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Patent foramen ovale is not a benign pathology in patients undergoing off-pump coronary artery bypass: A word of caution

      To the Editor:
      Author have nothing to disclose with regard to commercial support.
      We thank Bozinovski and Caton
      • Bozinovski J.
      • Caton B.W.
      A benign PFO in OPCAB can suddenly take a right turn, but maybe it can't tolerate it.
      for their valuable article entitled “A Benign PFO in OPCAB Can Suddenly Take a Right Turn, but Maybe It Can't Tolerate It.” They present a case with desaturation due to right-to-left shunt through a patent foramen ovale (PFO) during off-pump coronary artery bypass (OPCAB). Although rare, this is an extremely important problem in the OPCAB procedure. PFO is a frequent pathology with an estimated prevalence of 25%.
      • Kedia G.
      • Tobis J.
      • Lee M.S.
      Patent foramen ovale: clinical manifestations and treatment.
      However, in cases without a known PFO, intermittent intra-atrial shunting due to an elevated right atrial pressure may be an important problem during OPCAB. Because most patients undergoing off-pump revascularization are high risk in terms of chronic obstructive pulmonary disease and elevated pulmonary artery pressures, opening of a PFO is not infrequent when the right atrial pressure increases. This is particularly evident in cases with left and posterior wall revascularization due to positioning of the heart leading to right atrial compression. These patients are not always capable of tolerating decreases in systemic oxygenation and cyanosis due to right-to-left shunting.
      In our practice, we routinely take precautions for securing the right atrium. These are extensive opening of the right pleura and intentional rightward luxation of the heart, opening the pericardial reflection over the superior venae cavae, and leaving the right pericardial stay sutures free while performing the anastomosis on the circumflex and distal right coronary artery target vessels. A second and more important measure is continuous monitoring of the interatrial septum with transesophageal echocardiography during the positioning of the heart. Right atrial distention due to intravenous fluid replacement and external compression of the heart may easily lead to intermittent right-to-left shunting during the procedure, which may lead to cyanosis, even to paradoxical embolization from right to left. In practice, because transthoracic echocardiography is less sensitive than transesophageal examination, it is not always possible to detect a PFO during routine preoperative evaluation. Therefore, we think these simple precautions should be considered in all cases with OPCAB to prevent untoward effects of a right-to-left shunting, such as hypoxemia and systemic paradoxical embolization.

      References

        • Bozinovski J.
        • Caton B.W.
        A benign PFO in OPCAB can suddenly take a right turn, but maybe it can't tolerate it.
        J Thorac Cardiovasc Surg. 2016; 152: e23-e24
        • Kedia G.
        • Tobis J.
        • Lee M.S.
        Patent foramen ovale: clinical manifestations and treatment.
        Rev Cardiovasc Med. 2008; 9: 168-173

      Linked Article

      • A benign patent foramen ovale in off-pump coronary artery bypass can suddenly take a right turn, but can it be tolerated?
        The Journal of Thoracic and Cardiovascular SurgeryVol. 152Issue 1
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          Morita and colleagues1 describe a case of desaturation due to right-to-left shunting through a patent foramen ovale (PFO) when manipulating the heart during off-pump coronary artery bypass (OPCAB). They describe a clinical scenario that, although rare, should be considered when encountering hypoxemia during OPCAB. Neither the prevalence of a PFO nor the incidence of OPCAB is rare, so certainly OPCAB is performed in many patients with a PFO. Presumably in many of these patients the existence of the PFO goes unnoticed, especially when no shunting occurs.
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      • PFO is generally benign in OPCAB: Until it Isn't
        The Journal of Thoracic and Cardiovascular SurgeryVol. 152Issue 2
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          In a letter to the Editor, Drs Ozyuksel and Cetin comment on our editorial commentary1 on an original article by Morita and colleagues.2 To be clear, the former incorrectly credited DrCaton and me with the case presentation rather than Dr Morita and associates, who authored the case report. Drs Ozyuksel and Cetin describe techniques to mitigate cardiopulmonary dysfunction due to positioning during off-pump coronary artery bypass (OPCAB) surgery. I agree that these are worthwhile maneuvers, providing probable benefit at low risk to patients.
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