Page 37 - Journal of Special Operations Medicine - Spring 2017

Figure 1 This electrocardiogram was interpreted by the tachycardias, myocarditis, pericarditis, and sympatho-
computer as “normal sinus rhythm. ST elevation consider mimetic use; and in a litany of noncardiac causes. 12
early repolarization, pericarditis or injury.”
ST elevation can be caused by several conditions, in-
cluding benign early repolarization, left ventricular hy-
pertrophy, and pericarditis in Takotsubo syndrome.
13
Nonspecific ST-T changes, ST elevations, and right-
sided precordial lead ST elevation consistent with Bru-
gada syndrome have all been reported in patients with
heat stroke. This may be a reflection of the fact that
14
the sodium channel is sensitive to temperature changes.

The combination of ST elevation and elevated troponin
level in this case suggested that heart catheterization was
indicated. There have been some reports suggesting that
discharged several hours later. He was seen by his pri- ST-T changes in the setting of heat stroke are related
mary care provider a few days later and was returned to to an increase in myocardial oxygen demand and not
full-duty status. an anatomic lesion, which should resolve with cooling
measures, obviating the need for standard invasive in-
terventional procedures. 9
Discussion
In this report, we presented the case of a Soldier with Overuse of testing may lead to false-positive findings.
abnormal ECG findings and an elevated troponin level Military-specific data have demonstrated that testing in
without any abnormal findings on cardiac angiogram. this low-risk, healthy population largely leads to clinical
This case demonstrates that nonischemic causes of tro- irrelevant abnormal findings that rarely change clinical
ponin elevations may occur. management. This case report is similar to the military-
specific data set in that testing is likely not needed in as-
Heat illness is commonly encountered in the military ymptomatic cases and will likely lead to additional, and
setting, although command initiatives have greatly de- possibly unnecessary, challenges in the clinical course.
creased the incidence of major adverse events. It is spec-
trum of disease ranging from a mild to moderate illness Our patient did not meet the definition of heat stroke
in the form of heat exhaustion due to water or salt de- and did not appear to have any risk factors such as drug
pletion, with a temperature below 40°C (104°F), to heat use that would contribute to the elevation of troponin
stroke, which is defined as a temperature higher than levels. It is likely that his condition was secondary to a
40°C and with signs of central nervous dysfunction. combination of exercise and heat-related illness. We are
8
Our patient’s signs and symptoms were consistent with unaware of any other reports of elevated troponin levels
the diagnosis of exertional heat exhaustion. in Soldiers associated with heat injury without evidence
of heat stroke.
Most reports about heat-related injury and biochemi-
cal abnormalities have been specific to heat stroke and Conclusion
include several biochemical abnormalities, including
elevated levels of hepatic transaminases, bilirubin, cre- We present the case of a 20-year-old male Soldier with
atine kinase, lactate, creatinine, or serum urea nitrogen; an ischemic-appearing ECG and elevated troponin lev-
hypernatremia; hyponatremia; hypokalemia; hyperkale- els after a heat injury. These findings were not associ-
mia; hypophosphatemia; hypoglycemia; hyperglycemia; ated with any cardiac lesions in this case.
thrombocytopenia; prolonged prothrombin time or pro-
longed activated thromboplastin time; and elevated tro- Disclosures
ponin levels. 8,9
The authors have nothing to disclose.
Elevated troponin levels have also been demonstrated
after intense exercise and in multiple studies after mara- References
thon running events without evidence of cardiac dys-
function. 8–11 This is thought to be due to exercise-induced 1. Bedno SA, Li Y, Han W, et al. Exertional heat illness among
changes in the cell-wall membrane permeability, leading overweight U.S. Army recruits in basic training. Aviat Space
Environ Med. 2010;81:107–111.
to nonischemic troponin leakage. Troponins can also 2. Smalley B, Janke RM, Cole D. Exertional heat illness in Air
10
be elevated in several nonischemic conditions, such as Force basic military trainees. Mil Med. 2003;168:298–303.

Case Report: Exertional Heat Injury 15