The cardiopulmonary exercise stress test (CPET) – Ideal for a personalized sports routine, and for assessing complex pathologies
About the cardio-pulmonary system / What is the cardio-pulmonary system
The cardio-pulmonary (or cardio-respiratory) system should be seen as an entity. While the heart and lungs can be divided into their component parts (pulmonary acini, airways for the lungs and atria/ventricles for the heart), it is essential to view these organs as an integrated unit, each influencing the other. To understand this link let us consider the circuit of deoxygenated blood returning from the systemic circulation. This blood enters the right atrium through the venae cavae, then passes into the right ventricle and is pumped into the pulmonary arteries leading to the lungs. These arteries branch into capillaries, just as the main bronchi divide into smaller bronchioles. Gas exchange takes place in the alveoli, where residual carbon dioxide is exchanged for fresh oxygen. The oxygenated blood returns to the heart through the pulmonary veins. The left atrium receives this blood and passes it to the left ventricle, which then pumps it through the systemic circulation. The heart and lungs in turn receive oxygenated blood from the bronchial and coronary arteries.
How your body responds to intense exercise
Maximal exercise capacity refers to the maximal capacity of the cardiovascular system to deliver oxygen to the locomotor system and the maximal capacity of skeletal muscles to extract oxygen from the blood. Consequently, exercise tolerance depends on three factors: pulmonary gas exchange, cardiovascular performance and skeletal muscle metabolism.
Oxygen consumption (VQ2) is related to body weight and expressed in units of ml O2/kg/min. A metabolic equivalent (MET) s equal to the oxygen consumption (VQ2) at rest - sitting position and has a value of 3.5 ml/kg/min. The VQ2 depends on heart rate, stroke volume and oxygen in the arterial and venous systems.
During maximal physical exertion, VQ2 max reflects a person's maximal capacity to take up from the lungs, transport and utilize oxygen. VQ2 max defines an individual's functional aerobic capacity. The VQ2 max has become the most important element in cardiorespiratory testing, especially in fitness centers and is the most important measurement during functional exercise testing. In healthy humans after the peak VQ2 max is reached, a plateau appears indicating the level of maximal aerobic effort. This peak represents the maximum level of oxidative metabolism that can be attained for an individual using most large muscle groups. However, in clinical tests, this plateau cannot always be reached, as physical activity is often limited by various symptoms that occur unexpectedly. Consequently, the highest attained VO2 (PVO2) is often used as an estimate of VO2 max.
Cardiopulmonary or cardiorespiratory exercise testing (CPET)
What is CPET
The cardiopulmonary exercise stress test (CPET) assesses the basic function of this system and its compensatory mechanisms during physiological stress, exemplifying the relationship between structure and function.
The cardiopulmonary exercise stress test (CPET) is a non-invasive method that assesses and integrates the response of the respiratory, cardiovascular (CV) and musculoskeletal systems to exercise. It is considered the gold standard in the assessment of cardiorespiratory function and is extremely useful in the differential diagnosis of exercise intolerance. The cardiopulmonary exercise stress test (CPET) should be seen as more than just a diagnostic element, as it has an essential role in risk stratification, prognostication and therapeutic assessment in different clinical settings, in the recommendation of exercise, both in patients in need of cardiovascular or pulmonary rehabilitation, as well as in healthy athletes aiming to improve their performance.
Why exercise testing is rarely used
Despite being recommended by several scientific societies in a wide range of recommendations, cardiopulmonary exercise testing (CPET) is still underutilized for multiple reasons such as:
- its complexity
- lack of trained staff to interpret it
- lack of awareness of the need for it
- its availability
- relatively high costs
In which situations is exercise testing recommended
- Athlete evaluation:
- detecting various heart diseases, especially in high-performance athletes
- in assessing basic functional capacity
- in the assessment of sporting ability, especially in recreational sports
- when assessing performance after different training modalities
- Cardiac Recovery
- Ischemic heart disease
- Cardiomyopathy
- Heart failure
- Optimizing exercise capacity in rehabilitation (recovery) programs
- Identifying other overlapping causes that would unexplained worsen patients' symptoms (dyspnea) or exercise capacity
- Various valvopathies
- early identification of unreported symptoms
- identifying the mechanism of dyspnea
- establishing the prognosis to help identify the right time for surgery
- Pulmonary hypertension
- Congenital heart disease
- Dyspnea of unidentified cause
- Miscellaneous lung diseases
- assesses effort capacity and level of disability
- provides useful information to support a diagnosis
- assess hypoxemia during exercise and underlying mechanisms, defining therapeutic strategies (such as pulmonary rehabilitation)
- pre-operative assessment of the risk of complications in lung surgery and provision of prognostic information
In asymptomatic athletes, cardiopulmonary exercise testing (CPET) is important for:
In addition, it plays an important role in identifying overtraining and preventing overtraining syndrome.
Important for exercise risk stratification, for the type of exercise allowed, for the duration of recommended exercise - the cardiopulmonary exercise test (CPET) is the gold standard for recommending aerobic exercise in various situations encountered in daily practice.
Even though imaging modalities are the standard of diagnosis of ischemic heart disease, cardiopulmonary exercise testing (CPET) provides valuable information about the contribution of ischemia to physical intolerance. It has an important role in the prognosis of these patients.
The cardiopulmonary exercise stress test (CPET) is a safe and useful tool in the evaluation of patients with suspected/confirmed hypertrophic cardiomyopathy (HCM) providing information about symptoms, disease severity, prognosis and to plan or monitor therapeutic efficacy. Information obtained by cardiopulmonary exercise stress testing (CPET) can be integrated with data from other investigations for the differential diagnosis between athlete's heart and cardiomyopathies. Although the application of cardiopulmonary exercise testing (CPET) in arrhythmogenic cardiomyopathies is rare, it has been shown to be reliable and potentially useful for risk stratification when considering advanced therapies (such as cardiac transplantation).
Cardiopulmonary exercise stress testing (CPET) is recommended as part of the evaluation for heart transplantation and/or mechanical circulatory support with class I indication.
Two other recommendations would be:
In valvular heart disease, cardiopulmonary exercise testing (CPET) has a role in:
When evaluating a patient with an established or suspected diagnosis of pulmonary hypertension (PH), cardiopulmonary exercise stress testing (CPET) may be useful for identifying the pathophysiologic mechanism of exercise intolerance, assessing the severity of PH, quantifying response to treatment, and stratifying mortality risk.
The cardiopulmonary exercise stress test (CPET) is safe to perform in a broad spectrum of congenital heart disease, not only for risk stratification, but also for deciding on percutaneous or surgical intervention, as well as recommending exercise and training.
Dyspnea experienced during physical exertion or activities of daily living may be an early symptom of various cardio-pulmonary or neuromuscular diseases, which could implicitly lead to self-limitation of activity, resulting in muscle deconditioning and decreased quality of life. Dyspnea is a predictor of quality of life, exercise tolerance and predictor of mortality in several pathologies, (it is superior to FEV1 in COPD and superior to angina pectoris in ischemic heart disease).
The cardiopulmonary exercise stress test (CPET) is extremely useful in assessing patients with lung disease:
In which situations exercise testing is NOT recommended
- Acute Coronary Syndrome
- Uncontrolled arrhythmias causing hemodynamic symptoms or instability
- Pancarditis (endocarditis, myocarditis, pericarditis - active)
- Severe aortic stenosis
- Decompensated heart failure
- Any other acute, decompensated, unstable, life-threatening or life-threatening medical condition that would render the cardiopulmonary exercise test (CPET) irrelevant
How often side effects occur in exercise stress testing:
- Incidence of a complication requiring hospitalization ≤2 in 1000
- Incidence of major cardiac event < 1.2 per 10 000
- Mortality incidence of 2-5 per 100 000
What side effects may occur:
- The risk of side effects is the same as the risk assumed for light exercise
- The number of patients developing complications during cardiopulmonary exercise testing (CPET) is low
- Complications may include abnormal blood pressure changes, syncope or cardiac arrhythmias
- Serious complications are extremely rare, such as heart attack or stroke
How the stress test works
Taking the test
The cardiopulmonary exercise test (CPET) can be performed on a treadmill or on a bicycle.
The exercise treadmill is more commonly used in cardiology laboratories and offers the advantage of allowing exercise that is more representative of the daily activities of most individuals: walking, jogging and running and is thus often well tolerated by most patients. These types of exercise also involve the upper body musculature due to the overall nature of the movement; the effect of this is that VO2 max can often be 5%-10% higher than a cardiopulmonary exercise test (CPET) performed on a bicycle. This is an obvious advantage in the assessment of athletes or those patients where determination of VO2 max is desirable. The disadvantage of involving upper body musculature would be the higher likelihood of motion artifacts, i.e. in measuring parameters such as blood pressure, oximetry, ventilation and influencing gas exchange indicators.
The cycle ergometer is an alternative to the exercise treadmill. These devices are physically smaller and usually less expensive than most treadmills. Exercise on a cycle ergometer is well tolerated by most individuals, but can be difficult for those who are new to cycling or for those individuals who have real orthopedic problems or obliterative arteriopathy (the latter two limitations also apply to the treadmill test).
The cycle ergometer is often considered a safer option than the treadmill for patients with balance or gait problems. On a cycle ergometer, the patient can stop pedaling as soon as they can no longer continue the test, whereas those exercising on a motorized treadmill must first signal to the operator that they wish to stop before the treadmill is slowed to a stop. In the obese patient, use of the cycle ergometer may offer an advantage. Often obese individuals who are unable to run on a treadmill can conduct a bicycle exercise test for a sufficient period of time to generate enough data for analysis.
The cycle ergometer is particularly useful when testing elderly or frail patients who require much milder increases in exercise intensity than younger or fitter individuals. The obvious disadvantage of the cycloergometer is that VO2 max is going to be lower compared to treadmill testing; the advantage is the pragmatism with which the test is performed, the low noise, the ease with which patients/subjects can be monitored - such as measuring BP or performing ECG, or blood gas sampling or oxygen saturation analysis.
| Bicycle | Treadmill | |
| Maximum oxygen consumption | Inferior | Higher |
| Ability to adapt protocol ramp | Easier | Harder |
| Quantifiable physical effort | Yes | Algorithm based |
| Collecting blood gas | Easier | Harder |
| ECG quality | Higher | Lower |
| Noise and artifacts | Less | More |
| Safety | Safer | Risk of falling down |
| Ease for obese patients | Easier | Harder |
| Subject's training level | Lower | Higher |
| Can be used lying down | Yes | No |
| Better suited for | Patients | Athletes |
| Patients with cardiac pacemaker | Rarely recommended | Recommended |
| Cost | Lower | Higher |
| Appliance size | Smaller | Bigger |
| Ease of movement | Easier | Harder |
In which situations the test may finish faster than expected:
- angina pectoris:
- Significant arrhythmias causing symptoms or hemodynamic instability
- Decrease in systolic blood pressure >20 mm Hg from the highest value during the test
- Hypertension >250 mm Hg systolic BP and >120 mm Hg diastolic BP
- Severe desaturation: SpO2 <80% (lower may be acceptable in patients with known underlying lung disease or congenital heart disease
- Loss of movement coordination
- Mental confusion
- Dizziness or lipo/ syncope
Situations related to the patient's condition:
- Dyspnea
- Leg fatigue
- Leg fatigue
- Physical pain/discomfort
- Dizziness
- Discomfort caused by the saddle on a cycle ergometer
- Palpitations
Situations related to reaching maximum effort:
- VO2 max flat on the tracking curve (indicating that the patient has reached the individual VO2 max level)
- Heart rate reaches 90% of the estimated individual heart rate or heart rate reserve is ≤15 beats/min
- There is evidence of ventilation limitation (respiratory reserve <15%, expiratory flow limitation, significant increase in expiratory reserve lung volume)
- mBorg ≥9/10 for leg fatigue or dyspnea
- maximum exercise blood lactate concentration ≥8 mmol/L (if measured)
How to prepare for the stress test
- Refrain from exercise on test day and get plenty of rest
- Eat a light meal or breakfast at least 2 hours beforehand
- Hydration through water only
- Avoid caffeine and alcohol before testing
- Inform your doctor what medication you are taking and decide with him what not to stop before the test
- Bring with you all the medicines you use in case of decompensation or in case of an emergency, e.g. inhalers or medication sprays
- Wear light, comfortable clothing and shoes suitable for exercise
- Avoid using body lotion on the upper part of the body as this may affect ECG recording and electrode placement
- Refrain from smoking at least 8 hours before the test
- Avoid wearing nail polish or false nails
The first step to a healthy heart and optimal physical performance! Visit CorePrime clinic and schedule your cardiopulmonary exercise test (CPET). Throughout the test you will benefit from close and personalized monitoring by two medical professionals, a cardiologist and a pulmonologist. For more details and appointments call +40743999909.
If you are curious about the CPET process, visit our Instagram profile, where you can watch Sorin Voicescu (link), TA doctor and athlete and Simona Hapciuc (link), personal trainer, participating in the cardiopulmonary exercise test.
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