Right ventricular dysfunction

A porcine model for acute ischaemic right ventricular dysfunction

OBJECTIVES

To establish an experimental model for acute ischaemic isolated right ventricular dysfunction and the subsequent haemodynamic changes.

METHODS

An open-chest porcine model with ischaemic dysfunction of the right ventricle induced by ligation of the three main branches supporting the right ventricular free wall. Invasive monitoring of mean arterial blood pressure (MAP), central venous pressure (CVP), left atrial pressure (LAP) and right ventricular pressure (RVP); ultrasonic measurement of cardiac output (CO) and calculation of haemodynamic parameters such as stroke volume (SV), systemic vascular resistance (SVR), pulmonary vascular resistance (PVR) and right ventricular stroke work (RVSW) using standard formulae.

RESULTS

The ischaemic challenge to the right ventricle resulted in a significant (≥30%) reduction in RVSW associated with an increase (6-25%) in CVP and reduction (8-18%) in pulmonary artery pressure (PAP) despite unchanged PVR, all reflecting the failing right ventricle. There was also a significant drop in CO (14-22%) despite unchanged LAP indicating lessened transpulmonary delivery of left ventricular preload due to the failing right ventricle causing the haemodynamic compromise rather than left ventricular failure. Supraventricular and ventricular arrhythmias occurred in three and two out of seven pigs, respectively-all of which except one were successfully resuscitated with cardioversion and/or defibrillation.

CONCLUSIONS

This novel open-chest porcine model of induced ischaemia of the right ventricular free wall resulted in significant haemodynamic compromise confirmed using standard haemodynamic measurements making it useful for further research on acute, ischaemic isolated right ventricular failure.

Right side of heart failure

The function of the right ventricle (RV) in heart failure (HF) has been mostly ignored until recently. A 2006 report of the National Heart, Lung, and Blood Institute identified a gap between RV research efforts and its clinical importance compared with that of the left ventricle. This recent shift in paradigm is fueled by the prognostic value ascribed to RV failure in HF and morbidity/mortality after myocardial infarction and surgery. In this review, we examine the significance of RV failure in the HF setting, its clinical presentation and pathophysiology, and ways to evaluate RV function using echocardiographic measurements. Furthermore, we discuss the medical management of RV failure including traditional therapies like beta-blockers and newer options like nitric oxide, phosphodiesterase inhibitors, and calcium sensitizers. Mechanical support is also examined. Finally, this review places an emphasis on RV failure in the setting of left ventricular assist devices and heart transplantation.

Incidence and prognostic value of right ventricular failure in acute respiratory distress syndrome

OBJECTIVE

To analyse the incidence and the impact on outcome of right ventricular failure (RVF) in patients with acute respiratory distress syndrome (ARDS).

PATIENTS AND METHODS

A total of 145 ARDS patients included in the previously published French Pulmonary Artery Catheter (PAC) study were randomly assigned to receive a PAC. All patients were ventilated according to a strategy aimed at limiting plateau pressure. The RVF was defined by the concomitant presence of: (1) a mean pulmonary artery pressure (MPAP) > 25 mmHg, (2) a central venous pressure (CVP) higher than pulmonary artery occlusion pressure (PAOP) and (3) a stroke volume index < 30 mL m(-2).

RESULTS

Right ventricular failure was present in 9.6% of patients. Mortality was 68% at day-90 with no difference between patients with RVF (RVF+) and without RVF (71 vs. 67%, respectively). SAPS II, PaO(2)/FiO(2) and PaCO(2) were similar in both groups. Tidal volume and I/E ratio were significantly higher in RVF+ (9.7 +/- 2.8 vs. 8.6 +/- 1.8 ml m(-2) and 0.7 +/- 0.5 vs. 0.5 +/- 0.2). Plateau pressure tended to be higher in RVF+ (28 +/- 6 vs. 25 +/- 6 cmH(2)O, NS). In multivariate analysis, PaO(2)/FiO(2), mean arterial pressure, arterial pH, SvO(2), MPAP and presence of CVP > PAOP, but not RVF, were independently associated with day-90 mortality.

CONCLUSION

In this group of patients investigated early in the course of ARDS and ventilated according to a strategy aimed at limiting plateau pressure, the presence of RVF was about 10%. Unlike MPAP and the presence of CVP > PAOP, RVF at this early stage did not appear as an independent factor of mortality.