The Heart Center - Arkansas Children's Hospital

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Vol 2 Issue 2	March 2007
Inside this issue
Management of a Newborn Suspected of Having Congenital Heart Disease
Malignant Hyperthermia: What We Have Learned
Reducing Blood Stream Infections in the CVICU
Heart Center Staff Sharpens Skills at Conference
The Heart Center Beats Along With Many Activities
Spotlight on Shelby Norfleet
Spotlight on Maria Bode

Management of a Newborn Suspected of Having Congenital Heart Disease

Eudice E. Fontenot, M.D.

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Eudice E. Fontenot, M.D.; Pediatric Cardiologist, Arkansas Children’s Hospital; Associate Professor of Pediatric Cardiology, University of Arkansas for Medical Sciences College of Medicine.

Congenital Heart Disease is the most common birth defect in newborns. Heart disease affects approximately eight out of every 1,000 live births for an incidence of 0.8 percent. More and more, the diagnosis of congenital heart disease is being made prenatally. When a prenatal diagnosis of heart disease is suspected, prearranged plans are made for the baby to be delivered at or near a center capable of caring for the baby. This brief article will discuss the evaluation and management of the newborn with suspected congenital heart disease, when the diagnosis has not been established prenatally.

A Common Scenario

Imagine the following: A nurse from the newborn nursery notifies you that a baby under your charge is quietly tachypneic. The systemic saturation was measured to be 85 percent on room air. The pregnancy and delivery were uncomplicated. What are you thinking and how do you respond to this information? The diagnostic differential for this baby includes either pulmonary or cardiac disease. A few simple tests, available in every hospital, can be performed within a few minutes to aid in the diagnosis. Blood pressure should be measured in both arms and a lower extremity. Systemic saturation should be measured in the right arm and a leg. A plain film chest X-ray is very helpful. Another simple test is an oxygen challenge test. With a pulse oximeter on the right hand, the baby should be given supplemental oxygen as close to 100 percent as possible. These simple tests will help differentiate between hypoxemia that is secondary to a pulmonary cause verses hypoxemia that is secondary to congenital heart disease. Accurate blood pressure measurements from the arms and legs will help diagnose an infant with coacrtation of the aorta. A systolic pressure difference of less than 20 mmHg between the upper and lower extremities is suspicious for coacrtation of the aorta. A chest X-ray gives the practitioner a look at the heart size as well as pulmonary vascular markings. Space occupying lesions such as an unsuspected diaphragmatic hernia, bronchogenic cysts or things like pneumothoraces can be easily diagnosed on a standard AP chest X-ray. The response to supplemental oxygen is also helpful in differentiating between a pulmonary cause or cardiac cause for hypoxemia. Hypoxemia related to intrapulmonary shunting can usually be easily overcome with supplemental oxygen. On the other hand, hypoxemia related to congenital heart disease responds very poorly or sometimes not at all to supplemental oxygen.

Emphasis on the Physical Exam

The physical examination of these babies is important. Generally, infants with hypoxemia related to congenital heart disease have a quiet or resting tachypnea, whereas, babies with hypoxemia relating to pulmonary disease are generally in more respiratory distress. Inspection of the chest and abdomen for symmetry is important. Auscultation of the heart and lungs is done with specific attention to the cardiac rate and rhythm to be sure the heart rate is not too fast or too slow. The presence of a cardiac murmur may lead one to consider congenital heart disease; however, there are several cardiac conditions that can result in significant hypoxemia where there may be no murmur. Assessment of the adequacy of cardiac output can be done simply by measuring the volume of the pulses, assessing the temperature of the distal extremities and testing for capillary refill time.

For the infant with suspected congenital heart disease, a call to a pediatric cardiologist early in the evaluation is helpful. Transport to a medical center with pediatric cardiology services is crucial and should be performed as early as possible. An infusion of prostaglandin (PGE) should be ordered for any newborn suspected of having congenital heart disease. The drug must be given parentally and the dose should start at .05 to .1 micrograms per kilogram per minute. One of the adverse affects of PGE can be central apnea, so one must be prepared to manage the airway of the infant in whom a PGE infusion has begun. Prostaglandins will maintain patency of the ductus arteriosus. In infants whose heart disease results in limited or inadequate pulmonary blood flow, the ductus will allow left to right flow from the aorta through the ductus into the pulmonary arteries to maintain adequate pulmonary blood flow. A common example of this would be the infant with tetralogy of Fallot who has severe right ventricular output obstruction. In infants who have restricted or inadequate flow into the aorta, patency of the ductus will also allow for adequate perfusion to the aorta and the body in the form of a right to left shunt or flow from the pulmonary artery through the ductus into the aorta. In either case, maintaining patency of the ductus in these babies is life-saving. Supplemental oxygen should be used to maintain the 02 saturation between 75 and 85 percent

Using Tools That Work for You

By now, the reader has recognized that this cardiologist has not recommended an ECG or an ECHO. The decision to start PGE in the newborn should be based on the suspicion of congenital heart disease. Waiting to establish a diagnosis is waiting too long. The diagnosis can be established when the patient arrives to the cardiac center. If the echocardiogram at the cardiac center shows a structurally normal heart, the PGE can simply be discontinued and referral made to the appropriate service to manage the baby. One quick note: There is no cardiac condition that is going to be made worse by starting PGE.

As a young house officer, I was taught never to order a test that I could not interpret. What I learned was to use the tools and tests with which I was comfortable. Measurement of heart rate, blood pressures, pulse oximetry and response to oxygen are done with standard tools and tests available in any hospital and can be interpreted by any physician caring for newborns.

Malignant Hyperthermia: What We Have Learned

Luis M. Zabala, M.D.

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Luis M. Zabala, M.D.; Pediatric Cardiothoracic Anesthesiologist, Arkansas Children’s Hospital; Assistant Professor of Anesthesiology, Section of Pediatric Cardiac Anesthesiology, University of Arkansas for Medical Sciences.

Malignant hyperthermia (MH) was first described by Denborough et al in 1961; Melbourne, Australia (1). The authors reported a case of unusual elevation of body temperature (hyperthermia) in one patient after receiving general anesthesia with halothane for repair of a fractured tibia. During preoperative evaluation, the patient reported concern about receiving general anesthesia because ten of his family members developed uncontrolled hyperthermia and died during general anesthesia with ether. In this case, halothane was given as a new alternative to ether and rapidly discontinued when intraoperative hyperpyrexia was noted. The patient was packed with ice and recovery was favorable. Subsequent cases of anesthetic-related fulminant hyperthermia accompanied by muscle rigidity were reported in the 1960s. Because of the overall mortality of greater than 80 percent and the consistent presence of elevated body temperature, this syndrome was referred to as Malignant Hyperthermia. Today MH is known to result from alterations in a specific gene (in genetically susceptible individuals) that produces symptoms once exposed to inhaled anesthetic drugs and a certain paralyzing drug. The exact incidence of MH is unknown. However, the rate of occurrence has been estimated to be as frequent as one in 5,000 or as rare as one in 65,000 administrations of general anesthesia with triggering agents, as published by the Malignant Hyperthermia Association of the United States (www.mhaus.org) (2).

Mortality from MH has declined since first described in the 1960s and is now estimated to be less than 5 percent. This statement derives mainly from advances in monitoring technology and the widespread awareness of its existence. In addition, aggressive personnel education and the approval by the US FDA (1979) of dantrolene sodium IV for the treatment of acute MH has altogether made possible the early detection and treatment of suspected acute MH crisis (MHC). However, it is important to realize that even when recognized promptly and treated correctly, MH can cause multi-organ failure, and ultimately death, in the susceptible individual.

About MH Susceptibility

MH susceptibility is inherited with an autosomal dominant inheritance pattern, meaning that the children from individuals with MH susceptibility have a 50 percent chance of inheriting a gene defect for MH and hence would also be MH susceptible. The rate of spontaneous mutation is unknown but is probably less than 10 percent. The gene is located on the long arm of the nineteenth chromosome (19q13.1). These mutations tend to cluster in one of three domains within the protein (Ryanodine receptor or calcium release channel) designated MH 1 – 3 (3 - 5). The greater part of MH-susceptible patients is phonotypically normal and will only manifest the clinical syndrome once exposed to anesthetic triggering agents.

The primary biochemical abnormality responsible for MH is the inability of the MH-susceptible skeletal muscle to adequately regulate calcium concentrations in the sarcoplasm. An abnormally high concentration of calcium is released from the sarcoplasmic reticulum (SR) into the sarcoplasm when exposed to an anesthetic triggering agent. The calcium overload initiates an exaggerated contractile activity in the MH-susceptible muscle that results in hyper-rigidity, heat production, increased oxygen consumption, anaerobic metabolism and rapid production of lactic acidosis. The calcium release channel or Ryanodine receptor (RYR) is the primary mechanism by which calcium stored in the SR is released into the sarcoplasm during the normal excitation-contraction process. An inherited mutation in the gene for the RYR that resides in the membrane of the SR is believed to be responsible for the abnormally increased release of calcium into the sarcoplasm. In vitro biopsy specimens isolated from MH-susceptible skeletal muscle demonstrate an increased sensitivity to various MH triggering drugs including caffeine, succinylcholine, and halothane. Other potent inhaled anesthetic agents such as Enflurane, Isoflurane, Desflurane, Methoxyflurane and Sevoflurane also cause high concentration of calcium ions to accumulate in the sarcoplasm of MH-susceptible muscle. So, all volatile anesthetic agents and the depolarizing muscle relaxant succinylcholine are considered MH triggering agents.

Clinical Presentation

The clinical presentation of MH is somewhat heterogeneous and nonspecific. Patients differ greatly in their rate of symptom development. A person may have undergone general anesthesia in the past without evidence of MH and develop fulminant MH during their next exposure to inhaled anesthetic agents. Previous exposure to anesthesia does not automatically guarantee the absence of MH-susceptibility of an individual (4). Family history during the pre-anesthesia evaluation is still the best screening test available. However, the gold standard for determination of MH susceptibility is the caffeine-halothane contracture test from skeletal muscle biopsy. Mutation analysis has recently become available in the United States and is expected to play an integral role in the diagnosis of MH susceptibility in the future (5).

The classic clinical features of acute MH comprise a rapid and sustained rise in core body temperature to 39.5 C or greater, increase in metabolism characterized by elevated arterial (PaCO2) and end tidal CO2 (ETCO2), tachycardia and clinically significant contracture of skeletal muscles. In some instances, marked localized muscle contraction (masseter spasm) during the induction-intubation sequence may represent the first clue of MH-susceptibility. If clinical signs (tachycardia and hypercarbia are clinically the earliest signs) of MH go unnoticed, the production of acid is sufficient to overwhelm the neutralizing capacity of the body and the ability of the lungs to excrete carbon dioxide (CO2) and metabolic acidosis arises. The sustained oxygen debt generated from excessive metabolism usually progresses to multi-organ system failure and death from refractory metabolic acidosis, renal failure, hyperkalemia, arrhythmias, heart failure, coagulation abnormalities and cerebral edema. The term abortive MH is used to define those cases where clinical suspicion arises early in the disease and the triggering agent is discontinued before the development of intramuscular acidosis, limiting the metabolic abnormalities and the development of the full clinical picture of MH. Early termination of the anesthetic in the presence of abortive MH may allow spontaneous resolution of the syndrome. In clinical practice many anesthesiologists are inclined to over-diagnose episodes of abortive MH, which has had a dramatic effect in the overall incidence and mortality of the disease. However, MH may present rather acutely and the anesthesiologist in charge should pursue common diagnoses while directing treatment for the rare occurrence of intraoperative fulminant MHC.

Diagnosis and Treatment

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MH should be identified and treated early in order for there to be a successful outcome. Once MH is suspected and all triggering agents have been discontinued, call for help and obtain IV dantrolene sodium as soon as possible. Dantrolene is thought to reduce muscle tone by preventing the ongoing release of calcium storage to the sarcoplasm. Therapy should be initiated by the administration 2.5-4.0 mg/kg of IV dantrolene bolus rapidly, and continued as needed until clinical signs of MH (tachycardia, hypercarbia, rigidity and hyperthermia) are controlled. The treatment of a patient with acute MH is a serious and demanding undertaking and may require the assistance of all the individuals present in the operating suite. Each vial of dantrolene contains 20 mgs of dantrolene and 3 grams of mannitol that require mixing with 60ml of sterile water prior to injection. This makes the mixing and administration of dantrolene a two-person task. Simultaneously, attention should be aimed at the presence and treatment of severe metabolic acidosis, decreased urine output and cardiac dysrhythmias due to acidosis, and hyperkalemia. These conditions often require the immediate administration of bicarbonate, glucose, insulin, antiarhythmics, diuretics, inotropes and pressors to maintain electrolyte balance, adequate urine output and tolerable hemodynamics. Depending on the availability of personnel, arterial access and central venous access may prove to be of tremendous help following the initial management. Non-pharmacologic measures include actively cooling the hyperthermic patient with infusion of IV cold saline, surface cooling with ice and cold saline lavage of stomach, bladder, rectum and open cavities.

If acute MH or abortive MH has occurred, the patient should recover in the ICU for at least 24 hours. Dantrolene once used should be continued and titrated to alleviate hypermetabolism. Suggested dantrolene dosage is at least 1 mg/kg q 4-6 hours for at least 24 hours. Disseminated intravascular coagulopathy may be present while in the ICU, thus monitoring coagulation status is warranted. The presence of myoglobinuria suggests rhabdomyolysis and acute renal failure is a possibility. Maintenance of urine output of at least 2 ml/kg/hr may prevent worsening renal function. Dialysis should be considered in case of refractory metabolic acidosis and hyperkalemia.

In summary, mortality rate from MH has dropped dramatically since first described. Much knowledge has been handed to us from our predecessors in the field of anesthesia, and today we feel somewhat safer from a disease that once had 80percent mortality. However, death from MH is still a possibility, even in today’s falsely expected flawless medical care. Even when recognized promptly and treated correctly, MH can cause multi-organ failure, and ultimately death, in the susceptible individual. So, it is our job to identify and take seriously those patients with any family history of MH susceptibility, to have personnel informed and trained to deal with the possibility of an MH crisis, and be ready to provide our must humble and earnest support to those family members of a patient recovering from acute MH.

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Reducing Blood Stream Infections in the CVICU

Janie Kane, R.N.

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Reducing Blood Stream Infections in the CVICU
By Janie Kane, R.N.; Clinical Nurse Specialist, Arkansas Children’s Hospital.

In the fall of 2006, the Cardiovascular Intensive Care Unit became involved in a nation-wide project aimed at reducing the incidence of blood stream infections (BSI) related to central lines (catheters) in the pediatric ICU population. Patients who have central lines in place are at an increased risk of infection, especially when in an ICU where there are acutely ill patients and increased exposure to infective organisms. If a central line becomes infected, the patient must be treated intravenously with antibiotics, and frequently, the central line must be removed in order to clear the infection. The patient must then have a peripheral IV placed until the infection clears and/or until another central line can be placed. Both are to be avoided: putting the child through peripheral IV placement and likely another central line insertion, and additional exposure to a course of antibiotics. Although the current rate of infection in CVICU is low (2.9 infections per 1,000 catheter days), we are participating in order to further reduce our infection rate as a quality improvement initiative.

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Details of the Project

The project involves sharing of information among project participants in order to establish best practice and track infection rates, both individually and collaboratively. Emphasis is on central line insertions (whether in the operating room or at the bedside) and on daily line maintenance by the RN staff. Every line insertion is observed for compliance with recommended practice, which involves use of proper hand hygiene, sterile technique, skin prep and line dressing. Sites of insertion as well as types of catheters used are tracked. Line maintenance by RN staff also is observed to determine compliance with recommendations, tracking dressing change techniques, tubing changes, and line entries. The use of chlorhexidine for skin prep and line entry (accessing the tubing in order to administer medications, draw blood, etc.) is under scrutiny as possibly a better antiseptic than either betadine or alcohol. As catheter-related blood stream infections occur, data about that catheter insertion and daily maintenance is collected. Caregivers then attempt to determine the likely source of infection and possible ways it could have been prevented. All of this data is submitted to a national database. Each institution receives feedback on its compliance with practice recommendations, and overall infection rates are reported to the entire collaborative.

How the Project has Affected the Heart Center

Our involvement in the project has increased staff awareness of BSI and the impact their care has on patient outcomes, both as individual caregivers and as a team. It also has been of great benefit to share successes and failures with other institutions across the country. Across the board, project participants have been more than willing to share which measures work and which don’t, all in the hope of positively impacting the children under their care. Since the project began in 2006, the overall rate of blood stream infection related to central lines in the participating hospitals’ pediatric ICU population has decreased from approximately 5.4 infections per 1,000 catheter days to approximately 3.2 infections per catheter days. With further work and diligence, we hope to reduce it by 50 percent, if not eliminate it as a source of morbidity for the children for which we care.

Heart Center Staff Sharpen Skills at Conference

Deanna Edwards

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Mari Hanson

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Many members of the nursing staff and several physicians from the Heart Center headed to Orlando in February to attend the 10th Annual Update on Pediatric Cardiovascular Disease. Of those team members, three nurses were selected to present posters to those in attendance. Janie Kane (see picture above) presented on “Nursing Care of the Pediatric VAD Patient”. Deanna Edwards put together a presentation on “Minimizing Errors at Nursing Handover”. Mari Hanson’s poster examined “Compassion Fatigue and Burnout”. All three put many hours and much research into their posters, and each was well received by the crowd in attendance at the update. The Heart Center was proud to be represented by such dedicated nurses.
The conference included live demonstrations of anatomical specimens and review of perioperative care, imaging, intraoperative video and follow-up care for patients with several conditions, including double outlet right ventricle and heterotaxy/isomerism.
The experience was an excellence winter boost for the Heart Center team. It provided a comprehensive update on current research and clinical trials in children’s and babies’ heart disease, as well as a safety-focused review of techniques. Each team member returned to the ACH Heart Center refreshed and ready to help more children!

The Heart Center Beats Along With Many Activities

Since February is the month to consider matters of the heart, it only makes sense that it’s also a busy month for all members of the ACH Heart Center team! From our annual meeting to high-profile recognition for one of our hard-working anesthesiologists, the past month brought many milestones.
            On Feb. 12, many of the ACH staff and invited guests gathered in Chairman’s Hall to mark the Annual Heart Center meeting. The past year’s accomplishments and events were highlighted, which included “The Year in Review”, “Looking Forward”, and presentation of “Heart of Excellence” awards. These awards are presented to those nominated by their peers as outstanding in providing excellent care for our patients. The event proved to be both uplifting and motivational. It was capped by remarks by chief cardiothoracic surgeon Robert D.B. “Jake” Jaquiss, M.D., who spoke about how the level of teamwork in the Heart Center is the key to positive patient outcomes.
            Arkansas Gov. Mike Beebe declared the week of Feb. 7 – Feb. 14, 2007 as Congenital Heart Defects Awareness Week, with Feb. 14 as “A Day for Hearts”. This is becoming a yearly tradition, and many of the family members of past and present ACH with congenital heart conditions attended.
            Finally, the annual Heart Ball was held on Feb.24, 2007. Michael Schmitz, M.D., Chief of Cardiac Anesthesiology at ACH, received the dedication of the Heart Ball Quilt. Each square of the quilt is created by the loving hands of pediatric cardiology patients and reflects the spirit of these young hands. It has become a tradition over the past six years and is the highly anticipated climax to the evening.
            The Heart Center team is proud of the hard work of its staff and their dedication to improving the lives of our patients. Every month of every year is about helping children with congenital heart conditions. February, however, continues to prove itself as a special time in the life of our center.

Spotlight on Shelby Norfleet, Registered Respiratory Therapist

Shelby Norfleet

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What is your role at ACH, and how long have you worked here?
I am a Registered Respiratory Therapist and have worked at ACH for three years.

Why is your job rewarding?
It is rewarding to see a former patient re-visit the unit knowing you played a significant role in that patient’s recovery.

How did you become interested in pediatric cardiology or cardiovascular surgery?
I began my career as a surgical technologist, so it was easy for me to find interest in cardiovascular surgery. That’s when I started wearing my OR caps.

What do you want people to know about the Heart Center at Arkansas Children's Hospital?
It is a challenging, rewarding and fun place to work. The Heart Center kids and their will to overcome the circumstances are proof that miracles live here.

What do you enjoy most about working with children?
Children enjoy living life and appreciate the opportunity to laugh in spite of their pain. Therefore, I enjoy working with them because it reminds me how insignificant my problems are.

What has been your most memorable moment working in the Heart Center at Arkansas Children’s Hospital?
Showing Dr. Jaquiss how to use the Staples “Easy Button”; it could be a great tool back in the OR.

What is your greatest professional achievement?
I’m still working on it. I’ll let everyone know how it turns out.

Spotlight on Maria Bode, R.N., Cardiology Clinic Nurse

Maria Bode, R.N.

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What is your role at ACH, and how long have you worked here?
I am a nurse in the cardiology clinic, and I have worked at ACH for 15 years.

Why is your job rewarding?
I find my job very rewarding because, although it can be very stressful and emotionally difficult, it can take just a smile from a child, or a thank you from anxious parents to make it worthwhile.

How did you become interested in pediatric cardiology or cardiovascular surgery?
I had worked in other areas of the hospital but never cardiology, and it was time for a new challenge.

What do you want people to know about the Heart Center at Arkansas Children's Hospital?
There’s lots but the most important, to me, is that I think the people who work here truly care about the patients and their families who come here, and they want to make a positive difference and impact in their lives.

What do you enjoy most about working with children?
I think that children can have the most positive attitudes (and the best smiles), and you can always count on hearing the unexpected – at least once a day!

What has been your most memorable moment working in the Heart Center at Arkansas Children’s Hospital?
There have been many interesting and memorable moments, but I have to say that my MOST memorable is last Halloween when Dr. Moss and Dr. Frazier saw their clinic patients dressed as penguins, and when all of us “penguins” toured the hospital. It was great to see the smiles on the faces of the patients, families and staff.

What is your greatest professional achievement?
Just being where I am right now, I think, because there has been a succession of personal achievements, small and not so small, to get here. It starts with graduating nursing school and becoming an RN and ranges to leaving my country and family and everything familiar to me to face the unknown by starting work at ACH. I was a new graduate, and deciding to stay here once my contract was up also was important because I think it’s the best hospital of its kind! The people who work here are great, and I’m proud to be part of a special team.