Ventricular Ejection Rate Research Articles

Effects of post-treatment electroacupuncture on ventricular monophasic action potential and cardiac function in a rat model of ischemia/reperfusion injury.

To determine the effects of post-treatment electroacupuncture (EA) on the electrophysiological properties of ventricular muscle in rats with ischemia/reperfusion (IR) injury. Male Sprague-Dawley (SD) rats were randomly assigned into sham-operated (SH), IR and IR + EA groups (n = 8 each). The IR model was generated by ligation of the left anterior descending (LAD) coronary artery for 30 min. After establishing the IR model, EA was administered at PC6 for 30 min while opening the coronary artery and allowing reperfusion for 30 min. Heart rate (HR), mean arterial pressure and monophasic action potential (MAP) of cardiac muscle in the outer membrane of the antetheca of the left ventricle before coronary artery ligation (T0), after coronary artery ligation for 30 min (T1) and after reperfusion for 30 min (T2) were recorded. At the same time, ventricular electrophysiological parameters including ventricular effective refractory period (ERP), conduction velocity (CV) and ventricular fibrillation threshold (VFT) were measured. Then, the cardiac function and the levels of creatine kinase-muscle/brain (CK-MB) and cardiac troponin I (cTnI) were monitored. Based on these data, monophasic action potential amplitude (MAPA), the maximum depolarization velocity (Vmax) and the MAP durations at 50% and 90% repolarization (MAPD50 and MAPD90) were calculated to determine the incidence of arrhythmia during reperfusion. Compared with the SH group, the IR group showed an obviously decreased HR as well as reduced mean arterial pressure, Vmax, CV, ERP and MAPA. All indices of cardiac function except left ventricular end-diastolic pressure (LVEDP) decreased (i.e. ventricular systolic pressure (LVSP), left ventricular ejection fraction (LVEF), fractional shortening (FS) and rate of the ventricular pressure rise/drop (±dp/dt)). Furthermore, the MAPD50 and MAPD90 were prolonged, and the levels of CK-MB and cTnI increased (p < 0.05). In comparison to the IR group, HR and the mean arterial pressure were increased. All indices of cardiac function except LVEDP increased (LVSP, LVEF, FS and ±dp/dt). Vmax, CV, ERP and MAPA were also increased in the IR + EA group. However, MAPD50 and MAPD90 were distinctly shortened, and the levels of CK-MB and cTnI decreased (p < 0.05). There were no statistically significant differences in VFT between the three groups (p > 0.05). EA post-treatment can relieve prolongation of repolarization and slowed depolarization of ventricular muscle during IR, thus decreasing the rate of incidence of reperfusion arrhythmia.

Combination of Linagliptin and Empagliflozin Preserves Cardiac Systolic Function in an Ischemia-Reperfusion Injury Mice With Diabetes Mellitus.

BackgroundSodium-glucose co-transporter 2 inhibitor (SGLT2i) and dipeptidyl peptidase 4 inhibitor (DPP4i) are oral hypoglycemic agents. Although SGLT2i has been shown having the beneficial effects on heart failure in basic and clinical studies, the combined effects of SGLT2i and DPP4i have not been established well. We investigated the effects of SGLT2i and DPP4i against diabetes mice model of myocardial ischemia-reperfusion injury.MethodsStreptozotocin-induced diabetic C57BL/6J mice were divided into control (vehicle), empagliflozin (30 mg/kg/day), linagliptin (3 mg/kg/day) and combination (30 mg/kg/day and 3 mg/kg/day, respectively) groups. After 7 days of drug administration, 30 min of myocardial ischemia was performed. We investigated body weight, heart weight, blood glucose, and cardiac functions by pressure-volume Millar catheter followed by 28 days of additional drug administration.ResultsBlood glucose levels, body weight, and heart weight were not significantly different between the groups. In Millar catheter analysis, left ventricular volume at the peak left ventricular ejection rate which is one of the cardiac systolic parameters in combination group was significantly preserved than that in control (P = 0.036). The cardiac index in the combination group tended to be preserved compared to that in the control (P = 0.06). The pathological fibrotic area in the left ventricle in the combination group also tended to be smaller (P = 0.08).ConclusionsCombination therapy with linagliptin and empagliflozin preserved cardiac systolic function on the diabetes mice model of myocardial ischemia-reperfusion injury independent of blood glucose levels.

INTEGRATED EFFECTS OF NORMOBARIC HYPOXIA AND METABOREFLEX ACTIVATION ON HEMODYNAMICS

IntroductionBoth metaboreflex activity and hypoxia affect hemodynamics. In particular, metaboreflex induces an augmentation in stroke volume (SV), systemic vascular resistance (SVR), and blood pressure (BP) by activating the sympathetic nervous system (SNS). In contrast, hypoxia produces a heart rate (HR)‐mediated increase in cardiac output (CO), while its effect on SVR is variable as it increases SNS activity but, at the same time, it triggers nitric oxide (NO) production in the endothelium, thus inducing venous and arteriolar dilation. Since studies on the possible interaction between metaboreflex and hypoxia are still lacking, our investigation aimed to study their combined effects on hemodynamics.Methods11 male subjects underwent a preliminary cardiopulmonary exercise test (CPET) on a cycle ergometer to assess their aerobic fitness. Then, a metaboreflex activation protocol in normoxia and normobaric hypoxia (fraction of inspired oxygen – FiO2 – of 13.5%) was conducted on separate days. Hypoxia was induced using a hypoxic gas generator (Everest Summit II Generator, Hypoxico, USA) connected to the subjects by a facemask. The metaboreflex activation protocol consisted of two randomly assigned sessions: one of post‐exercise muscle ischemia (PEMI) and one of control exercise recovery (CER). PEMI comprised a 3‐minute exercise bout pedaling at 30% of the maximum workload reached during the CPET followed by 3 minutes of vascular occlusion using an inflatable thigh cuff to stimulate the metaboreflex. CER was similar, but no occlusion was applied after the exercise session. SV, HR, CO, ventricular filling rate (VFR), and ventricular ejection rate (VER) were measured through impedance cardiography while mean blood pressure (MBP) was assessed using manual sphygmomanometer. SVR was calculated indirectly from CO and MBP according to Poiseuille’s law. Near‐infrared spectroscopy was employed to measure cerebral oxygenation (COX) and peripheral hemoglobin saturation (SPO2) to control the level of tissue hypoxia. Two‐way ANOVA and paired sample t‐test were utilized when appropriate.ResultsCO was increased during metaboreflex activation in normoxia (p= 0.013) but not in hypoxia. SV, CO, and VFR responses to metaboreflex (measured as the difference PEMI‐CER at the third minute after exercise) were reduced when the hypoxic stimulus was applied (p=0.02; p=0.02; p=0.003 respectively). Moreover, SVR response showed a nearly significant (p=0.07) increase in hypoxia, with MBP response being unchanged. COX and SPO2 confirmed that the hypoxic stimulus was effective.DiscussionResults demonstrated that hypoxia impaired the hemodynamic response to metaboreflex. Specifically, SV was reduced during metaboreflex in hypoxia because of a reduction in preload as a consequence of two mechanisms: 1) a reduction in venous return probably induced by NO‐mediated vasodilation of the venous bed; 2) an increase in right ventricle afterload likely produced by the pulmonary arterial system vasoconstriction. Of note, baroreflex successfully defended MBP response despite the reduced CO during hypoxia.

Mitral and aortic paravalvular leaks closure: Insights from the prospective international multicenter FFPP cohort study

Percutaneous paravalvular leak closure (PVLc) has emerged as an alternative to surgery. It remains a technically challenging procedure. We aim to compare outcomes after mitral and aortic PVLc. We analyzed data from PVLc procedures performed over the 2 first years of inclusion in the FFPP (Fermeture de Fuite Périprothétique) study, a prospective observational industry-independent cohort study which started in January 2017. We analyzed 147 PVLc (99 mitral–48 aortic), performed in 127 patients (1 procedure in 109 patients, 2 in 16 and 3 in 2) included in 22 centers among 3 countries (France, Poland and Belgium). Age (69 ± 10 versus 69 ± 11 yo), left ventricular ejection fraction (56 versus 51%), Euroscore2 (9 versus 7.6) and rate of mechanical valve (56.7% versus 41.7%, P = 0.1) were not significantly different among mitral and aortic groups. All patients had heart failure and/or hemolytic anemia. Hemolysis was more common in mitral PVL (62 versus 43%, P = 0.04). A mean of 1.4 (min 1, max 3) and 1.8 (min 1 max 5) devices were respectively required for technically successful aortic and mitral PVLc. No complication was reported in procedures with failure of device implantation. Aortic PVLc were faster than mitral PVLc (1h18 versus 2h20), with a trend towards a higher rate of technical success (96% versus 87%, P = 0.1) and fewer rate of major adverse events (worsening hemolysis, stroke, life threatening events and deaths; 2% versus 14%, P = 0.02). At 1 month follow-up, events were reported in 2% of patients (blood transfusion for hemolysis) versus 26.2% (deaths 3.3%; hemolysis 14.8%; heart failure 3.3%; heart failure and hemolysis 4.9%) after successful aortic and mitral PVLc respectively, P = 0.6. Mitral PVLc is a more complex procedure than aortic PVLc, with a lower success rate and a higher risk of peri-procedural and one-month severe adverse events. Longer follow-up data are expected and will be available from this on-going study.

Predictors of Elevated Defibrillation Threshold with the Subcutaneous Implantable Cardioverter-defibrillator.

There are limited data regarding defibrillation thresholds (DFTs) for the subcutaneous implantable cardioverter-defibrillator (S-ICD), and factors associated with elevated DFTs remain incompletely understood. The objective of this study was to determine the factors associated with elevated DFTs in patients undergoing S-ICD implantation. A retrospective cross-sectional analysis of all patients undergoing S-ICD implantation at our institution between 2013 and 2016 who underwent step-down DFT testing was performed. Factors associated with a higher DFT were analyzed. In total, 56 patients (mean age: 49.3 ± 13.1 years, mean left ventricular ejection rate: 31.1% ± 13.7%) underwent S-ICD implantation in the study period. Full DFT testing was performed in 31 of the 56 patients (55%), with an average DFT of 46.4 joules (J) ± 25.9 J found among this cohort. The DFT was > 65 J in five of the 31 patients (16%). A high DFT was associated with increased body mass index (BMI) (37.7 kg/m2 versus 29.4 kg/m2; p = 0.02) and either increased septal or posterior wall thickness (1.5 cm versus 1.0 cm; p = 0.0003 and 1.4 cm versus 1.1 cm; p= 0.003, respectively). Patients with high DFTs also had higher failed shock impedance values (138 Ω versus 71 Ω; p = 0.005). Renal failure did not appear to affect DFT (51.4 J versus 51.7 J; p = 0.99). BMI, body surface area (BSA), and septal and posterior left ventricular wall thickness predicted elevated DFT on univariate analysis, although findings were not significant with multivariate analysis due to the small sample size. Thus, elevated S-ICD DFT appears to be associated with increased BMI, BSA, and septal or posterior wall thickness. In contrast, dialysis-dependent renal failure is not associated with elevated DFT. Further investigation is necessary in order to better characterize and predict which patients are at-risk for high DFTs.

Identifying Hemodynamic Determinants of Pulse Pressure: A Combined Numerical and Physiological Approach.

We examined the ability of a simple reduced model comprising a proximal characteristic impedance linked to a Windkessel element to accurately predict central pulse pressure (PP) from aortic blood flow, verified that parameters of the model corresponded to physical properties, and applied the model to examine PP dependence on cardiac and vascular properties. PP obtained from the reduced model was compared with theoretical values obtained in silico and measured values in vivo. Theoretical values were obtained using a distributed multisegment model in a population of virtual (computed) subjects in which cardiovascular properties were varied over the pathophysiological range. In vivo measurements were in normotensive subjects during modulation of physiology with vasoactive drugs and in hypertensive subjects. Central PP derived from the reduced model agreed with theoretical values (mean difference±SD, -0.09±1.96 mm Hg) and with measured values (mean differences -1.95±3.74 and -1.18±3.67 mm Hg for normotensive and hypertensive subjects, respectively). Parameters extracted from the reduced model agreed closely with theoretical and measured physical properties. Central PP was seen to be determined mainly by total arterial compliance (inversely associated with central arterial stiffness) and ventricular dynamics: the blood volume ejected by the ventricle into the aorta up to time of peak pressure and blood flow into the aorta (corresponding to the rate of ventricular ejection) up to this time point. Increased flow and volume accounted for 20.1 mm Hg (52%) of the 39.0 mm Hg difference in PP between the upper and lower tertiles of the hypertensive subjects.

Wall stress determines systolic and diastolic function — Characteristics of heart failure

IntroductionHeart failure can be caused by systolic or diastolic dysfunction. Diagnosing diastolic dysfunction remains challenging, although several criteria have been identified. Ventricular wall stress is crucially involved. It is hypothesized whether increased end-diastolic and end-systolic ventricular wall stress as assessed by the wall stress index is associated with cardiac dysfunction and thus provide novel diagnostic criteria. Methods1050 consecutive patients with suspected non-ischemic heart failure covering a broad spectrum from normal to severely impaired cardiac function were observed. Cardiac magnetic resonance imaging was performed to assess left ventricular (LV) volumes, myocardial mass, peak ejection (PER) and filling rate (PFR). ResultsA reduced PFR was found in 348 patients (33.1%), which resulted from 275 of 422 patients (65.2%) with reduced and from 73 of 628 patients (11.6%) with preserved LVEF (p<0.0001). Increased LV volume and mass was correlated with reduced PER and PFR (p<0.0001). Increased end-diastolic wall stress was the strongest predictor of a reduced PER (OR 4.5 [2.6 to 7.8], p<0.0001) and increased end-systolic wall stress predicted a reduced PFR (OR 1.2 [1.1 to 1.3], p<0.0001). Increased end-systolic wall stress was correlated with increased pulmonary pressure (p<0.0001). Normal end-systolic wall stress <18kPa had a favorable predictive value for the absence of an impaired filling and increased pulmonary capillary pressure. ConclusionIncreased end-diastolic wall stress precedes a reduced ventricular ejection rate and increased end-systolic wall stress determines an impaired diastolic filling. It is thus suggested to add assessment of ventricular wall stress as diagnostic criterion of heart failure.

CMR EVALUATION OF CARDIAC FUNCTION IN PATIENTS WITH METABOLIC SYNDROME IMPACT ON THE STUDY OF HYPERTENSION

ObjectivesMRI in the evaluation of the metabolic syndrome (metabolic syndrome, MS) on left ventricular function in hypertensive patients in clinical application.Methodsthe Materials and Methods 2.1, the study Collected in March...

한국 성인의 연령에 따른 혈압변화 양상과 고혈압 유병률

A cross-sectional analysis of blood pressure (BP) changes and the current prevalence and distribution of hypertension among age groups in Korea were conducted. Systolic (SBP), diastolic (DBP), and pulse (PP) pressures were evaluated. Residents visiting a local Community Health Center for a health check-up and/or participating in the Health Promotion Program were included for the analyses. A total of 6,570 subjects (2,809 men, 3,761 women) were divided into five age groups: 30-39, 40-49, 50-59, 60-69, and 70≤ years. Comparisons were made between sex and among age groups. SBP and DBP were continuously elevated, while men showed higher levels than women until their mid-60s; then, the trend was reversed. DBP in men became elevated from their 30s, reaching the highest in the 40s then slowly decreasing. DBP in women increased up to their 40s and 50s, then reached a plateau. PP increased rapidly from the 50s in both sexes. The major contributor of age-related BP elevation may be large artery stiffness in men, particularly from their 50s, while the blood pressure elevation of women may relate to diverse factors including large artery stiffness, stroke volume, and ventricular ejection rate. The rapid elevation of PP after the 50s in both men and women could represent a risk of cardiovascular or coronary mortality, particularly with increasing age. The current data showed a higher rate of hypertension in both sexes compared to previous reports. When those with both high-normal BP and hypertension are looked at in combination, BP management of the target population should be drastically elevated.

E0455 Effect on left ventricular function and safety of high maintenance dose of clopidogrel in patients with acute anterior myocardial infarction undergoing selective PCI

ObjectiveTo assess the beneficial efficacy and safety of the high maintenance dose of clopidogrel in acute anterior myocardial infarction (AMI) patients undergoing selective percutaneous coronary intervention (PCI).Methods25 patients were enrolled...

E0633 The effect on Left Ventricular Function and Safety of High Maintenance Dose of Clopidogrel in Patients with Acute Anterior Myocardial Infarction Undergoing Selective PCI

ObjectiveTo assess the beneficial efficacy and safety of the high maintenance dose of clopidogrel in acute anterior myocardial infarction (AMI) patients undergoing selective percutaneous coronary intervention (PCI).MethodsFifty two patients were...

E0637 A compared study of facilitated PCI and primary PCI on acute myocardial infarction via transradial artery approach

ObjectiveTo compare the effects and complications of facilitated PCI and primary PCI in AMI patients for probe the feasibility and safety of the facilitated PCI via transradial artery approach.MethodsTotal of...

E0540 Efficacy and safety of tirofiban-assisted Delayed PCI in Patients with ST-segment elavation myocardial infarction

ObjectiveTo compare the outcomes of IIb/IIIa antagonist assisted PCI within 12–72 h of onset with that of selective PCI within 7–10 days in STEMI patients.MethodsTotally, 80 patients were randomly allocated...

Cardiac Performance During Handgrip Exercise Performed In The Supine And Head-down Tilt Positions

PURPOSE To examine cardiac performance during rhythmic handgrip exercise in the supine versus head-down tilt positions. METHODS Continuous measures of arterial pressure, thoracic bio-impedance, heart sounds, and an electrocardiogram were collected in 12 participants (age:26±2 yr) during 5 minutes of rest (R) and 3 minutes of rhythmic handgrip exercise (HG) performed while lying supine (S) and during 6 degrees of head-down tilt (Dn). Contractions were performed at an intensity of 70% of maximal voluntary contraction and at a rate of 1 contraction per 4 seconds. The following variables were calculated, recorded, and averaged during the last 10 heart beats of each condition: stroke volume (SV), heart rate (HR), mean arterial pressure (MAP), total peripheral resistance (TPR), pre-ejection period (PEP), diastolic time (DT), left ventricular ejection time (LVET), diastolic filling rate (DFR), and left ventricular ejection rate (LVER). A 2 × 2 ANOVA was used to examine differences in the 10-beat average of each variable between conditions. All tests were considered significant at the 0.05 level. RESULTS Data are shown in Table 1. There were main effects of Condition such that MAP, HR, and TPR were greater during HG, and SV, DT, and LVER were lower during HG. Furthermore, there was a main effect of Position such that DT was greater during Dn. Lastly, there was a trend toward a Position × Condition interaction (p =0.07) such that DT was reduced more during Dn-HG compared to S-HG.Table 1: *Main effect of Condition (R vs. HG); † Main effect of Position (S vs. Dn)CONCLUSION HG results in increased MAP, HR, and TPR, and reduced SV, DT, and LVER. Furthermore, these responses appear to be similar in the S and Dn positions, with the possible exception of DT. These data suggest the reduced SV is due to an increased afterload during HG.

Intensified Chop (CHOP14) Plus Rituximab in the Treatment of Elderly Patients with Aggressive and High Risk Non Hodgkin's Lymphoma (NHL).

The results of treatment of aggressive NHL in elderly patients is relatively poor. The use of protocol specifically devised for eldery patients can reduce hematological and extrahematological toxicity but yield worst results, particularly in high-risk IPI patients. Recentely Coiffier et al. have showed that the standard therapy for patients over 60 years with aggressive lymphoma was rituximab plus CHOP. With the aim to improve dose intensity in elderly large cell lymphoma patients and intermediate-high or high-risk IPI score we planned treatment with rituximab 375 mg/sqm on day 0 and CHOP therapy on day +2 given every 2 weeks, with G-CSF starting from day + 7 to + 11 and a profilaxis with cotrimoxazole twice weekly and itraconazole 100 mg day. With an intention to treat analysis we have included in the study, from June 2002 to June 2004, 25 patients with the following characteristics: IPI score 2 in 8 patients (32%), score 3 in 10 (40%) and score 4–5 in 7 (28%). Two patients had diagnosis of follicular grade III lymphoma and the other 23 diffuse large B-cell lymphoma. Eighteen patients (72%) had abnormal value of LDH and 18 patients had one or more extranodal sites involved. The median age was 64 years (60–76), seven patients (28%) were stage II, four (16%) were stage III and fourteen (56%) were stage IV. The aims of the present study were: 1) feasibility 2) toxicity 3) response to therapy. Twenty-two patients completed the estabilished 6 cycles and were evaluable, one patient stopped the treatment after three cycles due to infections the remaining two patients are in treatment. Six patients delayed one cycle and one patient two cycles, due to trombocytopenia or neutropenia. Only eight out 135 cycles were delayed (6%). Sixteen out 23 (70%) patients obtained complete remission (CR) and after a median follow-up of 11 months (1 – 22 months) the disease-free survival was 79%, three patients (19%) relapsed. Two of these patients died rapidly after relapse and one obtained a second CR. Three out 6 patients with a partial response obtained a CR after a salvage therapy, two died and one is still in therapy. With a median follow-up of 15 months (3–25 months) the overall survival was 78%. No remarkable extrahematological toxicity was observed, in particular, as regards cardiotoxicity, we did not observe significant variation of left ventricular ejection rate in comparison with the diagnostic ones, except one patient who, after the sixth cycle, presented a significant reduction of left ventricular ejection which rapidly recovered after he was admitted at hospital. In conclusion we observed that dose intensified CHOP with rituximab was feasible and lack of severe toxicity in elderly patients with aggressive and high risk prognosis lymphoma.

Cardiac Performance During Rhythmic HandgripExercise

2288 PURPOSE:To examine cardiac performance during rhythmic handgrip exercise. METHODS: Continuous measures of arterial pressure, thoracic bio-impedance, heart sounds, and an electrocardiogram were collected in 12 participants (mean age: 26 ± 2 yr) during 5 minutes of supine rest (R), 3 minutes of rhythmic handgrip exercise (EX) and 5 minutes of supine recovery (RC). Contractions were performed at an intensity of 70% of maximal voluntary contraction and at a rate of 1 contraction every 4 seconds. The following variables were recorded and calculated during the last 10 heart beats of each condition: stroke volume (SV), heart rate (HR), cardiac output (Q), mean arterial pressure (MAP), total peripheral resistance (TPR), rate-pressure product (RPP), pre-ejection period (PEP), diastolic time (DT), left ventricular ejection time (LVET), diastolic filling rate (DFR), and left ventricular ejection rate (LVER). A repeated measures ANOVA was used to examine differences in the 10-beat average of each variable between conditions and all tests were considered significant at the 0.05 level. RESULTS: EX resulted in significant increases in MAP (82.7 ± 4 vs .106.5 ± 6 mmHg), TPR (29.2 ± 4 vs. 43.8 ± 9 mmHg·l-1·min-1), HR (58.3 ± 2 vs. 67.7 ± 2 bpm) and RPP (71.7 ± 4 vs. 99.2 ± 7 units) compared to R. EX also resulted in decreases in SV (61.3 ± 7 vs. 53.9 ± 7 ml·beat-1) and LVER (282.7 ± 35 vs. 250.9 ± 34 ml·s-1) compared to R. The aforementioned variables all returned to resting values during RC and did not differ from R. PEP only differed between EX and RC (EX: 239 ± 13; RC: 260 ± 7 ms) and DT was greater during RC (594 ± 35 ms) compared to R (493 ± 19 ms) and EX (447 ± 32 ms). CONCLUSIONS: EX resulted in an increased MAP, TPR, HR and RPP, and a reduced SV and LVER. The reduced SV during EX and it's return to baseline during RC appears to be the result of increases and decreases in afterload, respectively, as DFR was not altered during any condition.

Ethyl pyruvate preserves cardiac function and attenuates oxidative injury after prolonged myocardial ischemia

Objective Myocardial injury and dysfunction following ischemia are mediated in part by reactive oxygen species. Pyruvate, a key glycolytic intermediary, is an effective free radical scavenger but unfortunately is limited by aqueous instability. The ester derivative, ethyl pyruvate, is stable in solution and should function as an antioxidant and energy precursor. This study sought to evaluate ethyl pyruvate as a myocardial protective agent in a rat model of ischemia-reperfusion injury. Methods Rats underwent 30-minute ischemia and 30-minute reperfusion of the left anterior descending coronary artery territory. Immediately prior to both ischemia and reperfusion, animals received an intravenous bolus of either ethyl pyruvate (n = 26) or vehicle control (n = 26). Myocardial high-energy phosphate levels were determined by adenosine triphosphate assay, oxidative injury was measured by lipid peroxidation assay, infarct size was quantified by triphenyltetrazolium chloride staining, and cardiac function was assessed in vivo. Results Ethyl pyruvate administration significantly increased myocardial adenosine triphosphate levels compared with control (87.6 ± 29.2 nmol/g vs 10.0 ± 2.4 nmol/g, P = .03). In ischemic myocardium, ethyl pyruvate reduced oxidative injury compared with control (63.8 ± 3.3 nmol/g vs 89.5 ± 3.0 nmol/g, P < .001). Ethyl pyruvate diminished infarct size as a percentage of area at risk (25.3% ± 1.5% vs 33.6% ± 2.1%, P = .005). Ethyl pyruvate improved myocardial function compared with control (maximum pressure: 86.6 ± 2.9 mm Hg vs 73.5 ± 2.5 mm Hg, P < .001; maximum rate of pressure rise: 3518 ± 243 mm Hg/s vs 2703 ± 175 mm Hg/s, P = .005; maximal rate of ventricular systolic volume ejection: 3097 ± 479 μL/s vs 2120 ± 287 μL/s, P = .04; ejection fraction: 41.9% ± 3.8% vs 31.4% ± 4.1%, P = .03; cardiac output: 26.7 ± 0.9 mL/min vs 22.7 ± 1.3 mL/min, P = .01; and end-systolic pressure-volume relationship slope: 1.09 ± 0.22 vs 0.59 ± 0.2, P = .02). Conclusions In this study of myocardial ischemia-reperfusion injury, ethyl pyruvate enhanced myocardial adenosine triphosphate levels, attenuated myocardial oxidative injury, decreased infarct size, and preserved cardiac function.

Exercise Cardiac Function in Endurance-Trained Males Versus Females

To examine and compare the exercise cardiac function of endurance-trained (ET) women and men. Six ET women aged 20 to 29 years (mean VO2max = 64 ml.kg-1.min-1) and 9 ET men aged 20 to 29 years (mean VO2max = 69 ml.kg-1.min-1) were included in the study. Cardiac output (Q), stroke volume (SV), diastolic filling rate (DFR), and left ventricular ejection rate (LVER) were compared at rest and during exercise at heart rates (HRs) of 110, 130, 150, 170 bpm, and max. Resting blood volume (BV) and hemoglobin concentration ([Hb]) were also compared. Compared to women, men had a higher BV and [Hb]. At HRmax, men had a higher Q (31.0 +/- 0.6 versus 24.1 +/- 0.9 l.min-1), SV, DFR, and LVER than women. When expressed relative to body mass (kg), there were no gender differences in SVmax, and women had a significantly higher a-v DO2max (approximately 19%) than men. The SV of the men and women did not plateau at a submaximal level but continued to increase progressively to HRmax. During maximal exercise, the DFR was significantly faster than the LVER in the men and the women. When ET men and women are matched for body mass, the gender difference in SVmax is reduced so that it is no longer statistically significant. However, there are still significant gender differences in Q, DFR, LVER, BV, and [Hb] that contribute to a higher VO2max (ml.kg-1.min-1) in ET men compared to women. To augment SVmax, women and men rely to a greater extent on diastolic filling than on left ventricular emptying.

ENHANCED DIASTOLIC FUNCTION IS THE PRIMARY REASON FOR AUGMENTED CARDIAC OUTPUT OF ENDURANCE-TRAINED FEMALES

76 The enhanced cardiac performance of endurance-trained individuals is generally thought to be the result of an augmented systolic function. However, a detailed comparison of the cardiac function of ET versus normally active(NA) females has not been conducted. Cardiac output (Q), stroke volume (SV), diastolic filling rate (DFR) and left ventricular ejection rate (LVER) were examined in 6 ET and 6 NA females, age 18-30 years, using a mixed model experimental design. The acetylene rebreathe technique was employed to measure SV and Q. Cardiac time intervals were determined using an electrocardiogram, ear pulse densitogram and phonocardiogram. Blood volume was measured using the Evan's blue dye technique. SV increased progressively throughout incremental exercise to maximum in ET but plateaued at 150 bpm in NA females. The augmented Q and SV were attributable primarily to DFR rather than LVER and are likely due to an augmented blood volume. TableTable

The effects of medetomidine on cardiac function in normal cats measured by radionuclide ventriculography

To assess the effects of medetomidine, an α 2 -adrenoceptor agonist, on cardiac function, radionuclide ventriculograms (RNV) were performed in 7 normal anesthetised cats before and after im administration of the drug. Ejection fraction (EF), peak ventricular ejection rate (PVER), peak ventricular filling rate (PVFR), time to peak ejection (TPE) and time to peak filling (TPF) were determined. Medetomidine caused significant reductions in EF (baseline 55.0 ± 10.8%, post medetomidine 43.3 ± 10.7%), PVER (baseline 4.38 ± 0.83 EDV/s, post medetomidine 3.28 ± 0.73 EDV/s) and PVFR (baseline 4.46 ± 1.42 EDV/s, post medetomidine 3.05 ± 1.27 EDV/s). There was also a significant decrease in heart rate following medetomidine administration (baseline 115 ± 27.2 bpm, post medetomidine 100 ± 21.2 bpm). The TPE and TPF did not change significantly following medetomidine. The observed decrease in cardiac function may have been caused by a drug-induced increase in systemic vascular resistance, and the bradycardia due to central nervous system depression.