engleski

Acute cardiac remodeling in short term acute afterload increase - the effect of pericardial constraint.

Aim: As acute short-lived increase in afterload may be a contributory mechanism to sudden death we studied an acute 30% systolic pressure increase (SBPI) in a closed chest, closed pericardium porcine model, closed pericardium being essential to the model clinical applicability. Methods: Seven pigs were studied. All had an acute 5 beat 30% SBPI induced by a non-occlusive mid-desc aortic balloon inflation and release. Each challenge was continuously monitored for changes in cardiac morphology and function by cardiac ultrasound (2D, Doppler and Strain) and changes correlated with pressure data from 3 Millar catheters (LV/Ao ; LA ; RV/RA). Continuous 12 lead ECG and intracardiac electrograms were also recorded. Results: Balloon inflation caused an acute diastolic pressure increase in all cavities (except pulmonary artery) (early diastolic preceeding late changes) a corresponding systolic increase in LV, LA and RA pressures. Acute LV dilatation resulted in pericardial flattening (= pericardial constraint), a right septal shift and a decrease in RV size with a 30% reduction in LVEF % (Fig1a). During inflation, pericardial excursion flattened > 40% in basal, mid and apical LV segments, mostly mid wall (from 3.4±1.4 mm to 1.6±0.7 mm) (Fig 1b). With balloon deflation, all parameters rapidly returned to baseline. Conclusion: Acute afterload increase induced immediate, profound and consistent changes in LV dimensions and function. Pericardial constraint caused marked rightward septal shift which altered right heart diastolic function and reduced filling. Acute loading markedly altered both systolic and diastolic function for both the right and left heart. It remains to be evaluated how these changes affect mechano-electric coupling and as such could play a role in fatal arrhythmias.

Acute afterload; pressure increase; animal model; pericardial flattening.

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