Prognostic value of 6-min walk stress echocardiography in patients with interstitial lung disease.

BACKGROUND: The 6-min walk test (6MWT) provides prognostic information for patients with interstitial lung disease (ILD). Parameter determined by Doppler echocardiography after the 6MWT (6 MW stress echocardiography) is shown to be a predictor of future development of pulmonary hypertension in patients with connective tissue disease. However, the clinical utility of 6 MW stress echocardiography in predicting cardiopulmonary events in patients with ILD remains unknown. We examined whether parameters determined by 6 MW stress echocardiography independent predictors of adverse events in patients with ILD. METHODS: Echocardiographic examinations were performed in 68 consecutively enrolled patients with ILD (age, 65 ± 10 years, 65% men). A pressure gradient of tricuspid regurgitation (TRPG) and pulmonary vascular resistance (PVRecho) calculated using the following formula [PVRecho = (peak velocity of TR × 10/time-velocity integral of right ventricular outflow (RVOT-VTI)) + 0.16] were measured at baseline and at post 6MWT. Data for parameters of pulmonary functional tests and for 6MWT were collected. RESULTS: During a mean follow-up period of 22 ± 12 months, 22 patients experienced cardiopulmonary events. In univariate analysis, %VC, TRPG, PVRecho, TRPG post 6MWT, and PVRecho post 6MWT were significantly associated with cardiopulmonary events. Multivariate analysis using the Cox proportional hazards model indicated that %VC [hazard ratio (HR): 0.97, p = 0.009] and PVRecho post 6MWT (HR: 1.77, p = 0.004) were independent predictors of cardiopulmonary events in patients with ILD. CONCLUSIONS: In addition to parameters of pulmonary function tests, increased PVRecho post 6MWT is a significant predictor of cardiopulmonary events in patients with ILD. A 6 MW stress echocardiography is useful in assessing the risk of adverse events in patients with ILD.

Assessment of prognosis in immunoglobulin light chain amyloidosis patients with severe heart failure: a predictive value of right ventricular function.

Although the benefit of updated therapeutic regimens, including bortezomib, on the survival of immunoglobulin light chain (AL) amyloidosis patients with heart failure (HF) has been reported, predictors of mortality in the patients treated with the updated therapy remain unclear. We retrospectively enrolled AL amyloidosis patients who had severe HF at the time of diagnosis and received the updated therapy, including bortezomib (n = 19, 61 ± 6 years old, 68% male). Severe HF was defined as the presence of both NYHA functional class III or IV and BNP > 200 pg/ml or NT-pro-BNP > 900 pg/ml. One-year mortality rate during follow-up after commencement of the treatment was 37%. Left ventricular morphological parameters and indexes of left ventricular diastolic function on admission were similar in the non-survivors and survivors. However, non-survivors had higher incidences of atrial fibrillation and ventricular tachycardia, higher serum total bilirubin levels (1.34 ± 0.55 vs. 0.61 ± 0.29 mg/dl), higher right atrial volume index (RAVI 49.7 ± 29.9 vs. 27.3 ± 6.8 ml/m2), lower tricuspid annular peak velocities during systole (RVs' 8.0 ± 1.8 vs. 11.6 ± 3.7 cm/sec) and late diastole (RVa' 3.4 ± 0.9 vs. 11.4 ± 5.3 cm/sec), and larger inferior vena cava dimension (22.7 ± 6.4 vs. 16.3 ± 4.9 mm) than those in survivors. Kaplan-Meier curve analyses showed that larger RAVI and lower RVs' and RVa', but not left ventricular systolic/diastolic dysfunction, predicted higher mortality during 1-year follow-up. The present results suggest that the presence of right-sided heart abnormality on admission is associated with high 1-year mortality in AL amyloidosis patients with severe HF under the updated therapeutic regimens.

Soleal vein dilatation assessed by ultrasonography is an independent predictor for deep vein thrombosis after major orthopedic surgery.

BACKGROUND: Deep vein thrombosis (DVT) develops after major orthopedic surgery despite the current use of prophylaxis. DVT frequently develops in the soleal vein (SV) and might develop easily at the site of SV dilatation because of blood flow stasis. However, whether preoperative SV dilatation detected by ultrasonography predicts DVT after major orthopedic surgery remains unknown. OBJECTIVE: We examined whether SV dilatation detected by preoperative ultrasonography predicts DVT after major orthopedic surgery. METHODS: Ultrasonography was performed preoperatively and postoperatively in 243 patients with orthopedic diseases (mean age of 67±13 years, 77% women) who underwent total hip arthroplasty (THA, n=180) or total knee arthroplasty (TKA, n=63). Presence of DVT was diagnosed by ultrasonography and SV diameter ≥10mm was defined as SV dilatation. Patients with preoperative DVT were excluded. RESULTS: Sixty-nine patients (28%) developed postoperative DVT. SV dilatation was found in 24 patients (10%), and 16 (67%) of those patients had postoperative DVT. Multivariate logistic regression analysis showed that female gender [odds ratio (OR): 4.09, p=0.004], TKA (OR: 2.52, p=0.011), and SV dilatation (OR: 6.67, p<0.001), but not presence of comorbidities, medications, or plasma d-dimer value, independently predict postoperative DVT. Subgroup analyses according to the operation site showed that female gender (OR: 3.27, p=0.043) and SV dilatation (OR: 3.72, p=0.022) were independent predictors of postoperative DVT in the THA group. SV dilatation (OR: 12.0, p=0.027) was an independent predictor of postoperative DVT also in the TKA group. CONCLUSIONS: In addition to gender and TKA, SV dilatation detected by ultrasonography is an independent predictor of DVT after major orthopedic surgery. Determination of SV diameter by ultrasonography before major orthopedic surgery is useful for assessing the risk of postoperative DVT.

Development of a polarization-modulation spectroscopy system for the temporally resolved measurement of linear polarization in plasma emission.

A system to measure linear polarization in the HeI 21P-31D emission line (667.8 nm) was developed for application to plasma polarization spectroscopy. To verify the system performance, the normalized Stokes parameters were evaluated. A measurement error of less than 1% with a time resolution of 1 ms was achieved for monochromatic light in the state of complete linear polarization.

Intra- and Inter-rater Agreement on Magnetic Resonance Imaging Evaluation of Rotator Cuff Integrity After Repair.

PURPOSE: To investigate the intra- and inter-rater agreement of magnetic resonance imaging (MRI) evaluations of rotator cuff integrity at 6 and 24 months after arthroscopic rotator cuff repair (ARCR). METHODS: Three shoulder surgeons reviewed 68 MRI scans from 34 patients who had undergone ARCR and MRI examination at both 6 and 24 months after surgery. Postoperative rotator cuff integrity was investigated by using Owen, Sugaya, and Hayashida classifications to determine whether the rotator cuff was intact or whether there was a partial-thickness retear or full-thickness retear and Burks score to assess tendon appearance. Multirater kappa statistics were used to measure intra- and inter-rater agreement. Kappa values were interpreted according to guidelines adapted from the work of Landis and Koch. RESULTS: All classifications had similar intra- and inter-rater agreement (κ = 0.14 to 0.67, 0.23 to 0.60, respectively), but no intra- or inter-rater agreement scored "excellent." Inter-rater agreement after ARCR was higher at 24 months (κ = 0.31 to 0.60) than at 6 months (κ = 0.23 to 0.44) in all evaluations. Reviewers identified full-thickness retears with a moderate to good degree of inter-rater agreement in all evaluations, at both 6 months (κ = 0.42 to 0.73) and 24 months (κ = 0.61 to 0.80) after ARCR. However, poor inter-rater agreement (κ = 0.13 to 0.19) was found in the identification of partial-thickness retears in all evaluations at 6 months after ARCR. CONCLUSIONS: Shoulder surgeons showed better intra- and inter-rater agreement in predicting full-thickness tears compared with partial-thickness tears. The inter-rater agreement at 24 months after ARCR was superior to that at 6 months in predicting not only full-thickness retear but also partial-thickness retear. MRI evaluation of rotator cuff integrity at 6 months after ARCR may be less reliable, regardless of which classification system is used. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Pulmonary vascular resistance estimated by Doppler echocardiography predicts mortality in patients with interstitial lung disease.

BACKGROUND: Pulmonary hypertension (PH) is a strong predictor of mortality in patients with interstitial lung disease (ILD). However, patients with ILD often have poor outcomes even in the absence of PH. Pulmonary vascular resistance (PVR) assessed by right heart catheterization is a predictor of mortality in patients with ILD. However, the clinical utility of PVR assessed by Doppler echocardiography (PVRecho) as a predictor of the outcome in patients with ILD remains unclear. The aim of this study was to examine whether PVRecho independently predicts mortality in patients with ILD. METHODS: Echocardiographic examinations were performed in 133 consecutively enrolled patients with ILD (age, 67±9 years; 53% men). Tricuspid annular plane systolic excursion (TAPSE) was measured, and PVRecho was calculated by the following formula: PVRecho=[TRV×10/time-velocity integral of right ventricular outflow (RVOT-VTI)]+0.16. Data for parameters of pulmonary functional tests and for serum biomarkers, which were measured within 3 months before or after the echocardiographic examinations, were collected. RESULTS: During a mean follow-up period of 18±7 months, 13 patients died due to respiratory failure (n=10), heart failure (n=1), or unknown causes (n=2). In univariate analysis, body mass index, idiopathic pulmonary fibrosis, use of an antifibrotic drug (AD), RVOT-VTI, PVRecho, percentage of predicted vital capacity (%VC), percentage of predicted forced expiratory volume in 1second, and percentage of predicted diffusion capacity of the lungs for carbon monoxide (%DLco), but not TAPSE or serum biomarkers, were significantly associated with mortality. Cox proportional hazard multivariate analysis indicated that %VC [hazard ratio (HR): 0.92, p=0.001], use of AD (HR: 4.05, p=0.043), and PVRecho (HR: 3.79, p=0.029) independently predict mortality in patients with ILD. Replacement of %VC with %DLco in the multivariate analysis did not change the results: %DLco (HR: 0.90, p=0.001), use of AD (HR: 7.53, p=0.029), and PVRecho (HR: 3.65, p=0.020). CONCLUSIONS: In addition to parameters of pulmonary function tests and use of AD, increased PVRecho is an independent predictor of mortality in patients with ILD who were evaluated for screening of PH by echocardiography.

Clinical results of surgical treatment for femoral neck fractures with the Targon® FN.

84 cases (male 15 cases, female 69 cases) of intracapsular femoral neck fractures treated with the Targon® FN (TFN) were available for review. Mean patient age was 74.0 years (range 36-100 years). 55 fractures were undisplaced whereas 29 were displaced. Mean follow-up term was 16.4 months. We surveyed patient mobility before injury and after operation as well as postoperative complications. On a four-stage mobility scale we found 3/55 patients with undisplaced fractures loosing mobility by more than one grade (5.5%), whereas 5/29 (17.2%) displayed this kind of functional decline after displaced fractures. Overall postoperative complication rate was 10.7% (9 cases). These complications included nonunion (1 case), avascular necrosis (7 cases) and peri-implant fracture (1case). Internal fixation with the TFN seems to have an acceptable complication rate in both undisplaced and displaced fractures compared to other recent studies.

Pericardial Effusion and Multiple Organ Involvement Are Independent Predictors of Mortality in Patients with Systemic Light Chain Amyloidosis.

OBJECTIVE: Left ventricular (LV) functions assessed by echocardiography and cardiac biomarkers are strong predictors of mortality in patients with systemic light chain (AL) amyloidosis. However, most previous studies have been conducted in Western countries, and the predictors of mortality in Asian patients with AL amyloidosis have not been characterized. To address this issue, we aimed to determine the predictors of mortality in Asian patients with biopsy-confirmed AL amyloidosis. METHODS: We retrospectively enrolled 31 patients (59±11 years, 55% men) in whom AL amyloidosis was confirmed by biopsies from cardiac or non-cardiac tissues. Of these patients, 15 (48%) met the international echocardiographic criteria for cardiac amyloidosis (mean LV wall thickness >12 mm without other causes of LV hypertrophy). RESULTS: During a mean follow-up period of 21±20 months, 15 patients died. Non-survivors had a higher number of involved organs, lower e', and higher rates of E/e' >15, pericardial effusion (PE), low voltage on an electrocardiogram and a New York Heart Association (NYHA) functional class ≥ III, compared with survivors. In multivariate analysis, a NYHA functional class ≥ III (p=0.024) and cardiac involvement (p=0.032) were independent predictors of PE in patients with AL amyloidosis. Multivariate Cox proportional hazard analysis indicated that PE (hazard ratio: 21.9, p=0.025) and the number of involved organs (hazard ratio: 2.8, p=0.015), but not LV diastolic parameters of tissue Doppler echocardiography, independently predict mortality in patients with AL amyloidosis. CONCLUSION: PE and multiple organ involvement, compared with e' and E/e', are stronger predictors of mortality in patients with AL amyloidosis. The advanced disease stage of AL amyloidosis might underlie the strong association between PE and a poor outcome.

Intervendor Variabilities of Left and Right Ventricular Myocardial Velocities among Three Tissue Doppler Echocardiography Systems.

BACKGROUND: Whether an intervendor discordance of myocardial velocities determined by tissue Doppler echocardiography (TDE) can be generalized remains unclear. We compared intervendor variabilities of left ventricular (LV) and right ventricular (RV) myocardial velocities among three TDE systems. METHODS: Examinations with TDE were performed in 41 healthy subjects and 11 patients with cardiovascular risk factors (CVR) using α-7 (V1, Hitachi Aloka Medical), Artida (V2, Toshiba Medical Systems), and Vivid E9 (V3, GE Healthcare) on the same day. Peak systolic (s'), early diastolic (e'), and late diastolic (a') myocardial velocities at medial and lateral sites of the mitral annulus and lateral site of the tricuspid annulus were measured using both pulsed-wave TDE and color TDE. Intra-observer and inter-observer variabilities were determined in 10 subjects and test-retest variability in 14 subjects. RESULTS: As for test-retest variability, reproducibilities of LV and RV myocardial velocities determined by pulsed-wave TDE and color TDE were relatively low but comparable between V1, V2, and V3. Myocardial velocities in healthy subjects determined by both pulsed-wave TDE and color TDE were significantly different among the three TDE systems. Myocardial velocities by pulsed-wave TDE in V3 were 2-12% lower (P < 0.05) than those by V2 and 5-14% lower (P < 0.05) than those by V1. Similar differences in myocardial velocities determined by both pulsed-wave TDE and color TDE were found in patients with CVR. CONCLUSIONS: LV and RV myocardial velocities determined by both pulsed-wave TDE and color TDE are vendor dependent, and reproducibility of the myocardial velocities determined by both TDE systems is relatively low.

Complications and fixation techniques of trochanteric fractures with the TARGON(®) PF.

The purpose of this study was to analyse clinical results of elderly patients with trochanteric fractures that were treated with use of TARGON(®) PF nail. Overall, 494 patients (113 males) were available for this study. On the basis of Jensen classification, there were 76 cases in type I, 164 cases in type II, 70 in type III, 129 in type IV and 55 in type V. (1) Sliding amount of lag screw in relation to the Jensen classification, (2) sliding amount of lag screw according to the Ikuta's classification that categorises the reduction in lateral view in three, Subtype A, Subtype N and Subtype P, (3) sliding amount of lag screw in correlation between Jensen classification and Ikuta's classification and (4) postoperative complications (9 cases; 1.7%) were assessed. Cut-out and back-out cases were seen in 6 cases (1.1%), and these severe complications were evaluated in details. In correlation between Jensen classification and Ikuta's classification, the excessive sliding of lag screw was prominent with the Subtype P, which was preoperatively in Jensen type III or V. Cut-out or back-out cases were caused either from (1) Subtype P that were preoperatively Jensen types III or V, or from (2) the fracture where there was bony defect anteriorly. Therefore, special care must be taken for these types.

Detection of QT prolongation through approximation of the T wave on Gaussian mixture modeling.

BACKGROUND: To establish a simple and accurate method for the automated identification of the end of a T wave, we approximated electrocardiograph (ECG) traces using a Gaussian mixture model in conjunction with a split-and-merge expectation-maximization algorithm. METHODS AND RESULTS: A total of 286 ECG traces of heart beats of 50 healthy men were used as control data and ECGs from 15 subjects recorded before and after 400mg oral moxifloxacin as positive controls. An experienced cardiologist determined the reference points by visual inspection of the original ECGs. The primary estimated point for the end of the T wave was selected as the point 2 ms before the point at which the gradient of the approximated wave was not steeper than the common threshold value. This point was then adjusted by applying modification rules proposed by an experienced cardiologist. The absolute value of the average interval between the resulting final estimated point and the manually selected reference point was 1.8±7.7 ms for the control data. After treatment with moxifloxacin, the average QT interval, corrected by Bazett's formula, showed a 17.2±27.1 ms prolongation with a lower bound of the 95% confidence interval of 4.9 ms. CONCLUSIONS: When the modification rules were applied, the accuracy of QT measurement was improved, and the present system was capable of detecting QT prolongation correctly.

Combinational risk factors of metabolic syndrome identified by fuzzy neural network analysis of health-check data.

BACKGROUND: Lifestyle-related diseases represented by metabolic syndrome develop as results of complex interaction. By using health check-up data from two large studies collected during a long-term follow-up, we searched for risk factors associated with the development of metabolic syndrome. METHODS: In our original study, we selected 77 case subjects who developed metabolic syndrome during the follow-up and 152 healthy control subjects who were free of lifestyle-related risk components from among 1803 Japanese male employees. In a replication study, we selected 2196 case subjects and 2196 healthy control subjects from among 31343 other Japanese male employees. By means of a bioinformatics approach using a fuzzy neural network (FNN), we searched any significant combinations that are associated with MetS. To ensure that the risk combination selected by FNN analysis was statistically reliable, we performed logistic regression analysis including adjustment. RESULTS: We selected a combination of an elevated level of γ-glutamyltranspeptidase (γ-GTP) and an elevated white blood cell (WBC) count as the most significant combination of risk factors for the development of metabolic syndrome. The FNN also identified the same tendency in a replication study. The clinical characteristics of γ-GTP level and WBC count were statistically significant even after adjustment, confirming that the results obtained from the fuzzy neural network are reasonable. Correlation ratio showed that an elevated level of γ-GTP is associated with habitual drinking of alcohol and a high WBC count is associated with habitual smoking. CONCLUSIONS: This result obtained by fuzzy neural network analysis of health check-up data from large long-term studies can be useful in providing a personalized novel diagnostic and therapeutic method involving the γ-GTP level and the WBC count.

A new manual method for assessing elbow valgus laxity.

BACKGROUND: A screening of ulnar collateral ligament insufficiency is required for overhead throwers, since secondary pathologic changes result from an increased elbow valgus laxity. We developed a new manual method for assessing elbow valgus laxity and investigated the reliability of this method and its correlation with ultrasonographic assessment. METHODS: We defined elbow valgus laxity as the difference between the shoulder external rotation angle (ER angle) measured with the elbow in 90 degrees flexion and that measured with the elbow in extension because ER angle measured with the elbow in 90 degrees flexion includes elbow valgus laxity and ER angle with the elbow in extension does not include it. ER angle measurement with the elbow in extension involved the use of a custom arm holder. Three examiners each measured elbow valgus laxity by the new method in 5 healthy volunteers. Intraobserver and interobserver reliability was evaluated by calculating the intraclass correlation coefficient. We then assessed 19 high-school baseball players with no complaints of shoulder or elbow pain. Elbow ultrasonography was performed with a 10-MHz linear transducer with the elbow in 90 degrees flexion, and the forearm in the neutral position, and the width of the medial joint space at the level of the anterior bundle was measured. Elbow valgus laxity assessed by ultrasonography was defined as the difference between the medial joint space width with gravity stress and that without gravity stress. Increased elbow valgus laxity assessed by both our method and ultrasonography was defined as the difference between the laxity of the elbow on the throwing side and that on the contralateral side. Pearson's correlation coefficient (r) was calculated to evaluate the relationship between increased elbow valgus laxity obtained by our manual method and that by ultrasonography. RESULTS: Intraobserver reliability ranged from 0.92 to 0.98, and interobserver reliability was 0.70. The increased elbow valgus laxity assessed by our method was significantly correlated with that assessed by ultrasonographic assessment (P = 0.019, r = 0.53). CONCLUSIONS: Elbow valgus laxity can be assessed by our method. This method may be useful for screening for insufficiency of the ulnar collateral ligament.

Relation of a common variant of the adiponectin gene to serum adiponectin concentration and metabolic traits in an aged Japanese population.

Adiponectin is an adipocyte-derived protein that is down-regulated in obesity-linked disorders. Variants of the adiponectin gene (ADIPOQ) have been shown to affect adiponectin level. We have now examined the relation of polymorphisms of ADIPOQ to adiponectin concentration and to metabolic disorders in the Kita-Nagoya Genomic Epidemiology study, a population-based study of elderly Japanese. The genomic region including ADIPOQ was genotyped for 30 single nucleotide polymorphisms in 500 subjects of a screening population with the use of a fluorescence- or colorimetry-based allele-specific DNA primer-probe assay system. Four polymorphisms were then selected for genotyping in an additional 2797 subjects. Serum adiponectin level was negatively associated with metabolic abnormalities after adjustment for age and sex. The minor alleles of the rs1656930, Ile164Thr, and rs9882205 polymorphisms were associated with a low serum adiponectin level. Whereas the minor alleles of rs1656930 and rs9882205 were common (minor allele frequency of 6.2 and 38.5%, respectively), that of Ile164Thr was rare (0.9%). The minor allele of rs1656930 was positively associated with systolic blood pressure and the prevalence of hypertension. The association of rs1656930 with adiponectin level was replicated in an independent population. A subject with the 164Thr/Thr genotype had an extremely low serum adiponectin level (0.6 µg/ml) and the phenotype of metabolic syndrome. Our results suggest that a common variant of ADIPOQ, the minor allele of rs1656930, is associated with hypoadiponectinemia and hypertension. Screening for a common genetic background underlying low adiponectin levels might provide important information for assessment and management of metabolic disorders.

Effects of aldosterone on Cx43 gap junction expression in neonatal rat cultured cardiomyocytes.

BACKGROUND: The renin-angiotensin-aldosterone system affects cellular morphology and function in the heart under a variety of pathologic conditions. In the present study the effects of aldosterone on the expression of connexin (Cx) 43 gap junctions in cardiomyocytes were investigated. METHODS AND RESULTS: Cultured rat ventricular myocytes were exposed to aldosterone for 24 h. The protein and mRNA expression of Cx43 was estimated. Propagation of excitation was visualized by a multiple electrode array system. Treatment of the myocytes with 10(-8) mol/L aldosterone resulted in a significant upregulation of Cx43 (by approximately 1.5-fold in protein and by approximately 1.2-fold in mRNA). The immunoreactive signal of Cx43 was also increased. Conduction velocity (CV) was increased by approximately 24%. Treatment of the myocytes with aldosterone at higher concentrations (10(-6)-10(-4) mol/L) caused a significant downregulation of Cx43 protein (by approximately 0.3-fold) without affecting Cx43 mRNA levels, and decreased the CV by ~23%. The Cx43 upregulation and CV acceleration at 10(-8) mol/L aldosterone were prevented by pretreatment with eplerenone, but unaffected by mifepristone. Pretreatment of the myocytes with eplerenone or mifepristone did not prevent the Cx43 downregulation by aldosterone at 10(-6)-10(-4) mol/L. CONCLUSIONS: Aldosterone may be involved in arrhythmogenic gap junction remodeling through its dual effects on the expression of Cx43.

Perinatal loss of Nkx2-5 results in rapid conduction and contraction defects.

Homeobox transcription factor Nkx2-5, highly expressed in heart, is a critical factor during early embryonic cardiac development. In this study, using tamoxifen-inducible Nkx2-5 knockout mice, we demonstrate the role of Nkx2-5 in conduction and contraction in neonates within 4 days after perinatal tamoxifen injection. Conduction defect was accompanied by reduction in ventricular expression of the cardiac voltage-gated Na+ channel pore-forming alpha-subunit (Na(v)1.5-alpha), the largest ion channel in the heart responsive for rapid depolarization of the action potential, which leads to increased intracellular Ca2+ for contraction (conduction-contraction coupling). In addition, expression of ryanodine receptor 2, through which Ca2+ is released from sarcoplasmic reticulum, was substantially reduced in Nkx2-5 knockout mice. These results indicate that Nkx2-5 function is critical not only during cardiac development but also in perinatal hearts, by regulating expression of several important gene products involved in conduction and contraction.

T-type Ca2+ channel blockers prevent cardiac cell hypertrophy through an inhibition of calcineurin-NFAT3 activation as well as L-type Ca2+ channel blockers.

T-type Ca2+ channels (TCCs) are involved in cardiac cell growth and proliferation in cultured cardiomyocytes. Underlying molecular mechanisms are not well understood. In this study, we investigated the role of TCCs in signal transduction in cardiac hypertrophy compared with L-type Ca2+ channels (LCCs). Cardiomyocytes dissociated from neonatal mouse ventricles were cultured until stabilization. Cell hypertrophy was induced by reapplication of 1% fatal bovine serum (FBS) following a period (24 h) of FBS depletion. Cell surface area increased from 862+/-73 microm2 to 2153+/-131 microm2 by FBS stimulation in control (250+/-1.8%). T-type Ca2+ current (I(CaT)) was inhibited dose-dependently by kurtoxin (KT) and efonidipine (ED) with IC50 0.07 microM and 3.2 microM, respectively in whole-cell voltage clamp. On the other hand, 1 microM KT which inhibits I(CaT) over 90% did not effect on L-type Ca2+ current (I(CaL)). 10 microM ED had the ability of I(CaL) blockade as well as that of I(CaT) blockade. 3 microM nisoldipine (ND) suppressed I(CaL) by over 80%. The increase in cell surface area following reapplication of FBS as observed in control (250+/-1.8%) was significantly reduced in the presence of 1 microM KT (216+/-1.2%) and virtually abolished in the presence of 10 microM ED (97+/-0.8%) and 3 microM ND (80+/-1.1%). Hypertrophy was associated with an increase in BNP mRNA of 316+/-3.6% in control and this increase was reduced as well in the presence of 1 microM KT (254+/-1.8%) and almost abolished in the presence of 10 microM ED (116+/-1.1%) and 3 muM ND (93+/-0.8%). Immunolabeling showed that translocation of nuclear factor of activated T cells (NFAT3) into the nucleus in response to FBS stimulation was markedly inhibited by either KT or ED as well as ND. Calcineurin phosphatase activity was upregulated 2.2-fold by FBS, but KT, ED and ND decreased this upregulation (1.7-fold, 0.8-fold, and 0.7-fold with KT, ED and ND respectively). These results suggest that blockade of Ca2+ entry into cardiomyocytes via TCCs may block pathophysiological signaling pathways leading to hypertrophy as well as via LCCs. The mechanism may be the inhibition of calcineurin-mediated NFAT3 activation resulting in prevention of its translocation into the nucleus.

Prognostic significance of circadian variability of RR and QT intervals and QT dynamicity in patients with chronic heart failure.

BACKGROUND: In patients with chronic heart failure (CHF), circadian variability of RR and QT intervals may be altered because of neurohumoral activation and functional and structural remodeling of the heart. OBJECTIVE: The aim of this study was to evaluate the prognostic significance of circadian variability of the RR and QT intervals and QT dynamicity (QT/RR slope) in CHF patients. METHODS: We prospectively enrolled 121 patients with stable CHF in sinus rhythm (age 67 +/- 14 years, mean +/- SD; range 34 to 87 years). The RR, QT, and rate-corrected QT (QTc) intervals and the QT/RR slope measured from 24-hour Holter electrocardiogram were fitted by cosine curves. RESULTS: During the follow-up period of 34 +/- 17 months, 40 (33%) patients died of cardiac causes, 10 of which were sudden. All patients showed significant circadian rhythms in the RR, QT, and QTc intervals and the QT/RR slope by cosine-curve fitting. In addition to the expected higher heart rate, longer QT interval, and steeper QT/RR slope, we found that patient who died of cardiac causes had reduced circadian variability of QT interval (10 +/- 10 ms vs 21 +/- 13 ms) and a later maximum RR interval (4.1 +/- 0.9 AM vs 2.3 +/- 2.1 AM) compared with survivors, among many other statistically significant circadian parameter differences. These 2 parameters were independent predictors of cardiac death in multivariate Cox proportional hazards regression analysis. CONCLUSION: Circadian variability analyses of Holter-derived RR and QT intervals may provide prognostic information beyond that provided by 24-hour averages of these parameters.

Aldosterone modulates I(f) current through gene expression in cultured neonatal rat ventricular myocytes.

Mineralocorticoid receptor (MR) antagonists decrease the incidence of sudden cardiac death in patients with heart failure, as has been reported in two clinical trials (Randomized Aldactone Evaluation Study and Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival Study). Aldosterone has been shown to increase the propensity to arrhythmias by changing the expression or function of various ion channels. In this study, we investigate the effect of aldosterone on the expression of hyperpolarization-activated current (I(f)) channels in cultured neonatal rat ventricular myocytes, using the whole cell patch-clamp technique, real-time PCR, and Western blotting. Incubation with 10 nM aldosterone for 17-24 h significantly accelerates the rate of spontaneous beating by increasing diastolic depolarization. I(f) current elicited by hyperpolarization from -50 to -130 mV significantly increases aldosterone by 10 nM (by 1.9-fold). Exposure to aldosterone for 1.5 h increases hyperpolarization-activated cyclic nucleotide-gated (HCN) 2 mRNA by 26.3% and HCN4 mRNA by 47.2%, whereas HCN1 mRNA expression remains unaffected. Aldosterone (24-h incubation) increases the expression of HCN2 protein (by 60.0%) and HCN4 protein (by 84.8%), but not HCN1 protein. MR antagonists (1 microM eplerenone or 0.1 microM spironolactone) abolish the increase of I(f) channel expression (currents, mRNA, and protein levels) by 10 nM aldosterone. In contrast, 1 microM aldosterone downregulated I(f) channel gene expression. Glucocorticoid receptor antagonist (100 nM RU-38486) did not affect the increase of I(f) current by 10 nM aldosterone. These findings suggest that aldosterone in physiological concentrations upregulates I(f) channel gene expression by MR activation in cardiac myocytes and may increase excitability, which may have a potential proarrhythmic bearing under pathophysiological conditions.

Upregulation of KCNE1 induces QT interval prolongation in patients with chronic heart failure.

BACKGROUND: Prolongation of the action potential duration (APD) is observed in ventricular myocytes isolated from the failing heart. The rapid component (I(Kr)) and the slow component (I(Ks)) of the delayed-rectifier potassium current (I(K)) are major determinants of the APD, but less information is available on the genomic modulation of I(K) in the remodeled human heart. The aim of the current study was to examine the relationship between I(K) transcripts and QT interval in surface electrocardiogram in patients with chronic heart failure (CHF). METHODS AND RESULTS: Total RNA was extracted from right ventricle endomyocardial biopsy samples in 21 CHF patients (age: 53+/-4 years, mean +/- SEM). The KCNH2 and KCNQ1 levels did not differ significantly between controls (New York Heart Association (NYHA) I, n=10) and CHF patients (NYHA II or III, n=11), whereas the KCNE1 level was significantly higher in CHF patients than in controls (relative mRNA levels normalized to GAPDH expression: 6.16+/-0.31 vs 7.70+/-0.46, p<0.05). The KCNE1/KCNQ1 ratio was higher in CHF patients than in controls (0.92+/-0.02 vs 1.06+/-0.05, p<0.05) and the KCNE1-KCNQ1 ratio was positively correlated with QT interval (r=0.70, p<0.05). Increasing the KCNE1 concentration caused a shift in activation voltage and slowed the activation kinetics of the KCNE1-KCNQ1 currents expressed in Xenopus oocytes. Prolongation of the APD and decrease in I(Ks) with increasing the amount of KCNE1 concentration were well predicted in a computer simulation. CONCLUSIONS: In mild-to-moderate CHF patients, the relative abundance of KCNE1 compared to KCNQ1 genes, at least in part, might contribute to the preferential prolongation of QT interval through reducing the net outward current during the plateau of the action potential.