"Flat" ElectroCardioGram -

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  • Ten-year-long study reveals what happens when a person dies after heart failure, according to our partner The Conversation.

  • It aimed to find out whether it is possible for the heart to restart on its own, without any intervention such as cardiopulmonary resuscitation and without the administration of drugs.

  • The analysis of this study was carried out by Amanda van Beinum, doctoral student in sociology at Carleton University (Ottawa, Canada) and Sonny Dhanani, lecturer in pediatrics at the Faculty of Ottawa (Canada).

How long do doctors have to wait after a "flat line" appears before they can declare a person dead?

How can they be sure that the heartbeat and blood flow will not return?

The most common way to die is by heart failure.

However, there is little evidence of how long it takes to be dead after the heart stops beating.

This lack of information has implications for clinical practice and organ donation.

A fundamental principle of organ donation is the deceased donor rule: a donor must be dead before their organs can be harvested, and organ donation must not be the cause of their death.

The lack of data on how long to wait before declaring death creates stress: if doctors wait too long after the heart stops, organ quality begins to decline.

On the other hand, if we act too quickly, we risk recovering the organs before death actually occurs.

New studies show that heart activity doesn't always end when the line onscreen goes flat © Shutterstock (via The Conversation)

Our interdisciplinary team of physicians, bioengineers and clinical research specialists have spent the past ten years studying what happens when a person dies after heart failure.

We focused on critical care patients who died after disconnecting life support devices, as these people may be eligible for organ donation.

In particular, we wanted to know if it is possible for the heart to restart on its own, without any intervention such as cardiopulmonary resuscitation (CPR) and without the administration of drugs.

Heart failure up close

Our recent study, published in the

New England Journal of Medicine

, presents observations on the course of death in 631 patients in Canada, the Czech Republic and the Netherlands who died in an intensive care unit.

All the families of the patients consented to participate in the research.

In addition to collecting medical information on each person, we have developed a computer program that captures and observes heart rate, blood pressure, blood oxygenation level and respiratory profile directly from from bedside monitors.

We were thus able to analyze the course of the end of life of 480 out of 631 patients and to determine, among other things, if and when circulatory or cardiac activity returned after an arrest of at least one minute.

This video shows that blood pressure and EKG signals stop for 64 seconds before resuming, finally stopping almost three minutes later.

Video is accelerated eight times

It turns out that the appearance of the flat line is not a sufficient indicator.

We have observed that cardiac activity often stops and restarts several times during a normal dying process.

Of the 480 flat signals examined, we found a stop and restart pattern in 67 cases (14%).

The longest time the heart stopped before restarting on its own was four minutes and 20 seconds.

The longest time that heart activity continued after a restart was 27 minutes, but most only lasted a second or two.

None of the patients we observed survived or regained consciousness.

Our “Organ donation” file

We also found that it was common for the heart to continue to have electrical activity long after the circulation or pulse stopped.

The human heart works by electrical stimulation of the nerves which causes the heart muscle to contract and contributes to blood circulation, that is, the pulse that is felt in the arteries and veins.

We observed that the heartbeat (the electrical stimulation that causes the heart muscle to move) and the pulse (blood flow through the veins) stop simultaneously in only 19% of patients.

In some cases, the electrical activity of the heart continued for more than 30 minutes after the blood flow stopped.

Why seek to understand death

The results of our study are important for several reasons.

First, the fact that stopping and restarting cardiac activity and circulation are often part of the natural process of dying can be reassuring for doctors, nurses and people at the bedside.

Intermittent signals from monitors can be alarming if observers interpret them as signs of an unexpected return to life.

Our study provides evidence that shutdowns and restarts are to be expected during a normal dying process without resuscitation, and that they do not lead to regaining of consciousness or survival.

Resumption of signals: cardiac activity stops and begins again during the natural process of dying © A. van Beinum & S. Dhanani (via The Conversation)

Second, our observation that the longest pause before heart activity resumed on its own was four minutes and twenty seconds supports the current practice of waiting five minutes after stopping circulation before declaring death and proceed with organ recovery.

This helps demonstrate to organ donation organizations that their death certification practices are safe and appropriate.

Our results will be used to better inform policies and guidelines for the practice of organ donation in different countries.

In order for the donation system to work, you have to be sure that if someone has been declared dead, then they really are.

Trust enables families to choose donation in a time of mourning and the medical community to ensure safe and adequate end-of-life care.

Our "Death" file

This study is also important for improving our understanding of the natural course of death.

We have shown that it is not always so easy to determine when you can consider someone to be really dead.

This requires careful observation and close physiological monitoring of the patient.

Also, be aware that just like with life, the process of dying can take many forms.

Our work is a step towards realizing the complexity of death and allows us to see that it is necessary to go beyond the simple flat line to detect the moment when death has occurred.


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This analysis was written in English by Amanda van Beinum, doctoral student in sociology at Carleton University (Ottawa, Canada) and Sonny Dhanani, lecturer in pediatrics at the Faculty of Ottawa (Canada).

It was co-authored by Laura Hornby, Research Director and Consultant at the Children's Hospital of Eastern Ontario Research Institute and Canadian Blood Services, and Nathan Scales, Biomedical Engineer and Associate research at the Dynamic Analysis Laboratory of the Ottawa Hospital Research Institute

The original article was translated and published on The Conversation website.

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