Esophageal body adaptation to Nissen fundoplication: Increased esophagogastric outflow resistance yields delayed and sustained peristaltic contractions without increased amplitude.

BACKGROUND: Improvement in lower esophageal sphincter (LES) competency after laparoscopic Nissen fundoplication (LNF) is well established, yet esophageal body physiology data are limited. We aimed to describe the impact of LNF on whole esophagus physiology using standard and novel manometric characteristics.

METHODS: A cohort of patients with an intact fundoplication without herniation and no postoperative dysphagia were selected and underwent esophageal manometry at one-year after surgery. Pre- and post-operative manometry files were reanalyzed using standard and novel manometric characteristics and compared.

KEY RESULTS: A total of 95 patients were included in this study. At 16.1 (8.7) months LNF increased LES overall and abdominal length and resting pressure (p < 0.0001). Outflow resistance (IRP) increased [5.8 (3-11) to 11.1 (9-15), p < 0.0001] with a 95th percentile of 20 mmHg in this cohort of dysphagia-free patients. Distal contractile integral (DCI) also increased [1177.0 (667-2139) to 1321.1 (783-2895), p = 0.002], yet contractile amplitude was unchanged (p = 0.158). There were direct correlations between pre- and post-operative DCI [R: 0.727 (0.62-0.81), p < 0.0001] and postoperative DCI and postoperative IRP [R: 0.347 (0.16-0.51), p = 0.0006]. Contractile front velocity [3.5 (3-4) to 3.2 (3-4), p = 0.0013] was slower, while distal latency [6.7 (6-8) to 7.4 (7-9), p < 0.0001], the interval from swallow onset to proximal smooth muscle initiation [4.0 (4-5) to 4.4 (4-5), p = 0.0002], and the interval from swallow onset to point when the peristaltic wave meets the LES [9.4 (8-10) to 10.3 (9-12), p < 0.0001] were longer. Esophageal length [21.9 (19-24) to 23.2 (21-25), p < 0.0001] and transition zone (TZ) length [2.2 (1-3) to 2.5 (1-4), p = 0.004] were longer. Bolus clearance was inversely correlated with TZ length (p = 0.0002) and time from swallow onset to proximal smooth muscle initiation (p < 0.0001). Bolus clearance and UES characteristics were unchanged (p > 0.05).

CONCLUSIONS & INFERENCES: Increased outflow resistance after LNF required an increased DCI. However, this increased contractile vigor was achieved through sustained, not stronger, peristaltic contractions. Increased esophageal length was associated with increased TZ and delayed initiation of smooth muscle contractions.