1. Endovascular Selective Cerebral Hypothermia for Neuroprotection
Ronald J. Solar, Ph.D.
ThermopeutiX, Inc.
San Diego, CA

2. Ronald Solar, Ph.D.
I have the following relevant financial relationships:
Consultant
ThermopeutiX, Inc.
Stockholder

3. Introduction Failures due to cooling techniques employed
Major limitations in acute ischemic stroke (AIS) therapies
Time limitation for lytics excludes most patients
Mech revascularization limited by small number of trained physicians
Recanalization limited by reperfusion injury* —
need neuroprotection
Therapeutic hypothermia (TH) — the most potent neuroprotectant in the laboratory
Influences a variety of cell death mechanisms — “combinational protective strategy”
Of the many challenges in treating AIS, protecting the brain from the onslaught of ischemia and reperfusion injury is perhaps most important In the laboratory, hypothermia has been shown to be one of the most robust neuroprotectants identified to date, since it acts on virtually all of the pathways that lead to cell death, and its role in mitigating reperfusion injury is of particular importance.
However, in the clinical setting the techniques used have simply not worked
Failures due to cooling techniques employed
BUT, a failed therapy in AIS
*K Fargen et al. J Neurointerv Surg 2013; 5:506-11
J Bai and P Lyden. Int J Stroke 2015; 10:143–152

4. TwinFlo™ Catheter — Novel endovascular selective cerebral hypothermia device and technique
Stroke literature shows efficacy of TH is critically dependent on the duration and depth of hypothermia, and that there may be an efficacy threshold of ≤31 ºC*
Current TH devices and techniques provide systemic cooling, which is slow, limited to ≥32°C, and unpredictable in cooling the brain
TF provides very rapid, deep and selective brain cooling with faster cooling rates, and temperatures much lower than what can be achieved by any other hypothermia device and technique
Stroke literature literature shows that time and temperature are the most important parametrs of hypothermia, and that there may be an efficacy threshold around 30 ºC.
Current TH devices and techniques provide systemic cooling, which is slow and unpredictable in cooling the brain. And detrimental systemic effects, in particular, cardiac dysfunction, limit systemic hypothermia to temperatures above which may be efficacious.
To address these limitations, we designed a novel endovascular selective cerebral hypothermia device and technique that we call TwinFlo that provides…
*D Krieger and M Yenari. Stroke 2004; 35:
H Van der Worp, et al. Brain 2007; 130:

5. Percutaneous selective cerebral hypothermia 2. Warm blood removed,
cooled blood returned.
3. Carotid
artery perfusion.
TwinFlo is a proprietary perfusion catheter that isolates and selectively perfuses the CA with cold blood. It can be used with any existing extracorporeal blood circuit, and the set up is simplified since no membrane oxygenation is required.
TwinFlo is introduced by standard femoral technique, and advanced to the common or internal carotid artery. As illustrated here, blood is withdrawn from a port in the catheter located in the aortic arch, cooled extracorporeally, and them pumped directly to the brain beyond a very atraumatic occlusion balloon, so that the brain only receives cold blood.
1. Central aorta.

6. Counter-current flow provides insulation
The patented counter-current blood flow design provides effective insulation

7. TwinFlo™ Catheter — Novel endovascular selective cerebral hypothermia device and technique
In addition to providing hypothermia, the design allows selective delivery of drugs (e.g., lytics, Mg) and other devices (e.g., stentreivers and microcatheters), as well as control of perfusion pressure; recanalization be done in a cooled, protected brain to avoid reperfusion injury.

8. In Vivo Pig Studies Demonstrated cerebral cooling rates up to 2°C/min
Brain temperatures as low 15°C
Minimal systemic cooling
No adverse events
Normal heart rhythm, systemic arterial blood pressure, arterial blood values
No rebound hyperthermia with passive rewarming
Our preclinical work was done in large pigs where we demonstrated…

9. Porcine stroke model*
3 hours of ischemia followed by 3 hours of reperfusion
Pigs randomized to selective cooling or normothermia during reperfusion period. Analysis blinded.
Blood pressure, heart rate, hemoglobin, glucose, and oxygenation levels did not differ between normothermic and hypothermic cohorts
Statistically significant reduction in stroke volume by selective cooling with TwinFlo™ to mean 28°C for 1-3 hrs
In a randomized porcine stroke study, with blinded analysis, selectively cooling the brain with TwinFlo to 28°C for 1-3 hrs resulted in a statistically significant reduction in stroke volume.
*Mattingly TK, et al. J NeuroIntervent Surg 2016;8:

10. Initial Human Experience
Neurosurgical repair of giant aneurysm of MCA in a 59 yom; 2 hr occlusion time
TwinFlo™ selectively cooled brain at 26°C with systemic normothermia. Full, rapid recovery with no neurological deficit
Cardiac arrest, non-shockable PVT in a 38 yom; no flow >8 min; no response after 44 min CPR and 10 hours of 33°C ECMO*
TwinFlo™ selectively cooled brain at ~22°C (27°C nasal temp.) for 12 hours. Full, rapid recovery with no neurological deficit
Initial human experience with TwinFlo to date has been in the setting of neurosurgery and cardiac arrest. During the extensive occlusion time required to surgically repair a giant aneurysm, TwinFlo selectively cooled the brain to 26°C providing neuroprotection, while maintaining systemic normothermia. The neurosurgeon noted that patient recovery, with no neurological deficit appeared to be much quicker than typically seen in this setting.
In a 38 YOM presenting with non-shockable pulseless ventricular tachycardia and no flow >8 min., TwinFlo was used as a last resort after no response to 44min of CPR and 10 hours of ECMO.
TwinFlo selectively cooled the brain to ~22°C for 12 hr. The patient made a full recovery with no neurological deficit.
*Wang C-H, et al. BMJ Case Rep doi: /bcr

11. Conclusion
This new endovascular system and technique may offer an improved method for neuroprotection in cardiac arrest, acute stroke and other conditions producing cerebral ischemia