[Changes in cardiac function during recreational diving].

Underwater diving is a widely practised leisure activity. As cardiac patients may wish to participate, cardiologists should be aware of potential changes of cardiac function during diving. Multiple factors may affect haemodynamics. Firstly, changes in pressure, secondary to ventilation of a high density gas mixture which increases afterload. Hyperoxia is the principal factor which slows the heart rate, a commonly observed phenomenon. Excitability and conduction speed may be modified by the increase in hydrostatic pressure. During decompression, gaseous pulmonary embolism may increase right heart pressures and cause a paradoxical embolism may increase right heart pressures and cause a paradoxical embolism in patients with a right-to-left shunt. Immersion increases the preload. Exposure to cold also plays a role increasing afterload and slowing the heart rate. These factors may disturb cardiac function and expose cardiac patients to accidents during underwater diving.