Subcutaneous air entrapment after subcutaneous implantable cardioverter defibrillator implantation evaluated by computed tomography

BACKGROUND

Inappropriate shock (IAS) caused by subcutaneous air entrapment (AE) in an early period after subcutaneous implantable cardioverter defibrillator (S-ICD) implantation has been reported, however, no detailed data on air volume are available. We evaluated the subcutaneous air volume after implantation and its absorption rate one week after implantation.

METHODS

Patients who underwent S-ICD implantation in our hospital received chest CT scans immediately after implantation and followed up 1 week later. The total subcutaneous air volume, air around the generator, the distal electrode, and the proximal electrode within 3 cm were calculated using a three-dimensional workstation. Fat areas at the level of the lower edge of the generator were also analyzed.

RESULT

Fifteen patients received CT immediately after implantation. The mean age was 45.6 ± 17.9 (66.7% of men), and the mean body mass index was 24.3 ± 3.3. The three-incision technique was applied in seven patients and two-incision technique was in the latter eight patients. The mean total subcutaneous air volume was 18.54 ± 7.50 mL. Air volume around the generator, the distal electrode, and the proximal electrode were 11.05 ± 5.12, 0.72 ± 0.72, and 0.88 ± 0.87 mL, respectively. Twelve patients received a follow-up CT 1 week later. The mean total subcutaneous air was 0.25 ± 0.45 mL, showing a 98.7% absorption rate.

CONCLUSION

Although subcutaneous air was observed in all patients after S-ICD implantation, most of the air was absorbed within 1 week, suggesting a low occurrence of AE-related IAS after a week postoperation.

[Doxorubicin directly induced fibrotic change of cardiac fibroblasts]

Doxorubicin (DOX)-induced cardiomyopathy has a poor prognosis. No early detection or effective treatment methods are available in clinical. The mechanisms of cardiotoxicity were considered as oxidative stress and apoptosis in cardiomyocytes. However, the effect of DOX on cardiac fibroblasts remains to be developed. We investigated the direct effect of DOX on the function of human cardiac fibroblasts (HCFs) independently of cell death pathway. Animal study showed that lower dose of DOX (4 mg/kg/week for 3 weeks, i.p.) than a toxic cumulate dose, induced perivascular fibrosis without cell death in hear of mice. DOX increased the protein expression of α-SMA (a marker of trans-differentiation) in HCFs culture cells, indicating that DOX promoted the trans-differentiation of HCFs into myofibroblast. DOX also increased the mRNA and protein expression of matrix metalloproteinase (MMP)-1 in less than 0.1 μM which did not induce cell apoptosis of HCFs cells via PI3K/Akt pathway in HCFs. DOX increased Interleukin-6 (IL-6) via transforming growth factor (TGF)-β/Smad pathway. In addition, DOX induced the mitochondrial damage and increased the expression of Interleukin-1 (IL-1) via stress-activated protein kinases (SAPK)/ c-Jun NH-2termial kinase (JNK). A peroxisome proliferator-activated receptor gamma (PPARγ) agonist, pioglitazone hydrochloride attenuated the expression of fibrotic marker such as α-SMA and galectin-3 and collagen1 via SAPK/JNK signaling. Pioglitazone also suppressed DOX-induced early fibrotic response in vivo. In conclusion, these findings suggested that low dose DOX induced reactive fibrotic change of cardiac fibroblasts via cell death-independent pathway. There may be potentially new mechanisms of DOX induced cardiotoxicity in clinical usage.

A case report of pulmonary vein isolation with radiofrequency catheter using superior vena cava approach in patient with paroxysmal atrial fibrillation and inferior vena cava filter

Background

Transseptal puncture and pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF) are generally performed via the inferior vena cava (IVC). However, in cases where the IVC is inaccessible, a specific strategy may be needed.

Case summary

An 86-year-old woman with paroxysmal AF and an IVC filter in situ was referred to our hospital for ablation therapy. An IVC filter for pulmonary embolism and deep venous thrombosis had been implanted 15 years prior, therefore we selected a transoesophageal echocardiography (TOE)-guided transseptal puncture using a superior vena cava (SVC) approach. After the single transseptal puncture, we performed fast anatomical mapping, voltage mapping by multipolar mapping catheter, and then PVI by contact force-guided radiofrequency catheter using a steerable sheath. Following the ablation, bidirectional conduction block between the four pulmonary veins and the left atrium was confirmed by both radiofrequency and mapping catheter. No complications occurred and no recurrence of AF was documented in the 12 months after the procedure.

Discussion

When performing a transseptal puncture during AF ablation, an SVC approach, via access through the right internal jugular vein, enables the sheath to directly approach the left atrium without angulation and improves operability of the ablation catheter. Combining the use of general anaesthesia, TOE, a steerable sheath, and contact force-guided ablation may contribute to achieving minimally invasive PVI with a single transseptal puncture via an SVC approach.

Significance of Ventricular Arrhythmia Based on Stored Electrogram Analysis in a Pacemaker Population

The incidence of ventricular arrhythmia in patients with an implanted pacemaker is not yet known. The aim of this study was to analyze non-sustained ventricular tachycardia (NSVT) episodes based on stored electrograms (EGM) and determine the occurrence rate and risk factors for NSVT in a pacemaker population.This study included 302 consecutive patients with a dual-chamber pacemaker. A total of 1024 EGMs stored in pacemakers as ventricular high-rate episodes were analyzed. The definition of NSVT was ≥ 5 consecutive ventricular beats at ≥ 150 bpm lasting < 30 seconds.In baseline, most patients (94.8%) had ≥ 60% left ventricular ejection fraction. Of 1024 EGMs, 420 (41.0%) showed appropriate NSVT episodes, as well as premature atrial contractions, atrial tachyarrhythmia, or atrial fibrillation with a rapid ventricular response, whereas other EGMs did not show an actual ventricular arrhythmia. On EGM analysis, during a mean follow-up period of 46.1 months, NSVT occurred one or more times in 82 patients (33.1%). On multivariate analysis, ≥ 50% right ventricular pacing was an independent risk factor for NSVT (odds ratios, 4.519; P < 0.001), but NSVT was not associated with increased all-cause mortality.Moreover, in the pacemaker population, ≥ 50% right ventricular pacing is an independent risk factor for NSVT; however, NSVT was not associated with increased all-cause mortality because of the preserved left ventricular function.

P1050General anesthesia improved rate of first-pass pulmonary vein isolation by radiofrequency ablation in patients with atrial fibrillation

Background

Pulmonary vein isolation (PVI) with radiofrequency ablation (RFA) is one of the important procedures for atrial fibrillation (AF). Attaining the stability of RFA, respiratory management and pain control during the procedure are required.

Purpose

We compared the characteristic parameters and procedural outcomes between general anesthesia and moderate (conscious) sedation in patients with AF performed RFA.

Methods

We performed a retrospective, 2-center observational study to compare the general anesthesia with moderate sedation during RFA on AF from January 2018 until December 2018. In general anesthesia group, we administrated propofol and muscle relaxants under mechanical ventilation. In moderate sedation group, we administrated dexmedetomidine and/or propofol with analgesic drug. Procedural time of AF ablation, first-pass PVI (pulmonary vein isolation after completing the right or left circle) were assessed.

Results

A total of 98 patients with mean age 66 ± 11 years were enrolled (80 males, 81%). Of these, 19 patients were performed RFA under general anesthesia and 79 patients were performed under moderate sedation. Age, gender, BMI, medications before admission and CHADs2 score (general anesthesia:1.9 ± 1.2 vs moderate sedation:1.5 ± 1.1, p = 0.14), left atrium diameter (40.2 ± 6.2 vs 40.6 ± 6.8 mm, p = 0.81) and proportion of paroxysmal AF (47.4 vs 54.4%, p = 0.61) were similar between two groups. Our study found catheter RFA with general anesthesia to be associated with reduced procedural time (161 ± 29 vs 241 ± 58 minutes, p &lt; 0.01) and improved the rate of first-pass PVI (left pulmonary vein: 84.2 vs 59.5%, p = 0.06 and right pulmonary vein: 84.2 vs 58.2%, p =0.04).

Conclusions

RFA under general anesthesia improved first-pass PVI (quality of PVI) and shortened procedural time. General anesthesia may attribute to attaining the catheter and patient stability during RFA for PVI.

Reactive fibrosis precedes doxorubicin-induced heart failure through sterile inflammation

Aims

Doxorubicin (DOX)‐induced heart failure has a poor prognosis, and effective treatments have not been established. Because DOX shows cumulative cardiotoxicity, we hypothesized that minimal cardiac remodelling occurred at the initial stage in activating cardiac fibroblasts. Our aim was to investigate the initial pathophysiology of DOX‐exposed cardiac fibroblasts and propose prophylaxis.

Methods and results

An animal study was performed using a lower dose of DOX (4 mg/kg/week for 3 weeks, i.p.) than a toxic cumulative dose. Histological analysis was performed with terminal deoxynucleotidyl transferase‐mediated dUTP nick‐end labelling assay, picrosirius red staining, and immunohistochemical staining. The mechanism was analysed in vitro with a low dose of DOX, which did not induce cell apoptosis. Microarray analysis was performed. Differentially expressed genes were confirmed by enrichment analysis. Mitochondrial damage was assessed by mitochondrial membrane potential. The production of inflammatory cytokines and fibrosis markers was assessed by western blot, quantitative polymerase chain reaction, and ELISA. A phosphokinase antibody array was performed to detect related signalling pathways. Low‐dose DOX did not induced cell death, and fibrosis was localized to the perivascular area in mice. Microarray analysis suggested that DOX induced genes associated with the innate immune system and inflammatory reactions, resulting in cardiac remodelling. DOX induced mitochondrial damage and increased the expression of interleukin‐1. DOX also promoted the expression of fibrotic markers, such as alpha smooth muscle actin and galectin‐3. These responses were induced through stress‐activated protein kinase/c‐Jun NH2‐terminal kinase signalling. A peroxisome proliferator‐activated receptor (PPARγ) agonist attenuated the expression of fibrotic markers through suppressing stress‐activated protein kinase/c‐Jun NH2‐terminal kinase. Furthermore, this molecule also suppressed DOX‐induced early fibrotic responses in vivo.

Conclusions

Low‐dose DOX provoked reactive fibrosis through sterile inflammation evoked by the damaged mitochondria.

Doxorubicin induces trans-differentiation and MMP1 expression in cardiac fibroblasts via cell death-independent pathways

Although doxorubicin (DOX)-induced cardiomyopathy causes lethal heart failure (HF), no early detection or effective treatment methods are available. The principal mechanisms of cardiotoxicity are considered to involve oxidative stress and apoptosis of cardiomyocytes. However, the effect of DOX on cardiac fibroblasts at non-lethal concentrations remains unknown. The aim of this study was to investigate the direct effect of doxorubicin on the activation of cardiac fibroblasts independent of cell death pathways. We first found that DOX induced α-SMA expression (marker of trans-differentiation) at a low concentration range, which did not inhibit cell viability. DOX also increased MMP1, IL-6, TGF-β and collagen expression in human cardiac fibroblasts (HCFs). In addition, DOX promoted Akt and Smad phosphorylation. A Smad inhibitor prevented DOX-induced α-SMA and IL-6 protein expression. An PI3K inhibitor also prevented MMP1 mRNA expression in HCFs. These findings suggest that DOX directly induces fibrotic changes in HCFs via cell death-independent pathways. Furthermore, we confirmed that these responses are organ- and species-specific for HCFs based on experiments using different types of human and murine fibroblast cell lines. These results suggest potentially new mechanisms of DOX-induced cardiotoxicity from the viewpoint of fibrotic changes in cardiac fibroblasts.

Hydrostatic pressure suppresses fibrotic changes via Akt/GSK-3 signaling in human cardiac fibroblasts

Mechanical stresses play important roles in the process of constructing and modifying heart structure. It has been well established that stretch force acting on cardiac fibroblasts induces fibrosis. However, the effects of compressive force, that is, hydrostatic pressure (HP), have not been well elucidated. We thus evaluated the effects of HP using a pressure‐loading apparatus in human cardiac fibroblasts (HCFs) in vitro. In this study, high HP (200 mmHg) resulted in significant phosphorylation of Akt in HCFs. HP then greatly inhibited glycogen synthase kinase 3 (GSK‐3)α, which acts downstream of the PI3K/Akt pathway. Similarly, HP suppressed mRNA transcription of inflammatory cytokine‐6, collagen I and III, and matrix metalloproteinase 1, compared with an atmospheric pressure condition. Furthermore, HP inhibited collagen matrix production in a three‐dimensional HCF culture. Taken together, high HP suppressed the differentiation of fibroblasts into the myofibroblast phenotype. HP under certain conditions suppressed cardiac fibrosis via Akt/GSK‐3 signaling in HCFs. These results might help to elucidate the pathology of some types of heart disease.

Transient receptor potential cation 3 channel regulates melanoma proliferation and migration

Melanoma has an extremely poor prognosis due to its rapidly progressive and highly metastatic nature. Several therapeutic drugs have recently become available, but are effective only against melanoma with specific BRAF gene mutation. Thus, there is a need to identify other target molecules. We show here that Transient receptor potential, canonical 3 (TRPC3) is widely expressed in human melanoma. We found that pharmacological inhibition of TRPC3 with a pyrazole compound, Pyr3, decreased melanoma cell proliferation and migration. Similar inhibition was observed when the TRPC3 gene was silenced with short-hairpin RNA (shRNA). Pyr3 induced dephosphorylation of signal transducer and activator of transcription (STAT) 5 and Akt. Administration of Pyr3 (0.05 mg/kg) to mice implanted with human melanoma cells (C8161) significantly inhibited tumor growth. Our findings indicate that TRPC3 plays an important role in melanoma growth, and may be a novel target for treating melanoma in patients.

Basic studies of radiopaque resin monomer (III). Physical properties of trial composite resins

A series of studies has been conducted on the synthesis of radiopaque monomers and the development of a composite resin having these monomers. Using octachlorocyclotetraphosphazene, P4N4Cl8 (4PNC), three kinds of radiopaque cyclophosphazene monomers, 4PN(Br3Ph)1-3-(EMA)7-5, were synthesized by reacting 1-3 mols of tribromophenol (Br3Ph) and 7-5 mols of 2-hydroxyethyl methacrylate (HEMA). As the monomer for an organic composite filler, 70% (wt) synthesized monomer was used with silica (OX-50) treated with silane mixed at 30% and ground after heat-polymerization and then run through a 325-mesh sieve after polymerization. As a base monomer, 25% urethane monomer (U-2TH) was mixed in 25% synthesized monomer and photosensitizer was added. The composite resin was prepared by mixing 50% organic composite filler with 50% base monomer, and polymerized with a Dentacolor XS (Kulzer) visible light-curing apparatus by irradiation for 90 s on each side, 180 s in total. Mechanical properties did not vary with the increase in the number of tribromophenol replacements. Compressive yield strength was more than 120 MPa in all cases. Transverse strength was 60-75 MPa and hardness was HK 26-30. However, the aluminum equivalent increased with the increase in the number of tribromophenol replacements. In the case of 4PN-(Br3Ph)3, the value was 8.8 mm, whereas in the case of commercial composite resin, it was 0.4-10.4 mm.