CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Australian provisional application no. 2017900356, filed on 6 Feb. 2017, the entire content of which is herein incorporated by reference.

TECHNICAL FIELD

The present invention relates to methods and apparatuses for monitoring cardiac dysfunction such as irregularities in cardiac wall motion.

BACKGROUND

Monitoring of cardiac wall motion is important in many clinical cardiac procedures. As the number and complexity of percutaneous intracardiac procedures continues to increase and a variety of new technologies for structural heart disease and electrophysiology interventions are introduced, the risk of periprocedural injury to the heart also increases. Many of these procedures have in common the need for intraprocedural anticoagulation and a number require transseptal puncture to access the heart.

Percutaneous based catheterisation is the most rapidly growing technique in the field of interventional cardiology for diagnosing and treating diseases in the heart. Perforation or full-thickness injury of the heart wall during catheterisation procedures occurs at a rate of approximately 1 to 6% clinically depending on the aetiology and complexity of the procedure. This often leads to pericardial effusion, which involves the ejection of blood or fluid from within the perforated (or injured) cardiac chamber into the pericardial space, and more seriously cardiac tamponade, which is the crushing of the heart due to an accumulation of blood or fluid in the pericardial space, thus preventing the heart from beating. Both conditions lead to a loss of contractile function of the heart wall.

Monitoring cardiac function is also desirable for coronary intervention procedures. Coronary intervention is a procedure which aims to restore blood flow to an occluded artery of the heart via intravascular deployment of a balloon designed to distend the artery or deploy a stent. The act of ballooning in coronary interventions temporarily causes cardiac ischemia (lack of oxygen due to interrupted coronary blood flow). This may lead to impaired cardiac function, such as loss of contractility of the heart wall, and could contribute to sudden cardiac death.

Monitoring cardiac function may also be desirable for cardiac ablation procedures. It is well recognised that blood volume pressure of the heart may increase due to the overload of physiological normal saline (irrigation) during cardiac ablation procedures. The increased blood volume pressure can have adverse effects on cardiac wall motion, leading to complications during the procedure.

In the electrophysiology setting, an increased risk of pericardial effusion may be associated with intracardiac or epicardial arrhythmia ablations of any chamber of the heart, placement of biventricular pacemakers, and implantable cardioverter-defibrillators.

Implantable cardioverter-defibrillators (ICDs) or pacemakers are often implanted in patients at risk of cardiac arrhythmias or to enable cardiac rate control (pacing) in patients with cardiac dysfunction. The modality of treatment by such devices is achieved by electrical stimulation of the heart muscle via an electrode imbedded within the heart wall. Under certain situations, cardiac electrical stimulation by such devices may be ineffective when physiological changes to the heart occur, such as ischemia or heart failure, which may result in loss of contractile function of the heart wall and may lead to potentially life threatening circumstances. As such, effective delivery of therapy from ICDs or pacemakers depends upon accurate measurement of intrinsic cardiac activity.

Current methods used to monitor cardiac activity, particularly pericardial effusion and cardiac tamponade, involve hemodynamic monitoring (blood pressure measurement), echocardiographic assessment, and fluoroscopic assessment. Hemodynamic assessment, which is often performed continuously in cardiac procedures, has low sensitivity to early changes in cardiac contractility. Current imaging modalities involving x-ray and ultrasound are also limited as they are often utilised reactively to hemodynamic compromise and not proactively.

Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each claim of this application.

SUMMARY

An aspect of the present disclosure provides a method of monitoring cardiac dysfunction using an indwelling probe inserted within the coronary sinus of a patient, the probe having motion sensing means configured to sense motion of the probe based on movement of the wall of the coronary sinus, the method comprising:

obtaining data from the motion sensing means and processing said data to monitor for cardiac dysfunction.

Another aspect of the present disclosure provides an apparatus comprising:

an indwelling probe comprising:an elongate body adapted for insertion within a coronary sinus of a patient; andmotion sensing means coupled to the elongate body and configured to sense motion of the probe based on movement of the wall of the coronary sinus; and

a processor coupled to the probe for receiving data obtained from the motion sensing means and processing said data to monitor for cardiac dysfunction.

The indwelling probe may have a diameter ranging from 5 to 8 Fr (1.7 to 2.7 mm) or otherwise. The indwelling probe may have a length ranging from 65 cm to 115 cm or otherwise.

The data from the motion sensing means may comprise acceleration data, indicative of acceleration and/or deceleration of the wall.

The method and apparatus may comprise:

recording acceleration data from the motion sensing means;

deriving displacement data from the acceleration data; and

comparing the displacement data with baseline data.

In yet a further aspect of the present disclosure, there is provided a method of monitoring cardiac dysfunction using an indwelling probe inserted within a heart vessel, the probe having motion sensing means configured to sense motion of the probe, the method comprising:

recording acceleration data from the motion sensing means based on movement of the wall of the heart vessel;

deriving displacement data from the acceleration data; and

comparing the displacement data with baseline data to monitor for cardiac dysfunction.

Another aspect of the present invention provides an apparatus comprising:

an indwelling probe comprising:an elongate body adapted for insertion within a heart vessel; andmotion sensing means coupled to the elongate body and configured to sense motion of the probe based on movement of the wall of the heart vessel; and

a processor coupled to the probe for receiving data obtained from the motion sensing means and processing said data to monitor for cardiac dysfunction.

A further aspect of the present invention provides an apparatus comprising:

an indwelling probe comprising:an elongate body adapted for insertion within a chamber of the heart; andmotion sensing means coupled to the elongate body and configured to sense motion of the probe based on movement of the wall of the chamber of the heart; and

a processor coupled to the probe for receiving data obtained from the motion sensing means and processing said data to monitor for cardiac dysfunction.

In any of the above methods, the processor may form part of a computer system and/or the processing steps may be conducted at least partially using a computer system. The computer system may comprise a computer device with a processor and memory.

The motion sensing means may comprise a three-axis accelerometer located at or adjacent a distal end of the elongate body. Acceleration data recorded from the three-axis accelerometer may be filtered to remove signal artefact arising from, for example, respiration movement, cardiac ectopy or patient movement. The probe may be provided at least in part by a catheter that includes the elongate body.

Deriving displacement data may comprise performing a first calculation to determine first displacement data from the acceleration data and performing a second calculation to determine volumetric displacement data of the probe from the first displacement data. Comparing the displacement data with baseline data may comprise comparing volumetric displacement data determined from the second calculation with baseline data.

At least one electrode may be disposed on the external surface of the elongate body. In some embodiments, two or more electrodes may be spaced longitudinally along the elongate body. The electrode(s) may be configured to detect electrograms from cardiac activity. In some embodiments, the same or additional electrodes may be configured to deliver electrical current for stimulation of the heart. Electrograms detected from the electrode(s) may be recorded and may, in addition, be used to calculate beat-to-beat cardiac cycle timing data. The beat-to-beat cardiac cycle timing data may then be used to correct the first displacement data to account for displacement drift of the probe. The second calculation to determine volumetric displacement data of the probe may be based on the corrected first displacement data, for example.

One or more sensors may be coupled to the processor. The sensor(s) may be configured to provide additional reference data, such as external reference data. The sensor(s) may comprise skin surface electrode(s), temperature sensor(s) (e.g., thermocouples or thermistors), ultrasound probe, radiofrequency patch, magnetometer or induction coil, x-ray fluoroscopy apparatus, and/or three-dimensional electroanatomical mapping system. The additional reference data may comprise electrocardiograms, echocardiograms, bio-impedance data, magnetic field information or induction coil data, x-ray fluoroscopy data, catheter positioning information, temperature information and/or anatomical structure depending on the sensor(s) used.

In some embodiments, electrocardiograms from the skin surface electrode(s) may be recorded and may, in addition, be used to calculate beat-to-beat cardiac cycle timing data. Again, the beat-to-beat cardiac cycle timing data may then be used to correct the first displacement data to account for displacement drift of the probe. The second calculation to determine volumetric displacement data of the probe may be based on the corrected first displacement data, for example. Alternatively, or additionally, the additional reference data may be used to correct the acceleration data to account for positional mis-orientation of the probe, filter the acceleration data to remove signal artefact, and/or provide additional diagnostic information regarding cardiac function. Once again, the second calculation to determine volumetric displacement data of the probe may be based on the corrected first displacement data.

In some embodiments, a single three-axis accelerometer may be provided. Alternatively, two or more three-axis accelerometers may be provided that may be spaced longitudinally along the elongate body. Deriving volumetric displacement data may comprise performing a first calculation to determine first displacement data from the acceleration data, cross-validating the first displacement data to differentiate artefact motion data from validated displacement data, and performing a second calculation to determine volumetric displacement data of the probe from the validated displacement data. Additionally, or alternatively, cardiac wall deformation data, assessed as the displacement deviations that may arise between accelerometer pairs, may be calculated based on the validated displacement data.

In any of the above aspects and embodiments, one or more alerts may be generated when the volumetric displacement data and/or the cardiac wall deformation data changes significantly from baseline data.

A further aspect of the present invention provides a method comprising:

inserting an indwelling probe within a coronary sinus of a patient, the probe having motion sensing means configured to sense motion of the probe based on movement of the wall of the coronary sinus; and

coupling the probe to a processor, the processor being configured to receive and process acceleration data obtained from the motion sensing means to monitor for cardiac dysfunction.

In one embodiment, a distal end of the probe may be located adjacent to the valve of Vieussens of the coronary sinus, for example.

The motion sensing means may comprise a three-axis accelerometer located adjacent the distal end of the probe such that, when the indwelling probe is positioned for use, the accelerometer is positioned within the distal aspect of the coronary sinus in approximation to the postero-lateral to lateral aspect of the atrioventricular groove of the heart.

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

