Fragmented QRS complex has poor sensitivity in detecting myocardial scar.

Objective: To study the association of the fragmented QRS complex versus the Q wave with myocardial scar and viability.

Background: A prior study has suggested that the fragmented QRS complex on an electrocardiogram (ECG) is a highly sensitive and specific marker of myocardial scar as detected by regional perfusion abnormalities on a nuclear stress test. There is no external validation of this data.

Dysrhythmias of the respiratory oscillator.

Breathing is regulated by a central neural oscillator that produces rhythmic output to the respiratory muscles. Pathological disturbances in rhythm (dysrhythmias) are observed in the breathing pattern of children and adults with neurological and cardiopulmonary diseases. The mechanisms responsible for genesis of respiratory dysrhythmias are poorly understood.