Angiotensin II in Patients With Shock on Mechanical Circulatory Support: A Single-Center Retrospective Case Series

Vasoplegia in Heart, Lung, or Liver Transplantation: A Narrative Review

Vasoplegia is a pathophysiologic state of hypotension in the setting of normal or high cardiac output and low systemic vascular resistance despite euvolemia and high-dose vasoconstrictors. Vasoplegia in heart, lung, or liver transplantation is of particular interest because it is common (approximately 29%, 28%, and 11%, respectively), is associated with adverse outcomes, and because the agents used to treat vasoplegia can affect immunosuppressive and other drug metabolism. This narrative review discusses the pathophysiology, risk factors, and treatment of vasoplegia in patients undergoing heart, lung, and liver transplantation. Vasoplegia in this patient population is associated with acute kidney injury, hospital length of stay, and even survival. The mechanisms of vasoplegia in this patient population likely involve multiple pathways, including nitric oxide synthase, cyclic guanylate cyclase, cytokine release, hydrogen sulfide, adrenal axis abnormalities, and vasopressin deficiency. Contributors to vasoplegia in this population include mechanical circulatory support such as extracorporeal membrane oxygenation and cardiopulmonary bypass, organ ischemia time, preexisting infection, and medications such as angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and excessive sedation. Treatment of vasoplegia in this population begins with conventional catecholamines and vasopressin analogs. Occasionally, agents, including methylene blue, hydroxocobalamin, and angiotensin II, are administered. Though retrospective literature suggests a hemodynamic response to these agents in the transplant population, minimal evidence is available to guide management. In what follows, we discuss the treatment of vasoplegia in the heart, lung, and liver transplant populations based on patient characteristics and potential risk factors associated with non-catecholamine agents.

The Efficacy and Safety of Angiotensin II for Treatment of Vasoplegia in Critically Ill Patients: A Systematic Review

OBJECTIVES

To summarize evidence regarding intravenous angiotensin II administration in critical illness and provide an updated understanding of its effects on various organ dysfunction and renin-angiotensin system (RAS) biomarkers.

DESIGN

A systematic review.

SETTING

A search of PubMed, Embase, and the Cochrane Library from inception to May 3, 2024. Randomized controlled trials (RCTs), nonrandomized trials, quasi-randomized trials, observational studies, case reports, and case series were included. Comparative studies (RCTs and observational studies with comparator) were used for the main analysis.

PARTICIPANTS

Critically ill adults and children.

INTERVENTIONS

Intravenous angiotensin II administration.

MEASUREMENTS AND MAIN RESULTS

Fifty-nine studies with a total of 2,918 participants (5 RCTs, 15 observational studies, and 39 case reports or case series) were analyzed. Septic shock and cardiac surgery were the most common clinical conditions (14 studies for each). In 14 comparative studies (5 RCTs and 9 observational studies), mortality was not different from that in controls, except in 1 observational study. Several studies reported decreased renal replacement therapy use, improved oxygenation and blood pressure response, and decreased rate of myocardial injury with angiotensin II therapy. There was no increase in thrombotic events or adverse events. Angiotensin II therapy reduced renin and angiotensin I levels without affecting other RAS biomarkers.

CONCLUSIONS

Intravenous angiotensin II has been reported in almost 3000 critically ill patients with diverse types of shock. Despite unclear mortality impacts, angiotensin II seems to confer beneficial effects on several organ systems and RAS derangements, without increasing adverse events.

Pathophysiologic Vasodilation in Cardiogenic Shock and Its Impact on Mortality

BACKGROUND

Cardiogenic shock (CS) mortality remains near 40%. In addition to inadequate cardiac output, patients with severe CS may exhibit vasodilation. We aimed to examine the prevalence and consequences of vasodilation in CS.

METHODS

We analyzed all patients hospitalized at a CS referral center who were diagnosed with CS stages B to E and did not have concurrent sepsis or recent cardiac surgery. Vasodilation was defined by lower systemic vascular resistance (SVR), higher norepinephrine equivalent dose, or a blunted SVR response to pressors. Threshold SVR values were determined by their relation to 14-day mortality in spline models. The primary outcome was death within 14 days of CS onset in multivariable-adjusted Cox models.

RESULTS

This study included 713 patients with a mean age of 60 years and 27% females; 14-day mortality was 28%, and 38% were vasodilated. The median SVR was 1308 dynes•s•cm-5 (interquartile range, 870-1652), median norepinephrine equivalent was 0.11 µg/kg per minute (interquartile range, 0-0.2), and 28% had a blunted pressor response. Each 100-dynes•s•cm-5 decrease in SVR below 800 was associated with 20% higher mortality (adjusted hazard ratio, 1.23; P=0.004). Each 0.1-µg/kg per minute increase in norepinephrine equivalent dose was associated with 15% higher mortality (adjusted hazard ratio, 1.12; P<0.001). A blunted pressor response was associated with a nearly 2-fold mortality increase (adjusted hazard ratio, 1.74; P=0.003).

CONCLUSIONS

Pathophysiologic vasodilation is prevalent in CS and independently associated with an increased risk of death. CS vasodilation can be identified by SVR <800 dynes•s•cm-5, high doses of pressors, or a blunted SVR response to pressors. Additional studies exploring mechanisms and treatments for CS vasodilation are needed.

Diagnosis and Management of Vasoplegia in Temporary Mechanical Circulatory Support: A Narrative Review

Refractory vasodilatory shock, or vasoplegia, is a pathophysiologic state observed in the intensive care unit and operating room in patients with a variety of primary diagnoses. Definitions of vasoplegia vary by source but are qualitatively defined clinically as a normal or high cardiac index and low systemic vascular resistance causing hypotension despite high-dose vasopressors in the setting of euvolemia. This definition can be difficult to apply to patients undergoing mechanical circulatory support (MCS). A large body of mostly retrospective literature exists on vasoplegia in the non-MCS population, but the increased use of temporary MCS justifies an examination of vasoplegia in this population. MCS, particularly extracorporeal membrane oxygenation, adds complexity to the diagnosis and management of vasoplegia due to challenges in determining cardiac output (or total blood flow), lack of clarity on appropriate dosing of noncatecholamine interventions, increased thrombosis risk, the difficulty in determining the endpoints of adequate volume resuscitation, and the unclear effects of rescue agents (methylene blue, hydroxocobalamin, and angiotensin II) on MCS device monitoring and function. Care teams must combine data from invasive and noninvasive sources to diagnose vasoplegia in this population. In this narrative review, the available literature is surveyed to provide guidance on the diagnosis and management of vasoplegia in the temporary MCS population, with a focus on noncatecholamine treatments and special considerations for patients supported by extracorporeal membrane oxygenation, transvalvular heart pumps, and other ventricular assist devices.

Management of Vasoplegic Shock in the Cardiovascular Intensive Care Unit after Cardiac Surgery

Vasoplegic shock after cardiac surgery is characterized by hypotension, a high cardiac output, and vasodilation. Much of the understanding of this pathologic state is informed by the understanding of septic shock. Adverse outcomes and mortality are increased with vasoplegic shock. Early recognition and a systematic approach to its management are critical. The need for vasopressors to sustain an adequate blood pressure as well as pharmacologic adjuncts to mitigate the inflammatory inciting process are necessary. The rationale behind vasopressor escalation and consideration of adjuncts are discussed.

Efficacy and safety of angiotensin II in cardiogenic shock: A systematic review

BACKGROUND

Cardiogenic shock (CS) is associated with high morbidity and mortality. In recent times, there is increasing interest in the role of angiotensin II in CS. We sought to systematically review the current literature on the use of angiotensin II in CS.

METHODS

PubMed, EMBASE, Medline, Web of Science, PubMed Central, and CINAHL databases were systematically searched for studies that evaluated the efficacy of angiotensin II in patients with CS during 01/01/2010-07/07/2022. Outcomes of interest included change in mean arterial pressure (MAP), vasoactive medication requirements (percent change in norepinephrine equivalent [NEE] dose), all-cause mortality, and adverse events.

RESULTS

Of the total 2,402 search results, 15 studies comprising 195 patients were included of which 156 (80%) received angiotensin II. Eleven patients (84.6%) in case reports and case series with reported MAP data at hour 12 noted an increase in MAP. Two studies noted a positive hemodynamic response (defined a priori) in eight (88.9%) and five (35.7%) patients. Eight studies reported a reduction in NEE dose at hour 12 after angiotensin II administration and one study noted a 100% reduction in NEE dose. Out of 47 patients with documented information, 13 patients had adverse outcomes which included hepatic injury (2), digital ischemia (1), ischemic optic neuropathy (1), ischemic colitis (2), agitated delirium (1), and thrombotic events (2).

CONCLUSIONS

In this first systematic review of angiotensin II in CS, we note the early clinical experience. Angiotensin II was associated with improvements in MAP, decrease in vasopressor requirements, and minimal reported adverse events.

Angiotensin II for Vasodilatory Hypotension in Patients Requiring Mechanical Circulatory Support

Background: Patients supported on mechanical circulatory support devices experience vasodilatory hypotension due to high surface area exposure to nonbiological and non-endothelialized surfaces. Angiotensin II has been studied in general settings of vasodilatory shock, however concerns exist regarding the use of this vasopressor in patients with pre-existing cardiac failure. The objective of this study was to assess the systemic and central hemodynamic effects of angiotensin II in patients with primary cardiac or respiratory failure requiring treatment with mechanical circulatory support devices. Methods: Multicenter retrospective observational study of adults supported on a mechanical circulatory support device who received angiotensin II for vasodilatory shock. The primary outcome was the intraindividual change from baseline in mean arterial pressure (MAP) and vasopressor dosage after angiotensin II. Results: Fifty patients were included with mechanical circulatory devices that were primarily used for cardiac failure (n = 41) or respiratory failure (n = 9). At angiotensin II initiation, the norepinephrine equivalent vasopressor dosage was 0.44 (0.34, 0.64) and 0.47 (0.33, 0.73) mcg/kg/min in the cardiac and respiratory groups, respectively. In the cardiac group, MAP increased from 60 to 70 mmHg (intraindividual P < .001) in the 1 h after angiotensin II initiation and the vasopressor dosage declined by 0.04 mcg/kg/min (intraindividual P < .001). By 12 h, the vasopressor dosage declined by 0.16 mcg/kg/min ( P = .001). There were no significant changes in cardiac index or mean pulmonary artery pressure throughout the 12 h following angiotensin II. In the respiratory group, similar but nonsignificant effects at 1 h on MAP (61-81 mmHg, P = .26) and vasopressor dosage (decline by 0.13 mcg/kg/min, P = .06) were observed. Conclusions: In patients requiring mechanical circulatory support for cardiac failure, angiotensin II produced beneficial systemic hemodynamic effects without negatively impacting cardiac function or pulmonary pressures. The systemic hemodynamic effects in those with respiratory failure were nonsignificant due to limited sample size.