Radial catheterization complications

# Overview
Like any other arterial puncture in any part of the body, complications are not uncommon, including radial artery spasms and occlusion, bleeding, radiation exposure, e.t.c.  However, these complications can be minimized by the use of appropriate medications, radiation protective devices, and most importantly, by implementing efficient, high-quality, and personalized transradial training programs that educate the entire catheterization laboratory team.

# Complications

### Radial Artery Spasm
Radial artery spasm (RAS) remains one of the major limitations of transradial approach for PCI. The radial artery was demonstrated to have stronger contractions to common vasoactive substances, thus, increasing its propensity to spasm especially in situations of trauma. The incidence of RAS varies from 12% among high risk patients in whom transfemoral approach was contraindicated to 22% among patients without prior administration of intra-arterial vasodilators.  The increased incidence in RAS may be due to the small size of radial artery, female gender, long and difficult procedures with multiple catheter exchanges, sheath size, and operator inexperience.
Some of the measures that have been shown to reduce the incidence and severity of RAS include:
- Generous patient sedation
- Use of spasmolytic cocktails such as verapamil, nitroprusside or combination of both
- Use of a hydrophilic sheath of the smallest possible diameter
- Wiping and flushing catheters with solutions containing calcium channel blocker or nitrates
- Using a smaller catheter size
- Use of intra-arterial Papaverine for the treatment of severe arterial spasm
- Adequate time should be given for the artery to relax before removing catheters or sheaths to prevent arterial evulsion

### Radial Artery Occlusion
Although most cases of radial artery occlusion are asymptomatic, cases of hand ischemia have been reported.  As a result of this, coupled with the fact that a persistent RAO could make future access of the ipsilateral radial artery for angioplasty, intra-arterial pressure monitoring, coronary artery bypass surgery, or hemodialysis impossible or difficult, more aggressive measures should be implemented to prevent RAO, especially nowadays where greater than 50% of physicians performing transradial PCI do not routinely evaluate radial arterial patency before discharging their patients.
According to the Best Practices for Transradial Angiography and Intervention (2013), the evidence-base practices associated with a reduced risk of RAO include:
aUnfractionated heparin 70 units/Kg up to 5000 units and bivalirudin 0.75 mg/kg bolus followed by 1.75 mg/kg/hr infusion during procedure.  bThis is the most effective strategy to reduce the risk of RAO
Below are the steps involved in the patent hemostasis process:

### Hematoma
Varying degrees and severities of hematomas have been reported.  The most common location occurs at the puncture site, but rare cases involving the mediastinum, mediastinum and neck, or even the forearm muscle have been reported in association with the transradial approach.  A grading system similar to the femoral approach have also been used: Grade 1 (<5cm), grade 2 (<10cm), grade 3 (distal to the elbow) and grade 4 (proximal to the elbow).  The independent predictors of bleeding were identified as: creatinine clearance <60 mL/min, procedure duration, and sheath size.

### Compartment Syndrome
Bleeding is a common complication of r-PCI which can result into devastating consequences.  Compartment syndrome is a limb-threatening surgical emergency which requires a high index of suspicion and timely application of appropriate protocols once local bleeding is suspected such as discontinuation of anticoagulant therapy, pain and blood pressure control, external compression with a blood pressure cuff, close monitoring of distal perfusion of the hand (plethysmography) and consultation to a vascular surgeon is also recommended in cases of limb ischemia.

### Increased Exposure to Radiation
Some observational studies have shown that the transradial approach to PCI is associated with an increased radiation exposure in the patient, and especially, the operator.  According to a large study, radial artery catheterization was associated with a 23% increase in radiation exposure when compared with the transfemoral access.  This is largely dependent on operator proficiency.  Two studies demonstrated that increasing operator experience with the transradial approach is associated with a lower patient and operator radiation exposure.  Some measures which have been shown to reduce exposure to radiation include the use of transradial protection board, lead-free radiation shield over the right sheath insertion site, and the use of left radial artery, which is associated with a lower fluoroscopy time and radiation dose compared with the right radial angiography.
Other complications associated with the transradial approach are listed below:
- Local pain and swelling
- Thrombosis
- Embolization
- Infection
- Pseudoaneurysm
- Blood loss
- Limb ischemia
- Arteriovenous fistula
- Cerebral embolization
- Peripheral neuropathy
- Accelerated atherosclerosis
- Transient vocal cord paralysis
- Delayed reflex sympathetic dystrophy
- Subcutaneous granulomatous reaction (hydrophilic coating) or sheath-associated sterile abscesses
Optical coherence tomography (OCT) has been used by Yonetsu et al to define the damage to the radial artery in 73 arteries of 69 patients . 32% of patients developed intimal tears and 16% of patients developed medial dissections. Repeat catheterization was associated with increased fibro-intimal hyperplasia.  Cardiac catheterization via the radial approach may render the radial artery unsuitable for coronary artery bypass grafting.  There can be a loss of pulse in about 4% of cases.  Use of smaller guide catheters and sheathless guides may potentially reduce the risk of these complications.