May 10, 2013Journal of Applied Physiology20 citationsOpen Access

Acute right ventricular pressure overload compromises left ventricular function by altering septal strain and rotation

Q: What is the clinical evidence from this study?

Study design: Other. Population: Acute right ventricular pressure overload (n=7). Intervention: Acute right ventricular pressure overload via pulmonary artery banding vs. Baseline. Primary outcome: Septal radial strain on the right ventricular side (p=<0.05).

JCJason ChuaCurtin University WZWei ZhouElectrophysiology JHJonathan K. HoAgriculture and Agri-Food Canada

Key Result

Acute right ventricular pressure overload significantly impaired left ventricular performance by inducing a negative radial strain from 28% to -16% on the right ventricular side of the septum.

Structured PICO

Does acute right ventricular pressure overload impair left ventricular performance by altering septal strain and rotational dynamics in a porcine model?

Population

Seven anesthetized pigs weighing 40-46 kg underwent acute right ventricular pressure overload via pulmonary artery banding to study left ventricular mechanics.

Intervention

Banding of the pulmonary artery to achieve acute right ventricular pressure overload (>50 mmHg)

Comparator

Baseline (prior to banding)

Outcome

Left ventricular performance (end-systolic elastance, dP/dt, end-diastolic volume, cardiac output) and strain/rotational dynamicssurrogate

Acute right ventricular pressure overload impairs left ventricular performance primarily by altering septal strain and apical rotation.

Main Result

Absolute Event Rate: -16% vs 28%

p-value: p=<0.05

Limitations

Assessment of global function based on a single 2D image
Open-chest and open-pericardium pig model may have limited extrapolation to intact humans
Difficulty in obtaining consistently adequate longitudinal views precluded including longitudinal strain in the analysis
Acute timeframe does not capture chronic structural alterations

Abstract

While right ventricular (RV) dysfunction has long been known to affect the performance of left ventricle (LV), the mechanisms remain poorly defined. Recently, speckle-tracking echocardiography has demonstrated that preservation of strain and rotational dynamics is crucial to both LV systolic and diastolic function. We hypothesized that alteration in septal strain and rotational dynamics of the LV occurs during acute RV pressure overload (RVPO) and leads to decreased cardiac performance. Seven anesthetized pigs underwent median sternotomy and placement of intraventricular pressure-volume conductance catheters. Two-dimensional echocardiographic images and LV pressure-volume loops were acquired for offline analysis at baseline and after banding of the pulmonary artery to achieve RVPO (>50 mmHg) induced RV dysfunction. RVPO resulted in a significant decrease (P < 0.05) in LV end-systolic elastance (50%), systolic change in pressure over change in time (19%), end-diastolic volume (22%), and cardiac output (37%) that correlated with decrease in LV global circumferential strain (58%), LV apical rotation (28%), peak untwisting (reverse rotation) rate (27%), and prolonged time to peak rotation (17%), while basal rotation was not significantly altered. RVPO reduced septal radial and circumferential strain, while no other segment of the LV midpapillary wall was affected. RVPO decreased septal radial strain on LV side by 27% and induced a negative radial strain from 28 ± 5 to -16 ± 2% on the RV side of the septum. The septal circumferential strain on both LV and RV side decreased by 46 and 50%, respectively, following RVPO (P < 0.05). Our results suggest that acute RVPO impairs LV performance by primarily altering septal strain and apical rotation.

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