Miranda WR, Jain CC, Borlaug BA, Connolly HM, Egbe AC.J Heart Lung Transplant. 2022 Jun;41(6):704-707. doi: 10.1016/j.healun.2022.02.023. Epub 2022 Mar 9.PMID: 35400586
Take Home Points:
- In the vast majority of patients with a Fontan circulation, the exercise capacity is significantly reduced due to a multitude of reasons, including impaired stroke volume augmentation, chronotropic incompetence, abnormal oxygen extraction by the muscles, lung disease and others.
- While obtaining resting hemodynamics in patients with a Fontan circulation is informative and can be helpful in guiding clinical decision making, it provides little information on patient’s hemodynamics during exercise.
- In this small study, the investigators describe their experience with four exercise hemodynamic studies obtained in patients with a Fontan circulation using supine bicycle. Three of these patients were referred for heart transplantation evaluation and the fourth for assessment of a Fontan pathway obstruction.
Commentary from Dr. Yonatan Buber (Seattle, USA), section editor of ACHD Journal Watch:
Table: Clinical and hemodynamic data of the 4 study patients
The authors describe how in each of the cases, the invasively measured hemodynamics assisted in the clinical decision making: in Case 1, a case that was used I a combination with echo, it revealed increase in the wedge pressures due to severe systemic AV valve stenosis and the patient underwent a valvular intervention, in Case 2 it revealed significant diastolic dysfunction and elevation in the wedge pressures, and the patient was referred for a transplant evaluation, in Case 3, no marked abnormalities were found and the patients was referred to a rehab program and prescribed with a PDE-5 inhibitor with marked symptomatic improvement, and in Case 4, a significant increase in the IVC pressures was observed, indicating hemodynamically significant obstruction in the IVC limb, and stenting was undertaken with resolution of the gradient.
Invasive exercise hemodynamics in patients with a Fontan circulation provides an excellent method to evaluate the degree and the potential contributors to exercise intolerance, which as noted above is common in this patient population and may often be multi-factorial. In this brief and very educating communication, the authors provided with three examples of different hemodynamic abnormalities that were almost not apparent at rest and were revealed during exercise, and nicely show how this affected clinical decision making. Importantly, they also provide one example of a relatively benign hemodynamic response to exercise which prompted a referral to cardiac rehabilitation and initiation of a pulmonary vasodilator. No complications were reported in this series.
Future directions include the utility of evaluating the effects of pre-exercise NO administration on exercise hemodynamics in Fontan patients, and the potential utility of less invasive methods such as combined cardio-pulmonary exercise testing with echo +/- non-invasive stroke volume assessment to provide with similar results and clinical implications.