Methods: After obtaining Faculty Ethics Committee approval and written informed consent from the patients, 72 adult patients (50 males, 27 females; mean age 62.9±9.3 years; range 37 to 75 years) who will undergo elective coronary artery bypass grafting (CABG) surgery were included in this study. We evaluated the vasodilatory effect of diltiazem alone (group 1), nifedipine alone (group 2), amlodipine alone (group 3), nebivolol alone (group 4) and nifedipine in combination with metoprolol (group 5). Seventy-seven patients who would undergo isolated CABG using radial artery were prospectively randomized to oral agents four or five days before operation. The dilatation of the lumen diameter and area of the radial artery were evaluated with high-resolution ultrasonography just before and 4-5 days after medical treatment.
Results: Diltiazem alone group (p=0.058) and niphedipine in combination with metoprolol group (p=0.067) did not show a significant increase in the lumen diameter and area after medical treatment compared to the pretreatment values. Statistically significant increases in lumen diameter and area were observed in nifedipine (p=0007), amlodipine (p=0.003) and nebivolol (p=0.047) groups.
Conclusion: Our results demonstrate that calcium channel antagonists are not equally effective in radial artery vasodilatation. Nifedipine, amlodipine and nebivolol appear to be the most effective agents in reducing radial artery spasm. Nebivolol is a betablocker and also has a potent vasodilatory effect on radial ar tery vasospasm.
The use of a potent vasodilator with minimal side effects is an important parameter for the successful use of the radial artery as a conduit in CABG surgery. We investigated and reported the vasodilatory effect of calcium antagonists and beta-blockers in this study.
Table 1: Patients demographics
Radial artery measurements
An ultrasound device (color Doppler Acuson 128 XP/10
with 7-MHz linear transducer, (Acuson, Mountain View,
CA, USA) was used for high-resolution ultrasound measurements
and color Doppler images. The measurements
of the radial artery lumen diameter were taken before
and after drug administration by a blinded evaluator. For
each patient, optimal radial artery images were obtained
between 2 and 5 cm above the radial styloid. This location
was marked, and all images were obtained at the
same location.
Statistical methods
All analyses were conducted with SPSS 10.0 software
(SPSS Inc, Chicago, Ilinois USA). Continuous variables
were presented as mean ± standard deviation; categorical variables were presented as numbers. Normality for
continued variables in groups was determined by the
Shapiro Wilk test. Because the variables did not show
normal distribution (p<0.05), comparisons of groups
were performed with the Kruskal-Wallis analysis of
variance test and pre-post comparisons with paired
observations were analyzed by using the Wilcoxon test.
The Fisher's exact test and Pearson Chi-square test
were used for comparison of discrete variables between
studied groups. In all statistical comparisons the p values
<0.05 were reported significant.
Table 2 summarizes the radial artery diameter before and after treatment (mm) and table 3 summarizes the radial artery cross-sectional area (mm2) before and after treatment. The respective mean pre-treatment and posttreatment RA diameter in each group follows: 3.5±0.7 and 3.6±0.6 mm in the diltiazem group (p=0.058); 3.3±0.7 and 3.6±0.7 mm in the nifedipine group (p=0.007); 3.6±0.6 and 4.0±0.6 mm in the amlodipine group (p=0.003); 4.2±0.8 and 4.5±0.7 mm in the nebivolol group (p=0.047) and 3.0±0.7 and 3.2±0.9 mm in the nifedipine + metaprolol group (p=0.067). The respective mean pre-treatment and post-treatment RA cross-sectional area in each group follows: 0.15±0.22 and 0.16±0.23 mm2 in the diltiazem group (p=0.05); 0.09±0.05 and 0.14±0.13 mm2 in the nifedipine group (p=0.004); 0.11±0.04 and 0.14±0.04 mm2 i n t he a mlodipine group (p=0.002); 0.14±0.06 and 0.17±0.05 mm2 in the nebivolol group (p=0.069) and 0.07±0.03 and 0.08±0.04 mm2 in the nifedipine + metaprolol group (p=0.103).
Table 2: Radial artery diameter before and after treatment (mm)
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