The acronym CAB in medicine has two distinct and important meanings, depending entirely on the clinical setting. This three-letter abbreviation is used both for a complex heart procedure in the operating room and for a life-saving sequence in emergency situations. Understanding the context—cardiology or resuscitation—is necessary to correctly interpret what CAB refers to. This article explores the two most common uses of this acronym.
The Primary Definition: Coronary Artery Bypass
In the context of heart disease and surgery, CAB is an abbreviation for Coronary Artery Bypass, often shortened from the full procedure, Coronary Artery Bypass Grafting (CABG). This major operation restores blood flow to the heart muscle when the coronary arteries become narrowed or blocked by plaque buildup, known as coronary artery disease. The procedure creates a new pathway for blood to travel around a blockage, similar to a road detour.
The goal of this surgical intervention is to alleviate symptoms like angina (chest pain) and reduce the risk of a heart attack by improving oxygen supply to the heart muscle. To achieve this rerouting, a healthy blood vessel is taken from another part of the body and used to bridge the blocked section. This transplanted vessel is called a graft, which accounts for the “G” in the full acronym, CABG.
The graft is sewn onto the blocked artery below the obstruction and connected to the aorta or another major vessel above the blockage. Blood then flows through the new graft, bypassing the diseased segment and delivering oxygen-rich blood to the heart tissue. The success of the procedure depends on the patency (openness) of these new vascular connections.
Indications and Surgical Mechanics
Coronary Artery Bypass Grafting is typically required for severe coronary artery disease that cannot be managed with medication or less invasive procedures like stenting. Specific indications include blockages in the left main coronary artery or multi-vessel disease involving significant narrowing in two or three major coronary arteries. The procedure may also be necessary if a prior percutaneous coronary intervention (PCI) has failed.
Graft vessels are harvested from various parts of the body during surgery. The most durable choice is the internal mammary artery from the chest wall, which remains attached near the collarbone. Other common sources include the radial artery from the forearm or the saphenous vein from the leg. The surgeon determines the choice of vessel based on the number of bypasses needed and the patient’s overall health.
The surgical team usually gains access to the heart through a median sternotomy, which involves cutting through the breastbone. The procedure can be performed in two ways: “on-pump” or “off-pump.” On-pump surgery, the traditional approach, involves temporarily stopping the heart and diverting blood circulation to a heart-lung machine, allowing the surgeon to work on a still field.
The alternative, off-pump CABG, is known as “beating heart surgery,” where the heart continues to pump throughout the procedure. A stabilizing device immobilizes the small area where the graft is sewn. Off-pump surgery is often preferred for patients at higher risk of complications associated with the heart-lung machine, such as those with kidney issues or advanced age.
The Alternative Meaning: Circulation, Airway, Breathing
In emergency medicine and life support, CAB refers to the recommended sequence of steps in Cardiopulmonary Resuscitation (CPR). In this context, CAB stands for Circulation (Compressions), Airway, and Breathing. This sequence is a departure from the older ABC protocol, which began by checking the Airway first.
Modern guidelines, adopted by organizations like the American Heart Association, prioritize starting chest compressions immediately. The rationale is that the victim’s blood contains enough oxygen initially, but it must be circulated quickly to the brain and vital organs. Beginning with compressions minimizes the delay in restoring blood flow, which is crucial for survival and neurological outcomes.
The C-A-B order ensures the rescuer focuses on pushing hard and fast on the chest to maintain artificial circulation before pausing for rescue breaths. This change simplifies the initial response for lay rescuers, reducing hesitation. Starting with compressions minimizes the delay in receiving breaths, allowing for continuous, high-quality chest compressions.
Recovery and Long-Term Management Following Bypass Surgery
Following Coronary Artery Bypass Grafting, the patient is transferred to the Intensive Care Unit (ICU) for close monitoring of vital signs and heart rhythm for the first day or two. The total hospital stay is typically around one week, during which pain management is addressed, and the patient is mobilized with physical therapists. Full recovery from the sternotomy and the operation generally takes six to twelve weeks.
Long-term recovery relies heavily on cardiac rehabilitation, a structured program often beginning within a few weeks of discharge. This program incorporates medically supervised exercise, nutritional counseling, and education on heart-healthy living. Participation helps patients regain physical fitness and reduces the risk of future cardiac events.
Medication management is a permanent part of the post-CABG regimen to maintain graft health and prevent further disease progression. Patients are typically prescribed antiplatelet agents, such as aspirin, indefinitely to prevent blood clots in the new grafts. Statin medications are also used to manage cholesterol levels aggressively, slowing the buildup of plaque in the native coronary arteries and the grafts.
Necessary lifestyle changes, including adopting a heart-healthy diet, regular physical activity, and stopping smoking, are paramount for long-term success. Grafts from the internal mammary artery have an excellent chance of remaining open for ten years or more, though vein grafts are more susceptible to narrowing over time. Adhering to these medical and lifestyle protocols significantly increases the longevity of the bypasses and improves the patient’s quality of life.