Medical and Mechanical Circulatory Support of the Failing Right Ventricle

PURPOSE OF REVIEW

To describe medical therapies and mechanical circulatory support devices used in the treatment of acute right ventricular failure.

RECENT FINDINGS

Experts have proposed several algorithms providing a stepwise approach to medical optimization of acute right ventricular failure including tailored volume administration, ideal vasopressor selection to support coronary perfusion, inotropes to restore contractility, and pulmonary vasodilators to improve afterload. Studies have investigated various percutaneous and surgically implanted right ventricular assist devices in several clinical settings. The initial management of acute right ventricular failure is often guided by invasive hemodynamic data tracking parameters of circulatory function with the use of pharmacologic therapies. Percutaneous microaxial and centrifugal extracorporeal pumps bypass the failing RV and support circulatory function in severe cases of right ventricular failure.

Prognostic significance of haemodynamic parameters in patients with cardiogenic shock

AIMS

Invasive haemodynamic assessment with a pulmonary artery catheter is often used to guide the management of patients with cardiogenic shock (CS) and may provide important prognostic information. We aimed to assess prognostic associations and relationships to end-organ dysfunction of presenting haemodynamic parameters in CS.

METHODS AND RESULTS

The Critical Care Cardiology Trials Network is an investigator-initiated multicenter registry of cardiac intensive care units (CICUs) in North America coordinated by the TIMI Study Group. Patients with CS (2018-2022) who underwent invasive haemodynamic assessment within 24 h of CICU admission were included. Associations of haemodynamic parameters with in-hospital mortality were assessed using logistic regression, and associations with presenting serum lactate were assessed using least squares means regression. Sensitivity analyses were performed excluding patients on temporary mechanical circulatory support and adjusted for vasoactive-inotropic score. Among the 3603 admissions with CS, 1473 had haemodynamic data collected within 24 h of CICU admission. The median cardiac index was 1.9 (25th-75th percentile, 1.6-2.4) L/min/m2 and mean arterial pressure (MAP) was 74 (66-86) mmHg. Parameters associated with mortality included low MAP, low systolic blood pressure, low systemic vascular resistance, elevated right atrial pressure (RAP), elevated RAP/pulmonary capillary wedge pressure ratio, and low pulmonary artery pulsatility index. These associations were generally consistent when controlling for the intensity of background pharmacologic and mechanical haemodynamic support. These parameters were also associated with higher presenting serum lactate.

CONCLUSION

In a contemporary CS population, presenting haemodynamic parameters reflecting decreased systemic arterial tone and right ventricular dysfunction are associated with adverse outcomes and systemic hypoperfusion.

Hemodynamic effects of COVID-19 vaccination in hospitalized patients awaiting heart transplantation

Background

The hemodynamic effects of pre-transplant vaccination against COVID-19 among heart transplant candidates hospitalized for advanced heart failure remains unknown.

Methods

A retrospective chart review was conducted at a high-volume transplant center from January through December 2021. 22 COVID-19 vaccination events occurred among patients hospitalized for decompensated heart failure while awaiting transplantation. Primary outcomes included inotrope and vasopressor dosages. Secondary outcomes included vital signs, pulmonary artery catheter measurements, diuretic dosages, and renal function. Data were extracted 24 h before through 72 h after vaccination.

Results

One of 22 vaccination events was associated with hemodynamic changes requiring increased inotropic and vasopressor support post-vaccination. In all other cases, transient hemodynamic changes occurred without need for escalated therapy.

Conclusions

COVID-19 vaccination can be administered safely to most critically ill patients with advanced heart failure including those awaiting transplantation. All patients should be monitored closely as some may be susceptible to significant hemodynamic changes.

Challenges in the development and implementation of a healthcare system based extracorporeal cardiopulmonary resuscitation (ECPR) program for the treatment of out of hospital cardiac arrest

INTRODUCTION

Extracorporeal cardiopulmonary resuscitation (ECPR) can treat cardiac arrest refractory to conventional therapies. Many institutions are interested in developing their own ECPR program. However, there may be challenges in logistics and implementation.

AIMS

The aim of our protocol was to demonstrate that an ECPR team was feasible within our healthcare system and that the identification of UPMC Presbyterian as a receiving center allowed for successful treatment within 30 min from EMS dispatch.

METHODS

We developed out of hospital cardiac arrest (OHCA) ECPR protocols for Emergency Medical Services (EMS), EMS communications, and our in-hospital ECPR team. Inclusion criteria indentified patients with a potentially reversible arrest etiology and high probability of recoverable brain injury using a simple checklist: witnessed collapse, layperson CPR, initial shockable rhythm, and age 18-60 years. We trained local EMS crews to screen patients and reviewed the criteria with a Medic Command Physician prior to transport to our hospital.

RESULTS

From October 2015 to March 31st 2018, EMS treated 1165 EMS OHCA cases, transported 664 (57%) to a local hospital, and transported 120 (10%) to our institution. Of these, five (4.1%) patients underwent ECPR. Among excluded cases, 64 (53%) had nonshockable rhythms, 48 (40%) were unwitnessed arrests, 50 (42%) were over age 60 and the remaining 20 (17%) had no documented reasons for exclusion. For ECPR cases, median pre-hospital CPR duration was 26 [IQR 25-40] min. Four patients (80%) received mechanical CPR. Interval from arrest to arrival on scene was 5 [IQR 4-6] min and interval from radio call to activation of ECPR was 13 [IQR 7-21] min. Interval from EMS dispatch to departure from scene was 20 [IQR 19-21] min. Time from EMS dispatch to initiation of ECPR was 63 [IQR 59-69] min.

CONCLUSIONS

ECPR is an infrequent occurrence in EMS practice. Most apparently eligible patients did not get ECPR, highlighting the need for ongoing programmatic development, provider education, and qualitative work exploring barriers to implementation.

The Use of ECMO for the Treatment of Refractory Cardiac Arrest or Postarrest Cardiogenic Shock Following In-Hospital Cardiac Arrest: A 10-Year Experience

OBJECTIVES

Extracorporeal membrane oxygenation (ECMO) has been increasingly used in the treatment of refractory cardiac arrest (extracorporeal cardiopulmonary resuscitation [ECPR]) and postarrest cardiogenic shock (PACS). Our primary objective was to determine the 1-year survival of patients who were treated with ECMO for PACS or in ECPR.

METHODS

We conducted a retrospective analysis of hospitalized patients in a tertiary care facility who underwent treatment with ECMO for ECPR or PACS. Between January 2004 and December 2013, patients were prospectively entered into an institutional registry. One-year follow-up was assessed by electronic medical record or social security death index if clinical follow-up was unavailable.

RESULTS

Fifty-one patients were treated with ECMO during the study period. The mean age was 54.0 ± 10.9 years; the majority of patients were men (80.4%). The most common etiology of arrest was acute myocardial infarction (51.0%). Overall, 13 (25.4%) patients survived for at least 1 year. Preexisting coronary artery disease, hypertension, and hyperlipidemia were associated with reduced likelihood of survival. We observed a significant improvement in 1-year mortality in patients treated for PACS when compared to ECPR, 46.7% versus 16.7%, respectively.

CONCLUSION

The use of ECMO for treatment of refractory cardiac arrest or cardiogenic shock may be a suitable treatment in a very select cohort of patients. Our results support a significantly higher 1-year survival in patients with PACS compared to refractory cardiac arrest.

Echo-Doppler determinants of outcomes in patients with unoperated significant mitral regurgitation in current era

Objective

One-half of patients with severe symptomatic mitral regurgitation (MR) do not undergo surgery due to comorbidities. We evaluated prognosticators of outcomes in patients with unoperated significant MR.

Methods

In this observational study, we retrospectively evaluated medical records of 75 consecutive patients with unoperated significant MR.

Results

All-cause mortality was 39% at 5 years. Non-survivors (n=29) versus survivors (n=46) were: older (77±9.8 vs 68±14, p=0.006), had higher New York Heart Association (NYHA) class (2.7±0.8 vs 2.3±0.8, p=0.037), higher brain natriuretic peptide (1157±717 vs 427±502 pg/mL, p=0.024, n=18), more coronary artery disease (61% vs 35%, p=0.031), more frequent left ventricular ejection fraction <50% (20.7% vs 4.3%, p=0.026), more functional MR (41% vs 22%, p=0.069), higher mitral E/E^′ (12.7±4.6 vs 9.8±4, p=0.008), higher pulmonary artery systolic pressure (PASP; 52.6±18.7 vs 36.7±14, p <0.001), more ≥3+ tricuspid regurgitation (28% vs 4%, p=0.005) and more right ventricular dysfunction (26% vs 6%, p=0.035). Significant predictors of 5-year mortality were PASP (p=0.001) and E/E^′ (p=0.011) using multivariate regression analysis.

Conclusions

Patients with unoperated significant MR have high mortality. Elevated PASP and mitral E/E^′ were the most significant predictors of 5-year survival in patients with unoperated significant MR. Current American College of Cardiology (ACC)/American Heart Association (AHA) guidelines provide a limited incorporation of echo-Doppler parameters in the preoperative risk stratification of patients with severe MR.

Glass transition in pure and doped amorphous solid water: An ultrafast microcalorimetry study

Using an ultrafast scanning microcalorimetry apparatus capable of heating rates in excess of 10(5) Ks, we have conducted the first direct measurements of thermodynamic properties of pure and doped amorphous solid water (also referred to as low density amorphous ice) in the temperature range from 120 to 230 K. Ultrafast microcalorimetry experiments show that the heat capacity of pure amorphous solid water (ASW) remains indistinguishable from that of crystalline ice during rapid heating up to a temperature of 205+/-5 K where the ASW undergoes rapid crystallization. Based on these observations, we conclude that the enthalpy relaxation time in pure ASW must be greater than 10(-5) s at 205 K. We argue that this result contradicts the assignment of glass transition temperature to 135 K and that ASW may undergo fragile to strong transition at temperatures greater than 205 K. Unlike pure ASW, we observe an approximately twofold rise in heat capacity of CH3COOH doped ASW at 177+/-5 K. We discuss results of past studies taking into account possible influence of impurities and confinement on physical properties of ASW.

Fast thermal desorption spectroscopy study of morphology and vaporization kinetics of polycrystalline ice films

Fast thermal desorption spectroscopy was used to investigate the vaporization kinetics of thin (50-100 nm) H(2)O(18) and HDO tracer layers from 2-5 microm thick polycrystalline H(2)O(16) ice films at temperatures ranging from -15 to -2 degrees C. The isothermal desorption spectra of tracer species demonstrate two distinct peaks, alpha and beta, which we attribute to the vaporization of H(2)O(18) initially trapped at or near the grain boundaries and in the crystallites of the polycrystalline ice, respectively. We show that the diffusive transport of the H(2)O(18) and HDO tracer molecules in the bulk of the H(2)O(16) film is slow as compared to the film vaporization. Thus, the two peaks in the isothermal spectra are due to unequal vaporization rates of H(2)O(18) from grain boundary grooves and from the crystallites and, therefore, can be used to determine independently the vaporization rate of the single crystal part of the film and rate of thermal etching of the film. Our analysis of the tracer vaporization kinetics demonstrates that the vaporization coefficient of single crystal ice is significantly greater than those predicted by the classical vaporization mechanism at temperatures near ice melting point. We discuss surface morphological dynamics and the bulk transport phenomena in single crystal and polycrystalline ice near 0 degrees C.

The vaporization rate of ice at temperatures near its melting point

The first study of free vaporization kinetics of ice at temperatures near its melting point is reported. The experimental approach employed is based on a unique combination of thermal desorption spectroscopy, microcalorimetry, and time-of-flight mass spectrometry, making it possible to overcome challenges associated with the introduction of volatile solids into a high vacuum environment. Measurements of the vaporization rate of polycrystalline ice demonstrate that the vaporization kinetics deviate dramatically from those predicted by a simple mobile precursor mechanism. The vaporization rate follows Arrhenius behavior from -40 to 0 degrees C with an effective activation energy of 50+/-4 kJ/mol, which is significantly higher than the value predicted by the simple mobile precursor mechanism. Extrapolation of earlier measurements conducted below -40 degrees C yields a value of approximately 0.02 at 0 degrees C for the vaporization coefficient alphav. In contrast, experimentally determined vaporization coefficient is found to be 0.7+/-0.3 and shows a weak dependence on temperature up to the bulk melting point. The role of possible surface phase transitions in the mechanisms of release and uptake of H2O and other chemical species by ice surfaces is discussed.

DNA fingerprinting and phenotyping of Mycobacterium tuberculosis isolates from human immunodeficiency virus (HIV)-seropositive and HIV-seronegative patients in Tanzania

With the purpose of determining whether the risk of infection with a particular clone of Mycobacterium tuberculosis is influenced by the human immunodeficiency virus (HIV) status of the host, we analyzed and compared 68 mycobacterial isolates obtained from HIV-seropositive patients with tuberculosis (TB) in Dar es Salaam, Tanzania, with 66 mycobacterial isolates obtained from HIV-seronegative patients with TB in the same geographical region by using both DNA fingerprinting and classical phenotyping methods. One hundred one different IS6110 fingerprinting patterns were observed in the 134 isolates. The level of diversity of the DNA fingerprints observed in the HIV-seropositive group was comparable to the level of the diversity observed in the HIV-seronegative group. Resistance to a single anti-TB drug was found in 8.8% of the tested isolates, and 3.2% of the isolates were resistant to more than one anti-TB drug. The drug susceptibility profiles were not significantly difference between the two groups of isolates compared in the present study. Phenotypic characteristics which classify M. tuberculosis strains as belonging to the Asian subgroup correlated with a low IS6110 copy number per isolate. However, the occurrence of Asian subgroup strains was not associated with the HIV status of the patients. The results of the study suggested an equal risk of infection with a defined M. tuberculosis clone for HIV-seropositive and HIV-seronegative individuals.