|
 |
|
|
|
|
Adults with "Corrected" Congenital Heart Disease
David Z. Friedberg, MD
When surgical procedures for both simple and complex congenital cardiac lesions first were performed, it was believed such surgeries resulted in a "cure" or complete repair. However, it has become obvious such surgeries rarely achieve a cure, but rather relieve the abnormal physiology and allows the patients to lead what we consider a normal life with minimal limitations. As these patients age, however, an increasing number of residual and new problems have been noted.
Transposition of the great arteries
Prior to the description by Dr. Jatene of the arterial switch procedure for correction of transposition, the surgical technique employed was the "venous switch." Although a variety of surgical techniques were utilized, all aimed to baffle systemic venous blood to the mitral valve and pulmonary venous return to the tricuspid valve. This resulted in a physiologic correction with desaturated blood relegated to the lungs and saturated blood coursing to the aorta. The two techniques used to accomplish this were the Mustard and Senning procedures. At Children's Hospital of Wisconsin, the first Mustard procedure was performed in 1973. Since then, 70 children have undergone that procedure. The first Senning operation was done in 1982; 64 children have had this procedure since then.
Although the patient has normal arterial saturation, the venous switch relies on the right ventricle to perform at systemic pressure and resistance. As these patients grow older, the right ventricle dilates. In some, tricuspid insufficiency develops and in others there is right ventricular or systemic ventricular failure. End-stage heart failure requires a cardiac transplant. Another option for relief of systemic ventricular failure involves takedown of the Mustard or Senning baffles, preparation of the left ventricle with pulmonary artery banding and then a Jatene arterial switch procedure.
The other major problem older patients with long-term Mustard or Senning procedures experience is atrial arrhythmia. Sinus node disfunction has been reported in more than half of these patients and may include bradycardia, sick sinus syndrome and tachycardia. Atrial arrhythmias such as flutter/fibrillation also are reported and may lead to rapid ventricular response and ventricular fibrillation.
Tetralogy of Fallot
Tetralogy of Fallot, and its variants, is the most common cyanotic cardiac lesion. It occurs in nearly 10 percent of children with congenital heart disease. Corrective surgery has been available for more than 35 years and there now is a large number of adults who have had successful repairs. However, there are numerous concerns about late sequellae of surgery.
Arrhythmias constitute a significant cause of morbidity in these patients. Ventricular arrhythmias such as premature ventricular contractions and ventricular tachycardia are common and ventricular fibrillation has been described as a cause of sudden death. Some of these patients have undergone electrophysiologic studies with attempted ablation of sites believed to initiate the arrhythmias. In others, internal cardiac defibrillators have been inserted. Many patients are receiving antiarrhythmic drugs which, themselves, also are proarrhythmic. The occurrence of arrhythmias more commonly is seen in those patients who have residual anatomic or physiologic lesions after repair, such as pulmonary stenosis or insufficiency and ventricular septal defects.
Relief of pulmonary valve and subvalve stenosis is necessary for successful correction of tetralogy of Fallot. In addition to resection of muscle from the septal and parietal bands of the right ventricular outflow tract, it is often is necessary to enlarge the pulmonary valve annulus by incising the ring and inserting a transannular patch. Pulmonary insufficiency may develop, leading to right ventricular dilatation, tricuspid valve insufficiency and right ventricular failure. Insertion of a homograft valve then is required. These valves often deteriorate and require repeat surgery for replacement.
In spite of these problems, long-term survival of patients who have had surgical correction of tetralogy is excellent, with some reports of late survival as high as 90 percent after 30 years.
Fontan procedure
The Fontan procedure first was developed in 1971 for palliation of tricuspid atresia, but now is employed for all varieties of single ventricle anatomy. Long-term observation has not been possible in part because of numerous changes in technique and indications for surgery, but already post-surgical sequellae have and are being documented. These include:
- Systemic ventricular failure in patients with single right ventricle and/or hypoplastic left ventricle.
- Peripheral edema; hepatomegaly with reduced hepatic function and protein-losing enteropathy.
- Development of thrombi within the right atrium or Fontan baffle.
- Development of systemic venous collateral channels causing systemic desaturation.
While the Fontan procedure offers the patient with a functional single ventricle the opportunity for improved oxygen saturation and function, there are multiple problems that can be expected in the future.
Post-operative sequellae in other lesions
Post-operative sequellae have been noted even in simple congenital lesions.
For example, there are patients with repaired coarctation who remain with transverse aortic arch hypoplasia and who have significant hypertension on exertion. Some patients who had coarctation repaired using a dacron patch have developed an aneurysm at the site of the repair. Patients with critical aortic stenosis who undergo a surgical valvotomy or balloon valvuloplasty may develop aortic insufficiency of a significant degree. Finally, even patients who are post operative repair of secundum atrial septal defects have been reported to have atrial arrhythmias and sinus node dysfunction requiring a pacemaker.
It would be a mistake to become discouraged about surgical repair for congenital heart disease. Advances in surgical technique and post-operative care have allowed thousands of children to lead normal lives and reach adulthood. However, such surgery rarely repairs a lesion completely. These hearts never are normal and patients require cardiac follow-up throughout their lives. |
 Back to Top
 |
|
|
Chris Brzakala, RN, cardiovascular nurse clinician |
|
In August, James Tweddell, MD, perfusionist Christopher Brabant and I took part in a medical mission to Trinidad through Caribbean Heart Menders.
This group was created by a Jamaican native and nurse, Brenda Forrest, to provide children in the Caribbean with needed surgery. Forrest's daughter, now 15, was born with tetralogy of Fallot and had to travel to the U.S. for her operations. Forrest created this association so children can receive medical care without being separated from their families.
Trinidad, formerly a British island, is an independent democracy a few miles off the coast of South America. It is home to about 1.3 million people from India, China, Africa and the Mediterranean. The climate is very warm with an average daily temperature of 83º and 100 percent humidity. Local industries include oil, natural gas, iron, steel and a brewery.
While we were in Trinidad, we treated nine children from 14 months to 16 years of age. Open-heart procedures included repair of ASDs, VSDs, placement of a Glenn shunt and an aortic valve replacement. All children had a physical and dental exam before surgery.
I was one of eight intensive care nurses on the team. We were responsible for postoperative care in the intensive care and acute care units as well as training local nurses. We also taught parent classes that included pre-, postoperative and discharge management as well as dental hygiene and nutrition.
Most of the supplies for the operating room and ICU were supplied by Caribbean Heart Menders. The four ICU rooms were equipped with a bedside monitor, one infusion pump, a Bear 5 ventilator and a power column similar to those in our PICU. Caribbean Heart Menders supplied four syringe pumps and three pulse oximeters. Only two of the children used syringe pumps and we rotated the use of the POXs. There was a shortage of linens and personal hygiene items as well as gauze, tegaderm, syringes and antibiotics.
All the children had their invasive lines removed, were out of bed the first day postop and were encouraged to begin PO fluids. Jvac drains were used to drain the mediastinum and no pleural tubes were used. Most of the drains were removed by the end of the first post-op day.
The acute care unit was wide open with the sun shining in open windows. There was enough space for parents to stay with their children.
The families were so gracious and so thankful, we all came away with a lot more than we gave. It was an experience I will never forget. | |
| |
Back to Top
|
|
|
Dick Berens, MD, chief of staff |
|
|
|
Sedation management of pediatric cardiac surgical patients depends on a wide spectrum of variables including patient age, complexity of heart and other disease, preoperative congestive heart failure and cyanosis, previous medications and the dosage ranges and side effects of the sedating agents used.
In some patients, psychotropic medication (benzodiazepines, opiates, chloral hydrate) use begins in the preoperative period and extends well past discharge from the hospital. The patient with a prolonged hospital stay may require several classes of medications.
A team approach is best for assessing the perioperative course for each patient. This multidisciplinary cardiac team includes cardiac surgeons, cardiologists, anesthesiologists, critical care physicians, pediatricians, nurses, surgical and cardiac cath lab technicians and perfusionists. The team should evaluate preoperative heart disease, the patient's physiologic state, the psychological condition of the patient and parents, the planned intraoperative course and the likelihood of a short or protracted recovery period. Early extubation or prolonged need for mechanical ventilation likely will determine the use of postoperative psychotropic medication.
Next, the anesthesiologist prepares a perioperative care plan, which includes opiate administration, including route, dosage and duration of use. Once the operative course is under way, the anesthetic plan is adjusted to account for changes in the patient's hemodynamic course or any surgical modifications made due to intraoperative findings or events.
Opiate administration provides a significant adjunct to the perioperative pharmacological plan. Opiates provide profound analgesia, mild to moderate sedation, but no amnestic properties. They are useful intraoperatively for blunting hemodynamic response to intubation and surgical incision as well as diminishing the irritation and pain from incisions, endotracheal tubes and chest tubes after the operation. Opiates work by binding at a variety of receptor sites (table 1) which are responsible for mediating pain relief along with secondary effects (table 2). The medications either are natural derivatives of opium such as morphine and codeine, or are related synthetic agents such as fentanyl, sufentanyl and meperidine.
|
|
Table 1
| Receptor |
Prototype agonist |
CNS location |
Effects |
 |
morphine, fentanyl, meperidine, codeine,methadone, hydromorphone |
Brain
Laminae III or IV of the cortex
thalamus, periaqueductal gray |
u1 - supraspinal analgesia dependence
u2 - respiratory depression, inhibition |
 |
ketocyclazoncine
dynorphin
? Butophanol |
Brain - Hypothalamus, periaqueductal gray,claustum
Spinal cord - Substantia gelatinosa |
Spinal analgesia, ++++ sedation, miosis,inhibition ADH release |
 |
Enkephalins
|
Brain - Pontine nucleus, amygdala, olfactory bulbs, deep cortex |
Analgesia
euphoria |
 |
phencyclidine?
Ketamine |
|
Dysphoria, hallucinations, psychomotor stimulation | |
 |
Table 2
| CNS |
Respiratory system |
Cardiovascular system |
Gastrointestinal system |
Urinary system |
| Analgesia |
Antitussive |
Bradycardia |
Decreased motility and peristalsis |
Increased tone in ureters, bladder and detrusor muscles |
| Sedation |
Decreased minute ventilation, respiratoryrate and tidal volume |
Tachycardia (meperidine) |
Increased tone of sphincter of Oddi |
|
| Nausea and vomiting |
Depresses ventilatory response to carbondioxide and oxygen |
Histamine release (morphine) |
|
|
| Miosis |
|
Minimal effects on cardiac output, exceptmeperidine |
|
|
| Seizures |
|
|
|
|
| DysphoriaEuphoria |
|
|
|
|
| Psychotomimetic behaviors, excitation |
|
|
|
| |
|
The dose response of opiates changes with patient age and physiologic condition. Neonates develop a higher CNS level and decreased respiratory drive compared to adults given the same IV dose per kilogram of body weight. This discrepancy is thought to be secondary to blood brain barrier defect. Neonates also have a prolonged elimination half-life of morphine.
A patient's preoperative physiologic status helps the anesthesiologist decide dose and potency of intraoperative opiates. Patients with significant congestive heart failure or pulmonary artery hypertension may best be served with a combined high dose fentanyl-muscle-relaxant-vapor anesthetic followed by postoperative controlled ventilation in the Pediatric Intensive Care Unit. At fentanyl doses of 25 to 75 mcg/kg, minimal cardiovascular depression occurs with blunting of the stress response to surgical stimuli in neonates. On the other hand, patients in good physiologic condition undergoing a completion Fontan procedure may benefit from early extubation. This is best achieved by using an intraoperative anesthetic technique of oxygen, potent vapor anesthetic and muscle relaxants, with either titration of intravenous opiates or epidural opiate administration.
Critical care physicians and anesthesiologists work together in the immediate postoperative period to provide a smooth transition from the operating room to the intensive care unit. Once in the PICU, the patient's condition dictates the continuation of opiates.
Patients who receive epidural opiates usually are given a single dose in the operating room. These opiates have a duration of up to 24 hours. Patients are followed by the anesthesiologists or pain service through the first postoperative night. The addition of opiates and sedatives on top of the epidural opiates may lead to significant respiratory depression and subsequent reintubation or respiratory arrest.
Patients extubated in the operating room may be placed on intermittent opiates for postoperative pain management. Pain can be managed by nurse-administered opiates or patient-controlled analgesia (PCA) in children of appropriate age and mentation. The usual postoperative pain course peaks in the first 48 to 72 hours with most patients weaned to oral medications by three or four days postop. Patients then are given intermittent benzodiazepines and extra opiates when chest tubes and intracardiac lines are removed. When the child is ready to be discharged from the PICU, analgesics may be reduced to oral opiates or NSAIDS.
The final patient group includes children in need of prolonged postoperative ventilatory management. Patients recovering from TOF, Norwood procedures, arterial switches and AV canals predictably require postoperative ventilatory support and IV opiates for many days after surgery. Due to prolonged continuous opiate exposure, these children may develop a tolerance after a few days, prompting either a higher dose of the same medication or a medication added to the regimen. If left on the agents for too long, the patients develop a tolerance to the opiates. As the patient's condition improves, the amount of opiate medication gradually is decreased to wean the patient from the ventilator and return him or her to an opiate-free state. It is essential to evaluate the opiod-tolerant child for signs of agitation, which may be an indication for reinstitution of medications and prolonged weaning program. | | |
Back to Top
New Servo 300A Ventilators
Chris D. Richey, RRT, PICU resource specialist
The Respiratory Care Department at Children's Hospital recently acquired three Servo 300A ventilators. This newest generation ventilator optimizes patient compliance and comfort while minimizing the time the patient is intubated and ventilated.
The 300A is an upgrade from the 300 version. The "A" stands for automode, which allows the patient to be ventilated by pressure support or volume support. This allows the children who spontaneously breathe to generate their own tidal volume while guaranteeing a minimal set minute ventilation.
Using this ventilator, cardiovascular patients can begin weaning as soon as they begin spontaneously breathing. Since there is less fighting, sedation can be reduced, which also improves weaning. Since our goal is to wean the patient as soon as possible, the automode helps us determine when the patient is ready.
The automode adapts to a patient's spontaneous breaths by automatically switching between the support mode during spontaneous breaths and the control mode when the patient becomes tired and needs assistance.
This ventilator helps support goals of early weaning, optimizing patient comfort, using lung protective strategies and decreasing ventilator days. |
|
|
|
|
 Back to top
|
|
|
|
