Clinical Challenge: Periodic Breathing in Cardiopulmonary Exercise Testing
Key findings
- A recently published clinical challenge for cardiologists and pulmonologists presents a case that includes graphical representations of cardiopulmonary exercise test results
- The authors invite readers to discern the pattern depicted in the graphs and state the implications of the pattern and its underlying physiologic mechanisms
- The answers to the challenge are given in this summary along with information on the clinical reasoning used and the patient's prognosis
A clinical challenge for cardiologists and pulmonologists was recently presented in the Annals of the American Thoracic Society by Gregory D. Lewis, MD, section head of the Heart Failure and Transplantation Program, the Jeffrey and Mary Ellen Jay chair in Heart Failure, and director of the Cardiopulmonary Exercise Testing Laboratory at Massachusetts General Hospital, and colleagues.
Subscribe to the latest updates from Cardiovascular Advances in Motion
This summary explains the answer to the challenge along with information on the clinical reasoning used and the patient's prognosis.
Case Description
The case concerns a 54-year-old man who reports a one-year history of exertional dyspnea and fatigue with accompanying palpitations, orthopnea and paroxysmal nocturnal dyspnea with overall poor sleep.
He denies chest pain or pressure, syncope, cough and wheezing. His medical history is remarkable only for untreated hypertension, daily alcohol use and being a current smoker of over 20 pack-years.
Based on examination findings the patient is diagnosed with dilated, nonischemic cardiomyopathy with New York Heart Association class III symptoms. He is referred for cardiopulmonary exercise testing (CPET) to assess his exercise capacity and to inform prognostication.
The results are markedly abnormal: peak oxygen uptake of 0.81 L/min (11.0 mL/kg/min, 33% of predicted maximum), indicating severe aerobic impairment.
The authors provide graphs of CPET responses that show near-sinusoidal, oscillatory patterns of ventilatory equivalents, end-tidal oxygen and end-tidal carbon dioxide, rather than the normal linear rise. In addition, the patient's heart rate increased only minimally with increasing work. What are these patterns and their implications?
Clinical Solution and Reasoning
The patient's breathing pattern is clearly periodic. The presence of periodic breathing with a crescendo–decrescendo pattern, without interposed apnea, is consistent with exercise oscillatory ventilation (EOV). No definition of EOV is universally accepted, but all proposed definitions require the presence of regular cyclic variations (oscillations) in minute ventilation during exercise.
Longer cycle lengths reflect greater circulatory time with greater impairment in cardiac output during exercise.
This form of periodic breathing during exercise is termed EOV, whereas when periodic breathing occurs during sleep it is termed central sleep apnea and when it arises during rest with apnea periods it is termed Cheyne-Stokes respiration. When this patient was referred for in-lab polysomnography, the results showed severe central sleep apnea syndrome.
The minimal change in heart rate suggests chronotropic incompetence typical of a patient with heart failure with reduced ejection fraction (HFrEF) and is independent of the EOV.
Prognosis
The presence of EOV has been linked to poorer functional status and a very high risk of adverse outcomes. Most studies have been done in patients with HFrEF and EOV, who have higher mortality rates independent of peak oxygen uptake or NYHA functional class. Hence this pattern frames the appropriateness of considering advanced heart failure interventions such as left ventricular assist device support or heart transplantation in patients with HFrEF and EOV.
EOV is also associated with a more advanced stage of HF, independent of left ventricular function.
view original journal article Subscription may be required
Learn more about the Heart Failure and Transplantation Program
Refer a patient to the Corrigan Minehan Heart Center