Hemodynamic Changes Induced by Recreational Scuba Diving: Baseline Echocardiographic Variables

Baseline echocardiographic examinations were normal in all volunteers. Mean indexed LVM was 101 ± 21 g/m2. Mean aortic cross-section surface was 4.2 ± 0.54 cm2. A tricuspid regurgitant flow was identified in 7 of 10 divers, and instantaneous systolic pressure gradient from the RV to RA could be assessed in these subjects.
None of the divers presented any disorders suggesting a diving accident.
Circulating Bubbles Detection: Circulating bubbles were detected in all divers. Bubbles were observed in right cavities of the heart using 2D echocardiography in seven divers. Pulsed Doppler confirmed the existence of venous gas emboli in these cases and detected circulating bubbles that were not seen in 2D echography in three other divers. Discrepancies were observed in subjects with poor image quality. Circulating bubbles were graded according to the 2D echocardiographic and pulsed Doppler grade. A grade 3 was observed in seven divers, grade 2 in one diver, and grade 1 in two divers. No circulating bubbles were detected in left heart cavities.

Cardiac Function Assessment After Diving: Hemodynamic variables after diving in comparison to baseline mean values are shown in Table 2. Systolic and diastolic arterial pressures did not vary significantly after diving. HR significantly increased, whereas a significant decrease of the SV was observed after diving. CO, assessed by aortic blood flow, remained unchanged.
LA and LV Diameters: LV and LA diameters significantly decreased after diving (Table 3). %FS remained unchanged after diving. LV Filling: Study of the LV filling profile (Table 4) showed a significant decrease after diving in the ratio between the peak velocity and VTI of the initial flow (E wave), and peak velocity and VTI of the late flow A wave. This profile suggests an increase in the relative contribution of atrial contraction to the total LV filling. Furthermore, IVRT increased while pressure half-time remained unchanged after diving.
Right Cavities: RV diameters remained unchanged after diving (Table 5). Peak velocity of the tricuspid regurgitant flow increased after diving, suggesting an increase in systolic RV/Rag (p < 0.05).

Table 2—Hemodynamic Variables

Variables BasalConditions AfterDiving p Value
Systolic arterial pressure, mm Hg 119.3 ± 9.8 118.6 ± 10 0.7
Diastolic arterial pressure, mm Hg 75 ± 4 74.6 ± 3.8 0.6
HR, beats/min 64 ± 9 7±7 < 0.001t
SV, mL 85 ± 16 79 ± 17 0.02т
CO, L/min 5.35 ± 0.71 5.7 ± 0.93 0.1

Table 3—LA and LV Diameters

Variables Basal Conditions After Diving p Value
LA, mm 34 ± 5 31 ± 5 < 0.05 т
LVEDD, mm 51 ± 3 49 ± 4 < 0.05 т
LVESD, mm 35 ± 4 32 ± 4 < 0.05 т
%FS 32 ± 6 33 ± 7 0.5

Table 4—LV Filling

Variables BasalConditions AfterDiving p Value
Peak E velocity, cm/s 67 ± 14 60 ± 14 < 0.05
Peak A velocity, cm/s 52 ± 13 61 ± 11 0.1
E/A ratio 1.4 ± 0.5 1 ± 0.4 < 0.005 т
Pressure half-time, ms 66 ± 16 68 ± 14 0.7
IVRT, ms 86 ± 10 99 ± 12 0.005t
E-wave VTI, cm 11.7 ± 3.8 9.4 ± 2.1 < 0.01т
A-wave VTI, cm 4.9 ± 1.3 5.1 ± 0.9 0.1
A-wave VTI/(E-wave 30 ± 9 36 ± 6 < 0.02т
VTI + A-wave VTI), %

Table 5—Right Cavities

Variables BasalConditions AfterDiving p Value
RVEDD, mm 23 ± 5.3 22.8 ± 4.2 0.5
RVESD, mm 18.6 ± 5.3 17.5 ± 2.7 0.3
RV/Rag (seven divers) 18.9 ± 6.9 26.9 ± 7.2 0.01т
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