CCT (CCI) key terms

Infection-control steps used for every patient because any blood or body fluid may carry disease. They include hand hygiene and gloves, plus gown, mask, or eye protection when splashes are likely.

A small adhesive pad with conductive gel that sticks to the skin and detects the heart's electrical signal, passing it through a wire to the ECG machine or monitor.

Explaining a test's purpose, risks, benefits, and alternatives so the patient can decide freely whether to proceed. The patient must be alert enough to understand and ask questions.

Placing the six chest electrodes V1 to V6 at specific rib spaces and body landmarks so the tracings are consistent and can be compared between patients and over time.

Attaching electrodes to the right arm, left arm, right leg, and left leg at consistent spots such as wrists and ankles; these four electrodes create the six frontal-plane leads.

Any signal on the ECG that does not come from the heart, such as muscle movement, poor electrode contact, or nearby electrical devices. It can imitate or hide a real rhythm.

Jittery, high-frequency noise caused by shivering or muscle tension. It thickens the tracing and can hide small waves such as P waves or fibrillatory activity.

A slow, rolling drift of the baseline up and down, often from breathing, sweating, or loose electrodes. It makes measuring wave heights and ST segments unreliable.

Adjusting the ECG machine so that one millivolt of electrical signal produces a deflection ten millimeters tall. A square calibration mark at the start confirms the setting.

How fast the ECG paper moves, usually 25 millimeters per second. At that speed one small box is 0.04 seconds and one large box is 0.20 seconds.

The first small deflection of a normal beat, caused by the atria depolarizing. It is normally upright in lead II and less than 0.12 seconds wide.

The time from the beginning of the P wave to the beginning of the QRS complex, normally 0.12 to 0.20 seconds. It shows how well the AV node conducts.

The tall, sharp deflection produced when the ventricles depolarize. A normal QRS is narrow, less than 0.12 seconds; a wider one suggests delayed ventricular conduction.

The time from the start of the QRS to the end of the T wave, covering ventricular depolarization and repolarization. It shortens as heart rate rises and is often corrected for rate.

The section between the J point and the start of the T wave. It is normally flat; elevation or depression can mean acute injury or reduced blood flow to the heart muscle.

The junction where the QRS complex ends and the ST segment begins. Technicians use it as the reference point for measuring ST elevation or depression.

The wave after the QRS that reflects the ventricles recovering electrically. It is usually upright in most leads and may flatten, invert, or peak with ischemia or electrolyte imbalance.

The main direction of ventricular depolarization as seen from the front of the body, estimated from the limb leads. A normal axis points down and toward the patient's left.

A delay or block in one of the two main bundles carrying the impulse to the ventricles. It widens the QRS to 0.12 seconds or more and often gives it a notched shape.

Swapping limb or chest electrodes by mistake, which makes the tracing look abnormal, such as an upside-down P wave in lead I. Spotting it prevents a healthy heart being called diseased.

The heart's normal rhythm, started by the sinoatrial node. It shows a consistent upright P wave in lead II before each QRS and a rate between 60 and 100 beats per minute.

An early beat that starts in the atria outside the sinus node. Its P wave often looks different from the normal one, and the following QRS is usually narrow.

An early beat that starts in the ventricles, so it has a wide, odd-looking QRS with no P wave before it. A pause usually follows before the next normal beat.

A chaotic atrial rhythm with no true P waves, an irregularly irregular ventricular rate, and a wavy baseline. It raises stroke risk and often requires blood thinners.

A fast, organized atrial rhythm that makes a regular sawtooth pattern instead of P waves, usually near 300 atrial beats per minute. The AV node lets only some impulses reach the ventricles.

A run of three or more ventricular beats faster than 100 per minute, producing wide QRS complexes. It can be brief or sustained and may worsen into a life-threatening rhythm.

Disorganized electrical chaos in the ventricles with no usable QRS complexes and no effective pumping. It is a cardiac arrest rhythm that needs immediate CPR and defibrillation.

A consistent slowing of conduction through the AV node so the PR interval is longer than 0.20 seconds, while every P wave still produces a QRS complex.

Complete failure of impulses to pass from atria to ventricles, so P waves and QRS complexes occur independently at their own rates. The slow ventricular rate can cause dizziness or fainting.

A portable recorder worn for 24 to 48 hours that continuously records the ECG while the patient does normal activities. It is used to catch intermittent arrhythmias or silent ischemia.

A small recorder the patient turns on when symptoms occur, saving a short ECG strip. It is worn longer than a Holter and suits symptoms that happen only now and then.

A tiny device placed under the skin that watches the heart rhythm for months to years and saves abnormal events for the doctor to review later.

A log in which the patient records the time of symptoms, activities, and medications during ambulatory monitoring, letting the reviewer match complaints to the recorded rhythm.

An ECG recorded while the patient walks on a treadmill or pedals a bike against increasing resistance, looking for ischemia, arrhythmias, or abnormal blood pressure responses.

A common treadmill protocol with stages of three minutes each in which speed and incline rise steadily, so most patients reach maximal effort within a predictable time.

A unit for the energy cost of an activity compared with resting quietly, where 1 MET is the body's oxygen use at rest. Stress test workloads are often reported in METs.

The heart rate a patient should reach during a maximal test, often estimated as 85 percent of 220 minus age. Falling short may reflect poor effort, medications, or disease.

An abnormal failure of the heart rate to rise as expected during exercise, often defined as not reaching 85 percent of the age-predicted maximum despite real effort.