Closed Loop Stimulation

CLS supports physiological pacing

Closed Loop Stimulation (CLS)

A New Era of Physiological Pacing

At BIOTRONIK, we have pioneered some of the industry’s best solutions for increasing therapy effectiveness, streamlining clinic workflow and improving the quality of life for patients. One of these is Closed Loop Stimulation (CLS), a unique physiological rate-adaptive technology.

How does CLS pace physiologically?

CLS is integrated into the natural cardiovascular control system and determines the appropriate heart rate based on continuous intracardiac impedance measurements. These measurements reflect changes of the cardiac contraction dynamics in reaction to information coming directly from the autonomic nervous system.

Cardiac output is the product of heart rate and stroke volume. Cardiac output is "monitored" by the autonomic nervous system via the mean arterial blood pressure. Changes in the mean arterial blood pressure influence the information coming from the autonomic nervous system, and thus have an effect on the heart rate and contraction dynamics of the myocardium, resulting in the adaptation of the cardiac output to current metabolic demand.

In patients with chronotropic incompetence or other dysfunctions of the sinus node, CLS monitors the contraction dynamics and translates them into proper heart rate adaptation, thus delivering proven physiological therapy. By doing so, CLS emulates the healthy sinus node providing optimal heart rates under every circumstance, even during mental activity - a feature unique to BIOTRONIK.


What BIOTRONIK devices are equipped with CLS?

CLS is available across the full portfolio of BIOTRONIK therapeutic cardiac devices:

  • Bradycardia therapy: Pacemakers - SR-T and DR-T
  • Tachycardia therapy: Implantable Cardiac Defibrillators (ICDs) - VR-T, DR-T and DX
  • Cardiac resynchronization therapy: CRT-D and CRT-P

Frequently Asked Questions

  • Are special leads required for CLS to work? No, CLS's proper functioning does not depend on the type or fixation position of the lead. Every unipolar or bipolar lead with passive or active fixation is compatible, as long as the lead is positioned in the right ventricle.
  • Can CLS be used in combination with beta blockers? CLS uses a rolling average of the previous 256 resting curves and therefore can quickly and effectively react to changes in the contraction dynamics. Beta-blockers exert an influence on basic contractility and consequently update the reference curve, delivering optimal rate modulation.
  • What about CLS in combination with vasovagal syncope? CLS has been proven to be very effective for patients with vasovagal syncope. Due to the early increase in contractility just before the syncopic event, CLS is able to immediately increase the heart rate, preventing rate drop, which is usually the cause of a vasovagal syncope.
  • What about changes in basic contractility (e.g. DCM, infections, AMI)? The reference curve adapts to the changed state in basic contractility and calibrates CLS automatically to suit these circumstances.