High-resolution (HR) mapping has been used to study gastric slow-wave activation; however, the specific characteristics of antral electrophysiology remain poorly defined. This study applied HR mapping and computational modeling to define functional human antral physiology. HR mapping was performed in 10 subjects using flexible electrode arrays (128-192 electrodes; 16-24 cm) arranged from the pylorus to mid-corpus. Anatomical registration was by photographs and anatomical landmarks. Slow-wave parameters were computed, and resultant data were incorporated into a computational fluid dynamics (CFD) model of gastric flow to calculate impact on gastric mixing. In all subjects, extracellular mapping demonstrated normal aboral slow-wave propagation and a region of increased amplitude and velocity in the prepyloric antrum. On average, the high-velocity region commenced 28 mm proximal to the pylorus, and activation ceased 6 mm from the pylorus. Within this region, velocity increased 0.2 mm/s per mm of tissue, from the mean 3.3 ± 0.1 mm/s to 7.5 ± 0.6 mm/s (P < 0.001), and extracellular amplitude increased from 1.5 ± 0.1 mV to 2.5 ± 0.1 mV (P < 0.001). CFD modeling using representative parameters quantified a marked increase in antral recirculation, resulting in an enhanced gastric mixing, due to the accelerating terminal antral contraction. The extent of gastric mixing increased almost linearly with the maximal velocity of the contraction. In conclusion, the human terminal antral contraction is controlled by a short region of rapid high-amplitude slow-wave activity. Distal antral wave acceleration plays a major role in antral flow and mixing, increasing particle strain and trituration.
Resection of the gastric pacemaker during LSG acutely resulted in aberrant distal ectopic pacemaking or bioelectrical quiescence. Ectopic pacemaking can persist long after LSG, inducing chronic dysmotility. The clinical and therapeutic significance of these findings now require further investigation.
Optogenetics as developed by Dr. Karl Deisseroth and others has been a transformative technology in the area of neuroscience. By stimulating genetically-modified neurons with visible light, modulation of the ionic conduction across the cell membrane can be achieved with very high specificity and precise temporal control. Despite the major influence of this technique, its scope is limited by its invasive nature and its lack of stimulation depth.
Background
Gastric slow waves regulate peristalsis, and gastric dysrhythmias
have been implicated in functional motility disorders. To accurately define
slow wave patterns, it is currently necessary to collect high-resolution
serosal recordings during open surgery. We therefore developed a novel
gastric slow wave mapping device for use during laparoscopic procedures.
Methods
The device consists of a retractable catheter constructed of a
flexible nitinol core coated with Pebax. Once deployed through a 5 mm
laparoscopic port, the spiral head is revealed with 32 electrodes at 5 mm
intervals. Recordings were validated against a reference electrode array in
pigs and tested in a human patient.
Results
Recordings from the device and a reference array in pigs were
identical in frequency (2.6 cycles per minute; p=0.91), and
activation patterns and velocities were consistent (8.9±0.2 vs
8.7±0.1 mm s−1; p=0.2). Device
and reference amplitudes were comparable (1.3±0.1 vs 1.4±0.1
mV; p=0.4), though the device signal to noise ratio (SNR)
was higher (17.5±0.6 vs 12.8±0.6 dB; P<0.0001). In
the human patient, corpus slow waves were recorded and mapped (frequency
2.7±0.03 cycles per minute, amplitude 0.8±0.4 mV, velocity
2.3±0.9 mm s−1).
Conclusion
In conclusion, the novel laparoscopic device achieves high-quality
serosal slow wave recordings. It can be used for laparoscopic diagnostic
studies to document slow wave patterns in patients with gastric motility
disorders.
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