Lead screw driven sheath dilator

A sheath system comprising:

• a radially expandable sheath including:
• a continuous inner layer defining a central lumen extending therethrough, the inner layer having at least one folded portion;
• and
• a tubular strain relief layer provided along the inner layer positioned at a proximal end of the sheath and extending along at least a portion of a length of the sheath;
• and
• a dilator for expanding at least a portion of the sheath, the dilator including:
• a dilator shaft sized and configured to be received within the central lumen of the sheath;
• a knob coupled to a proximal end of the dilator shaft;
• a dilator hub rotatably coupled to the knob;
• and
• a pin coupling the dilator hub and the dilator shaft and preventing rotational movement therebetween,
• wherein rotational movement of the knob results in a corresponding axial movement of the dilator shaft in a direction along a longitudinal axis of the dilator to adjust a length of the dilator shaft received within the central lumen of the sheath,
• wherein at least a portion of the strain relief layer is configured to locally expand from an unexpanded configuration at a first diameter to an expanded configuration at a second, larger, diameter, and then locally contract at least partially back to the unexpanded configuration in response to an outwardly directed radial force exerted against the central lumen by the dilator shaft, and then locally contract at least partially back to the unexpanded configuration as the dilator shaft moves within the central lumen of the sheath.

A method of dilating a sheath comprising:

• providing a radially expandable sheath including:
• a continuous inner layer defining a central lumen therethrough, the inner layer having at least one folded portion;
• and
• tubular strain relief layer provided over the inner layer positioned at a proximal end of the sheath and extending along at least a portion of a length of the sheath, wherein at least a portion of the strain relief layer is configured to locally expand from an unexpanded configuration at a first diameter to an expanded configuration at a second, larger, diameter in response to an outwardly directed radial force exerted on the central lumen, and then locally contract at least partially back to the unexpanded configuration as the outwardly directed radial force is removed from the central lumen;
• providing a dilator for expanding at least a portion of the sheath, the dilator including:
• a dilator shaft sized and configured to be received within the central lumen of the expandable sheath;
• a knob coupled to a proximal end of the dilator shaft;
• a dilator hub rotatably coupled to the knob;
• a pin coupling the dilator hub and the dilator shaft and preventing rotational movement therebetween;
• coupling the dilator to the sheath;
• rotating the knob in a first direction causing the dilator shaft to engage the knob and resulting in a corresponding axial movement of the dilator shaft in a distal direction along a longitudinal axis of the dilator thereby increasing a length of the dilator shaft received within the central lumen of the sheath;
• advancing the dilator shaft through a portion of the central lumen of the sheath corresponding to the strain relief layer such that the dilator shaft exerts an outwardly directed radial force against the central lumen and causes the inner layer and the strain relief layer proximate the dilator shaft to locally expand from an unexpanded configuration to an expanded configuration;
• rotating the knob in a second direction opposite to the first direction, causing the dilator shaft to engage the knob and resulting in a corresponding axial movement of the dilator shaft in a proximal direction along the longitudinal axis of the dilator thereby reducing a length of the dilator shaft received within the central lumen of the sheath and removing the outwardly directed radial force exerted on the central lumen thereby causing the inner layer and the strain relief layer to locally contract at least partially back to the unexpanded configuration;
• uncoupling the dilator from the sheath;
• and
• removing the dilator from the sheath.