Pediatric Coronary Artery Bypass Surgery

Overview

Coronary artery bypass surgery, commonly known as coronary artery bypass graft (CABG) surgery and informally as heart bypass or bypass surgery, is a surgical operation used to restore normal blood flow to a clogged coronary artery. A healthy coronary artery carries blood directly to the heart muscle, not through the circulatory system.

Coronary bypass surgery bypasses blood around a section of your heart's blocked or partially blocked artery. A healthy blood artery from patient's leg, arm, or chest is taken and connected below and above the blocked arteries in the heart. Blood flow to the heart muscle improves with a new pathway.

The cardiac condition that caused the blockages, such as Kawasaki disease or congenital heart disease, is not cured by coronary bypass surgery. It can, however, alleviate symptoms such as chest discomfort and shortness of breath. This surgery can improve heart function and lower the chance of dying from heart disease in certain patients.

Pediatric coronary artery bypass surgery (PCABS) for congenital heart disease has become more significant in infants and children undergoing current cardiac surgical procedures because to its life-saving potential in failed coronary transfer operations.

Because compelling indications are uncommon, pediatric coronary artery bypass surgery (PCABS) for congenital heart disease (CHD) is performed infrequently. However, the introduction of more radical operations requiring a coronary transfer, such as the arterial switch operation (ASO) for complete transposition of the great arteries (TGA) and the aortic reimplantation procedure for anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA), has introduced new surgical complications. The significance of PCABS in neonates, babies, and children has increasingly grown because of the infrequent but critical immediate or late development of ischemic myocardial problems associated with coronary transfer procedure.

PCABS should be regarded distinct from bypass surgery for adults since individuals are developing fast, with a rising demand for exercise capacity, and graft patency is predicted to last more than 50 years.

How coronary artery bypass is one?

Presurgical evaluation:

• The doctor will describe the procedure and allow the parents to ask questions before asking them to sign a consent form granting permission to do the test. They should carefully study the form and ask questions if anything is confusing.
• Along with a review of the patient's medical history, the doctor will perform a full physical exam to ensure that the child is otherwise healthy before proceeding with the surgery. Blood testing and other diagnostic procedures may be carried out.
• Inform the doctor about all prescription and over-the-counter medications, vitamins, herbs, and supplements that the baby is taking.
• Inform the doctor if the child has a history of bleeding issues or is using any blood-thinning medications, aspirin, or other blood-clotting medications. Some of these medications may be discontinued prior to the operation.

Procedure:

A hospital stay is required for coronary artery bypass graft surgery (CABG). The procedure may differ based on the patient's health and the doctor's practices.

Generally, CABG follows this process:

1. During the surgery, the anesthesiologist will continually check the patient's heart rate, blood pressure, respiration, and blood oxygen level. Once the patient has been sedated (put to sleep), a breathing tube will be inserted into the patient's throat and the patient will be attached to a ventilator, which will breathe for the patient during the surgery.
2. A healthcare provider will place an intravenous (IV) line in the patient's arm or hand. Other catheters will be placed in the neck and wrist to monitor heart and blood pressure and to collect blood samples.
3. An antiseptic solution will be used to clean the skin above the surgery site.
4. After all of the tubes and monitors are in place, the doctor will make incisions (cuts) in one or both sides of the chest to gain access to the blood vessel(s) that will be utilized for the grafts. He or she will remove the vessel or vessels and seal the incisions (s).
5. The doctor will create an incision (cut) from the Adam's apple to just above the umbilicus.
6. The sternum (breastbone) will be sliced in half lengthwise by the doctor. He or she will split the breastbone halves and spread them apart to reveal the heart.

Coronary artery bypass graft surgery-on-pump procedure:

1. The doctor will need to momentarily stop your heart in order to stitch the grafts into the very narrow coronary arteries. A heart-lung bypass machine will be used to pump blood across the body via tubes placed in the heart.
2. After diverting the blood to the bypass machine for pumping, the doctor will stop the heart by injecting it with a cold solution.
3. After the heart has been stopped, the doctor will suture one end of a portion of artery or vein over a tiny opening made in the aorta and the other end over a tiny opening made in the coronary artery right below the obstruction to perform the bypass graft surgery.
4. Depending on the number of blockages and their location, the patient may require more than one bypass graft. After all of the grafts have been placed, the doctor will carefully examine them while blood flows through them to ensure that they are functioning properly.
5. Once the bypass grafts have been evaluated, the doctor will let the blood circulating through the bypass machine to return to the patient's heart and remove the machine's tubes. The heart may restart on its own or with the help of a small electric shock.
6. The doctor may insert temporary pacing wires into the heart. These wires can be connected to a pacemaker and, if necessary, the heart can be paced throughout the early recovery phase.

Coronary artery bypass surgery-off-pump procedure:

1. Once the doctor has opened the chest, he or she will use a specific device to stabilize the region surrounding the artery to be bypassed.
2. The remainder of the heart will continue to beat and circulate blood throughout the body.
3. The heart-lung bypass machine and the person who operates it may be maintained on standby in case the treatment requires bypass.
4. The bypass graft operation will be performed by sewing one end of a portion of vein or artery over a tiny hole in the aorta and the other end over a tiny opening in the coronary artery right below the obstruction.
5. Depending on the number of blockages and their location, the patient may require more than one bypass graft.
6. Before closing the chest, the doctor will carefully evaluate the grafts to ensure they are functional.

Procedure completion for both methods:

1. The doctor will use thin wires to stitch the sternum together (like those sometimes used to repair a broken bone).
2. He or she will place tubes in the chest to remove blood and other fluids from the area surrounding the heart.
3. The doctor will suture the sternum skin back together.
4. The doctor will insert a catheter into the stomach through the mouth or nose to remove stomach juices.
5. He or she will next place a sterile bandage or dressing on the wound.

What are the indications for pediatric coronary artery bypass surgery (PCABS)?

Pediatric coronary artery bypass surgery (PCABS) was seldom performed prior to the 1970s due to a lack of convincing surgical rationale. The occurrence of coronary artery complications in newly developed procedures for complex congenital heart diseases, such as the arterial switch operation for complete transpositions of the great arteries and the early correction of intrinsic coronary malformations during the infantile period, necessitated the development of PCABS.

The following are the five most common congenital indications for pediatric coronary artery bypass surgery:

• Anomalous origin of the left coronary artery from the pulmonary artery
• Left main coronary trunk atresia
• Acute and late coronary events in the arterial switch operation for transposition of the great arteries
• The ross operation for congenital aortic stenosis complicated by destructive infective endocarditis
• Inadvertent coronary artery injury during heart operation. 

In most cases, direct coronary reimplantation (coronary transfer) and surgical angio-plastic treatments were preferred; nevertheless, PCABS with internal thoracic artery (ITA) grafts can be lifesaving in emergency or severe myocardial hypoperfusion circumstances. Because saphenous vein grafts have lower patency than ITA grafts, they should be avoided in developing children. Using high-power magnifying glasses or a surgical microscope, the technique may be conducted safely on neonates, babies, and small children.

What vessel is used in pediatric coronary artery bypass surgery (PCABS)?

Although PCABS for CHD was first done with autologous saphenous vein grafts (SVGs), the SVG's late destiny was not good in infants with congenital heart disease and inflammatory Kawasaki disease (KD) coronary artery sequelae.

Long-term graft follow-up observations were largely undertaken in children with KD, yielding the following results, which are likely applicable to CHD as well. 

1. The long-term patency of SVGs in pediatric patients over 30 years is suboptimal, particularly when utilized in little children.
2. The long-term patency of internal thoracic artery (ITA) grafts after 30 years in pediatric patients is good, especially in little children.
3. In situ ITA grafts can expand in length (longitudinally) and diameter (circumferentially) with children's somatic growth; the ITA graft is a living conduit.
4. Autologous but isolated SVGs respond poorly to children's body growth and do not expand in length. Intimal hyperplasia and degenerative alterations such as stenosis, elongation, blockages, and aneurysmal dilatation are common in SVGs and can lead to atherosclerosis within 10 to 20 years.
5. ITA grafts can expand or contract in diameter according on the blood flow requirements of the heart's regional area.
6. Although the string-like ITA caused by flow competition between the native coronary artery and the graft is frequently regarded as a failure and disadvantage of the ITA graft, it can occasionally recanalize and resume graft function in children as stenosis of the native coronary lesions progresses.
7. Closure of the ITA graft due to flow competition seldom produces ischemia or ischemic symptoms at first, but may do so later due to graft thrombosis and development of coronary artery lesions, requiring reoperation.

Because of the ITA's exceptional adaptability, an ITA transplanted at a young age can maintain patency even into maturity, as seen by good survival rates in individuals with KD up to 30 years following surgery.

PCABS with ITA grafts for coronary problems during or after CHD surgery in infancy or children may also be able to operate well for extended periods of time, because, unlike KD, there is no distal disease of the coronary artery in CHD, and hence late coronary events may be fewer. Furthermore, when ITA grafts are used, long-term anticoagulation therapy is not required.

PCABS in Anomalous origin of the left coronary artery from the pulmonary artery

The first PCABS for congenital coronary anomalies was performed on ALCAPA to create a double coronary artery system. A research published in 1973 described 6 infants with ALCAPA who were treated by ligation or closure of the left coronary artery origin at the pulmonary artery, as well as saphenous vein grafting. However, the late outcomes were unsatisfactory. The study reported that two grafts were discovered to be occluded, two grafts developed stenosis at the point of the coronary artery anastomosis, and one showed distal dilatation of the SVG among the six patients treated with an SVG.

These findings suggest that SVGs used in pediatrics have poor long-term patency and tended to shut suddenly, with or without clinical manifestations. The first symptom of transplant failure might be sudden death. SVG usage in juvenile patients should consequently be limited or avoided, regardless of the cause of the heart condition.

In 1998, a research demonstrated the effective use of ITA grafts for newborns with ALCAPA. From 11 months to 2 years after surgery, all ITA grafts were found to be patent. Another research published in 2010 found that two infants with ALCAPA who developed critical stenosis after coronary reimplantation were effectively treated with an ITA-left anterior descending artery (LAD) bypass. According to these results, PCABS with ITA grafts might be used in situations of failed or problematic coronary transfer.

According to a recent study, direct reimplantation may be more challenging in adults than in children due to greater coronary artery friability and less flexibility for mobilizing. When direct reimplantation is problematic in individuals with ALCAPA, a coronary bypass may be chosen. In conclusion, while direct coronary reimplantation (transfer) to the aorta should be prioritized, conversion to a bypass with ITA grafts is appropriate for both children and adults with ALCAPA.

PCABS in Congenital Atresia of the Left Main Coronary Artery Trunk

This is an uncommon abnormality that is frequently accompanied with mitral regurgitation. Because of the high likelihood of sudden mortality or the emergence of heart failure and symptoms, prompt coronary artery revascularization surgery is strongly advised for all patients. Depending on the length of the atretic or stenotic lesion from the left coronary ostium to the left coronary bifurcation, surgical angioplasty with different patch materials or PCABS with ITA grafting was used.

Two studies on children treated with left ITA-LAD bypass grafting were published in 1992. The grafts displayed excellent early patency. The 6-month postoperative study demonstrated that the ITA graft, which perfused the whole left ventricle, was in outstanding patency.

According to the numerous findings on congenital atresia of the left main trunk (LMT), single ITA-LAD grafting might be adequate, particularly for pediatric patients, due to the ITA graft's high adaptation to the flow requirement of the left ventricle in growing children. Many successful PCABSs for this entity have been recorded, and the majority of surgeons feel that ITA-PCABS is useful for this problem.

However, other surgeons emphasized that surgical angioplasty may be performed in many patients with this abnormality, saving the ITA for future use. This is a realistic idea, and the surgical choice is influenced in part by the length of the atretic coronary trunk.

PCABS in coronary stenosis and obstruction during and after ASO for TGA complex

Arterial Switch Operation (ASO) has become the method of choice for TGA correction with or without ventricular septal defect and some kinds of double-outlet right ventricle (Taussig-Bing malformation). The quality of the coronary artery transfer determines the success of the arterial switch surgery.

Coronary problems following ASO were responsible for at least 50% of early fatalities and almost 100% of late deaths. Stretching, kinking, compression, and unroofing treatments can produce intimal smooth muscle cell hyperplasia, which leads to stenosis and blockage, especially in neonates and babies.

The TGA complex's coronary origin and course deviate from normal in a variety of ways. Some studies found no link between death rates and anatomic differences of the coronary arteries. However, a study in 1999 found a significant relationship between coronary artery patterns and surgical results in 290 ASO patients. The study discovered that a single right coronary artery, inverted coronary artery patterns, and intramural coronary arteries caused technical challenges for ASO, and that in 8% of such patients, the technique was modified to bypass during the surgery to avoid coronary transfer.

The most common cause of mortality during ASO is ischemic myocardial failure caused by coronary transfer, which results in coronary hypoperfusion. The most prevalent event leading in recent perioperative death of around 7% is difficulty weaning off a cardiopulmonary bypass machine. An emergency bypass with an ITA graft, supported by intraoperative angiography, when possible, is a critical, life-saving treatment in this scenario.

Since 1989, a number of publications on acute coronary transfer issues during ASO have demonstrated that either the subclavian artery or the ITA may be utilized as an emergency coronary bypass graft in the pediatric population, including neonates and infants.

In an emergency circumstance during ASO, revision of the coronary transfer may be required to alleviate myocardial ischemia, albeit time-consuming and with doubtful effectiveness. Cardiopulmonary bypass and cardiac arrest must be extended, and bleeding issues may worsen. In this case, emergency coronary bypass surgery with the ITA is a life-saving technique with a high success rate and favorable long-term outcomes. Because of the thin and soft chest wall in neonates and babies, the ITA is easily visible and accessible without aortic cross-clamping.

Late coronary stenosis or occlusion was relatively uncommon, with more than 11% of patients experiencing the problems more than a year after ASO. Because most children have no symptoms following ASO, a regular coronary imaging examination is advised in all patients.

In one series, late death following ASO occurred in 10% of surgical survivors. The late-death pattern was generally unexpected and abrupt, with no prior signs. Autopsies revealed an acute myocardial infarction caused by coronary stenosis induced by concentric fibromuscular intimal growth.

Because myocardial ischemia symptoms are difficult to detect in infancy, thorough postoperative follow-up is required to prevent late abrupt death. This is especially important during the first 6 months after ASO. When coronary arteriography detects coronary lesions late after ASO, percutaneous coronary intervention (PCI), surgical angioplasty, or PCABS with an ITA graft may be done effectively, depending on the location, length, and character of the lesion (stenosis or occlusion).

Inadvertent Coronary Injuries During Cardiac Operation

When an anomalous main coronary artery is mistakenly wounded, emergency ITA-PCABS is useful as a life-saving treatment, particularly in situations requiring incision and expansion of the right ventricular outflow tract, where the anomalous LAD crosses over.

A research reported effective emergency PCABS with an ITA graft for an unintentionally injured anomalous main coronary artery during an open heart surgery, such as tetralogy of Fallot. The patients were able to effectively recover cardiopulmonary bypass with an emergency PCABS and live. A 30-month follow-up revealed that the ITA grafts were still functional. These anecdotal but significant case reports suggest that in this emergency situation, rapid PCABS with an ITA graft can be a life-saving surgery.

Pediatric cardiac surgeons should be skilled in the rapid and correct removal of the ITA in the event that weaning off cardiopulmonary bypass becomes problematic due to a cyanotic, weakly contracting, and swollen heart.

What are the possible complications of pediatric coronary artery bypass surgery?

The following are some of the hazards associated with coronary artery bypass graft surgery (CABG):

• Bleeding during or following surgery
• Blood clots, which can lead to a heart attack, stroke, or lung disease
• Infection at the site of the incision
• Pneumonia
• Breathing problems
• Pancreatitis
• Kidney failure
• Abnormal heart rhythms
• Failure of the graft
• Death

Conclusion

The operation known as coronary artery bypass graft surgery (CABG) is performed to treat coronary artery disease. Coronary artery disease (CAD) is characterized by the narrowing of the coronary arteries, which are the blood channels that give oxygen and nutrients to the heart muscle. CAD is caused by a buildup of fatty material inside the artery walls. This buildup narrows the arteries on the inside, reducing the delivery of oxygen-rich blood to the heart muscle.

Pediatric Coronary Artery Bypass Surgery (PCABS) with ITA grafts is crucial in saving neonates, babies, and children who have both an intraoperative severe coronary transfer issue and late coronary occlusive disease due to increasing intimal proliferation.

SVGs should be avoided in the presence of growing youngsters. Pediatric cardiac surgeons should be educated for this uncommon but life-saving surgery, and PCABS with the ITA should be regarded as a new arena in current heart surgery for acquired and CHD.