Acute aortic dissection during scuba diving
Acute aortic dissection during scuba diving
RUNNING HEAD: ACUTE AORTIC DISSECTION DURING SCUBA DIVING
ABSTRACT
A 60-year-old man with hypertension and dyslipidemia complained of chest pain upon ascending from a maximum depth of 27 meters while diving. After reaching the shore, his chest pain persisted, and he called an ambulance. When a physician checked him on the doctor’s helicopter, his electrocardiogram (ECG) was normal, and there were no bubbles in his inferior vena cava or heart on a portable ultrasound examination. The physician still suspected that he had acute coronary syndrome instead of decompression illness; therefore, he was transported to our hospital. After arrival at the hospital, standard cardiac echography showed a flap in the ascending aorta. Immediate enhanced computed tomography revealed Stanford type A aortic dissection. The patient obtained a survival outcome after emergency surgery. To our knowledge, this is the first reported case of aortic dissection potentially associated with scuba diving. It highlights the importance of considering aortic dissection in patients with sudden-onset chest pain during physical activity. In addition, this serves as a reminder that symptoms during scuba diving are not always related to decompression. This report also suggests the usefulness of on-site ultrasound for the differential diagnosis of decompression sickness from endogenous diseases that induce chest pain. Further clinical studies of this management approach are warranted.
Keywords: aortic dissection; scuba diving; ultrasound
Key points
This is the first reported case of aortic dissection potentially associated with scuba diving.
It highlights the importance of considering aortic dissection in patients with sudden-onset chest pain during physical activity. In addition, it serves as a reminder that symptoms during scuba diving are not always related to decompression.
This report also suggests the usefulness of on-site ultrasound for the differential diagnosis of decompression sickness from endogenous diseases that induce chest pain.
INTRODUCTION
Aortic dissection is an emerging medical condition that generally affects the elderly, characterized by the separation of the layers of the aortic wall and the subsequent creation of a pseudolumen that can compress the true aortic lumen.[1] Predisposing factors mediate their risk by increasing the wall tension or causing structural degeneration1 and include hypertension, atherosclerosis, and several connective tissue diseases.[1] If it goes undetected, aortic dissection can carry a significant mortality risk; therefore, a high degree of clinical suspicion and prompt diagnosis is required to maximize survival.[1]
Scuba diving has rarely been associated with spontaneous arterial dissection, and all reported cases affect the cardiac cervicocranial arteries. [2-7] The underlying mechanism in these cases is currently unclear. To date, no cases of aortic dissection related to scuba diving have been reported. We herein report the first case of acute aortic dissection during scuba diving.
CASE REPORT
A 60-year-old man with hypertension and dyslipidemia complained of chest pain upon ascending from a maximum depth of 27 meters while diving. After reaching the shore, his chest pain persisted, and he called an ambulance. The fire department initially suspected that he had decompression sickness, so a doctor helicopter was called.[8] When a physician checked him on the doctor’s helicopter, his electrocardiogram (ECG) was normal, and there were no bubbles in his inferior vena cava or heart on a portable ultrasound examination. The physician nevertheless suspected acute coronary syndrome rather than decompression illness, so the patient was transported to our hospital, which was only equipped with a monoplace chamber.
On arrival, his vital signs were as follows: consciousness, clear; systolic blood pressure, 110 mmHg; heart rate, 97 beats/min; respiratory rate, 22 breaths/min; saturated oxygen, 97% under room air; and body temperature, 37.2°C. His ECG showed no ST changes. However, cardiac echography showed a flap in the ascending aorta. Immediate enhanced computed tomography (CT) revealed Stanford type A aortic dissection without any gas in the vasculature (Figure 1). As the operating rooms were fully occupied with emergency operations at the time, he was transferred to another hospital. He obtained a survival outcome after emergency surgery.
DISCUSSION
To our knowledge, this is the first reported case of aortic dissection potentially associated with scuba diving.
The physical stress associated with scuba diving was likely a trigger for aortic dissection in our case. Intense physical activity is believed to provoke a Valsalva-like increase in intrathoracoabdominal pressure, which can be transmitted to the aortic wall as shear stress.[2] A likely contributing mechanism is a surge in catecholamines that leads to increased arterial contractility or vasospasm, a subsequent increase in aortic shear stress, and, ultimately, intimal rupture or disruption of the aortic wall.[2] This latter mechanism is also the likely mechanism underlying cases of aortic dissection linked to intense emotional stress.[2] Furthermore, diving exposes the cardiovascular system to stressors such as hydrostatic pressure, hyperoxia-induced vasoconstriction, and elevated cardiac filling pressures.[2] Cold and exercise can further amplify these effects, along with increased sympathetic nervous system activity.[2] Importantly, during descent, symptoms at the beginning of the dive result in decompression.
This report suggests the potential utility of on-site ultrasound in the differential diagnosis of chest pain. In the present case, different diagnoses of decompression sickness, air embolism from pulmonary barotrauma, endogenous acute coronary syndrome, and aortic dissection were necessary. The mechanism underlying acute coronary syndrome induced by decompression sickness or air embolism is intravascular gas produced by abrupt decompression or barotrauma.[9] Even in asymptomatic divers, gas bubbles can be detected using ultrasound immediately after diving. Meanwhile, the present case had no air bubbles on ultrasound at the scene or subsequent CT. The physicians on board the Eastern Shizuoka helicopter routinely use ultrasound to make a differential diagnosis on the scene to decide which hospital the diver would be transported to, depending on the availability of recompression facilities. [10,11] If the present case had first undergone recompression therapy, the patient might have died during treatment. However, the use of this device in the differential diagnosis has not been validated in the literature. More clinical studies of this management approach are warranted.
CONCLUSION
To our knowledge, this is the first reported case of aortic dissection potentially associated with scuba diving. It highlights the importance of considering aortic dissection in patients with sudden-onset chest pain during physical activity. In addition, it serves as a reminder that symptoms during scuba diving are not always related to decompression.
This report also suggests the usefulness of on-site ultrasound for the differential diagnosis of decompression sickness from endogenous diseases that induce chest pain. Further clinical studies of this management approach are warranted.
Conflict of Interest Statement
The authors declare that they have no conflicts of interest.
Source of support
This work was partly supported by a Grant-in-Aid for Special Research in Subsidies for Ordinary expenses of private schools from The Promotion and Mutual Aid Corporation for Private Schools of Japan.
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Figure legends
Figure 1. Enhanced computed tomography (CT) on arrival. CT revealed Stanford type A aortic dissection (triangle).