Advice

Technology overview

Technology overview

This briefing describes the regulated use of the technology for the indication specified, in the setting described, and with any other specific equipment referred to. It is the responsibility of healthcare professionals to check the regulatory status of any intended use of the technology in other indications and settings.

About the technology

CE marking

ThermoCool SmartTouch is a class III medical device. The manufacturer, Biosense Webster, has a CE certification dated November 2015 that includes the following catheters:

  • ThermoCool SmartTouch bi‑directional catheter, first CE marked in December 2010.

  • ThermoCool SmartTouch uni‑directional catheter, first CE marked in February 2011.

  • ThermoCool SmartTouch SF uni- and bi‑directional catheters, first CE marked in May 2014.

ThermoCool SmartTouch catheters require the CARTO 3 navigation system to visualise the contact force information. Biosense Webster was awarded a CE mark for the CARTO 3 system as a class IIa device in November 2008.

The current certifications for ThermoCool SmartTouch and the CARTO 3 navigation system expire in May 2017 and January 2018 respectively.

Description

ThermoCool SmartTouch is a flexible catheter with a deflectable distal section and a contact force sensor at the tip which is indicated for use in cardiac electrophysiological mapping (stimulation and recording) and cardiac ablation to treat supraventricular arrhythmias, including atrial fibrillation. It provides a real‑time measurement of the contact force applied by the catheter tip to a patient's heart wall during an ablation procedure, using a precision spring. This is designed to give clinicians more control than with a standard catheter by monitoring and modifying the applied force in order to create more effective scar tissue, and prevent accidental damage, during ablation procedures.

ThermoCool SmartTouch is a single‑use device with an overall length of 115 cm. Two types of ThermoCool SmartTouch catheter are available, with either a uni‑directional tip (available with deflectable distal curves of 73.5 mm, 84.5 mm or 98.5 mm) or a bi‑directional tip (available with symmetrical deflectable distal curves of 73.5 mm, 84.5 mm or 98.5 mm and asymmetrical deflectable distal curves of 73.5 mm/84.5 mm or 84.5 mm/98.5 mm). The catheters comprise several parts:

  • A deflectable distal section containing several electrodes, including a 3.5 mm tip electrode. All of the electrodes may be used for stimulating and recording (required for electrophysiological mapping) so a separate cardiac mapping catheter is not needed when using ThermoCool SmartTouch for ablation. The tip electrode also delivers the radiofrequency current to the desired ablation site and is irrigated. The catheter shaft measures 7.5 Fr with 8 Fr ring electrodes.

  • A hand‑piece that controls the movement of the catheter and the uni‑directional or bi‑directional tip deflection. Tip deflection is controlled at the proximal end by a thumb‑knob on the hand‑piece. The shaft controls the plane of the curved catheter tip allowing it to be rotated for accurate positioning.

  • A thermocouple temperature sensor embedded in the tip electrode.

  • A location sensor and transmitter coil embedded in the distal section that sends location signals to the CARTO 3 navigation system.

  • A precision spring embedded in the distal section that flexes in response to contact force, enabling software calculation of force in grams.

  • A saline input port with a standard luer fitting at the proximal end of the catheter. This allows the injection of normal saline to irrigate and cool the tip electrode and ablation site during the ablation phase of the procedure.

In addition to the standard ThermoCool SmartTouch catheter, the company has produced an 'SF' (surround flow) variant with a modified irrigation tip. This is CE marked but not yet commercially available in the UK.

Additional components needed for the ablation procedure include:

  • The CARTO 3 navigation system, with SmartTouch 3D software module and integrated display screen, designed to visualise the real‑time calculated position and orientation of the catheter within the patient's heart. This may already be in use in a cardiac catheterisation laboratory.

  • A compatible radiofrequency generator, such as the SMARTABLATE radiofrequency generator (Stockert Medical Solutions) or the Stockert EP Shuttle Generator (Stockert Medical Solutions).

  • A compatible irrigation pump and irrigation tubing, such as the COOLFLOW irrigation pump (Biosense Webster) or the SMARTABLATE irrigation pump and tubing set (Stockert Medical Solutions), which connects to the catheter saline port's luer fitting.

  • An introducer sheath with a minimum diameter of 8.5 Fr to insert the catheter into a large central blood vessel, usually the femoral vein.

  • Six disposable dispersive pads and an earthing pad which complete the ablation circuit. These are usually attached to the patient's chest, back and leg.

ThermoCool SmartTouch is inserted through the introducer sheath and manually moved through the blood vessels in order to map the site of the abnormal heart rhythm. Fluoroscopy and electrocardiograms are used to aid catheter positioning. When the site is identified, the same ThermoCool SmartTouch catheter is used to carry out the ablation and deliver radiofrequency energy. This blocks the electrical path that causes the abnormal heart rhythm. Biosense Webster does not specify a target contact force or a force range for an ablation procedure. ThermoCool SmartTouch transmits contact force information to the clinician throughout the procedure using the CARTO 3 navigation system (which is commonly used in electrophysiology). ThermoCool SmartTouch is also used to confirm entrance and exit block of the electrical impulse (that is successful PVI) during the procedure. The catheter is removed after treatment. In some cases the clinician may prefer to use a separate mapping catheter to identify the site of the abnormal heart rhythm and confirm electrical isolation of the pulmonary veins. A separate mapping catheter can be used simultaneously, sequentially or interchangeably with ThermoCool SmartTouch.

Setting and intended use

ThermoCool SmartTouch would be used in a cardiac catheterisation laboratory during percutaneous PVI. It would be used by cardiac electrophysiologists trained in cardiac ablation who have appropriate training on ThermoCool SmartTouch. The procedure is usually done with the patient under local anaesthesia and sedation, although PVI can also be done under general anaesthesia according to patient or centre preference.

ThermoCool SmartTouch and its additional components are indicated for catheter‑based cardiac ablation when used with a compatible radiofrequency generator, and also for cardiac electrophysiological mapping.

Contraindications for use are similar to other cardiac ablation catheters, and include: cardiac surgery within previous 8 weeks; artificial heart valves; active systemic infection; use in coronary vasculature; myxoma (a heart tumour) or intracardiac thrombus (blot clot); trans‑septal atrial approach in patients with an interatrial baffle or patch; retrograde trans‑aortic approach in patients with aortic valve replacement; and use with an introducer sheath of less than 8.5 Fr.

Current NHS options

NICE guidance on the management of atrial fibrillation recommends offering people a personalised care package of information and prompt referral for specialised management if treatment fails to control symptoms at any stage. Recommended interventions include anticoagulation medications to reduce the risk of stroke, and heart rate and rhythm control (antiarrhythmic) medications or electrical cardioversion. Left atrial catheter ablation is recommended for people with paroxysmal atrial fibrillation, and considered in people with persistent atrial fibrillation, in whom drug treatment has failed to control their symptoms or is unsuitable. NICE interventional procedures guidance on percutaneous radiofrequency ablation states that the evidence for the safety and efficacy of this treatment for atrial fibrillation is adequate to support its use in appropriately selected patients, provided that normal arrangements are in place for audit and clinical governance. The guidance also states that clinicians should ensure that patients fully understand the potential complications, the likelihood of success and the risk of recurrent atrial fibrillation associated with this procedure. The guidance further recommends that the procedure should only be done in specialist units and with arrangements for cardiac surgical support in the event of complications, and should only be done by cardiologists with extensive experience of other types of ablation procedures. Other cardiac ablation procedures are described in related interventional procedures guidance (see relevance to NICE guidance programmes). Other available interventions include surgical lesions (by sternotomy, thoracoscopy or minimally invasive approaches) used alone or in combination with valve or revascularisation surgery to control heart rate.

NICE is aware of the following CE‑marked devices that appear to fulfil a similar function to ThermoCool SmartTouch (and its additional components):

NICE has produced a medtech innovation briefing on the TactiCath Quartz catheter.

Costs and use of the technology

Biosense Webster has provided the following list prices (excluding VAT).

Each single‑use ThermoCool SmartTouch costs £1,675 (uni‑directional) or £1,750 (bi‑directional).

This equipment is needed for mapping and ablation procedures using the ThermoCool SmartTouch catheter:

  • CARTO 3 navigation system: £129,999

  • CARTO 3 SmartTouch module: £35,000

  • CARTO 3 system external reference patches (pack of 6): £595.

An introducer sheath greater than 8.5 Fr (not supplied by Biosense Webster) is also needed.

These costs can be reduced for customised NHS contracts depending on volume and contract duration, and local arrangements.

ThermoCool SmartTouch can only be used with Biosense Webster radiofrequency generators, such as the SMARTABLATE system with integrated irrigation pump (£35,000) or the Stockert EP Shuttle radiofrequency generator used with the separate COOLFLOW irrigation pump (£14,999 and £8,999 respectively). These components could be used for other ablation procedures and may already be present in some cardiac catheterisation laboratories.

ThermoCool SmartTouch ablation catheters are single‑use and have an anticipated shelf‑life of 12 months. The anticipated lifespan of the CARTO 3 navigation system, COOLFLOW irrigation pump and SMARTABLATE system are 7 years, 10 years and 10 years, respectively.

Biosense Webster offers a number of service contracts for hardware covering 1, 2 or 3 years, which cost:

  • CARTO 3 navigation system: £12,000, £23,000, £32,000

  • Stockert EP Shuttle: £500, £800, £900

  • COOLFLOW irrigation pump: £900, £1,600, £2,100.

The manufacturer provides onsite training by a clinical support specialist as part of the overall service, at no cost.

Likely place in therapy

ThermoCool SmartTouch would be used in people diagnosed with symptomatic atrial fibrillation when drug treatment has failed to control their symptoms (NICE guidance on the management of atrial fibrillation). It would replace conventional radiofrequency ablation catheters without contact force‑sensing technology, which are typically used with a separate mapping catheter. The overall care pathway would not be changed.

Specialist commentator comments

All 4 specialist commentators highlighted that the degree of contact between tissue and catheter is critical in for successful pulmonary vein isolation. One specialist commentator noted that real‑time dynamic contact force feedback during cardiac ablation procedures would enable operators to adjust catheter position, improve procedure efficacy and increase safety by avoiding the application of excessive force. One specialist commentator noted that the consistent message from general published evidence is that contact force‑guided ablation results in better isolation of the pulmonary veins, and improvement in clinical outcomes in addition to other surrogates such as procedure time and radiation dose, when compared with non‑contact force‑guided ablation.

A reduction in fluoroscopy time was highlighted as being important by another specialist commentator given the hazards associated with ionising radiation to both patients and operators.

One specialist commentator highlighted that the main difference between ThermoCool SmartTouch and previous navigation catheters is the ability to visualise the shaft electrodes using the CARTO 3 navigation system. This allows a representation of part of catheter to be seen within the mapping system and contributes to the reduced need for fluoroscopy during catheter manipulation.

One specialist commentator highlighted that contact force capability should allow more effective and safer ablation of complex arrhythmia substrates, and should not be restricted to treating atrial fibrillation.

One specialist commentator stated that contact force is 1 of several variables that affect ablation delivery. Cardiac perforation has been shown with force above 40 g; however, energy delivery not only involves contact force but also ablation time and radiofrequency power output. Tissue thicknesses differ between different areas of the atrium and the atrium is surrounded by structures such as the oesophagus posteriorly which may be particularly sensitive to heating. The specialist commentator noted that some data exists which may define efficacy, but none currently exists to define a safe contact force range. Another commentator agreed that what constitutes good contact and sufficient force is less well defined in the literature.

One specialist commentator advised that most centres in which atrial fibrillation ablation is done are within teaching hospitals, and being able to directly observe the force a trainee is exerting (during an ablation procedure) is invaluable but unlikely to be measured in a clinical trial.

The manufacturer states that the patient having had a ventriculotomy or atriotomy within the preceding 4 weeks and the presence of a prosthetic valve are contraindications for using ThermoCool SmartTouch. However, 1 specialist commentator indicated that these patient groups may need ablation treatment for arrhythmias, and that using a contact force‑recording catheter in these patients is advantageous.

One specialist commentator highlighted that the 2 randomised trials only report early reconnection, but contact force technology is important not just to improve early reconnection rates but also to minimise late reconnection. This requires the integration of other variables than contact force into ablation delivery. A second specialist commentator also indicated that although not all of the identified studies show an improvement in outcomes, the consistent message from the published data is that ablation guided by contact force results in better isolation of the pulmonary veins.

Equality considerations

NICE is committed to promoting equality, eliminating unlawful discrimination and fostering good relations between people with particular protected characteristics and others. In producing guidance, NICE aims to comply fully with all legal obligations to:

  • promote race and disability equality and equality of opportunity between men and women

  • eliminate unlawful discrimination on grounds of race, disability, age, sex, gender reassignment, marriage and civil partnership, pregnancy and maternity (including women post‑delivery), sexual orientation, and religion or belief (these are protected characteristics under the Equality Act 2010).

The risk of atrial fibrillation increases with age, and is more common in men than women. PVI catheter ablation is typically done under fluoroscopy guidance and therefore not recommended in people who are pregnant. Age, sex and pregnancy are protected characteristics under the Equality Act 2010.