on a nonparsimonious RA use propensity model (48 variables).

RESULTS

The ITA/RA and ITA/SV cohorts (both, aged 75 ± 4yrs and 3.5 ± 0.8 grafts) were well matched and had identical operative mortality (2.3%; 11 of 480 each). Late survival was superior ITA/RA versus ITA/SV (p < 0.001), estimated at 85.1% versus 70.6% and 70.9% versus 50.5% for 5 and 10 years, respectively. Late survival risk ratios (95% confidence interval) for RA versus SV grafting was 0.47 (0.36 to 0.61), and the relative SV to RA death hazard was greater than 1 between 1 and 144 months.

CONCLUSIONS

The late survival results suggest that elderly (≥70 years) primary multivessel CABG patients benefit substantially when RA is used as the second conduit in combination with ITA. Indeed, compared with previously published comparisons including all age groups, the derived risk ratio indicates that the benefit for the elderly may exceed that for younger patients in the initial decade after CABG. Use of RA should not be avoided in the elderly.

Intra-aortic balloon pumping recruits graft flow reserve by lowering coronary resistances

BACKGROUND

The intra-aortic balloon pump (IABP) is used worldwide as an anti-ischemic strategy and to reduce myocardial workload. However, whether IABP augments coronary flow after coronary bypass via a passive increase in diastolic pressure or an active response of the coronary bed remains uncertain.

METHODS

We analyzed transit-time flow measurements and the contemporary changes in coronary resistances obtained during 1:1 IABP and during its cessation in 144 consecutive patients receiving prophylactic IABP before isolated coronary artery bypass grafting (n=340 graft segments).

RESULTS

Normally functioning grafts showed lower coronary resistances, greater percentage decrease in resistance, and greater increases in average maximum diastolic and mean flow during 1:1 IABP compared with IABP cessation (P<.001). Arterial and sequential saphenous vein grafts showed better flowmetry and greater reductions in coronary resistances compared with single venous grafts. Accordingly, graft flow reserve (defined as mean flow during 1:1 IABP/mean flow with IABP off) was recruited (graft flow reserve >1) during 1:1 IABP in all normally functioning grafts, with higher values in single arterial or sequential saphenous vein grafts than in single venous grafts (both P<.001). Coronary resistances were higher in 7 failed grafts versus normal-functioning grafts at baseline; these did not decrease during 1:1 IABP and showed worse transit-time flow results.

CONCLUSIONS

IABP recruits graft flow reserve by lowering coronary resistance in functioning grafts. Arterial and sequential venous grafts showed greater reduction in coronary resistance compared with single saphenous grafts.

Radial artery graft flowmetry is better than saphenous vein on postero-lateral wall

BACKGROUND

Although general agreement exists on internal mammary graft as the first conduit, the second choice is still questioned. Despite radial artery (RA) grafting has been suggested, saphenous veins (SV) continue to be extensively used.

METHODS

A prospective series of isolated RA-CABG (150 patients) or SV-CABG (180 patients), performed either off-pump (OP-CABG) and on-pump (CPB-CABG), in diabetics and non-diabetics, in elderly and young patients, during the last 5-years at a single institution were evaluated. RA was harvested with harmonic scalpel, flowmetry was performed with a transit-time flowmeter (TTF). Graft flow reserve (GFR) was calculated with intra-aortic balloon-pump. Follow-up was collected by outpatient clinic database or by telephone interview with general practitioners.

RESULTS

The 2 groups showed comparable preoperative and intraoperative variables. Mortality, morbidity, myocardial infarction, troponin I leakage, and echocardiographic parameters were comparable (p=NS). RA-CABG demonstrated significantly higher TTF maximum, mean and minimum flow (p<.001) with lower Pulsatility Index (p<.001), either in the circumflex and the right coronaries. Compared to SVG-grafting, significantly higher GFR was found in RA-CABG on the circumflex (p=.001) and right (p=.028) coronaries. 38.1+/-0.9 SE months follow-up resulted in higher survival and freedom from cardiac events in RA-CABG. Better TTF and GFR were demonstrated in OP-CABG, CPB-CABG, diabetics, non-diabetics, either on the circumflex and right coronary systems (p<.05). Better mean flow was detected in RA-CABG on the circumflex in the elderly (p=.04) and the young (p=.05).

CONCLUSIONS

RA-CABG demonstrated better TTF and GFR results compared to SV-CABG. These data may contribute to explain the survival benefit of arterial revascularization already reported.