Brief reports

Direct assessment of palmar circulation before transradial coronary intervention by color doppler ultrasonography

The frequency of radial artery occlusion was compared between patients receiving 4Fr versus 6Fr transradial coronary interventions (TRIs) in an open-label randomized trial (ClinicalTrials.gov identifier: NCT00815997). The primary outcome measure was radial artery occlusion on the day after TRI. The secondary outcome measures were the procedural success, major advanced cardiac events, access site–related complications, procedural times, fluoroscopy times, and contrast dye usage. A total of 160 patients were included. The procedure was successful in 79 of 80 patients (99%) in both groups. Whereas the 4Fr group showed no access site–related complications, the 6Fr developed 5 (6%), including 3 radial artery occlusions and 2 bleedings (1 radial artery perforation and 1 massive hematoma; p = 0.02). Although the radial artery occlusion rate was lower in the 4Fr versus the 6Fr groups, the difference was not significant (0% vs 4%, p = 0.08). The mean hemostasis time was significantly shorter in the 4Fr than in the 6Fr groups (237 ± 105 vs 320 ± 238 minutes, p = 0.007). In conclusion, these findings suggest that 4Fr TRI may become a less invasive alternative to 6Fr TRI in treating coronary artery diseases.

The development of ischaemia in the hand after harvest of a radial forearm flap is extremely rare. Previous cases have been caused by anatomical anomalies or conditions that may have been detectable by ultrasonography. We report the development of ischaemia after harvest of a radial forearm flap despite a normal preoperative Allen's test and a normal Doppler ultrasound scan, in a non-smoker with no evidence of peripheral vascular disease.

Angiographic appearances suggested that the ischaemia may have been secondary to an incomplete superficial palmar arch. This case highlights the potential for development of ischaemia despite normal preoperative investigations, with obvious ramifications for obtaining consent.

The purpose of this study was to assess the accuracy of the Allen’s test (AT) in predicting hand ischemia in patients undergoing transradial coronary angiography.

Patients with poor vascular communications between the radial artery (RA) and ulnar artery (UA), as indicated by an abnormal AT, are usually excluded from transradial coronary angiography to avoid ischemic hand complications.

Over a four-month period, patients undergoing coronary angiography were screened for AT time. Circulation in the RA, UA, principal artery of the thumb (PAT), and thumb capillary lactate were measured before and after 30 min of RA occlusion.

Fifty-five patients were studied (20 normal, 15 intermediate, 20 abnormal). Three patients with an abnormal AT were excluded, owing to absence of detectible flow in the distal UA. Patients with an abnormal AT were all men, had a larger RA (3.4 vs. 2.8 mm; p <0.001), and smaller UA (1.9 vs. 2.5 mm; p <0.001), compared with patients with a normal AT. After 30 min of RA occlusion in patients with abnormal AT, blood flow to the PAT improved (3.2 to 7.7 cm/s; p <0.001) yet remained reduced relative to patients with normal AT (7.7 vs. 21.4 cm/s; p <0.001. Thumb capillary lactate was elevated in patients with an abnormal AT (2.0 vs. 1.5 mmol/l; p = 0.019).

After 30 min of RA occlusion, patients with an abnormal AT showed significantly reduced blood flow to the thumb and increased thumb capillary lactate (compared with patients with a normal AT) suggestive of ischemia. Transradial cardiac catheterization should not be performed in patients with an abnormal AT.

Objective: Although the Allen test is crude and subjective, an objective color Doppler method has yet to be established in the assessment of hand circulation before radial artery harvesting. Doppler studies so far have neglected the Doppler principle that the insonation angles should be less than 30° and have not been compared with any standard except the crude Allen test. We therefore introduced the snuffbox technique, measuring the radial artery at the anatomic snuffbox, which is the most distal area after harvesting. Color Doppler methods were compared with the stump pressure as a criterion standard. Methods: Maximal flow velocity and Doppler angles of the snuffbox, palmar artery, and ulnar artery were measured in 20 hands before and after radial artery harvesting. Stump pressure was measured during surgery. Results: Maximal flow velocity in the snuffbox decreased with radial artery compression and after radial artery harvesting. All the flow patterns in the snuffbox technique showed simultaneous reversal. Maximal flow velocity in the ulnar artery increased with radial artery compression and after radial artery harvesting. Maximal flow velocity in the palmar artery did not change significantly with radial artery compression or after radial artery harvesting. Doppler angles were 20.9° ± 6.0° in the radial artery of the snuffbox, 82.5° ± 6.1° at the palmar artery, and 81.0° ± 7.6° at the ulnar artery. The changes in the snuffbox technique were highly correlated with the stump pressure ratio (P <.001). Conclusions: Among various color Doppler methods, the snuffbox technique was precise and reliable.

J Thorac Cardiovasc Surg 2003;125:821-5

Allen’s test (AT) and Modified Allen’s Test (MAT) are used as screening methods for assessment of the hand circulation. Few people lack the dual blood supply of hand and are at risk of hand ischemia after any intervention on radial artery. The Purpose of the study was to assess the collateral circulation of hand using MAT in normal Indian subjects and in elderly population to know the prevalence of positivity of Allen’s test.

900 participants (1800 hands) were divided in two groups. Group I had participants with age <50 years and group II had participants with age ≥50 years. MAT was performed in all participants and results were compared between the two groups.

In group I (n = 450, 900 hands), 313 were males and 137 were females, with mean age of 35.04 years. The relative percentages of a normal, equivocal, borderline and abnormal MAT were 77.8%, 16.6%, 3.7% and 1.6%, respectively. In group II (n = 450, 900 hands), 248 were males and 202 were females, with mean age of 60.4 years. The relative percentages of a normal, equivocal, borderline and abnormal MAT were 69.0%, 18.6%, 6.60% and 5.66%, respectively. A positive/abnormal test was significantly more common (5.66% Vs 1.66%, P < 0.00001) in older group.

MAT is simple, time tested and non invasive test to assess collateral circulation of the hand. A negative MAT safely selects patients for radial artery harvest; however, if the test is positive and in older patients then a second objective test may be needed.

Consistent anatomic accessibility, ease of cannulation, and a low rate of complications have made the radial artery the preferred site for arterial cannulation. Radial artery catheterization is a relatively safe procedure with an incidence of permanent ischemic complications of 0.09%. Although its anatomy in the forearm and the hand is variable, adequate collateral flow in the event of radial artery thrombosis is present in most patients. Harvesting of the radial artery as a conduit for coronary artery bypass grafting, advances in plastic and reconstructive surgery of the hand, and its use as an entry site for cardiac catheterization has provided new insight into the collateral blood flow to the hand and the impact of radial arterial instrumentation. The Modified Allen's Test has been the most frequently used method to clinically assess adequacy of ulnar artery collateral flow despite the lack of evidence that it can predict ischemic complications in the setting of radial artery occlusion. Doppler ultrasound can be used to evaluate collateral hand perfusion in an effort to stratify risk of potential ischemic injury from cannulation. Limited research has demonstrated a beneficial effect of heparinized flush solutions on arterial catheter patency but only in patients with prolonged monitoring (>24 h). Conservative management may be equally as effective as surgical intervention in treating ischemic complications resulting from radial artery cannulation. Limited clinical experience with the ultrasound-guided arterial cannulation method suggests that this technique is associated with increased success of cannulation with fewer attempts. Whether use of the latter technique is associated with a decrease in complications has not yet been verified in prospective studies. Research is needed to assess the safety of using the ulnar artery as an alternative to radial artery cannulation because the proximity and attachments of the ulnar artery to the ulnar nerve may potentially expose it to a higher risk of injury.