Non infarction Q waves

Non infarction Q waves
Precise guide for Allied Health Science Students especially cardiac specialty students, DGNM, B.Sc Nursing & M.Sc Nursing Students regarding Non Infarction Q waves

1. NON INFARCTION Q WAVE Mr. Aby Thankachan,M.Sc (N), Ph.D Asst Professor HICON, CBE

2. Q WAVE 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. 

3. Abnormalities of the Q waves are mostly indicative of myocardial infarction. The terms “Q wave myocardial infarction” and “non-Q wave myocardial infarction” are earlier designations of different types of MIs ultimately resulting in, respectively, Q wave development or the absence of Q wave development. Loss of electromotive force associated with myocardial necrosis contributes to R wave loss and Q wave formation in MI.

4. This mechanism of Q wave pathogenesis, however, is not specific for coronary artery disease with infarction. Any process, acute or chronic, that causes sufficient loss of regional electromotive potential can result in Q waves. For example, replacement of myocardial tissue by electrically inert material such as amyloid (abnormal fibrous, extracellular, proteinaceous deposits found in organs and tissues)or tumor can cause Non infarction Q waves

5. A variety of cardiomyopathies associated with extensive myocardial fibrosis can cause pseudoinfarction patterns. Ventricular hypertrophy also can contribute to the appearance of Q waves. Q waves simulating the ECG pattern of coronary artery disease can be related to one (or a combination) of the following four factors physiologic or positional variants, altered ventricular conduction, ventricular enlargement, and myocardial damage or replacement.

6. Prominent Q waves can be associated with a variety of positional factors that alter the orientation of the heart . Depending on the electrical axis, prominent Q waves (as part of QS- or QR-type complexes) can appear in the limb leads ( aVL with a vertical axis and III and aVF with a horizontal axis). The axis of the ECG is the major direction of the overall electrical activity of the heart . It can be normal, leftward (left axis deviation, or LAD), rightward (right axis deviation, or RAD) or indeterminate (northwest axis).

7. An intrinsic change in the sequence of ventricular depolarization can lead to pathologic, noninfarct Q waves. The two most important conduction disturbances associated with pseudoinfarction Q waves are LBBB and the Wolff-Parkinson-White (WPW) preexcitation patterns. Wolff-Parkinson-White syndrome in which an extra electrical pathway in the heart causes a rapid heartbeat.