Myocardial function reclassification: Echocardiographic strain patterns in patients with chronic Chagas cardiomyopathy and intraventricular dyssynchrony.

BACKGROUND: We aimed to identify, among Chronic Chagas Cardiomyopathy (CCC) patients with left ventricular dysfunction (LVD) and non-left bundle branch block (non-LBBB), subgroups with different functional and mechanical patterns of global longitudinal strain (GLS) and intraventricular dyssynchrony (IVD) at rest and after exercise stress test, and reclassify them using a new echocardiographic approach. METHODOLOGY: In this single-center cross-sectional study, 40 patients with CCC, left ventricular ejection fraction (LVEF) ≤ 35% and non-LBBB underwent rest echocardiography and then treadmill exercise stress echocardiography with GLS and IVD analysis. The sample was divided into four groups, based on GLS and IVD significant variation between rest and exercise: GLS + IVD+ (9 patients); GLS + IVD- (9 patients); GLS-IVD+ (10 patients); GLS-IVD- (10 patients). RESULTS: At rest, median LVEF was 28% (21.3%-33%) and GLS (-7% (-5%/-9.3%), were not different among groups. The average response of GLS was an increase of 0.74% over rest values, and the average response of IVD was a decrease of 6.9 ms. Group GLS-IVD+ presented more dyssynchrony at rest (p = 0.01). Left atrial (LA) volume (higher in GLS-IVD-) (p = 0.022) and TAPSE (higher in GLS + IVD+) (p = 0.015) were also different among groups at baseline. Of the 40 patients evaluated, 27 (67.5%) had very severe LVD (GLS < -8%). In addition, among these patients, 11 patients had contractile reserve after undergoing stress echocardiography. CONCLUSIONS: In patients with CCC, severe LVD and non-LBBB, the evaluation of GLS and IVD between rest and exercise was able to reclassify myocardial function and to identify subgroups with contractile reserve and significant dyssynchronopathy.

Preliminary evidence of age-dependent clinical signs associated with porcine circovirus 2b in experimentally infected CH3/Rockefeller mice.

Mice and rats are susceptible to porcine circovirus 2b (PCV2) infection under field and experimental conditions. However, whether PCV2 induces disease in rodents remains a matter of debate. The objectives of the present study were to determine whether PCV2-induced disease in mice is age-dependent and whether intranasally inoculated animals are able to infect animals they come into contact with. Twenty-five CH3/Rockefeller mice were divided into six groups and intranasally inoculated with 25µL of either PCV2b or PBS on days 0, 3 and 6. One group remained untreated. Two age groups were tested: 3-week-old mice and 6-week-old mice. The administration of three PCV2 intranasal inoculations at intervals of three days was able to induce infection and support virus transmission in susceptible mice, regardless of the age at inoculation. The clinical signs associated with PCV2 infection were more severe in younger mice, and PCV2-DNA load was higher in their faeces. In conclusion, PCV2 induced disease in mice.