Introduction

The main purpose of the cardiopulmonary exercise testing is to determine an individual's physiological response under exercise stress, and to evaluate their performance in certain specific lifestyle and occupational conditions based on the results. The test mainly quantitatively assesses the following factors: 1) aerobic exercise ability (that is, evaluating the maximum oxygen uptake, V02max); 2) changes in blood flow during exercise (mainly evaluating the response of heart rate and blood pressure); 3) cardiac electrophysiological response during exercise (whether there is arrhythmia or changes in ST segments); 4) signs or symptoms that limit exercise.

Indications

(1) Help in the diagnosis of the cause of exercise limitation

(2) Evaluation of exercise capacity

(3) Assessment of pre-operative cardiopulmonary risk

(4) Evaluation of the effectiveness of surgery or drug treatment

(5) Creation of an "exercise prescription" and exercise training plan

(6) Assessment of the degree of disability

(7) Risk stratification

(8) Assessment of prognosis

Contraindications

• Absolute Contraindications

1. A recent significant change in the resting EGG suggesting infarction or other acute events
2. Recent complicated myocardial infarction
3. Unstable angina
4. Uncontrolled ventricular dysrhythmia
5. Uncontrolled atrial dysrhythmia that compromises cardiac function
6. Third-degree A-V block
7. Acute congestive heart failure
8. Severe aortic stenonsis
9. Suspected or known dissecting aneurysm
10. Active or suspected myocarditis or pericarditis
11. Thrombophlebitis or intracardiac thrombi
12. Recent systemic or pulmonary embolus
13. Acute infection
14. Significant emotional distress (psychosis)

• Relative Contraindications

1. Resting diastolic blood pressure > 120 mm Hg or resting systolic blood pressure > 200 mm Hg
2. Moderate valvular heat disease
3. Known electrolyte abnormalities (hypokalemia, hypomagnesemia)
4. Fixed-rate pacemaker (rarely used)
5. Frequent or complex ventricular ectopy
6. Ventricular aneurysm
7. Cardiomyopathy, including hypertrophic cardiomyopathy
8. Uncontrolled metabolic disease (e.g., diabetes, thyrotoxicosis, or myxedema)
9. Chronic infectious disease (e.g diabetes, thyrotoxicosis. or myxedema)
10. Neuromuscular, musculoskeletal, or rheumatoid disorders that are exacerbated by exercise
11. Advanced or complicated pregnancy

Interpretations

The results of a cardiovascular functional test should be interpreted by considering several factors, including:

•  clinical response (such as symptoms, appearance changes, and physical examination)
• functional capacity evaluation
  • functional aerobic impairment
    • The functional aerobic impairment rate is calculated by dividing the difference between estimated and observed maximum oxygen uptake by the estimated maximum oxygen uptake.
  • heart rate
    • Heart rate should have a linear relationship with oxygen uptake.
  • workload and exercise time
    • Workload and exercise time can be used to evaluate the size of VO2 max.
  • rating of perceived exertion
    • The rating of perceived exertion can be used as a basis for comparison.
• cardiovascular response
  • blood pressure
    • An inadequate blood pressure response is defined as blood pressure not increasing by more than 30mmHg during exercise compared to rest. A decrease in systolic blood pressure by more than 20mmHg during exercise is also considered a low blood pressure response. A rise in diastolic blood pressure by more than 25mmHg during exercise is also considered an abnormal response, suggesting the possibility of coronary artery disease.
  • heart rate response
    • Heart rate response is related to workload and the testing method and content, while maximum heart rate response is mainly related to age.
    • If heart rate does not increase relatively with increased workload, it is called "chronotropic incompetence," which suggests that the subject is prone to cardiac events.
  • recovery period blood pressure
    • The ratio of recovery period systolic blood pressure to maximum systolic blood pressure during exercise should be less than 0.9 and 0.8, respectively, at 1 and 2 minutes after recovery. A high value of this ratio may suggest the presence of coronary artery disease.
• ECG response 

1. ST segment elevation: may be accompanied by abnormal Q waves
2. ST segment depression
3. Post-recovery ST segment depression
4. R-wave amplitude: can be used as a reference index for myocardial hypoxia
5. T-wave changes: exercise-induced T-wave inversion can occur in patients with left ventricular hypertrophy or myocardial disease.
6. U-wave inversion: suggests that the subject may have coronary artery disease; this phenomenon is most clearly seen in V5.
7. Arrhythmias
8. Conduction block during exercise: if left bundle branch block (LBBB) occurs, the change in ST segment can be used as a diagnostic basis, while right bundle branch block (RBBB) does not affect the diagnosis of ST segment changes.

Conclusions

The assessment of a patient's exercise function and the effectiveness of various treatments can be greatly enhanced by performing a cardiopulmonary exercise test, which provides invaluable reference data. The test results can also provide the patient with a safe and effective exercise prescription, as well as be used as a reference for future prognosis. The methods and content of the cardiopulmonary exercise test should be adapted to the patient's ability, rather than the patient adapting to the test requirements, and the test results should not be used as the sole diagnostic tool.