An electrocardiogram, or EKG (also known as ECG), is a simple, non-invasive test that records the electrical activity of the heart. This procedure provides a visual representation of the heart’s rhythm, helping physicians detect potential issues like arrhythmias or signs of previous heart damage. While the standard practice involves the supine position (lying flat), circumstances sometimes require the test to be performed while sitting up, which can influence the final tracing.
Why the Supine Position is Standard
The standard practice for a diagnostic EKG involves the patient lying flat on their back, known as the supine position. This positioning is favored because it creates a consistent and reproducible baseline for the heart’s electrical signals. Lying down fully supports the body, encouraging muscle relaxation and minimizing involuntary movements, such as tremors, that can distort the recording.
Consistency is important in EKG testing, as results are often compared with previous tests or established reference ranges. The supine position ensures the heart is in a fixed anatomical location, allowing for consistent electrode placement, particularly for the V1–V6 chest leads. Changing body position can shift the heart and alter the electrical axis recorded on the tracing, which complicates interpretation.
When a Seated EKG is Necessary
While lying flat is the preferred standard, an EKG can be performed with the patient sitting up, and this is sometimes medically necessary. The seated position is an acceptable alternative when a patient cannot tolerate lying flat due to specific health issues. For example, patients with orthopnea (severe shortness of breath when reclining) must remain upright to breathe comfortably, often due to conditions like heart failure.
Other limitations, such as severe back pain, mobility issues, or extreme obesity that compromises breathing, also mandate a seated EKG. In these non-standard situations, the technician takes steps to ensure the best recording quality. This includes ensuring the patient sits still, rests their arms comfortably, and clearly documents the non-standard position on the EKG tracing.
How Sitting Up Affects EKG Interpretation
When an EKG is recorded in a seated position, it introduces potential changes that clinicians must consider during interpretation. The most common issue is the increased risk of an artifact, which is unwanted electrical noise not produced by the heart. Sitting upright can increase muscle tension, especially in the arms or back, leading to a muscle tremor artifact that appears as a rapid, irregular fluctuation on the baseline.
A change in posture also causes the heart to shift position slightly within the chest, altering the appearance of the electrical tracing. This positional change can result in a minor shift in the heart’s electrical axis or variations in the amplitude (height) of specific waveforms, such as the QRS complex. Sitting up may also increase the heart rate and decrease the voltage of certain leads. Cardiologists are trained to recognize these expected changes attributable to posture, provided the technician notes the non-standard position on the chart.