The Heart Center - Arkansas Children's Hospital

Brian K. Eble, M.D.; Arkansas Children’s Hospital; Assistant Professor of Pediatric Cardiology, University of Arkansas for Medical Sciences College of Medicine

Most testing performed by pediatric cardiologists, including basic clinical examination, electrocardiography, echocardiography, cardiac catheterization and cardiac magnetic resonance imaging, evaluates the cardiovascular system at rest. The principle of exercise testing, in contrast, is to evaluate the cardiac system, as well as its interactions with the pulmonary and musculoskeletal systems, in a scenario of physical stress. In adult cardiology, the goal of exercise stress testing is primarily to detect disease, specifically coronary artery disease and myocardial ischemia. The goal of stress testing in children, however, is often quite different. Typically, the child’s cardiac disease is already known, and the goal of the stress test is to evaluate the effects of the disease or its treatment on the child’s response to exercise. Additionally, exercise testing may be used to determine the patient’s capacity for physical work and participation in sports.

Prior to testing, it is critical that the child understands the testing procedure and familiarizes himself with the equipment. Patient and parent education begins prior to their arrival on testing day. Typically, the patient is instructed not to consume caffeine or a heavy meal prior to testing. The child should also bring comfortable clothing and shoes in which to perform the exercise test. On arrival at the exercise laboratory, the patient should have the testing procedure explained in terms that he and his parents can easily understand, and informed consent should be obtained. The child can be reassured that the test does not hurt and that he or she may request the test be stopped at any point. The patient should also be given an opportunity to familiarize himself with the exercise equipment, including the ergometer, electrocardiogram leads, blood pressure cuff and breathing apparatus if used. In general, children under 8 to 10 years of age have difficulty completing a maximal stress test.

The ergometer is a machine that measures work performed during exercise. Two types of ergometers are commonly used for pediatric exercise testing: the treadmill and the stationary bicycle. The treadmill has the advantages of familiarity (most children are familiar with walking and running) and the application of more large muscle groups. However, the treadmill can be difficult for smaller children, creates greater noise and movement artifact and is inaccurate in quantifying the patient’s work rate. Advantages of the cycle ergometer include accurate measurement of work performed and diminished artifact in the measurement of blood pressure, gas exchange, electrocardiography and, if needed, echocardiography. In addition, smaller children are often more comfortable on the cycle ergometer.

In a healthy individual, cardiac output may increase up to four to five times normal with exercise. Cardiac stroke volume may increase 40 to 60 percent from baseline; the remainder of this increase in cardiac output is therefore dependent on an appropriate increase in heart rate. This increased output is distributed unequally, however, favoring the exercising muscles, heart and skin. During the exercise stress test, multiple respiratory and hemodynamic measurements are recorded. 1) A continuous electrocardiogram is recorded for accurate assessment of heart rate response to increasing work, the detection and diagnosis of arrhythmias and the assessment of ischemic changes or conduction abnormalities. 2) The blood pressure response to exercise is also an important variable measured during testing, and in cases such as aortic stenosis or coarctation may be the primary variable of interest. Because cardiac output usually increases with exercise, systolic blood pressure also increases. Because of vasodilatation resulting in a drop in systemic vascular resistance, diastolic blood pressure typically remains unchanged during exercise. 3) Oxyhemoglobin saturation is also commonly measured during exercise testing with a pulse oximeter, especially in patients with cyanotic heart disease.

The metabolic cart is used to monitor ventilatory and pulmonary gas exchange responses to exercise by measuring airflow and fractional concentrations of O2 and CO2 in expired air. This permits calculation of respiratory rate, minute ventilation, tidal volume, oxygen uptake (VO2) and carbon dioxide production (VCO2). Common measures of aerobic fitness include oxygen uptake at maximal exercise (VO2max), oxygen uptake at the anaerobic threshold (VO2 at VAT, an approximation of the point at which oxygen demand exceeds oxygen delivery) and O2 pulse. VO2max, VO2 at VAT and O2 pulse provide an index of cardiac reserve that has proven diagnostic and prognostic value in a number of conditions.

Various protocols are available for exercise testing in the pediatric population, using both treadmill and cycle ergometers. The modified Bruce protocol is the most commonly used in pediatrics and is a multistage incremental protocol in which the speed and incline of the treadmill is increased every three minutes. In patients who are unable to perform standard exercise testing (such as very young patients or those in which the motion of exercise would interfere with data collection), pharmacologic stress testing may be performed. Agents that increase myocardial oxygen consumption (dobutamine or isoproterenolol) or agents that cause coronary artery vasodilatation (adenosine or dipyridamole) are typically used in such cases.

Certain patients may require specialized equipment during exercise testing, including echocardiography, nuclear myocardial blood flow imaging and spirometry. All patients undergoing exercise testing should have appropriate safety and resuscitation equipment available, including a cardiac defibrillator, oxygen and suction. Practices regarding physician presence or availability during exercise testing differ between testing centers, however a physician typically is immediately available in case of emergencies.

Specific Pediatric Situations:

A few special situations in pediatric cardiology warrant further discussion.

1) Children and adolescents with chest pain: Chest pain is a common complaint in this age group. Frequently, history and physical examination are adequate to rule out a serious cardiopulmonary etiology. For the rare child with typical anginal chest pain consistently related to exercise, however, exercise testing may be a useful evaluation.

2) Wolff-Parkinson-White syndrome: In patients with WPW, exercise stress testing may be useful in risk stratification for rapid conduction. The disappearance of pre-excitation in a single beat during exercise suggests an accessory pathway which is at low risk for rapid conduction of atrial fibrillation and therefore sudden death.

3) Tetralogy of Fallot: Patients with Tetralogy of Fallot who undergo successful surgical repair in the current era have near normal physical working capacity and aerobic capacity. The degree and duration of pulmonary insufficiency and subsequent right ventricular dilatation are key factors in determining aerobic capacity in these patients, while some degree of residual pulmonary stenosis and right ventricular hypertrophy / restrictive physiology have correlated with improved exercise capacity.

4) Functional single ventricle following Fontan palliation: Patients following a Fontan operation have uniformly diminished aerobic capacity. This may be related to impaired chronotropic response to exercise, limited ability to augment stroke volume and abnormal pulmonary mechanics. Routine serial exercise testing in this population may assist in recognizing arrhythmias, the need for pacemaker placement or the need for surgical revision. Additionally, a formal cardiac rehabilitation program has been shown to significantly improve exercise capacity in these patients.

5) Coarctation of the aorta: Following surgical or transcatheter therapy for coarctation of the aorta, exercise testing with pre- and post-ductal blood pressure measurement may reveal residual gradients that are not noted at rest. The clinical significance of these residual gradients with exercise, especially in the absence of systemic hypertension, is debatable.

6) Post-operative coronary artery reimplantation: Patients who undergo coronary artery reimplantation, usually for d-transposition of the great arteries (d-TGA) during an arterial switch procedure or for anomalous left coronary artery from the pulmonary artery (ALCAPA) during coronary reimplantation, are at risk for development of coronary artery insufficiency presumably related to ostial stenosis. Serial exercise testing in this population may prove to be an important screening tool. These patients typically have normal exercise and aerobic capacity, with a relatively high incidence of electrocardiographic abnormalities of unclear clinical significance.

7) Following Kawasaki disease with coronary involvement. Patients with coronary artery aneurysms typically demonstrate normal aerobic capacity, although the incidence of abnormal radionuclide imaging and electrocardiographic findings is relatively high. Again, the clinical significance of these findings is debatable.

In conclusion, exercise stress testing is a safe and important adjunct to the management of many child and adolescent patients with congenital and acquired heart disease. This modality provides the clinician with information about the performance of the cardiovascular and pulmonary systems under metabolic stress. This information is critical in the current era of low operative mortality in which attention has increasingly turned toward improving morbidity and quality of life for our patients.

Paridon SM, Alpert, BS, Boas SR, et al. Clinical Stress Testing in the Pediatric Age Group, A Statement from the American Heart Association Council on Cardiovascular Disease in the Young, Committee on Atherosclerosis, Hypertension, and Obesity in Youth. Circulation. 2006;113:1905-1920.

Driscoll DJ. Exercise Testing in Allen HD, Gutgesell HP, Clark EB, Driscoll DJ, eds. Moss and Adams’ Heart Disease in Infants, Children, and Adolescents, including the Fetus and Young Adult, 6th edition. Baltimore, MD. Lippincott Williams & Wilkins. 2000: 264-275.

Gibbons RJ, Balady GJ, Bricker JT, et al. ACC/AHA 2002 guideline update for exercise testing: summary article: a report of the American College of Cardiology / American Heart Associated Task Force on Practice Guidelines. Circulation 2002;106:1883-1892.

Paridon SM. Exercise Testing in Garson A, Bricker JT, Fisher DJ, Neish SR eds. The Science and Practice of Pediatric Cardiology, 2nd edition. Baltimore, MD. Williams & Wilkins. 1998: 875-888.

Rhodes J, Curran TJ, Camil L, et al. Impact of cardiac rehabilitation on the on the exercise function of children with serious congenital heart disease. Pediatrics 2005;116:1339-1345.

Wernovsky G, Rome JJ, Tabbutt S, et al. Guidelines for the outpatient management of complex congenital heart disease. Congenital Heart Disease. 2006;1:10-26.

Diller GP, Dimopoulos K, Okonko D, et al. Exercise intolerance in adult congenital heart disease comparative severity, correlates, and prognostic implication. Circulation. 2005;112:828-835.

Chang RKR, Gurvitz M, Rodriguez S. Current practices of exercise stress testing among pediatric cardiology and pulmonology centers in the United States. Pediatric Cardiology. 2006;27:110-116.

Gatzoulis MA, Clark AL, Cullen S. Right ventricular diastolic dysfunction 15 to 35 years after repair of tetralogy of Fallot: restrictive physiology predicts superior exercise performance. Circulation 1995;91:1775-1781.

Charles E. Johnson, R.N., C.C.P.;Chief of Pediatric Perfusion; Manager, CTOR, Pediatric and Congenital Cardiac Surgery, Arkansas Children’s Hospital, University of Arkansas for Medical Sciences

Current success with the palliation of single ventricle pathology has resulted in a greater number of patients who are likely to achieve Fontan candidacy (1,2). This is the result of accurate diagnosis, surgical innovations, cardiopulmonary bypass strategy, ICU management and pharmacological advances. Fenestration, modifications to the hydrodynamics of the connections, and the bidirectional cavopulmonary connection as a stepping stone towards achieving Fontan candidacy has allowed a smoother transition towards the Fontan completion (2,3). Currently, most institutions have documented improved survival for Fontan completion in both children and adults (1,2,3).

However, the Fontan circuit remains an unnatural physiological state with well-documented multiple deleterious end organ effects (1,4). In addition, the myocardial substrate is often far from ideal and is further compromised by re-operation, chronic hypoxemia, volume and pressure overload, as well as electrophysiology issues. The longevity of the Fontan is thus limited, and under conditions of a so-called “perfect” Fontan, there is a steady attrition rate with the 15-year survival at 73% (1,7).

Unfortunately, pushing the limits or extending the boundaries of those patients to whom a Fontan is offered only further increases the likelihood of a poor candidate presenting for transplant. With an accepted rate of failure for the procedure and increasing Fontan candidacy in the face of a critical donor shortage, we have over time created a problem that will continue to escalate. Fontan revision is unfortunately available only to a select few.

There are misconceptions about the Fontan operation with many physicians regarding the Fontan as a biological bridge to transplant. Unfortunately, the use of a transplant as a bailout procedure at any time along a single ventricle pathway is fraught with hazards and bad outcomes. The criteria for a failing and failed Fontan are nebulous at best (5), and the risk of death while waiting for transplant as a Status I candidate is significantly higher than a Status II candidate in the Fontan state (10).

Fontan failure induces multi-organ dysfunction, which complicates preoperative stabilization, intraoperative management, and postoperative survival. This includes protein losing enteropathy, plastic bronchitis, and the presence of aortopulmonary collaterals, previously created surgical shunts, systemic venous collaterals and pulmonary arteriovenous malformations (1,3,4).

Cardiac transplant in a patient with multiple previous surgeries, and highly abnormal anatomy, can be a formidable task. Accurate pre-transplant assessment is mandatory. Cardiac catheterization remains the cornerstone for pre-transplant evaluation and interventional techniques are invaluable to optimize subsequent surgery. MRI and rapid sequence CT scanning have recently provided us with a three-dimensional tool that can accurately predict the requirements for the transplant as well as the hazards encountered with sternal reentry. A careful scan of the vascular access is also mandatory so that emergency cannulation, as well as venous and arterial access sites are safely used and spared. Pre- transplant mechanical support has been described, requiring imaginative and unconventional techniques.

The transplant is often lengthy, predisposing the patient to complications related to increased exposure of cardiopulmonary bypass, longer donor ischemic times, and often-unrecognized residual lesions such as distal pulmonary artery stenoses, proximal intrapulmonary venous obstruction and lack of vascular access. Sternal and chest wall abnormalities contribute to further limit exposure. Cardiopulmonary bypass is tailored to the specific anatomic and physiological constraints imposed by the previous surgical interventions and/or underlying anatomy. The potential for right ventricular failure is omnipresent in these patients, mandating perfect donors and organ over-sizing (1,3,9)

Patients with congenital heart disease remain at a higher risk for mortality after transplantation and patients who have had a previous Fontan are at even higher risk with hospital mortality rates from 33 to 67 percent (1). The poor results of transplant in this cohort are multifactorial, and attrition of survivors results in approximately 50 percent alive at six years (7,8,10). Fontan3

Conclusion: Cardiac transplantation is the only option for patients who present with an end-stage Fontan. Early and late mortality remain high in these patients, and morbidity is not insignificant. Objective parameters for Fontan failure are needed so as to accurately predict which patients would benefit most from earlier intervention, either revision or transplant, so as to optimize post transplant survival.

1. Mitchell MB, et al: Heart transplantation for the failing Fontan circulation: Sem
     Thorac Cardiovasc Surg: Ped Card Surg Ann; 56-64, 2004
2.   Fontan F, et al: Outcome after a “perfect” Fontan operation. Circulation 81: 1520-
     1536, 1990
3. Michielon G, et all: Orthotopic heart transplantation for congenital heart disease:
     An alternative for high-risk Fontan candidates? Circulation 108 (suppl 1): II140-
     II149, 2003

4. Marjan Jahangiri, et al; Coagulation factor abnormalities after the Fontan procedure
     and its modifications: J Thorac Cardiovasc Surg 113 (6): 989-93, 1997
5. Cheung YF, et al: Serial assessment of left ventricular diastolic function after Fontan
     procedure. Heart 83: 420-424, 2000
7. Hsu DT, et al: Heart transplantation in children with congenital heart disease. J
     Am Coll Cardiol 26:743-749, 1995
8. Lamour, JM, et al: Outcome after orthotopic cardiac transplantation in adults with
     congenital heart disease. Circulation 100:II200-II205, 1999
9. Michielon G, et al: Orthotopic heart transplantation for failing single ventricle
     physiology. Eur J Cardiothorac Surg 24: 502-510, 2003
10. Bernstein D, et al: Outcome of listing for cardiac transplantation for failed Fontan.
     24th Annual ISHLT Meeting, April 21-24, 2004

A Privilege...Care of the Newborn From Diagnosis Through Norwood Stage-One Palliation for Hypoplastic Left Heart Syndrome

Sherry Pye, MNSc, APN, CCRN; Advanced Practice Nurse, Cardiology, Arkansas Children’s Hospital

Eighteen years ago, providing nursing care for the newborn with a diagnosis of Hypoplastic Left Heart Syndrome was disheartening and sad for the pediatric critical care nurse. The survival of newborns after Norwood stage-one palliation was marked with significant morbidity and mortality. Since that time, technological advances and improvement in diagnostic techniques, pre-operative, intra-operative and post-operative care, and a better understanding of medical problems in the convalescent period, has demonstrated improved survival rates. (1,2) Over the past ten years, the pediatric critical care nurse has had to adapt to the specific needs of these newborns and their families.

Congenital Heart Defect:
Hypoplastic Left Heart Syndrome (HLHS) is defined as a spectrum of congenital cardiac anomalies associated with the underdevelopment of left-sided heart structures. Common features (Fig. 1) include aortic valve atresia, hypoplasia of the ascending aorta, hypoplasia of the aortic arch and hypoplastic or absent left ventricle.3

Fig. 1
At birth, blood flow to the body is dependent on the patency of the ductus arteriosus. Early diagnosis and initiation of prostaglandin E1 (PGE1) therapy to keep the ductus arteriosus open is key to promote optimal cardiac output and end organ perfusion.

Pre-operative Care:
Upon diagnosis of HLHS, PGE1 therapy should be initiated and the newborn admitted into the Intensive Care Unit (ICU) with stabilization as the main objective. The critical care nurse will focus on airway and breathing, because apnea is an associated risk of PGE1 administration. Monitoring of oxygenation and ventilation occurs through the use of blood gas analysis, pulse oximetry and end tidal CO2. Cardiac output will be optimized through the use of inotropic support. Parental nutrition will be used to provide calories needed for growth and the increased metabolic state of heart failure. A pre-operative head and renal ultrasound will be performed for surveillance of other possible congenital anomalies that may be present and impact on post-operative recovery.
The critical care nurse will establish rapport with the family in order to become a familiar face as the family travels the long road of recovery with their newborn. Open communication between the medical staff and parents is important to alleviate their stress and fears. Parental participation in their newborn’s care is encouraged from admission to discharge.

Surgical Procedure:
The surgical approach for HLHS occurs in planned stages. Stage-one palliation is a modified Norwood with pulmonary blood flow provided through either a modified Blalock-Taussig shunt (Fig. 2) or a right ventricle to pulmonary artery conduit (Fig. 3).

Fig. 2 Fig. 3

Post-Operative Care:
            Providing post-operative care to the newborn after undergoing stage-one palliation is challenging for the critical care nurse. Upon returning from the operating room (OR), the focus is on airway, breathing and circulation. A secure airway and support of breathing is provided through mechanical ventilation. Maintaining a balanced Qp:Qs relationship is the goal when monitoring and manipulating oxygenation and ventilation. Oxygen saturation goals are 75 to 85 percent. Special nursing precautions such as pre-oxygenation and sedation are undertaken when the newborn is suctioned in the first 24 hours to prevent a pulmonary hypertensive crisis and instability. Clinical assessment of circulation is followed through trends of cardiac output markers such as near infrared spectroscopy (NIRS), lactate levels, perfusion, urine output and other end organ parameters. Delivery of inotropic support to achieve optimal cardiac output is of high importance in the immediate post-operative phase.
            The newborn may return from the OR with his/her chest open. Indications for leaving the chest open include hemodynamic instability, respiratory compromise, bleeding, myocardial edema and dysrhythmias. (4,5) The newborn will undergo delayed chest closure after hemodynamic stability has been achieved and maintained. Precise measurements of intake and output are maintained to prevent fluid overload and generalized edema. Renal function is monitored and urine output is encouraged through the use of diuretics and supplemented as needed with peritoneal dialysis. Electrolytes are replaced as warranted.
            Pain control and sedation are provided in the form of infusions. Additional analgesia and sedation are administered by the critical care nurse as indicated by clinical assessment. Controlling pain and agitation in the early post-operative phase of recovery helps to decrease the cardiac output demand. Activities of daily living, such as range of motion, turning, oral care and bathing occur on an ongoing basis at the discretion of the critical care nurse.
            In the recovery phase, each newborn advances at his/her own individual pace. After hemodynamic stability has been achieved and delayed chest closure undertaken, the ventilator is weaned to extubation. After extubation, the newborn may require extra support in the form of CPAP to prevent fatigue and atelectlasis. Progression to room air occurs with close monitoring of pulse oximetry and respiratory effort.
            The final hurtle in the recovery process is nutritional support and feeding. Parental nutrition is provided early post-operatively. Trophic enteral feeds of breast milk or the formula of parent’s choice are initiated via a nasogastric tube (NGT) or transpyloric tube (TPT) once hemodynamic stability is achieved. The feeds are then transitioned to full enteral feeds as tolerated. Prior to starting oral feeding, the newborn must be evaluated for vocal cord function, the presence of aspiration and the presence of gastroesophageal reflux (GER). (6) An Occupational Therapist or Speech Therapist is consulted to help with promotion of normal oral motor skills and bottle feeding. When vocal cord dysfunction is detected with the presence of aspiration and/or GER, an alternate form of enteral feeding should be selected, such as a surgical gastrostomy tube with/without a Nissen fundoplication.

Discharge Preparation:
By this point in time, the newborn has been in the ICU setting a minimum of two to three weeks. The family is excited but scared at the prospect of going home. The critical care nurse is very valuable in the discharge preparation and teaching. Teaching items include, but are not limited to, the following: arranging home health nursing, occupational, speech and/or physical therapy; teaching medication administration and formula mixing; obtaining the home supplies needed for different routes of feeding; arranging for home monitoring of pulse oximetry and weight; teaching incisional care with signs and symptoms of complications; arranging parental CPR training and encouraging normal newborn care. Newborn immunizations, hearing screen and state- mandated screens are completed prior to discharge.
One can now visualize the long, intense journey that the pediatric critical care nurse travels with these special newborns. It is a privilege.

1. Cua, C. L., Thiagarajan, R. R., Gauvreau, K., Lai, L., Costello, J. M., et al. Early
    postoperative outcomes in a series of infants with hypoplastic left heart syndrome
    undergoing stage I palliation operation with either modified Blalock-Taussig shunt or
    right ventricle to pulmonary artery conduit. Pediatric Critical Care Medicine.
    2006;7(2):1-7.

2. Nelson, D. P. Paying more attention to morbidity in infants with hypoplastic left heart
     syndrome. Pediatric Critical Care Medicine. 2005;6(5):614-615.

3. Nichols, D. G., Cameron, D. E., Greeley, W. J., Lappe, D. G., Ungerleider, R. M., &
     Wetzel, R. C. Critical Heart Disease in Infants and Children. St. Louis: Mosby; 1995:
     863-884.

4. McElhinney, D. B., Reddy, V. M., Parry, A. J., Johnson, L., Fineman, J. R., & Hanley,
     F. L. Management and outcomes of delayed sternal closure after cardiac surgery in
     neonates and infants. Critical Care Medicine. 2000;28(4):1180-1184.

5. Elami, A., Permut, L. C., Laks, H., Drinkwater, D. C., & Sebastian, J. L. Cardiac
decompression after operation for congenital heart disease in infancy. The Society
of Thoracic Surgeons. 1994;58:1392-6.

6. Skinner, M. L., Halstead, L. A., Rubinstein, C. S., Atz, A. M., et al.
Laryngopharyngeal dysfunction after the Norwood procedure. The Journal of
Thoracic and Cardiovascular Surgery. 2005;130(5):1293-1301.

Long QT Syndrome

Liz Shira, RN, BSN; Electrophysiology Specialty Nurse, Department of Pediatric Cardiology, University of Arkansas for Medical Sciences, Arkansas Children’s Hospital

A recent ABC News story focused on Long QT Syndrome and its tragic effect on the Shockley family. Casey, the 16-year-old daughter of Bill and Linda Shockley, was a healthy, active teenager who, at the start of a typical day, died suddenly as a response to an alarm clock. This mystery was unraveled as an electrocardiogram performed earlier demonstrated a prolonged QT interval that unfortunately was diagnosed too late as Long QT Syndrome (LQTS). Further genetic testing confirmed that this young girl and other members of her family had the inherited gene causing LQTS.

LQTS may be to blame for more than half the sudden, unexplained deaths in teenagers and young adults. It is estimated that LQTS affects approximately one in 5,000 people in the United States. With increasing public awareness of sudden cardiac death, as well as advancements in the diagnosis of the genetic causes of LQTS, we are able to identify and treat more individuals than ever before and offer more reassurance and protection from sudden cardiac death.

LQTS defines a group of ion-channel diseases affecting the action potential of the cell membrane of cardiac tissue. LQTS is characterized on the electrocardiogram as a prolonged QT interval. The prolonged QT interval can potentially result in torsade de pointes degenerating to fatal arrhythmias. LQTS can result from either acquired causes, such as medications, or genetic mutations of the gene encoding specific cardiac ion channels. LQTS is manifested clinically as seizure disorder, syncope or sudden death. Individuals with LQTS are often times asymptomatic and experience their first symptom as sudden arrhythmia death. Thus, identifying individuals at risk for LQTS becomes paramount in providing appropriate treatment to reduce the risk of syncope and sudden death.

Diagnosing Long QT Syndrome
The assessment of LQTS is the first tool for diagnosing individuals for LQTS. The patient’s symptoms are important to document along with any history of seizure disorder, syncopal events or palpitations. Associating these symptoms with activities and emotions is relevant in the diagnosis. Also, identifying any external causes such as medications, electrolyte imbalances or other medical conditions that can affect the QT interval is necessary. The family history is pivotal in assessing for LQTS. It is important to identify any family members who experienced an unexplained sudden death, drowning, seizure disorder or syncope.

Several tests are useful in the diagnosis of LQTS. Electrocardiograms are a “window” into the patient’s QT interval and refractoriness of the heart. Corrected QT intervals (QTc) are calculated carefully, taking into consideration sinus arrhythmia and rate variability. A QTc measuring 440 milliseconds or greater indicates a prolonged QT interval. Additionally, certain T-wave changes and morphologies can be indicative of certain types of LQTS. In patients who are able to exercise, an exercise test is utilized to determine the QT response to exercise and recovery. Individuals with LQTS exhibit prolonging QT intervals with exercise. Echocardiograms are useful in identifying any structural or functional changes that might cause prolonged QT intervals. Newer tests offering insight into certain types of LQTS are chemical drug challenges. Epinephrine and procainamide are two vasoactive drugs given as an intravenous infusion that cause ECG changes specific to certain genetic types of LQTS and Brugada Syndrome.

Genotype testing is another useful tool for diagnosing LQTS. Until 2004, genetic testing was performed primarily in research laboratories. It was not uncommon for results to take years to process, thus affecting the ability to identify the genetic cause of LQT and offer appropriate and timely treatment options. Now, we employ the use of commercial genotype testing to evaluate for a possibility of one of the five genotypes involving the sodium and potassium channels. Commercial genetic testing provides results within six to eight weeks, allowing for more prompt identification and appropriate treatment for LQTS. One of the benefits of commercial genotype testing is the ability to identify family members who may be asymptomatic but genotype positive for LQTS. When an individual has a positive genotype for LQTS, it is recommended that family members likewise be tested for the genotype. Genotype testing must not be used alone to diagnose and treat LQTS. Each facet of testing must be utilized and evaluated together to diagnose LQTS.

Acquired Long QT Syndrome
Acquired Long QT Syndrome is the result of certain external factors affecting the QT interval. These include medications, electrolyte imbalances, and other medical conditions such as thyroid disease. It is important to distinguish between inherited LQTS and acquired LQTS when determining treatment approaches. In acquired LQTS, treatment is aimed at correcting the underlying cause. Many prescribed and over the counter medications prolong the QT interval. It is essential to identify those medications before prescribing to those patients with acquired LQTS or inherited LQTS. The Arizona Center for Education and Research on Therapeutics (www.qtdrugs.org) provides an up to date list of medications known to prolong the QT interval. Commonly prescribed medications included on this list are Ritalin, Concerta, Adderall, Strattera, Elavil, Cipro, Erythromycin, Zithromax and Propulsid.

Treatment Options for Long QT Syndrome
Treatment for inherited LQTS is determined by identified genotypes, patient symptoms and family history. The potassium channelopathies (LQT1 and LQT2) are responsive to beta-blocker therapy, whereas the sodium channelopathies (LQT3, Brugada Syndrome) are responsive to mexilitine. Implanted cardiac defibrillators are indicated in patients with or without known genotypes, who are symptomatic or have a strong family history of sudden death.
Certain triggers are associated with LQTS. These include: Patient

Intense physical activity (e.g., swimming, running, competitive sports)
Strong emotions (crying, stressful situations)
Noises that startle (doorbell, phone ringing, alarm clock)
Sleep (most common in LQT3)

Recommendations for lifestyle modifications to account for these triggers are also part of the management plan. The goal of treatment of LQTS is prevention of sudden cardiac death.

The Heart Center at Arkansas Children’s Hospital has become a regional leader in the diagnosis and treatment of Long QT Syndrome and other causes of sudden cardiac death. We employ state of the art diagnostic capability along with current recommended treatment and management plans.

The Heart Center at Arkansas Children’s Hospital recently brought two staff members into new leadership roles. They will be working alongside other Heart Center members to provide care, love and hope to all their patients and families.

Janie Kane, R.N., M.S., is the new clinical nurse specialist for the Heart Center. She began her career in the CVICU at ACH before moving to attend graduate school at Boston University. She remained in Boston, where she was employed at Children’s Hospital for 18 years. She returned to Arkansas in 2003 to be closer to family. Upon her return, Janie worked in the Heart Center as a staff nurse on the weekend shift.

As a clinical nurse specialist, Janie assists the nursing staff through education and consultation. She enjoys spending time at the bedside, facilitating the improvement of patient care through evidence-based nursing. Janie is active in research and supports the staff with on-going projects. She also prepares and presents material for publication and presentation.

Cynthia Pye, R.N., Cynthia Pye, R.N., is the new clinical instructor for the Heart Center. Of her 10 years of nursing experience, 6 have been at ACH. She began as a traveler in the Heart Center before joining the staff as a full-time employee. She has contributed to the department as an ECMO technician, and in 2004, she received the Children’s Heart Center Heart of Excellence Award.

Cindy’s primary responsibility is to develop, coordinate and facilitate educational opportunities for the Heart Center staff. Her roles include orientation and competency assurance for new staff members, as well as on-going education and performance improvement for existing staff. Cindy collaborates with hospital leadership and Heart Center staff to ensure continued delivery of high quality patient- and family-centered care.