Abstract
Transradial cardiac catheterization and percutaneous coronary intervention are increasingly being performed worldwide in elective and emergency procedures, with many centers adopting the transradial route as their first choice of arterial access. One of the most common complications encountered during transradial procedures is radial artery spasm. This article reviews the current literature on the incidence, predisposing factors, preventive, and treatment measures for radial artery spasm.
1
Introduction
Transradial cardiac catheterization and percutaneous coronary intervention (PCI) are increasingly being performed worldwide in elective and emergency procedures , with many centers adopting the transradial route as their first choice of arterial access. Physicians and patients both favor the transradial route as it is associated with fewer bleeding and access complications, higher patient comfort level, earlier patient mobilization, and early discharge from hospital.
Radial artery spasm is one of the most common complications encountered by operators while performing transradial cardiac catheterization and PCI. It causes patient discomfort and reduces the procedural success rate. In this short review, we focus on four parts:
- 1.
The incidence of radial artery spasm during transradial cardiac catheterization
- 2.
The predisposing factors for radial artery spasm
- 3.
Discussion on management (prevention and treatment) of radial artery spasm
- 4.
Discussion on sedation and sheathless guiding catheters.
1.1
Radial artery spasm
Radial artery spasm can be defined as a temporary, sudden narrowing of the radial artery. It is usually diagnosed clinically and angiographically during cardiac catheterization. Clinically, it is associated with pain in the forearm which is aggravated by movement of the catheter/sheath, and there is difficulty in manipulating the catheter. There are also loss of radial pulse and damping of radial arterial pressure. Radial arteriogram ( Fig. 1 ) is usually obtained to confirm spasm and also to exclude vessel trauma. Angiographic confirmation is important as sometimes pain in the arm may not be caused by spasm but by other factors like tortuosity/loops in radial, brachial, or subclavian arteries which make the catheter movement difficult and cause pain to the patient. Quantification of radial artery spasm is also possible by using an automatic pullback device, although its practical use in the management of spasm remains undefined.
1.2
Incidence
The reported incidence of radial artery spasm during transradial cardiac catheterization ranged from 4% to 20% in the literature. The big range in the rate of incidence could be accounted partly by different types of intraarterial vasodilatory cocktails used in different cardiac catheterization laboratories. There is currently no definitive standard protocol for the optimal vasodilatory cocktail to be administered after successful insertion of the radial sheath.
Most vasodilatory cocktails will incorporate nitroglycerin on top of intraarterial heparin. Others may include verapamil and less commonly used agents like nitroprusside, nicorandil, diltiazem, lidocaine, molsidomine, magnesium sulphate, phentolamine, etc.
1.3
Predisposing factors
The exact mechanism causing radial artery spasm is unclear. Several clinical and anatomical factors have been identified as predisposing an individual to develop radial artery spasm during transradial cardiac catheterization. This exhaustive list of factors includes smaller radial artery diameter, presence of fixed atherosclerotic lesions, entrance of guidewires into side branches (thus inducing spasm), vessel tortuosity, larger arterial sheath diameters, longer procedure duration, female sex, younger age, lower body mass index, diabetes mellitus, number of catheters used, volume of contrast medium used, and unsuccessful access at first attempt. Preprocedural radial flow-mediated dilation has also been shown to be a significant predictor of arterial spasm, and its measurement can be performed noninvasively before cardiac catheterization. The measurements obtained by duplex ultrasound can help one decide on the vascular access route, size of the sheaths/catheters, or the type of vasodilatory cocktail to be used.
1.4
Management of radial artery spasm
1.4.1
Prevention
Radial artery spasm can be prevented by using well-proven intraarterial vasodilatory cocktails. Most vasodilatory cocktails will incorporate nitroglycerin on top of intraarterial heparin, and its effectiveness in reducing the radial artery spasm has been reported by several studies .
Instead of the intraarterial route, nitroglycerin can also be given as a sublingual tablet or via administration of subcutaneous injection near the radial artery. Further evidence of the effectiveness of nitroglycerin comes from a surgical study which investigated the best topical vasodilator for preventing radial artery spasm during harvesting for coronary artery bypass grafting. The results of the study showed that topical application of nitroglycerin solution effectively prevented perioperative spasm of the radial artery.
Caution must be exercised when other agents are added to the vasodilatory cocktail. The addition of verapamil can potentially lead to hypotension, and its use is relatively contraindicated in patients with severe left ventricular dysfunction and bradycardia. In a head-to-head comparison study between two vasodilatory cocktails which included 3000 U of heparin and 100 µg of nitroglycerin±1.25 mg of verapamil, there was no statistically significant difference in the incidence of radial artery spasm.
Intraarterial cocktail that included heparin only is associated with a high incidence of radial artery spasm (as high as 20%). Heparin (50–100 U/kg) is usually administered as part of the radial cocktail to prevent radial artery thrombosis and is an irritant to small arteries. Rapid bolus injection through the radial sheath is associated with pain which could induce spasm. Some operators may opt to give heparin intravenously to minimize the occurrence of pain.
Another proven method to prevent radial artery spasm is to use a hydrophilic-coated radial sheath. Several studies have shown the effectiveness of these specially coated sheaths over uncoated sheaths in reducing the incidence of spasm. For the hydrophilic sheaths, no significant difference was observed between long and short sheaths.
Based on the current evidence, we recommend incorporating nitroglycerin (minimum dose of 100 µg) into the radial cocktail and using smaller-sized hydrophilic-coated sheaths/catheters as preventive measures for radial artery spasm. When heparin is part of the intraarterial cocktail, the cocktail should be administered slowly through the radial sheath to avoid inducing pain which could trigger arterial spasm. Operator experience can also play an important role in preventing radial artery spasm, as there will be higher chance of obtaining radial access by single stick and less manipulation of the catheter during the procedure.
1.4.2
Treatment
There are currently limited data on the optimal treatment measure for radial artery spasm. Based on our combined experiences of working in different cardiac catheterization laboratories, we make a few recommendations on the possible treatment measures. Radial artery spasm can occur in different degrees of severity and at any stage of the procedure. It can entrap the catheter or sheath, leading to pain during catheter manipulation or when removal is attempted. As mentioned earlier, it is important to obtain angiogram of the radial artery, whenever possible, to evaluate the spasm and exclude vessel trauma. For mild–moderate degrees of arterial spasm, one can inject intraarterial nitroglycerin or verapamil through the catheter or sheath to relieve the spasm. One can also give sublingual nitroglycerin to the affected patient. It is important to alleviate the patient’s pain and anxiety by using intravenous morphine, fentanyl, and midazolam. It is also extremely important to exercise great caution during steady pull-back of the sheath/catheter and to never forcefully pull the sheath/catheter out as this could lead to vessel trauma (dissection/perforation) necessitating surgical repair. The above steps maybe repeated until the arterial spasm is fully relieved with continuous monitoring of arterial blood pressure. Patience is essential to ensure smooth removal of catheter/sheath. In rare cases of severe radial spasm whereby the above measures do not work and the catheter remains entrapped, one should consider general anaesthesia as a last resort to resolve the problem. On the other hand, if the spasm is successfully relieved but the procedure is not completed, a smaller-caliber diagnostic or guiding catheter should be used if the operator wants to continue using the transradial route; otherwise, access site crossover to femoral artery would be necessary.
1.5
Sedation
It is important to bear in mind that the vascular tone of radial artery is susceptible to the body’s sympathetic tone besides clinical and anatomical factors. Radial artery spasm can be easily triggered by fear, anxiety, and pain, and conscious sedation maybe useful to alleviate all these factors so that the incidence of spasm can be reduced. In this regard, conscious sedation may potentially play a more important role in transradial cardiac catheterization than transfemoral cardiac catheterization. Currently, there is no evidence for routine use of conscious sedation in transradial cardiac catheterization, but it maybe useful for selected group of patients for prevention and treatment of radial artery spasm.
1.6
Sheathless guiding catheters
The development of Asahi sheathless hydrophilic guiding catheters (Asahi Intec Co., Ltd., Nagoya, Japan) has enabled operators to perform complex PCI transradially instead of using 7-Fr guiding catheter transfemorally. This catheter has hydrophilic coating along its entire length, making it advantageous for prevention of radial artery spasm. Some operators have also recommended the use of sheathless guiding catheters in patients who developed severe radial artery spasm during transradial procedures. Initial experiences with these new devices have been favorable, although one study did report a 5% incidence of radial artery spasm.
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