Bradygastrias and Mixed Dysrhythmias

Abstract

Bradygastrias are low-frequency electrogastrogram (EGG) waves that range from approximately 1.0 to 2.5 cycles per minute (cpm) . Some bradygastria waves are high amplitude and occupy the full scale of the EGG recording channel; others are very low amplitude and appear to be almost flatline. Bradygastrias have been recorded in patients with functional dyspepsia, diabetic and idiopathic gastropathy, and nausea of pregnancy. These patients have symptoms of abdominal discomfort, fullness, nausea, and vomiting. In this chapter, the causes of bradygastria patterns are reviewed and examples of bradygastrias are shown. EGGs also may have increased bradygastria and tachygastria waves, a pattern termed a mixed dysrhythmia. The exact origin of bradygastrias has been difficult to determine. In certain circumstances, the antrum contracts at 1.5 to 1.8 contractions per minute rather than the more recognized 3-per-minute contractions. Figure 8.1 indicates the relationship between EGG waves and low-frequency antral peristaltic contractions recorded from an intraluminal pressure sensing device during fasting and after infusion of erythromycin in healthy individuals. The antral contractions were recorded 3 and 1.5 cm from the pylorus. During fasting, 2-cpm EGG waves were present and correlated with 2-per-minute antral contractions. Each of these low-frequency contractions was associated with a low-frequency EGG wave (a negative deflection followed by a positive deflection). Irregular antral attractions also occur during fasting and may be reflected in the EGG as 1- to 2-cpm EGG waves. After erythromycin infusion, the EGG waves occurred at 1.0 to 1.5cpm and correlated with stronger antral contractions that occurred at the same frequency: 1.0 to 1.5 per minute. Thus, the bradygastria EGG frequencies correlated with the low-frequency antral contractions during fasting and after infusion of erythromycin. These studies indicate that, under certain conditions, bradygastria waves reflect low-frequency antral contractions. The fundus of the stomach normally contracts slowly at a rate from 0.5 to 1 contraction per minute.15 Thus, the low-frequency contractile activity of the fundus may also be reflected in the low frequency EGG signals in certain situations.