What does the Q wave represent?

INTRODUCTION. By definition, a Q wave on the electrocardiogram (ECG) is an initially negative deflection of the QRS complex. Technically, a Q wave indicates that the net direction of early ventricular depolarization (QRS) electrical forces projects toward the negative pole of the lead axis in question.

What are the different types of ECG electrodes?

Two types of electrodes in common use are a flat paper-thin sticker and a self-adhesive circular pad. The former are typically used in a single ECG recording while the latter are for continuous recordings as they stick longer.

What is pseudo ECG?

Pseudo-electrocardiogram (ECG) were generated from the propagation of electrical signals in tissue slabs undergoing active mechanical deformation.

Which leads have Q waves?

Small Q waves are present in the left precordial leads in more than 75 percent of normal subjects. They are seen most frequently in lead V6, less frequently in leads V5 and V4, and rarely in V3. Q waves in these leads are present more often in young subjects than in subjects older than 40 years.

What causes Q waves on ECG?

Pathologic Q waves are a sign of previous myocardial infarction. They are the result of absence of electrical activity. A myocardial infarction can be thought of as an elecrical ‘hole’ as scar tissue is electrically dead and therefore results in pathologic Q waves.

What is Q wave infarction?

Q wave myocardial infarction refers to myocardial infarctions that in a Q wave forming on the 12-lead ECG once the infarction is completed.

When do Q waves appear?

Electrocardiogram Interpretation Q waves represent the initial phase of ventricular depolarization. They are pathologic if they are abnormally wide (>0.2 second) or abnormally deep (>5 mm). Q waves that are pathologically deep but not wide are often indicators of ventricular hypertrophy.

How do you find Q waves on an ECG?

The Q wave is the first downward deflection after the P wave and the first element in the QRS complex. When the first deflection of the QRS complex is upright, then no Q wave is present. The normal individual will have a small Q wave in many, but not all, ECG leads.

Does depolarization of the sinoatrial node cause deflection on the ECG?

One does NOT see any deflection on the ECG during the time that the sinoatrial node is being depolarized. The depolarization of the atrioventricular node and the His-Purkinje system also does not generate any electrical activity that is detectable in the ECG.

Where does depolarization occur on an electrocardiogram?

Electrocardiogram Depolarization occurs in the four chambers of the heart: both atria first, and then both ventricles. The sinoatrial (SA) node on the wall of the right atrium initiates depolarization in the right and left atria, causing contraction, which corresponds to the P wave on an electrocardiogram.

How to test the ECG electrode performance?

In order to test the ECG electrode performance, several laboratory tests have been performed on a high protective coating, a 70 μm thick polyurethane layer, and onto an ARMCO iron sample coated with a layer of thick corrosion products.

Does the depolarization of the atrioventricular node generate electrical activity?

The depolarization of the atrioventricular node and the His-Purkinje system also does not generate any electrical activity that is detectable in the ECG. One does not necessarily see a Q-wave or an R-wave or an S-wave in each lead that one examines.