Novel Use for Intracardiac Echocardiography

The role of innovative modeling and imaging techniques in improving outcomes in patients with LVAD

Heart failure remains a significant cause of mortality in the United States and around the world. While organ transplantation is acknowledged as the gold standard treatment for end stage heart failure, supply is limited, and many patients are treated with left ventricular assist devices (LVADs). LVADs extend and improve patients' lives, but they are not without their own complications, particularly the hemocompatibility related adverse events (HRAE) including stroke, bleeding and pump thrombosis. Mainstream imaging techniques currently in use to assess appropriate device function and troubleshoot complications, such as echocardiography and cardiac computed tomography, provide some insight but do not provide a holistic understanding of pump induced flow alterations that leads to HRAEs. In contrast, there are technologies restricted to the benchtop-such as computational fluid dynamics and mock circulatory loops paired with methods like particle image velocimetry-that can assess flow metrics but have not been optimized for clinical care. In this review, we outline the potential role and current limitations of converging available technologies to produce novel imaging techniques, and the potential utility in evaluating hemodynamic flow to determine whether LVAD patients may be at higher risk of HRAEs. This addition to diagnostic and monitoring capabilities could improve prevention and treatment of LVAD-induced complications in heart failure patients.

Intracardiac echocardiography Chinese expert consensus

In recent years, percutaneous catheter interventions have continuously evolved, becoming an essential strategy for interventional diagnosis and treatment of many structural heart diseases and arrhythmias. Along with the increasing complexity of cardiac interventions comes ever more complex demands for intraoperative imaging. Intracardiac echocardiography (ICE) is well-suited for these requirements with real-time imaging, real-time monitoring for intraoperative complications, and a well-tolerated procedure. As a result, ICE is increasingly used many types of cardiac interventions. Given the lack of relevant guidelines at home and abroad and to promote and standardize the clinical applications of ICE, the members of this panel extensively evaluated relevant research findings, and they developed this consensus document after discussions and correlation with front-line clinical work experience, aiming to provide guidance for clinicians and to further improve interventional cardiovascular diagnosis and treatment procedures.

Physiology of Continuous-Flow Left Ventricular Assist Device Therapy

The expanding use of continuous-flow left ventricular assist devices (CF-LVADs) for end-stage heart failure warrants familiarity with the physiologic interaction of the device with the native circulation. Contemporary devices utilize predominantly centrifugal flow and, to a lesser extent, axial flow rotors that vary with respect to their intrinsic flow characteristics. Flow can be manipulated with adjustments to preload and afterload as in the native heart, and ascertainment of the predicted effects is provided by differential pressure-flow (H-Q) curves or loops. Valvular heart disease, especially aortic regurgitation, may significantly affect adequacy of mechanical support. In contrast, atrioventricular and ventriculoventricular timing is of less certain significance. Although beneficial effects of device therapy are typically seen due to enhanced distal perfusion, unloading of the left ventricle and atrium, and amelioration of secondary pulmonary hypertension, negative effects of CF-LVAD therapy on right ventricular filling and function, through right-sided loading and septal interaction, can make optimization challenging. Additionally, a lack of pulsatile energy provided by CF-LVAD therapy has physiologic consequences for end-organ function and may be responsible for a series of adverse effects. Rheological effects of intravascular pumps, especially shear stress exposure, result in platelet activation and hemolysis, which may result in both thrombotic and hemorrhagic consequences. Development of novel solutions for untoward device-circulatory interactions will facilitate hemodynamic support while mitigating adverse events. © 2021 American Physiological Society. Compr Physiol 12:1-37, 2021.

Use of Intracardiac Echocardiography to Evaluate Continuous-Flow Left Ventricular Assist Device Function in a Man With Obesity

Aortic insufficiency with recirculation can be difficult to diagnose echocardiographically in patients who have continuous-flow left ventricular assist devices. Transthoracic and transesophageal echocardiography can underestimate its severity; moreover, transesophageal echocardiography necessitates general anesthesia. We report the case of a 58-year-old man with obesity and end-stage nonischemic cardiomyopathy who, after 3 months of support with a continuous-flow left ventricular assist device, underwent intracardiac echocardiography to evaluate complications potentially associated with the device. The findings ruled out aortic insufficiency, preventing an unnecessary valvular intervention.

Inadequate left ventricular unloading during ramp is associated with hospitalization or death during left ventricular assist device support

A combined right and left-sided heart catheterization (RHC/LHC) protocol was recently reported to optimize patients supported by left ventricular assist device (LVAD). Using this platform, we sought to evaluate the prognostic significance of several hemodynamic indices, including left ventricular end-diastolic pressure (LVEDP) and transaortic gradient (peak aortic pressure - peak left ventricular pressure in systole, TAG). We evaluated all patients undergoing RHC/LHC at our institution from 2015 through 2018, and comprehensive clinical data were obtained. Primary end points were (1) a composite outcome that included hospitalization or death and (2) 1-year overall survival after catheterization. Forty-two patients were included in the analysis. Optimization resulted in normalization of hemodynamic parameters; all variables were significantly improved from baseline (P ≤ .05). On univariate modeling, final LVEDP was associated with the primary end point (hazard ratio [HR], 1.2 per 1-mm Hg increase; 95% CI, 1.1-1.3; P = .002). After adjusting for LVAD speed, TAG, and cardiac index in a multivariate model, the association between LVEDP and the composite end point remained significant (HR, 1.2 per 1-mm Hg increase; 95% CI, 1.1-1.4; P = .001). In the setting of LVAD support, inadequate LV unloading was a significant marker of poor outcomes with time, suggesting that LVEDP is a central prognostic marker in this population.