Deep inspiration electrocardiogram test: physiologic mechanisms and diagnostic capabilities

The article reflects modern concepts about the effect of deep inspiration and breath holding on the heart functioning and the reflection of these processes at ECGs. Positional changes of Q waves, primarily in leads III and aVF, and their possible differences from pathological Q waves are described. Reflex and humoral effects of deep inspiration and breath holding on heart functions such as contractility, automatism and conductivity are considered. Examples of rhythm and conduction disturbances that rarely occur during breath holding are illutrated on ECGs. A recommended variant of the implementation of the deep inspiration ECG test using computer ECG systems is described, which implements continuous ECG recording on free breathing, during inspiration and while holding the breath. This version of the test does not change the operators’ complexity and time of ECG registration.