The Science
Grounded in three decades of thermal-modulation evidence
Every documented benefit of vascular heating, and every documented harm, scales with dose. A controlled, moderate thermal dose is anti-proliferative and improves acute lumen gain without the thrombosis penalty seen at high temperatures. That window is what EVA™ is built around.
Central thesis
TBA's safety and effectiveness are dose-dependent. A controlled, moderate thermal dose is consistent with reduced neointimal proliferation and improved acute lumen gain in preclinical models, without the thrombosis penalty seen at high temperatures. The dual-balloon architecture is designed to hold the vessel wall inside that window while keeping luminal blood below thermal-injury thresholds. The peer-reviewed literature gives biological plausibility; efficacy in humans with the EVA™ device still has to be established in FIH / EFS studies.
Why thermal balloon angioplasty now
Right mechanism, right target, with the dose control the 1990s lacked
Radiofrequency and laser thermal balloons were tried in the early 1990s and largely set aside, so it is fair to ask why EVA revisits the approach. The earlier devices treated the wrong target with heat they could not control, and the means to bound the dose did not exist yet. Four things are different now.
Different disease
The 1990s devices heated primary atherosclerotic plaque in native arteries, where deep, uncontrolled injury drove more restenosis. EVA treats in-stent restenosis, the soft SMC-rich neointima inside an existing stent. The stent already holds the vessel open, so EVA does not need the aggressive remodeling dose those devices used.
Controlled dose
The earlier failure was a dosimetry failure: no real-time feedback, so the heat overshot into deep necrosis and thrombosis. EVA is built around a defined 50–70°C window, real-time thermistor and generator control, and a single sub-30-second pulse, validated in-silico and on the bench.
Protected blood and adventitia
Heating trapped or flowing blood was a major thrombosis driver. EVA's dual-balloon design isolates the segment and keeps luminal blood below 42°C, while the steep thermal gradient spares the adventitia.
No durable alternative
In the 1990s, stents and then drug-eluting stents solved primary disease, so thermal balloons were outcompeted. For ISR there is still no durable therapy; drug-coated balloons and drug-eluting stents only delay recurrence. The need EVA addresses barely existed when the approach was first tried.
Proposed mechanism of action in ISR
In plain terms: a brief, precise pulse of heat calms the unwanted tissue in-growth inside the stent and lets a healthy lining regrow. The biological detail:
- 1
Controlled thermal ablation of the luminal neointima, where the depth-dose gradient concentrates the highest temperature on the tissue narrowing the stent.
- 2
Extracellular-matrix modification : collagen denaturation reduces elastic recoil and improves dilation.
- 3
SMC apoptosis via heat-shock signaling : ↑HSP70, ↓Ki-67 proliferation index.
- 4
Suppression of the recurrent restenotic response : moderated collagen density after treatment.
- 5
Stent-scaffold advantage : mechanical support means deeper injury is less of a concern in fibrotic stenosis.
The most directly relevant ISR model
In a stented, atherosclerotic model of in-stent restenosis (Brasselet 2008), a controlled moderate thermal dose produced the largest lumen and the lowest restenosis, with reduced smooth-muscle proliferation and increased apoptosis, with no increase in thrombosis.
The biology behaves as the dose-dependence principle predicts, which is the effect EVA™ is designed to deliver. EVA™ targets a modestly higher wall temperature (~65°C) than this bare-vessel model's ~50°C optimum, because the indwelling stent scaffold shields the deeper vessel wall and the sub-30-second hold limits thermal spread, keeping the dose inside the same anti-proliferative, sub-thrombotic window. Confirming that margin, effective ablation without deep thermal injury, is a primary objective of the 2026 dose-ranging animal ISR program.
Safety by design · the thermal-dose window
Anti-proliferative benefit and risk both rise with dose, so EVA™ stays in the moderate band
Dose dependence is the unifying principle: every documented benefit of vascular heating, and every documented harm, scales with thermal dose (temperature × time × depth). Because dose falls off with depth, the effect is zoned: the luminal neointima at the top of the window is thermally ablated, the deeper wall sees a sub-lethal dose that favors SMC apoptosis and collagen compliance, and the adventitia stays below the injury threshold. A moderate dose favors apoptosis, compliance and anti-proliferation with intact re-endothelialization; an excessive dose adds deep necrosis, endothelial loss, tissue-factor expression and thrombosis.
The stent's job is to hold the vessel open with outward (radial) force, but tissue keeps growing back inside it. EVA™ is designed to work with the stent: to ablate the overgrown tissue and support re-endothelialization (a healthy new lining), with the goal that regrowth does not return inside the stent.
EVA works with the stent
The evidence base
Built on peer-reviewed preclinical and human data
In short: three decades of peer-reviewed work show that a controlled, moderate thermal dose is anti-proliferative and safe, while excessive heat is neither.
Brasselet 2008
Eur Heart J · stented atherosclerotic rabbit
The most directly relevant ISR model: moderate heating (~50°C) gave the largest lumen and lowest restenosis with no increase in thrombosis, plus reduced SMC proliferation, increased apoptosis, ↑HSP70, ↓collagen.
Fram 1993
JACC · porcine peripheral, in vivo
Establishes the acute lumen-gain mechanism (+22.9% vs +12.7% cross-sectional area vs cold dilation) and the safety dose window that scales with temperature and time.
Yamashita 1994
JACC · 32 patients, complex lesions
First-generation human RF thermal balloon: 82% acute success with no death, perforation or dissection, which established human feasibility and acute safety. Those first-generation devices were later abandoned on durability rather than acute safety: uncontrolled dosing drove restenosis, and drug-eluting stents outcompeted them for primary disease.
EVA™ engineering validation · in-silico + benchtop
Our R&D confirms the device can hit that dose window
The literature defines the target dose. Our own computational modeling and benchtop testing show the dual-balloon system delivers that dose accurately, with luminal blood kept below the caution threshold.
A Pennes bioheat finite-element model shows balloon temperatures of ~70°C bring the vessel wall to ~65°C, inside the 50–70°C therapeutic window, across the treatment zone over a 30-second hold, with diameter-specific targets from 4 to 8 mm.
The model keeps trapped luminal blood at the balloon ends below the 42°C caution threshold; on the bench the pocket region only reached ~42°C at 40s, which agrees with the model to within ~1°C.
A 6 mm balloon in a 37°C bath reproduced the model within <2°C in the treatment zone and <1°C in the safety-critical blood / pocket region.
EVA™ internal engineering and thermal-modeling work. Presented as engineering support, non-peer-reviewed, and not evidence of clinical efficacy.
The prototype
See the dual-balloon system on the bench
The working prototype performing a controlled inflation and the heated saline and contrast fill, the same behavior our in-silico model and benchtop testing confirmed.
EVA™ TBA prototype · bench demonstration
Dual-balloon inflation & heated saline + contrast fill
Peer-reviewed sources: Fram 1993 · Brasselet 2008 · Yamashita 1994, among others. EVA™ internal engineering and thermal-modeling work is non-peer-reviewed and clearly separated. No human efficacy data exist for the EVA™ device yet. Clinical effectiveness in humans remains a hypothesis to be tested in First-in-Human and Early Feasibility studies.
