Method and system for patient-specific modeling of blood flow

• US 8,812,245 B2
• Filed: 12/12/2013
• Issued: 08/19/2014
• Est. Priority Date: 08/12/2010
• Status: Active Grant

• Current Assignee: Heartflow Inc.
• Original Assignee: Heartflow Inc.
• Inventors: Taylor, Charles A.
• Primary Examiner(s): Clow, Lori A
• Application Number:
  US14/104,766
• Publication Number:
  US 20140107935A1
• Time in Patent Office: 250 Days
• Field of Search: None
• US Class Current: 702/19
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Abstract

Embodiments include a system for determining cardiovascular information for a patient. The system may include at least one computer system configured to receive patient-specific data regarding a geometry of the patient'"'"'s heart, and create a three-dimensional model representing at least a portion of the patient'"'"'s heart based on the patient-specific data. The at least one computer system may be further configured to create a physics-based model relating to a blood flow characteristic of the patient'"'"'s heart and determine a fractional flow reserve within the patient'"'"'s heart based on the three-dimensional model and the physics-based model.

Claims

1. A method for non-invasive assessment of coronary artery stenosis, comprising:

extracting, using at least one processor, patient-specific anatomical measurements of the coronary arteries from medical image data of a patient acquired during a rest state;

calculating, using the at least one processor, patient-specific rest state boundary conditions of a model of coronary circulation representing the coronary arteries based on the patient-specific anatomical measurements and non-invasive clinical measurements of the patient at rest;

calculating, using the at least one processor, patient-specific hyperemic boundary conditions of the model of coronary circulation using the rest boundary conditions and using a model for simulated hyperemia;

simulating, using the at least one processor, hyperemic blood flow and pressure across at least one stenosis region of at least one coronary artery using the model of coronary circulation and the patient-specific hyperemic boundary conditions; and

calculating, using the at least one processor, fractional flow reserve (FFR) of the at least one stenosis region based on the simulated hyperemic blood flow and pressure.

2. The method of claim 1, wherein the coronary circulation model comprises one-dimensional computational models representing the coronary arteries and aorta of the patient.

3. The method of claim 2, wherein the coronary circulation model further comprises a reduced order semi-empirical stenosis model representing the at least one stenosis region, coupled to the one-dimensional computational model representing the at least one coronary artery.

4. The method of claim 2, wherein the coronary circulation model further comprises a full-order three-dimensional computational model of the at least one stenosis region, coupled to the one-dimensional computational model representing the at least one coronary artery.

5. The method of claim 2, wherein the coronary circulation model further comprises lumped models representing coronary microvascular beds, each coupled to a termination of a one-dimensional computational model representing a coronary artery branch.

6. The method of claim 1, wherein calculating patient-specific rest state boundary conditions of a model of coronary circulation representing the coronary arteries based on the patient-specific anatomical measurements and non-invasive clinical measurements of the patient at rest comprises:

calculating a resting microvascular resistance at the termination of each of a plurality of branches based on the patient-specific anatomical measurements and the non-invasive clinical measurements of the patient at rest.

7. The method of claim 6, wherein calculating patient-specific hyperemic boundary conditions of the model of coronary circulation based on the rest boundary conditions and a model for simulated hyperemia comprises:

calculating the hyperemic microvascular resistance at the termination of each of the plurality of branches based on the calculated resting microvascular resistance.

8. The method of claim 7, wherein calculating a resting microvascular resistance at the termination of each of the plurality of branches based on the patient-specific anatomical measurements and the non-invasive clinical measurements of the patient at rest comprises:

calculating a mean arterial pressure (MAP) based on a heart rate, a systolic blood pressure, and a diastolic blood pressure of the patient;

calculating a resting myocardial perfusion based on the heart rate and the systolic blood pressure of the patient;

calculating a total resting coronary flow based on the resting myocardial perfusion and a mass of the left ventricle of the patient; and

calculating the resting microvascular resistance at the termination of each of the plurality of branches based on the MAP and the total resting coronary flow.

9. The method of claim 8, wherein the mass of the left ventricle is estimated from the medical image data of the patient.

10. The method of claim 7, wherein calculating the hyperemic microvascular resistance at the termination of each of the plurality of branches based on the calculated resting microvascular resistance comprises:

determining a patient-specific total coronary resistance index (TCRI) based on the non-invasive clinical measurements of the patient; and

calculating the hyperemic microvascular resistance at the termination of each of the plurality of branches based on the calculated hyperemic microvascular resistance and the patient-specific TCRI.

11. The method of claim 10, wherein determining a patient-specific total coronary resistance index (TCRI) based on the non-invasive clinical measurements of the patient comprises:

calculating a resting average peak velocity based on a heart rate and a systolic blood pressure of the patient;

calculating a coronary flow velocity reserve (CFVR) CFVR value for each branch of the coronary arteries based on an age of the patient; and

calculating the TCRI for each branch based on the CFVR value and an estimated resting mean arterial pressure (MAP).

12. The method of claim 10, wherein determining a patient-specific total coronary resistance index (TCRI) based on the non-invasive clinical measurements of the patient comprises:

calculating the TCRI based on a heart rate of the patient.

13. The method of claim 1, wherein calculating fractional flow reserve (FFR) of the at least one stenosis region based on the simulated hyperemic blood flow and pressure comprises:

calculating the FFR of the at least one stenosis region as a ratio of a mean simulated hyperemic pressure distal to the at least one stenosis and a mean simulated hyperemic aortic pressure over a cardiac cycle.

14. A non-transitory computer readable medium storing computer program instructions for non-invasive assessment of coronary artery stenosis, the computer program instructions when executed by a processor cause the processor to perform operations comprising:

extracting patient-specific anatomical measurements of the coronary arteries from medical image data of a patient acquired during a rest state;

calculating patient-specific rest state boundary conditions of a model of coronary circulation representing the coronary arteries based on the patient-specific anatomical measurements and non-invasive clinical measurements of the patient at rest;

calculating patient-specific hyperemic boundary conditions of the model of coronary circulation using the rest boundary conditions and using a model for simulated hyperemia;

simulating hyperemic blood flow and pressure across at least one stenosis region of at least one coronary artery using the model of coronary circulation and the patient-specific hyperemic boundary conditions; and

calculating fractional flow reserve (FFR) of the at least one stenosis region based on the simulated hyperemic blood flow and pressure.

15. The non-transitory computer readable medium of claim 14, wherein the coronary circulation model comprises one-dimensional computational models representing the coronary arteries and aorta of the patient.

16. The non-transitory computer readable medium of claim 14, wherein calculating patient-specific rest state boundary conditions of a model of coronary circulation representing the coronary arteries based on the patient-specific anatomical measurements and non-invasive clinical measurements of the patient at rest comprises:

calculating a resting microvascular resistance at the termination of each of the plurality of branches based on the patient-specific anatomical measurements and the non-invasive clinical measurements of the patient at rest.

17. The non-transitory computer readable medium of claim 16, wherein calculating patient-specific hyperemic boundary conditions of the model of coronary circulation based on the rest boundary conditions and a model for simulated hyperemia comprises:

calculating the hyperemic microvascular resistance at the termination of each of the plurality of branches based on the calculated resting microvascular resistance.

18. The non-transitory computer readable medium of claim 17, wherein calculating a resting microvascular resistance at the termination of each of the plurality of branches based on the patient-specific anatomical measurements and the non-invasive clinical measurements of the patient at rest comprises:

calculating a mean arterial pressure (MAP) based on a heart rate, a systolic blood pressure, and a diastolic blood pressure of the patient;

calculating a resting myocardial perfusion based on the heart rate and the systolic blood pressure of the patient;

calculating a total resting coronary flow based on the resting myocardial perfusion and a mass of the left ventricle of the patient; and

calculating the resting microvascular resistance at the termination of each of the plurality of branches based on the MAP and the total resting coronary flow.

19. The non-transitory computer readable medium of claim 17, wherein calculating the hyperemic microvascular resistance at the termination of each of the plurality of branches based on the calculated resting microvascular resistance comprises:

determining a patient-specific total coronary resistance index (TCRI) based on the non-invasive clinical measurements of the patient; and

calculating the hyperemic microvascular resistance at the termination of each of the plurality of branches based on the calculated hyperemic microvascular resistance and the patient-specific TCRI.

20. The non-transitory computer readable medium of claim 19, wherein determining a patient-specific total coronary resistance index (TCRI) based on the non-invasive clinical measurements of the patient comprises:

calculating a resting average peak velocity based on a heart rate and a systolic blood pressure of the patient;

calculating a coronary flow velocity reserve (CFVR) value for each branch of the coronary arteries based on an age of the patient; and

calculating the TCRI for each branch based on the CFVR value and an estimated resting mean arterial pressure (MAP).

21. The non-transitory computer readable medium of claim 19, wherein determining a patient-specific total coronary resistance index (TCRI) based on the non-invasive clinical measurements of the patient comprises:

calculating the TCRI based on a heart rate of the patient.

22. The non-transitory computer readable medium of claim 14, wherein calculating fractional flow reserve (FFR) of the at least one stenosis region based on the simulated hyperemic blood flow and pressure comprises:

calculating the FFR of the at least one stenosis region as a ratio of a mean simulated hyperemic pressure distal to the at least one stenosis and a mean simulated hyperemic aortic pressure over a cardiac cycle.

23. A method for non-invasive assessment of coronary artery stenosis, comprising:

extracting, using at least one processor, patient-specific anatomical measurements of the coronary arteries from medical image data of a patient acquired during a hyperemia state;

calculating, using at least one processor, patient-specific hyperemic boundary conditions of a model of coronary circulation representing the coronary arteries using the patient-specific anatomical measurements and using non-invasive clinical measurements of the patient at hyperemia;

simulating, using at least one processor, hyperemic blood flow and pressure across at least one stenosis region of at least one coronary artery using the model of coronary circulation and the patient-specific hyperemic boundary conditions; and

calculating, using at least one processor, fractional flow reserve (FFR) of the at least one stenosis region based on the simulated hyperemic blood flow and pressure.