Controlled flow infusion microvascular dysfunction diagnostic and therapy
Methods and systems are provided for diagnosis and/or treatment of microvascular dysfunction, such as microvascular obstruction (MVO), in which the effects of collateral flow around a treatment site are addressed by injecting volumetric flows into a vessel using an infusion system to prevent or render negligible the collateral flow. Arterial pressures and fluidic flow rates sufficient to negate the collateral flow may be used to indicate the presence and/or severity of MVO for diagnostic and/or therapeutic purposes.
1 . A method of determining a vascular physiological parameter for a patient, the method comprising:
advancing a catheter having a lumen and a distal end and a first pressure sensor into an arterial vessel of the patient, the arterial vessel having blood flow;
delivering fluid at a plurality of flow rates over a time period through the lumen into the arterial vessel;
measuring a plurality of arterial pressures in the arterial vessel over the time period via the pressure sensor, the plurality of pressures corresponding to the plurality of flow rates;
determining a measure of aortic pressure of the patient, the measure of aortic pressure representative of an aortic pressure during the time period;
determining a resistance parameter using the measure of aortic pressure, a relationship between the plurality of flow rates over the time period and the plurality of arterial pressures over the time period, and a flow rate at which a corresponding pressure corresponds to the measure of aortic pressure; and
generating a representation of the resistance parameter.
2 . The method of claim 1 , wherein the step of generating the representation of the resistance parameter comprises displaying a visual indicator.
3 . The method of claim 1 , further comprising:
delivering a therapeutic agent at a plurality of therapeutic flow rates via the catheter into the arterial vessel.
4 . The method of claim 3 , wherein the step of generating the representation of the resistance parameter comprises generating an electronic output.
5 . The method of claim 4 , wherein the plurality of therapeutic flow rates are determined using the electronic output.
6 . The method of claim 5 , further comprising:
initiating a first occlusion of the blood flow prior to the step of delivering fluid at the plurality of flow rates.
7 . The method of claim 6 , further comprising:
discontinuing the first occlusion of the blood flow subsequent to the step of delivering fluid at the plurality of flow rates.
8 . The method of claim 7 , further comprising:
initiating a second occlusion of the blood flow, wherein the step of initiating the second occlusion of the blood flow occurs subsequent to the step of discontinuing the first occlusion of the blood flow and prior to the step of delivering the therapeutic agent.
9 . A system for diagnosing or treating a patient having an arterial vessel, the system comprising:
a catheter system having an occlusion device, a pressure sensor disposable distal to the occlusion device, and a lumen sized to deliver fluid therethrough to the arterial vessel distal of the occlusion device, the occlusion device being configured to occlude blood flow through the arterial vessel by initiating an occlusion of blood flow and subsequently discontinuing the occlusion; and
a computerized infusion system configured to be coupled to the catheter system and to:
cause the fluid to be infused at a plurality of flow rates via the lumen and subsequent to the occlusion device initiating the occlusion and prior to the occlusion device discontinuing the occlusion;
communicate with the first pressure sensor to receive a plurality of pressure measurements over a time period, the plurality of pressure measurements corresponding to the plurality of flow rates over the time period;
calculate a resistance parameter using an aortic pressure measurement representative of an aortic pressure during the time period, the plurality of pressure measurements over the time period, and the plurality of flow rates over the time period, and a flow rate at which a corresponding pressure corresponds to the aortic pressure measurement;
and
generate a representation of the resistance parameter.
10 . The system of claim 9 , wherein the computerized infusion system is further configured to cause a therapeutic agent to be infused at a plurality of therapeutic infusion rates.
11 . The system of claim 10 , wherein the representation of the resistance parameter comprises an electronic output.
12 . The system of claim 11 , wherein the plurality of therapeutic infusion rates are determined based on the electronic output.
13 . The system of claim 9 , wherein the occlusion device may be activated to occlude the arterial vessel, and
wherein the computerized infusion system is further configured to selectively activate the occlusion device.
14 . The system of claim 10 , wherein the representation of the resistance parameter comprises a visual image.
15 . The system of claim 14 , wherein the computerized infusion system is coupled to a display device, the display device configured to display the visual image.
16 . A system for diagnosing or treating a patient having an arterial vessel, the system comprising:
a catheter system having a catheter body carrying an occluder, a first pressure sensor located distal to the occluder,
a second pressure sensor (1) located proximal to the occluder and remote from (a) the first pressure sensor and (b) the catheter body, and (2) configured to obtain aortic pressure measurements, and a lumen sized to deliver fluid to the arterial vessel distal of the occluder; and
a computerized infusion system configured to be coupled to the catheter system and to:
cause the fluid to be infused at a plurality of flow rates;
communicate with the first pressure sensor to receive a plurality of downstream pressure measurements over a time period, the plurality of downstream pressure measurements corresponding to the plurality of flow rates over the time period;
communicate with the second pressure sensor to receive aortic pressure measurements, the aortic pressure measurements representative of an aortic pressure during the time period; and
calculate a resistance parameter based on an aortic pressure measurement measured by the second sensor, the plurality of downstream pressure measurements over the time period, and the plurality of flow rates over the time period.
17 . The system of claim 16 , wherein the computerized infusion system is further configured to infuse a therapeutic agent at a first infusion rate determined by the resistance parameter.
18 . The system of claim 17 , wherein the computerized infusion system is further configured to cause the fluid to be infused for a predetermined diagnostic interval, to infuse the therapeutic agent at the first infusion rate for a first predetermined treatment interval, and to infuse the therapeutic agent at a second infusion rate for a second predetermined treatment interval, the second infusion rate being based on the resistance parameter.
19 . The system of claim 16 , wherein the computerized infusion system is further configured to operate the occluder.
20 . The system of claim 16 , wherein the computerized infusion system is coupled to a display device, the display device configured to display an indication of the resistance parameter.
21 . The method of claim 1 , further comprising:
initiating a first occlusion of the blood flow prior to the step of delivering fluid at the plurality of flow rates,
the step of determining the measure of aortic pressure includes determining the measure of aortic pressure prior to initiating the first occlusion.
22 . The method of claim 21 , wherein the step of determining the measure of aortic pressure includes determining the measure of aortic pressure using the pressure sensor.
23 . The method of claim 22 , wherein the pressure sensor is a pressure sensing guidewire, a distal end of the pressure sensing guidewire being disposed distal to the catheter during the step of determining the measure of aortic pressure.
24 . The method of claim 21 , wherein the pressure sensor is a first pressure sensor,
the step of determining the measure of aortic pressure includes determining the measure of aortic pressure of the patient via a second pressure sensor remote from the first pressure sensor and separate from the catheter.
25 . The method of claim 24 , wherein the step of determining the measure of aortic pressure via the second pressure sensor occurs during the time period.
26 . The method of claim 1 , further comprising:
performing regression analysis using the plurality of flow rates and the plurality of pressures corresponding to the plurality of flow rates to determine the flow rate at which the corresponding pressure corresponds to the measure of aortic pressure.
27 . The method of claim 1 , wherein the resistance parameter is representative of microvascular dysfunction.
28 . The method of claim 1 , wherein delivering fluid at the flow rate at which the corresponding pressure corresponds to the measure of aortic pressure renders negligible any collateral flow associated with the arterial vessel.
29 . The method of claim 1 , wherein the flow rate at which the corresponding pressure corresponds to the measure of aortic pressure is calculated based on the relationship between the plurality of flow rates over the time period and the plurality of arterial pressures over the time period.
30 . The method of claim 1 , wherein the plurality of flow rates over the time period does not include the flow rate at which the corresponding pressure corresponds to the measure of aortic pressure.
31 . The system of claim 9 , wherein the computerized infusion system is configured to cause the fluid to be infused at the plurality of flow rates subsequent to the occlusion device initiating the occlusion and prior to the occlusion device discontinuing the occlusion.
32 . The system of claim 9 , wherein the pressure sensor is a first pressure sensor, the catheter system further including a second pressure sensor located proximal to the occlusion device and configured to obtain the aortic pressure measurement representative of the aortic pressure during the time period.
33 . The system of claim 31 , wherein the computerized infusion system is configured to: (1) obtain the aortic pressure measurement prior to the occlusion device initiating the occlusion, and (2) receive the plurality of pressure measurements subsequent to the occlusion device initiating the occlusion and prior to the occlusion device discontinuing the occlusion.
34 . The system of claim 9 , wherein the pressure sensor is disposable distal to the lumen.
35 . The system of claim 9 , wherein the pressure sensor is a pressure sensing guidewire.
36 . The system of claim 16 , wherein the computerized infusion system is configured to calculate the resistance parameter based on a flow rate at which a corresponding pressure corresponds to the aortic pressure measurement.
37 . The system of claim 36 , wherein the flow rate is greater than all of the plurality of flow rates, the computerized infusion system configured to calculate the flow rate using regression analysis.