As the inventor of pacing technology, Dr. Paul Zoll, a founder of ZOLL Medical, performed the first human clinical cardiac pacing procedure in 1952. Today, the company named for him leads the way with patented external pacing technology that is incorporated into our AED and electrode products.

Why Pacing Matters

Pacing is a Class I intervention for symptomatic bradycardias (American Heart Association Guidelines 2005, V-69). Pacing is also used with a complete heart block.

How ZOLL Pacing Works

ZOLL defibrillators provide twice the capture at half the current; a 40-millisecond pulse with constant current is utilized. This means less patient discomfort.

Pacing Waveform Comparison

Pacing waveform comparison 

The ideal pacer current is the lowest value that maintains capture—usually about 10% above threshold. Typical threshold currents range from 40 to 80 milliAmps. 

ZOLL's constant current, 40-msec pulse overcomes disadvantages inherent in other external pacemakers.

Pacing technology design differences greatly impact capture rates and patient survival. Independent clinical studies and widespread use of ZOLL's patented pacing pulse has proven to be the most effective noninvasive technology available.    


  • 40-millisecond pulse width  
  • Constant electrical current  
  • Proprietary electrode design  
  • Distinctive capture recognition  
 Pacing waveform comparison 


ZOLL incorporates a unique technology in all of its professional defibrillators. Pressing and holding the 4:1 button temporarily withholds pacing stimuli, thereby allowing you to observe the patient’s underlying ECG rhythm and morphology without losing capture. When depressed, this button causes pacing stimuli to be delivered at one-fourth of the indicated ppm setting.

Proper pacing requires a reliable, high quality surface ECG signal.  ZOLL helps ensure proper pacing with OneStep™ Pacing electrodes or OneStep™ Complete electrodes. These hands-free therapy pads include both ECG monitoring and pacing/defibrillation electrodes in a single pad assembly. They provide reliable ECG monitoring without the need to use separate ECG leads.

Dunn, Gregory, Noninvasive temporary pacing: experience in a community hospital, Heart and Lung. 1989;18:23-28.

Clinton, E, Antman, Zoll PD, Zoll R.H., External noninvasive temporary cardiac pacing: clinical trials. Circulation. 1985;71:937-944.

Heller, et al. A comparative study of five transcutaneous pacing devices in unanesthetized human volunteers. Prehospital and Disaster Medicine. 1989;4:15-18.

Falk, Zoll PM, Zoll RH, Safety and efficacy of noninvasive cardiac pacing. New England Journal of Medicine. 1983;309:1166-1168.

Knowlton Falk, External cardiac pacing during in-hospital cardiac arrest. American Journal of Cardiology. 1986;57:1295-1298.

Related Products

R Series Defibrillators

R Series ALS Dashboard v2  

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M Series Defibrillator

M Series Defibrillator  

ZOLL M Series® defibrillators offer a family of products to meet your clinical needs from BLS to ACLS. Products range from AED and advisory defibrillator models to manual units and Critical Care Transport (CCT).

M Series CCT Defibrillator 

M Series CCT Defibrillator 

The M Series® CCT defibrillator features a three-channel display for ECG and up to two invasive pressures with ranges covering arterial, pulmonary arterial, central venous or intracranial pressure as well as two temperature channels.

Defibrillator Electrodes and Internal Paddles

Onestep CPR Complete Adult

It's about choice. ZOLL® offers the world's first line of resuscitation electrodes for every use and every patient.

E Series Defibrillator


The ZOLL® E Series® is ideal for emergency defibrillation as it is specifically designed to withstand the crash, tumble, and bounce environment of EMS.

X Series Monitor Defibrillator

X Series

The ZOLL X Series® is about half the size and half the weight of competitive full-featured monitor/defibrillators—but a lot more powerful.