Left Ventricular End-systolic Pressure-volume Relation Research Articles

Acute vasopressin neutralization improves cardiac function in rats with chronic heart failure

Vasopressin is one of the leading pathophysiological drivers of chronic heart failure (CHF) acting via V1a-, V1b- and V2 receptors. Selective V2 and dual V1a-V2 receptor antagonists increases plasma sodium levels, but failed to reduce mortality in clinical studies. Vasopressin neutralization is an original alternative to receptor blockers but its effect in CHF is unknown. For this purpose, we investigated the short-term cardiac and vascular effects of the vasopressin neutralizing aptamer NOX-F37. Left ventricular (LV) function (hemodynamic by LV catheterization) and LV tissue perfusion (MRI) as well as mesenteric artery endothelial function (flow-mediated dilation by arteriography) were determined 2 hours after NOX-F37 administration (80 nM/kg; IP) to rats with CHF induced by left coronary artery ligation. Two hours after administration, NOX-F37 improved LV systolic function, illustrated by the increase in LV end-systolic pressure volume relationship (CHF: 20.2 ± 0.0.7; CHF + NOX: 23.3 ± 1.0 mmHg/RVU; P < 0.05) and diastolic function, illustrated by the decrease in LV end-diastolic pressure volume relationship (CHF: 4.03 ± 0.48; CHF + NOX: 2.06 ± 0.21 mmHg/RVU; P < 0.01), together with an increase in LV tissue perfusion (CHF: 6.12 ± 0.24; CHF + NOX: 10.10 ± 0.26 ml/min/g LV tissue; P < 0.001). However, mesenteric artery flow-induced dilatation was not improved (% dilatation at 150 μL/min; CHF: 10 ± 7; CHF + NOX: 9 ± 8). These results illustrate the immediate beneficial effects of vasopressin neutralization on cardiac function in CHF, confirming the existence of a deleterious vasopressinergic tone in this pathophysiological context. Investigations still needed to evaluate the persistence of effects of vasopressin neutralization over time during chronic and could contribute to the resolution of acute heart failure.

Myocardial repair of bioengineered cardiac patches with decellularized placental scaffold and human-induced pluripotent stem cells in a rat model of myocardial infarction

BackgroundThe creation of a bioengineered cardiac patch (BCP) is a potential novel strategy for myocardial repair. Nevertheless, the ideal scaffold for BCP is unknown.ObjectiveWe investigated whether the decellularized placenta (DP) could serve as natural scaffold material to create a BCP for myocardial repair.Methods and resultsA BCP was created by seeding human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs; 1 × 106/cm2) onto DP. The functional and electrophysiological properties of the BCP were first characterized by in vitro analysis and optical mapping. Next, in vivo therapeutic efficacy of the BCP was evaluated in a rat model of myocardial infarction (MI), created by left descending coronary artery ligation (MI + BCP group), and compared with MI alone (MI group), transplantation of DP (MI + DP group), and hiPSC-CMs (MI + CM group). Cytokine profiling demonstrated that the BCP contained multiple growth and angiogenic factors, including vascular endothelial growth factor, platelet-derived growth factor, insulin-like growth factor-1, basic fibroblast growth factor, angiogenin, and angiopoietin-2. In vitro optical mapping showed that the BCP exhibited organized mechanical contraction and synchronized electrical propagation. RNA sequencing showed that DP enhanced the maturation of hiPSC-CMs compared with the monolayer of cultured hiPSC-CMs. At 4 weeks follow-up, the BCP significantly improved left ventricular (LV) function, as determined by LV ejection fraction, fractional shortening, + dP/dtmax, and end-systolic pressure-volume relationship, compared with the MI, MI + DP, and MI + CM groups. Moreover, histological examination revealed that engraftment of the BCP at the infarct zone decreased infarct size and increased cell retention and neovascularization compared with the MI, MI + DP, and MI + CM groups.ConclusionsOur results demonstrate that a DP scaffold contains multiple growth and angiogenic factors that enhance the maturation and survival of seeded hiPSC-CMs. Transplantation of a BCP is superior to DP or hiPSC-CMs alone in reducing infarct size and improving cell retention and neovascularization, thus providing a novel therapy for myocardial repair following MI.

1963-P: Short- and Long-Term Empagliflozin Treatment Improves Cardiac Function in Rats with Chronic Heart Failure

Introduction: The SGLT2 inhibitor empagliflozin (EMPA) exerts beneficial cardiovascular effects in type-2 diabetes, but whether this occurs in chronic heart failure (CHF) is unknown. Thus we investigated, using a rat model whether EMPA exhibits protective effect in chronic heart failure (CHF). Methods: Rats with CHF were treated with EMPA (30 mg/kg PO for 7 days starting 83 days after coronary artery ligation or 90 days starting 7 days after coronary artery ligation) to assess effects on left ventricular (LV) function and hemodynamics (echocardiography, LV catheterization). Results: After 90 days untreated CHF rats presented LV systolic and diastolic dysfunction, illustrated by the decreases in LV end-systolic pressure (LV ESP) and in LV end-systolic pressure volume-relation (LV ESPVR) as well as the increases in LV end-diastolic pressure (LV EDP) and LV end-diastolic pressure volume-relation (LV EDPVR). Seven- and ninety-day EMPA treatment improved systolic and diastolic LV function, illustrated by the increases in LV ESP and in LV ESPVR as well as the reductions in LV EDP and in LV EDPVR. Conclusion: Short- and long-term EMPA treatment prevents LV dysfunction in rats with CHF. These results suggest that EMPA may exert protective effects in humans with CHF. Disclosure M. Soulié: None. Y. Stephan: None. L. Nicol: None. J. Henry: None. V. Richard: None. M. Pieper: Employee; Self; Boehringer Ingelheim Pharmaceuticals, Inc. P. Mulder: Research Support; Self; Bayer Healthcare Pharmaceuticals Inc., Boehringer Ingelheim Pharmaceuticals, Inc., Poxel SA. Funding Boehringer Ingelheim

Performance comparison of ventricular and arterial dP/dtmax for assessing left ventricular systolic function during different experimental loading and contractile conditions

BackgroundMaximal left ventricular (LV) pressure rise (LV dP/dtmax), a classical marker of LV systolic function, requires LV catheterization, thus surrogate arterial pressure waveform measures have been proposed. We compared LV and arterial (femoral and radial) dP/dtmax to the slope of the LV end-systolic pressure-volume relationship (Ees), a load-independent measure of LV contractility, to determine the interactions between dP/dtmax and Ees as loading and LV contractility varied.MethodsWe measured LV pressure-volume data using a conductance catheter and femoral and radial arterial pressures using a fluid-filled catheter in 10 anesthetized pigs. Ees was calculated as the slope of the end-systolic pressure-volume relationship during a transient inferior vena cava occlusion. Afterload was assessed by the effective arterial elastance. The experimental protocol consisted of sequentially changing afterload (phenylephrine/nitroprusside), preload (bleeding/fluid bolus), and contractility (esmolol/dobutamine). A linear-mixed analysis was used to assess the contribution of cardiac (Ees, end-diastolic volume, effective arterial elastance, heart rate, preload-dependency) and arterial factors (total vascular resistance and arterial compliance) to LV and arterial dP/dtmax.ResultsBoth LV and arterial dP/dtmax allowed the tracking of Ees changes, especially during afterload and contractility changes, although arterial dP/dtmax was lower compared to LV dP/dtmax (bias 732 ± 539 mmHg⋅s− 1 for femoral dP/dtmax, and 625 ± 501 mmHg⋅s− 1 for radial dP/dtmax). Changes in cardiac contractility (Ees) were the main determinant of LV and arterial dP/dtmax changes.ConclusionAlthough arterial dP/dtmax is a complex function of central and peripheral arterial factors, radial and particularly femoral dP/dtmax allowed reasonably good tracking of LV contractility changes as loading and inotropic conditions varied.

Left ventricular mechanoenergetics in excised, cross-circulated rat hearts under hypo-, normo-, and hyperthermic conditions

We investigated the effects of altering cardiac temperature on left ventricular (LV) myocardial mechanical work and energetics using the excised, cross-circulated rat heart model. We analyzed the LV end-systolic pressure–volume relationship (ESPVR) and linear relationship between myocardial oxygen consumption per beat (VO2) and systolic pressure–volume area (PVA; total mechanical energy per beat) in isovolumically contracting rat hearts during hypo- (32 °C), normo- (37 °C), and hyperthermia (42 °C) under a 300-beats per minute pacing. LV ESPVR shifted downward with increasing cardiac temperature. The VO2–PVA relationship was superimposable in these different thermal conditions; however, each data point of VO2–PVA shifted left-downward during increasing cardiac temperature on the superimposable VO2–PVA relationship line. VO2 for Ca2+ handling in excitation–contraction coupling decreased, which was associated with increasing cardiac temperature, during which sarcoplasmic reticulum Ca2+-ATPase (SERCA) activity was suppressed, due to phospholamban phosphorylation inhibition, and instead, O2 consumption for basal metabolism was increased. The O2 cost of LV contractility for Ca2+ also increased with increasing cardiac temperature. Logistic time constants evaluating LV relaxation time were significantly shortened with increasing cardiac temperature related to the acceleration of the detachment in cross-bridge (CB) cycling, indicating increased myosin ATPase activity. The results suggested that increasing cardiac temperature induced a negative inotropic action related to SERCA activity suppression in Ca2+ handling and increased myosin ATPase activity in CB cycling. We concluded that thermal intervention could modulate cardiac inotropism by changing CB cycling, Ca2+ handling, and basal metabolism in rat hearts.

Lack of Cardiac Improvement After Cardiosphere-Derived Cell Transplantation in Aging Mouse Hearts.

Aging is one of the most significant risk factors for cardiovascular diseases, and the incidence of myocardial ischemia increases dramatically with age. Some studies have reported that cardiosphere-derived cells (CDCs) could benefit the injured heart. Nevertheless, the convincing evidence on CDC-induced improvement of aging heart is still limited. In this study, we tested whether the CDCs isolated from neonatal mice could benefit cardiac function in aging mice. We evaluated cardiac function of PBS- (n=15) and CDC-injected (n=19) aging mice. Echocardiography indicated that left ventricular (LV) ejection fraction (57.46%±3.57% versus 57.86%±2.44%) and LV fraction shortening (30.67%±2.41% versus 30.51%±1.78%) showed similar values in PBS- and CDC-injected mice. The diastolic wall thickness of LV was significantly increased after CDC injection, resulting in reduced diastolic LV volume. The pulse-wave Doppler and tissue Doppler imaging indicated that aging mice receiving PBS or CDC injection presented similar values of the peak early transmitral flow velocity, the peak late transmitral flow velocity, the ratio of the peak early transmitral flow velocity to the peak late transmitral flow velocity, and the ratio of the peak early transmitral flow velocity to the peak early diastolic mitral annular velocity, respectively. Pressure-volume loop experiment indicated that the LV end-diastolic pressure-volume relationship and end-systolic pressure-volume relationship were comparable in both PBS- and CDC-injected mice. Postmortem analysis of aging mouse hearts showed similar fibrotic degree in the 2 groups. In addition, the aging markers showed comparable expression levels in both PBS- and CDC-injected mice. The systemic aging performance measures, including exercise capacity, hair regrowth capacity, and inflammation, showed no significant improvement in CDC-injected mice. Finally, the telomere length was comparable between PBS- and CDC-injected mice. Together, these results indicate that CDCs do not improve heart function and systemic performances in aging mice.

Short- and long-term administration of the non-steroidal mineralocorticoid receptor antagonist finerenone opposes metabolic syndrome-related cardio-renal dysfunction.

To determine whether non-steroidal mineralocorticoid receptor (MR) antagonists oppose metabolic syndrome-related end-organ, i.e. cardiac, damage. In Zucker fa/fa rats, a rat model of metabolic syndrome, we assessed the effects of the non-steroidal MR antagonist finerenone (oral 2 mg/kg/day) on left ventricular (LV) function, haemodynamics and remodelling (using echocardiography, magnetic resonance imaging and biochemical methods). Long-term (90 days) finerenone modified neither systolic blood pressure nor heart rate, but reduced LV end-diastolic pressure and LV end-diastolic pressure-volume relationship, without modifying LV end-systolic pressure and LV end-systolic pressure-volume relationship. Simultaneously, long-term finerenone reduced both LV systolic and diastolic diameters, associated with reductions in LV weight and LV collagen density, while proteinuria and renal nGAL expression were reduced. Short-term (7 days) finerenone improved LV haemodynamics and reduced LV systolic diameter, without modifying LV diastolic diameter. Moreover, short-term finerenone increased myocardial tissue perfusion and reduced myocardial reactive oxygen species, while plasma nitrite levels, an indicator of nitric oxide (NO) bio-availability, were increased. In rats with metabolic syndrome, the non-steroidal MR antagonist finerenone opposed metabolic syndrome-related diastolic cardiac dysfunction and nephropathy. This involved acute effects, such as improved myocardial perfusion, reduced oxidative stress/increased NO bioavailability, as well as long-term effects, such as modifications in the myocardial structure.

Protein tyrosine phosphatase 1B inactivation limits aging-associated heart failure in mice

We have previously shown that protein tyrosine phosphatase 1B (PTP1B) inactivation in mice [PTP1B-deficient (PTP1B-/-) mice] improves left ventricular (LV) angiogenesis, perfusion, remodeling, and function and limits endothelial dysfunction after myocardial infarction. However, whether PTP1B inactivation slows aging-associated cardiovascular dysfunction remains unknown. Wild-type (WT) and PTP1B-/- mice were allowed to age until 18 mo. Compared with old WT mice, in which aging increased the LV mRNA expression of PTP1B, old PTP1B-/- mice had 1) reduced cardiac hypertrophy with decreased LV mRNA levels of hypertrophic markers and atrial and brain natriuretic peptides, 2) lower LV fibrosis (collagen: 16 ± 3% in WT mice and 5 ± 3% in PTP1B-/- mice, P < 0.001) with decreased mRNA levels of transforming growth-factor-β1 and matrix metalloproteinase-2, and 3) higher LV capillary density and lower LV mRNA level of hypoxic inducible factor-1α, which was associated over time with a higher rate of proangiogenic M2 type macrophages and a stable LV mRNA level of VEGF receptor-2. Echocardiography revealed an age-dependent LV increase in end-diastolic volume in WT mice together with alterations of fractional shortening and diastole (transmitral Doppler E-to-A wave ratio). Invasive hemodynamics showed better LV systolic contractility and better diastolic compliance in old PTP1B-/- mice (LV end-systolic pressure-volume relation: 13.9 ± 0.9 in WT mice and 18.4 ± 1.6 in PTP1B-/- mice; LV end-diastolic pressure-volume relation: 5.1 ± 0.8 mmHg/relative volume unit in WT mice and 1.2 ± 0.3 mmHg/relative volume unit in PTP1B-/- mice, P < 0.05). In addition, old PTP1B-/- mice displayed a reduced amount of LV reactive oxygen species. Finally, in isolated resistance mesenteric arteries, PTP1B inactivation reduced aging-associated endothelial dysfunction (flow-mediated dilatation: -0.4 ± 2.1% in WT mice and 8.2 ± 2.8% in PTP1B-/- mice, P < 0.05). We conclude that PTP1B inactivation slows aging-associated LV remodeling and dysfunction and reduces endothelial dysfunction in mesenteric arteries. NEW & NOTEWORTHY The present study shows that protein tyrosine phosphatase 1B inactivation in aged mice improves left ventricular systolic and diastolic function associated with reduced adverse cardiac remodeling (hypertrophy, fibrosis, and capillary rarefaction) and limits vascular endothelial dysfunction. This suggests that protein tyrosine phosphatase 1B inhibition could be an interesting treatment approach in age-related cardiovascular dysfunction.

Ventricular Energetics in Pediatric Left Ventricular Assist Device Patients: A Retrospective Clinical Study.

The aim of this study is to estimate the trend of right and left energetic parameters in left ventricular assist device (LVAD) pediatric patients. Echocardiographic data were retrospectively collected at the baseline, in the acute phase after and at the monthly follow-ups till the LVAD explantation to estimate left and right ventricular energetic parameters. A significant relationship between the left and right ventricular energetic parameter trends was found along all the study period. Left ventricular end-systolic pressure-volume relationship improved till the follow-up of 2 months and then progressively decreases. Left arteroventricular coupling decreases after the LVAD, and right arteroventricular coupling decreases at the short-term follow-up. Left ventricular external work, potential energy, and pressure-volume area decrease at the short-term follow-up and then increase progressively. Right ventricular external work, potential energy, and pressure-volume area increase after the LVAD implantation. Left (right) cardiac mechanical efficiency is improved (worsened) by the LVAD. Energetic variables show that the LVAD benefits could decrease over time. A continuous and patient tailored LVAD setting could contribute to prolong LVAD benefits. The introduction of energetic parameters could lead to a more complete evaluation of LVAD patients' outcome which is a multiparametric process.

Dependence of Cardiac Systolic Function on Elevated Fatty Acid Availability in Obese, Insulin-Resistant Rats

BackgroundClinical data advocating an adverse effect of obesity on left ventricular (LV) systolic function independent of comorbidities is controversial. We hypothesized that in obesity with prediabetic insulin resistance, circulating fatty acids (FAs) become a valuable fuel source in the maintenance of normal systolic function. MethodsMale Wistar rats were fed a high caloric diet for 32 weeks to induce obesity. Myocardial LV systolic function was assessed using echocardiography and isolated heart preparations. ResultsAortic output was reduced in obese rat hearts over a range of filling pressures (for example: 15 cmH2O, obese: 32.6 ± 1.2 ml/min vs control: 46.2 ± 0.9 ml/min, P < .05) when perfused with glucose alone. Similarly, the slope of the LV end-systolic pressure-volume relationship decreased, and there was a right shift in the LV end-systolic stress-strain relationship as determined in Langendorff perfused, isovolumic rat heart preparations in the presence of isoproterenol (10−8M) (LV systolic stress-strain relationship and a reduced load-independent intrinsic systolic myocardial function, obese: 791 ± 62 g/cm2 vs control: 1186 ± 74 g/cm2, P < .01). The addition of insulin to the perfusion buffer improved aortic output, whereas the addition of FAs completely normalized aortic output. LV function was maintained in obese animals in vivo during an inotropic challenge. ConclusionsElevated circulating FA levels may be important to maintain myocardial systolic function in the initial stages of obesity and insulin resistance.

Selective Heart Rate Reduction Improves Metabolic Syndrome-related Left Ventricular Diastolic Dysfunction.

Enhanced heart rate observed in metabolic syndrome (MS) contributes to the deterioration of left ventricular (LV) function via impaired LV filling and relaxation, increased myocardial O2 consumption, and reduced coronary perfusion. However, whether heart rate reduction (HRR) opposes LV dysfunction observed in MS is unknown. We assessed in Zucker fa/fa rats, a rat model of MS, the cardiovascular effects of HRR induced by the If current inhibitor S38844 (3 mg · kg(-1) · d(-1)). Delayed short-term (4 days) and long-term (90 days) HRR induced by S38844 reduced LV end-diastolic pressure and LV end-diastolic pressure-volume relation, increased myocardial tissue perfusion, decreased myocardial oxidized glutathione levels, and preserved cardiac output, without modifying LV end-systolic pressure and LV end-systolic pressure-volume relation, although only long-term S38844 opposed LV collagen accumulation. Long-term S38844 improved flow-induced endothelium-dependent dilatation of mesenteric arteries, while metabolic parameters, such as plasma glucose levels, and Hb1c, were never modified. In rats with MS, HRR induced by the If inhibitor S38844 improved LV diastolic function and endothelium-dependent vascular dilatation, independent from modifications in metabolic status. Moreover, this improvement in cardiac function involves not only immediate effects such as improved myocardial perfusion and reduced oxidative stress but also long-term effects such as modifications in the myocardial structure.

Abstract 12583: C-Type Natriuretic Peptide Improves Left Ventricular Systolic and Diastolic Functional Performance at Rest and During Exercise After Heart Failure

Background: In heart failure (HF), the impaired left ventricular (LV) arterial coupling and diastolic dysfunction present at rest are exacerbated during exercise (Ex). C-type natriuretic peptide (CNP), the third member of the natriuretic peptide family produced by the vascular endothelium and heart is elevated in HF. However, its functional effects are unclear. We tested the hypotheses that CNP with vasodilating, natriuretic, and lusitropic actions may prevent this abnormal Ex response after HF. Methods: We assessed the effects of CNP on LV functional performance at rest and during submaximum Ex (3.5-5.5 mph for 6-8 min) in 10 instrumented dogs with pacing-induced HF. Since CNP mediated its biological actions via cGMP, we also measured plasma cGMP levels in response to CNP infusion at rest before and after HF. Results: CNP (2 μg/kg plus 0.4 μg/kg/min, iv, 20 min) caused a similar increase in cGMP levels before (7.2±3.8 to 24.7±4.9 pmol/ml) and after HF (20.2±4.4 to 71.6±5.0 pmol/ml). After HF, at rest, CNP reduced LV end-systolic pressure (P ES , CNP: 93 vs Baseline: 104 mmHg), arterial elastance (E A , 8.3 vs 11.7 mmHg/ml) and end-diastolic pressure (P ED , 37.2 vs 42.4 mmHg) (p&lt;0.05). The peak mitral flow (dV/dt max , 201±51 vs 160±34ml/sec) was also increased due to decreased minimum LVP (LVP min , 17.1 vs 23.8 mmHg) and the time constant of LV relaxation (t, 40±4 vs 48±6 msec) (p&lt;0.05). In addition, the slope of LV end-systolic pressure-volume relations (E ES ) was increased (5.6±0.7 vs 4.2±0.9 mmHg/ml). The LV-arterial coupling, quantified as E ES /E A , was improved (0.69±0.22 vs 0.48±0.16) (p&lt;0.05). The beneficial effects persisted during Ex. At matched levels of Ex, treatment with CNP, Ex-induced significantly less increases in P ES (ΔP= 3.4±0.5 vs 7.4±0.8 mmHg), mean LAP (ΔP= -3.1±2.2 vs 3.6±2.9 mmHg), and LVP min (ΔP= -3.6±1.4 vs 1.4±1.2 mmHg) (p&lt;0.05). With CNP, t was much shortened (Δ= -0.8±4.0 vs 2.8±3.2 ms), and the peak mitral flow was further augmented (ΔdV/dt max , 75±20 vs 43±12 ml/sec) (p&lt;0.05). Conclusion: After HF, the generation of cGMP in response to CNP is not blunted. CNP produces arterial vasodilatation and augments LV contraction, relaxation, diastolic filling and LV arterial coupling, thus improving LV performance, both at rest and during Ex after HF.

Nonlinear multiscale circulation model reproducable linear end-systolic pressure-volume relationship.

As a well-known property of the heart, many studies has reported that the left ventricular end-systolic pressure-volume relationship (ESPVR) is linear. However, the reason of the linearity is poorly understood. This article presents a multiscale circulation model to be a tool for theoretical analyses on the mechanism of the linearity of ESPVR. The model is composed of three sub-models; a detailed closed-loop lumped-parameter model for cardiovascular system, geometric left ventricle model, a comprehensive ventricular myocyte model. Although the present model integrates nonlinear sub-models, the model can successfully reproduce highly linear ESPVR without any arbitrary modifications.

Functional evaluation of human donation after cardiac death donor hearts using a continuous isolated myocardial perfusion technique: Potential for expansion of the cardiac donor population

To investigate the resuscitation potential and contractile function in adult human donation after cardiac death (DCD) hearts by ex vivo perfusion. With institutional review board approval and under the DCD protocol at the University of Wisconsin (UW) Organ Procurement Organization, 5 brain dead (BD) and 5 DCD donor hearts were evaluated. All BD hearts were declined for clinical transplantation because of coronary artery disease, advanced age, or social history. All hearts were preserved by flushing and cold storage with UW solution. By using our ex vivo perfusion system, the left ventricular end systolic pressure-volume relationship (LV-ESPVR) was assessed for 2 hours of oxygenated blood reperfusion. All BD (n = 5) and 4 DCD hearts were successfully resuscitated. One DCD heart was unable to be resuscitated due to prolonged warm ischemic time (WIT; 174 minutes). Mean WIT for resuscitated DCD hearts (from extubation to flushing with cold UW solution) was 34 ± 3 minutes (range, 26 to 40 minutes); mean cold ischemic time for BD donors was 211 ± 31 minutes compared with 177 ± 64 minutes for DCD donors. The calculated LV-ESPVRs for BD hearts after 1 and 2 hours of reperfusion were 6.9 ± 0.7 and 5.7 ± 1.0 mm Hg/mL, respectively; LV-ESPVRs for DCD hearts after 1 and 2 hours of reperfusion were 5.6 ± 1.5 (P = .45) and 3.0 ± 0.7 mm Hg/mL (P = .07), respectively. We successfully resuscitated and measured ex vivo cardiac function in human DCD and BD donor hearts. Resuscitation potential in DCD hearts was achieved when the WIT was less than 40 minutes. Contractile performance in DCD hearts tended to be lower compared with BD hearts. Further investigation with longer reperfusion periods seems warranted.

0213: Gevokizumab, an IL1-beta modulating antibody exerts promising cardioprotective effects against ischemia-reperfusion injury in diabetic rats

Enhanced myocardial interleukin-1 beta (IL1-β) production is involved in ischemia/reperfusion (I/R) induced left ventricular (LV) dysfunction. We tested neutralization of IL-1β as a potential therapeutic target for the treatment of I/R induced LV dysfunction. We assessed in diabetic (Goto Kakizaki, GK) rats the preventive effects of gevokizumab, a potent modulator of IL-1β, administered once a week, started 4 weeks prior to a 20 min of transient ischemia induced by left coronary artery occlusion and continued 90 days after I/R, on LV remodeling/function (echocardiography) 7 and 90 days after I/R. LV hemodynamics (LV catheterization), LV tissue perfusion (MRI) and LV collagen density (image analysis) were assessed 90 days after I/R. I/R induced early LV expansion followed by late LV dilatation, associated with LV dysfunction as well as after 90 days, reduced LV tissue perfusion and LV collagen accumulation. Gevokizumab limited both early LV expansion as well as late LV dilatation, associated with an improved LV function. Ninety days after I/R, gevokizumab improved both LV systolic and LV diastolic functions, illustrated by the increase in LV end-systolic pressure volume relation, and the reductions in LV end-diastolic pressure and LV end-diastolic pressure volume relation. Moreover, long-term gevokizumab moderately increased LV tissue perfusion and significantly reduced LV collagen density. Our results, obtained using a clinically relevant model of I/R, suggest a therapeutic benefit of the IL-1β modulating antibody, gevokizumab, in myocardial I/R injury. LVDD: left ventricular diastolic diameters; LVFS:LV fractional shortening; LVESPVR and LVEDPVR: LV end-diastolic and end-systolic pressure volume relations. *:p<0.05 vs GK; † p<0.05 vs GK I/R

Impact of Acute Changes of Left Ventricular Contractility on the Transvalvular Impedance: Validation Study by Pressure-Volume Loop Analysis in Healthy Pigs

BackgroundThe real-time and continuous assessment of left ventricular (LV) myocardial contractility through an implanted device is a clinically relevant goal. Transvalvular impedance (TVI) is an impedentiometric signal detected in the right cardiac chambers that changes during stroke volume fluctuations in patients. However, the relationship between TVI signals and LV contractility has not been proven. We investigated whether TVI signals predict changes of LV inotropic state during clinically relevant loading and inotropic conditions in swine normal heart.MethodsThe assessment of RVTVI signals was performed in anesthetized adult healthy anesthetized pigs (n = 6) instrumented for measurement of aortic and LV pressure, dP/dtmax and LV volumes. Myocardial contractility was assessed with the slope (Ees) of the LV end systolic pressure-volume relationship. Effective arterial elastance (Ea) and stroke work (SW) were determined from the LV pressure-volume loops. Pigs were studied at rest (baseline), after transient mechanical preload reduction and afterload increase, after 10-min of low dose dobutamine infusion (LDDS, 10 ug/kg/min, i.v), and esmolol administration (ESMO, bolus of 500 µg and continuous infusion of 100 µg·kg−1·min−1).ResultsWe detected a significant relationship between ESTVI and dP/dtmax during LDDS and ESMO administration. In addition, the fluctuations of ESTVI were significantly related to changes of the Ees during afterload increase, LDDS and ESMO infusion.ConclusionsESTVI signal detected in right cardiac chamber is significantly affected by acute changes in cardiac mechanical activity and is able to predict acute changes of LV inotropic state in normal heart.

Gene deletion of protein tyrosine phosphatase 1B limits cardiovascular dysfunction and mortality during endotoxinic shock

Sepsis-associated cardiovascular dysfunction is one of the main causes of mortality in critically ill patients. PTP1B is negative regulator of insulin signaling and endothelial Nitric Oxide (NO) production, two mechanisms likely involved in the pathogenesis of sepsis. We recently showed that gene deletion or pharmacological inhibition of PTP1B improves endothelial dysfunction and reduces the severity of heart failure. The aim of the present study was to assess the effect of PTP1B gene deletion on lipopolysaccharide (LPS)-induced cardiovascular dysfunction and mortality in mice. PTP1B-/- or wild-type (WT) mice received LPS (15mg/kg) or vehicle followed by subcutaneous saline resuscitation (30ml/kg). LPS significantly enhanced cardiac and arterial PTP1B mRNA expression. Compared with WT, PTP1B-/- mice displayed markedly reduced mortality (Survival 4 days after LPS: WT: 0%; PTP1B-/- 70%, p<0.01), associated with a higher locomotor activity. Evaluation of vascular function 8h after LPS in isolated mesenteric resistance arteries (arteriograph system) showed that PTP1B-/- LPS mice had improved contractile response to phenylephrine, and restored flow mediated, NO dependent-dilatation (% dilatation to 200μl/min: WT 6,3±3; PTP1B-/- 16,5±2, p<0.05) associated with significant increases in phosphorylation of Akt and eNOS, and reduced mRNA expression of VCAM-1, ICAM-1, COX-2, IL-1β, iNOS and Gp91phox (PCR). Evaluation of left ventricular (LV) function by echocardiography, and pressure-volume curves 8h after LPS revealed reduced cardiac dysfunction in PTP1B-/- mice as shown by an increased LV fractional shortening (WT 17,3±1; PTP1B-/- 24±1, p<0.05) and LV end systolic pressure-volume relation (WT 16±2; PTP1B-/- 20±2, p<0.05) together with reduced LV end diastolic pressure-volume relation (WT 4,7±1,7; PTP1B-/- 2.4±0.9 mmHg/RVU, p<0.05). Improved cardiac contractility was also observed ex-vivo in hearts isolated and perfused 8h after LPS (LV Developed Pressure: WT 25±5; PTP1B-/- 50±5 mmHg, p<0.05). Improved cardiac function was associated with significant decreases in myocardial markers of inflammation and oxidative stress (VCAM-1, ICAM-1, CD45, IL-1β, TNF-α and Gp91phox), reduced P38 and ERK1/2 phosphorylation and limited decrease of phospholamban phosphorylation (WT -42%; PTP1B-/- -22.8, p<0.05). Thus, we demonstrate for the first time that PTP1B gene deletion protects against lipopolysaccharide-induced cardiovascular dysfunction and mortality. These results suggest that PTP1B is an attractive target for the treatment of sepsis.

Abstract 062: Mitoubiquinone Decreases Reactive Oxygen Species Production and Improves Cardiac Efficiency in Chronic Volume Overload

Background: The hemodynamic stress of left ventricular (LV) volume overload (VO) produces LV dysfunction accompanied by mitochondrial and cytoskeletal disruption in cardiomyocytes. Because mitochondria are both a source and target of reactive oxygen species (ROS), we hypothesize myocyte damage and LV dysfunction are mediated by mitochondrially produced ROS and can be attenuated by the mitochondrially targeted antioxidant, mitoubiquinone (MitoQ). Methods: Aortocaval fistula (ACF) was induced for 8 weeks in adult rats ± MitoQ. Echocardiography and high-fidelity LV pressure catheter recordings were used to study the LV end-systolic pressure-volume relationship and cardiac efficiency. Isolated cardiomyocytes were loaded with Carboxy-H2DFFDA (CM-DCF) and tetramethylrhodamine (TMRM) to measure mitochondrial ROS production and membrane potential. Results: Isolated cardiomyocyte studies demonstrated increased ROS production and decreased mitochondrial membrane potential in VO animals, both of which were attenuated with MitoQ. Treatment with MitoQ demonstrated a strong trend toward improvement in LV contractility, as cardiac efficiency improved significantly in MitoQ-treated VO animals. Untreated VO animals exhibited mitochondrial swelling and myofibrillar disruption that was prevented by MitoQ. Conclusion: These studies suggest an early interplay between mitochondrial-derived ROS production and cardiac ultrastructure and function.

Pharmacologically Induced Hypothermia with WIN55,212-2 and Extracorporeal Life Support after Cardiac Arrest as a Preservation Strategy for Heart Transplantation

Purpose To investigate the hypothesis that induction of therapeutic hypothermia with cannabinoid receptor agonist WIN55,212-2 and extracorporeal life support (ECLS) after cardiac arrest is an effective heart preservation strategy. Methods and Materials Ventricular fibrillation (VF) was induced in male Wistar rats. After 10 min of untreated VF, venoarterial ECLS was instituted and rats were randomized to three groups of ten: normothermia, therapeutic hypothermia (32°C) and pharmacological hypothermia by WIN55,212 intravenous infusion (1 mg/kg/h). After 120 minutes heterotopic heart transplantation was performed in syngeneic donors using a working heart model. After 24 hours left ventricular (LV) systolic and diastolic functions were evaluated at different preloads using a conductance catheter. Results WIN55,212-2 led to a significantly better recovery of the slope of the LV end-systolic pressure volume relationship (Ees) and Preload recruitable stroke work (PRSW) than hypothermia and normothermia: as percent of baseline 87+12 vs 54+9 vs 39+11 and 88+11 vs 59+10 vs 33+8 respectively (p.01). LV stiffness expressed by end-diastolic pressure volume relationship (EDPVR) was significantly lower after WIN55,212-2 administration (p Conclusions Pharmacologically induced hypohermia with WIN55,212-2 during ECLS improve myocardial protection through activation of the pro-survival kinase Akt and ERK and could be an organ preservation strategy after cardiac arrest.

Abstract 18789: Pharmacologically Induced Hypothermia with Cannabinoid Receptor Agonist WIN55,212-2 vs Mild Therapeutic Hypothermia in a Rat Model of Cardiac Arrest with Extracorporeal Life Support

BACKGROUND: To compare the hemodynamic, cardioprotective and metabolic effects of cannabinoid receptor agonist WIN55,212-2 with mild therapeutic hypothermia and normothermic control on post-resuscitation myocardial function in a rat model of extracorporeal life support (ECLS). METHODS AND RESULTS: Ventricular fibrillation (VF) was induced in male Wistar rats. After 10 min of untreated VF, venoarterial ECLS was instituted for 60 min. At the beginning of ECLS animals were randomized to three groups of ten: normothermia, hypothermia (32°C) and WIN55,212 intravenous infusion (1 mg/kg/h). Cooling to 32°C or normothermia or drug infusion lasted for the entire ECLS. Plasma samples and myocardial biopsies were obtained and left-ventricular (LV) function was assessed by a conductance catheter at baseline and after weaning from ECLS. WIN55,212-2 administration produced pharmacologic hypothermia (32-34°C) and led to a significantly better recovery of the slope of the LV end-systolic pressure volume relationship (Ees) and Preload recruitable stroke work (PRSW) than hypothermia and normothermia: as percent of baseline 87+12 vs 54+9 vs 39+11 and 88+11 vs 59+10 vs 33+8 respectively (p&lt;.01). LV stiffness expressed by end-diastolic pressure volume relationship (EDPVR) was significantly lower after WIN55,212-2 administration (p&lt;.05). LV relaxation described by Tau was preserved after WIN55,212-2 treatment but not after hypothermia or normothermia (p&lt;.01). WIN55,212-2 and not hypothermia significantly increased phosphorylation of the kinase ERK1 and 2 (2.8+0.4 and 2.5+0.3 vs 0.5+0.2 and 0.4+0.1 -fold of baseline levels) (p&lt;.01). Both WIN55,212-2 and hypothermia but not normothermia increased phosphorylation of Akt. This resulted in a reduced cardiomyocyte apoptotic index (TUNEL, p&lt;.01). WIN55,212-2 but not hypothermia nor normothermia preserved high energy phosphates content and energy charge and reduced lactate plasma concentration. CONCLUSIONS: Pharmacologically induced hypothermia with WIN55,212-2 was more effective than mild therapeutic hypothermia in recovering myocardial function after ECLS and in improving myocardial protection through activation of the pro-survival kinases Akt and ERK1/2.