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Pediatric Valvar Aortic Stenosis Workup

  • Author: Howard S Weber, MD, FSCAI; Chief Editor: Steven R Neish, MD, SM  more...
 
Updated: Aug 19, 2015
 

Approach Considerations

In neonates within 24 hours after birth, pulse oximetry is now routinely performed as a predischarge screening to rule out congenital heart disease and measured preductally (right arm) and postductally (lower extremity). Oxygen saturation may be lower in the legs (postductal circulation) because of right-to-left shunting at the level of the ductus arteriosus if patent.

The evaluation for sepsis in infants presenting with shock includes blood, urine, and cerebrospinal fluid (CSF) cultures.

Echocardiography is the diagnostic procedure of choice in all ages. In certain circumstances, exercise stress testing, cardiac catheterization, or both may be indicated.

Go to Imaging in Aortic Stenosis for more complete information on this topic.

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Echocardiography

In the neonate, transthoracic echocardiography usually provides complete diagnostic and hemodynamic information. Essential considerations are the details of valve anatomy, anulus size, distribution of valve tissue, degree of left ventricular hypertrophy, and left ventricular systolic function. The presence or absence of associated lesions, such as mitral valve disease, coarctation of the aorta or subaortic stenosis, can also be well delineated.

Patients presenting with critical aortic valve obstruction and poor left ventricular systolic function may have echodense endocardium typical of endocardial fibroelastosis. Variable degrees of left ventricular hypoplasia or dilation may also be noted. These findings usually indicate that the severe obstruction was present for a significant amount of time prenatally.

In older patients, transthoracic echocardiography is usually diagnostic; in rare cases, however, a large adolescent patient may require transesophageal echocardiography to clearly delineate the left ventricular outflow tract and to detail the valve anatomy. Three-dimensional echocardiography may better delineate the aortic valve anatomy in hopes of determining whether balloon valvuloplasty versus surgical intervention would be more effective.

Doppler echocardiography is used to estimate the severity of aortic valve stenosis noninvasively. The peak instantaneous systolic gradient often overestimates the transvalvular peak-to-peak gradient obtained during cardiac catheterization. Mean Doppler gradients correlate well with peak to peak gradients measured during cardiac catheterization.

In neonatal critical aortic valve stenosis with poor left ventricular systolic function and low cardiac output, the Doppler-derived peak instantaneous gradient may be low and is therefore not indicative of the severity of obstruction.

Exercise stress testing and echocardiography

Exercise stress testing can usually be performed in children aged 6 years or older with aortic stenosis and may elicit symptoms that may not be evident by routine history. Resting Doppler gradients can be helpful in determining whether exercise restrictions are necessary[3] .

Exercise stress testing may also provide risk stratification if intervention is being contemplated. Factors such as heart rate, blood pressure response to exercise (blunted), exercise duration (reduced), provocable arrhythmias (ventricular ectopy of left ventricular origin) or ECG ischemic changes, and measured oxygen consumption provide useful data on which to base decisions whether intervention is necessary.

Stress echocardiography is useful in delineating the response of the left ventricle to increasing afterload during exercise. The exercise stress test findings establish a baseline against which to compare subsequent study results, especially if the patient's symptoms change, the Doppler-derived gradient worsens or in the evaluation of the effectiveness following an intervention.

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Chest Radiography

Chest radiography may reveal cardiomegaly with pulmonary venous congestion, primarily in neonates who present with critical stenosis and symptoms of heart failure. Otherwise, this test is not helpful in asymptomatic patients although aortic root dilation may be identified.

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Cardiac Catheterization

Cardiac catheterization is usually performed in infants, children, and older adolescents with aortic stenosis in anticipation of balloon aortic valvuloplasty. Occasionally, the peak systolic gradient measured in the catheterization laboratory with the patient under conscious sedation is significantly less than that estimated by Doppler echocardiography, and this should be taken into consideration regarding whether intervention is indicated.

Other indications for catheterization may include the need to evaluate left ventricular filling pressures (impaired diastolic function secondary to left ventricular hypertrophy) and for accurate hemodynamic assessment in patients with multiple levels of obstruction, such as mitral stenosis or subaortic stenosis in combination with aortic valve stenosis. In the latter instance, high-fidelity catheters capable of discriminating between multiple levels of obstruction in close proximity are probably preferable but are significantly more difficult to use, especially in young patients.

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Electrocardiography

ECG is not especially useful in neonates or young children with significant aortic valve disease. In older patients, it may reveal left ventricular hypertrophy with or without a strain pattern.

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Magnetic Resonance Imaging

Compared with echocardiography, MRI is rarely used to assess the details of aortic valve anatomy and is much more difficult to use in neonates, who have faster heart rates and more motion artifacts. Obtaining an MRI of infants and young children may require sedation, which carries risk of sudden death and, therefore, should be undertaken with close supervision and administered by an experienced anesthesiologist. New developments in gated MRI for assessing ventricular function may make MRI increasingly useful in adult patients.

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Histologic Findings

In the presence of significant obstruction from aortic stenosis, the left ventricular myocardium hypertrophies concentrically. Critically ill neonates may have extensive endocardial fibroelastosis, especially in the presence of a dilated nonhypertrophied left ventricle. Patients with chronic aortic stenosis and significantly elevated left ventricular systolic pressure may exhibit fibrotic changes in the myocardium.

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Contributor Information and Disclosures
Author

Howard S Weber, MD, FSCAI Professor of Pediatrics, Section of Pediatric Cardiology, Pennsylvania State University College of Medicine; Director of Interventional Pediatric Cardiology, Penn State Hershey Children's Hospital

Howard S Weber, MD, FSCAI is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, Society for Cardiovascular Angiography and Interventions

Disclosure: Received income in an amount equal to or greater than $250 from: St. Jude Medical.

Coauthor(s)

Paul M Seib, MD Associate Professor of Pediatrics, University of Arkansas for Medical Sciences; Medical Director, Cardiac Catheterization Laboratory, Co-Medical Director, Cardiovascular Intensive Care Unit, Arkansas Children's Hospital

Paul M Seib, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, American Heart Association, Arkansas Medical Society, International Society for Heart and Lung Transplantation, Society for Cardiovascular Angiography and Interventions

Disclosure: Nothing to disclose.

Specialty Editor Board

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

John W Moore, MD, MPH Professor of Clinical Pediatrics, Section of Pediatic Cardiology, Department of Pediatrics, University of California San Diego School of Medicine; Director of Cardiology, Rady Children's Hospital

John W Moore, MD, MPH is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, Society for Cardiovascular Angiography and Interventions

Disclosure: Nothing to disclose.

Chief Editor

Steven R Neish, MD, SM Director of Pediatric Cardiology Fellowship Program, Associate Professor, Department of Pediatrics, Baylor College of Medicine

Steven R Neish, MD, SM is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, American Heart Association

Disclosure: Nothing to disclose.

Additional Contributors

Juan Carlos Alejos, MD Clinical Professor, Department of Pediatrics, Division of Cardiology, University of California, Los Angeles, David Geffen School of Medicine

Juan Carlos Alejos, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, American Heart Association, American Medical Association, International Society for Heart and Lung Transplantation

Disclosure: Received honoraria from Actelion for speaking and teaching.

References
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  5. McElhinney DB, Lacro RV, Gauvreau K, O'Brien CM, Yaroglu Kazanci S, Vogel M, et al. Dilation of the ascending aorta after balloon valvuloplasty for aortic stenosis during infancy and childhood. Am J Cardiol. 2012 Sep 1. 110(5):702-8. [Medline].

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  7. Alekyan BG, Petrosyan YS, Coulson JD, Danilov YY, Vinokurov AV. Right subscapular artery catheterization for balloon valvuloplasty of critical aortic stenosis in infants. Am J Cardiol. 1995 Nov 15. 76(14):1049-52. [Medline].

  8. Fischer DR, Ettedgui JA, Park SC, Siewers RD, del Nido PJ. Carotid artery approach for balloon dilation of aortic valve stenosis in the neonate: a preliminary report. J Am Coll Cardiol. 1990 Jun. 15(7):1633-6. [Medline].

  9. Weber HS, Mart CR, Myers JL. Transcarotid balloon valvuloplasty for critical aortic valve stenosis at the bedside via continuous transesophageal echocardiographic guidance. Catheter Cardiovasc Interv. 2000 Jul. 50(3):326-9. [Medline].

  10. Turley K, Bove EL, Amato JJ, Iannettoni M, Yeh J, Cotroneo JV, et al. Neonatal aortic stenosis. J Thorac Cardiovasc Surg. 1990 Apr. 99(4):679-83; discussion 683-4. [Medline].

  11. McCrindle BW, Blackstone EH, Williams WG, Sittiwangkul R, Spray TL, Azakie A, et al. Are outcomes of surgical versus transcatheter balloon valvotomy equivalent in neonatal critical aortic stenosis?. Circulation. 2001 Sep 18. 104(12 Suppl 1):I152-8. [Medline].

  12. Siddiqui J, Brizard CP, Galati JC, Iyengar AJ, Hutchinson D, Konstantinov IE. Surgical valvotomy and repair for neonatal and infant congenital aortic stenosis achieves better results than interventional catheterization. J Am Coll Cardiol. 2013 Dec 3. 62(22):2134-40. [Medline].

 
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Valvular calcification of aortic stenosis seen with cardiac fluoroscopy during catheterization.
 
 
 
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