Cardiac Structure and Function in Well-Healed Burn Survivors

Abstract

Long-term burn survivors have reduced aerobic capacity, placing them at increased risk for cardiovascular disease, morbidity, and mortality. However, the exact mechanism contributing to a reduced aerobic capacity remains incompletely understood, but may be related to adverse cardiovascular remodeling. Therefore, it was hypothesized that well-healed burn survivors would exhibit adverse left ventricular (LV) remodeling and impaired LV function. To test this hypothesis, 22 well-healed moderately burned individuals (age: 41 ± 14 years; BMI: 27.7 ± 5.4 kg/m2; male/female: 12/10; extent of burn: 37 ± 12 %BSA), 11 well-healed severely burned individuals (age: 43 ± 12 years; BMI: 29.5 ± 5.8 kg/m2; male/female: 8/3; extent of burn: 73 ± 11 %BSA), and 12 healthy, age-matched controls (age: 34 ± 9 years; BMI: 28.6 ± 5.2 kg/m2; male/female: 5/7) were enrolled in the study. All subjects were sedentary, performing less than 30 minutes of aerobic exercise per day, 3 days per week. LV morphology and function were assessed via cardiac magnetic resonance imaging. In contrast to the hypothesis, neither the presence nor severity of burn injury adversely affected LV morphology or function, when compared with equally sedentary nonburned controls. However, of note, LV mass of all three groups was in the lowest 5th percentile compared with normative values. Finally, group differences in LV morphology were largely explained by differences in aerobic capacity. Taken together, these data suggest a prior burn injury itself does not result in pathological remodeling of the LV and support a role for aerobic exercise training to improve cardiac function.

Figure 1.

Differences in left ventricular (LV) morphology and function between nonburned controls (black bars), moderately burned (open bars), and severely burned individuals (gray bars). Despite a similar ejection fraction, moderately burned individuals had a lower end-diastolic volume (EDV), stroke volume, and cardiac output compared with the severely burned group. LV ejection fraction and concentricity were not different between the groups, suggesting no pathological remodeling in either patient groups. ^‡Significant difference compared with severe group P < .05 by one-way ANOVA. See Supplementary Material for cardiac responses indexed to body surface area.

Figure 2.

Relationship between absolute maximal whole-body oxygen consumption (VO_2max) and (A) left ventricular mass and (B) end-diastolic volume (EDV) in controls, moderately burned, and severely burned participants after controlling for sex differences between groups. Greater VO_2max was associated with a greater LV mass and EDV, evidence of physiological eccentric adaptation.

Figure 3.

Relationships between the extent of the burn injury (graded by body surface area; %BSA Burned) and (A) end-diastolic volume (EDV), (B) stroke volume, and (C) left ventricular mass in both moderate and severely burned individuals. Severity of burn injury was positively associated with increases in stroke volume. These relationships can be almost entirely explained by maximal aerobic capacity (VO_2max) as absolute VO_2max was also related to (D) EDV, (E) stroke volume, and (F) left ventricular mass in both moderate and severely burned individuals. Data shown are from correlation analysis adjusted for group differences in sex.