Continuing Education Activity

Radial artery coronary bypass is a surgical procedure utilizing the radial artery as a conduit for coronary artery bypass grafting (CABG). The radial artery is preferred after the left internal mammary artery, as it is easier to harvest and has better long-term patency rates than saphenous vein grafts (SVGs). SVGs are associated with shorter overall life spans and an increased risk of degeneration and occlusion following ischemic events. The muscular structure of the radial artery, akin to the internal mammary artery, and adaptability to high arterial pressure enhance its durability. This procedure improves survival rates and reduces complications, making it a valuable option for coronary artery bypass surgery patients.

Minimally invasive techniques, such as the "no-touch technique" and harvesting the graft as a pedicle, are being developed to improve outcomes further. This activity reviews the utility of the radial artery in CABG and provides clinicians with comprehensive knowledge about the indications, techniques, and benefits of using the radial artery in CABG. This activity covers detailed procedural steps from preoperative assessment to postoperative care, including managing potential complications and optimizing long-term outcomes. In addition, this activity enhances clinicians' understanding of interprofessional collaboration, patient-centered care strategies, and effective communication within the healthcare team, ultimately improving patient safety, outcomes, and overall team performance in radial artery coronary bypass procedures.

Objectives:

• Identify appropriate candidates for radial artery coronary bypass based on clinical indications and patient-specific factors.

• Assess and manage intraoperative complications related to radial artery grafting, ensuring immediate and appropriate interventions.

• Select optimal pharmacological therapies, including antiplatelet and anticoagulant regimens, to maintain radial artery graft function and prevent thrombotic events.

• Collaborate with interdisciplinary healthcare team members, including surgeons, anesthesiologists, and nurses, to ensure coordinated care throughout the perioperative period.

Introduction

Coronary artery bypass graft (CABG) surgery is the preferred treatment for severe left main and multivessel coronary artery disease, utilizing both arterial and venous graft combinations.[1][2] The left internal mammary artery remains the conduit of choice due to its superior long-term survival rates compared to other bypass conduits.[3] However, saphenous vein grafts (SVGs) are associated with shorter overall life spans and an increased risk of degeneration and occlusion following ischemic events. Within the first year after surgery, SVG occlusion rates range from 10% to 15%, escalating to 50% with significant or complete occlusion by 10 years.[4][5] Due to these concerns, alternative arterial conduits such as the right internal thoracic artery, right gastroepiploic artery, right inferior epigastric artery, and radial artery have been considered. Bilateral internal mammary grafts are generally avoided due to their association with higher sternal infection rates.[6] 

The radial artery graft has gained popularity as a preferred option after the left internal mammary artery due to its ease of harvest and ability to reach major coronary arteries. Carpentier et al first used the radial artery as an arterial conduit in 1973.[7] However, its use was abandoned within a few years because of the high occlusion rate. Acar et al reintroduced it in 1992 after discovering a patent radial graft on an angiogram performed in a patient 18 years after a CABG, which was previously considered occluded.[8] With improved surgical techniques and the utilization of antispasmodic agents, the radial artery graft patency rate has increased to more than 90% at 1 and 5 years after CABG.[9] 

Long-term clinical outcomes comparing the radial artery to the saphenous vein in CABG remain uncertain. Observational studies suggest potential postoperative benefits with the radial artery, although subject to bias. A pooled analysis by the Radial Artery Database International Alliance, using data from 5 randomized clinical trials, found significantly lower rates of death, myocardial infarction, or repeat revascularization at the 5-year follow-up with the radial artery compared to the saphenous vein.[10] 

Anatomy and Physiology

The brachial artery divides into the ulnar and radial arteries opposite the neck of the radius, with the radial artery being smaller in diameter. The radial artery travels backward along the lateral side of the carpus, passing under the tendons of the extensor pollicis longus and flexor pollicis longus toward the first and second metacarpal spaces. Upon reaching the palm, the radial artery crosses between the first and second dorsal interosseous muscles and forms a deep palmar arch with the superficial volar branch of the ulnar artery. In the forearm, it gives rise to the recurrent radial artery, and at the wrist, it supplies a volar carpal branch. In the hand, it branches into the superficial volar carpal branch.

Histologically, the radial artery's medial layer is predominantly muscular, rendering it prone to spasms. The muscular segments of both the radial artery and the internal mammary artery are similar.[11] The radial artery's adaptation to high arterial pressure, its diameter similar to coronary arteries, its suitable length for all coronary arteries, and its ease of harvesting without ambulation make it preferable to the SVGs in terms of morbidity and mortality.[12]

Indications

According to the joint 2021 American College of Cardiology (ACC)/American Heart Association (AHA) guideline, the radial artery is preferred over the saphenous vein as a conduit for surgical revascularization to bypass the second most critical target vessel with significant stenosis following the left anterior descending coronary artery. This preference is due to the radial artery's superior patency, reduced adverse cardiac events, and improved survival rates, making it a class I recommendation.[13]

Contraindications

Contraindications for using a radial artery graft during a CABG include:

• Abnormal Allen test
• Injury to the radial artery due to trauma or previous catheterization
• Dissection from prior arterial cannulation
• Significant radial artery stenosis on ultrasonography
• Arteriovenous fistula for hemodialysis
• Vasculitis [14]
• Raynaud disease [15]

Equipment

The equipment required for radial artery bypass graft include:

• Cardiopulmonary machine
• Surgical drape
• Sternal saw
• Clamps
• Retractors
• Forceps
• Scissors
• Needle holder
• Dilators and dissectors
• Suction cannula
• Sutures and needles
• Arterial cannula
• Venous cannula
• Cardioplegia cannula

Personnel

The personnel needed for radial artery bypass graft include:

• Cardiothoracic surgeon
• Cardiothoracic surgery assistant
• Anesthesiologist
• Interventional cardiologist
• Scrub technician
• Anesthesia technician
• Perfusionist for cardiopulmonary bypass machine
• Operating room nurse

Preparation

Preparation for a CABG using the radial artery involves the following steps:

• Essential routine tests include a complete blood count, creatinine, electrolytes, coagulation profile, liver function tests, electrocardiogram, and echocardiogram.

• Blood products, such as packed cell units, fresh frozen plasma, and platelets, should be arranged before the procedure.

• Patients should start fasting 6 hours before surgery.

• Continuing aspirin is crucial, particularly for those with acute coronary syndrome. However, P2Y12 inhibitors such as ticagrelor and clopidogrel should be stopped 5 days before the procedure, and prasugrel should be stopped 7 days prior.[16] 

• Antidepressants should be considered before surgery to reduce anxiety.

• Radial arteries should be harvested from the nondominant arm. A modified Allen test, using pulse oximetry and plethysmography, is performed preoperatively to assess arterial flow in the hand. An Allen test result of less than 10 seconds is necessary for harvesting the radial artery.

• Premedication with vasodilators, such as calcium channel blockers and nitrates, is crucial to reduce radial artery graft spasm and ensure vasodilation.

Technique or Treatment

Minimally invasive techniques for harvesting the radial artery are being considered to improve cosmetic and clinical outcomes.[13][17] Currently, the 2 most important steps to prevent radial graft failure are using the “no-touch technique” and removing the graft as a pedicle that contains the radial artery, the surrounding veins, and fatty tissue.[18][14] 

The nondominant hand is prepared and draped for the procedure. An arm board is used to avoid traction on the arm during table height adjustments. A curvilinear incision is made from 1 fingerbreadth distal to the biceps tendon to 1 fingerbreadth proximal to the radial styloid crease.

Diathermy is used to separate the deep fascia tissues, avoiding injury to the lateral cutaneous nerve, which overlies the radial artery at the distal end of the incision. The deep fascia is then separated medially from the brachioradialis muscle, minimizing injury to the radial artery side branches. Once the brachioradialis muscle is retracted, the side branches become visible.

The neurovascular fascia under the brachioradialis muscle, covering the radial artery and surrounding veins, is then separated to facilitate the harvesting of the radial artery. Pedicle dissection begins at the middle of the forearm, where the artery crosses under the brachioradialis muscle, carefully lifting the artery from its muscular bed. After gentle upward traction on the vessel loop, the side branches are ligated using a harmonic scalpel.

After mobilizing the radial artery, the proximal and distal divisions are prepared. First, the distal division is performed by placing a 2-0 silk suture around the artery where the radial styloid combines with the radial pedicle, followed by ligation. The distal stump of the radial artery is palpated to ensure adequate ulnar artery collateral supply. The proximal division is then performed, with the artery ligated with a 2-0 silk suture and divided. A special buffer solution containing heparin and papaverine is used to flush the radial artery lumen before and after transection.[19] The artery is stored in this solution until the anastomosis procedure. 

Electrocautery is used to achieve hemostasis of the radial artery graft. Before wound closure, a hand examination is performed to confirm hemostasis and reduce the risk of postoperative compartment syndrome. The wound is closed before administering systemic heparin, with the deep fascia sutured using a running 2-0 polyglycolic suture and the skin with a running 4-0 polyglycolic suture.

Complications

The following complications can occur after radial bypass graft surgery:

• Cutaneous paraesthesia secondary to damage to the lateral cutaneous nerve (most common)[20]
• Severe ischemia of the hand
• Graft site infection 
• Median and radial nerve injury [21]
• Radial artery spasm (more severe as compared to internal thoracic artery aneurysm)[22]
• Left ventricle dysfunction
• Stroke
• Acute renal injury
• Cardiac tamponade
• Pulmonary infection
• Cardiac arrhythmia

Clinical Significance

The radial artery graft is the second conduit option after the left internal mammary graft. Multiple studies have demonstrated superior patency rates and survival outcomes with radial artery grafts.[23][24]

Unlike the right internal thoracic artery, the radial artery is not associated with an increased risk of sternal wound infection. Additionally, unlike the right gastroepiploic artery and the inferior epigastric artery, the radial artery graft is suitable for use in obese patients and those with previous abdominal surgeries.[24]

Enhancing Healthcare Team Outcomes

Successfully managing radial artery coronary bypass surgery requires a cohesive interprofessional healthcare team comprising physicians, advanced practitioners, nurses, pharmacists, and other specialists. Physicians, including interventional cardiologists and cardiac surgeons, lead the team and are responsible for performing the procedure and overseeing patient care. Healthcare providers must collaborate closely with echocardiographers and radiologists who provide essential diagnostic imaging through echocardiograms and computed tomography scans. Advanced practitioners, such as nurses and physician assistants, play a critical role in preoperative assessment, intraoperative assistance, and postoperative follow-up.

Nurses are critical in care coordination, ensuring seamless continuity from preoperative preparation through postoperative recovery. They diligently monitor vital signs, administer medications, and educate patients on recovery and necessary lifestyle adjustments. In addition, pharmacists optimize medication management, particularly in dosing antiplatelet or anticoagulant therapies critical for maintaining graft patency and preventing complications.

The interprofessional healthcare team's collaboration and effective communication are crucial for enhancing patient outcomes and safety. This teamwork ensures all members are informed about the patient's condition and any procedural adjustments, fostering a collaborative environment that promotes patient-centered care. Such coordinated efforts guarantee patients receive comprehensive care, leading to superior surgical outcomes, reduced complications, and enhanced overall patient satisfaction.