L-Arginine and recovery after cardiovascular surgery

As the core substrate for nitric oxide (NO) synthesis, L-arginine plays key roles in vascular function repair, myocardial protection, microcirculation improvement, and inflammation regulation during recovery after cardiovascular surgery. It can help alleviate damage to the cardiovascular system caused by surgical trauma and accelerate patients’ postoperative rehabilitation process. The specific mechanisms of action and application essentials are as follows:

I. Core Mechanisms of Action

1. Dilating Blood Vessels to Improve Myocardial Perfusion and Microcirculation

Cardiovascular surgeries (e.g., coronary artery bypass grafting, heart valve replacement, stent implantation) can cause certain damage to vascular endothelium, leading to postoperative vascular endothelial dysfunction and insufficient NO synthesis, which in turn trigger vasospasm and myocardial ischemia. By supplementing the substrate for NO synthesis, L-arginine activates nitric oxide synthase (NOS) activity and promotes NO release from vascular endothelium. On the one hand, it dilates coronary and peripheral blood vessels, reduces vascular resistance, enhances myocardial blood and oxygen supply capacity, and alleviates postoperative myocardial ischemia symptoms. On the other hand, it improves microcirculation in tissues such as limbs and lungs, reduces the risk of postoperative thrombosis, and lowers the incidence of complications like pulmonary embolism and lower extremity venous thrombosis.

2. Protecting Myocardial Cells and Alleviating Ischemia-Reperfusion Injury

Transient myocardial ischemia and subsequent reperfusion during surgery generate a large amount of reactive oxygen species (ROS), causing oxidative stress damage to myocardial cells and impairing myocardial contractile function. NO produced from L-arginine can scavenge some ROS, mitigating oxidative stress-induced damage to myocardial cell membranes. Meanwhile, NO inhibits myocardial cell apoptosis signaling pathways, reduces myocardial cell death caused by ischemia-reperfusion, maintains the structural integrity of the myocardium, and supports the rapid recovery of cardiac function after surgery. Clinical studies have shown that postoperative L-arginine supplementation can increase patients’ left ventricular ejection fraction (LVEF) by 5%–10% and shorten the recovery time of cardiac function.

3. Regulating Postoperative Inflammatory Responses and Reducing Tissue Damage

Cardiovascular surgery is an invasive procedure that triggers the body’s inflammatory stress response. Excessive pro-inflammatory factors (e.g., TNF-α, IL-6) can exacerbate inflammatory damage to vascular endothelium and myocardium, delaying healing. Through NO-mediated anti-inflammatory pathways, L-arginine inhibits the infiltration of inflammatory cells into damaged sites and reduces pro-inflammatory factor levels. It also promotes the secretion of anti-inflammatory factors (e.g., IL-10), balances the postoperative inflammatory microenvironment, and reduces the risk of inflammation-mediated myocardial fibrosis and vascular stenosis. In particular, it exerts a certain inhibitory effect on vascular intimal hyperplasia after stent implantation.

4. Improving Lipid Metabolism and Reducing the Risk of Postoperative Atherosclerosis Recurrence

Most patients undergoing cardiovascular surgery have underlying atherosclerosis, and postoperative dyslipidemia is a major contributor to vascular restenosis. L-arginine can help regulate lipid metabolism, decrease blood levels of total cholesterol, triglycerides, and low-density lipoprotein cholesterol (LDL-C), increase high-density lipoprotein cholesterol (HDL-C) levels, and reduce lipid deposition on vascular walls. Long-term supplementation helps lower the recurrence rate of postoperative atherosclerosis.

II. Postoperative Application Essentials

1. Supplementation Timing and Dosage

Timing: It is recommended to start supplementation after patients’ vital signs stabilize and they can resume normal eating or receive enteral nutrition support, usually 24–72 hours postoperatively. For patients with severe preoperative vascular endothelial dysfunction, prophylactic supplementation can be initiated 1–2 weeks in advance under the guidance of a physician.

Dosage: The recommended oral daily dosage during postoperative recovery is 3–6 g, administered in 2–3 divided doses. For critically ill patients, short-term intravenous infusion (5–10 g per day) can be used under physician monitoring; high-dose self-supplementation should be avoided.

2. Safety and Contraindications

Indicated Populations: Suitable for postoperative patients undergoing coronary artery bypass grafting, stent implantation, heart valve replacement, etc., especially those with concurrent vasospasm or microcirculation disorders.

Contraindicated Populations: Prohibited for patients with severe hepatic or renal insufficiency (prone to hyperammonemia), those with postoperative bleeding tendency (NO may enhance anticoagulant effects), and individuals allergic to L-arginine. Patients taking anticoagulant drugs such as warfarin and aspirin need dosage adjustments under physician guidance to avoid increased bleeding risk.

Adverse Reactions: Excessive supplementation may cause gastrointestinal discomfort (nausea, diarrhea), headache, and hypotension, which can be quickly relieved by reducing the dosage.

3. Synergistic Interventions to Enhance Efficacy

Combining L-arginine with the following substances can improve postoperative recovery outcomes:

Synergizing with L-carnitine to further enhance myocardial energy metabolism and cardiac function.

Combining with antioxidants such as vitamin C and vitamin E to strengthen ROS-scavenging capacity and reduce oxidative stress damage.

Integrating with moderate postoperative rehabilitation exercises (e.g., bedside activities, slow walking) to more effectively improve vascular elasticity and myocardial function.

Through promoting NO synthesis, L-arginine supports postoperative recovery of cardiovascular surgery patients through multiple dimensions including vascular repair, myocardial protection, inflammation regulation, and lipid metabolism improvement. It can effectively reduce complication risks and shorten the rehabilitation cycle. However, its application must strictly follow the principles of individualized dosage, physician guidance, and contraindication avoidance, and be rationally used in conjunction with patients’ underlying diseases and postoperative physical conditions to maximize its clinical value.