962 Echocardiographic assessment of left ventricular morphology and function in breath-hold sea divers

Introduction: There are no many studies into human effects of breath- hold submersion of the whole body on heart volume and function. Apart from the reduction in heart rate that was reported in many subjects, left ventricular dysfunction was hypothesized in intense apnoeic exercise in deep water. In this study we sought to evaluate left ventricular (LV) dimen- sions and function in professional sea divers, by using conventional echocardiography. Methods: Fifteen healthy male subjects, mean aged 28+3, were studied on board of the support ship. Doppler echocardiography was performed be- fore and soon after an usual session of breath-hold sea diving. All athletes performed a series of apnoeic exercises as follows: single submersion from 50 to 180 s, up to 40 meters maximum dept, overall session length of 30 minutes. Heart rate (HR) and blood pressure (BP) were also measured be- fore and after exercise. Results: Heart rate was 71±7 bpm before and 72±8 bpm after apnoea (change: +3±13%, p=NS). Systolic and diastolic BP were 123±12 mm Hg and 78±7 mm Hg before, and 118±15 mm Hg (-4±9%, p=NS) and 78±10 mm Hg (+1±14%, p=NS) after apnoea. Main echocardiographic findings are reported in table underneath. Conclusions: Findings from the present study suggest that breath-hold sub- mersion in professional sea-divers induces mild but statistically significant dias- tolic dilatation of the left ventricle with weak reduction of systolic diameter, likely due to increased systolic function. In fact, septal and infero/lateral wall motion improve, as well as circumferential fractional shortening, irrespective of signifi- cant changes in BP. The most likely explanation is a transient blood shift phe- nomenon, as already demonstrated in deepest submersion activities.