Cardiac output assessment methods in left ventricular assist device patients: A problem of heteroscedasticity

Severe Early Graft Dysfunction Post-Heart Transplantation: Two Clinical Trajectories and Diastolic Perfusion Pressure as a Predictor of Mechanical Circulatory Support

BACKGROUND

Severe early graft dysfunction (EGD) is defined by mechanical circulatory support (MCS) <24 hours of heart transplantation (HT). We classified severe EGD based on timing of post-HT MCS: 'Immediate' intra-operative vs 'Delayed' post-operative MCS (after admission into intensive care unit (ICU) from operating theatre). We hypothesised that (i) risk factors and clinical course differ between 'Immediate' and 'Delayed' MCS; and (ii) diastolic perfusion pressure (DPP=diastolic blood pressure-central venous pressure) and Norepinephrine equivalents (NE=sum of vasopressor doses), as measures of vasoplegia are related to 'Delayed' MCS.

METHODS

Two-centre study of 216 consecutive patients who underwent HT. Recipient, donor, vasopressor doses and hemodynamic data at T0 and T6 (on admission and 6 hours after admission into ICU) were collected.

RESULTS

Of the 216 patients, 67 patients had severe EGD ('Immediate' MCS: n=43, 'Delayed' MCS: n=24). The likelihood of 'immediate' MCS but not 'delayed' MCS increased with increasing warm ischemic and cardiopulmonary bypass times on multinomial regression analysis with 'no MCS' as the referent group. One-year mortality was highest in 'Immediate' MCS vs 'no MCS' and 'delayed' MCS (34.9% vs 3.4% and 8% respectively, P<0.001). Of the patients who had no immediate post-transplant MCS, DPP and NE at T6 were independently associated with subsequent 'delayed' MCS'. Sensitivity and specificity of NE ≥0.2mcg/kg/min for 'Delayed' MCS were 71% and 81%. Sensitivity and specificity of DPP of ≥40mmHg for No MCS were 83% and 74%. The discriminatory value of systemic vascular resistance for 'Delayed' MCS was poor.

CONCLUSION

Risk factors and one-year survival differed significantly between 'Immediate' and 'Delayed' post-HT MCS. The latter is related to lower DPP and higher NE, which is consistent with vasoplegia as the dominant pathophysiology.

Value of Invasive Hemodynamic Assessments in Patients Supported by Continuous-Flow Left Ventricular Assist Devices

Left ventricular assist devices (LVADs) are increasingly used in patients with end-stage heart failure (HF). There is a significant risk of HF admissions and hemocompatibility-related adverse events that can be minimized by optimizing the LVAD support. Invasive hemodynamic assessment, which is currently underutilized, allows personalization of care for patients with LVAD, and may decrease the need for recurrent hospitalizations. It also aids in triaging patients with persistent low-flow alarms, evaluating reversal of pulmonary vasculature remodeling, and assessing right ventricular function. In addition, it can assist in determining the precipitant for residual HF symptoms and physical limitation during exercise and is the cornerstone of the assessment of myocardial recovery. This review provides a comprehensive approach to the use of invasive hemodynamic assessments in patients supported with LVADs.

Standardization of the Right Heart Catheterization and the Emerging Role of Advanced Hemodynamics in Heart Failure

The accurate assessment of hemodynamics is paramount to providing timely and efficacious care for patients presenting in cardiogenic shock. Recently, the regular use of the pulmonary artery catheter in cardiogenic shock has had a resurgence with emerging data indicating improved survival in the modern era. Optimal multidisciplinary management of advanced heart failure and cardiogenic shock relies on our ability to effectively communicate and understand the complete hemodynamic assessment. Standardization of data acquisition and a renewed focus on the physiological processes, and thresholds driving disease progression, including the coupling ratio and myocardial reserve, are needed to fully understand and interpret the hemodynamic assessment. This State-of-the-Art review discusses best practices in the cardiac catheterization laboratory as well as emerging data on the prognostic role of emerging advanced hemodynamic parameters.