Left Ventricular Internal Dimension In Systole Research Articles

English

To explore the effect of the angiotensin type 1 (AT-1) receptor antagonist, Irbesartan, on myocardial interstitial fibrosis in rats with diabetic cardiomyopathy (DCM). Thirty-nine male wistar rats were injected intraperitoneally with streptozotocin (STZ) (55 mg/kg, once) to establish a DCM animal model. After 12 weeks, the rats with blood glucose higher than 16.7 mmol/L, as well as polydipsiaa€hyperphagia and polyuria, were randomly divided into three groups: control, Irbesartan and A779+Irbesartan group. Rats in control were infused normal saline, in Irbesartan were infused Irbesartan (50 mg/kg) and in A779+Irbesartan were infused Irbesartan and were injected with A779 (100 ng/kg) once daily. At the end of the experiment, left ventricular internal dimension systole (LVIDs)a€left ventricular internal dimension diastole (LVIDd)a€E/Aa€left ventricular ejection fraction (LVEF)a€shortening fraction (FS) were measured. Then collagen content and the messenger ribonucleic acid (mRNA) expression of angiotensin-convertion enzyme 2 (ACE2) were detected. At the end of the experiment, the LVIDs, LVIDd and the collagen content of Irbesartan and A779+Irbesartan were significantly lower than control (P<0.01), E/A, FS, LVEF and the expression of ACE2 mRNA of Irbesartan and A779+Irbesartan were higher than control (P<0.01). The LVIDs, LVIDd and collagen content of A779+Irbesartan were higher than Irbesartan (P<0.05), E/A, FS, LVEF of A779+Irbesartan were lower than Irbesartan (P<0.05). However, there was no significant difference in the expression of ACE2 mRNA between Irbesartan and A779+Irbesartan. Irbesartan amelioorates myocardial interstitial fibrosis via angiotensin-(1-7) (Ang-(1-7)) Key words: Irbesartan, angiotensin-(1-7), angiotensin-convertion enzyme-2, A779, diabetes mellitus, cardiomyopathy.

Abstract 1331: Myocardial Function Alterations Correlate to Cardiac Fibrosis and Upregulation of Profibrotic Signaling in Plasminogen Activator Inhibitor-1 Deficient Mice

Cardiac fibrosis is a common sequelae of cardiac injury and has deleterious functional consequences impacting cardiac filling, function and rhythm. Plasminogen activator inhibitor-1 (PAI-1) has been implicated in the pathogenesis of tissue fibrosis in mice. To investigate the longitudinal effect of PAI-1 on cardiac structure and function, M-mode echocardiography was employed to examine cardiac function in PAI-1 deficient (PAI-1 −/− ) and wild-type (WT) control mice in four age groups (6,12,18, 24 months). Eighteen month old PAI-1 −/− mice exhibited reduced left ventricular (LV) diastolic internal dimension ( p =0.0118) and a trend towards increased LV posterior wall (LVPW) thickness, compared to WT. Two year old PAI-1 −/− mice showed increased diastolic and systolic LVPW thickness ( p =0.0127 and p =0.0212, respectively), reduced diastolic and systolic LV internal dimension ( p =0.0486 and p =0.0124), but with preserved LV fractional shortening compared to WT. Histological examination of cardiac sections revealed fibrosis on the anterior epicardial surface of the hearts in 18 month old PKO, which in 26 month old mice had become confluent with extensive (10 –17% by area) epicardial, perivascular, and interstitial distribution (compared to none in WT). Real time polymerase chain reaction (RT-PCR) revealed upregulation of transforming growth factor beta (TGF-β) and fibroblast growth factor 2 in PAI-1 −/− compared to WT ( p =0.0234 and p =0.037, respectively). Immunofluoresence confirmed this finding with bright TGF-β staining localized in the media of intra-myocardial arterioles, and phosphorylated SMAD2/3, the downstream TGF-β signaling mediator, in areas of fibrosis. Thoracic aortic cells from aged (18 –24 month) PKO and WT mice were grown in culture, with RT-PCR revealing 4 fold increased TGF-β and 17 fold increased SMAD3 ( p &lt;0.05 for both) RNA levels in PAI-1 −/− , supplying additional evidence for upregulation of a profibrotic TGF-β/SMAD tissue signaling pathway. The present study is one of the first to elucidate some of the functional consequences and relevant molecular signaling pathways related to aging and PAI-1 deficiency mediated cardiac fibrosis.

Midterm Follow-up of Robotic Biventricular Pacing Demonstrates Excellent Lead Stability and Improved Response Rates

: Robotically assisted left ventricular (LV) lead placement is an effective minimally invasive rescue procedure for cardiac resynchronization in the setting of failed coronary sinus lead insertion. The long-term response rate and durability of this technique has not been reported. The authors evaluated the midterm outcome of biventricular pacing performed with robotically placed LV leads. : Forty-two patients underwent implantation of LV epicardial leads using robotic assistance and the posterior approach. Half of the patients had prior cardiac surgery. All leads were placed in an optimal site along the posterolateral surface of the LV. The patients were prospectively followed up for clinical response, LV reverse remodeling, and LV lead stability over a mean period of 16.7 ± 9.5 months (range, 3-34 months). A multivariate Cox proportional hazards model was used to determine predictors of response. : All patients had successful LV lead placement with no postoperative mortality. Statistically significant improvements in left ventricular ejection fraction, NYHA heart failure class, systolic left ventricular internal dimension index, and diastolic left ventricular internal dimension index. The 3-month clinical response rate was 81% and dropped to 71% at average maximal follow-up. Multivariate analysis of 9 variables revealed only LVEF greater than 15% and absence of pulmonary hypertension to be predictors of response. No difference in operative time, response rate, or LV lead stability was detected when primary versus reoperative cases were compared. : Robotic LV lead placement is a reliable technique for optimal lead placement with durable long-term results.

Correlation Between Levels of N-terminal Pro-B-Type Natriuretic Peptide and Degrees of Heart Failure

BackgroundThe N-terminal fragment of pro Brain Natriuretic Peptide (NT-pro BNP) is a neuro-hormone synthesized in the cardiac ventricles in response to increased wall tension. The purpose of this study was to assess the correlation between the NT-pro BNP levels and the New York Heart Association function class (NYHA Fc) of dyspnea and echocardiographic findings for the patients who visited our cardiology departments.MethodsFrom October, 2002 to April, 2003, serum NT-pro BNP levels were measured in 348 patients who visited the Samsung Medical Center and the Jong Koo Lee Heart Clinic.ResultsThe NT-pro BNP levels were increased with the progression of NYHA Fc of dyspnea (p<0.001 by ANOVA), the increase in the systolic left ventricular internal dimension (p<0.05), and the decrease in the ejection fraction (p<0.01). For the NYHA Fc I patients, the NT-pro BNP levels were positively correlated with age (p<0.001) and left atrial size (p<0.001). For the patients with ischemic heart disease, the NT-pro BNP levels were also positively correlated with the NYHA Fc (p<0.001 by ANOVA). The NT-pro BNP levels were increased with the increase in the systolic (p<0.001) and diastolic pressure (p=0.017), the left ventricular internal dimension as well as the decrease in the ejection fraction (p<0.001). The area under the receiver operating characteristic (ROC) curve for the NT-pro BNP levels was 0.994 (95% confidence interval, 0.979-0.999), and the most reliable cut-off level for the NT-pro BNP was 293.6 pg/mL.ConclusionThe NT-pro BNP levels were positively correlated with the NYHA Fc of dyspnea and the systolic dysfunction for the patients who visited our cardiology departments. A 300 pg/mL value for the NT-pro BNP cut-off point appears to be a sensitive level to differentiate dyspnea originating from an ailing heart or not for the patients who visited our cardiology departments.

Resting and dobutamine stress echocardiographic factors associated with the development of occult dilated cardiomyopathy in healthy Doberman pinscher dogs.

In 29 healthy Doberman Pinschers, echocardiographic parameters evaluating systolic and diastolic function were examined prospectively at rest and during dobutamine constant rate infusion (5 micrograms/kg/minute) to determine if any parameters were associated with the development of occult dilated cardiomyopathy (DCM). A resting echocardiogram was repeated 1 year later to determine which dogs had met our criteria for occult DCM. Six dogs developed occult DCM during the follow-up period. Univariate logistic regression analysis showed that at rest, an increased left ventricular internal dimension in systole (LVID-S) (P = .02), preejection period (PEP) (P = .03), ratio of PEP to left ventricular ejection time (P = .02), and isovolumic relaxation time (P = .02) were significantly associated with the development of occult DCM. During dobutamine stress echocardiography (DSE), high LVID-S (P = .02) and systolic wall stress index (P = .04) and reduced fractional shortening (P = .02) and ratio of peak early to late diastolic mitral filling velocity (E/A) (P = .05) were associated with the development of occult DCM. Multiple logistic regression showed that LVID-S (P = .002) and E/A (P = .002) measured during dobutamine infusion also were associated with the development of occult DCM. Reclassification based on the DSE data was not significantly different than reclassification based on the resting echocardiographic data. Resting echocardiography and DSE have the potential to be clinically applicable screening tests for very early systolic and diastolic dysfunction in Doberman Pinschers, heralding the onset of occult DCM as it is currently defined.

Echocardiographic parameters and indices in the normal beagle dog.

M-mode and two-dimensional echocardiographic measurements were made from the right sternal border of 50 healthy Beagles (25 males and 25 females) approximately 7 months old. The dogs were conscious and standing during the investigation. The following parameters, in systole and diastole, were measured on the echocardiographic images: left ventricular posterior wall thickness (LVWT); intraventricular septum thickness (IST); left ventricular internal dimension (LVID); and circumference (LVC). Fractional shortening (FS) and ejection fraction (EF) were also calculated. Mean, standard deviation, range and coefficient of variation are reported for each echocardiographic parameter and for body weight. Males and females were considered separately and together. Each parameter was analysed statistically to check for differences between the sexes and for correlations with body weight. A statistically significant difference between the sexes was only observed for LVWT in systole and diastole. A linear regression with body weight was obtained only for LVID in systole and in diastole. The results show that morphofunctional cardiac homogeneity is independent of size in dogs of this breed and age.

Effect of Increasing Intraabdominal Pressure and Volume on Left Ventricular Function in Continuous Ambulatory Peritoneal Dialysis (CAPD)

To determine the effect of increasing intraabdominal pressure on left ventricular (LV) systolic function in patients undergoing continuous ambulatory peritoneal dialysis (CAPD), we studied 15 patients who had been on CAPD for at least 2 months. The study protocol included measurement of echocardiographic LV internal dimensions in diastole and systole, LV wall thickness and mass, LV ejection time, the mean velocity of circumferential fiber shortening (mean Vcf), heart rate, BP, and intraabdominal pressure. Measurements were obtained at baseline (OL) and following intraperitoneal infusion of 1-L increments of dialysate solution (up to 4 L) in both the recumbent and standing positions. Significant differences in LV systolic function resulting from intraperitoneal infusion of dialysate were confined to the subgroup with increased LV wall thickness (n = 8). In this subgroup, mean Vcf decreased progressively from 0.99 +/- 0.18 circumferences/second at baseline to 0.88 +/- 0.16 circumferences/second at 1 L (P = NS), to 0.86 +/- 0.16 circumferences/second at 2 L (P = NS), to 0.66 +/- 0.18 circumferences/second at 3 L (P less than 0.005), and to 0.60 +/- 0.14 circumferences/second at 4 L (P less than 0.005) in recumbent position. Measurements obtained in the standing position paralleled those observed during recumbency. These changes were accompanied by a significant decrease in the mean LV internal dimension in diastole and a significant increase in intraabdominal pressure, but no significant change in the mean LV internal dimensions in systole, mean heart rate, or mean systolic or diastolic BP.(ABSTRACT TRUNCATED AT 250 WORDS)