Interpretation in the Congenital Heart. Stephen M. Paridon, MD Medical Director, Exercise Physiology Laboratory The Children s Hospital of Philadelphia Professor of Pediatrics The University of Pennsylvania School of Medicine
Disclosures None.
in the Congenital Heart Limitations of exercise performance in children and adults with congenital heart disease is a consequence of: Cardiovascular physiology. Physician imposition. Societal imposition.
in the Congenital Heart Congenital cardiovascular disease occurs in slightly less than 1% of live births. Most defects a minor and result in no significant cardiac impairment. In those less common cases of serious cardiac defects, surgical techniques developed over the last 50 years have resulted in excellent palliation and cardiac performance in most types of defects.
in the Congenital Heart Therefore, exercise performance is normal in most of the population with a structural heart defect. There remain, however, a sizable and growing population with palliated heart defects that have significant residual abnormalities. These abnormalities are often manifested by limited or unusual response to exercise.
in the Congenital Heart Factors limiting exercise performance in the child or adult with a congenital heart defect are many and varied. Type of defect and nature of the repair Primary or secondary myocardial abnormalities Electrophysiological abnormalities Residual pulmonary abnormalities
Type of defect: Exercise Testing in the Congenital Heart As a rule, the fewer the number of chambers and great arteries - the worse the exercise performance. Even in those hearts with 4 chambers, 4 valves, and 2 great arteries, residual defects are common. Surgical repair is usually not curative.
in the Congenital Heart Preoperative anatomy: preoperative anatomy frequently defines the type and quality of the postoperative repair or palliation (especially in complex lesions). As such, it is often critical in determining post-operative exercise performance.
in the Congenital Heart Important preoperative anatomic factors affecting postoperative exercise performance include: Ability to perform a 2 versus 1 ventricle repair Morphology of the systemic ventricle The development of both the proximal and distal pulmonary vascular bed
in the Congenital Heart Residual postoperative defects are frequently key to determining cardiovascular performance during exercise. Residual ventricular outflow obstruction Leaky valves Residual intracardiac shunting of blood
in the Congenital Heart Myocardial performance: Excessive stresses placed on the myocardium either as consequence of abnormal hemodynamics or peri-operative factors may result in impaired inotropic ability over time. These stresses may occur in-utero, preoperatively, or postoperatively.
in the Congenital Heart Inotropic impairment of the myocardium is often progressive and may result in steady deterioration in exercise performance. This process maybe initiated or accelerated by residual structural abnormalities.
in the Congenital Heart Specific factors associated with impaired myocardial performance include: Chronic volume overload Chronic pressure overload Multiple and/or prolonged periods of cardiopulmonary bypass
Electrophysiology: Exercise Testing in the Congenital Heart Electrophysiological abnormalities may result in impairment of exercise performance by either directly affecting cardiac output or by causing symptoms that result in cessation of exercise.
Types: Exercise Testing in the Congenital Heart Arrhythmias- atrial or ventricular Heart block- congenital or acquired Sinus node disease- resulting in varying degrees of chronotropic impairment
in the Congenital Heart Pulmonary abnormalities: Studies over the last several decades indicate that many palliated congenital heart defects have associated pulmonary abnormalities. It is often unclear if these abnormalities are an integral part of the disease process or are secondary to surgical attempts to palliate the cardiovascular condition.
in the Congenital Heart Both restrictive and obstructive patterns may be seen in resting lung mechanics. Ventilation-perfusion mismatching is common in complex single ventricle physiology. Pulmonary function may limit exercise performance in select cases but is often out weighted by residual cardiac abnormalities.
in the Congenital Heart Within a population with the same class of cardiac defect, various factors may influence the exercise performance of otherwise similar individuals.
These include: Exercise Testing in the Congenital Heart Age at time of repair Lifestyle- including physician and non- physician restrictions on activities Other associated abnormalities (especially when heart disease is part of a syndrome)
in the Congenital Heart Left to their own devices, most pre-adolescent children are pretty good at regulating their own levels of activity. Difficulty in performing exercise testing on young children. Lack of sudden death from sports in this population.
in the Congenital Heart Post adolescents tend to be more of a problem. Higher levels of physical activity. Often, more complex lesions. Desire to do competitive sports.
Exercise Testing: Where. Why. How.
Space- 250 to 500 square feet per testing station. Climate- ventilated, humidity at 50% and temperatures regulated between 20 0 C and 23 0 C.
Equipment: Ergometers ECG Monitor Blood Pressure monitor Pulse oximeter Metabolic Cart Crash cart Exercise Testing
Ergometers. Treadmill Stationary cycle.
ECG monitor: Liquid crystal or cathode ray tube display. QRS complexes, ideally multiple, can be monitored continuously. Ideally, all QRS complexes should be stored, either as a hard copy or digitally. Automated devices are available on many recorders to detect arrhythmias.
Blood pressure monitor: Automated systems designed for exercise testing incorporating a microphone positioned over the brachial artery. Many of these systems receive an ECG signal gating to the QRS complex filtering background noise. Generally measure by both oscillometric and, direct auscultation.
Pulse oximeter: fitted for the finger or ear are used to measure arterial saturation of oxygen. The devices are frequently inaccurate, particularly at high rates of work when children are prone to grasp the cycle handlebars too tightly
Metabolic cart: Measures VO 2, VCO 2, as well as pulmonary functions such as VE, tidal volume, and respiratory rate. These systems frequently perform spirometry, and receive input from other sources, such as an ECG recorder. This allows a single system to generate complete and final reports.
Why.
Why not?
How.
Protocols: Multiple treadmill and cycle protocols are available all have their advantages and disadvantages. The goal should always be to match the best protocol to the question that is being addressed.
Wasserman et.al Principles of Exercise Testing and Physiology, 1999
Thank you.