Functional and pathological characteristics of reversible remodeling in a canine right ventricle in response to volume overloading and volume unloading

Crossing Boundaries: Utilizing Left-sided Impella for Right Ventricular Mechanical Support and Intraoperative Transesophageal Echocardiogram Considerations

OBJECTIVE

Right ventricular failure is a leading cause of mortality among patients with various etiologies of cardiogenic shock. This case series outlines an innovative approach to directly unloading the right ventricle with the Impella LD or 5.5 without crossing the tricuspid valve in cases requiring tricuspid valve repair or replacement.

DESIGN

Retrospective single-center review.

SETTING

Single tertiary care university hospital.

PARTICIPANTS

Patients who underwent Impella LD or 5.5 insertions for right ventricular support.

INTERVENTIONS

Impella LD or 5.5 inserted directly into the right ventricle via the pulmonary artery.

MEASUREMENTS AND MAIN RESULTS

Patients' baseline, intraoperative, and immediate postoperative clinical and echocardiographic data were obtained. Of the five consecutive patients with severe preoperative right ventricular failure who underwent surgical tricuspid valve procedures and Impella placement, three of the patients underwent concomitant left heart procedures. The Impella was preemptively inserted before separation from cardiopulmonary bypass in all patients. Four patients were extubated within the first 24 hours and ambulated with the Impella by postoperative day (POD) 3. By POD 10, four patients had sufficient right ventricular recovery to allow for Impella LD explant. One patient died due to septic shock with the right ventricular assist device still in place. One patient was transitioned to comfort measures 29 days after explant of the Impella device.

CONCLUSIONS

Left-sided Impella can be used to support the right ventricle in patients who have undergone surgical tricuspid valve procedures. It provides direct right ventricular unloading, does not cross a newly replaced or repaired tricuspid valve, and allows early ambulation.

Echocardiographic assessment of right ventricular systolic function in healthy Beagle dogs compared to high field cardiac magnetic resonance imaging

Ten healthy Beagle dogs were used to compare selected echocardiographic parameters of right ventricular (RV) systolic function with high field cardiac magnetic resonance imaging (MRI). All dogs underwent complete transthoracic echocardiography before and during anesthesia, as well as cardiac MRI with determination of morphology-based ejection fraction, and phase contrast angiography-derived stroke volume. A correlation analysis was carried out between echocardiographic and MRI parameters. The values of fractional area change, tricuspid annular plane systolic excursion, tissue Doppler imaging derived peak velocity of the isovolumic contraction wave and systolic wave of the lateral tricuspid valve annulus showed lower values under general anesthesia. Of all echocardiographic parameters of RV systolic function, only fractional area change (r = 0.671, P = 0.034) and tissue Doppler imaging derived peak velocity of the systolic wave of the lateral tricuspid valve annulus (r = 0.768; P = 0.01), showed a significant correlation with MRI derived stroke volume. None of the echocardiographic parameters correlated with MRI derived ejection fraction. When evaluating the RV echocardiographically, fractional area change and peak velocity of the systolic wave of the lateral tricuspid valve annulus appear to be the most reliable predictors of RV systolic function when compared to MRI under anesthesia.

Animal Models of Repaired Tetralogy of Fallot: Current Applications and Future Perspectives

Tetralogy of Fallot is the most common cyanotic congenital heart disease. Despite ongoing improvements in the initial surgical repair, there are lingering concerns regarding the long-term outcomes that may be complicated by right ventricular dysfunction, right ventricular dyssynchrony, and sudden cardiac death. The mechanisms leading to these late complications remain incompletely understood. Experimental animal models have been developed as preclinical steps to gain better insight into the pathophysiology of diseases and to develop new therapeutic strategies. This article summarizes the various types of experimental animal models of repaired tetralogy of Fallot published to date in the literature, with the aim of achieving a greater understanding of the deleterious mechanisms that may lead to these known late and sometimes lethal complications. In addition to analysing the type of animals that can be used according to a given study's objectives, needs, and constraints, the present review also evaluates the type of dysfunction that can be reproduced in our model according to the research objectives, as well as the different types of studies in which these models can be used. In view of all that, we propose a decision algorithm to create an animal model of repaired tetralogy of Fallot. This synthesis should furthermore help in the development of future studies and in the design of new experimental models, thus allowing greater insight into this disease, while not forgetting the ultimate goal of broadening future therapeutic measures to reduce the morbidity and mortality of this prevalent congenital heart disease.

Beneficial effects of a cardiac support device on left ventricular remodeling after posterior myocardial infarction: an evaluation by echocardiography, pressure-volume curves and ventricular histology

PURPOSE

Posterior myocardial infarction (MI) can induce LV remodeling and ischemic mitral regurgitation (IMR). The protective effects of a cardiac support device (CSD) against LV remodeling and IMR after posterior MI have been poorly documented.

METHODS

Posterior MI was induced by ligation of the left circumflex coronary artery in beagle dogs. After 7 days, the dogs were randomized to a CSD placement (CSD group, n = 8) or no treatment (CTL group, n = 8).

RESULTS

At 3 months after MI, the LV remodeling was less marked and the LV and RV systolic functions were better in the CSD group than in the CTL group. Neither the RV nor LV diastolic function (min dP/dt, Tau and EDPVR) was disturbed by the CSD. IMR was consistently prevented in our canine model.

CONCLUSION

Early application of a CSD after posterior MI can attenuate LV remodeling without causing any deterioration of the biventricular diastolic function.

Building a bridge to recovery: the pathophysiology of LVAD-induced reverse modeling in heart failure

Heart failure mainly caused by ischemic or dilated cardiomyopathy is a life-threatening disorder worldwide. The previous work in cardiac surgery has led to many excellent surgical techniques for treating cardiac diseases, and these procedures are now able to prolong the human lifespan. However, surgical treatment for end-stage heart failure has been under-explored, although left ventricular assist device (LVAD) implantation and heart transplantation are options to treat the condition. LVAD can provide powerful circulatory support for end-stage heart failure patients and improve the survival and quality of life after implantation compared with the existing medical counterparts. Moreover, LVADs play a crucial role in the "bridge to transplantation", "bridge to recovery" and recently have served as "destination therapy". The structural and molecular changes that improve the cardiac function after LVAD implantation are called "reverse remodeling", which means that patients who have received a LVAD can be weaned from the LVAD with restoration of their cardiac function. This strategy is a desirable alternative to heart transplantation in terms of both the patient quality of life and due to the organ shortage. The mechanism of this bridge to recovery is interesting, and is different from other treatments for heart failure. Bridge to recovery therapy is one of the options in regenerative therapy which only a surgeon can provide. In this review, we pathophysiologically analyze the reverse remodeling phenomenon induced by LVAD and comment about the clinical evidence with regard to its impact on the bridge to recovery.