Comparative effects on LV performance, arterial hemodynamics and ventriculo-arterial coupling of two porcine models of coronary artery occlusion

Conference (2007, April 21)

Cardiovascular haemodynamics and ventriculo-arterial coupling in an acute pig model of coronary ischaemia-reperfusion

in Experimental Physiology (2007), 92(1), 127-137

Although reperfusion after coronary occlusion is mandatory for myocardial salvage, reperfusion may trigger a cascade of harmful events (reperfusion injury) adding to myocardial injury. We investigated ... [more ▼]

Although reperfusion after coronary occlusion is mandatory for myocardial salvage, reperfusion may trigger a cascade of harmful events (reperfusion injury) adding to myocardial injury. We investigated effects of reperfusion on left ventricular (LV) haemodynamics and ventriculo-arterial (VA) coupling in pigs following acute myocardial ischaemia induced by coronary artery occlusion. Experiments were performed in six animals, with measurements of cardiac and arterial function at baseline, after 60 min of ischaemia (T60) and after 2 (T180) and 4 h of reperfusion (T300). Ventriculo-arterial coupling was assessed using the ventriculo-arterial elastance ratio of paper, as well as using a 'stiffness coupling' and 'temporal coupling' index. Reperfusion following ischaemia (T180 versus T60) induced a progressive decline in cardiovascular function, evidenced by a decrease in mean arterial blood pressure, cardiac output and ejection fraction which was not restored at T300. Although reperfusion also induced an increase in slope of the end-systolic pressure-volume relationship (ESPVR), the ESPVR curve shifted to the right, associated with a depression of contractile function. Histology demonstrated irreversible myocardial damage at T300. The ventriculo-arterial elastance ratio and the 'stiffness coupling' index were unaffected throughout the protocol, but the 'temporal coupling' parameter indicated a relative shift between heart period and the time constant of the arterial system. It is unlikely that these alterations are attributable to ischaemic injury alone. The combination of both the stiffness and temporal coupling index may provide more information when studying ventriculo-arterial coupling than the more commonly used ventricular end-systolic stiffness/effection arterial elastance (E-es/E-a) ratio. [less ▲]

Study of ventricular interaction during pulmonary embolism using clinical identification in a minimum cardiovascular system model.

in Proceedings of the IEEE (2007)

Cardiovascular disturbances are difficult to diagnose and treat because of the large range of possible underlying dysfunctions combined with regulatory reflex mechanisms that can result in conflicting ... [more ▼]

Cardiovascular disturbances are difficult to diagnose and treat because of the large range of possible underlying dysfunctions combined with regulatory reflex mechanisms that can result in conflicting clinical data. Thus, medical professionals often rely on experience and intuition to optimize hemodynamics in the critically ill. This paper combines an existing minimal cardiovascular system model with an extended integral based parameter identification method to track the evolution of induced pulmonary embolism in porcine data. The model accounts for ventricular interaction dynamics and is shown to predict an increase in the right ventricle expansion index and a decrease in septum volume consistent with known physiological response to pulmonary embolism. The full range of hemodynamic responses was captured with mean prediction errors of 4.1% in the pressures and 3.1% in the volumes for 6 sets of clinical data. Pulmonary resistance increased significantly with the onset of embolism in all cases, as expected, with the percentage increase ranging from 89.98% to 261.44% of the initial state. These results are an important first step towards model-based cardiac diagnosis in the Intensive Care Unit. [less ▲]

The RIFLE criteria: are the foundations robust?

in Critical Care Medicine (2007), 35(11), 26692669-70

Functional residual capacity measurement as a guide during Peep titration in ARDS

in ESICM (2007)

The role of right ventricular-pulmonary arterial coupling to differentiate between effects of inotropic agents in experimental right heart failure

in Critical Care Medicine (2006), 34(11), 2864-2865

Large-pore membrane hemofiltration increases cytokine clearance and improves right ventricular-vascular coupling during endotoxic shock in pigs

in Artificial Organs (2006), 30(7), 560-564

Hemodynamic improvement in patients suffering from both septic shock and renal failure who received hemofiltration suggested that an extrarenal epuration technique could be of interest in patients with ... [more ▼]

Hemodynamic improvement in patients suffering from both septic shock and renal failure who received hemofiltration suggested that an extrarenal epuration technique could be of interest in patients with septic shock alone. However, most of the studies using continuous venovenous hemofiltration (CVVH) in this setting evidenced neither cytokine clearance nor significant reduction in their plasma level. Lack of significant clearance was explained in part by the small size of the membrane pores. Therefore, we investigated the effects of large-pore membrane hemofiltration (LPHF) during endotoxic shock in pigs on interleukin 6 (IL-6) and interleukin 10 (IL-10) clearances, and on right ventricular (RV)-vascular coupling. Thirteen anesthetized healthy pigs weighing 20-30 kg were divided into two groups. In the Endo group (n = 6), the pigs received a 0.5-mg/kg endotoxin infusion over a period of 30 mins from T0 to T30. In the EndoHF group (n = 7), LPHF (cutoff = 80 kDa) and an ultrafiltration rate of 45 mL/kg/h were started 30 mins after the end of the endotoxin infusion, from T60 to T240. In this model of porcine endotoxic shock, LPHF was responsible for a significant clearance of IL-6 (20 mL/min) and Il-10 (14 mL/min), and for an improvement in RV-vascular coupling. [less ▲]

Evaluation of BM-573, a novel TXA(2) synthase inhibitor and receptor antagonist, in a porcine model of myocardial ischemia-reperfusion

in Prostaglandins & Other Lipid Mediators (2006), 79(1-2), 53-73

Aims: To investigate whether BM-573 (N-tert-butyl-N'-[2-(4'-methylphenylam\ino)-5-nitro-benzenesulfonyl]urea), an original combined thromboxane A(2) synthase inhibitor and receptor antagonist, prevents ... [more ▼]

Aims: To investigate whether BM-573 (N-tert-butyl-N'-[2-(4'-methylphenylam\ino)-5-nitro-benzenesulfonyl]urea), an original combined thromboxane A(2) synthase inhibitor and receptor antagonist, prevents reperfusion injury in acutely ischemic pigs. Methods: Twelve animals were randomly divided in two groups: a control group (n = 6) intravenously infused with vehicle, and a BM-573-treated group (n = 6) infused with BM-573 (10 mg kg(-1) h(-1)). In both groups, the left anterior descending (LAD) coronary artery was Occluded for 60 min and reperfused for 240 min. Either vehicle or BM-573 was infused 30 min before LAD occlusion and throughout the experiment. Platelet aggregation induced by arachidonic acid ex vivo measured was prevented by BM-573. Results: In both groups, LAD occlusion decreased cardiac output, ejection fraction, slope of stroke work-end-diastolic volume relationship, and induced end-systolic pressure-volume relationship (ESPVR) rightward shift, while left ventricular afterload increased. Ventriculo-arterial coupling and mechanical efficiency decreased. In both groups, reperfusion further decreased cardiac output and ejection fraction, while ESPVR displayed a further rightward shift. Ventriculo-arterial coupling and mechanical efficiency remained impaired. Area at risk, evidenced with Evans blue, was 33.2 +/- 3.4% of the LV mass (LVM) in both groups, and mean infarct size, revealed by triphenyltetrazolium chloride (TTC), was 27.3 +/- 2.6% of the LVM in the BM-573-treated group (NS). Histological examination and immunohistochemical identification of desmin revealed necrosis in the anteroseptal region similar in both groups, while myocardial ATP dosages and electron microscopy also showed that BM-573 had no cardioprotective effect. Conclusions: These data suggest that BM-573 failed to prevent reperfusion injury in acutely ischemic pigs. (C) 2005 Elsevier Inc. All rights reserved. [less ▲]

Clairance plasmatique des cytokines IL6 et IL10 par hémofiltration avec un filtre à larges pores dans un modèle porcin de choc septique

in Anaesthesiologie und Reanimation (2006), 15(s4),

Comparative effects on LV performance, arterial hemodynamics, and left ventriculo-arterial coupling of two models of coronary artery occlusion in pigs

in CSDS 2006 (2006)