Animal models of right heart failure

Right heart failure may be the ultimate cause of death in patients with acute or chronic pulmonary hypertension (PH). As PH is often secondary to other cardiovascular diseases, the treatment goal is to target the underlying disease. We do however know, that right heart failure is an independent risk factor, and therefore, treatments that improve right heart function may improve morbidity and mortality in patients with PH. There are no therapies that directly target and support the failing right heart and translation from therapies that improve left heart failure have been unsuccessful, with the exception of mineralocorticoid receptor antagonists. To understand the underlying pathophysiology of right heart failure and to aid in the development of new treatments we need solid animal models that mimic the pathophysiology of human disease. There are several available animal models of acute and chronic PH. They range from flow induced to pressure overload induced right heart failure and have been introduced in both small and large animals. When initiating new pre-clinical or basic research studies it is key to choose the right animal model to ensure successful translation to the clinical setting. Selecting the right animal model for the right study is hence important, but may be difficult due to the plethora of different models and local availability. In this review we provide an overview of the available animal models of acute and chronic right heart failure and discuss the strengths and limitations of the different models

Putative Biomarkers for Acute Pulmonary Embolism in Exhaled Breath Condensate

Current diagnostic markers for pulmonary embolism (PE) are unspecific. We investigated the proteome of the exhaled breath condensate (EBC) in a porcine model of acute PE in order to identify putative diagnostic markers for PE. EBC was collected at baseline and after the induction of autologous intermediate-risk PE in 14 pigs, plus four negative control pigs. The protein profiles of the EBC were analyzed using label-free quantitative nano liquid chromatography–tandem mass spectrometry. A total of 897 proteins were identified in the EBCs from the pigs. Alterations were found in the levels of 145 different proteins after PE compared with the baseline and negative controls: albumin was among the most upregulated proteins, with 14-fold higher levels 2.5 h after PE (p-value: 0.02). The levels of 49 other proteins were between 1.3- and 17.1-fold higher after PE. The levels of 95 proteins were lower after PE. Neutrophil gelatinase-associated lipocalin (fold change 0.3, p-value < 0.01) was among the most reduced proteins 2.5 h after PE. A prediction model based on penalized regression identified five proteins including albumin and neutrophil gelatinase-associated lipocalin. The model was capable of discriminating baseline samples from EBC samples collected 2.5 h after PE correctly in 22 out of 27 samples. In conclusion, the EBC from pigs with acute PE contained several putative diagnostic markers of PE

Levosimendan Prevents and Reverts Right Ventricular Failure in Experimental Pulmonary Arterial Hypertension

Background: We investigated whether chronic levosimendan treatment can prevent and revert right ventricular (RV) failure and attenuate pulmonary vascular remodeling in a rat model of pulmonary arterial hypertension (PAH). Methods and Results: PAH was induced in rats by exposure to SU5416 and hypoxia (SuHx). The rats were randomized to levosimendan (3 mg·kg -1 ·d -1) initiated before SuHx (n = 10, PREV), levosimendan started 6 weeks after SuHx (n = 12, REV), or vehicle treatment (n = 10, VEH). Healthy control rats received vehicle (n = 10, CONT). Ten weeks after SuHx, RV function was evaluated by echocardiography, magnetic resonance imaging, invasive pressure-volume measurements, histology, and biochemistry. Levosimendan treatment improved cardiac output (VEH vs. PREV 77 ± 7 vs. 137 ± 6 mL/min; P < 0.0001; VEH vs. REV 77 ± 7 vs. 117 ± 10 mL/min; P < 0.01) and decreased RV afterload compared with VEH (VEH vs. PREV 219 ± 33 vs. 132 ± 20 mm Hg/mL; P < 0.05; VEH vs. REV 219 ± 33 vs. 130 ± 11 mm Hg/mL; P < 0.01). In the PREV group, levosimendan restored right ventriculoarterial coupling (VEH vs. PREV 0.9 ± 0.1 vs. 1.8 ± 0.3; P < 0.05) and prevented the development of pulmonary arterial occlusive lesions (VEH vs. PREV 37 ± 7 vs. 15 ± 6% fully occluded lesions; P < 0.05). Conclusion: Chronic treatment with levosimendan prevents and reverts the development of RV failure and attenuates pulmonary vascular remodeling in a rat model of PAH

Right Ventricular Myocardial Stiffness in Experimental Pulmonary Arterial Hypertension Relative Contribution of Fibrosis and Myofibril Stiffness

BACKGROUND—: The purpose of this study was to determine the relative contribution of fibrosis-mediated and myofibril-mediated stiffness in rats with mild and severe right ventricular (RV) dysfunction. METHODS AND RESULTS—: By performing pulmonary artery banding of different diameters for 7 weeks, mild RV dysfunction (Ø=0.6 mm) and severe RV dysfunction (Ø=0.5 mm) were induced in rats. The relative contribution of fibrosis- and myofibril-mediated RV stiffness was determined in RV trabecular strips. Total myocardial stiffness was increased in trabeculae from both mild and severe RV dysfunction in comparison to controls. In severe RV dysfunction, increased RV myocardial stiffness was explained by both increased fibrosis-mediated stiffness and increased myofibril-mediated stiffness, whereas in mild RV dysfunction, only myofibril-mediated stiffness was increased in comparison to control. Histological analyses revealed that RV fibrosis gradually increased with severity of RV dysfunction, whereas the ratio of collagen I/III expression was only elevated in severe RV dysfunction. Stiffness measurements in single membrane-permeabilized RV cardiomyocytes demonstrated a gradual increase in RV myofibril stiffness, which was partially restored by protein kinase A in both mild and severe RV dysfunction. Increased expression of compliant titin isoforms was observed only in mild RV dysfunction, whereas titin phosphorylation was reduced in both mild and severe RV dysfunction. CONCLUSIONS—: RV myocardial stiffness is increased in rats with mild and severe RV dysfunction. In mild RV dysfunction, stiffness is mainly determined by increased myofibril stiffness. In severe RV dysfunction, both myofibril- and fibrosis-mediated stiffness contribute to increased RV myocardial stiffness