Abstract
Background
Transradial access (TRA) offers advantages including decreased vascular complications, reduced length of hospital stay, and reduced cost. The size of the radial artery (RA) limits the equipment that can be used via TRA. Intra-arterial (IA) vasodilators prevent and treat RA spasm, yet are not uniformly used in TRA and their effect on the absolute size of the RA remains unknown.
Methods and materials
121 patients undergoing TRA for cardiac catheterization were included. 78 patients underwent RA angiography prior to administration of IA vasodilators (‘no vasodilator’ group), 43 patients underwent radial angiography after administration of an IA verapamil and nitroglycerin cocktail (‘vasodilator’ group). Quantitative angiography was used to compare the RA diameters.
Results
Clinical characteristics were similar between the groups, except that patients in the ‘no vasodilator’ cohort were taller (1.67 ± 0.1 m vs. 1.73 ± 0.1 m, p = 0.002), and heavier (84.9 ± 18.2 kg vs. 75 ± 17.1 kg, p = 0.003). In the ‘vasodilator’ group the proximal RA diameter was larger (2.29 ± 0.47 mm vs. 2.09 ± 0.41 mm, p = 0.02) as was the narrowest segment (1.83 ± 0.56 mm vs 1.39 ± 0.43, p < 0.0001) compared to the ‘no vasodilator’ group. At the RA origin, 79.4% of those in the ‘vasodilator’ group were larger than a 6 Fr guide catheter, compared to 51.4% in the ‘no vasodilator’ group (p = 0.004). At the narrowest segment a higher percentage of RAs in the ‘vasodilator’ group were larger than a 5 Fr guide catheter (65.1% vs 26.9%, p < 0.001) and a 6 Fr catheter (34.9% vs 10.3%, p = 0.001).
Conclusion
IA vasodilators increase pre-procedural RA diameter in patients undergoing cardiac catheterization via TRA. This increase in diameter has important implications for procedural planning.
Summary for Table of Contents
Boyer et al. performed a blinded controlled clinical trial investigating the effects of intra-arterial vasodilators on radial artery size and spasm during cardiac catheterization. The study demonstrates that intra-arterial vasodilators significantly increased the radial artery size throughout the entire course of the vessel and significantly decreased the amount of radial artery spasm. The authors conclude that these findings support the use of intra-arterial vasodilators during cardiac catheterization and have important implications for emerging technologies such as larger bore sheathless radial procedures.
1
Introduction
Transradial access (TRA) for cardiac catheterization is increasing in the United States and worldwide . Advantages of TRA include decreased bleeding, fewer vascular access site complications, reduced length of hospital stay, and utilization of fewer hospital resources when compared to transfemoral access (TFA) . One of the limitations of TRA, however, is the relatively small size of the radial artery and its propensity for spasm. Compared to the femoral artery, the smaller diameter of the radial artery can limit operators to smaller catheter and sheath sizes, thereby limiting catheter-based therapies. Intra-procedural spasm can further prevent arterial access or prevent successful catheter manipulation often leading to procedural failure or conversion to TFA. Iatrogenic catheter or sheath injury to the endothelium in the setting of spasm, or smaller arterial diameter relative to sheath or guide catheter, may also contribute to radial artery occlusion, preventing future radial access. Thus, there is a need to maximize the size of the radial artery.
As increasingly more complex coronary interventions are performed through the radial artery, there will be a continued demand for pharmacologic and procedural strategies to avoid the aforementioned complications. One such strategy is the use of intra-arterial vasodilators delivered through an arterial sheath prior to coronary angiography. In this setting, vasodilators have been shown to reduce the incidence of radial artery spasm yet their use remains variable . Recent studies have shown that up to 14.1% of operators do not use any vasodilators . We therefore sought to characterize objectively the effects of intra-arterial vasodilators on radial artery diameter using quantitative angiography (QA). Further, we sought to explore the implications of the use of vasodilators in potentially facilitating the use of newer generation TRA devices, such as lower profile guides and sheathless guide systems, by comparing the radial artery diameters at the origin and point of maximal spasm to the external diameters of contemporary guide catheters and sheaths.
2
Methods
We compared two groups to assess the effects of intra-arterial vasodilators on radial artery size and spasm ( Fig. 1 ). The primary endpoint was the size of the radial artery measured by quantitative angiography at its origin and at the narrowest segment (point of maximal spasm) as determined by a blinded reviewer.
Indications for coronary angiography in both groups included new-onset angina or chest pain, acute coronary syndrome (ACS) including unstable angina or NSTEMI, or abnormal stress testing. All patients received moderate sedation with intravenous fentanyl and midazolam, as well as subcutaneous 1% lidocaine for local anesthesia prior to arteriotomy.
Arterial access was achieved using a 21 g, 1.5” (38 mm) metal needle, Spring straight .021 wire and a Glidesheath (Glidesheath, Terumo Medical Corp, Somerset, NJ). Operator experience was variable from first year cardiology fellow to attending interventional cardiologist.
The first group, or ‘no vasodilator’ group, was selected from the placebo arm of the Pre-Dilate study. The Pre-Dilate study was a randomized, placebo-controlled trial of topical nitroglycerin and lidocaine prior to radial artery access concomitantly performed in our cardiac catheterization laboratory .
After sheath insertion, patients in the ‘vasodilator’ group received 200 μg intra-arterial nitroglycerin and 200 μg of intra-arterial verapamil while those in the ‘no vasodilator’ group received no intra-arterial vasoactive medications. All patients received intravenous administration of 50–70 U/kg of unfractionated heparin. Radial angiography was then performed for all patients ( Fig. 2 ). After radial angiography, those patients in the ‘no vasodilator’ group then received 200 μg intra-arterial nitroglycerin and 200 μg of intra-arterial verapamil as per laboratory protocol for TRA cases. At the completion of the case, the radial sheath was removed and EZ band was applied to achieve hemostasis. Attempt was made to achieve patent hemostasis in all patients .
Inclusion criteria for the trial were: age greater than 18 years, adequate dual blood supply to the hand, and willingness to provide written informed consent in English. Exclusion criteria were inability to receive nitroglycerin, nicardipine, verapamil, or lidocaine due to allergy or medication interactions, vasculopathy, conditions that may impair vasodilation, chronic use of long-acting nitrates, and inability to sign consent in English. Patients with STEMI, shock, those requiring general anesthesia, or emergent procedures were also excluded.
Quantitative angiographic analysis of the radial artery segments was performed for each patient by a blinded reviewer. The boundaries of a selected radial artery segment were detected automatically from optically magnified image of a cineframe. The absolute diameter of the artery in mm was determined with the sheath as a scaling device. Calibration of the sheath as an absolute value (mm) was achieved by comparing the mean diameter of the sheath in pixels with the known size in millimeters. Each sheath was measured individually. For each patient, after calibration to the sheath size, we measured the diameter of the brachial and ulnar arteries, as well as the radial artery at its origin and at its narrowest point. We compared the size of the radial arteries with outer diameters (OD) of commercially available sheaths (Terumo Glidesheath) and guide catheters (Vista Brite-Tip, Cordis Corp) ( Table 3 ). The values were obtained from published information on manufacturers website and catheter or sheath package insert .
For statistical analysis, continuous variables were expressed as mean ± standard deviation and categorical variables as percentages. Between treatment groups, the unpaired Student’s T test was used for comparison of continuous variables, and the Pearson’s Chi-squared test for comparison of categorical variables. All computations were performed with STATA 10.0 and a p value < 0.05 was considered statistically significant for the testing of hypothesis.
2
Methods
We compared two groups to assess the effects of intra-arterial vasodilators on radial artery size and spasm ( Fig. 1 ). The primary endpoint was the size of the radial artery measured by quantitative angiography at its origin and at the narrowest segment (point of maximal spasm) as determined by a blinded reviewer.
Indications for coronary angiography in both groups included new-onset angina or chest pain, acute coronary syndrome (ACS) including unstable angina or NSTEMI, or abnormal stress testing. All patients received moderate sedation with intravenous fentanyl and midazolam, as well as subcutaneous 1% lidocaine for local anesthesia prior to arteriotomy.
Arterial access was achieved using a 21 g, 1.5” (38 mm) metal needle, Spring straight .021 wire and a Glidesheath (Glidesheath, Terumo Medical Corp, Somerset, NJ). Operator experience was variable from first year cardiology fellow to attending interventional cardiologist.
The first group, or ‘no vasodilator’ group, was selected from the placebo arm of the Pre-Dilate study. The Pre-Dilate study was a randomized, placebo-controlled trial of topical nitroglycerin and lidocaine prior to radial artery access concomitantly performed in our cardiac catheterization laboratory .
After sheath insertion, patients in the ‘vasodilator’ group received 200 μg intra-arterial nitroglycerin and 200 μg of intra-arterial verapamil while those in the ‘no vasodilator’ group received no intra-arterial vasoactive medications. All patients received intravenous administration of 50–70 U/kg of unfractionated heparin. Radial angiography was then performed for all patients ( Fig. 2 ). After radial angiography, those patients in the ‘no vasodilator’ group then received 200 μg intra-arterial nitroglycerin and 200 μg of intra-arterial verapamil as per laboratory protocol for TRA cases. At the completion of the case, the radial sheath was removed and EZ band was applied to achieve hemostasis. Attempt was made to achieve patent hemostasis in all patients .
