Page 459 - Cardiac Nursing

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C HAPTER 1 9 / Exercise Testing 435
imaging procedure should be considered. The optimal strategy for tation of the heart to a given amount of submaximal work. 110 This
circumventing false-positive test results in women remains to be slows the delivery of oxygen to the working tissue, contributing to
defined. Nevertheless, the current AHA/ACC guidelines suggest an earlier than normal metabolic acidosis and hyperventilation dur-
that there are insufficient data to justify routine radionuclide im- ing exercise. 108,109,111–113 Although transplantation significantly
aging procedures as the initial test for CAD in women. 4 improves the hemodynamic and ventilatory response to exercise,
the transplanted patient still exhibits many of the responses typical
The Elderly of the patient with chronic heart failure. 113 These include height-
ened ventilatory responses attributable to uneven matching of ven-
The prevalence of CAD increases with increasing age, and the ex- tilation to perfusion and an increase in physiologic dead space.
ercise test can be an extremely useful tool for diagnosing CAD in Maximal heart rate is lower in transplant recipients compared with
the elderly. However, exercise testing in the elderly can be prob- normal subjects, which contributes to a reduction in cardiac output
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lematic given their frequently compromised ability to exercise in and peak Vo 2 ; the arteriovenous oxygen difference widens as a com-
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the context of an increased prevalence of CAD. The occurrence of pensatory mechanism.
fatigue and lightheadedness caused by muscle weakness and de- The exercise test in patients who have undergone cardiac trans-
conditioning, vasoregulatory abnormalities, and difficulties with plantation is less a diagnostic and more a functional tool. In the
gait are important concerns in these patients. Thus, a test modal- latter role, it is useful for assessing and modifying therapy in these
ity and protocol should be chosen that provides the highest degree patients, in addition to evaluating the appropriateness of daily ac-
of safety. For instance, cycle ergometry may be more appropriate tivities and return to work. Although rare cases of chest pain as-
for elderly patients who have a residual deficit from a cerebral vas- sociated with accelerated graft atherosclerosis have been reported
cular accident. In addition, the testing protocol should be modi- in transplant recipients, decentralization of the myocardium usu-
fied considering the expected levels of exercise tolerance. More ally eliminates anginal symptoms. Exercise electrocardiography is
gradually incremented protocols, such as the Balke, ramp, or also inadequate in terms of assessing ischemia, as evidenced by its
Naughton, are usually more suitable in the elderly population. low sensitivity (21% or less). 114 Thus, radionuclide testing may be
The elderly are more likely to present with more complex med- more useful for assessing ischemia in these patients.
ication regimens, more comorbidities, and increased prevalence of
aortic stenosis and other valvular diseases, in addition to more se-
vere CAD. For these reasons, the elderly require particularly close
evaluation before clearance for exercise testing, a modified testing SUMMARY
protocol, and particular attention to appropriate endpoints. 4,97
Interpretation of the exercise test in the elderly can also differ Although there have been advances in technologies related to the
significantly from that in younger people. Resting electrocardio- diagnosis of CAD, the numerous applications and widespread
graphic abnormalities, including previous MI, left ventricular hy- availability of the exercise test continue to make it one of the more
pertrophy, and intraventricular conduction delays, may compro- important tools in cardiovascular medicine. The test is increas-
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mise the diagnostic accuracy of the exercise test. Nevertheless, the ingly being supervised by nonphysicians, and the cardiovascular
application of standard ST-segment criteria among elderly sub- nurse’s role has expanded in many centers to include exercise test
jects has been shown to have similar diagnostic characteristics as supervision. Thus, an understanding of proper methodology, con-
in younger subjects. 99 No doubt because of the higher prevalence duct, indications, and the physiology related to exercise testing are
of CAD in the elderly, test sensitivity has even been shown to be increasingly recognized skills. A good understanding of these prin-
comparatively higher among the elderly (84%), although speci- ciples can also assist the nurse in applying the information gained
ficity is somewhat lower when compared with younger popula- from the exercise test to patients with various cardiovascular dis-
tions (70%). 106 Thus, despite several problems posed by elderly eases. In addition to diagnostic and prognostic information, these
subjects that require additional attention, exercise testing is not applications include the assessment of therapy, exercise prescrip-
contraindicated in this group. 4 tion, and helping to guide medical/surgical management decisions
for the patient.
Patients After Cardiac
Transplantation R EFEREN C E S
Over the past two decades, transplantation has become a widely 1. Ashley, E. A., Myers, J., & Froelcher, V. (2000). Exercise testing in clin-
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used and successful treatment option for patients with end-stage ical medicine. The Lancet, 356, 1592–1597.
heart failure. The 1-year survival rate for patients who have un- 2. Marcus, R., Lowe, R., Froelicher, V. F., et al. (1995). The exercise test as
gatekeeper: Limiting access or appropriately directing resources? Chest,
dergone this procedure is now approximately 85%, compared 107, 1442–1446.
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with only 50% to 60% in patients with severe heart failure who 3. American Thoracic Society/American College of Chest Physicians.
receive medical treatment. 107 The hemodynamic response to ex- (2003). Statement on cardiopulmonary exercise testing. American Jour-
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nal of Respiratory and Critical Care Medicine, 167, 211–277.
ercise in patients who have undergone cardiac transplantation has 4. Gibbons, R. J., Balady, G. J., Bricker, J. T., et al. (2002). ACC/AHA
been characterized since the early 1970s. 108–110 Because the heart 2002 guideline update for exercise testing. A report of the ACC/AHA
is denervated, some intriguing hemodynamic responses are ob- Task Force on Practice Guidelines (Committee on Exercise Testing).
served. Orthotopic transplantation removes the nervous system Journal of American College of Cardiology, 40, 1531–1540.
connections to the heart. Thus, the heart is not responsive to the 5. Mehra, M. R., Kobashigawa, J., Starling, R., et al. (2006). Listing crite-
normal actions of the parasympathetic and sympathetic systems. ria for heart transplantation: International Society for Heart and Lung
Transplantation guidelines for the care of cardiac transplant candi-
The absence of vagal tone explains the high resting heart rates in dates—2006. The Journal of Heart and Lung Tansplantation, 25,
these patients (100 to 110 beats/min) and the relatively slow adap- 1024–1042 .