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Impact of phrenic nerve palsy on late Fontan circulation (Commentary)
Journal Pre-proof Impact of phrenic nerve palsy on late Fontan circulation (Commentary) T.-Y. Hsia, MD PII:
S0003-4975(19)31730-8
DOI:
https://doi.org/10.1016/j.athoracsur.2019.09.094
Reference:
ATS 33240
To appear in:
The Annals of Thoracic Surgery
Received Date: 24 September 2019 Accepted Date: 28 September 2019
Please cite this article as: Hsia TY, Impact of phrenic nerve palsy on late Fontan circulation (Commentary), The Annals of Thoracic Surgery (2019), doi: https://doi.org/10.1016/ j.athoracsur.2019.09.094. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 by The Society of Thoracic Surgeons
Impact of phrenic nerve palsy on late Fontan circulation (Commentary)
In the Fontan circulation, variation in the negative intrathoracic pressure associated with normal respiration enhances venous return and pulmonary blood flow. This influence is now well known, with further recognition that phrenic nerve palsy leading to diaphragmatic paralysis is poorly tolerated in Fontan patients. It is rare for a Fontan patient with phrenic nerve palsy to be able to go home without surgical diaphragm plication. However, there is an awareness growing that despite fixing the diaphragm to prevent its paradoxical motion, Fontan patients with phrenic nerve palsy will have more restrictive ventilatory physiology and potentially worse hemodynamics, at least in the short term, than those with normal diaphragmatic function. [1] Since a significant proportion of children with phrenic nerve palsy following congenital heart surgery will eventually recover diaphragm function, the logical questions are what happens to those paralyzed diaphragms in Fontan patients, and how they are coping later in life.
The difficulty with answering these questions, however, is also a blessing: not many Fontan patients had paralyzed diaphragms. Thanks to Komori and colleagues [2] from the highly respected group in Osaka, Japan, we are able to gain valuable insights in this issue of The Annals. In an elegant study that included spirometry, exercise testing, and cardiac catheterization, they delineated some of the long-term effects of phrenic nerve palsy in Fontan patients 10 years after total cavopulmonary connection completion.
Despite the unavoidable imbalance of patient
cohort to the Control group (those who never had phrenic nerve palsy), their findings were quite interesting, and surprising: 1) nearly half of the patients with phrenic nerve palsy recovered diaphragmatic function, and 2) despite worse restrictive ventilatory impairment, those with persistent diaphragmatic paralysis did not have deleterious hemodynamic outcomes or exercise capacity, even when compared with patients who never had diaphragm problems.
These findings are of course contrary to what we have expected. While it may not be surprising that half of the paralyzed diaphragms recovered, the discovery that Fontan patients with persistent phrenic nerve palsy have essentially equivalent hemodynamics and exercise tolerance (such as anaerobic threshold and peak oxygen consumption) as those with normal diaphragm function went against conventional (and unsupported) supposition. One would expect that losing
the valuable respiration driven flow benefits would significantly impact how they cope with the obligatory and unrelenting adversities of the Fontan physiology. Nonetheless, Komori and colleagues’ data suggests that they are indeed coping well. It is worth noting that instead of relying on one single test, such as spirometry alone, the authors were able to engender a more complete picture and gather accurate answers with concomitant cardiac catheterization and cardiopulmonary exercise testing. For complex physiologies such as the Fontan circulation, this study further validates the importance of multi-disciplinary and multi-modality follow up. T-Y Hsia, MD Chief, Pediatric Cardiac Surgery Yale School of Medicine and Yale New Haven Children’s Hospital LLCI 301, 333 Cedar Street New Haven CT 06520-8064 Email: [email protected]
References: 1. Ovroutski S, Alexi-Meskishvili V, Stiller B, et al. Paralysis of the phrenic nerve as a risk factor for suboptimal Fontan hemodynamics: Eur J Cardiothoracic Surg. 2005;27;561565. 2. Komori M, Hoashi T, Shimada M, et al. Impact of phrenic nerve palsy on late Fontan circulation. Ann Thorac Surg 2019.
S0003-4975(19)31730-8
DOI:
https://doi.org/10.1016/j.athoracsur.2019.09.094
Reference:
ATS 33240
To appear in:
The Annals of Thoracic Surgery
Received Date: 24 September 2019 Accepted Date: 28 September 2019
Please cite this article as: Hsia TY, Impact of phrenic nerve palsy on late Fontan circulation (Commentary), The Annals of Thoracic Surgery (2019), doi: https://doi.org/10.1016/ j.athoracsur.2019.09.094. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 by The Society of Thoracic Surgeons
Impact of phrenic nerve palsy on late Fontan circulation (Commentary)
In the Fontan circulation, variation in the negative intrathoracic pressure associated with normal respiration enhances venous return and pulmonary blood flow. This influence is now well known, with further recognition that phrenic nerve palsy leading to diaphragmatic paralysis is poorly tolerated in Fontan patients. It is rare for a Fontan patient with phrenic nerve palsy to be able to go home without surgical diaphragm plication. However, there is an awareness growing that despite fixing the diaphragm to prevent its paradoxical motion, Fontan patients with phrenic nerve palsy will have more restrictive ventilatory physiology and potentially worse hemodynamics, at least in the short term, than those with normal diaphragmatic function. [1] Since a significant proportion of children with phrenic nerve palsy following congenital heart surgery will eventually recover diaphragm function, the logical questions are what happens to those paralyzed diaphragms in Fontan patients, and how they are coping later in life.
The difficulty with answering these questions, however, is also a blessing: not many Fontan patients had paralyzed diaphragms. Thanks to Komori and colleagues [2] from the highly respected group in Osaka, Japan, we are able to gain valuable insights in this issue of The Annals. In an elegant study that included spirometry, exercise testing, and cardiac catheterization, they delineated some of the long-term effects of phrenic nerve palsy in Fontan patients 10 years after total cavopulmonary connection completion.
Despite the unavoidable imbalance of patient
cohort to the Control group (those who never had phrenic nerve palsy), their findings were quite interesting, and surprising: 1) nearly half of the patients with phrenic nerve palsy recovered diaphragmatic function, and 2) despite worse restrictive ventilatory impairment, those with persistent diaphragmatic paralysis did not have deleterious hemodynamic outcomes or exercise capacity, even when compared with patients who never had diaphragm problems.
These findings are of course contrary to what we have expected. While it may not be surprising that half of the paralyzed diaphragms recovered, the discovery that Fontan patients with persistent phrenic nerve palsy have essentially equivalent hemodynamics and exercise tolerance (such as anaerobic threshold and peak oxygen consumption) as those with normal diaphragm function went against conventional (and unsupported) supposition. One would expect that losing
the valuable respiration driven flow benefits would significantly impact how they cope with the obligatory and unrelenting adversities of the Fontan physiology. Nonetheless, Komori and colleagues’ data suggests that they are indeed coping well. It is worth noting that instead of relying on one single test, such as spirometry alone, the authors were able to engender a more complete picture and gather accurate answers with concomitant cardiac catheterization and cardiopulmonary exercise testing. For complex physiologies such as the Fontan circulation, this study further validates the importance of multi-disciplinary and multi-modality follow up. T-Y Hsia, MD Chief, Pediatric Cardiac Surgery Yale School of Medicine and Yale New Haven Children’s Hospital LLCI 301, 333 Cedar Street New Haven CT 06520-8064 Email: [email protected]
References: 1. Ovroutski S, Alexi-Meskishvili V, Stiller B, et al. Paralysis of the phrenic nerve as a risk factor for suboptimal Fontan hemodynamics: Eur J Cardiothoracic Surg. 2005;27;561565. 2. Komori M, Hoashi T, Shimada M, et al. Impact of phrenic nerve palsy on late Fontan circulation. Ann Thorac Surg 2019.