Shortened chordae tendineae of the tricuspid valve with right ventricular dysfunction caused by acute myocarditis lead to cardiogenic shock during pericardial drainage: a case report.

A 63-year-old woman was admitted to the hospital with general malaise and pericardial and thoracoabdominal effusions of unknown cause. After pericardial drainage for drug-resistant right heart failure, she developed right ventricular (RV) dysfunction and cardiogenic shock caused by severe tricuspid regurgitation (TR). Findings during emergency surgery included tricuspid valve (TV) junction failure caused by shortening of the chordae tendineae of the TV, which is an organic abnormality. Additionally, myocardial biopsy results revealed myocarditis. Although acute myocarditis developed with RV dysfunction, pericardial effusion suppressed venous return, which temporarily improved her pathological condition. However, RV dysfunction and severe TR were thought to have manifested after the venous return suppression was alleviated by pericardial drainage. Because venous return changes significantly after pericardial drainage, it is necessary to examine the need for drainage and re-evaluate the post-operative RV system.

Predictors of increase in pacing threshold after transcatheter pacing system implantation due to micro-dislodgement.

BACKGROUND: Achieving a favorable pacing threshold with a Micra transcatheter pacing system (Micra-TPS) is needed to reduce battery depletion. In some cases, the threshold increases shortly after the device is implanted, and a higher pacing threshold may be required. This study aims to identify the causes and predictors of the increase in pacing threshold observed shortly after Micra-TPS implantation. METHODS: The study included 64 consecutive patients who underwent Micra-TPS implantation between 2017 and 2020. The patients were divided into two groups depending on their pacing threshold: the increased pacing threshold (IPT) group (threshold increased by ≥0.5 V/0.24 ms within 1 month of implantation) and the stable pacing threshold (SPT) group. RESULTS: Excluding four patients who could not be followed up, of the 60 remaining patients, nine (15%) were in the IPT group and 51 (85%) were in the SPT group. The IPT group had significantly lower implant impedance values and higher implant thresholds than the SPT group (582 ± 59 vs 755 ± 167 Ω [P < .001] and 1.29 ± 0.87 vs 0.71 ± 0.40 V/0.24 ms [P = .014]). Implant impedance and threshold may serve as predictors of a threshold increase after implantation (area under the curve: 0.737-0.943 and 0.586-0.926, respectively). CONCLUSIONS: An IPT was noted shortly after Micra-TPS implantation owing to micro-dislodgement because of insufficient anchoring of the device to the myocardium. Impedance >660 Ω and threshold <1.0 V/0.24 ms may predict an increase in pacing threshold.