Search

We evaluated the relationships between regional myocardial strain measured by speckle tracking echocardiography and viability, fibrosis, hypertrophy and oxygen consumption in the infarcted or remote myocardium in a pig model of chronic myocardial infarction (MI). Thirteen farm pigs with surgical occlusion of the left anterior descending coronary artery and five sham-operated pigs were studied 3 mo post-MI. Computed tomography revealed significant left ventricle remodeling. Reduced radial or circumferential strain identified areas of transmural infarction (area under the curve: 0.82 and 0.79, respectively). In the remote non-infarcted area, radial strain correlated inversely with the amount of fibrosis (r = -0.66, p = 0.04) and myocyte hypertrophy (r = -0.68, p = 0.03). Radial strain rate inversely correlated with myocardial resting oxygen consumption assessed with 11C-labeled acetate positron emission tomography (r = -0.71, p = 0.006). In conclusion, myocardial strain and strain rate reflect fibrosis, hypertrophy and oxygen consumption of the remote areas after MI. [ABSTRACT FROM AUTHOR]

Aims: To study myocardial substrate uptake, structure and function, before and after bariatric surgery, to clarify the interaction between myocardial metabolism and cardiac remodelling in morbid obesity. Methods: We studied 46 obese patients (age 44 ± 10 years, body mass index [BMI] 42 ± 4 kg/m2), including 18 with type 2 diabetes (T2D) before and 6 months after bariatric surgery and 25 healthy age‐matched control group subjects. Myocardial fasting free fatty acid uptake (MFAU) and insulin‐stimulated myocardial glucose uptake (MGU) were measured using positron‐emission tomography. Myocardial structure and function, and myocardial triglyceride content (MTGC) and intrathoracic fat were measured using magnetic resonance imaging and magnetic resonance spectroscopy. Results: The morbidly obese study participants, with or without T2D, had cardiac hypertrophy, impaired myocardial function and substrate metabolism compared with the control group. Surgery led to marked weight reduction and remission of T2D in most of the participants. Postoperatively, myocardial function and structure improved and myocardial substrate metabolism normalized. Intrathoracic fat, but not MTGC, was reduced. Before surgery, BMI and MFAU correlated with left ventricular hypertrophy, and BMI, age and intrathoracic fat mass were the main variables associated with cardiac function. The improvement in whole‐body insulin sensitivity correlated positively with the increase in MGU and the decrease in MFAU. Conclusions: In the present study, obesity and age, rather than myocardial substrate uptake, were the causes of cardiac remodelling in morbidly obese patients with or without T2D. Cardiac remodelling and impaired myocardial substrate metabolism are reversible after surgically induced weight loss and amelioration of T2D. [ABSTRACT FROM AUTHOR]

Background: We evaluated echocardiographic area-length methods to measure left ventricle (LV) volumes and ejection fraction (EF) in parasternal short axis views in comparison with cardiac computed tomography (CT) in pigs with chronic myocardial infarction (MI).Methods: Male farm pigs with surgical occlusion of the left anterior descending coronary artery (n = 9) or sham operation (n = 5) had transthoracic echocardiography and cardiac-CT 3 months after surgery. We measured length of the LV in parasternal long axis view, and both systolic and diastolic LV areas in parasternal short axis views at the level of mitral valve, papillary muscles and apex. Volumes and EF of the LV were calculated using Simpson's method of discs (tri-plane area) or Cylinder-hemiellipsoid method (single plane area).Results: The pigs with coronary occlusion had anterior MI scars and reduced EF (average EF 42 ± 10%) by CT. Measurements of LV volumes and EF were reproducible by echocardiography. Compared with CT, end-diastolic volume (EDV) measured by echocardiography showed good correlation and agreement using either Simpson's method (r = 0.90; mean difference -2, 95% CI -47 to 43 mL) or Cylinder-hemiellipsoid method (r = 0.94; mean difference 3, 95% CI -44 to 49 mL). Furthermore, End-systolic volume (ESV) measured by echocardiography showed also good correlation and agreement using either Simpson's method (r = 0.94; mean difference 12 ml, 95% CI: -16 to 40) or Cylinder-hemiellipsoid method (r = 0.97; mean difference:13 ml, 95% CI: -8 to 33). EF was underestimated using either Simpson's method (r = 0.78; mean difference -6, 95% CI -11 to 1%) or Cylinder-hemiellipsoid method (r = 0.74; mean difference -4, 95% CI-10 to 2%).Conclusion: Our results indicate that measurement of LV volumes may be accurate, but EF is underestimated using either three or single parasternal short axis planes by echocardiography in a large animal model of chronic MI. [ABSTRACT FROM AUTHOR]

Background: Levosimendan is an inotropic agent with cardioprotective and vasodilating properties used for the management of acutely decompensated heart failure. We studied the effects of levosimendan treatment on the size of myocardial infarction (MI) and left ventricular (LV) function in experimental pig model of post MI heart failure.Methods: After occlusion of the left anterior descending (LAD) coronary artery, animals received levosimendan 5 mg/kg/day orally for 8 weeks (n=7) or no treatment (n=18). One week after stopping treatment, transthoracic echocardiography, CT scan and positron emission tomography were performed to evaluate myocardial function, perfusion and oxidative metabolism. Histology was used to confirm the size of MI and features of LV remodelling.Results: The size of MI was significantly smaller in the levosimendan group than in the controls (12±13% vs 27±15% of the LV, p=0.03). End-diastolic volume (EDV) and end-systolic volume (ESV) were smaller in the levosimendan than in the control group (EDV 161±29 mL vs 245±84 mL, p=0.06; ESV 81±18 mL vs 149±67 mL, p=0.03), whereas ejection fraction tended to be higher in the levosimendan group (50±6% vs 41±8%, p=0.06).Conclusions: Eight weeks of levosimendan therapy after recent LAD occlusion decreases the size of MI and leads to better preservation of LV function as well as reduced LV remodelling. [ABSTRACT FROM AUTHOR]