Radial artery occlusion (RAO) (Fig. 5.3) is one of the most common complications in TRI with an incidence of 5–11% and is generally asymptomatic due to the dual blood supply of the hand [7–10]. Severe hand ischemia resulting from RAO is rare, except for the presence of some underlying pathology, such as defective palmar circulation and vascular dysfunction. Since simple pulse check at the radial artery is not reliable, ultrasound is recommended to assure the diagnosis. The occurrence of RAO has been found to be related to intimal hyperplasia, intima-media thickening, and thrombus formation mainly caused by artery injury and prolonged high-pressure compression. Although RAO usually requires no further treatment, measures should be taken to prevent it. Allen’s test is critically important for selecting patients with patent palmar arch communications. Currently, the use of heparin is a standard procedure in TRI and adequate anti-coagulation with heparin may reduce the incidence of RAO. Moreover, there are several commercially available radial compression devices with enough maintenance of perfusion during compression, which has been shown to decrease the rate of RAO [9–11]. Additionally, the use of a smaller size sheath or guide catheter may be potentially advantageous in the prevention of RAO. It’s worth noting that reaccessing the occluded radial artery is a concern for future TRI. Although different techniques have been reported to recanalize a previously occluded radial artery [12, 13], none of them have been universally accepted and approved for clinical practice. Occasionally, a branch of radial artery can be occluded due to TRI. A special case of acute princeps pollicis artery occlusion is provided (Fig. 5.4).

Radial artery perforation (RAP) is an uncommon complication (Fig. 5.5), which, if not identified promptly, can lead to severe forearm hematoma and compartment syndrome. The reported incidence of RAP is between 0.1 and 1% in different studies and it occurs more often in older and shorter women with tortuous arteries [14–16]. Risk factors of RAP have been related to artery spasm, small radial artery, excessive anti-coagulation, and over manipulation of guidewire. Generally, it is not easy to detect RAP during the procedure because of temporary tamponade provided by the catheter shaft. However, it can manifest as a forearm hematoma post-procedurally. Early detection of this complication can be achieved by angiography when the guidewire or catheter insertion meets resistance. If detected early, RAP can be treated simply with a pressure bandage; and if it progresses to a large hematoma to increase the risk of compartment syndrome, then surgical intervention is required. To carry on the procedure in patients with RAP, two strategies have been adopted: conversion to transfemoral approach or continuing the procedure either with the use of a long sheath, a guiding catheter, or a peripheral balloon to close the perforation [15, 17, 18]. A case of RAP is illustrated in Fig. 5.6.

Owing to the superficial location of the radial artery, hemostasis post-TRI can be achieved readily with a significant reduction of bleeding complications. However, this complication is not completely eliminated and it, if overlooked, can lead to forearm hematoma and even to compartment syndrome with disastrous outcomes. Hematoma is a subcutaneous collection of blood deriving from penetrating injury either on the vessel wall or its minor branches during the delivery of devices or from inadequate compression post-procedure. The factors associated with bleeding after TRI include renal dysfunction, procedure duration, sheath size, female gender, advanced age, multiple puncture attempts, and aggressive use of anti-coagulation. Forearm hematoma is probably the most common bleeding complication of TRI and is described as the forearm swelling and pain, increased skin temperature and tension, and local skin bruising or blisters. Nevertheless, the exact incidence of forearm hematoma is not known because minor bleeding has no clinical implications. Conversely, more severe hematomas are noticed when swelling and pain of the puncture site are present. Usually prolonged compression may be enough to manage hematoma after ultrasound is used to exclude major injury of the artery. Forearm hematoma is caused by bleeding from the puncture site into the tissues of the forearm. A hematoma classification with different treatment strategies has been proposed by Bertrand, with Grade I and II being related to puncture site and Grade III and IV related to intramuscular bleeding (Fig. 5.7) [19]. In addition, major bleeding complications are markedly reduced with transradial approach over transfemoral approach.

The forearm contains four inter-communicated compartments: superficial volar compartment, deep volar compartment, dorsal compartment, and Henry’s mobile wad compartment, each of which consists of bone, interosseous membrane, intermuscular septa, and aponeurotic fascia, forming a closed chamber with tough and inflexible structure (Fig. 5.8). When there is a sharp increase in pressure of the chamber, the normal capillary flow and lymphatic drainage within the forearm is impeded, which progressively results in muscular and nervous damage. Compartment syndrome is a extremely rare complication of TRI. Possible causes can be unrecognized perforation at a distance from the puncture site, unsuccessful compression at the access site, or radial artery laceration induced by sheath insertion or removal because of severe spasm [20]. Typical symptoms of compartment syndrome are described as 5 “P” signs: pain, pallor, paresthesia, paralysis, and pulselessness. If compartment syndrome is not immediately identified and appropriately managed, patients may suffer amputation, acute renal failure, and even death. Given the catastrophic consequences of this complication, prevention is of vital importance. First, it is mandatory to check the patency of the hand collateral arteries during and after procedure. Second, radial tortuosities and anatomical variations should be managed properly during the procedure. If there is a severe spasm with the removal of the sheath, an anti-spasmolytic therapy should be given. The compression device should be placed accurately and periodically reviewed after procedure. Third, bleeding complications should be identified and treated promptly. Fourth, every complaint of the patient about pain or swelling of the arm should be taken into account. Treatment measures include dehydration and decompression. If pressure elevation caused by small hematoma is mild or modest and patients do not experience severe symptoms, conservative treatment should be applied, such as proper compression to stop the bleeding, dehydration with mannitol or furosemide to reduce the pressure, and discontinuation of anti-coagulation. If there is no symptomatic relief or the swelling aggravates, a surgical consultation is needed to perform fasciotomy. A case of compartment syndrome is illustrated in Fig. 5.9.