Abnormalities Caused by Cardiac Pathology

- Abnormalities Caused by Cardiac Pathology (continued) Abnormality Description Paroxysmal atrial There is a common arrhythmia, usually seen in young adults with normal hearts. There are no tachycardia (PAT) visible P waves, because they are hidden by the T wave of the previous cycle. The atrial rate is 140—250 per minute. Premature atrial A P wave occurs earlier than expected, usually from a source outside the sinus node. Therefore, contractions (PACs) P waves are distorted. Premature ventricular The wide QRS complexes occur without preceding P waves, They may be caused by electrolyte contractions (PVCs) imbalance, stress, smoking, alcohol, or toxic reactions to drugs and in a majority of patients who have had a heart attack (Figure 50—18). l FIGURE 50-18 > Multifocal premature ventricular contractions (PVCs). Sinus arrhythmia Normally seen in children and young adults; all aspects of the ECG are normal except the irregularity. The space between QRS complexes is not equal. The heart rate increases on inspiration and decreases on expirationt (continued)