Impact of maximum phonation time on postoperative dysphagia and prognosis after cardiac surgery

Objective

The incidence of postoperative complications, including dysphagia, increases as the population undergoing cardiovascular surgery ages. This study aimed to explore the potential of maximum phonation time (MPT) as a simple tool for predicting postextubation dysphagia (PED) and major adverse cardiac and cerebrovascular events (MACCEs).

Methods

This retrospective study included 442 patients who underwent elective cardiac surgery at a university hospital. MPT was measured before surgery, and patients were stratified into 2 groups based on normal and abnormal MPTs. Postoperative complications, including PED and MACCEs, were also investigated. Swallowing status was assessed using the Food Intake Level Scale.

Results

MPT predicted PED with prevalence of 11.0% and 18.0% in the normal and abnormal MPT groups, respectively (P = .01). During the follow-up period, MACCEs developed in 17.0% of patients. Frailty, European System for Cardiac Operative Risk Evaluation II score, PED, and MPT were markedly associated with MACCEs (adjusted hazard ratios: 2.25, 1.08, 1.96, and 0.96, respectively). Mediation analysis revealed that MPT positively influenced PED and MACCEs, whereas PED positively influenced MACCEs. The trend in restricted cubic spline analysis indicated that the hazard ratio for MACCEs increased sharply when MPT was <10 seconds.

Conclusions

These findings underscore the potential of MPT as a valuable tool in the preoperative assessment and management of patients undergoing cardiac surgery. By incorporating MPT into routine preoperative evaluations, clinicians can identify patients at a higher risk of PED and MACCEs, allowing for targeted interventions and closer postoperative monitoring. This may improve patient outcomes and reduce the health care costs associated with these complications.

Plasma cystine/methionine ratio is associated with left ventricular diastolic function in patients with heart disease

Elevated circulating homocysteine (Hcy) is a well-known risk factor for cardiovascular diseases (CVDs), including coronary artery disease (CAD) and heart failure (HF). It remains unclear how Hcy and its derivatives relate to left ventricular (LV) diastolic function. The aim of the present study was to investigate the relationship between plasma Hcy-related metabolites and diastolic dysfunction (DD) in patients with heart disease (HD). A total of 62 HD patients with preserved LV ejection fraction (LVEF ≥ 50%) were enrolled. Plasma Hcy and its derivatives were measured by liquid chromatography‒mass spectrometry (LC-MS/MS). Spearman's correlation test and multiple linear regression models were used to analyze the associations between metabolite levels and LV diastolic function. The cystine/methionine (CySS/Met) ratio was positively correlated with LV diastolic function, which was defined from the ratio of mitral inflow E and mitral e' annular velocities (E/e') (Spearman's r = 0.43, p < 0.001). When the subjects were categorized into two groups by E/e', the high-E/e' group had a significantly higher CySS/Met ratio than the low-E/e' group (p = 0.002). Multiple linear regression models revealed that the CySS/Met ratio was independently associated with E/e' after adjustment for age, sex, body mass index (BMI), diabetes mellitus, hypertension, chronic kidney disease (CKD),　hemoglobin, and lipid peroxide (LPO) {standardized β (95% CI); 0.14 (0.04-0.23); p = 0.005}. Hcy, CySS, and Met did not show a significant association with E/e' in the same models. A high plasma CySS/Met ratio reflected DD in patients with HD.

Postoperative dysphagia as a predictor of functional decline and prognosis after undergoing cardiovascular surgery

AIMS

Post-extubation dysphagia (PED), an often overlooked problem, is a common and serious complication associated with mortality and major morbidity after cardiovascular surgery. Dysphagia is considered an age-related disease, and evaluating its long-term effects is a pressing issue with rapidly progressing ageing worldwide. Therefore, we examined the effect of PED on functional status and long-term cardiovascular events in patients undergoing cardiovascular surgery.

METHODS AND RESULTS

This single-centre, retrospective cohort study included 712 patients who underwent elective cardiovascular surgery and met the inclusion criteria. Patients were divided into PED and non-PED groups based on their post-operative swallowing status. The swallowing status was assessed using the Food Intake Level Scale. Functional status was evaluated as hospital-associated disability (HAD), defined as a decrease in activities of daily living after hospital discharge compared with preoperative values. The patients were subsequently followed up to detect major adverse cardiac and cerebrovascular events (MACCEs). Post-extubation dysphagia was present in 23% of the 712 patients and was independently associated with HAD (adjusted odds ratio, 2.70). Over a 3.5-year median follow-up period, MACCE occurred in 14.1% of patients. Multivariate Cox proportional hazard analysis revealed HAD to be independently associated with an increased risk of MACCE (adjusted hazard ratio, 1.85), although PED was not significantly associated with MACCE.

CONCLUSION

Post-extubation dysphagia was an independent HAD predictor, with the odds of HAD occurrence being increased by 2.7-fold due to PED. Hospital-associated disability accompanied by PED is a powerful predictor of poor prognosis. Perioperative evaluation and management of the swallowing status, and appropriate therapeutic interventions, are warranted.

Fulminant myocarditis in a young woman with mixed connective tissue disease: a case report

Background

Although cardiac involvement is relatively common in mixed connective tissue disease (MCTD), few reports on MCTD-associated fulminant myocarditis are available.

Case summary

A 22-year-old woman diagnosed with MCTD was admitted to our institution for cold-like symptoms and chest pain. Echocardiography revealed that the left ventricular ejection fraction (LVEF) had rapidly decreased from 50 to 20%. Because endomyocardial biopsy revealed no significant lymphocytic infiltration, immunosuppressant drugs were not started initially; however, steroid pulse therapy (methylprednisolone, one1000 mg/day) was initiated due to prolonged symptoms and unimproved haemodynamics. Despite strong immunosuppressant therapy, the LVEF did not improve, and severe mitral regurgitation appeared. Three days after steroid pulse therapy initiation, she experienced a sudden cardiac arrest; thus, venoarterial extracorporeal membrane oxygenation (VA-ECMO) and intra-aortic balloon pumping (IABP) were initiated. Subsequent immunosuppressant therapy was continued with prednisolone (100 mg/day) and intravenous cyclophosphamide (1000 mg). Six days after steroid therapy initiation, the LVEF improved to 40% and then recovered to near-normal levels. After successful weaning off of VA-ECMO and IABP, she was discharged. Thereafter, a detailed histopathological examination revealed multi-focal signs of ischaemic micro-circulatory injury and diffuse HLA-DR in the vascular endothelium, suggesting an autoimmune inflammatory response.

Discussion

We report a rare case of fulminant myocarditis in a patient with MCTD who recovered with immunosuppressive treatment. Despite the absence of significant lymphocytic infiltration findings on histopathological examination, patients with MCTD may experience a dramatic clinical course. Although it is unclear whether myocarditis is triggered by viral infections, certain autoimmune mechanisms may lead to its development.

Inhibition of glutaminase 1-mediated glutaminolysis improves pathological cardiac remodeling

Alterations in cardiac metabolism are strongly associated with the pathogenesis of heart failure (HF). We recently reported that glutamine-dependent anaplerosis, termed glutaminolysis, was activated by H₂O₂ stimulation in rat cardiomyocytes, which seemed to be an adaptive response by which cardiomyocytes survive acute stress. However, the molecular mechanisms and fundamental roles of glutaminolysis in the pathophysiology of the failing heart are still unknown. Here, we treated wild-type mice (C57BL/6J) and rat neonatal cardiomyocytes (RNCMs) and fibroblasts (RNCFs) with angiotensin II (Ang II) to induce pathological cardiac remodeling. Glutaminase 1 (GLS1), a rate-limiting glutaminolysis enzyme, was significantly increased in Ang II-induced mouse hearts, RNCMs and RNCFs. Unexpectedly, a GLS1 inhibitor attenuated Ang II-induced left ventricular hypertrophy and fibrosis in the mice, and gene knockdown and pharmacological perturbation of GLS1 suppressed hypertrophy and the proliferation of RNCMs and RNCFs, respectively. Using mass spectrometry (MS)-based stable isotope tracing with ¹³C-labeled glutamine, we observed glutamine metabolic flux in Ang II-treated RNCMs and RNCFs. The incorporation of ¹³C atoms into tricarboxylic acid (TCA) cycle intermediates and their derivatives was markedly enhanced in both cell types, indicating the activation of glutaminolysis in hypertrophied heart. Notably, GLS1 inhibition reduced the production of glutamine-derived aspartate and citrate, which are required for the biosynthesis of nucleic acids and lipids, possibly contributing to the suppression of cardiac hypertrophy and fibrosis. The findings of the present study reveal that GLS1-mediated upregulation of glutaminolysis leads to maladaptive cardiac remodeling. Inhibition of this anaplerotic pathway could be a novel therapeutic approach for HF.

Impact of Frailty on Postoperative Dysphagia in Patients Undergoing Elective Cardiovascular Surgery

Background

Postextubation dysphagia (PED) is a serious postoperative complication following cardiovascular surgery that can lead to a worse prognosis. On the other hand, frailty is a prognostic factor in patients who undergo cardiac surgery.

Objectives

This study investigated the effect of frailty status on PED and impact of PED on postoperative complications.

Methods

This single-center retrospective cohort study included 644 consecutive patients who underwent elective cardiovascular surgery between May 1, 2014, and December 31, 2020; they were assigned to the PED or non-PED group based on postoperative swallowing status, and postoperative complications were investigated. Frailty status and physical functions, including walking speed, grip strength, Short Physical Performance Battery, and 6-minute walking distance, were preoperatively assessed; the frailty-status cutoff for predicting PED was determined from the receiver-operating characteristic curve.

Results

In this study cohort (mean age 67.7 years), the overall PED prevalence was 14.8%; preoperative frailty had a significantly higher prevalence in the PED group (50.0%) than in the non-PED group (20.3%; P < 0.001). PED correlated with a higher incidence of postoperative pneumonia and prolonged intensive care unit or hospital stay (P < 0.05 for all). After adjustment for confounders, multiple regression analysis revealed that preoperative frailty was independently associated with PED (P < 0.001).

Conclusions

PED occurred commonly after cardiovascular surgery and increased the risk of postoperative complications. Preoperative frailty was independently associated with PED. The 6-minute walking distance was the most powerful predictor of PED. Evaluation of preoperative frailty status is important for risk stratification and prevention of postoperative morbidity in patients undergoing surgery.

Preoperative frailty affects postoperative complications, exercise capacity, and home discharge rates after surgical and transcatheter aortic valve replacement

Assessment of frailty is important for risk stratification among the elderly with severe aortic stenosis (AS) when considering interventions such as surgical aortic valve replacement (SAVR) or transcatheter aortic valve replacement (TAVR). However, evidence of the impact of preoperative frailty on short-term postoperative outcomes or functional recovery is limited. This retrospective study included 234 consecutive patients with severe AS who underwent SAVR or TAVR at Kobe University Hospital between Dec 2013 and Dec 2019. Primary outcomes were postoperative complications, postoperative 6-min walking distance (6MWD), and home discharge rates. The mean age was 82 ± 6.6 years. There were 169 (SAVR: 80, TAVR: 89) and 65 (SAVR: 20, TAVR: 45) patients in the non-frail and frail groups, respectively (p = 0.02). The postoperative complication rates in the frail group were significantly higher than those in the non-frail group [30.8% (SAVR: 35.0%, TAVR: 28.9%) vs. 10.7% (SAVR: 15.0%, TAVR: 6.7%), p < 0.001]. The home discharge rate in the non-frail group was significantly higher than that in the frail group [85.2% (SAVR: 81.2%, TAVR: 88.8%) vs. 49.2% (SAVR: 55.0%, TAVR: 46.7%), p < 0.001]. The postoperative 6MWD in the non-frail group was significantly longer than that in the frail group [299.3 ± 87.8 m (SAVR: 321.9 ± 90.8 m, TAVR: 281.1 ± 81.3 m) vs. 141.9 ± 92.4 m (SAVR: 167.8 ± 92.5 m, TAVR: 131.6 ± 91.3 m), p < 0.001]. The TAVR group did not show a decrease in the 6MWD after intervention, regardless of frailty. We report for the first time that preoperative frailty was strongly associated with postoperative complications, 6MWD, and home discharge rates following both SAVR and TAVR. Preoperative frailty assessment may provide useful indications for planning better individualized therapeutic interventions and supporting comprehensive intensive care before and after interventions.

Critical role of glutamine metabolism in cardiomyocytes under oxidative stress

BACKGROUND

Metabolic remodeling in cardiomyocytes is deeply associated with the pathogenesis of heart failure (HF). Glutaminolysis is an anaplerotic pathway that incorporates α-ketoglutarate (αKG) derived from glutamine into the tricarboxylic acid (TCA) cycle. It is well known that cancer cells depend on glutamine for their increased energy demand and proliferation; however, the physiological roles of glutamine metabolism in failing hearts remain unclear.

OBJECTIVE

To investigate the regulatory mechanisms and biological effects of glutamine metabolism in oxidative stress-induced failing myocardium.

METHODS AND RESULTS

The intracellular levels of glutamine, glutamate, and αKG were significantly decreased by H₂O₂ stimulation in rat neonatal cardiomyocytes (RNCMs). To better understand the metabolic flux in failing myocardium, we performed a stable isotope tracing study and found that glutaminolysis was upregulated in RNCMs under oxidative stress. Consistent with this, the enzymatic activity of glutaminase (Gls), which converts glutamine to glutamate, was augmented in RNCMs treated with H₂O₂. These findings suggest that glutamine anaplerosis is enhanced in cardiomyocytes under oxidative stress to compensate for the reduction of αKG. Furthermore, the inhibition of Gls reduced cardiac cell viability, ATP production, and glutathione (GSH) synthesis in RNCMs with H₂O₂ stimulation. Finally, we evaluated the effects of αKG on failing myocardium and observed that dimethyl α-ketoglutarate (DMKG) suppressed oxidative stress-induced cell death likely due to the enhancement of intracellular ATP and GSH levels.

CONCLUSION

Our study demonstrates that under oxidative stress, glutaminolysis is upregulated to compensate for the loss of αKG and its replenishment into the TCA cycle, thereby exerting cardioprotective effects by maintaining ATP and GSH levels. Modulation of glutamine metabolism in failing hearts might provide a new therapeutic strategy for HF.

Relationship between oral health and physical frailty in patients with cardiovascular disease

BACKGROUND

Oral health is important for maintaining general health and is associated with components of physical frailty among the elderly. Oral health problems are common in hospitalized patients; however, no reports on oral health problems pertain to patients with cardiovascular diseases (CVD). The present study aimed to evaluate the association between oral health and physical frailty in these patients.

METHODS

In this retrospective cohort study, we included consecutive patients admitted for CVD to our hospital between May 2014 and December 2018. Physical frailty was assessed using the Short Physical Performance Battery (SPPB). Oral health characteristics, such as the number of remaining teeth, denture use, occlusal support, and periodontal status, were assessed.

RESULTS

In our cohort (n = 457), 111 (24.3%) patients had physical frailty. Univariate linear regression showed that the number of teeth present and the prevalence of occlusal support were significantly lower in patients with than without physical frailty. Pearson correlation indicated that the number of teeth significantly correlated with the nutritional status (r = 0.27) and SPPB score (r = 0.24), grip strength (r = 0.33), and 6-minute walking distance (r = 0.26). Multiple linear regression analysis showed that the number of teeth was independently associated with physical frailty after adjusting for confounders.

CONCLUSIONS

Oral health was closely associated with physical frailty, and nutritional status in patients with CVD; thus, it could be an important screening marker for early frailty symptoms and a predictor of future malnutrition risk.

In Vivo Imaging of Venous Thrombus and Pulmonary Embolism Using Novel Murine Venous Thromboembolism Model

•

We established a novel clinically relevant murine DVT model at femoral/saphenous vein induced by flow restriction and light illumination.

•

Our model newly succeeded in inducing DVT in a valve pocket and enabled spontaneous pulmonary embolism of fibrin-rich thrombus from lower extremity vein, reproducing the clinical VTE scenario.

•

This model is suitable for motion-free in vivo high-resolution imaging of fibrin-rich DVT development and organization using 2-photon microscopy, enabling the real-time imaging of migration of platelets and leukocytes into the erythrocyte-rich DVT.

This work established a new murine venous thromboembolism (VTE) model. This model has multiple novel features representing clinical VTE that include the following: 1) deep venous thrombosis (DVT) was formed and extended in the long axis of femoral/saphenous vein; 2) thrombus was formed in a venous valve pocket; 3) deligation of suture-induced spontaneous pulmonary emboli of fibrin-rich DVT; and 4) cardiac motion-free femoral/saphenous vein allowed high-resolution intravital microscopic imaging of fibrin-rich DVT. This new model requires only commercially available epifluorescence microscopy. Therefore, this model has significant potential for better understanding of VTE pathophysiology.

Effects of acute-phase multidisciplinary rehabilitation on unplanned readmissions after cardiac surgery

OBJECTIVES

The provision of inpatient programs that reduce the incidence of readmission after cardiac surgery remains challenging. Investigators have focused on multidisciplinary cardiac rehabilitation (CR) because it reduces the postoperative readmission rate; however, most previous studies used outpatient models (phase II CR). We retrospectively investigated the effect of comprehensive multidisciplinary interventions in the acute inpatient phase (phase I CR) on unplanned hospital readmission.

METHODS

In a retrospective cohort study, we compared consecutive patients after cardiac surgery. We divided them into the multidisciplinary CR (multi-CR) group or conventional exercise-based CR (conv-CR) group according to their postoperative intervention during phase I CR. Multi-CR included psychological and educational intervention and individualized counseling in addition to conv-CR. The primary outcome was unplanned readmission rates between the groups. A propensity score-matching analysis was performed to minimize selection biases and the differences in clinical characteristics.

RESULTS

In our cohort (n = 341), 56 (18.3%) patients had unplanned readmission during the follow-up period (median, 419 days). Compared with the conv-CR group, the multi-CR group had a significantly lower unplanned readmission rate (multivariable regression analysis; hazard ratio, 0.520; 95% confidence interval, 0.28-0.95; P = .024). A Kaplan-Meier analysis of our propensity score-matched cohort showed that, compared with the conv-CR group, the multi-CR group had a significantly lower incidence of readmission (stratified log-rank test, P = .041).

CONCLUSIONS

In phase I, compared to conv-CR alone, multi-CR reduced the incidence of unplanned readmission. Early multidisciplinary CR can reduce hospitalizations and improve long-term prognosis after cardiac surgery.

P5022Dual-energy CT was effective to evaluate of microvasculopathy in chronic thromboembolic pulmonary hypertension

Background

The existence of microvasculopathy in patients with chronic thromboembolic pulmonary hypertension (CTEPH) had been suggested. However, the impact of microvasculopathy for pathophysiology had been unknown. Recently dual-energy CT (DECT) can produce a sensitive iodine distribution map as blood perfusion in lung fields to quantify lung perfusion, also can suggest the existence of microvasculopathy according to poor subpleural perfusion which was published previously.

Methods

We retrospectively reviewed poor subpleural perfusion (defined as subpleural spaces either not or minimally perfused in all segments) and hemodynamics of 83 treatment-naïve CTEPH patients who underwent DECT from February 2014 to Jan 2019. Patients were divided according to poor subpleural perfusion: a microvasculopathy group (n=44) or a non-microvasculopathy group (n=39).

We assessed cardiopulmonary exercise test, right heart catheterization and DECT parameters as quantitative evaluation of pulmonary blood volume (PBV). PBV was calculated as the average of entire lung iodine density.

Results

PBV value in non-microvasculopathy group showed significant inverse correlation with pulmonary vascular resistance (PVR) (y = 14236 x-1.028 r=−0.530, p<0.01).

PBV, SvO2, and %DLCO/VA were significantly lower (22.0 vs. 26.4, p<0.01, 61.3 vs. 66.0, p<0.01, and 59.2 vs 75.9 p<0.01), and systolic pulmonary arterial pressure, PVR, VE/VCO2 slope, BNP were higher (69.3 vs 60.6 p=0.04, 834 vs 586 p<0.01, 45.5 vs. 37.8, p=0.02, and 440 vs 122 p=0.04) in microvasculopathy group, while the other parameters were similar between the two groups.

Multivariate analysis revealed that %DLCO/VA was the only predictor of microvasculopathy (OR,0.895 [95% CI, 0.835 - 0.960]; P<0.01).

Conclusion

Pulmonary blood flow of patients in non-micorvasculopathy group showed inverse correlation with PVR. DECT was effective to assess the microvasculopathy in CTEPH. In our experience, less than 60% of non-operable CTEPH patients have microvasculopathy.

Pulmonary Endarterectomy and Balloon Pulmonary Angioplasty for Chronic Thromboembolic Pulmonary Hypertension - Similar Effects on Health-Related Quality of Life

Background: While hemodynamics and exercise capacity in patients with chronic thromboembolic pulmonary hypertension (CTEPH) can be improved by invasive therapy such as pulmonary endarterectomy (PEA) and balloon pulmonary angioplasty (BPA), there has been little data on the health-related quality of life (HRQOL) in such patients. Methods and Results: This single-center and observational study compared the impact of invasive therapy on HRQOL. We utilized the Medical Outcome Study 36-Item Short Health Survey (SF-36) to measure HRQOL and compared HRQOL changes after PEA and BPA. A total of 48 patients were diagnosed with CTEPH. Of these, 39 patients completed questionnaires before and after invasive therapy. The PEA group (n=15) and the BPA group (n=24) had similar improvements in clinical parameters. With regard to HRQOL score, both groups had fairly low scores in physical functioning (PF), role physical (RP), general health (GH), social functioning (SF), role emotional (RE), and physical component summary (PCS) at baseline. PF, GH, vitality (VT), mental health (MH), and PCS had significant improvements in the PEA group while PCS and all subscales except for bodily pain (BP) had significant improvements in the BPA group. Furthermore, changes between baseline and follow-up were not significantly different between the 2 groups. Conclusions: BPA for patients who are ineligible for PEA can recover HRQOL to a similar level to that achieved by PEA.

Efficacy of preoperative amino acid supplements on postoperative physical function and complications in open heart surgery patients: A study protocol for a randomized controlled trial

BACKGROUND

Elderly patients undergoing cardiac surgery often show poor nutritional status, muscle wasting, and sarcopenia, which are reported to affect postoperative functional recovery and incidence of complications. Amino acids are essential in maintaining nutritional status, synthesizing muscle protein, and promoting beneficial energy balance of the heart muscle. β-Hydroxy β-methylbutyric acid (HMB) is a leucine metabolite known to increase muscle protein synthesis and inhibit protein catabolism; it has been used to more effectively support patients with muscle wasting due to wearing diseases. However, the efficacy of amino acid administration comprising HMB in patients undergoing open heart surgery remains unclear. This study aims to examine whether preoperative short-term aggressive amino acid administration helps support postoperative recovery of physical function and prevent complications.

METHODS

This is a single-center prospective randomized controlled trial (UMIN000030490). Patients aged ≥65 years who will be hospitalized for medical examination before cardiac surgery will be recruited. The participants will be randomly assigned to the experimental or control group. The experimental group will be administered with an amino acid supplement with HMB 1200mg, l-glutamine 7000mg, and l-arginine 7000mg once or twice per day depending on the degree of renal dysfunction, for 14-28 days preoperatively. The control group will not receive any nutritional intervention. The main outcome will be a change in the 6-min walking test distance pre- and postoperatively as a sign of functional recovery. Secondary outcomes such as the incidence of complications; physical, nutritional, and psychological states; mortality; and length of hospital stay will also be evaluated.

CONCLUSION

This clinical study will determine the effects of preoperative short-term oral amino acid supplementation with HMB, l-glutamine, and l-arginine on postoperative physical function in elderly patients undergoing cardiac surgery.

Effects of postoperative dietary intake on functional recovery of patients undergoing cardiac surgery

BACKGROUND AND AIM

Among elderly patients undergoing cardiac surgery, malnutrition is very common and related to muscle wasting known as sarcopenia. Cardiac surgery causes a further decline of nutritional status due to reduced dietary intake (DI); however, the impact of postoperative DI on functional recovery is unclear.

METHODS AND RESULTS

We enrolled 250 consecutive patients undergoing cardiac surgery. Daily DI was measured between postoperative days 3 and 7. Patients were categorized as having sufficient or insufficient DI based on whether their DI met or was less than estimated total energy requirements. Functional capacity was measured using the 6-minute walking distance (6MWD) preoperatively and at discharge. Mean postoperative DI was 22.4 ± 3.0 kcal/kg/day, and postoperative DI was insufficient in 92 patients (36.8%). The prevalence of sarcopenia was not different by postoperative DI. Although there was no significant difference in preoperative 6MWD results (P = 0.65), the sufficient DI group had longer 6MWD at discharge than the insufficient DI group (P = 0.04). In multivariate regression analysis, preoperative poor nutritional status (β = -0.29), duration of surgery (β = -0.18), and postoperative DI (β = 0.40) remained statistically significant predictors for improvement of 6MWD (P < 0.0001, adjusted R² = 0.41).

CONCLUSIONS

Postoperative DI was independently associated with functional recovery, but preoperative sarcopenia was not. Regardless of preoperative nutritional status or the presence of sarcopenia, aggressive nutritional intervention in the early stage after surgery helps support functional recovery.

Sequential Hybrid Therapy With Pulmonary Endarterectomy and Additional Balloon Pulmonary Angioplasty for Chronic Thromboembolic Pulmonary Hypertension

Background

Residual symptoms after pulmonary endarterectomy (PEA) remain as the clinical issues to be solved. Additional balloon pulmonary angioplasty (BPA) after PEA showed its efficacy with symptoms in a case series, although long‐term spontaneous recovery of exercise ability after PEA was also reported. However, no studies have validated the clinical efficacy of additional BPA by directly comparing PEA with and without BPA. The aim of this study was to retrospectively evaluate the efficacy of additional BPA as a sequential hybrid therapy for chronic thromboembolic pulmonary hypertension after PEA.

Methods and Results

Among 44 patients with chronic thromboembolic pulmonary hypertension, 20 patients had residual symptoms after PEA. Of those, 10 patients underwent additional BPA (hybrid group) and were compared with the other 10 patients, who were followed up without BPA (PEA group). The period from PEA to additional BPA was 7.3±2.3 months. In hybrid group, mean pulmonary arterial pressure was significantly improved by PEA (40.6±1.8 to 26.9±3.1 mm Hg, P=0.001) and improved further (to 16.7±1.8 mm Hg, P=0.002) with additional BPA, which resulted in remarkable improvement in World Health Organization (WHO) functional class (pre‐ to post‐BPA: class I/II/III/IV, 0/5/4/1 to 7/3/0/0; P<0.001). Compared with the PEA group at follow‐up, the hybrid group achieved better mean pulmonary arterial pressure (18.7±1.7 versus 30.2±3.2 mm Hg, P=0.008), WHO functional class (class I/II/III/IV, 7/3/0/0 versus 0/8/2/0; P=0.001), and 6‐minute walking distance (429±38 versus 319±22 m, P=0.028).

Conclusions

A sequential hybrid strategy improved residual symptoms and exercise capacity compared with single‐PEA therapy.

Preoperative exercise capacity is associated with the prevalence of postoperative delirium in elective cardiac surgery

BACKGROUND

Postoperative delirium (POD) is a critical complication that is closely associated with mortality and major morbidity in elective cardiac surgery. The identification of patients at risk for POD is crucial but has not been fully explored.

AIMS

The aim of this study was to determine the predictive value of the assessment of preoperative exercise capacity for POD.

METHODS

We enrolled 313 consecutive patients (mean age, 68.6 ± 14.8 years) undergoing elective cardiac surgery. We measured physical functions such as the 6-minute walking distance (6MWD) and Timed Up-and-Go test (TUG) before surgery. The assessment of delirium was conducted every 8 h from the day of surgery to 5 days after surgery using the Intensive Care Delirium Screening Checklist.

RESULTS

POD occurred in 46 patients (14.6%). Age, 6MWD, TUG, serum hemoglobin, estimated glomerular filtration rate, and length of intensive care unit stay were significantly different based on the presence or absence of POD (p < 0.05 for each). After multivariate analysis, 6MWD remained a statistically significant indicator for developing POD (OR 0.98; p = 0.02). The cut-off value of 6MWD for predicting POD was 345 m (AUC = 0.75; p = 0.001).

CONCLUSIONS

Poor exercise capacity was found to be an independent predictor of POD following elective cardiac surgery. This finding suggests the importance of preoperative functional evaluation in the prevention and management of POD in cardiac surgery patients.

Impact of delirium on postoperative frailty and long term cardiovascular events after cardiac surgery

BACKGROUND

Postoperative delirium (POD) is a common and critical complication after cardiac surgery. However, the relationship between POD and postoperative physical frailty and the effect of both on long-term clinical outcomes have not been fully explored.

OBJECTIVE

We aimed to examine the associations among POD, postoperative frailty, and major adverse cardiac events (MACE).

DESIGN

This was a prospective cohort study.

METHODS

We studied 329 consecutive patients undergoing elective cardiac surgery. The intensive care delirium screening checklist was used to assess POD. Postoperative frailty was defined by handgrip strength and walking speed. Patients were subsequently followed-up to detect MACE.

RESULTS

POD was present in 13.2%, while the incidence of postoperative frailty was 27.0%. POD was independently associated with development of postoperative frailty (adjusted odds ratio = 2.98). During follow-up, MACE occurred in 14.1% of all participants. On multivariate Cox proportional hazard analysis, POD (adjusted hazard ratio (HR) = 3.36), postoperative frailty (HR = 2.21), postoperative complications (HR = 1.54), and left ventricular ejection fraction (HR = 0.95) were independently associated with increased risk of MACE.

LIMITATIONS

It is a single-center study with a risk of bias. We did not investigate follow up cognitive function.

CONCLUSIONS

POD was a predictor of postoperative frailty after cardiac surgery. Both postoperative frailty and POD were associated with the incidence of MACE, while POD was the stronger predictor of MACE. Thus, POD and frailty play critical roles in the risk stratification of patients undergoing cardiac surgery.

Poor preoperative nutritional status is an important predictor of the retardation of rehabilitation after cardiac surgery in elderly cardiac patients

BACKGROUND

Preoperative nutritional status and physical function are important predictors of mortality and morbidity after cardiac surgery. However, the influence of nutritional status before cardiac surgery on physical function and the progress of postoperative rehabilitation requires clarification.

AIMS

To determine the effect of preoperative nutritional status on preoperative physical function and progress of rehabilitation after elective cardiac surgery.

METHODS

We enrolled 131 elderly patients with mean age of 73.7 ± 5.8 years undergoing cardiac surgery. We divided them into two groups by nutritional status as measured by the Geriatric Nutritional Risk Index (GNRI): high GNRI group (GNRI ≥ 92, n = 106) and low GNRI group (GNRI < 92, n = 25). Physical function was estimated by handgrip strength, knee extensor muscle strength (KEMS), the Short Physical Performance Battery (SPPB), and 6-minute walk test (6MWT). Progress of postoperative rehabilitation was evaluated by the number of days to independent walking after surgery, length of stay in the ICU, and length of hospital stay.

RESULTS

After adjusting for potential confounding factors, preoperative handgrip strength (P = 0.034), KEMS (P = 0.009), SPPB (P < 0.0001), and 6MWT (P = 0.012) were all significantly better in the high GNRI group. Multiple regression analysis revealed that a low GNRI was an independent predictor of the retardation of postoperative rehabilitation.

CONCLUSIONS

Preoperative nutritional status as assessed by the GNRI could reflect perioperative physical function. Preoperative poor nutritional status may be an independent predictor of the retardation of postoperative rehabilitation in patients undergoing elective cardiac surgery.

Anti-mitochondrial M2 Antibodies Enhance the Risk of Supraventricular Arrhythmias in Patients with Elevated Hepatobiliary Enzyme Levels

Objective Supraventricular arrhythmias are commonly detected in patients with anti-mitochondrial antibody M2 (AMA-M2)-associated myopathy. However, the prevalence of supraventricular arrhythmias in unselected AMA-M2-positive patients and the impact of AMA-M2 on supraventricular arrhythmias have yet to be fully investigated. Methods We analyzed 384 patients (116 men; age, 60 [48-69] years), who underwent AMA-M2 testing following the detection of elevated hepatobiliary enzymes. Supraventricular arrhythmias involving atrial fibrillation, atrial flutter, atrial tachycardia, sick sinus syndrome, and atrial standstill were confirmed by a 12-lead electrocardiogram, 24-hour ambulatory monitoring, and physician-assigned diagnoses within the three years before and two years after the AMA-M2 test. Results Seventy-seven (20%) patients were positive for AMA-M2. The prevalence of supraventricular arrhythmias among AMA-M2-positive patients was higher than that among AMA-M2-negative patients (14% vs. 6%, p=0.008). A univariate analysis showed that supraventricular arrhythmias were associated with AMA-M2 positivity, aging, congestive heart failure, and the CHADS₂ score. The multivariate analysis determined that AMA-M2 positivity was an independent risk factor for supraventricular arrhythmias (odds ratio 3.52, p=0.011). Among the AMA-M2-positive patients, the AMA-M2 titer did not differ to a statistically significant extent, regardless of the presence or absence of supraventricular arrhythmias. Multiple supraventricular arrhythmias with extremely low atrial deflections was a characteristic finding in AMA-M2-positive patients with supraventricular arrhythmias. Conclusion AMA-M2 enhances the risk of supraventricular arrhythmias, indicating the possible involvement of the atrial myocardium and the formation of an arrhythmogenic substrate. The results highlight the need for clinical attention to supraventricular arrhythmias in AMA-M2-positive patients.

β-Hydroxybutyrate elevation as a compensatory response against oxidative stress in cardiomyocytes

Recent studies have shown that the ketone body β-hydroxybutyrate (βOHB) acts not only as a carrier of energy but also as a signaling molecule that has a role in diverse cellular functions. Circulating levels of ketone bodies have been previously reported to be increased in patients with congestive heart failure (HF). In this study, we investigated regulatory mechanism and pathophysiological role of βOHB in HF. First, we revealed that βOHB level was elevated in failing hearts, but not in blood, using pressure-overloaded mice. We also measured cellular βOHB levels in both cardiomyocytes and non-cardiomyocytes stimulated with or without H2O2 and revealed that increased myocardial βOHB was derived from cardiomyocytes but not non-cardiomyocytes under pathological states. Next, we sought to elucidate the mechanisms of myocardial βOHB elevation and its implication under pathological states. The gene and protein expression levels of CoA transferase (SCOT), a key enzyme involved in ketone body oxidation, was decreased in failing hearts. In cardiomyocytes, H2O2 stimulation caused βOHB accumulation concomitantly with SCOT downregulation, implying that the accumulation of myocardial βOHB occurs because of the decline in its utilization. Finally, we checked the effects of βOHB on cardiomyocytes under oxidative stress. We found that βOHB induced FOXO3a, an oxidative stress resistance gene, and its target enzyme, SOD2 and catalase. Consequently, βOHB attenuated reactive oxygen species production and alleviated apoptosis induced by oxidative stress. It has been reported that hyperadrenergic state in HF boost lipolysis and result in elevation of circulating free fatty acids, which can lead hepatic ketogenesis for energy metabolism alteration. The present findings suggest that the accumulation of βOHB also occurs as a compensatory response against oxidative stress in failing hearts.

Serum phosphate is an independent predictor of the total aortic calcification volume in non-hemodialysis patients undergoing cardiovascular surgery

BACKGROUND

A high serum phosphate level is a well-known risk factor for vascular calcification (VC) in patients on hemodialysis (HD). However, the association between the serum phosphate level and VC in non-HD patients is unclear. Our aim was to assess the impact of serum phosphate level on aortic calcification (AC) volume in non-HD patients undergoing cardiovascular surgery.

METHODS

A total of 117 patients who underwent thoracoabdominal computed tomography as a preoperative general evaluation before cardiovascular surgery were enrolled. The total AC volume was quantified using the volume-rendering method by extracting the area ≥130HU within the entire aorta. The total AC volume index (AC-VI) was estimated as the total AC volume divided by the body surface area.

RESULTS

In the 117 patients (64.7±13.1 years, 39% women), the median total AC-VI was 1.23mL/m(2). The mean estimated glomerular filtration rate (eGFR), adjusted serum calcium levels, and serum phosphate levels were 63.8±19.9mL/min/1.73m(2), 9.1±0.4mg/dL, and 3.6±0.6mg/dL, respectively. When the patients were classified into four quartiles based on their total AC-VI value, the serum phosphate level showed a positive correlation with a probability of being in the highest AC-VI quartile (R(2)=0.0146, p=0.0383) whereas the adjusted serum calcium level did not show a significant correlation (R(2)=0.0040, p=0.2615). A similar relationship between the serum phosphate level, adjusted serum calcium level, and AC-VI was confirmed when the total AC-VI was divided into the thoracic AC-VI and abdominal AC-VI. Multivariate analysis indicated that the serum phosphate level was an independent positive predictor of higher total AC-VI quartiles (β=0.8013, p=0.0160).

CONCLUSIONS

An increase in serum phosphate level was associated with an increased AC burden in non-HD patients undergoing cardiovascular surgery.

Involvement of Rho-associated protein kinase (ROCK) and bone morphogenetic protein-binding endothelial cell precursor-derived regulator (BMPER) in high glucose-increased alkaline phosphatase expression and activity in human coronary artery smooth muscle cells

Background

Vascular calcification is an independent risk factor for cardiovascular disease. Diabetes mellitus increases the incidence of vascular calcification; however, detailed molecular mechanisms of vascular calcification in diabetes mellitus remain unknown. We recently reported that bone morphogenetic protein-binding endothelial cell precursor-derived regulator (BMPER) regulates osteoblast-like trans-differentiation of human coronary artery smooth muscle cells (HCASMCs).

Methods

We investigated the effect of a hydroxymethylglutaryl-coenzyme A reductase inhibitor (statin), commonly used in patients with atherosclerotic diseases and diabetes mellitus, on alkaline phosphatase (ALP) mRNA expression in aortas of streptozotocin-induced diabetic mice. We also investigated the effects of the statin, Rho-associated protein kinase (ROCK) inhibitors and BMPER knockdown on ALP mRNA expression and activity in HCASMCs cultured in high glucose-containing media.

Results

Alkaline phosphatase mRNA expression was increased in aortas of streptozotocin-induced diabetic mice, and the increase was inhibited by rosuvastatin. ALP mRNA expression and activity were increased in HCASMCs cultured in high glucose-containing media, and the increases were suppressed by rosuvastatin. This suppression was reversed by the addition of mevalonate or geranylgeranyl pyrophosphate, but not farnesyl pyrophosphate. High glucose-increased ALP mRNA expression and activity were suppressed by ROCK inhibitors. Moreover, BMPER mRNA expression was increased in diabetic mouse aortas and in HCASMCs cultured in high glucose-containing media, but was not inhibited by rosuvastatin or ROCK inhibitors. Knockdown of BMPER suppressed high glucose-increased ALP activity, but not ROCK activity in HCASMCs.

Conclusions

There are at least two independent pathways in high glucose-induced ALP activation in HCASMCs: the Rho–ROCK signaling pathway and the BMPER-dependent pathway.

Family with sequence similarity 5, member C (FAM5C) increases leukocyte adhesion molecules in vascular endothelial cells: implication in vascular inflammation

Identification of the regulators of vascular inflammation is important if we are to understand the molecular mechanisms leading to atherosclerosis and consequent ischemic heart disease, including acute myocardial infarction. Gene polymorphisms in family with sequence similarity 5, member C (FAM5C) are associated with an increased risk of acute myocardial infarction, but little is known about the function of this gene product in blood vessels. Here, we report that the regulation of the expression and function of FAM5C in endothelial cells. We show here that FAM5C is expressed in endothelial cells in vitro and in vivo. Immunofluorescence microcopy showed localization of FAM5C in the Golgi in cultured human endothelial cells. Immunohistochemistry on serial sections of human coronary artery showed that FAM5C-positive endothelium expressed intercellular adhesion molecule-1 (ICAM-1) or vascular cell adhesion molecule-1 (VCAM-1). In cultured human endothelial cells, the overexpression of FAM5C increased the reactive oxygen species (ROS) production, nuclear factor-κB (NF-κB) activity and the expression of ICAM-1, VCAM-1 and E-selectin mRNAs, resulting in enhanced monocyte adhesion. FAM5C was upregulated in response to inflammatory stimuli, such as TNF-α, in an NF-κB- and JNK-dependent manner. Knockdown of FAM5C by small interfering RNA inhibited the increase in the TNF-α-induced production of ROS, NF-κB activity and expression of these leukocyte adhesion molecule mRNAs, resulting in reduced monocyte adhesion. These results suggest that in endothelial cells, when FAM5C is upregulated in response to inflammatory stimuli, it increases the expression of leukocyte adhesion molecules by increasing ROS production and NF-κB activity.

Endothelial lipase modulates pressure overload-induced heart failure through alternative pathway for fatty acid uptake

Lipoprotein lipase has been considered as the only enzyme capable of generating lipid-derived fatty acids for cardiac energy. Endothelial lipase is another member of the triglyceride lipase family and hydrolyzes high-density lipoproteins. Although endothelial lipase is expressed in the heart, its function remains unclear. We assessed the role of endothelial lipase in the genesis of heart failure. Pressure overload-induced cardiac hypertrophy was generated in endothelial lipase(-/-) and wild-type mice by ascending aortic banding. Endothelial lipase expression in cardiac tissues was markedly elevated in the early phase of cardiac hypertrophy in wild-type mice, whereas lipoprotein lipase expression was significantly reduced. Endothelial lipase(-/-) mice showed more severe systolic dysfunction with left-ventricular dilatation compared with wild-type mice in response to pressure overload. The expression of mitochondrial fatty acid oxidation-related genes, such as carnitine palmitoyltransferase-1 and medium-chain acyl coenzyme A dehydrogenase, was significantly lower in the heart of endothelial lipase(-/-) mice than in wild-type mice. Also, endothelial lipase(-/-) mice had lower myocardial adenosine triphosphate levels than wild-type mice after aortic banding. In cultured cardiomyocytes, endothelial lipase was upregulated by inflammatory stimuli, whereas lipoprotein lipase was downregulated. Endothelial lipase-overexpression in cardiomyocytes resulted in an upregulation of fatty acid oxidation-related enzymes and intracellular adenosine triphosphate accumulation in the presence of high-density lipoprotein. Endothelial lipase may act as an alternative candidate to provide fatty acids to the heart and regulate cardiac function. This effect seemed relevant particularly in the diseased heart, where lipoprotein lipase action is downregulated.

Osteoblast-like differentiation of cultured human coronary artery smooth muscle cells by bone morphogenetic protein endothelial cell precursor-derived regulator (BMPER)

Differentiation of vascular smooth muscle cells (SMCs) into osteoblast-like cells is considered to be a mechanism of vascular calcification. However, regulators of osteoblast-like differentiation of vascular SMCs are not fully elucidated. Here, we investigated the expression of bone morphogenetic protein (BMP)-binding endothelial cell precursor-derived regulator (BMPER), a vertebrate homologue of Drosophila crossveinless-2, in vascular SMCs and the role and mode of action of BMPER in osteoblast-like differentiation of human coronary artery SMCs (HCASMCs). BMPER was expressed in cultured human vascular SMCs, including HCASMCs. Silencing of endogenous BMPER expression by an RNA interference technique inhibited osteoblast-like differentiation of HCASMCs, as evaluated by up-regulation of osteoblast markers such as alkaline phosphatase (ALP) and runt-related transcription factor 2 (Runx2), by down-regulation of a SMC marker α-smooth muscle actin (αSMA), and by mineralization. Treatment with recombinant BMPER enhanced, whereas BMP-2 reduced osteoblast-like differentiation. BMPER antagonized BMP-2-induced phosphorylation of Smad 1/5/8, suggesting that the effect of BMPER was mediated by antagonizing the action of BMP. BMPER increased IκBα phosphorylation and NF-κB activity and specific NF-κB decoy oligonucleotides deteriorated osteoblast-like differentiation of HCASMCs by BMPER. In human coronary artery with atherosclerotic plaque containing calcification, the BMPER-positive signals were observed in the neointimal and medial SMCs in the vicinity of the plaque. These findings indicate that BMPER is a novel regulator of the osteoblast-like differentiation of HCASMCs.

Necl-5/poliovirus receptor interacts with VEGFR2 and regulates VEGF-induced angiogenesis

RATIONALE

Vascular endothelial growth factor (VEGF), a major proangiogenic agent, exerts its proangiogenic action by binding to VEGF receptor 2 (VEGFR2), the activity of which is regulated by direct interactions with other cell surface proteins, including integrin α(V)β(3). However, how the interaction between VEGFR2 and integrin α(V)β(3) is regulated is not clear.

OBJECTIVE

To investigate whether Necl-5/poliovirus receptor, an immunoglobulin-like molecule that is known to bind integrin α(V)β(3), regulates the interaction between VEGFR2 and integrin α(V)β(3), and to clarify the role of Necl-5 in the VEGF-induced angiogenesis.

METHODS AND RESULTS

Necl-5-knockout mice displayed no obvious defect in vascular development; however, recovery of blood flow after hindlimb ischemia and the VEGF-induced neovascularization in implanted Matrigel plugs were impaired in Necl-5-knockout mice. To clarify the mechanism of the regulation of angiogenesis by Necl-5, we investigated the roles of Necl-5 in the VEGF-induced angiogenic responses in vitro. Knockdown of Necl-5 by siRNAs in human umbilical vein endothelial cells (HUVECs) inhibited the VEGF-induced capillary-like network formation on Matrigel, migration, and proliferation, and conversely, enhanced apoptosis. Coimmunoprecipitation assays showed the interaction of Necl-5 with VEGFR2, and knockdown of Necl-5 prevented the VEGF-induced interaction of integrin α(V)β(3) with VEGFR2. Knockdown of Necl-5 suppressed the VEGFR2-mediated activation of downstream proangiogenic and survival signals, including Rap1, Akt, and endothelial nitric oxide synthase.

CONCLUSIONS

These results demonstrate the critical role of Necl-5 in angiogenesis and suggest that Necl-5 may regulate the VEGF-induced angiogenesis by controlling the interaction of VEGFR2 with integrin α(v)β(3), and the VEGFR2-mediated Rap1-Akt signaling pathway.

Role of Afadin in Vascular Endothelial Growth Factor– and Sphingosine 1-Phosphate–Induced Angiogenesis

Rationale : Angiogenesis contributes to physiological and pathological conditions, including atherosclerosis. The Rap1 small G protein regulates vascular integrity and angiogenesis. However, little is known about the effectors of Rap1 involved in angiogenesis. It is not known whether afadin, an adherens junction protein that connects immunoglobulin-like adhesion molecule nectins to the actin cytoskeleton and binds activated Rap1, plays a role in angiogenesis.

Objective : We investigated the role of endothelial afadin in angiogenesis and attempted to clarify the underlying molecular mechanism.

Methods and Results : Treatment of human umbilical vein endothelial cells (HUVECs) with vascular endothelial growth factor (VEGF) and sphingosine 1-phosphate (S1P) induced the activation of Rap1. Activated Rap1 regulated intracellular localization of afadin. Knockdown of Rap1 or afadin by small interfering RNA inhibited the VEGF- and S1P-induced capillary-like network formation, migration, and proliferation, and increased the serum deprivation-induced apoptosis of HUVECs. Knockdown of Rap1 or afadin decreased the accumulation of adherens and tight junction proteins to the cell–cell contact sites. Rap1 regulated the interaction between afadin and phosphatidylinositol 3-kinase (PI3K), recruitment of the afadin–PI3K complex to the leading edge, and the activation of Akt, indicating the involvement of Rap1 and afadin in the PI3K–Akt signaling pathway. Binding of afadin to Rap1 regulated the activity of Rap1 in a positive-feedback manner. In vivo, conditional deletion of afadin in mouse vascular endothelium using a Cre-loxP system impaired the VEGF- and S1P-induced angiogenesis.

Conclusions : These results demonstrate a novel molecular mechanism by which Rap1 and afadin regulate the VEGF- and S1P-induced angiogenesis.

Deficiency of nectin-2 leads to cardiac fibrosis and dysfunction under chronic pressure overload

The intercalated disc, a cell-cell contact site between neighboring cardiac myocytes, plays an important role in maintaining the homeostasis of the heart by transmitting electric and mechanical signals. Changes in the architecture of the intercalated disc have been observed in dilated cardiomyopathy. Among cell-cell junctions in the intercalated disc, adherens junctions are involved in anchoring myofibrils and transmitting force. Nectins are Ca(2+)-independent, immunoglobulin-like cell-cell adhesion molecules that exist in adherens junctions. However, the role of nectins in cardiac homeostasis and integrity of the intercalated disc are unknown. Among the isoforms of nectins, nectin-2 and -4 were expressed at the intercalated disc in the heart. Nectin-2-knockout mice showed normal cardiac structure and function under physiological conditions. Four weeks after banding of the ascending aorta, cardiac function was significantly impaired in nectin-2-knockout mice compared with wild-type mice, although both nectin-2-knockout and wild-type mice developed similar degrees of cardiac hypertrophy. Banded nectin-2-knockout mice displayed cardiac fibrosis more evidently than banded wild-type mice. The disruption of the intercalated discs and disorganized myofibrils were observed in banded nectin-2-knockout mice. Furthermore, the number of apoptotic cardiac myocytes was increased in banded nectin-2-knockout mice. In the hearts of banded nectin-2-knockout mice, Akt remained at lower phosphorylation levels until 2 weeks after banding, whereas c-Jun N-terminal kinase and p38 mitogen-activated protein kinase were highly phosphorylated compared with those of wild-type mice. These results indicate that nectin-2 is required to maintain structure and function of the intercalated disc and protects the heart from pressure-overload-induced cardiac dysfunction.

Plasma tetrahydrobiopterin/dihydrobiopterin ratio: a possible marker of endothelial dysfunction

BACKGROUND

Although endothelium-dependent vasodilatation has been used as a marker of endothelial dysfunction (ED), there have been no reliable plasma markers for ED. Oxidative stress, which is a major determinant of ED, oxidizes tetrahydrobiopterin (BH4), an essential cofactor of endothelial type nitric oxide synthase (eNOS), and resulted in the relative deficiency of BH4.

METHODS AND RESULTS

In 163 patients with cardiovascular disorders, the plasma levels of BH4 and 7, 8-dihydrobiopterin (BH2) by high performance liquid chromatography were measured and compared with the flow-mediated (FMD) vasodilatory response of the brachial artery, which was measured by ultrasonography. The effects of atorvastatin on plasma pteridine levels and FMD were examined in patients with multiple coronary risk factors. There was a positive relationship between FMD and plasma BH4 levels and a negative relationship between FMD and plasma BH2 levels. Subsequently, a strong positive relationship between FMD and the BH4/BH2 ratio (r=0.585, P<0.0001) was found. Although we did not find any significant relationship between pteridine levels and individual traditional risk factors, the BH4/BH2 ratio in patients with more than 2 risk factors showed significant reductions compared with that in those without risk factors. Statin treatment improved FMD in association with an increase in the plasma BH4/BH2 ratio.

CONCLUSIONS

Plasma pteridine levels were associated with endothelial dysfunction in cardiovascular disorders.

Beneficial effects of exogenous tetrahydrobiopterin on left ventricular remodeling after myocardial infarction in rats: the possible role of oxidative stress caused by uncoupled endothelial nitric oxide synthase

BACKGROUND

Reactive oxygen species (ROS) is deeply involved in the process of ventricular remodeling after myocardial infarction (MI). Under oxidative stress, endothelial nitric oxide synthase (eNOS) can be converted to a ROS generator, because a relative lack of tetrahydrobiopterin (BH4), an essential cofactor for NO synthesis, leads to eNOS uncoupling. The uncoupled eNOS generates superoxide rather than NO. The possible role of ROS generated by eNOS in ventricular remodeling after MI was investigated.

METHODS AND RESULTS

Rats were treated with oral BH4 supplementation starting at 3 days before coronary artery ligation. At 4 weeks after MI, there was augmented superoxide production in association with reduced BH4/dihydrobiopterin (BH2) ratio and eNOS dimer/monomer protein ratio in the heart. Treatment with BH4 increased BH4/BH2 ratio and eNOS dimer/monomer ratio, and decreased superoxide production. In BH4-treated MI rats, left ventricular size was smaller, thickness of the non-infarcted posterior wall was thinner, and cardiac function was preserved compared with the control MI rats.

CONCLUSIONS

The present study suggested that ventricular remodeling process after MI leads to BH4 oxidation and resulted in uncoupled eNOS-derived superoxide generation, which further augmented the remodeling process and deteriorated cardiac function.

Transplantation of cardiotrophin-1–expressing myoblasts to the left ventricular wall alleviates the transition from compensatory hypertrophy to congestive heart failure in Dahl salt-sensitive hypertensive rats

OBJECTIVES

We investigated whether autologous transplantation of skeletal myoblasts (MB) transferred with cardiotrophin-1 (CT-1) gene could retard the transition to heart failure (HF) in Dahl salt-sensitive (DS) hypertensive rats.

BACKGROUND

Although MB is a therapeutic candidate for chronic HF, little is known about the efficiency of this strategy when applied in nonischemic HF. Cardiotrophin-1 has potent hypertrophic and survival effects on cardiac myocytes. We hypothesized that transplantation of CT-1-expressing myoblasts could provide cardioprotective effects against ventricular remodeling in DS hypertensive rats.

METHODS

The DS rats were fed a high salt diet for 6 weeks and developed left ventricular (LV) hypertrophy at 11 weeks. At this stage, animals underwent MB to the myocardium with skeletal myoblasts transferred with CT-1 gene using retrovirus (transplantation of CT-1-expressing myoblasts [MB + CT], n = 31) or myoblasts alone (MB, n = 31). The sham group rats were injected with phosphate-buffered saline (n = 24).

RESULTS

At 17 weeks, MB and MB + CT groups showed a significant alleviation of LV dilation and contractile dysfunction compared with the sham group. The degree of alleviation was significantly greater in the MB + CT group than the MB group (LV end-diastolic dimension: sham 7.06 +/- 0.14 mm, MB 6.51 +/- 0.16 mm, MB + CT 6.24 +/- 0.07 mm; fractional shortening: sham 32.1 +/- 1.4%, MB 38.5 +/- 1.5%, MB + CT 43.2 +/- 0.8%). Histological examination revealed that the myocyte size was 20% larger in the MB + CT group at 17 weeks than in the age-matched sham group. Upregulation of renin-angiotensin and endothelin systems during the transition to HF was attenuated by myoblast transplantation, and this effect was enhanced in the MB + CT group.

CONCLUSIONS

Transplantation of skeletal myoblasts combined with CT-1-gene transfer could be a useful therapeutic strategy for HF.

Cardiac myocytes are recruited by bone marrow-derived cells in intact murine heart

It is generally believed that the cardiac myocytes withdraw from the cell cycle shortly after birth and thereafter any loss of myocardial tissue cannot be repaired. However, recent reports indicate that cardiac myocytes can be regenerated by stem cells derived from bone marrow in the damaged hearts. In this study, we investigated whether bone marrow-derived cells can differentiate into cardiac myocytes in the intact hearts. We performed bone marrow transplantation from syngenic male mice to female c57/B6 mice. In female mice's hearts, the presence of cells from male mice was examined by FISH method that detects Y chromosome. Using the same samples, we also performed immunohistochemical staining with muscle specific antibodies. In the heart sections of female mice, there were some cells that were considered as differentiated myocytes derived from male bone marrow (0.01~0.09% of total myocytes) and the proportion of the cells increased as the period after bone marrow transplantation became longer (3 months after vs. 8 months after). These results suggest that, not only in the damaged heart but also in the intact heart, a portion of cardiac myocytes is recruited by bone marrow-derived cells.

Role of endogenous nitric oxide generation in the regulation of vascular tone and reactivity in small vessels as investigated in transgenic mice using synchrotron radiation microangiography

Nitric oxide (NO) produced by endothelial NO synthase (eNOS) plays a central role in regulation of vascular tone and reactivity. The purpose of this study is to clarify the basal tone and microvascular reactivity in eNOS-overexpressing transgenic (Tg) mice in vivo with a microangiography system using monochromatic synchrotron radiation (SR). The mouse femoral artery was cannulated, nonionic contrast media was injected, and microangiography was performed in hindlimbs of mice. Serial images of the small blood vessels (diameter <200 microm) were recorded by the SR microangiography system. At basal conditions, the diameter of tibial arteries in eNOS-Tg mice was larger than that of wild-type mice (179 +/- 8 versus 132 +/- 8 microm; P < 0.01). l-NAME treatment decreased the vessel diameter and canceled the difference in vessel diameters between two genotypes. Acetylcholine- and sodium nitroprusside-induced relaxations of small vessels were significantly reduced in Tg mice compared with wild-type mice (35.0 +/- 9.4 versus 61.6 +/- 6.7%, 85.0 +/- 10.2 versus 97.3 +/- 6.7% of the maximum relaxation, respectively). Our data provide the evidence that overproduced NO from endothelium reduces vascular tone and plays a pivotal role in regulation of vascular tone in small vessels. Furthermore, the reduced NO-mediated relaxation in small vessels of eNOS-Tg mice is demonstrated for the first time in vivo. SR microangiography allows us to evaluate the reactivity in small-sized vessels and appears to be a powerful tool for assessing the microvascular circulation in vivo.