Working Diagnosis:
Swimming-induced pulmonary edema related to severe exercise-induced hypertension

Treatment:
The patient was started on aggressive antihypertensive therapy with a combination of Sacubitril and Valsartan. He was titrated to a maximum tolerable dose that did not cause dizziness at rest.

Outcome:
After titration of his antihypertensive medications, he has been able to compete in three open-water triathlon events without return of symptoms.

Author's Comments:
Swimming Induced Pulmonary Edema (SIPE) is a rare form of heart failure with preserved ejection fraction, most often seen in open-water swimmers in a competitive environment. Though the exact mechanism behind SIPE is yet unknown, it is theorized that the external compressive forces of the water, compounded by tight wetsuit wear, physically squeezes blood towards the core. This is further exacerbated by cold water which causes a peripheral vasoconstrictive response. These factors ultimately culminate into higher pulmonary vascular pressures, resulting in pulmonary edema. Studies of civilians who have been afflicted by SIPE demonstrate that approximately 72% of patients have associated cardiac comorbidities which likely make the circulatory system less resilient to these compressive forces, especially in high-demand athletic events.

The diagnosis of SIPE is made by a combination of dyspnea or hemoptysis during or immediately following swimming, without an obvious primary cause (infection, laryngospasm, or water aspiration). The diagnosis is further confirmed by oxygen saturation less than 92%, as well as pulmonary opacities on chest radiography, which should resolve within 48 hours.

All athletes will experience a transient increase in their blood pressure with exercise due to the increased demand of oxygen by muscles, though this is typically offset by vasodilation. In athletes with Exercise-Induced Hypertension (EIH), there is a significant increase in the levels of angiotensin II with exercise, exacerbated by decreased nitrous oxide and increased sympathetic tone. The diagnosis of EIH can be made with systolic blood pressure above 190 in females and 210 in males during exercise testing. When pressures rise to such extreme levels as seen in EIH, the heart will often display a ventricular dyskinesis, similar to that seen in Takotsubo cardiomyopathy.

Due to the increases in angiotensin II in athletes with EIH, first-line treatment should be targeted at the dysfunctional renin-angiotensin-aldosterone system, as was the case with this patient.

Editor's Comments:
SIPE, also known as immersion pulmonary edema, may be seen in swimmers or triathletes (as in this case) as well as SCUBA divers. Pathophysiologic mechanisms suggest that fluid accumulates in the lungs as a result of peripheral vasoconstriction and central redistribution of intravascular volume in the setting of airway pressure differentials. While generally considered a form of noncardiogenic pulmonary edema, underlying heart disease or hypertension can predispose to this condition given baseline increases in pulmonary capillary pressures.

Recent studies report variable incidences of SIPE ranging from 0.44% in a large cohort of open-water swimmers to 5% of US Navy SEAL candidates. Incidence may be higher in women and older individuals. Clinical presentation is similar to more typical forms of pulmonary edema and may not be accompanied by hypoxia. Treatment is usually conservative and symptoms are often self-limited, though some individuals may experience recurrence and warrant treatment of underlying risk factors as seen here.

References:
Hardstedt M, Kristiansson L, Seiler C, Braman Eriksson A, Sundh J. Incidence of swimming-induced pulmonary edema: a cohort study based on 47,600 open-water swimming distances. Chest 2021;160(5):1789-98.

Mohammed LLM, Dhavale M, Abdelaal MK, Alam ABMN, Blazin T, et al. Exercise-induced hypertension in healthy individuals and athletes: is it an alarming sign? Cureus 2020;12(12):e11988.

Peacher DF, Martina SD, Otteni CE, Wester TE, Potter JF, Moon RE. Immersion pulmonary edema and comorbidities: case series and updated review. Med Sci Sports Exerc 2015;47(6):1128-34.

Volk C, Spiro J, Boswell G, Lindholm P, Schwartz J, et al. Incidence and impact of swimming-induced pulmonary edema on Navy SEAL candidates. Chest 2021;159(5):1934-41.

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