The Heart Center - Arkansas Children's Hospital

Robert D.B. "Jake" Jaquiss, M.D.; Chief, Pediatric and Congenital Cardiothoracic Surgery, Arkansas Children's Hospital; Professor, Department of Surgery, University of Arkansas for Medical Sciences College of Medicine

The Fontan Procedure is an operation which is performed in children whose hearts have only one functional pumping chamber (ventricle) and which allows for virtually all of the venous (blue) blood in the body to flow passively to the lungs prior to returning to the heart. This circulatory arrangement allows for the single ventricle to expend all of its pumping energy on delivering blood to the body, and allows for the near complete separation of the blue and red blood. The name Fontan is applied to the operation in honor of Dr. Francois Fontan, who first demonstrated its feasibility. Since the introduction of the concept into clinical practice by Dr. Fontan nearly 40 years ago, the operation has gone through a series of modifications and improvements allowing its wide application to virtually all children born with single ventricle hearts.

In the evolution of the Fontan operation, among the most important advances was the recognition that achieving the final Fontan circulation is most safely accomplished in stages. For most children, this will translate into three separate operations. The first operation is typically performed in the newborn time frame and is directed at ensuring unobstructed blood flow to the body and blood flow that is pumped to the lungs, but in a regulated fashion. This first operation may be one of several types: a modified Blalock-Taussig shunt, a pulmonary artery band insertion, or some form of a Norwood operation. In all of these cases, blood flow to the lungs must be pumped by the single ventricle (as opposed to the passive lung blood flow after the Fontan operation), because the resistance to blood flow in the newborn is too high to allow passive flow.

After the initial operation and a period of between three and nine months, children are returned to the operating room for a second operation, which is some form of a superior cavopulmonary anastomosis. In this operation (the subject of a previous article in this series), pulmonary blood flow is altered by disconnecting the lung arteries from the pumping source and connecting the superior vena cava to the lung arteries as a new source of blood flow. The superior vena cava is the large vein that returns all of the blue blood from the upper half of the body, which is over 50 percent of the total body blood flow in small infants. This operation reduces the workload of the single ventricle by taking the job of pumping lung blood flow away, but still leaves all the blood from the lower half of the body returning to the heart without going to the lungs.

The final operation is the Fontan procedure, termed by some the “Completion Fontan” in recognition of its place as the last of three procedures, and functionally connects the inferior vena cava directly to the lung arteries. This has the effect ultimately of forcing all of the blue blood to go through the lungs prior to returning to the heart, which is reflected by a 5 to 15 percent increase in the oxygen saturation in arterial blood. Parents often notice that their children are “pink” for the first time in their lives, although this effect often requires several weeks of recovery to be fully realized.

As a technical matter, the Fontan operation is generally accomplished in one of two ways, depending on the particular features of the anatomy of the cardiovascular system, prior operative strategies, and surgeon preference. One approach is known as the “lateral tunnel Fontan” and is generally performed in children whose second-stage operation was a “hemi-Fontan” procedure. In this particular sequence, a portion of the second operation leaves the top of the right atrium connected to the underside of the right lung artery, but with the connection temporarily closed. At the time of the third stage operation, the right atrium is opened and the partition separating the right atrium from the lung artery is removed. A second partition or baffle is then inserted within the body of the right atrium to divert all of the inferior vena caval blood up to the connection between the right atrium and the lung artery. The right atrium is then closed leaving a “lateral tunnel” passageway through the atrium connecting the inferior vena cava to the lung artery.

The alternative approach to the Fontan operation is known as the “external conduit” procedure. In this version of the Fontan, the inferior vena cava is detached from the heart and sewn to a tubular graft, the other end of which is then sewn to the underside of the pulmonary artery. The external conduit approach is typically performed when the second-stage operation has been a bidirectional Glenn operation as opposed to a hemi-Fontan procedure.

Beyond which version of the Fontan operation is performed is the question of whether a fenestration will be added to the procedure. The fenestration refers to a very small connection which is purposefully left or created between the Fontan pathway and the atrium of the heart. The purpose for the fenestration is to allow decompression of the Fontan pathway at times when the resistance to blood flow through the lungs is particularly high, such as immediately after surgery. The pop-off function provided by the fenestration generally has been felt to diminish the risk of Fontan operations and provide for a much smoother, less complicated post-operative course. Use of fenestrations has been shown to reduce the time of chest tube drainage as well, and consequently reduce the length of hospital stay after the Fontan surgery. The only price to be paid for use of a fenestration is a slightly lower initial oxygen level, but this increases gradually over time. If necessary, the fenestration can be closed electively at a later date, although many seem to close spontaneously.

After the Fontan operation, most children will continue to require some medications. Some of these are directed at reducing the tendency for fluid accumulation and others are aimed at increasing the efficiency of the single ventricle. Many children also will be placed on anti-coagulant medications to reduce the chances of clot formation in the circulatory system. It is uncertain how long all of these medications will be necessary, and adjustments will be made by the pediatric cardiologist as the children grow and recover from the surgery.

In summary, the Fontan procedure as it is presently accomplished represents an effective, reliable, and low-risk palliative solution for children with single ventricle hearts. Although the long-term fate of children with such hearts is unknown, the evolution in “Fontan science” will doubtless continue and continue to offer an ever-improving outlook.

Ritu Sachdeva, M.D., Pediatric Cardiologist and Director of Resident Education for Pediatric Cardiology, Arkansas Children’s Hospital; Assistant Professor of Pediatrics, University of Arkansas for Medical Sciences

In 1976, Frazin and colleagues first attached an ultrasound transducer to the tip of a cable for transesophageal imaging of the heart. (1) Since that time several advances in ultrasound technology have occurred, including the miniaturization of the size of the probe and improvements to the flexibility and softness for its application in the pediatric population. The role of transesophageal echocardiography (TEE) during pediatric cardiac surgeries and interventional cardiac catheterization to guide procedures and provide immediate anatomic, functional and hemodynamic assessments is now well-established. (2, 3)TEE complements the preoperative and perioperative evaluation of patients with congenital heart defects and also provides intraoperative echocardiography without interrupting the surgical procedure or introducing additional instrumentation into the surgical field (Fig. 1).

Before the advent of TEE, epicardial imaging was performed using the regular transthoracic imaging probe directly on the heart. Disadvantages of epicardial imaging include invasion of the surgical field, limited windows, possible induction of ventricular ectopic beats and possible transient hypotension. Intraoperative TEE has been used in the care of patients with congenital heart defects since the late 1980's. (4) The first TEE probe for use in children was a single plane probe, but rapid advances led to development of a biplane probe and later a multiplane probe. The multiplane probes that are currently the most commonly used probes provide a circular continuum of two-dimensional transverse and longitudinal images along a 180 arc without the need for reposition of the probe.

Indications for TEE in Pediatric Population (5):
A. Diagnostic indications
1. Patient with suspected congenital heart disease and nondiagnostic transthoracic echocardiography;
2. Presence of patent foramen ovale and direction of shunting as possible etiology for stroke;
3. PFO evaluation with agitated saline contrast to determine possible right-to-left shunt, prior to transvenous pacemaker insertion;
4. Evaluation of intra or extracardiac baffles following the Fontan, Senning, or Mustard procedure;
5. Aortic dissection such as in Marfan syndrome;
6. Intracardiac evaluation for vegetation or suspected abscess;
7. Pericardial effusion or cardiac function evaluation and monitoring postoperative patient with open sternum or poor acoustic windows;
8. Evaluation for intracardiac thrombus prior to cardioversion for atrial flutter/fibrillation;
9. Evaluating status of prosthetic valve.

B. Perioperative indications
1. Immediate preoperative definition of cardiac anatomy and function;
2. Postoperative surgical results and function.

C. TEE guided interventions

Figure 2a:Image showing a secundum atrial septal defect measuring 7.6 mm, between the left atrium (LA) and the right atrium (RA)

Click here for Hi-Res Photo

1. Guidance for placement of atrial septal defect occlusion device (Figs. 2a and 2b);
2. Guidance for blade or balloon atrial septostomy;
3. Catheter tip placement for valve perforation and dialation in catheterization laboratory;
4. Guidance during radiofrequency ablation procedure.

Figure 2b: Arrow points to the two discs of the device used to close the atrial septal defect in the cardiac catheterization lab

Click here for Hi-Res Photo

Contraindications:
Esophageal strictures, active gastrointestinal bleeding, unrepaired or recently repaired tracheoesophageal fistula, recent Nissen fundoplication, severe respiratory decompensation or poor airway control. Some relative contraindications are
esophageal varices, esophageal diverticulum, cervical spine injury or deformity, oropharygeal deformity and severe coagulopathy.

Performing the examination:
TEE is a semi-invasive procedure and should be performed only by a physician trained to do it. In addition to the cardiologist performing the test, another physician, preferably an anesthesiologist who is skilled in pediatric airway management and resuscitation, should be present to monitor the patient. The procedure is performed under conscious sedation or general anesthesia, depending on the circumstances of the procedure. The Pediatric Council of the American Society of Echocardiography selected a task force to create a position statement specifically for the performance of TEE in this select category of patient. This statement reviews current indications, contraindications, safety issues and training guidelines for TEE in the pediatric patient with heart disease. (5)

Complications:
Incidence of serious complications with TEE is low. In several pediatric series the incidence of complications has been reported to range between 1.6 to 4.9 percent. Most have been minor and without sequelae. The most frequent complication in the pediatric age group is airway compromise. Minor complications include transient arrhythmias, minor pharyngeal bleeds, dental trauma, transient hypotension and throat discomfort. More serious complications include esophageal perforation, airway compromise and even death in rare instances. These complications can be avoided by carefully selecting the appropriate size probe, ruling out any contraindications to TEE as mentioned above, using the appropriate manipulation of probe and effective monitoring by a trained person during the procedure.

Miniaturized TEE:
A miniaturized ultrasound transducer-tipped catheter, designed primarily for intracardiac use, has been used to perform TEE especially in the neonates where a regular probe can not be inserted. This single-plane probe has a transducer affixed to the end of a 10F, 3.3-mm diameter catheter, which is 90 cm in length (Fig. 3). It has full spectral and color

Doppler capabilities. This multifrequency (5.5-10 MHz) probe provides images at distances from 1 mm to 12 cm from the catheter-tip surface. The two major disadvantages of this probe are that it lacks horizontal plane imaging and does not have a thermistor to measure probe tip temperature. Preliminary animal model studies by Bruce and colleagues using this probe have established its safety for TEE in rabbits weighing between 400 and 3000 g. (6) Bruce at al then reported the first pediatric transesophageal use of this probe demonstrating its safety and clinical application in the neonatal and infant population, their youngest patient weighing 2.1 Kg. (7) The very small size of the probe allows imaging of patients in whom standard TEE was not tolerated or able to be performed.

3-Dimensional TEE:
There now are transesophageal probes available for providing three-dimensional cardiac images in adults. Some require separate software for reconstruction of images acquired during the study, thus not providing instantaneous results as required in the operating room. The more recent ones can provide live 3D images offering immediate results. However, this technology is still not widespread and there is only limited availability for pediatric population.

Umesh Dyamenahalli, M.D.; Pediatric Cardiologist and Cardiac Intensivist, Arkansas Children’s Hospital; Assistant Professor, Echocardiography, University of Arkansas for Medical Sciences College of Medicine.

Incidence of congenital heart defects:
Six to eight out of every 1,000 babies born in the world, including in the United States, have major congenital heart defects (CHD) which are detected either during pregnancy or after birth. Congenital heart defects are the most common birth defects and remain the leading cause of death in childhood.

Causes of congenital heart defects:
There is no definite single cause identified; however, some CHDs may have a genetic link, either occurring due to a defect in a gene, a chromosome abnormality or environmental exposure to certain infections and toxins such as alcohol and some of the medications during early pregnancy which cause heart problems to occur. Other times, this heart defect occurs sporadically (by chance), with no clear reason for its development.
Truncus Arteriosus is one of the rare but major congenital heart defects. This condition might make up 1 to 2 percent of all incidents among children with CHDs (0.034/1,000 live births).

Definition
Truncus Arteriosus is a common trunk that exits from the base of the heart through a common arterial valve and gives rise directly to systemic, pulmonary and coronary circulations. In addition, there is a large hole in the ventricular septum called a Ventricular Septal Defect (VSD).

Why does it occur?
In early fetal life, the aorta and pulmonary artery starts as a single blood vessel, which eventually divides and becomes two separate arteries. Truncus arteriosus occurs when the single great vessel fails to separate completely, leaving a connection between the aorta and pulmonary artery.
The valve of the Truncus Arteriosus (Truncal Valve) can work normally without any leak or obstruction to the flow. A Truncal valve usually has three or four leaflets, but can have two or five leaflets. The valve leaflets, however, can be abnormally thickened, causing obstruction to blood flow as it leaves the heart; it can also leak, causing blood that leaves the heart to dump back into the pumping chamber across the leaky or insufficient valve.
Asssociated cardiac lesions: Other important heart problems that may be seen in association with truncus arteriosus include abnormal coronary arteries and aortic arch anomalies (narrowing or complete interruption of the aortic arch)
Associated noncardiac conditions: Noncardiac lesions can be present in about a third of patients. One of the most significant associated genetic defects is DiGeorge Syndrome. These patients have deletion of chromosome 22q11. Di George syndrome is characterized by a varying degree of small mandible, abnormal face and low-set posteriorly rotated ears. They often have hypoplastic thymus and parathyroid glands that can result in immunodeficiency and low calcium. Other associated defects can be cleft palate and kidney abnormalities.

How do these patients present?
Babies born with this heart defect usually develop signs of congestive heart failure in the first week or two of life. Most often parents report rapid breathing, chest wall retractions, restlessness, poor feeding and bluish color of the skin, especially around the mouth and nose. The signs and symptoms often increase during feeds. These babies often fail to gain weight. Their oxygen levels are often slightly lower than normal and may result in cyanosis.

Why do they develop problems and need surgery?
The truncal Valve is directly above the Ventricular Septal Defect; blood is pumped from both the right and left ventricles (RV and LV) to the lungs and to the body. The mixing of oxygen-rich (arterial) and oxygen-poor (venous) blood reduces the efficiency of the circulatory system. Pulmonary (lung) resistance is lower than systemic (body) resistance. Therefore, there is usually increased blood flow to the lungs. This increased pulmonary blood flow can lead to congestive heart failure. Because the lung arteries are connected to the high pressure pumping chambers (ventricles), there is high blood pressure in the lung arteries. If we do not treat this defect by surgery, the lungs are exposed to both high pressure and extra blood flow for an extended time (months to years), irreversible pulmonary hypertension can occur.
Physical findings: Most babies with truncus arteriosus are born at term and are usually near normal in weight and length. After birth, the baby’s lips and fingernails may look blue. A heart murmur is most often present. If congestive heart failure is present, the heart rate and breathing rate will be increased, and the liver may be enlarged.

How is this heart defect diagnosed?
Prenatal diagnosis: Truncus arteriosus can be diagnosed before birth by a fetal echocardiogram (a heart ultrasound) as early as 16 to 18 weeks into the pregnancy.

This test is done when there is a family history of congenital heart disease or when a question is raised during a routine prenatal ultrasound.
Postnatal diagnosis: The suspected diagnosis is confirmed by an echocardiogram. Other tests include an electrocardiogram and chest x-ray: In the chest X-Ray the heart looks big and the lung fields look hazy indicating too much of blood flow to the lungs due to pulmonary overcirculation, and increased lung edema.
Rarely a heart catheterization may be needed to help in planning the surgery.

How Is It Treated?

The major treatment for truncus arteriosus is open-heart surgery, done usually in the neonatal period. Surgery includes closing the VSD using a patch (Dacron), removal of branch pulmonary arteries from the trunk and inserting a conduit from the right ventricle to the pulmonary (lung) arteries. [Conduit is made of either Dacron with a pig valve inside it or a donated human valve and an artery (called a homograft)]. Sometimes repair or replacement of the truncal valve is needed as well.
This is among one of the more complicated procedures to be performed on a newborn, and babies can be very sick needing breathing support and other medications to help the heart to function better in the first few days after the operation. They will be in an intensive care unit and looked after by specialized doctors and a nursing team. The postoperative hospital stay is variable in length, depending on associated problems.

Do they need any medications prior and after the operation?
Medicines such as digoxin and lasix are often used to treat symptoms of congestive heart failure.

Do they need any more heart surgeries after the initial operation?
Most children with truncus arteriosus will need their conduit/homograft replaced one or two times before they reach adulthood. This is needed because the child “outgrows” the conduit and also because conduit may degenerate, and calcium tends to collect in the conduit causing a narrowing and thus obstruction to blood flow. Re-operation to replace the conduit is usually tolerated well and carries a lower risk for complications.

Are there any long-term health issues for children with truncus arteriosus?
The surgical success for early repair of truncus arteriosus in babies has improved greatly with 85 to 90 percent survival. Re-operation to replace the conduit will be needed periodically, but these operations are quite low risk to the child.

Endocarditis prophylaxis: Throughout their lives, children with truncus arteriosus are at an increased risk for bacterial endocarditis (SBE). This is an infection of the heart caused by bacteria in the blood stream. Children with heart defects are more prone to this problem because of the altered flow of blood within and out of the heart. It can occur after dental work or medical procedures on the gut or respiratory tract because these procedures almost always result in some bacteria entering the blood. SBE can usually be prevented by taking an antibiotic before these procedures.

Exercise guidelines: An individual exercise program is best planned by discussing with the doctor so that all factors can be included. Children with truncus arteriosus are usually restricted from vigorous or competitive sports but can participate in recreational sports. It is important for them to always be able to self-limit their activity; that is, they should rest whenever they feel the need to do so. The children can usually participate in gym class but should be allowed to self-limit their level of exertion, and they should not be graded, which could increase the pressure to exceed their natural limits.

Spotlight on Xiomara Garcia, M.D., Pediatric Cardiologist, Arkansas Children’s Hospital.

What drove you to become a physician?
I became a physician because I like to take care of people and make them feel better.

Why did you choose the ACH Heart Center as the place to practice medicine?
The reason why I came to this program was that I heard that ACH was one of the best children’s hospitals in the United States. Also, because as a foreign doctor, Arkansas Children’s Hospital gives you the opportunity to work in this institution, of course after a extensive evaluation of your training, and at the end of the road if you work hard and show your professionalism you can stay in the United States forever.

How is heart care for children different from heart care for adults?
I think that taking care of children is completely different from adults. They are easier to work with (always smiling, less heavy, easy to move around), they also most of the time get better, even when they are very sick, and recover faster than adults recover. When you take care of a sick child, you also are taking care of the family, and the goal for me is to keep them together, as they were before the child got sick, so they can enjoy the wonders of life.

Do you have a general patient story that continues to inspire you to practice medicine?
I remember back in my country having a lot of trouble taking care of patients with congenital heart disease, mainly because it is a long-term process, very expensive, with many requirements that a third world country can not afford. I had several children die waiting for surgery; that made me come to this country to be trained in Pediatric Critical Care Cardiology, mainly on the post-operatory care of these very sick children with heart defects.

How do you think the ACH Heart Center makes a difference in the lives of children?
I think the ACH Heart Center makes a difference in the lives of children because there is a group of people (doctors, nurses, nurse practitioners, respiratory therapists, hemoperfusionists, social workers, secretaries, all the coordinators and even the people who keep our environment clean and organized) who care about children with all kinds of heart defects. And we give them a better chance to live a “normal life” that otherwise would not be impossible.