Hemodynamic effects of inhaled nitric oxide in right ventricular myocardial infarction and cardiogenic shock

Inhaled NO at a crossroads in cardiac surgery: current need to improve mechanistic understanding, clinical trial design and scientific evidence

Inhaled nitric oxide (NO) has been used in pediatric and adult perioperative cardiac intensive care for over three decades. NO is a cellular signaling molecule that induces smooth muscle relaxation in the mammalian vasculature. Inhaled NO has the unique ability to exert its vasodilatory effects in the pulmonary vasculature without any hypotensive side-effects in the systemic circulation. In patients undergoing cardiac surgery, NO has been reported in numerous studies to exert beneficial effects on acutely lowering pulmonary artery pressure and reversing right ventricular dysfunction and/or failure. Yet, various investigations failed to demonstrate significant differences in long-term clinical outcomes. The authors, serving as an advisory board of international experts in the field of inhaled NO within pediatric and adult cardiac surgery, will discuss how the existing scientific evidence can be further improved. We will summarize the basic mechanisms underlying the clinical applications of inhaled NO and how this translates into the mandate for inhaled NO in cardiac surgery. We will move on to the popular use of inhaled NO and will talk about the evidence base of the use of this selective pulmonary vasodilator. This review will elucidate what kind of clinical and biological barriers and gaps in knowledge need to be solved and how this has impacted in the development of clinical trials. The authors will elaborate on how the optimization of inhaled NO therapy, the development of biomarkers to identify the target population and the definition of response can improve the design of future large clinical trials. We will explain why it is mandatory to gain an international consensus for the state of the art of NO therapy far beyond this expert advisory board by including the different major players in the field, such as the different medical societies and the pharma industry to improve our understanding of the real-life effects of inhaled NO in large scale observational studies. The design for future innovative randomized controlled trials on inhaled NO therapy in cardiac surgery, adequately powered and based on enhanced biological phenotyping, will be crucial to eventually provide scientific evidence of its clinical efficacy beyond its beneficial hemodynamic properties.

Severe right ventricular infarction due to iatrogenic aortocoronary dissection successfully treated by surgical repair and extracorporeal membrane oxygenation

Iatrogenic aortocoronary dissection (IACD) is a rare but potentially fatal complication of percutaneous coronary intervention or coronary angiography (CAG). In particular, if the condition of the patient is complicated by cardiogenic shock and right ventricular (RV) dysfunction, the mortality rate is high. Herein, we report the case of an 85-year-old woman with IACD who underwent elective CAG of the right coronary artery complicated with cardiogenic shock due to RV infarction. After prompt surgical repair and postoperative extracorporeal membrane oxygenation, the postoperative course was uneventful and the patient was discharged to a rehabilitation facility.

Inhaled nitric oxide suppresses neuroinflammation in experimental ischemic stroke

Ischemic stroke is a major global health issue and characterized by acute vascular dysfunction and subsequent neuroinflammation. However, the relationship between these processes remains elusive. In the current study, we investigated whether alleviating vascular dysfunction by restoring vascular nitric oxide (NO) reduces post-stroke inflammation. Mice were subjected to experimental stroke and received inhaled NO (iNO; 50 ppm) after reperfusion. iNO normalized vascular cyclic guanosine monophosphate (cGMP) levels, reduced the elevated expression of intercellular adhesion molecule-1 (ICAM-1), and returned leukocyte adhesion to baseline levels. Reduction of vascular pathology significantly reduced the inflammatory cytokines interleukin-1β (Il-1β), interleukin-6 (Il-6), and tumor necrosis factor-α (TNF-α), within the brain parenchyma. These findings suggest that vascular dysfunction is responsible for leukocyte adhesion and that these processes drive parenchymal inflammation. Reversing vascular dysfunction may therefore emerge as a novel approach to diminish neuroinflammation after ischemic stroke and possibly other ischemic disorders.

Haemodynamic effects of inhaled nitric oxide in acute myocardial infarction complicated by right heart failure under ECPELLA support: case report

Background

Recently, mechanical support obtained with the combination of venoarterial extracorporeal membrane oxygenation (VA-ECMO) and an Impella device, together referred to as ECPELLA, has been shown to be effective for acute myocardial infarction with cardiogenic shock. However, methods for withdrawing VA-ECMO in acute myocardial infarction cases complicated by right ventricular dysfunction are yet to be established. Here, we report the effective use of inhaled nitric oxide during the weaning of VA-ECMO from the ECPELLA management of a patient with acute myocardial infarction with cardiogenic shock.

Case summary

An 81-year-old man with an acute extensive anterior wall myocardial infarction with cardiogenic shock was supported with ECPELLA to improve his haemodynamics. During ECPELLA, the Impella device could not maintain sufficient flow. Echocardiography revealed a small left ventricle and an enlarged right ventricle, indicating acute right heart failure. Inhaled nitric oxide was initiated to reduce right ventricle afterload, which decreased pulmonary artery pressure from 34/20 to 27/13 mmHg, improved right and left ventricle sizes, and stabilized the Impella support. Afterward, VA-ECMO could be withdrawn because the Impella alone was sufficient for haemodynamic support.

Discussion

Inhaled nitric oxide improved right ventricle performance in a patient with severe myocardial infarction with right heart failure supported by ECPELLA. Thus, we suggest that inhaled nitric oxide facilitates the weaning of VA-ECMO from patients with refractory right ventricular dysfunction who are supported by ECPELLA.

Optimal Conservative Management Resolves Refractory Hypoxemia in Patient with Right Myocardial Infarction Complicated by PFO-Induced Shunting

Inferior myocardial infarction is often accompanied by infarction of the right ventricle (RV). Uncommon RV infarction cases with patent foramen ovale (PFO) shunt, leading to severe persistent hypoxemia even without any pulmonary embolism involvement and often requiring invasive intervention, have been documented previously. We report a patient with RV infarction and right-to-left shunt via PFO who improved with only early revascularization and optimal standard treatment. This condition may not necessitate any invasive intervention if it is treated and monitored per standard procedures. Clinicians should consider the possibility of a right-to-left shunt in patients with RV infarction and persistent hypoxemia to implement appropriate therapeutic interventions.

An Update on the Diagnosis and Management of Acute Right Heart Failure

Right ventricular (RV) dysfunction and resultant acute right heart failure (ARHF) is a rapidly growing field of interest, driven by increasing appreciation of its contribution to heart failure morbidity and mortality. Understanding of ARHF pathophysiology has advanced dramatically over recent years and can be broadly described as RV dysfunction related to acute changes in RV afterload, contractility, preload, or left ventricular dysfunction. There are several diagnostic clinical signs and symptoms as well as imaging and hemodynamic assessments that can provide insight into the degree of RV dysfunction. Medical management is tailored to the different causative pathologies, and in cases of severe or end-stage dysfunction, mechanical circulatory support can be utilized. In this review, we describe the pathophysiology of ARHF, how its diagnosis is established by clinical signs and symptoms and imaging findings, and provide an overview of treatment options, both medical and mechanical.

Adverse events from nitrate administration during right ventricular myocardial infarction: a systematic review and meta-analysis

BACKGROUND

The current guidelines of the American Heart Association (AHA) and European Society of Cardiology (ESC) recommend that when right ventricular myocardial infarction (RVMI) is present patients are not administered nitrates, due to the risk that decreasing preload in the setting of already compromised right ventricular ejection fraction may reduce cardiac output and precipitate hypotension. The cohort study (n=40) underlying this recommendation was recently challenged by new studies suitable for meta-analysis (cumulatively, n=1050), suggesting that this topic merits systematic review.

METHODS

The protocol was registered on PROSPERO and published in Evidence Synthesis. Six databases were systematically searched in May 2022: PubMed, Embase, MEDLINE Complete, Cochrane CENTRAL Register, CINAHL and Google Scholar. Two investigators independently assessed for quality and bias and extracted data using Joanna Briggs Institute tools and methods. Risk ratios and 95% CIs were calculated, and meta-analysis performed using the random effects inverse variance method.

RESULTS

Five studies (n=1113) were suitable. Outcomes included haemodynamics, GCS, syncope, arrest and death. Arrest and death did not occur in the RVMI group. Meta-analysis was possible for sublingual nitroglycerin 400 μg (2 studies, n=1050) and found no statistically significant difference in relative risk to combined inferior and RVMI at 1.31 (95% CI 0.81 to 2.12, p=0.27), with an absolute effect of 3 additional adverse events per 100 treatments. Results remained robust under sensitivity analysis.

CONCLUSIONS

This review suggests that the AHA and ESC contraindications are not supported by evidence. Key limitations include all studies having concomitant inferior and RVMI, not evaluating beneficial effects and very low certainty of evidence. As adverse events are transient and easily managed, nitrates are a reasonable treatment modality to consider during RVMI on current evidence.

PROSPERO REGISTRATION NUMBER

CRD42020172839.

Role of Nitric Oxide and Protein S-Nitrosylation in Ischemia-Reperfusion Injury

Ischemia-reperfusion injury (IRI) is a process in which damage is induced in hypoxic tissue when oxygen supply is resumed after ischemia. During IRI, restoration of reduced nitric oxide (NO) levels may alleviate reperfusion injury in ischemic organs. The protective mechanism of NO is due to anti-inflammatory effects, antioxidant effects, and the regulation of cell signaling pathways. On the other hand, it is generally known that S-nitrosylation (SNO) mediates the detrimental or protective effect of NO depending on the action of the nitrosylated target protein, and this is also applied in the IRI process. In this review, the effect of each change of NO and SNO during the IRI process was investigated.

Vasoactive pharmacologic therapy in cardiogenic shock: a critical review

Background

Cardiogenic shock (CS) is an acute complex condition leading to morbidity and mortality. Vasoactive medications, such as vasopressors and inotropes are considered the cornerstone of pharmacological treatment of CS to improve end-organ perfusion by increasing cardiac output (CO) and blood pressure (BP), thus preventing multiorgan failure.

Objective

A critical review was conducted to analyze the currently available randomized studies of vasoactive agents in CS to determine the indications of each agent and to critically appraise the methodological quality of the studies.

Methods

PubMed database search was conducted to identify randomized controlled trials (RCTs) on vasoactive therapy in CS. After study selection, the internal validity of the selected studies was critically appraised using the three-item Jadad scale.

Results

Nine studies randomized 2388 patients with a mean age ranged between 62 and 69 years, were identified. Seven of studies investigated CS in the setting of acute myocardial infarction (AMI). The studies evaluated the comparisons of norepinephrine (NE) vs. dopamine, epinephrine vs. NE, levosimendan vs. dobutamine, enoximone or placebo, and nitric oxide synthase inhibitors (NOSi) vs. placebo. The mean Jadad score of the nine studies was 3.33, with only three studies of a score of 5.

Conclusions

The evidence from the studies of vasoactive agents in CS carries uncertainties. The methodological quality between the studies is variable due to the inherent difficulties to conduct a study in CS. Vasopressors and inotropes continue to have a fundamental role given the lack of pharmacological alternatives.

Perioperative echocardiography-guided hemodynamic therapy in high-risk patients: a practical expert approach of hemodynamically focused echocardiography

The number of high-risk patients undergoing surgery is growing. To maintain adequate hemodynamic functioning as well as oxygen delivery to the vital organs (DO2) amongst this patient population, a rapid assessment of cardiac functioning is essential for the anesthesiologist. Pinpointing any underlying cardiovascular pathophysiology can be decisive to guide interventions in the intraoperative setting. Various techniques are available to monitor the hemodynamic status of the patient, however due to intrinsic limitations, many of these methods may not be able to directly identify the underlying cause of cardiovascular impairment. Hemodynamic focused echocardiography, as a rapid diagnostic method, offers an excellent opportunity to examine signs of filling impairment, cardiac preload, myocardial contractility and the function of the heart valves. We thus propose a 6-step-echocardiographic approach to assess high-risk patients in order to improve and maintain perioperative DO2. The summary of all echocardiographic based findings allows a differentiated assessment of the patient's cardiovascular function and can thus help guide a (patho)physiological-orientated and individualized hemodynamic therapy.

Clinical application of nitric oxide in ischemia and reperfusion injury: A literature review

Ischemia–reperfusion injury (IRI) is a series of multifactorial cellular events that lead to increased cellular dysfunction after the restoration of oxygen delivery to hypoxic tissue, which can result in acute heart failure and cerebral dysfunction. This injury is severe and would lead to significant morbidity and mortality and poses an important therapeutic challenge for physicians. Nitric oxide (NO) minimizes the deleterious effects of IRI on cells. NO donors, such as organic nitrates and sodium nitroprusside, are used systematically to treat heart failure, angina, and pulmonary hypertension. Inhaled NO gas was approved by the FDA in 1999 to treat hypoxic newborns, and its beneficial ameliorations reach outside the realm of lung disease. This review will summarize the clinical application of NO in IRI.

Pulmonary vasodilators: beyond the bounds of pulmonary arterial hypertension therapy in COVID-19

Pulmonary arterial hypertension (PAH) and novel coronavirus (SARS-CoV-2) disease COVID-19 are characterized by extensive endothelial dysfunction and inflammation leading to vascular remodeling and severe microthrombi and microvascular obliterative disease. It is hypothesized that those patients with underlying lung disease, like PAH, represent a high-risk cohort in this pandemic. However, reports of COVID-19 in this cohort of patient have been scaring and an observational survey showed that the disease was relatively well tolerated. We postulate that specific PAH vasodilator may offer some protection and/or advantage in the case of concomitant COVID-19. Here we review the literature describing mechanisms of action for each of the broad categories of PAH therapy, and offer potential hypothesis about why this therapy may impact outcomes in COVID-19.

Initial experience with Impella RP in a quaternary transplant center

Right ventricular failure is one of the most common complications encountered after left ventricular assist device implantation and heart transplantation. It has been reported to have an incidence up to 30%. It increases morbidity and short-term mortality. Impella RP is a small pump that can provide up to 4L/min of flow. We analyzed all the patients with right ventricular failure that were treated with Impella RP in our institution. The Impella RP was implanted percutaneously in the catheterization laboratory guided by fluoroscopy. Overall, 7 patients required the implantation of an Impella RP due to right ventricular failure: 2 after long-term LVAD, 3 presented with acute right ventricular failure immediately after LVAD implantation, and 2 needed it after heart transplantation. Regarding complications, we report 2 patients with hemolysis. Hemodynamic parameters as well as end-organ perfusion and inotropic requirements improved after the insertion of the Impella. Overall, 30-day survival is 58%. Median time of support was 9 (5-19) days. RV failure is one of the most challenging complications after LVAD implantation and heart transplantation. The major challenge is the timing of implantation. The minimally invasive nature of the Impella RP facilitates de-escalation of treatment and paves the road to recovery. Impella RP proved useful in facilitating ECMO wean. Used in a prompt manner alongside the ease of implantation and the minimal rate of complications, Impella RP seems to be an appropriate device to tackle RV failure providing enough flow to allow for recovery or escalation decision-making.

Nitric oxide for inhalation in ST-elevation myocardial infarction (NOMI): a multicentre, double-blind, randomized controlled trial

Aims

Inhalation of nitric oxide (iNO) during myocardial ischaemia and after reperfusion confers cardioprotection in preclinical studies via enhanced cyclic guanosine monophosphate (cGMP) signalling. We tested whether iNO reduces reperfusion injury in patients with ST-elevation myocardial infarction (STEMI; NCT01398384).

Methods and results

We randomized in a double-blind, placebo-controlled study 250 STEMI patients to inhale oxygen with (iNO) or without (CON) 80 parts-per-million NO for 4 h following percutaneous revascularization. Primary efficacy endpoint was infarct size as a fraction of left ventricular (LV) size (IS/LVmass), assessed by delayed enhancement contrast magnetic resonance imaging (MRI). Pre-specified subgroup analysis included thrombolysis-in-myocardial-infarction flow in the infarct-related artery, troponin T levels on admission, duration of symptoms, location of culprit lesion, and intra-arterial nitroglycerine (NTG) use. Secondary efficacy endpoints included IS relative to risk area (IS/AAR), myocardial salvage index, LV functional recovery, and clinical events at 4 and 12 months. In the overall population, IS/LVmass at 48-72 h was 18.0 ± 13.4% in iNO (n = 109) and 19.4 ± 15.4% in CON [n = 116, effect size -1.524%, 95% confidence interval (95% CI) -5.28, 2.24; P = 0.427]. Subgroup analysis indicated consistency across clinical confounders of IS but significant treatment interaction with NTG (P = 0.0093) resulting in smaller IS/LVmass after iNO in NTG-naïve patients (n = 140, P < 0.05). The secondary endpoint IS/AAR was 53 ± 26% with iNO vs. 60 ± 26% in CON (effect size -6.8%, 95% CI -14.8, 1.3, P = 0.09) corresponding to a myocardial salvage index of 47 ± 26% vs. 40 ± 26%, respectively, P = 0.09. Cine-MRI showed similar LV volumes at 48-72 h, with a tendency towards smaller increases in end-systolic and end-diastolic volumes at 4 months in iNO (P = 0.048 and P = 0.06, respectively, n = 197). Inhalation of nitric oxide was safe and significantly increased cGMP plasma levels during 4 h reperfusion. The Kaplan-Meier analysis for the composite of death, recurrent ischaemia, stroke, or rehospitalizations showed a tendency toward lower event rates with iNO at 4 months and 1 year (log-rank test P = 0.10 and P = 0.06, respectively).

Conclusions

Inhalation of NO at 80 ppm for 4 h in STEMI was safe but did not reduce infarct size relative to absolute LVmass at 48-72h. The observed functional recovery and clinical event rates at follow-up and possible interaction with nitroglycerine warrant further studies of iNO in STEMI.

Noninvasive Administration of Inhaled Nitric Oxide and its Hemodynamic Effects in Patients With Acute Right Ventricular Dysfunction

OBJECTIVE

The authors aimed to assess the hemodynamic effects and demonstrate the feasibility of inhaled nitric oxide (iNO) in hemodynamically unstable patients with acute right ventricular (RV) dysfunction and to explore the safety profile of this approach.

DESIGN

Retrospective cohort study.

SETTING

Intensive care unit (ICU) of 2 tertiary care centers between January 2013 and 2017.

PARTICIPANTS

All patients with RV dysfunction in whom iNO was initiated without invasive mechanical ventilation.

INTERVENTION

Noninvasive administration of iNO.

MEASUREMENTS AND MAIN RESULTS

Eighteen patients received the intervention during the study period; 8 of these patients had a pulmonary artery catheter and 2 had a pulse contour analysis device. Median (interquartile range) iNO concentration was 20 (20-20) ppm, and therapy duration was 24 (12-46) hours. Most patients received iNO through nasal prongs (66.7%) or a high-flow nasal cannula (27.8%). Within 1 hour, iNO reduced pulmonary vascular resistance from 219.1 to 165.4 dyn•s/cm⁵ (n = 7; p < 0.001), mean pulmonary artery pressure from 28.4 to 25.3 mmHg (n = 8; p = 0.01), and central venous pressure from 17.5 to 13.1 mmHg (n = 16; p = 0.001). Indexed cardiac output increased from 2.0 to 2.6 L/min/m² (n = 9; p = 0.004). ICU mortality was 27.78%, and median ICU length of stay was 7 (5-9) days. Two significant bleeding episodes requiring intervention and 1 acute kidney injury occurred during iNO therapy. No headache was reported.

CONCLUSION

Noninvasively administered iNO was associated with favorable hemodynamic effects in ICU patients with acute RV dysfunction. These results suggest the safety and feasibility of this therapy for which further prospective study is warranted.

Evaluation and Management of Right-Sided Heart Failure: A Scientific Statement From the American Heart Association

Background and Purpose:

The diverse causes of right-sided heart failure (RHF) include, among others, primary cardiomyopathies with right ventricular (RV) involvement, RV ischemia and infarction, volume loading caused by cardiac lesions associated with congenital heart disease and valvular pathologies, and pressure loading resulting from pulmonic stenosis or pulmonary hypertension from a variety of causes, including left-sided heart disease. Progressive RV dysfunction in these disease states is associated with increased morbidity and mortality. The purpose of this scientific statement is to provide guidance on the assessment and management of RHF.

Methods:

The writing group used systematic literature reviews, published translational and clinical studies, clinical practice guidelines, and expert opinion/statements to summarize existing evidence and to identify areas of inadequacy requiring future research. The panel reviewed the most relevant adult medical literature excluding routine laboratory tests using MEDLINE, EMBASE, and Web of Science through September 2017. The document is organized and classified according to the American Heart Association to provide specific suggestions, considerations, or reference to contemporary clinical practice recommendations.

Results:

Chronic RHF is associated with decreased exercise tolerance, poor functional capacity, decreased cardiac output and progressive end-organ damage (caused by a combination of end-organ venous congestion and underperfusion), and cachexia resulting from poor absorption of nutrients, as well as a systemic proinflammatory state. It is the principal cause of death in patients with pulmonary arterial hypertension. Similarly, acute RHF is associated with hemodynamic instability and is the primary cause of death in patients presenting with massive pulmonary embolism, RV myocardial infarction, and postcardiotomy shock associated with cardiac surgery. Functional assessment of the right side of the heart can be hindered by its complex geometry. Multiple hemodynamic and biochemical markers are associated with worsening RHF and can serve to guide clinical assessment and therapeutic decision making. Pharmacological and mechanical interventions targeting isolated acute and chronic RHF have not been well investigated. Specific therapies promoting stabilization and recovery of RV function are lacking.

Conclusions:

RHF is a complex syndrome including diverse causes, pathways, and pathological processes. In this scientific statement, we review the causes and epidemiology of RV dysfunction and the pathophysiology of acute and chronic RHF and provide guidance for the management of the associated conditions leading to and caused by RHF.

Perioperative transesophageal echocardiography for non-cardiac surgery

PURPOSE

The use of transesophageal echocardiography (TEE) has evolved to include patients undergoing high-risk non-cardiac procedures and patients with significant cardiac disease undergoing non-cardiac surgery. Implementation of basic TEE education in training programs has increased across a broad spectrum of procedures in the perioperative arena. This paper describes the use of perioperative TEE in non-cardiac surgery and provides an overview of the basic TEE examination.

PRINCIPAL FINDINGS

Perioperative TEE is used to monitor hemodynamic parameters in non-cardiac procedures where there is a high risk of hemodynamic instability. Its use extends to include moderate-risk procedures for patients with significant cardiac diseases such as low ejection fraction, hypertrophic cardiomyopathy, severe valve lesions, or congenital heart disease. Vascular procedures involving the aorta, blunt trauma, and liver transplantation are all examples of procedures that may benefit from TEE. Transesophageal echocardiography examination allows assessment of volume status, ventricular function, diagnosis of gross valvular pathology and pericardial tamponade, as well as close monitoring of cardiac output, response to therapy, and the impact of ongoing surgical manipulation. In patients with unexplained and unexpected hemodynamic instability, "rescue TEE" can be used to help identify the underlying cause.

CONCLUSIONS

Perioperative TEE is emerging as a preferred tool to manage hemodynamics in high-risk procedures and in high-risk patients undergoing non-cardiac surgery. A rescue TEE examination protocol is a helpful approach for early identification of the etiology of hemodynamic instability.

Hospital and intensive care unit management of decompensated pulmonary hypertension and right ventricular failure

Pulmonary hypertension and concomitant right ventricular failure present a diagnostic and therapeutic challenge in the intensive care unit and have been associated with a high mortality. Significant co-morbidities and hemodynamic instability are often present, and routine critical care unit resuscitation may worsen hemodynamics and limit the chances of survival in patients with an already underlying poor prognosis. Right ventricular failure results from structural or functional processes that limit the right ventricle’s ability to maintain adequate cardiac output. It is commonly seen as the result of left heart failure, acute pulmonary embolism, progression or decompensation of pulmonary hypertension, sepsis, acute lung injury, or in the perioperative setting. Prompt recognition of the underlying cause and institution of treatment with a thorough understanding of the elements necessary to optimize preload, cardiac contractility, enhance systemic arterial perfusion, and reduce right ventricular afterload are of paramount importance. Moreover, the emergence of previously uncommon entities in patients with pulmonary hypertension (pregnancy, sepsis, liver disease, etc.) and the availability of modern devices to provide support pose additional challenges that must be addressed with an in-depth knowledge of this disease.

Management of the Critically Ill Adult With Congenital Heart Disease

Survival of adults with congenital heart disease (CHD) has improved significantly over the last 2 decades, leading to an increase in hospital and intensive care unit (ICU) admissions of these patients. Whereas most of the ICU admissions in the past were related to perioperative management, the incidence of medical emergencies from long-term sequelae of palliative or corrective surgical treatment of these patients is rising. Intensivists now are confronted with patients who not only have complex anatomy after congenital cardiac surgery, but also complex pathophysiology due to decades of living with abnormal cardiac anatomy and diseases of advanced age. Comorbidities affect all organ systems, including cognitive function, pulmonary and cardiovascular systems, liver, and kidneys. Critical care management requires an in-depth understanding of underlying anatomy and pathophysiology in order to apply contemporary concepts of adult ICU care to this population and optimize patient outcomes. In this review, the main CHD lesions and their common surgical management approaches are described, and the sequelae of CHD physiology are discussed. In addition, the effects of chronic comorbidities on the management of critically ill adults are explored, and the adjustments of current ICU management modalities and pharmacology to optimize care are discussed.

Contemporary Management of Cardiogenic Shock: A Scientific Statement From the American Heart Association

Cardiogenic shock is a high-acuity, potentially complex, and hemodynamically diverse state of end-organ hypoperfusion that is frequently associated with multisystem organ failure. Despite improving survival in recent years, patient morbidity and mortality remain high, and there are few evidence-based therapeutic interventions known to clearly improve patient outcomes. This scientific statement on cardiogenic shock summarizes the epidemiology, pathophysiology, causes, and outcomes of cardiogenic shock; reviews contemporary best medical, surgical, mechanical circulatory support, and palliative care practices; advocates for the development of regionalized systems of care; and outlines future research priorities.

Acute and Chronic Right Ventricular Failure

Right ventricular failure is the subject of renewed attention as the importance of RV function in a variety of disease states has been recognized. The RV is highly compliant, and is able to accommodate a wide range of preload conditions. Yet, it is afterload-sensitive, and normal physiology is dependent on its association with the low resistance of the pulmonary vasculature. Changes in the pulmonary vascular resistance, either acutely or over time, provoke a series of adaptations that are designed to maintain a normal cardiac output, but ultimately lead to decompensation and RV failure. Through ventricular interdependence, RV failure may impair left ventricular diastolic and systolic function, further reducing cardiac performance. Both echocardiography and magnetic resonance imaging can provide detailed information about RV structure, with MRI providing better assessment of ventricular volumes and RV function. Right heart catheterization is often necessary for definitive diagnosis of the etiology of RV failure and for determining the best therapeutic options. The treatment of RV failure is highly dependent on the underlying etiology, which should be corrected if possible. Targeted medical therapy is particularly useful in cases of pulmonary arterial hypertension, and is under investigation for broader use in other causes of pulmonary hypertension.

Isolated right ventricular infarction: a diagnostic challenge

A 73-year-old woman was admitted to the emergency room due to sudden-onset dyspnoea, altered mental status and haemodynamic instability. ECG showed a junctional rhythm, T-wave inversion in I, aVL and V2-V6 (present in a previous ECG), and no ST/T changes in the right precordial leads. Transthoracic echocardiography, however, revealed a severe depression of global systolic function of right ventricle with akinesia of free wall and a normal left ventricular function. Coronary angiography showed an occlusion of the proximal segment of the right coronary artery, which was treated with balloon angioplasty, and a chronic lesion of the anterior descending artery. The patient had a good recovery and was discharged on the 14th day. Myocardial perfusion scintigraphy (stress and rest) was performed a month later, showing a fixed perfusion defect in the apex and anterior wall (medium-apical), with no signs of ischaemia.

High-flow oxygen therapy and other inhaled therapies in intensive care units

In this Series paper, we review the current evidence for the use of high-flow oxygen therapy, inhaled gases, and aerosols in the care of critically ill patients. The available evidence supports the use of high-flow nasal cannulae for selected patients with acute hypoxaemic respiratory failure. Heliox might prevent intubation or improve gas flow in mechanically ventilated patients with severe asthma. Additionally, it might improve the delivery of aerosolised bronchodilators in obstructive lung disease in general. Inhaled nitric oxide might improve outcomes in a subset of patients with postoperative pulmonary hypertension who had cardiac surgery; however, it has not been shown to provide long-term benefit in patients with acute respiratory distress syndrome (ARDS). Inhaled prostacyclins, similar to inhaled nitric oxide, are not recommended for routine use in patients with ARDS, but can be used to improve oxygenation in patients who are not adequately stabilised with traditional therapies. Aerosolised bronchodilators are useful in mechanically ventilated patients with asthma and chronic obstructive pulmonary disease, but are not recommended for those with ARDS. Use of aerosolised antibiotics for ventilator-associated pneumonia and ventilator-associated tracheobronchitis shows promise, but the delivered dose can be highly variable if proper attention is not paid to the delivery method.

Management of pulmonary hypertension and right heart failure in the intensive care unit

Management of acute right ventricular failure, both with and without coexisting pulmonary hypertension, is a common challenge encountered in the intensive care setting. Both right ventricular dysfunction and pulmonary hypertension portend a poor prognosis, regardless of the underlying cause and are associated with significant morbidity and mortality. The right ventricle is embryologically distinct from the left ventricle and has unique morphologic and functional properties. Management of right ventricular failure and pulmonary hypertension in the intensive care setting requires tailored hemodynamic management, pharmacotherapy, and often mechanical circulatory support. Unfortunately, our understanding of the management of right ventricular failure lags behind that of the left ventricle. In this review, we will explore the underlying pathophysiology of the failing right ventricle and pulmonary vasculature in patients with and without pulmonary hypertension and discuss management strategies based on evidence-based studies as well as our current understanding of the underlying physiology.

[Management of patients with pulmonary hypertension]

Due to the increased survival of patients with pulmonary hypertension, even non-cardiac anesthesiologists will see these patients more frequently for anesthesia. The hemodynamic goal in the perioperative period is to avoid an increase in pulmonary vascular resistance (PVR) and to reduce a possibly pre-existing elevated PVR. Acute increases of chronically elevated PVR may result from hypoxia, hypercapnia, acidosis, hypothermia, elevated sympathetic output and also release of endogenous or application of exogenous pulmonary vasoconstrictors. Early recognition and treatment of these changes might be life saving in these patients. Drug interventions to perioperatively reduce PVR include administration of pulmonary vasodilators, such as oxygen, prostacyclines (epoprostenol, iloprost), phosphodiesterase III (milrinone) and V (sildenafil) inhibitors, as well as nitrates and nitric oxide. Along with the concept of selective pulmonary vasodilation inhalative administration of pulmonary vasodilators has benefits compared to intravenous administration. New therapeutic strategies, such as inhalational iloprost, inhalational milrinone and intravenous sildenafil can be introduced without significant technical support even in smaller departments.

Inhaled Nitric Oxide: A Review of the Action, Current Literature, and An Analysis of its Use in the NHS Today

Nitric oxide is a potent vasodilator which when inhaled causes dilatation in the pulmonary vasculature. It is this action that has been studied in intensive care medicine, especially in relation to hypoxic vasoconstriction associated with acute respiratory distress syndrome (ARDS). The use of inhaled nitric oxide has been shown to improve ventilation:perfusion matching, and thus to improve oxygenation. This article reviews the chemistry and clinical properties of nitric oxide as well as its potential uses, clinical effectiveness and side effects. The authors also surveyed UK intensive care units to review the current prevalence of the use of inhaled nitric oxide. It was found that while the majority do not currently use inhaled nitric oxide in ARDS patients, it had still been used in 27% (n=61) of the departments surveyed.

Right side of heart failure

The function of the right ventricle (RV) in heart failure (HF) has been mostly ignored until recently. A 2006 report of the National Heart, Lung, and Blood Institute identified a gap between RV research efforts and its clinical importance compared with that of the left ventricle. This recent shift in paradigm is fueled by the prognostic value ascribed to RV failure in HF and morbidity/mortality after myocardial infarction and surgery. In this review, we examine the significance of RV failure in the HF setting, its clinical presentation and pathophysiology, and ways to evaluate RV function using echocardiographic measurements. Furthermore, we discuss the medical management of RV failure including traditional therapies like beta-blockers and newer options like nitric oxide, phosphodiesterase inhibitors, and calcium sensitizers. Mechanical support is also examined. Finally, this review places an emphasis on RV failure in the setting of left ventricular assist devices and heart transplantation.

Right ventricular failure in congenital heart disease

Despite developments in surgical techniques and other interventions, right ventricular (RV) failure remains an important clinical problem in several congenital heart diseases (CHD). RV function is one of the most important predictors of mortality and morbidity in patients with CHD. RV failure is a progressive disorder that begins with myocardial injury or stress, neurohormonal activation, cytokine activation, altered gene expression, and ventricular remodeling. Pressure-overload RV failure caused by RV outflow tract obstruction after total correction of tetralogy of Fallot, pulmonary stenosis, atrial switch operation for transposition of the great arteries, congenitally corrected transposition of the great arteries, and systemic RV failure after the Fontan operation. Volume-overload RV failure may be caused by atrial septal defect, pulmonary regurgitation, or tricuspid regurgitation. Although the measurement of RV function is difficult because of many reasons, the right ventricle can be evaluated using both imaging and functional modalities. In clinical practice, echocardiography is the primary mode for the evaluation of RV structure and function. Cardiac magnetic resonance imaging is increasingly used for evaluating RV structure and function. A comprehensive evaluation of RV function may lead to early and optimal management of RV failure in patients with CHD.

Clinical perspectives with long-term pulsed inhaled nitric oxide for the treatment of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a chronic, progressive disease of the pulmonary vasculature with a high morbidity and mortality. Its pathobiology involves at least three interacting pathways – prostacyclin (PGI₂), endothelin, and nitric oxide (NO). Current treatments target these three pathways utilizing PGI₂ and its analogs, endothelin receptor antagonists, and phosphodiesterase type-5 (PDE-5) inhibitors. Inhaled nitric oxide (iNO) is approved for the treatment of hypoxic respiratory failure associated with pulmonary hypertension in term/near-term neonates. As a selective pulmonary vasodilator, iNO can acutely decrease pulmonary artery pressure and pulmonary vascular resistance without affecting cardiac index or systemic vascular resistance. In addition to delivery via the endotracheal tube, iNO can also be administered as continuous inhalation via a facemask or a pulsed nasal delivery. Consistent with a deficiency in endogenously produced NO, long-term pulsed iNO dosing appears to favorably affect hemodynamics in PAH patients, observations that appear to correlate with benefit in uncontrolled settings. Clinical studies and case reports involving patients receiving long-term continuous pulsed iNO have shown minimal risk in terms of adverse events, changes in methemoglobin levels, and detectable exhaled or ambient NO or NO₂. Advances in gas delivery technology and strategies to optimize iNO dosing may enable broad-scale application to long-term treatment of chronic diseases such as PAH.

Inhalation of NO during myocardial ischemia reduces infarct size and improves cardiac function

PURPOSE

Bioactive NO carriers in circulating blood formed during NO inhalation selectively distribute blood flow to areas in need, and may thus improve collateral perfusion to the area-at-risk in acute myocardial infarction (AMI). Here, we tested the hypothesis that NO inhalation during the ischemic phase of AMI may improve left ventricular function and reduce infarct size in rats.

METHODS

Following left anterior descending coronary artery (LAD) occlusion, rats received 50 ppm NO for 2 h of ischemia, during subsequent 3 h of reperfusion, or for 5 h of ischemia and reperfusion. Effects of inhaled NO were compared to those of intravenous nitrite as a putative carrier formed during NO inhalation. Downstream signaling via soluble guanylate cyclase was tested by inhibition with 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ).

RESULTS

NO inhalation during myocardial ischemia increased left ventricular systolic pressure, contractility, relaxation, and cardiac output, and reduced myocardial infarction size and area-at-risk as compared to untreated controls. NO inhalation during the reperfusion phase caused a comparable protective effect. Combined inhalation during ischemia and reperfusion did not further improve left ventricular hemodynamics, but had an additive protective effect on the myocardial area-at-risk. NO inhalation increased circulating nitrite levels, and mimicking of this effect by intravenous nitrite infusion achieved similar protection as NO inhalation during myocardial ischemia, while ODQ blocked the protective NO effect.

CONCLUSIONS

Inhalation of NO during myocardial ischemia improves left ventricular function and reduces infarct size by mechanisms that increase levels of circulating nitrite and involve soluble guanylate cyclase. NO inhalation may represent a promising early intervention in AMI.

Inhalation of nitric oxide prevents ischemic brain damage in experimental stroke by selective dilatation of collateral arterioles

RATIONALE

Stroke is the third most common cause of death in industrialized countries. The main therapeutic target is the ischemic penumbra, potentially salvageable brain tissue that dies within the first few hours after blood flow cessation. Hence, strategies to keep the penumbra alive until reperfusion occurs are needed.

OBJECTIVE

To study the effect of inhaled nitric oxide on cerebral vessels and cerebral perfusion under physiological conditions and in different models of cerebral ischemia.

METHODS AND RESULTS

This experimental study demonstrates that inhaled nitric oxide (applied in 30% oxygen/70% air mixture) leads to the formation of nitric oxide carriers in blood that distribute throughout the body. This was ascertained by in vivo microscopy in adult mice. Although under normal conditions inhaled nitric oxide does not affect cerebral blood flow, after experimental cerebral ischemia induced by transient middle cerebral artery occlusion it selectively dilates arterioles in the ischemic penumbra, thereby increasing collateral blood flow and significantly reducing ischemic brain damage. This translates into significantly improved neurological outcome. These findings were validated in independent laboratories using two different mouse models of cerebral ischemia and in a clinically relevant large animal model of stroke.

CONCLUSIONS

Inhaled nitric oxide thus may provide a completely novel strategy to improve penumbral blood flow and neuronal survival in stroke or other ischemic conditions.

Effects of a percutaneous mechanical circulatory support device for medically refractory right ventricular failure

BACKGROUND

Medically refractory right ventricular failure (MR-RVF) is associated with high in-hospital mortality and is managed with surgical assist devices, atrial septostomy, or extracorporeal membrane oxygenation. This study explored the hemodynamic effect associated with a percutaneous RV support device (pRVSD) for MR-RVF.

METHODS

Between 2008 and 2010, 9 patients with MR-RVF, defined as cardiogenic shock despite maximal medical therapy, were treated with a pRVSD. Medical records were reviewed for demographics, hemodynamic and laboratory data, and details of pRVSD implantation.

RESULTS

MR-RVF was due to severe sepsis in 1 patient (11.1%), post-cardiotomy syndrome in 2 (22.2%), and acute inferior wall myocardial infarction (IWMI) in 6 (66.7%). Five patients underwent right internal jugular-to-femoral cannulation, and 4 required bifemoral cannulation. No intra-procedural deaths or major vascular complications requiring surgical or peripheral intervention occurred. Time from admission to pRVSD implantation was 2.9 ± 3.3 days, with an average of 6516 ± 698 rotations/min, providing flow at 3.3 ± 0.4 liters/min. Mean duration of pRVSD activation was 3.1 ± 1.8 days. Compared with pre-procedural values, mean arterial pressure (57 ± 7 vs 75 ± 19 mm Hg, p < 0.05), right atrial pressure (22 ± 3 vs 15 ± 6 mm Hg, p < 0.05), cardiac index (1.5 ± 0.4 vs 2.3 ± 0.5 liters/min/m(2), p < 0.05), mixed venous oxygen saturation (40 ± 14 vs 58 ± 4 percent, p < 0.05), and RV stroke work (3.4 ± 3.9 vs 9.7 ± 6.8 g · m/beat, p < 0.05) improved significantly within 24 hours of pRVSD implantation. In-hospital mortality was 44% (n = 4). Time from admission to pRVSD placement was lower in patients who survived to hospital discharge (0.9 ± 0.8 days) vs non-survivors (4.8 ± 3.5 days; p = 0.04). All survivors presented with IWMI.

CONCLUSION

Use of a pRVSD for MR-RVF is feasible and associated with improved hemodynamics. Algorithms promoting earlier pRVSD use in MR-RVF warrant further investigation.

Pulmonary vascular and right ventricular dysfunction in adult critical care: current and emerging options for management: a systematic literature review

INTRODUCTION

Pulmonary vascular dysfunction, pulmonary hypertension (PH), and resulting right ventricular (RV) failure occur in many critical illnesses and may be associated with a worse prognosis. PH and RV failure may be difficult to manage: principles include maintenance of appropriate RV preload, augmentation of RV function, and reduction of RV afterload by lowering pulmonary vascular resistance (PVR). We therefore provide a detailed update on the management of PH and RV failure in adult critical care.

METHODS

A systematic review was performed, based on a search of the literature from 1980 to 2010, by using prespecified search terms. Relevant studies were subjected to analysis based on the GRADE method.

RESULTS

Clinical studies of intensive care management of pulmonary vascular dysfunction were identified, describing volume therapy, vasopressors, sympathetic inotropes, inodilators, levosimendan, pulmonary vasodilators, and mechanical devices. The following GRADE recommendations (evidence level) are made in patients with pulmonary vascular dysfunction: 1) A weak recommendation (very-low-quality evidence) is made that close monitoring of the RV is advised as volume loading may worsen RV performance; 2) A weak recommendation (low-quality evidence) is made that low-dose norepinephrine is an effective pressor in these patients; and that 3) low-dose vasopressin may be useful to manage patients with resistant vasodilatory shock. 4) A weak recommendation (low-moderate quality evidence) is made that low-dose dobutamine improves RV function in pulmonary vascular dysfunction. 5) A strong recommendation (moderate-quality evidence) is made that phosphodiesterase type III inhibitors reduce PVR and improve RV function, although hypotension is frequent. 6) A weak recommendation (low-quality evidence) is made that levosimendan may be useful for short-term improvements in RV performance. 7) A strong recommendation (moderate-quality evidence) is made that pulmonary vasodilators reduce PVR and improve RV function, notably in pulmonary vascular dysfunction after cardiac surgery, and that the side-effect profile is reduced by using inhaled rather than systemic agents. 8) A weak recommendation (very-low-quality evidence) is made that mechanical therapies may be useful rescue therapies in some settings of pulmonary vascular dysfunction awaiting definitive therapy.

CONCLUSIONS

This systematic review highlights that although some recommendations can be made to guide the critical care management of pulmonary vascular and right ventricular dysfunction, within the limitations of this review and the GRADE methodology, the quality of the evidence base is generally low, and further high-quality research is needed.

Do we have two hearts? New insights in right ventricular function supported by myocardial imaging echocardiography

RV performance is difficult to evaluate, given its geometry, interrelationship with the left ventricle, and sensitivity to alterations in pulmonary pressure. This article focuses on some of the challenges related to the assessment of RV function in the setting of the RV's unique anatomic, physiologic, conventional and newer echocardiographic aspects, and therapeutic implications. The majority of proposed methods of echocardiographic assessment of RV function are based on volumetric approximations of the RV. Such approaches have inherent limitations, first as volume-related measures such as EF are load dependent, second because of the complex geometry of the RV. The issue of RV geometry is usually overcome using geometry-independent parameters such as tricuspid annular excursion and the Tei index. The recent introduction of real-time three-dimensional echocardiography and myocardial imaging echocardiography (tissue Doppler imaging, 1D-strain and 2D-strain echocardiography) implied a great progress in echocardiography. Tissue Doppler imaging allows the quantitative assessment of RV systolic and diastolic function by means of measurement of myocardial velocities. Strain measurements have been shown to correlate well with sonomicrometry segment length measurements both in the inflow and outflow tract of the RV and under different loading conditions. Other findings have been reported in chronic and acute clinical settings. Standard and novel echocardiographic methods of assessment of RV size and performance can help clinicians in the treatment of acute and chronic RV failure and contribute to a better understanding of the peculiar chamber-related functional mechanisms in the context of ventricular interdependent independency.

Xenon and isoflurane improved biventricular function during right ventricular ischemia and reperfusion

BACKGROUND

Although anesthetics have some cardioprotective properties, these benefits are often counterbalanced by their negative inotropic effects. Xenon, on the other hand, does not influence myocardial contractility. Thus, xenon may be a superior treatment for the maintenance of global hemodynamics, especially during right ventricular ischemia, which is generally characterized by a high acute complication rate.

METHODS

The effects of 70 vol% xenon and 0.9 vol% isoflurane on biventricular function were assessed in a porcine model (n=36) using the conductance catheter technique, and the expression of the type B natriuretic peptide (BNP) gene was measured. The animals underwent 90 min of right ventricular ischemia followed by 120 min of reperfusion. A barbiturate-anesthetized group was included as a control.

RESULTS

Cardiac output was compromised in unprotected animals during ischemia by 33+/-18% and during reperfusion by 53+/-17%. This was mainly due to impaired contractility in the left ventricle (LV) and increased stiffness. Isoflurane attenuated the increase in stiffness and resulted in a higher preload. In contrast, xenon increased the right ventricular afterload, which was compensated by an increase in contractility. Its effects on diastolic function were less pronounced. Upregulation of BNP mRNA expression was impeded in the remote area of the LV by both isoflurane and xenon.

CONCLUSIONS

Xenon and isoflurane demonstrated equipotent effects in preventing the hemodynamic compromise that is induced by right ventricular ischemia and reperfusion, although they acted through somewhat differential inotropic and vasodilatory effects.

Right ventricular function in myocardial infarction complicated by cardiogenic shock: Improvement with levosimendan

OBJECTIVES

Levosimendan improves left ventricular hemodynamic function in patients with cardiogenic shock. However, its impact on right ventricular performance has not been determined. We compared the hemodynamic effects of levosimendan on left and right ventricular function in patients with intractable cardiogenic shock following myocardial infarction.

DESIGN

Observational hemodynamic study.

SETTING

Tertiary care center university hospital.

PATIENTS

Fifty-six patients with cardiogenic shock secondary to myocardial infarction were treated with percutaneous revascularization (including intra-aortic balloon pump when appropriate) and commenced on conventional inotropic therapy.

INTERVENTION

Twenty-five consecutive patients with cardiogenic shock due to myocardial infarction who had not improved sufficiently with conventional therapy (including dobutamine and norepinephrine) received levosimendan (as a bolus of 12 microg/kg per minute for 10 mins then 0.1 microg/kg per minute--0.2 mug/kg per minute) as "bail-out" therapy for 24 hrs while invasive hemodynamic parameters were recorded.

MEASUREMENTS AND MAIN RESULTS

Levosimendan therapy was associated with a significant increase in cardiac index from 2.1 +/- 0.1 to 3.0 +/- 0.2 L x min x m (p < .01). In addition, levosimendan enhanced right ventricular cardiac power index (0.14 +/- 0.19 to 0.18W +/- 0.12, p < .001), while pulmonary vascular resistance fell from 227.7 +/- 94.5 to 178.1 +/- 62.3 dyne x s x cm (p = .002). No significant change in central venous pressure or mean pulmonary artery pressure was observed. The observed hemodynamic improvement was sustained after the levosimendan infusion was stopped.

CONCLUSIONS

Levosimendan infusion for cardiogenic shock following acute myocardial infarction improved hemodynamic parameters of right ventricular performance. Furthermore, we describe the use of right ventricular cardiac power index as a hemodynamic parameter of right ventricular performance.

Anaesthesia and right ventricular failure

Acute right ventricular (RV) failure has until recently received relatively little attention in the cardiology, critical care or anaesthesia literature. However, it is frequently encountered in cardiac surgical cases and is a significant cause of mortality in patients with severe pulmonary hypertension who undergo non-cardiac surgery. RV dysfunction may be primarily due to impaired RV contractility, or volume or pressure overload. In these patients, an increased pulmonary vascular resistance (PVR) or a decreased aortic root pressure may lead to RV ischaemia, resulting in a rapid, downward haemodynamic spiral. The key aspects of 'RV protection' in patients who are at risk of perioperative decompensation are prevention, detection and treatment aimed at reversing the underlying pathophysiology. Minimising PVR and maintaining systemic blood pressure are of central importance in the prevention of RV decompensation, which is characterised by a rising central venous pressure and a falling cardiac output. Although there are no outcome data to support any therapeutic strategy for RV failure when PVR is elevated, the combination of inhaled iloprost or intravenous milrinone with oral sildenafil produces a synergistic reduction in PVR, while sparing systemic vascular resistance. Levosimendan is a promising new inotrope for the treatment of RV failure, although its role in comparison to older agents such as dobutamine, adrenaline and milrinone has yet to be determined. This is also the case for the use of vasopressin as an alternative pressor to noradrenaline. If all else has failed, mechanical support of the RV should be considered in selected cases.

Bench-to-bedside review: Inhaled nitric oxide therapy in adults

Nitric oxide (NO) is an endogenous mediator of vascular tone and host defence. Inhaled nitric oxide (iNO) results in preferential pulmonary vasodilatation and lowers pulmonary vascular resistance. The route of administration delivers NO selectively to ventilated lung units so that its effect augments that of hypoxic pulmonary vasoconstriction and improves oxygenation. This 'Bench-to-bedside' review focuses on the mechanisms of action of iNO and its clinical applications, with emphasis on acute lung injury and the acute respiratory distress syndrome. Developments in our understanding of the cellular and molecular actions of NO may help to explain the hitherto disappointing results of randomised controlled trials of iNO.