Buqing Ni

Transvenous Phrenic Nerve Stimulation in Patients With Cheyne-Stokes Respiration and Congestive Heart Failure A Safety and Proof-of-Concept Study

BACKGROUND Cheyne-Stokes respiration (CSR), which often occurs in patients with congestive heart failure (CHF), may be a predictor for poor outcome. Phrenic nerve stimulation (PNS) may interrupt CSR in patients with CHF. We report the clinical use of transvenous PNS in patients with CHF and CSR. METHODS Nineteen patients with CHF and CSR were enrolled. A single stimulation lead was placed at the junction between the superior vena cava and brachiocephalic vein or in the left-side pericardiophrenic vein. PNS stimulation was performed using Eupnea System device (RespiCardia Inc). Respiratory properties were assessed before and during PNS. PNS was assessed at a maximum of 10 mA. RESULTS Successful stimulation capture was achieved in 16 patients. Failure to capture occurred in three patients because of dislocation of leads. No adverse events were seen under maximum normal stimulation parameters for an overnight study. When PNS was applied following a series of central sleep apneic events, a trend toward stabilization of breathing and heart rate as well as improvement in oxygen saturation was seen. Compared with pre-PNS, during PNS there was a significant decrease in apnea-hypopnea index (33.8 ± 9.3 vs 8.1 ± 2.3, P = .00), an increase in mean and minimal oxygen saturation as measured by pulse oximetry (89.7% ± 1.6% vs 94.3% ± 0.9% and 80.3% ± 3.7% vs 88.5% ± 3.3%, respectively, all P = .00) and end-tidal CO2 (38.0 ± 4.3 mm Hg vs 40.3 ± 3.1 mm Hg, P = .02), but no significant difference in sleep efficiency (74.6% ± 4.1% vs 73.7% ± 5.4%, P = .36). CONCLUSIONS The preliminary results showed that in a small group of patients with CHF and CSR, 1 night of unilateral transvenous PNS improved indices of CSR and was not associated with adverse events.

Prevention of postsurgical atrial tachycardia with a modified right atrial free wall incision

BACKGROUND Most postsurgical macroreentry atrial tachycardias (PS-MATs) are atriotomy related; however, underlying mechanisms and prevention remain undefined. OBJECTIVE The purpose of the present study was to investigate the electrophysiological and histologic bases of right atriotomy incision arrhythmogenicity and whether a modified atriotomy that extends the incisional line to the tricuspid annulus (TA) and inferior vena cava (IVC) prevents PS-MAT. METHODS Atrial arrhythmia induction and electrophysiological and histologic characteristics were studied 8 weeks after right atriotomy in 30 adult swine according to incision distance to TA or IVC (groups A, B, and C: broad, narrow, and closed corridors, respectively; group D, no-incision sham; n = 6 per group, except n = 12 for group B). RESULTS Sustained PS-MATs were induced and mapped in the broad- and narrow-corridor groups (A, 1 of 6 [16.7%] vs B, 5 of 12 [41.7%]) but not in the closed-corridor (C) or sham (D) groups (P = .087). With 20-ms pacing cycle-length decrements (from 350 to 270 ms), mean conduction time over 20 mm at the atriotomy-to-TA corridor was 29.2 ± 2.2, 31.0 ± 4.2, 26.0 ± 1.9, and 17.0 ± 1.4 ms for 5 and 10 mm (both group B), 15 mm (group A), and sham incision (P = .017), respectively. Conduction properties correlated with histologic findings: the wider the corridor, the healthier its tissue. In group C (modified atriotomy), both corridors were replaced by dense scar with complete conduction block. CONCLUSION Atriotomy corridor width determines conduction properties and contributes to arrhythmogenicity. A modified right atriotomy that extends to the TA and IVC prevents PS-MAT.

Prevalence and risk factors of sleep disordered breathing in patients with rheumatic valvular heart disease.

STUDY OBJECTIVES Sleep disordered breathing (SDB) is common in patients with chronic heart failure secondary to non-valvular heart disease; however, the prevalence and characteristics of SDB in patients with rheumatic valvular heart disease (RVHD) are unclear. This study was designed to determine the prevalence, characteristics, and risk factors for SDB in RVHD patients. METHODS A cross-sectional study was conducted in 260 RVHD patients. The following data were recorded: types of heart valve lesions, electrocardiographic, echocardiographic, arterial blood gas analysis findings, baseline medication, 6-minute walk test (6MWT) distance, and sleep parameters. RESULTS Compared to patients with single leftsided valve lesions, patients with left- and rightsided valve lesions had a higher prevalence of SDB (46.2% vs. 31.2%, p = 0.013); the increased prevalence of SDB only involved central sleep apnea (CSA) (31.1% vs. 14.1%, p = 0.001). Patients with obstructive sleep apnea (OSA) or CSA were older and had a shorter 6MWT distance, lower left ventricle ejection fraction and PaO₂, a longer lung-to-finger circulation time, and a higher prevalence of atrial fibrillation (AF) and hypertension (all p < 0.05) as compared with patients without SDB. Multinomial logistic regression analysis showed that PaO2 ≤ 85 mm Hg was the only risk factor for OSA. Male gender, AF, 6MWT distance ≤ 300 m, PaO₂ ≤ 85 mmHg, and PaCO₂ ≤ 40 mm Hg were risk factors for CSA. CONCLUSIONS Patients with RVHD had a high prevalence of SDB (predominantly CSA). RVHD patients with SDB, particularly those who had CSA, manifested more severe symptoms and greater impairment of cardiac function. Assessments of clinical manifestations of cardiac dysfunction may be important for predicting the risk factors for SDB.

Safety and feasibility of chronic transvenous phrenic nerve stimulation for treatment of central sleep apnea in heart failure patients.

Central sleep apnea (CSA) is common in patients with heart failure (HF) and is associated with poor quality of life and prognosis. Early acute studies using transvenous phrenic nerve stimulation (PNS) to treat CSA in HF have shown a significantly reduction of CSA and improvement of key polysomnographic parameters. In this study, we evaluated the safety of and efficiency chronic transvenous PNS with an implanted neurostimulator in HF patients with CSA.

Comparative Transcriptome Analysis Reveals Substantial Tissue Specificity in Human Aortic Valve.

RNA sequencing (RNA-seq) has revolutionary roles in transcriptome identification and quantification of different types of tissues and cells in many organisms. Although numerous RNA-seq data derived from many types of human tissues and cell lines, little is known on the transcriptome repertoire of human aortic valve. In this study, we sequenced the total RNA prepared from two calcified human aortic valves and reported the whole transcriptome of human aortic valve. Integrating RNA-seq data of 13 human tissues from Human Body Map 2 Project, we constructed a transcriptome repertoire of human tissues, including 19,505 protein-coding genes and 4,948 long intergenic noncoding RNAs (lincRNAs). Among them, 263 lincRNAs were identified as novel noncoding transcripts in our data. By comparing transcriptome data among different human tissues, we observed substantial tissue specificity of RNA transcripts, both protein-coding genes and lincRNAs, in human aortic valve. Further analysis revealed that aortic valve-specific lincRNAs were more likely to be recently derived from repetitive elements in the primate lineage, but were less likely to be conserved at the nucleotide level. Expression profiling analysis showed significant lower expression levels of aortic valve-specific protein-coding genes and lincRNA genes, when compared with genes that were universally expressed in various tissues. Isoform-level expression analysis also showed that a majority of mRNA genes had a major isoform expressed in the human aortic valve. To our knowledge, this is the first comparative transcriptome analysis between human aortic valve and other human tissues. Our results are helpful to understand the transcriptome diversity of human tissues and the underlying mechanisms that drive tissue specificity of protein-coding genes and lincRNAs in human aortic valve.

Identification of circular RNAs in human aortic valves

With the wide application of RNA-Seq technology, thousands of circular RNAs (circRNAs) have been identified in different type of tissues and cells in many organisms, but little is known on the human aortic valve expressed circRNAs. In this study, we identified all circRNAs in two calcified human aortic valves, and characterized the features of all circRNAs. A total of 5476 circRNAs were identified in human aortic valves, including 1412 (25.79%) aortic valve specific circRNAs. Next, we showed that most aortic valve specific circRNAs were derived from the exonic regions of their host genes, and majority of the host genes contained less than three circRNAs. To predict the potential function of aortic valve specific circRNAs, we performed the GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) enrichment analysis for the host genes, and identified both microRNA (miRNA) and RNA binding protein (RBP) binding sites inside aortic valve specific circRNAs. Results showed that these host genes were involved in some aortic valve related function pathways, such as ECM-receptor interaction pathway, ErbB signaling pathway, and vascular smooth muscle contraction pathway. We also found that most aortic valve specific circRNAs harbored abundant miRNA response elements (MREs), and some aortic valve specific circRNAs could bind to RBP of interest. Functional analysis suggested that these aortic valve specific circRNAs could act as post-transcriptional regulators.

Idiopathic isolated fibrotic atrial cardiomyopathy underlies unexplained scar-related atrial tachycardia in younger patients

Aims Unexplained scar-related atrial tachycardia (AT) has been frequently encountered in clinical practice. We hypothesized that idiopathic, isolated fibrotic atrial cardiomyopathy (ACM) underlies this rhythm disorder. This study was aimed to characterize the underlying substrate and to explore the aetiology of this unexplained scar-related AT. Methods and results Twenty-six (11 men, aged 46 ± 13 years) of 52 non-surgical scar-related AT patients identified by three-dimensional voltage mapping were enrolled in this prospective observational study. Multimodality image examinations (echocardiography, cardiac magnetic resonance, 99Tc single-photon emission computed tomography), ventricular voltage mapping, and intracardiac pressure curve recording ruled out ventricular involvement. Catheter ablation was acutely successful for all the patients, and pacemaker implantation was performed in seven patients who presented sinus node dysfunction or atrial standstill after termination of the AT. In three patients with multiple AT recurrences, the diseased areas of the right atrium were resected and dechannelled via mini-invasive surgical interventions. Histological examinations revealed profound fibrosis without amyloidosis or adipose deposition. Viral and familial investigations yielded negative results. Fibrosis progression over a median of 45 (5-109) months of follow-up manifested as atrial arrhythmia recurrence in seven patients and atrial lead non-capture due to newly developed atrial standstill in two patients. Two patients suffered four ischaemic stroke events before receiving anticoagulation treatment. Conclusion Isolated, fibrotic ACM may underlie the idiopathic scar-related ATs. This novel cardiomyopathy has unique clinical characteristics with high morbidity including stroke and warrants specific therapeutic strategies. Further investigations are required to determine the aetiology and mechanism.

Simultaneous resection of left atrial myxoma and esophageal carcinoma via right thoraco-abdominal approach

Concomitant occurrence of atrial myxoma and esophageal carcinoma is an extremely rare entity. Here we present two cases of synchronously suffered left atrial myxoma and esophageal carcinoma. Both patients underwent simultaneous resection of two tumors via the right thoraco-abdominal approach and recovered well.

Overnight fluid shifts in subjects with and without obstructive sleep apnea

OBJECTIVE To investigate the characteristics of baseline body fluid content and overnight fluid shifts between non-obstructive sleep apnea (non-OSA) and obstructive sleep apnea (OSA) subjects. METHODS A case-controlled study was performed between February 2013 and January 2014, with 36 (18 OSA and 18 non-OSA) outpatients enrolled in this study. Polysomnographic parameters and results of body fluid were compared between the two groups. RESULTS There were no differences in age, weight, and body mass index (BMI) between groups. Compared with the non-OSA group, OSA group had significantly higher neck circumference (NC) and fluid volume shift in the legs. OSA patients had higher left and right leg fluid indices than non-OSA subjects. There were significant correlations between apnoea-hypopnoea index and baseline fluid indices in both legs as well as the reduction in overnight change in both legs fluid volume. The increase in NC was also significantly correlated with the reduction in overnight change in both legs fluid volume, but not with the change in head and neck fluid volume. There were significant correlations between change in NC and increased fluid shifts in head and neck volume. CONCLUSIONS OSA patients had a higher baseline fluid content in both legs as compared with non-OSA subjects, which may be the basic factor with regards to fluid shifts in OSA patients. The increase in head and neck fluid shift volume did not directly correlate with the severity of OSA.

A Rare Life-threatening Kodamaea ohmeri Endocarditis Associated With Hemophagocytic Lymphohistiocytosis

We report the case of a 57-year-old man with a 3-month history of intermittent pyrexia. He received irregular antibacterial therapy and thrombolysis in a local hospital due to occlusion of the right distal popliteal artery. His medical history included multiple fractures, allergic purpura, and hypertension. His medications included prednisone (30 mg orally per day), metoprolol, and amlodipine. On physical examination, breath sounds were clear and a 3/6 pansystolic murmur was auscultated at the right sternal border. Swelling of the right leg and gangrene at the fifth toe were found. Abdominal palpation revealed mild splenomegaly. The following abnormal laboratory results were identified: white cell count, 3.20 10/L; platelet count, 30 10/L; hemoglobin, 8.80 g/dL; albumin, 2.99 g/dL; erythrocyte sedimentation rate, 42 mm/h; C-reactive protein, 13.30 mg/L; and ferritin, 674 mg/L. Three blood cultures were positive and a gram stain showed budding yeast cells. The isolate, after being subcultured on CHROMagar (Becton Dickinson, Paris, France), showed membranous colonies that changed color from pink to blue within 48 hours (Figure A). On corn meal agar (Becton Dickinson), pseudohyphae and blastoconidia were seen 24 hours later (Figure B). The yeasts were identified as Kodamaea ohmeri (K. ohmeri). Drug sensitivity testing showed that this strain was susceptible to voriconazole, fluconazole, itraconazole, and amphotericin B. Bone marrow aspiration, performed due to the cytopenia, showed phagocytosis of hematopoietic cells by activated macrophages (Figure C). Thoracoabdominal computed tomography revealed splenomegaly and mild bilateral pleural effusion. Transthoracic echocardiography showed a large vegetation (30 mm 12 mm) on the aortic valve with mild regurgitation and stenosis. On hospital day 5, the patient developed persistent pyrexia with a temperature of 39 8C despite antifungal therapy with intravenous voriconazole. Urgent surgery was performed and a large fragile and loose vegetation was found on the aortic valve that almost