Changes In Cardiac Parameters Research Articles

Red meat consumption and cardiovascular target organ damage (from the Strong Heart Study).

The aim of this study was to investigate whether red meat consumption is related to changes in left ventricular mass (LVM), left atrial diameter and carotid atherosclerosis in American Indians. We prospectively analyzed echocardiographic and carotid ultrasound data of 1090 adults aged 40 years and older enrolled in the Strong Heart Family Study who were free of cardiovascular disease at baseline - 535 (49%) were hypertensive and 555 (51%) participants were nonhypertensive. Processed and unprocessed red meat intake was ascertained by using a Block food-frequency questionnaire at baseline. Cardiac and vascular biomarkers were assessed at baseline and 4 years later. Marginal models with multivariate adjustment were used to assess the associations of red meat intake with LVM, left atrial diameter, intima-media thickness and presence and extent of carotid atherosclerosis. Participants with hypertension were older, had a higher BMI, were more likely to be diabetic and less physically active. Processed and unprocessed red meat consumption was related to an increase in the presence of atherosclerotic plaques in male and female hypertensive individuals. In male hypertensive participants, processed meat intake was further observed to be associated with an increase in intima-media thickness, atrial diameter but not LVM. In nonhypertensive participants, neither unprocessed nor processed red meat intake was associated with changes in cardiac parameters or carotid atherosclerosis. Over a 4-year period, red meat consumption was related to cardiovascular target organ damage in hypertensive American Indians. These findings emphasize the importance of dietary measures for cardiovascular disease prevention.

Beat-to-beat cardiovascular hemodynamic parameters based on wavelet spectrogram of impedance data

Abstract Impedance cardiography (ICG) is an attractive non-invasive tool for determining cardiac output, systemic vascular resistance and stroke volume (SV). New methods of improving the signal to noise ratio and data processing can infuse new life into this technique. In the present paper, wavelet transform is used to find solutions to two interrelated problems: (1) filtering of tetrapolar thoracic rheography signals (ICG, electrocardiogram and phonocardiogram (PCG)) to suppress random noise and respiratory variation; (2) quantitative description of the ICG and PCG parameters based on the analysis of two-dimensional time-frequency distributions of wavelet coefficients. The wavelet images provide an illustrative representation of the results obtained and allow us to define the ejection time and to control beat-to-beat changes in cardiac parameters in the systolic and diastolic phases of the cardiac cycle. The advantage of the wavelet-based approach is demonstrated by an example of determining the SV variation during the respiratory cycle. Wavelet-based processing of impedance cardiography signals reduces the influence of artifacts and the interference of breathing modulation, and displays the morphological features of cardiac cycles.

Segmentation of anatomical structures of the heart based on echocardiography

Nowadays, many practical applications in the field of medical image processing require valid and reliable segmentation of images in the capacity of input data. Some of the commonly used imaging techniques are ultrasound, CT, and MRI. However, the main difference between the other medical imaging equipment and EchoCG is that it is safer, low cost, non-invasive and non-traumatic. Three-dimensional EchoCG is a non-invasive imaging modality that is complementary and supplementary to two-dimensional imaging and can be used to examine the cardiovascular function and anatomy in different medical settings. The challenging problems, presented by EchoCG image processing, such as speckle phenomena, noise, temporary non-stationarity of processes, unsharp boundaries, attenuation, etc. forced us to consider and compare existing methods and then to develop an innovative approach that can tackle the problems connected with clinical applications. Actual studies are related to the analysis and development of a cardiac parameters automatic detection system by EchoCG that will provide new data on the dynamics of changes in cardiac parameters and improve the accuracy and reliability of the diagnosis. Research study in image segmentation has highlighted the capabilities of image-based methods for medical applications. The focus of the research is both theoretical and practical aspects of the application of the methods. Some of the segmentation approaches can be interesting for the imaging and medical community. Performance evaluation is carried out by comparing the borders, obtained from the considered methods to those manually prescribed by a medical specialist. Promising results demonstrate the possibilities and the limitations of each technique for image segmentation problems. The developed approach allows: to eliminate errors in calculating the geometric parameters of the heart; perform the necessary conditions, such as speed, accuracy, reliability; build a master model that will be an indispensable assistant for operations on a beating heart.

Ramp Study Hemodynamics, Functional Capacity, and Outcome in Heart Failure Patients with Continuous-Flow Left Ventricular Assist Devices.

Ramp studies-measuring changes in cardiac parameters as a function of serial pump speed changes (revolutions per minute [rpm])-are increasingly used to evaluate function and malfunction of continuous-flow left ventricular assist devices (CF-LVADs). We hypothesized that ramp studies can predict functional capacity, quality of life (QOL), and survival in CF-LVAD patients. Hemodynamic changes per Δrpm were measured at a minimum of CF-LVAD support, at baseline pump speed, and at maximal tolerable pump speed. Subsequently functional capacity and QOL were assessed. Eighty ramp tests were performed in 44 patients (HeartMate II, Thoratec Corporation, Pleasanton, CA). Functional status was evaluated in 70% (31/44); average 6 minute walk test (6MWT) was 312 ± 220 min, New York Heart Association (NYHA) I-II/III-IV (70/30%) and activity scores very low-low/moderate-very high (55/45%). Decrease in pulmonary capillary wedge pressure per Δrpm was related to better NYHA classification; NYHA I-II vs. III-IV, -0.29 ± 0.15 vs. -0.09 ± 0.16 mm Hg/rpm * 10 (p = 0.007) as well as to activity score; very low-low vs. moderate-very high, -0.16 ± 0.16 vs. -0.31 ± 0.16 mm Hg/rpm * 10 (p = 0.02). Cardiac output change per Δrpm was correlated to measures of QOL. Ramp tests did not predict survival. In conclusion, hemodynamic changes during ramp studies are associated with measures of functional capacity and QOL. Hence, such tests could potentially identify patients in risk of failure to thrive during CF-LVAD support.

Improved Left Ventricular Structure and Function After Successful Kidney Transplantation

Background/Aims: Cardiac changes observed in chronic kidney disease patients are of multifactorial origin including chronic uremia, hemodynamics or inflammation. Restoration of renal function by kidney transplantation (KTX) may reverse cardiac changes. Novel echocardiographic methods such as speckle tracking echocardiography (STE) allow early and sensitive detection of subtle changes of cardiac parameters. We evaluated changes of cardiac structure and function after KTX by advanced echocardiographic modalities. Methods: Thirty-one KTX recipients (female n=11) were evaluated by medical examination, laboratory testing and echocardiography before and after KTX (median follow-up 19 months). Left ventricular (LV) and right ventricular (RV) diameters and function were assessed by echocardiographic standard parameters. Longitudinal 2D strain of the LV (GLPS) and left atrium (LA) was determined by 2D STE. Results: After KTX, median serum creatinine level was 1.3 mg/dl (IQR, 1.2-1.5). Systolic blood pressure decreased significantly after KTX. Echocardiography showed a significant reduction in LV end-diastolic septal and posterior wall thickness and LV mass index after KTX, which was accompanied by an improvement of GLPS. There were no relevant changes in parameters of LA (reservoir, conduit or contractile) function, LV diastolic or RV function after KTX. Conclusion: LV hypertrophy reversed after successful KTX and was accompanied by an improvement in longitudinal LV function as assessed by STE. Diastolic function and STE-derived LA function parameters did not change significantly after KTX.

Abstract 9950: Patients With Depressive Symptoms Experienced Substantial Adverse Cardiac Remodeling After Myocardial Infarction

Background: Mechanisms underlying post-MI depression and cardiac events in CAD patients remain poorly understood. The OMEGA-REMODEL Study is a randomized double-blind trial assessing for any benefical effects of post-MI LV remodeling by high-dose Omega-3 fatty acids (n-3 FAs). As a post-hoc analysis, we tested the hypothesis that patients with higher depression scores experienced more severe adverse post-MI remodeling. Methods: 358 patients with acute MI were randomized to placebo or 4g/d n-3 FAs with 2-4 weeks post-MI. All patients underwent Hamilton Depression Scale, cardiac MRI, inflammatory biomarkers, and red cell n-3 index at baseline and after 6 months of study drug. Patients were stratified by median depression score as DEP and non-DEP. Results: Demographics and baseline LV measurements are shown in Table 1. N-3 FAs assignment resulted in significant improvement in LVESV compared to placebo. Compared to patients without DEP at baseline, those with DEP had slightly smaller LVEDV but similar LVESV, LVEF and infarct size. However, patients with DEP experienced marked expansion of LVEDV and LVESV compared to patients without DEP during the 6 months study period (P=0.007 and 0.02, respectively). N-3 FAs appeared to benefit LV remodeling of patients with or without DEP. Inflammatory markers did not correlate with the severity of the adverse LV remodeling. Conclusion: In conclusion, patients with DEP were substantially more likely to experience adverse cardiac remodeling which may account for the adverse cardiac outcomes of post MI depression. Table 1: Baseline Features and Changes in Cardiac Parameters

The Effects of Maternal Position and Habitus on Maternal Cardiovascular Parameters as Measured by Cardiac Magnetic Resonance.

To evaluate left ventricular stroke volume (LVSV) and cardiac output (CO) according to maternal position and habitus throughout pregnancy and postpartum using serial cardiac magnetic resonance imaging (c-MRI). This was a prospective study of normotensive nulliparous women using 1.5-T c-MRI performed in both left lateral decubitus and supine positions during three epochs in pregnancy and at 12 weeks' postpartum. Women were stratified according to prepregnancy body mass indices (BMIs) as normal or overweight/obese and compared for LVSV and CO using repeated measures, mixed-random, and fixed-effects model. Between October 2012 and December 2014, 14 normal-weight (BMI 22.2 ± 1.3) and 9 overweight/obese (BMI 29.1 ± 2.0) women underwent c-MRI. During early pregnancy, position did not alter LVSV or CO for either cohort. Beginning at 26 to 30 weeks and continuing to 32 to 36 weeks, normal-weight women demonstrated significant positional differences for LVSV and CO (both p < 0.01). In contrast, positional differences did not influence these parameters in overweight/obese women. At 12 weeks' postpartum, all influence of position had dissipated for both cohorts. Maternal position has no effect on LVSV or CO during the first half of pregnancy. In the second half, however, only normal-weight women exhibit significant changes in cardiac parameters when comparing the left lateral decubitus with supine position.

The effect of anticoagulant therapy on coagulation and inflammation markers in sepsis patients and its significance

To study the effect of anticoagulant therapy with low molecular weight heparin (LMWH) on coagulation and inflammation markers in sepsis patients. A prospective randomized controlled trial ( RCT ) was conducted. Eighty-seven patients suffering from septic shock undergoing mechanical ventilation in Department of Critical Care Medicine of Subei People's Hospital from June 2012 to September 2014 were enrolled. The hemodynamic changes before and after PLR were monitored by pulse indicated continuous cardiac output ( PiCCO ) and PVI monitoring. Responsive group: positive fluid response was defined as an increase in cardiac index ( CI )≥10% after PLR. Unresponsive group: negative fluid response was defined as an increase in CI<10% after PLR. The hemodynamic parameters, including heart rate ( HR ), mean arterial pressure ( MAP ), central venous pressure ( CVP ), stroke volume variation ( SVV ), CI and PVI, and the changes in cardiac parameters (ΔHR, ΔMAP, ΔCVP, ΔSVV, ΔCI, and ΔPVI ) before and after PLR were determined. The relations between hemodynamic parameters and their changes with ΔCI were analyzed by the Pearson analysis. The role of the parameters for volume responsiveness prediction was evaluated by receiver operating characteristic ( ROC ) curves. There were no significant differences in values of all parameters, including CD62p, D-dimmer, IL-6, TNF-α, and APACHE II score at 1 day of treatment. The values of all parameters in observation group were gradually decreased. CD62p at 3 days of treatment and D-dimmer, IL-6, TNF-α, and APACHE II score at 5 days of treatment were significantly lower than those at 1 day of treatment. The values in the control group were decreased at first and then increased, as D-dimmer, IL-6 and TNF-α were significantly higher on the 5th day than those at 1 day of treatment. Compared with control group, CD62p, D-dimmer, IL-6, TNF-α and APACHE II score on the 7th day of treatment were significantly lowered in observation group [CD62 (μg/L): 22.64±2.88 vs. 31.52±2.81, D-dimmer (g/L): 1.32±0.46 vs. 4.79±0.82, IL-6 (ng/L): 5.84±1.87 vs. 49.64±3.12, TNF-α (ng/L): 21.04±3.15 vs. 130.58±6.26, APACHE II score: 9.71±2.02 vs. 14.17±2.38, all P < 0.05]. Correlation analysis showed that in observation group, CD62p, D-dimmer, IL-6, and TNF-α were positively correlated with APACHE II score (r value was 0.907, 0.868, 0.880, 0.693, respectively, all P=0.000). The incidence of MODS in observation group was significantly lower than that in the control group [26.7% (8/30) vs. 46.7% (14/30), χ (2)=3.943, P = 0.028]. LMWH, which was given early in sepsis, can significantly down-regulate the expression of CD62p, D-dimmer, IL-6 and TNF-α, and reduce the incidence of MODS. Some indicators regarding coagulation and inflammation can be used as supplementary indicators to severity scores, and it may be able to improve the accuracy of scoring systems for sepsis.

A prospective clinical study of pleth variability index in prediction of volume responsiveness in patients with septic shock

To evaluate the role of pleth variability index ( PVI ) by passive leg raising ( PLR ) test in volume responsiveness and volume status prediction in patients with septic shock. A prospective randomized controlled trial ( RCT ) was conducted. Eighty-seven patients suffering from septic shock undergoing mechanical ventilation in Department of Critical Care Medicine of Subei People's Hospital from June 2012 to September 2014 were enrolled. The hemodynamic changes before and after PLR were monitored by pulse indicated continuous cardiac output ( PiCCO ) and PVI monitoring. Responsive group: positive fluid response was defined as an increase in cardiac index ( CI )≥10% after PLR. Unresponsive group: negative fluid response was defined as an increase in CI<10% after PLR. The hemodynamic parameters, including heart rate ( HR ), mean arterial pressure ( MAP ), central venous pressure ( CVP ), stroke volume variation ( SVV ), CI and PVI, and the changes in cardiac parameters (ΔHR, ΔMAP, ΔCVP, ΔSVV, ΔCI, and ΔPVI ) before and after PLR were determined. The relations between hemodynamic parameters and their changes with ΔCI were analyzed by the Pearson analysis. The role of the parameters for volume responsiveness prediction was evaluated by receiver operating characteristic ( ROC ) curves. 145 PLRs in 87 patients with septic shock were conducted, with 67 in responsive group and 78 in unresponsive group. There were no statistically significant differences in HR, MAP, CVP and CI before PLR between the responsive and unresponsive groups. SVV and PVI in responsive group were significantly higher than those in the unresponsive group [ SVV: ( 16.9±3.1 )% vs. ( 8.4±2.2 ) %, t = 9.078, P = 0.031; PVI: ( 20.6±4.3 )% vs. ( 11.1±3.2 )%, t = 19.189, P = 0.022 ]. There were no statistically significant differences in HR, MAP, CVP, SVV, and PVI after PLR between the responsive group and unresponsive group. CI in the responsive group was significantly higher than that in the unresponsive group ( mL×s(-1)×m(-2): 78.3±6.7 vs. 60.0±8.3, t = 2.902, P = 0.025 ). There were no statistically significant differences in ΔHR, ΔMAP, ΔCVP between responsive group and unresponsive group. ΔSVV, ΔCI and ΔPVI in responsive group were significantly higher than those in the unresponsive group [ ΔSVV: ( 4.6±1.5 )% vs. ( 1.8±0.9 )%, t = 11.187, P = 0.022; ΔCI ( mL×s(-1)×m(-2) ): 18.3±1.7 vs. 1.7±0.5, t = 3.696, P = 0.014; ΔPVI: ( 6.4±1.1 )% vs. ( 1.3±0.2 )%, t = 19.563, P = 0.013 ]. No significant correlation between HR, MAP or CVP before PLR and ΔCI was found. SVV ( r = 0.850, P = 0.015 ) and PVI ( r = 0.867, P = 0.001 ) before PLR were correlated with ΔCI. It was shown by ROC curve that the area under ROC curve ( AUC ) for SVV fluid responsiveness prediction was 0.948, and cut-off of SVV was 12.4%, the sensitivity was 85.4%, and specificity was 86.6%. The AUC for PVI fluid responsiveness prediction was 0.957, and cut-off was 14.8%, the sensitivity was 87.5%, and specificity was 84.8%. It was higher than other hemodynamic parameters ( HR, MAP, CVP ). PVI and SVV can better predict fluid responsiveness in mechanically ventilating patients with septic shock after PLR. PVI as a new continuous, noninvasive and functional hemodynamic parameter has the same accuracy as SVV.

Effects of exercise training on the hemodynamics in patients with chronic heart failure

Background and purpose: It is still unclear physiological mechanisms of preserved exercise-tolerance in patients with stable chronic heart failure, irrespective decreased left ventricular ejection fraction. We tried to investigate underlying mechanisms. Methods: Consecutive 62 patients with stable chronic heart failure under oral medications were enrolled (NYHA II-III). Exercise test was performed on a symptomlimited bicycle ergometer. We analyzed changes in cardiac parameters by means of non-invasive whole body electrical bio-impedance using NICaS apparatus during exercise. Age (yrs, 25%-75% range): 63 (49-72). Ejection Fraction (%): 61 (38- 69). Basic diseases of heart failure: Idiopathic dilated cardiomyopathy 22; Valvular heart disease 22; Old myocardial infarction 15; Congenital heart disease 2; Hypertensive heart disease 1. Results: Comparing before and after exercise, heart rate was significantly increased after exercise, but there were no significant changes in mean blood pressure. While total peripheral vascular resistance index tended to be decreased, cardiac index tended to be increased. Conclusions: There might exist beneficial physiological mechanisms to decrease total peripheral vascular resistance accompanied with increasing cardiac output during exercise in patients with stable chronic heart failure associated with preserved exercise-tolerance. Exercise-induced peripheral vasodilation may underlie

Термодинамический и хаотический подходы в оценке возрастной динамики сердечно-сосудистой системы женщин-ханты

Cardiorespiratory system is the most important part of the body, which provides high life expectancy. Special parameters of heart rate dynamics require the development of new approaches for analysis and prediction. The paper presents a comparison of the effective traditional statistical methods, the conventional (in physics) thermodynamic methods, with methods of chaos theory and self-organization to estimate the parameters of heart rate three age groups of Khanty-women in the aspect of identification of their age characteristics. It is proved that there are few statistical differences between the groups (one-type uncertainty), entropic parameters are also less informative. On the contrary, the quasi-attractor’s parameters in three age groups of women are purposefully changed (decrease) and can be described by the Verhulst-Pearl model, with the calculation of the rate of changes over time. A new method for estimating the age-related changes of cardiac parameters based in the calculation of rate of change of the quasi-attractor’s volume is proposed.

Dipeptidyl peptidase-4 inhibitors are associated with improved left ventricular diastolic function after acute myocardial infarction in diabetic patients.

Dipeptidyl peptidase-4 (DPP4) is an integral membrane glycoprotein that modulates the pathological state of diabetes mellitus (DM), and DPP4 inhibitors are a new class of anti-type-2 DM drugs. Recent preclinical studies have associated DPP4 inhibition with improved myocardial systolic and diastolic function. Based on preclinical findings, we investigated associations between the administration of DPP4 inhibitors and cardiac function after acute myocardial infarction (AMI) in a clinical setting. We enrolled 34 patients with diabetes who were treated for acute myocardial infarction at our hospital between January 2010 and December 2012. We retrospectively compared changes in cardiac parameters determined by trans-thoracic echocardiography between patients treated with (DPP4-I group; n=13) or without (non-DPP4-I group; n=21) a DPP4 inhibitor during follow-up. The values of E/e' and of e'/a' significantly decreased and increased, respectively, in the DPP4-I, compared with the non-DPP4-I group (-2.53±5.53 vs. 2.58±5.68, p=0.038 and 0.08±0.23 vs. -0.12±0.21, p=0.036, respectively). We concluded that DPP4 inhibitors could improve E/e' and e'/a' in patients with DM and AMI and thus might be effective for treating left ventricular diastolic failure.

Cardiac responses to selected cranial osteopathic manipulations in healthy young men (LB656)

Background and Purpose: Cranial manipulations (CM) as a part of osteopathic manipulative treatment have been used to treat patients. However, physiological responses to CM are not well defined in literature. The purpose of this study was to measure changes in heart rate (HR), heart rate variability (HRV), stroke volume index (SI), and cardiac index (CI) in response to selected CM and sham manipulation.Method: Healthy 25‐35 year old men participated in this study. Non‐invasive impedance cardiography method was used to measure changes in cardiac parameters before and after manipulations. Data were recorded and analyzed using BIOPAC Systems, Inc. equipment and software. All manipulations were performed by the same osteopathic physician.Results: CM increased parasympathetic input (70%) to the heart resulting in decreased HR (5%) and CI (7%) without significant effect on SI. These changes were not seen in sham manipulation.Conclusion: Selected CM decreased CI by decreasing HR without significant effect on cardiac contractility in healthy young men. Future studies will compare gender and age differences in response to osteopathic techniques.Grant Funding Source: This project was funded by the TUN Research Grant Award

Detection of subclinical anthracycline induced cardiotoxicity in breast cancer survivors

Aims : To assess the chronic cardiac effects of anthracycline-based chemotherapy regimens on atrial and ventricular diameter, ejection fraction, and valvular abnormalities in relation to cumulative dose in breast cancer patients. Materials and Methods: Breast cancer patients who had received anthracycline-based chemotherapy and radiation therapy were enrolled. All patients had undergone a baseline and follow-up electrocardiogrphy, echocardiography, and clinical cardiac evaluation. Any changes in cardiac parameters were noted. Statistical Analysis Used: Statistical measures used were Chi-square test and independent t-test. Results: A total of 75 breast cancer patients were assessed. Out of these, 56 patients who received cumulative dose of doxorubicin ≥300 mg/m 2 showed increased cardiac dysfunction. Patients with left side breast cancer had greater cardiac abnormalities compared with right side. Conclusion: Cardiac dysfunction was significant with cumulative dose of doxorubicin ≥300 mg/m 2 and also was observed more in left side breast cancer patients.

Normative annual changes in left ventricular volumes, mass and function among healthy adults: a prospective cardiac magnetic resonance imaging study

Background Cardiac magnetic resonance imaging (CMR) is routinely performed to monitor progression and response to interventions in congenital and acquired heart diseases. Cross-sectional CMR studies report normalized reference ranges for cardiac parameters according to age decile together with assessments of short-term inter-study variability; however, most clinical imaging is repeated at much greater intervals of time. There are no prospective CMR data defining long-term changes in cardiac structure and function among healthy subjects. Without such data, it is difficult to determine whether serial changes in cardiac parameters observed in patients reflect disease progression or are merely the consequence of normal ageing. We examined the “within patient” changes in left ventricular (LV) volumes, mass and function over 12 months in a well-characterized cohort of healthy adults. Methods We identified 21 healthy controls (age 39 ± 13 yr, male 71%) who did not proceed to uni-nephrectomy after recruitment into an observational study assessing the cardiovascular effects of live kidney donation (NCT01028703). All subjects were asymptomatic and had a 10-year risk of a cardiovascular event of <20% (QRISK-2), a normal stress echocardiogram and normal haematology and biochemistry profiles. Exclusion criteria included: any history of cardiovascular disease, including hypertension; diabetes; glucose intolerance; chronic kidney disease; first degree relative with a proven or potentially inheritable cardiac condition. Subjects underwent CMR imaging (1.5T Magnetom Avanto, Siemens) at baseline and 12 months. Analysis of SSFP images was performed offline (Argus Software, Siemens) by a single blinded observer (W.E.M.) for assessment of LV volumes, systolic function and mass. Baseline studies were repeat analyzed by the same trained observer to assess intra-observer variability. A subset of participants underwent repeat imaging within 1 hour to determine inter-study variability. Results

The effect of topical ophthalmic 1% atropine on heart rate and rhythm in normal dogs

To determine if topically administered ophthalmic atropine affects heart rate or rhythm in clinically normal dogs. Two groups of 15 healthy dogs were evaluated, one consisting of dogs weighing <15 kg, the other consisting of dogs weighing >15 kg. Each dog was suited with a Holter monitor. At start time 0, dogs received one drop of ophthalmic 1% atropine solution, or one drop of sterile saline solution as a control in each eye, via random assignment. Each dog served as their own control. This procedure was repeated two more times, at 6-h intervals, for a total of three treatments over a 12-h period. Holter monitors recorded heart rate and rhythm for 24 h. Statistical analysis was performed to compare values between the groups. Dose dependent changes in cardiac parameters were evaluated. The mean heart rate and average minimum heart rate was significantly higher during the treatment period compared to the control period (8% and 13%, respectively). The mean number of hours with a heart rate <50 bpm decreased by 47% in the treatment vs. the control period. The mean maximum heart rate and number of h with a heart rate > 180 bpm did not differ significantly between the two groups. There was no evidence of dose dependence on heart rate when comparing small and large dogs. No significant differences in heart rhythm were noted between groups for measurable parameters. Topically administered atropine causes a small but significant increase in heart rate in healthy dogs.

Adverse Impact of Diet-Induced Hypercholesterolemia on Cardiovascular Tissue Homeostasis in a Rabbit Model: Time-Dependent Changes in Cardiac Parameters

The present study evaluates a hypothesis that diet-related hypercholesterolemia increases oxidative stress-related burden to cardiovascular tissue, resulting in progressively increased mortality, along with deterioration of electrophysiological and enzymatic function in rabbit myocardium. New Zealand white rabbits were divided into four groups, defined as follows: GROUP I, cholesterol-free rabbit chow for 12 weeks; GROUP II, cholesterol-free chow, 40 weeks; GROUP III, chow supplemented with 2% cholesterol, 12 weeks; GROUP IV, chow supplemented with 2% cholesterol, 40 weeks. At the 12 and 40 weeks time points, animals in each of the aforementioned cohorts were subjected to echocardiographic measurements, followed by sacrifice. Significant deterioration in major outcome variables measured in the present study were observed only in animals maintained for 40 weeks on 2% cholesterol-supplemented chow, with much lesser adverse effects noted in animals fed high cholesterol diets for only 12 weeks. It was observed that rabbits receiving high cholesterol diets for 40 weeks exhibited significantly increased mortality, worsened ejection fraction and general deterioration of cardiac functions, along with increased atherosclerotic plaque formation and infarct size. Additionally, myocardium of GROUP IV animals was observed to contain lower levels of heme oxygenase-1 (HO-1) and cytochrome c oxidase III (COX III) protein relative to the controls.

Recovery of Heart Rate Variability and Ventricular Repolarization Indices Following Exercise

There is a heightened risk of sudden cardiac death related to exercise and the postexercise recovery period, but the precise mechanism is unknown. We have demonstrated that sympathoexcitation persists for ≥45 minutes after exercise in normals and subjects with coronary artery disease (CAD). The purpose of this study is to determine whether this persistent sympathoexcitation is associated with persistent heart rate variability (HRV) and ventricular repolarization changes in the postexercise recovery period. Twenty control subjects (age 50.7 ± 1.4 years), 68 subjects (age 58.2 ± 1.5 years) with CAD and preserved left ventricular ejection fraction (LVEF), and 18 subjects (age 57.6 ± 2.4 years) with CAD and depressed LVEF underwent a 16-minute submaximal bicycle exercise protocol with continuous ECG monitoring. QT and RR intervals were measured in recovery to calculate the time dependent corrected QT intervals (QTc), the QT-RR relationship, and HRV. QTc was dependent on the choice of rate correction formula. There were no differences in QT-RR slopes among the three groups in early recovery. HRV recovered quickly in controls, more slowly in those with CAD-preserved LVEF, and to a lesser extent in those with CAD-depressed LVEF. Despite persistent sympathoexcitation for the 45-minute recovery period, ventricular repolarization changes do not persist for that long and HRV changes differ by group. Additional understanding of the dynamic changes in cardiac parameters after exercise is needed to explore the mechanism of increased sudden cardiac death risk at this time.

RESPOSTAS ELETROCARDIOGRÁFICAS DE EQUINOS AO TREINAMENTO COM BASE NA CURVA VELOCIDADE-LACTATO DETERMINADA EM ESTEIRA ROLANTE

The aim of this study was to evaluate, by electrocardiographic analysis, equine cardiovascular adaptations to training based on speed-lactate curve. For this evaluation, eight Arabian horses previously submitted to four months of rest were used. The animals performed a graded exercise test (ET) and samples were collected for blood lactate measurement. The speed where the blood lactate concentration reached 4.0 mmol / L (V4) was calculated by regression analysis. The estimated training speed was 60% of V4 performed on a treadmill for 45 min three times a week on alternate days for eight weeks. The electrocardiogram (ECG) analysis was made before and after the beginning of the training. The training improvement is confirmed by the increase in both V2 and V4 of the second ET. After the second ECG analysis, a significant increase in the R wave amplitude was observed. Training improved the metabolic activity, promoted discrete changes in electrocardiogram; however, it was not adequate to result changes in cardiac parameters. KEYWORDS: Training adaptation, cardiovascular, electrocardiogram, treadmill, equine.

The effect of Glucagon-Like Peptide-2 on mesenteric blood flow and cardiac parameters in end-jejunostomy short bowel patients

Background Exogenous Glucagon-Like Peptide-2 (GLP-2) treatment improves intestinal wet weight absorption in short bowel syndrome (SBS) patients. In healthy subjects, administration of GLP-2 increases small intestinal blood flow. The aim of the study was to evaluate the effect of GLP-2 on mesenteric blood flow and dynamic changes in cardiac parameters in SBS patients with jejunostomy and varying length of remnant small intestine. Methods 8 SBS patients with end-jejunostomy and less than 200 cm small intestine were given GLP-2, 1600 μg subcutaneously (SC), or isotonic saline in a double blinded manner. At 0, 30 and 60 min plasma GLP-2 was measured, and from 0 to 90 min, blood flow in the superior mesenteric artery (SMA) and the celiac artery (CA) was measured using Doppler ultrasound (US), and cardiovascular variables were measured by continuous impedance cardiography and finger plethysmography. Results Plasma GLP-2 concentrations increased significantly in the GLP-2 group, whereas no changes were seen in the placebo group. Compared to baseline, GLP-2 SC elicited a 19.4% decrease (p < 0.01) in the resistance index (RI) and a 97.6% increase in time averaged maximal velocity (TAMV) in the SMA (P < 0.01). In the CA there were no significant changes in RI or TAMV in the GLP-2 or placebo group. Blood flow and length of remaining intestine were correlated (RI: y = 0.14 + 4.3, R = 0.83, p = 0.01 and TAMV: y = 1.21 + 21.3, R = 0.63, p = 0.09). GLP-2 non significantly increased cardiac output (CO), stroke volume (SV) and significantly increased heart rate (HR) compared to baseline. Conclusion Subcutaneous GLP-2 increased SMA blood flow in end-jejunostomy SBS patients with less than 200 cm of remaining small intestine. The increase in blood flow correlated with the length of remaining intestine, suggesting that the increase is coupled to the metabolic actions of GLP-2 on the gut rather than effects on the vasculature.