Perioperative pharmacological management of pulmonary hypertensive crisis during congenital heart surgery

Preoperative Sildenafil in Pediatric Patients Undergoing Congenital Heart Surgeries: A Systematic Review and Meta-Analysis

Background. Pulmonary hypertension (PH) is a common complication of congenital heart disease (CHD). With early surgical intervention, outcomes have improved over the last two decades. Persistent PH, however, may still occur following surgery. Sildenafil has been shown to be beneficial for postoperative pulmonary hypertensive crises. The role of preoperative sildenafil in controlling postoperative PH is poorly elucidated. This study aimed to evaluate the effect of preoperative sildenafil on pediatric patients undergoing congenital heart surgeries. Methods. A comprehensive literature search was conducted in scientific databases. We included randomized controlled trials which assessed the effect of preoperative sildenafil in pediatric patients with CHD undergoing repair surgeries. Primary outcomes were pre- and postoperative differences in mean pulmonary arterial pressure (mPAP) and mean pulmonary artery/aortic pressure ratio (PA/Ao ratio). Results. Four studies (n = 233) were retained for the final analysis. Dose of sildenafil ranged from .3 to .5 mg/kg every 4-6 hours via oral/nasogastric route, with timing of administration varied from 1 to 2 weeks before surgery. Compared to controls, preoperative sildenafil was associated with greater reduction in postoperative mPAP (MD -5.02; 95% CI [-8.91, -1.13]) and mean PA/Ao ratio (MD -.11; 95% CI [-.17, -.06]). Shorter CPB time, ICU length of stay, and duration of mechanical ventilation were also observed in the sildenafil group. Conclusion. Preoperative sildenafil is beneficial in reducing PAP, thereby reducing the risk of postoperative PH crisis. Further studies are warranted to identify the optimal dosage and timing of administration of sildenafil in CHD patients prior to surgery.

The efficacy of the treat-repair-treat strategy for severe pulmonary arterial hypertension associated with congenital heart disease: a meta-analysis

BACKGROUND

This meta-analysis was conducted to evaluate the efficacy of the treat-repair-treat (TRT) strategy in the treatment of severe pulmonary arterial hypertension with congenital heart disease (PAH-CHD).

METHODS

PubMed, EMBASE, Cochrane and Web of Science online databases were searched by two independent investigators for studies that used the TRT strategy for PAH-CHD, and the retrieved studies were reviewed by a third investigator. The main outcomes were pulmonary artery pressure (PAP), pulmonary vascular resistance (PVR), 6-minute walk distance (6MWD), and transcutaneous oxygen saturation (SpO2). The changes were compared between follow-up and baseline. Stata version 14.0 was used for data analysis. A random-effects model was selected for meta-analysis. Subgroup analysis and meta-regression were used to find the source of heterogeneity.

RESULTS

A total of 335 patients from 9 single-arm studies were included. Meta-analysis showed significant reductions in PAP and PVR and improvements in 6MWD and SpO2 (PAP: SMD -2.73 95% CI -2.97, - 2.50 p = < 0.001; PVR: SMD -1.27 95% CI -1.53, - 1.02 p = < 0.001; 6MWD: SMD 1.88 95% CI 1.49, 2.27 p = < 0.001; SpO2: SMD 3.72 95% CI 3.13, 4.32 p = < 0.001). Subgroup analysis showed that younger patients had better efficacy, and the change in SpO2 was an indication for patient selection. The combined mortality rate was 5% at follow-up.

CONCLUSIONS

In this meta-analysis, we demonstrated that the TRT strategy may have positive effects on haemodynamics and cardiac function in patients with severe PAH-CHD at short-term follow-up. Our analysis suggests that changes in age and SpO2 may be related to patient prognosis.

TRIAL REGISTRATION

The protocol was registered on the PROSPERO website with the registration number CRD42022366552. The relevant registration information can be obtained from the website https://www.crd.york.ac.uk/prospero/#searchadvanced .

A 1-month-old infant with pulmonary hypertensive crisis after cardiac surgery was successfully rescued with connection of left atrial and right ventricular pressure measurement tubes: a case report

Background

Pulmonary hypertensive crisis is a complication with extremely high mortality after surgery of congenital heart disease. However, there are still no treatment guidelines or expert consensus on the standard treatment of pulmonary hypertensive crisis, and the effect of conventional treatment is still unsatisfactory. We present a case of a patient who developed pulmonary hypertensive crisis after cardiac surgery, and was successfully rescued with a pioneering method, which has never been reported so far.

Case summary

An infant with congenital heart disease had undergone cardiac surgery successfully. Due to obvious myocardial oedema, sternal closure was delayed. The left atrial and right ventricular pressure monitoring tubes, both of which were connected through a triplet, were inserted into right pulmonary vein and pulmonary artery, respectively, and the triplet was in closed condition. On the night of the surgery, pulmonary hypertensive crisis occurred. Emergency bedside thoracotomy was given, and the triplet was turned on urgently to make the left atrial and right ventricular pressure monitoring tubes connected. Meantime, conventional treatment was performed. Eventually, the pulmonary hypertensive crisis was quickly relieved, and the infant was discharged 9 days later.

Discussion

The left atrial and right ventricular pressure monitoring tubes are placed intraoperatively in patients who both need delayed sternal closure and have high risk factors for pulmonary hypertensive crisis, by which could not only monitor the pressure of left atrium and right ventricle in real time but also effectively relieve the right ventricular pressure instantaneously when pulmonary hypertensive crisis occurs, as well as remedy ischaemia of systemic and coronary circulation.

Veno-Arterial Extracorporeal Membrane Oxygenation Rescue in a Patient With Pulmonary Hypertension Presenting for Revision Total Hip Arthroplasty: A Case Report and Narrative Review

Patients with pulmonary hypertension (PH) are at an increased risk of perioperative morbidity and mortality when undergoing non-cardiac surgery. We present a case of a 57-year-old patient with severe PH, who developed cardiac arrest as the result of right heart failure, undergoing a revision total hip arthroplasty under combined spinal epidural anesthesia. Emergent veno-arterial (VA) extracorporeal membrane oxygenation (ECMO) was undertaken as rescue therapy during the pulmonary hypertensive crisis and a temporizing measure to provide circulatory support in an intensive care unit (ICU). We present a narrative review on perioperative management for patients with PH undergoing non-cardiac surgery. The review goes through the updated hemodynamic definition, clinical classification of PH, perioperative morbidity, and mortality associated with PH in non-cardiac surgery. Pre-operative assessment evaluates the type of surgery, the severity of PH, and comorbidities. General anesthesia (GA) is discussed in detail for patients with PH regarding the benefits of and unsubstantiated arguments against GA in non-cardiac surgery. The literature on risks and benefits of regional anesthesia (RA) in terms of neuraxial, deep plexus, and peripheral nerve block with or without sedation in patients with PH undergoing non-cardiac surgery is reviewed. The choice of anesthesia technique depends on the type of surgery, right ventricle (RV) function, pulmonary artery (PA) pressure, and comorbidities. Given the differences in pathophysiology and mechanical circulatory support (MCS) between the RV and left ventricle (LV), the indications, goals, and contraindications of VA-ECMO as a rescue in cardiopulmonary arrest and pulmonary hypertensive crisis in patients with PH are discussed. Given the significant morbidity and mortality associated with PH, multidisciplinary teams including anesthesiologists, surgeons, cardiologists, pulmonologists, and psychological and social worker support should provide perioperative management.

Comparison of Nebulized Versus Intravenous Milrinone on Reducing Pulmonary Arterial Pressure in Patients with Pulmonary Hypertension Candidate for Open-cardiac Surgery: A Double-Blind Randomized Clinical Trial

Background

Regardless of the cause, pulmonary hypertension can increase patient complications and mortality. This study compared the effect of nebulized versus intravenous (IV) milrinone on reducing pulmonary arterial pressure in patients with pulmonary hypertension candidates for open-cardiac surgery.

Methods

This double-blind, randomized clinical trial was performed on 32 patients undergoing elective on-pump cardiac surgery during January 2021-January 2022 in the Cardiac Operating Room of Golestan Hospital, Ahvaz, Iran. Patients were randomly divided into test groups nebulize milrinone (N = 16) and IV milrinone (N = 16). The medication was administered after the cross-clamp of the aorta opening. The outcome variables included hemodynamic data, cardiac output, cardiac index, stroke volume, mean arterial pressure (MAP), central venous pressure, mean pulmonary artery pressure (mPAP), systemic vascular resistance, pulmonary vascular resistance, MAP/mPAP ratio, time until extubation, duration of hospitalization in the Intensive Care Unit (ICU), and duration of hospital stay.

Results

In the nebulized group, MAP and MAP/mPAP were significantly higher than in the IV milrinone group (P = 0.09 and P < 0.0001, respectively). The time of extubation (P = 0.001), duration of hospitalization in the ICU (P = 0.009), and duration of hospital stay (P = 0.026) in the nebulized milrinone group were significantly shorter than in the IV milrinone group.

Conclusions

Nebulized milrinone administration before weaning off cardiopulmonary bypass (CPB) can be accelerated and facilitate weaning off CPB. Moreover, despite maintaining MAP, nebulized milrinone significantly reduces mPAP. According to the results of this study, nebulized milrinone is recommended in patients undergoing cardiac surgery with pulmonary hypertension.

A systematic review of clinical study evidence for pulmonary vasodilator therapy following surgery with cardiopulmonary bypass in children with CHD

OBJECTIVES

Complications from pulmonary hypertension are one of the leading contributors to morbidity and mortality post-cardiopulmonary bypass surgery in children with CHD. Pulmonary vasodilator therapies are commonly used post-operatively, but the optimal target patient population, therapy choice, timing of therapy initiation, and duration of therapy are not well defined.

METHODS

We used PubMed and EMBASE to identify studies from 2000 to 2020 investigating the use of pulmonary vasodilator therapy post-cardiopulmonary bypass in children aged 0-18 years. To ensure eligibility criteria, studies were systematically reviewed by two independent reviewers.

RESULTS

We identified 26 studies of 42,971 children across four medication classes; 23 were single centre, 14 were prospective, and 11 involved randomisation (four of which employed a placebo-control arm). A disproportionate number of children were from a single retrospective study of 41,872 patients. Definitions varied, but change in pulmonary haemodynamics was the most common primary outcome, used in 14 studies. Six studies had clinical endpoints, with mortality the primary endpoint for two studies. Treatment with inhaled nitric oxide, iloprost, and sildenafil all resulted in improved haemodynamics in specific cohorts of children with post-operative pulmonary hypertension, although improved outcomes were not consistently demonstrated across all treated children. Iloprost may be a cheaper alternative to inhaled nitric oxide with similar haemodynamic response.

CONCLUSION

Studies were predominantly single-centre, a control arm was rarely used in randomised studies, and haemodynamic endpoints varied significantly. Further research is needed to reduce post-operative morbidity and mortality from pulmonary hypertension in children with CHD.

Anesthetic management of cesarean delivery of parturient with systemic lupus erythematosus associated with pulmonary arterial hypertension - A case report -

Background

Pulmonary hypertension in pregnancy is rare and leads to high maternal morbidity and mortality.

Case

A 27-year-old parturient woman with a 31-week gestational age underwent cesarean delivery under combined spinal-epidural anesthesia. She had systemic lupus erythematosus associated with severe pulmonary arterial hypertension. The operation was done in the cardiac theatre along with meticulous invasive monitoring. Insertion of femoral artery and femoral vein catheters for veno-arterial extracorporeal membrane oxygenation was done before delivery as preparation for the potential emergency of a life-threatening form of decompensated cardiac failure. During the delivery, the patient suddenly developed increased pulmonary arterial pressure. This was controlled by the continuous infusion of intravenous milrinone.

Conclusions

We report the successful management of this patient in the perioperative period. For cases such as that reported here, we recommend multidisciplinary team collaboration coupled with invasive cardiovascular monitoring and scrupulous anesthetic management.

Postoperative Pulmonary Hemodynamics and Systemic Inflammatory Response in Pediatric Patients Undergoing Surgery for Congenital Heart Defects

There is scarce information about the relationships between postoperative pulmonary hemodynamics, inflammation, and outcomes in pediatric patients with congenital cardiac communications undergoing surgery. We prospectively studied 40 patients aged 11 (8–17) months (median with interquartile range) with a preoperative mean pulmonary arterial pressure of 48 (34–54) mmHg who were considered to be at risk for postoperative pulmonary hypertension. The immediate postoperative pulmonary/systemic mean arterial pressure ratio (PAP/SAP_IPO, mean of first 4 values obtained in the intensive care unit, readings at 2-hour intervals) was correlated directly with PAP/SAP registered in the surgical room just after cardiopulmonary bypass (r = 0.68, p < 0.001). For the entire cohort, circulating levels of 15 inflammatory markers changed after surgery. Compared with patients with PAP/SAP_IPO ≤ 0.40 (n = 22), those above this level (n = 18) had increased pre- and postoperative serum levels of granulocyte colony-stimulating factor (p = 0.040), interleukin-1 receptor antagonist (p = 0.020), interleukin-6 (p = 0.003), and interleukin-21 (p = 0.047) (panel for 36 human cytokines) and increased mean platelet volume (p = 0.018). Using logistic regression analysis, a PAP/SAP_IPO > 0.40 and a heightened immediate postoperative serum level of macrophage migration inhibitory factor (quartile analysis) were shown to be predictive of significant postoperative cardiopulmonary events (respective hazard ratios with 95% CIs, 5.07 (1.10–23.45), and 3.29 (1.38–7.88)). Thus, the early postoperative behavior of the pulmonary circulation and systemic inflammatory response are closely related and can be used to predict outcomes in this population.

Long-Term Follow-Up of Pediatric Patients with Severe Postoperative Pulmonary Hypertension After Correction of Congenital Heart Defects

The surgical repair of congenital heart defects in children with preoperative pulmonary hypertension (PH) is to varying degree associated with the occurrence of postoperative PH. The objective of this study was to follow up children with severe postoperative PH (pulmonary arterial/aortic pressure ratio ≥ 1.0) to evaluate if pulmonary arterial pressure spontaneously normalized or needed PH-targeting therapy and to identify potential high-risk diagnoses for bad outcome. Twenty-five children who developed clinically significant severe PH on at least three occasions postoperatively were included in the follow-up (20-24 years). Data from chart reviews, echocardiographic investigations, and questionnaires were obtained. Three children died within the first year after surgery. Three children were lost to follow-up. The remaining 17 children normalized their pulmonary arterial pressure without the use of PH-targeting drugs at any time during the follow-up. Two children had a remaining mild PH with moderate mitral valve insufficiency. All three children with bad outcome had combined cardiac lesions causing post-capillary pulmonary hypertension. Normalization of the pulmonary arterial pressure occurred in almost all children with severe postoperative PH, without any need of supplemental PH-targeting therapies. All children with bad outcome had diagnoses conformable with post-capillary PH making the use of PH-targeting therapies relatively contraindicated. These data emphasize the need to perform randomized, blinded trials on the use of PH-targeting drugs in children with postoperative PH before accepting it as an indication for routine treatment.

Perioperative Management of Pulmonary Hypertension. a Review

Pulmonary hypertension is a rare and progressive pathology defined by abnormally high pulmonary artery pressure mediated by a diverse range of aetiologies. It affects up to twenty-six individuals per one million patients currently living in the United Kingdom (UK), with a median life expectancy of 2.8 years in idiopathic pulmonary hypertension. The diagnosis of pulmonary hypertension is often delayed due to the presentation of non-specific symptoms, leading to a delay in referral to specialists services. The complexity of treatment necessitates a multidisciplinary approach, underpinned by a diverse disease aetiology from managing the underlying disease process to novel specialist treatments. This has led to the formation of dedicated specialist treatment centres within centralised UK cities. The article aimed to provide a concise overview of pulmonary hypertension’s clinical perioperative management, including key definitions, epidemiology, pathophysiology, and risk stratification.

Nitroglycerin inhalation for acute treatment of pulmonary arterial hypertension in children with congenital heart disease

OBJECTIVES

Acute pulmonary hypertension and pulmonary hypertensive crisis may result in adverse clinical outcomes if unsuccessfully treated. Inhaled nitric oxide has long been considered as the standard pharmacotherapy for acute pulmonary hypertension, but lack of feasibility in some settings and evidences challenging its benefits lead to the use of alternative treatment, amongst which is nitroglycerin inhalation. The purpose of this review article is to discuss available data on the use of nitroglycerin inhalation for acute treatment of pulmonary hypertension in children with CHD and its potential benefit in post-operative setting.

DATA SOURCES

Literatures included in this review were acquired by searching in PubMed online database. Keywords used were "Pulmonary Hypertension", "Congenital heart defects", "Pediatrics", "Inhaled nitroglycerin", and its synonyms.

STUDY SELECTION

Title and abstract were screened to select relevant literatures including the three paediatric clinical trials on nitroglycerin inhalation. Critical appraisal of the clinical trials was then done using the University of Oxford Centre of Evidence-Based Medicine Critical Appraisal Tools.

CONCLUSIONS

Paediatric studies showed the benefit of nitroglycerin inhalation in uncorrected cases of CHD during catheterisation procedures. Until recently, there have been no studies conducted in paediatric post-operative CHD cases. Further study is required to provide evidence for inhaled nitroglycerin use in this setting including the appropriate dosing and potential side effects with repeated administration.

Variability in the Physiologic Response to Fluid Bolus in Pediatric Patients Following Cardiac Surgery

BACKGROUND

Fluid boluses aiming to improve the cardiac output and oxygen delivery are commonly administered in children with shock. An increased mean arterial pressure in addition to resolution of tachycardia and improved peripheral perfusion are often monitored as clinical surrogates for improvement in cardiac output. The objective of our study is to describe changes in cardiac index, mean arterial pressure, and their relationship to other indices of cardiovascular performance.

OBJECTIVE

The objective of our study is to describe changes in cardiac index, mean arterial pressure, and their relationship to other indices of cardiovascular performance.

DESIGN, SETTING, PATIENTS, AND INTERVENTIONS

We prospectively analyzed hemodynamic data from children in the cardiac ICU who received fluid bolus (10mL/kg of Ringers-Lactate over 30 min) for management of shock and/or hypoperfusion within 12h of cardiac surgery. Cardiac index responders and mean arterial pressure-responders were defined as CI ≥10% and mean arterial pressure ≥10%, respectively. We evaluated the gradient for venous-return (mean systemic filling pressure-central venous pressure), arterial load properties (systemic vascular resistance index and elastance index) and changes in vasopressor support after fluid bolus.

MEASUREMENTS AND MAIN RESULTS

Fifty-seven children between 1 month and 16 years (median Risk adjustment after congenital heart surgery Model for Outcome Surveillance in Australia and New Zealand score of 3.8 (interquartile range 3.7-4.6) received fluid bolus. Cardiac index-responsiveness and mean arterial pressure-responsiveness rates were 33% and 56%, respectively. No significant correlation was observed between changes in mean arterial pressure and cardiac index (r = 0.035, p = 0.79). Although the mean systemic filling pressure - central venous pressure and the number of cardiac index-responders after fluid bolus were similar, the arterial load parameters did not change in mean arterial pressure-nonresponders. Forty-three patients (75%) had a change in Vasoactive-Inotrope Score after the fluid bolus, of whom 60% received higher level of vasoactive support.

CONCLUSIONS

The mean arterial pressure response to fluid bolus in cardiac ICU patients was unpredictable with a poor relationship between cardiac index-responsiveness and mean arterial pressure-responsiveness. Because arterial hypotension is frequently a trigger for administering fluids and changes in blood pressure are commonly used for tracking changes in cardiac output, we suggest a cautious and individualized approach to repeat fluid bolus based solely on lack of mean arterial pressure response to the initial fluid, since the implications include decreased arterial tone even if the cardiac index increases.

Survival of Left-to-Right Shunt Repair in Children with Pulmonary Arterial Hypertension at a Tertiary Hospital in a Low-to-Middle-Income Country

Background

In low-to-middle-income countries, repair of the left-to-right shunts congenital heart disease (CHD) are often done with existing pulmonary arterial hypertension (PAH). Long-term outcomes data of this condition in either low-to-middle or high-income countries are limited. We conducted a study to evaluate the outcomes of children with PAH related to left-to-right shunt CHD who underwent surgical or transcatheter repair.

Methods

All cases of PAH related to left-to-right shunt CHD repairs from 2015-2018 were retrospectively reviewed with additional new patients who underwent repair within our study period (2019-2020). Cases with complex congenital heart disease and incomplete hemodynamic echocardiography or catheterization measurements were excluded. Kaplan-Meier curves, log-rank test, Cox regression with Firth's correction and restricted mean survival time were used for survival analysis.

Results

Of the 118 patients, 103 patients were enrolled and 15 patients were excluded due to complex congenital heart disease and missing hemodynamic measurements prior to repair. Overall, median age at intervention was 44 months, mPAP mean was 43.17 ± 16.05 mmHg and Pulmonary Vascular Resistance index (PVRi) mean was 2.84 ± 2.09 (WU.m2). Nine patients died after repair. The survival rate for patients with PAH-CHD at 1 day, 30 days and 1400 days (4 years) was 96.1%, 92.1%, and 91.0% respectively. Patients with persisting PAH after correction had -476.1 days (95% confidence interval [CI]: -714.4, -237,8) shorter survival over 4 years of follow up compared to patients with reversed PAH. PVRi was found to be the influencing covariate of the difference of restricted mean survival time between these groups.

Conclusion

In low-to-middle income settings, with accurate PAH reversibility assessment prior to intervention, repair of left-to-right shunt CHD with existing PAH in children has a favourable outcome. Inferior survival is found in patients with persistence of PAH. PVRi at baseline predicts between-group survival difference.

Effect of High-Flow Nasal Cannula Oxygen Therapy on Pediatric Patients With Congenital Heart Disease in Procedural Sedation: A Prospective, Randomized Trial

OBJECTIVES

The study was conducted to compare the outcome of high-flow nasal cannula (HFNC) oxygen therapy with conventional oxygen therapy through a simple oxygen mask for pediatric patients with congenital heart disease during percutaneous intervention while under procedural sedation.

DESIGN

Prospective, randomized and controlled trial.

SETTING

A Cantonese cardiac center in China.

PARTICIPANTS

Two hundred American Society of Anesthesiologists classification II pediatric patients were enrolled from April 25, 2018 to November 28, 2018.

INTERVENTIONS

Patients scheduled for percutaneous closure of a heart defect under deep sedation with propofol, midazolam and fentanyl by an anesthesiologist were randomized (1:1) to receive oxygen therapy through a simple oxygen mask or through the HFNC system.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was the lowest oxygen saturation (SpO₂). Secondary outcomes included the incidence of hypoxia (SpO₂ < 90%), requirement for noninvasive respiratory support, change in the gastric antrum area and other adverse events. Blood gas analysis results also were compared. Oxygen therapy through the HFNC system improved the lowest SpO₂ (99% [94%-100%]), as compared with the mask group (99% [72%-100%]), p < 0.001. Seven patients out of 99 (7.1%) in the mask group had hypoxia or required bag-mask ventilation, whereas no such patient was reported in the HFNC group, p < 0.001. There were no differences between the groups in terms of gastric distention, procedure length, total propofol dose, atropine use or other complications.

CONCLUSION

When compared with simple mask oxygenation, HFNC could reduce the incidence of desaturation, the need for airway assisted ventilation and risk of carbon dioxide retention without causing hemodynamic instability or gastric distention. It is effective for pediatric patients with non-cyanotic congenital heart disease who require procedural sedation.

Spectrum of Current Management of Pediatric Pulmonary Hypertensive Crisis

Pulmonary hypertension is a growing pediatric problem and children may present with pulmonary hypertensive crisis-a life-threatening emergency requiring acute interventions. The aim of this study was to characterize the broad spectrum of care provided in North American PICUs for children who present with pulmonary hypertensive crisis.

DESIGN

Electronic cross-sectional survey. Survey questions covered the following: demographics of the respondents, institution, and patient population; pulmonary hypertension diagnostic modalities; pulmonary hypertension-specific pharmacotherapies; supportive therapies, including sedation, ventilation, and inotropic support; and components of multidisciplinary teams.

SETTING

PICUs in the United States and Canada.

SUBJECTS

Faculty members from surveyed institutions.

INTERVENTIONS

None.

MEASUREMENT AND MAIN RESULTS

The response rate was 50% of 99 identified institutions. Of the respondents, 82.2% were pediatric intensivists from large units, and 73.9% had over a decade of experience beyond training. Respondents provided care for a median of 10 patients/yr with acute pulmonary hypertensive crisis. Formal echocardiography protocols existed at 61.1% of institutions with varying components reported. There were no consistent indications for cardiac catheterization during a pulmonary hypertensive crisis admission. All institutions used inhaled nitric oxide, and enteral phosphodiesterase type 5 inhibitor was the most frequently used additional targeted vasodilator therapy. Milrinone and epinephrine were the most frequently used vasoactive infusions. Results showed no preferred approach to mechanical ventilation. Fentanyl and dexmedetomidine were the preferred sedative infusions. A formal pulmonary hypertension consulting team was reported at 51.1% of institutions, and the three most common personnel were pediatric cardiologist, pediatric pulmonologist, and advanced practice nurse.

CONCLUSIONS

The management of critically ill children with acute pulmonary hypertensive crisis is diverse. Findings from this survey may inform formal recommendations - particularly with regard to care team composition and pulmonary vasodilator therapies - as North American guidelines are currently lacking. Additional work is needed to determine best practice, standardization of practice, and resulting impact on outcomes.

Effects of vasopressin during a pulmonary hypertensive crisis induced by acute hypoxia in a rat model of pulmonary hypertension

BACKGROUND

A pulmonary hypertensive crisis (PHC) can be a life-threatening condition. We established a PHC model by exposing rats with monocrotaline (MCT)-induced pulmonary hypertension to acute hypoxia, and investigated the effects of vasopressin, phenylephrine, and norepinephrine on the PHC.

METHODS

Four weeks after MCT 60 mg kg^-1 administration i.v., right ventricular systolic pressure (RVSP), systolic BP (SBP), mean BP (MBP), cardiac index (CI), and pulmonary vascular resistance index (PVRI) were measured. PHC defined as an RVSP exceeding or equal to SBP was induced by changing the fraction of inspiratory oxygen to 0.1. Rats were subsequently treated by vasopressin, phenylephrine, or norepinephrine, followed by assessment of systemic haemodynamics, isometric tension of femoral and pulmonary arteries, cardiac function, blood gas composition, and survival.

RESULTS

PHC was associated with increased RV dilatation and paradoxical septal motion. Vasopressin increased MBP [mean (standard error)] from 52.6 (3.8) to 125.0 (8.9) mm Hg and CI from 25.4 (2.3) to 40.6 (1.8) ml min^-1 100 g^-1 while decreasing PVRI. Vasopressin also improved RV dilatation, oxygenation, and survival in PHC. In contrast, phenylephrine increased MBP from 54.8 (2.3) to 96.8 (3.2) mm Hg without improving cardiac pump function. Norepinephrine did not alter MBP. Vasopressin contracted femoral but not pulmonary arteries, whereas phenylephrine contracted both arterial beds. Hence, improvements with vasopressin in PHC might be associated with decreased PVRI and selective systemic vasoconstriction.

CONCLUSIONS

In this rat model of a PHC, vasopressin, but not phenylephrine or norepinephrine, resulted in better haemodynamic and vascular recovery.

Metabolic Response of the Immature Right Ventricle to Acute Pressure Overloading

BACKGROUND

Surgical palliation or repair of complex congenital heart disease in early infancy can produce right ventricular (RV) pressure overload, often leading to acute hemodynamic decompensation. The mechanisms causing this acute RV dysfunction remain unclear. We tested the hypothesis that the immature right ventricle lacks the ability to modify substrate metabolism in order to meet increased energy demands induced by acute pressure overloading.

METHODS AND RESULTS

Twenty-two infant male mixed breed Yorkshire piglets were randomized to a sham operation (Control) or pulmonary artery banding yielding >2-fold elevation over baseline RV systolic pressure. We used carbon 13 (¹³C)-labeled substrates and proton nuclear magnetic resonance to assess RV energy metabolism. [Phosphocreatine]/[ATP] was significantly lower after pulmonary artery banding. [Phosphocreatine]/[ATP] inversely correlated with energy demand indexed by maximal sustained RV systolic pressure/left ventricular systolic pressure. Fractional contributions of fatty acids to citric acid cycle were significantly lower in the pulmonary artery banding group than in the Control group (medium-chain fatty acids; 14.5±1.6 versus 8.2±1.0%, long-chain fatty acids; 9.3±1.5 versus 5.1±1.1%). ¹³C-flux analysis showed that flux via pyruvate decarboxylation did not increase during RV pressure overloading.

CONCLUSIONS

Acute RV pressure overload yielded a decrease in [phosphocreatine]/[ATP] ratio, implying that ATP production did not balance the increasing ATP requirement. Relative fatty acids oxidation decreased without a reciprocal increase in pyruvate decarboxylation. The data imply that RV inability to adjust substrate oxidation contributes to energy imbalance, and potentially to contractile failure. The data suggest that interventions directed at increasing RV pyruvate decarboxylation flux could ameliorate contractile dysfunction associated with acute pressure overloading.

Hemodynamic Effects of Phenylephrine, Vasopressin, and Epinephrine in Children With Pulmonary Hypertension: A Pilot Study

OBJECTIVES

During a pulmonary hypertensive crisis, the marked increase in pulmonary vascular resistance can result in acute right ventricular failure and death. Currently, there are no therapeutic guidelines for managing an acute crisis. This pilot study examined the hemodynamic effects of phenylephrine, arginine vasopressin, and epinephrine in pediatric patients with pulmonary hypertension.

DESIGN

In this prospective, open-label, nonrandomized pilot study, we enrolled pediatric patients previously diagnosed with pulmonary hypertensive who were scheduled electively for cardiac catheterization. Primary outcome was a change in the ratio of pulmonary-to-systemic vascular resistance. Baseline hemodynamic data were collected before and after the study drug was administered.

PATIENTS

Eleven of 15 participants were women, median age was 9.2 years (range, 1.7-14.9 yr), and median weight was 26.8 kg (range, 8.5-55.2 kg). Baseline mean pulmonary artery pressure was 49 ± 19 mm Hg, and mean indexed pulmonary vascular resistance was 10 ± 5.4 Wood units. Etiology of pulmonary hypertensive varied, and all were on systemic pulmonary hypertensive medications.

INTERVENTIONS

Patients 1-5 received phenylephrine 1 μg/kg; patients 6-10 received arginine vasopressin 0.03 U/kg; and patients 11-15 received epinephrine 1 μg/kg. Hemodynamics was measured continuously for up to 10 minutes following study drug administration.

MEASUREMENTS AND MAIN RESULTS

After study drug administration, the ratio of pulmonary-to-systemic vascular resistance decreased in three of five patients receiving phenylephrine, five of five patients receiving arginine vasopressin, and three of five patients receiving epinephrine. Although all three medications resulted in an increase in aortic pressure, only arginine vasopressin consistently resulted in a decrease in the ratio of systolic pulmonary artery-to-aortic pressure.

CONCLUSIONS

This prospective pilot study of phenylephrine, arginine vasopressin, and epinephrine in pediatric patients with pulmonary hypertensive showed an increase in aortic pressure with all drugs although only vasopressin resulted in a consistent decrease in the ratio of pulmonary-to-systemic vascular resistance. Studies with more subjects are warranted to define optimal dosing strategies of these medications in an acute pulmonary hypertensive crisis.

Does intravenous sildenafil clinically ameliorate pulmonary hypertension during perioperative management of congenital heart diseases in children? - a prospective randomized study

BACKGROUND

Pulmonary hypertension (PHT), if present, can be a significant cause of increased morbidity and mortality in children undergoing surgery for congenital heart diseases (CHD). Various techniques and drugs have been used perioperatively to alleviate the effects of PHT. Intravenous (IV) sildenafil is one of them and not many studies validate its clinical use.

AIMS AND OBJECTIVES

To compare perioperative PaO 2 - FiO 2 ratio peak filling rate (PFR), systolic pulmonary artery pressure (PAP) - systolic aortic pressure (AoP) ratio, extubation time, and Intensive Care Unit (ICU) stay between two groups of children when one of them is administered IV sildenafil perioperatively during surgery for CHDs.

MATERIALS AND METHODS

Patients with ventricular septal defects and proven PHT, <14 years of age, all American Society of Anesthesiologists physical status III, undergoing cardiac surgery, were enrolled into two groups - Group S (IV sildenafil) and Group C (control) - over a period of 14 months, starting from October 2013. Independent t-test and Mann-Whitney U-test were used to compare the various parameters between two groups.

RESULTS

PFR was higher throughout, perioperatively, in Group S. PAP/AoP was 0.3 and 0.4 in Group S and Group C, respectively. In Group S, mean group extubation time was 7 ± 7.34 h, whereas in Group C it was 22.1 ± 10.6. Postoperative ICU stay in Group S and Group C were 42.3 ± 8.8 h and 64.4 ± 15.9 h, respectively.

CONCLUSION

IV sildenafil, when used perioperatively, in children with CHD having PHT undergoing corrective surgery, improves not only PaO 2 - FiO 2 ratio and PAP - AoP ratio but also reduces extubation time and postoperative ICU stay.

Perioperative Considerations for Children With Right Ventricular Dysfunction and Failing Fontan

The survival of patients with congenital heart diseases (CHD) has increased in the past decades, resulting in the identification of new characteristics of chronic comorbidities observed in pediatric and adults with CHD. Patients with CHD can present with a broad clinical spectrum of manifestations of congestive heart failure (CHF) at any point throughout their lives that may be related to anatomical or surgical variables. This article focuses on the perioperative assessment of patients with CHD and CHF, with an emphasis on pathophysiologic, diagnostic, and therapeutic alternatives in patients with right ventricular failure and failing Fontan circulation. We also provide descriptions of the effects of sedatives and anesthetics commonly used in this population in diagnostic or invasive procedures.

Modulation of miRNAs in Pulmonary Hypertension

MicroRNAs (miRNAs) have emerged as a new class of posttranscriptional regulators of many cardiac and vascular diseases. They are a class of small, noncoding RNAs that contributes crucial roles typically through binding of the 3′-untranslated region of mRNA. A single miRNA may influence several signaling pathways associated with cardiac remodeling by targeting multiple genes. Pulmonary hypertension (PH) is a rare disorder characterized by progressive obliteration of pulmonary (micro) vasculature that results in elevated vascular resistance, leading to right ventricular hypertrophy (RVH) and RV failure. The pathology of PH involves vascular cell remodeling including pulmonary arterial endothelial cell (PAEC) dysfunction and pulmonary arterial smooth muscle cell (PASMC) proliferation. There is no cure for this disease. Thus, novel intervention pathways that govern PH induced RVH may result in new treatment modalities. Current therapies are limited to reverse the vascular remodeling. Recent studies have demonstrated the roles of various miRNAs in the pathogenesis of PH and pulmonary disorders. This review provides an overview of recent discoveries on the role of miRNAs in the pathogenesis of PH and discusses the potential for miRNAs as therapeutic targets and biomarkers of PH at clinical setting.