#12. Is ECG monitoring important in non-cardiac areas?

Hi, I am Dr. Nicola Cosentino. Welcome to this podcast series on ECG monitoring, sponsored by GE Healthcare. Today´s topic will be on ECG monitoring in non-cardiac areas.

Since the introduction of ECG monitoring in hospital units >60 years ago, the goals of monitoring have expanded from simple tracking of heart rate and basic rhythm to the diagnosis of complex arrhythmias, the detection of myocardial ischemia, and the identification of a prolonged QT interval. During the same six decades, major improvements have occurred in cardiac monitoring systems, including computerized arrhythmia detection algorithms, ST-segment/ischemia monitoring software, improved noise-reduction strategies, multi-lead monitoring, and reduced lead sets for monitoring-derived 12-lead ECGs with a minimal number of electrodes.

All these technical advances have led to the implementation of continuous ECG monitoring not only in cardiac and cardiac-surgery patients but also in a variety of other critical and non-critical care hospital settings. Notably, although cardiovascular complications in the acutely ill “non-cardiac” patients are small in number, they are associated with a high mortality and morbidity rate. This makes it essential for physicians to continuously monitor ECG in these patients.

In particular, continuous ECG monitoring should be recommended for:

• non-cardiac patients with major trauma
• acute respiratory failure
• sepsis
• shock
• acute pulmonary embolus
• major non-cardiac surgery (especially in older adult patients with a history of coronary artery disease or coronary risk factors)
• renal failure with electrolyte abnormalities (e.g. hyperkalaemia)
• drug overdose (especially from known arrhythmogenics, e.g., digoxin, tricyclic antidepressants, phenothiazines, antiarrhythmic).

The first goal of continuous ECG monitoring in these patients is to aid in immediate recognition of sudden cardiac arrest to improve time to defibrillation. In particular, nearly 2/3 of the life-threating ventricular arrhythmias ultimately leading to cardiac arrest occur unexpectedly (out of the blue, without the so-called warning arrhythmias), although most of them develop in patients with known cardiovascular disease. In addition, continuous ECG monitoring may help recognizing deteriorating arrhythmic conditions such as non-sustained arrythmias that may lead to a life-threatening arrhythmia. Of note, in all these acute “non-cardiac” patients, the chance of a new-onset arrhythmia can be high, as high as 1 patient out of 5.

However, there are other several goals of continuous ECG monitoring in these non-cardiac clinical settings. It may assist clinicians in early detecting any serious cardiac, respiratory, or neurologic impairment as assessed by the increase in heart rate or increase in ventricular ectopic beats. In the hospitalized patient, heart rate helps monitor deterioration and therapy response as patient’s heart rate increases before their arterial pressure drops so heart rate is vital to monitor continuously, especially in the acutely-ill patient.

Take, for example, gastrointestinal bleeding. In order to know if the patient needs to be transferred immediately for endoscopy, you look at vital parameters, mainly heart rate and arterial pressure, as well as arterial blood gases and hemoglobin levels. If we detect a progressive increase in heart rate, probably our patient is keeping bleeding and heart rate will tell us the presence of an active bleeding earlier than hemoglobin levels or arterial pressure drop. This notion can be actually applied to almost all hospitalized patients. Indeed, an old adage says: tachycardia, especially progressively increased tachycardia, is always a bad sign. Continuous ECG monitoring is not only complex arrhythmia and heart rate, it means also myocardial ischemia (ST-segment) and QTc interval. Any progressive change in ST-segment deviation or QT interval length can be detected earlier by continuous ECG monitoring before the “clinical picture becomes overt” and this will let us have more time to act or counteract the ongoing clinical issue. Indeed, hypoxia, arterial hypotension, or anemia may all lead to ST-segment changes (especially ST-segment depression) and/or QT interval prolongation. Therefore, in patients hospitalized for clinical reasons beyond acute cardiac issues, continuous ECG monitoring helps clinicians with arrhythmia detection and, probably more importantly, with clinical decision making by anticipating deterioration, evaluating if the therapy is working, and driving any further diagnostic tests.

Thank you for listening to this podcast on ECG monitoring in non-cardiac areas. The next podcast of this series will be on how to prioritize which patients should be monitored with ECG.

References:

Sandau KE, Funk M, Auerbach A, Barsness GW, Blum K, Cvach M, Lampert R, May JL, McDaniel GM, Perez MV, Sendelbach S, Sommargren CE, Wang PJ; American Heart Association Council on Cardiovascular and Stroke Nursing; Council on Clinical Cardiology; and Council on Cardiovascular Disease in the Young. Update to Practice Standards for Electrocardiographic Monitoring in Hospital Settings: A Scientific Statement From the American Heart Association. Circulation. 2017 Nov 7;136(19):e273-e344.

Drew BJ, Califf RM, Funk M, Kaufman ES, Krucoff MW, Laks MM, Macfarlane PW, Sommargren C, Swiryn S, Van Hare GF; American Heart Association; Councils on Cardiovascular Nursing, Clinical Cardiology, and Cardiovascular Disease in the Young. Practice standards for electrocardiographic monitoring in hospital settings: an American Heart Association scientific statement from the Councils on Cardiovascular Nursing, Clinical Cardiology, and Cardiovascular Disease in the Young: endorsed by the International Society of Computerized Electrocardiology and the American Association of Critical-Care Nurses. Circulation. 2004 Oct 26;110(17):2721-46.