Ventricular-arterial uncoupling in heart failure with preserved ejection fraction after myocardial infarction in dogs - invasive versus echocardiographic evaluation.

BACKGROUND: Heart failure with preserved left ventricular ejection fraction and abnormal diastolic function is commonly observed after recovery from an acute myocardial infarction. The aim of this study was to investigate the physiopathology of heart failure with preserved ejection fraction in a model of healed myocardial infarction in dogs. METHODS: Echocardiography, levels of neurohormones and conductance catheter measurements of left ventricular pressure-volume relationships were obtained in 17 beagle dogs 2 months after a coronary artery ligation, and in 6 controls. RESULTS: Healed myocardial infarction was associated with preserved echocardiographic left ventricular ejection fraction (0.57 +/- 0.01, mean +/- SEM) and altered Doppler mitral indices of diastolic function. NT-proBNP was increased, aldosterone was decreased, and norepinephrine was unchanged. Invasive measurements showed a markedly decreased end-systolic elastance (2.1 +/- 0.2 vs 6.1 +/- 0.8, mmHg/ml, p < 0.001) and end-systolic elastance to effective arterial elastance ratio (0.6 +/- 0.1 vs 1.4 +/- 0.2, p < 0.001), with altered active relaxation (dP/dtmin -1992 +/- 71 vs -2821 +/- 305, mmHg/s, p < 0.01) but preserved left ventricular capacitance (70 +/- 6 vs 61 +/- 3, ml at 20 mmHg, p = NS) and stiffness constant. Among echocardiographic variables, the wall motion score index was the most reliable indicator of cardiac contractility while E', E/A and E'/A' were correlated to dP/dtmin. CONCLUSIONS: In the canine model of healed myocardial infarction induced by coronary ligation, heart failure is essentially characterized by an altered contractility with left ventricular-arterial uncoupling despite vascular compensation rather than by abnormal diastolic function.

Cell therapy with autologous bone marrow mononuclear stem cells is associated with superior cardiac recovery compared with use of nonmodified mesenchymal stem cells in a canine model of chronic myocardial infarction.

OBJECTIVE: Stem cell therapy can facilitate cardiac repair in infarcted myocardium, but the optimal cell type remains uncertain. We conducted a randomized, blind, and placebo-controlled comparison of autologous bone marrow mononuclear cell and mesenchymal stem cell therapy in a large-animal model of chronic myocardial infarction. METHODS: Eleven weeks after coronary ligation, 24 dogs received intramyocardial injections of mononuclear cells (227.106 +/- 32.106 cells), mesenchymal stem cells (232.106 +/- 40.106 cells), or placebo (n = 8 per group). Cardiac performance and remodeling were assessed up to 16 weeks' follow-up. RESULTS: At echocardiographic analysis, the wall motion score index showed a sustained improvement after mononuclear cell transfer (from 1.8 +/- 0.1 to 1.5 +/- 0.07) and a moderate late improvement after mesenchymal stem cell transfer (from 1.9 +/- 0.08 to 1.7 +/- 0.1). After mononuclear cell transfer, end-systolic elastance increased (from 2.23 +/- 0.25 to 4.42 +/- 0.55 mm Hg/mL), infarct size decreased (from 13% +/- 0.67% to 10% +/- 1.17%), N-terminal B-type natriuretic propeptide level decreased (from 608 +/- 146 to 353 +/- 118 pmol/L), and relative wall area and arterial density increased. Vascular endothelial growth factor receptor 2 expression was upregulated in the border zone. No change in cardiac contractility or histologic parameters was noted in the mesenchymal stem cell group. CONCLUSION: In a canine model of chronic myocardial infarction, bone marrow mononuclear cell transfer is superior to mesenchymal stem cell transfer in improvement of cardiac contractility and regional systolic function and reduction in infarct size and plasma N-terminal B-type natriuretic propeptide level. Functional improvement is associated with a favorable angiogenic environment and neovascularization.

Acute pulmonary embolism: relationships between ground-glass opacification at thin-section CT and hemodynamics in pigs.

PURPOSE: To investigate the link between acute pulmonary embolism (PE) and occurrence of ground-glass opacity (GGO) and the relationships between this occurrence and hemodynamics in an animal model of acute PE. MATERIALS AND METHODS: In this animal care committee-approved study, PE was achieved by injecting blood clots through a central venous catheter in five pigs. Thin-section computed tomography (CT) and hemodynamic measurements-mean pulmonary arterial pressure (Ppa), systemic and pulmonary cardiac outputs, effective pulmonary capillary pressure (Pc'), right atrial pressure, and occluded Ppa-were obtained before and after PE was achieved. Severity and extent of GGO were assigned scores subjectively, and lung attenuation was measured on each scan. Measurements were performed every 20 minutes after PE was achieved, for a total duration of 60 minutes. Finally, CT pulmonary angiography was performed. Lung attenuation was measured in unobstructed and obstructed zones. Measurements were compared by using analysis of variance and Student t test when appropriate. Correlations were investigated through Spearman rank correlation test. RESULTS: In the unobstructed lung zones, GGO appeared immediately after PE was achieved, with an increased mean lung attenuation (P < .001). Mean Ppa and Pc' increased immediately after PE was achieved, and Pc' reached 23 mm Hg, a value associated with pulmonary edema. Cardiac output did not change (P = .238). Lung attenuation and subjective score assignment for GGO were significantly correlated with Ppa and Pc' (P < .001 to .002). CONCLUSION: Acute PE induces GGO in unobstructed lung zones. Given constant cardiac output, GGO is likely to be related to redistribution of blood flow from obstructed to unobstructed lung zones and occurs at a pressure consistent with pulmonary edema.