Ostium Of Coronary Artery Research Articles

P233 ACUTE CORONARY SYNDROME AFTER WASP BITE (KOUNIS SYNDROME)

Abstract Kounis syndrome (KS) is defined as an acute coronary syndrome (SCA) associated with an anaphylactic reaction. A 64–year–old sports man with no previous cardiovascular disease arrived at the emergency room of our Hospital for dyspnoea and chest pain arising during physical activity e preceded by a syncopal episode. During the physical activity (cycling) the patient reported that he had felt an insect bite sensation, with no possibility of precisely identify it. Parameters an admission were: BP 85/45 mmHg, HR 70 bpm, on ECG signs of early repolarization (Fig. 1), blood tests rise in hsTNI (328 ng/L), normal D–dimer. The transthoracic echocardiogram showed no motion abnormalities. In the suspicion of KS, therapy was set up only with ASA and statin, avoiding any drug commonly used to treat allergic reactions that could have worsen the hemodynamic and vasomotor situation by further reducing the coronary perfusion. During hospitalization, in consideration of the clinical picture and cardiovascular risk factors (dyslipidemia and previous smoking), was performed coronary angiography, which showed no obstructive lesions, but during the first injection of contrast showed vasospasm of the ostium of the right coronary artery, dominant (Fig. 2 – left), resolved spontaneously (Fig. 2 – right). The post–procedural hsTNI peak (3953 ng/L) and the presence of the European paper wasp i77 antigen to the serological dosage of the allergens supported the pathophysiology of acute coronary syndrome concomitant with allergic reaction and supported the diagnostic hypothesis of KS type I (without underlying coronary artery disease). The patient was discharged with calcium channel blocker therapy, to reduce coronary vasospasm which characterizes KS, and short–term follow–up was planned with blood tests, exercise stress test and cardiological visit which were normal. KS, though rare, is a clinical entity that should not be underestimated, especially in allergic patients with evidence of SCA without coronary occlusions. The data available in the literature are scarce and it is not clear the medium and long term prognosis. It therefore seems reasonable to follow up the patients as outpatient cardiology visits especially in the first months after the event and schedule instrumental tests control.

Abstract 128: Safety And Efficacy Of Pro-efferocytic Nanoparticles To Treat Atherosclerosis In A Porcine Model

Background and Aims: Within the atherosclerotic plaque, the formation of a necrotic core is, in part, a consequence of impaired macrophage efferocytosis in which apoptotic vascular cells upregulate “don’t-eat-me,” anti-phagocytic ligand CD47. In vivo , translational murine model studies demonstrating off-target effects of anti-CD47 antibody-mediated blockade prompted the development and successful validation of a macrophage-specific nanotherapy loaded with a chemical inhibitor of Src homology 2 domain-containing phosphatase-1 (SHP-1), a small molecule downstream of the CD47-SIRPα signaling axis. We aimed to test the safety and efficacy of this SHP-1 inhibitor nanotherapy in preventing atherosclerosis in a pre-clinical porcine model. Methods and Results: Sixteen LDLR -/- pigs were fed an atherogenic diet and treated with single-walled carbon nanotubes (SWNT) loaded with SHP1 inhibitor (SWNT-SHP1i) (n=8) or with SWNT alone (n=8), dosed weekly for three months. Blood samples were collected at baseline and at monthly intervals. The lipid panel, CMP, and CBC demonstrated no significant difference between the SWNT-SHP1i and control treatment groups at each timepoint. Survey of major arterial beds by histology revealed early-stage fatty streak disease within the left and right coronary artery (RCA) ostium in addition to the abdominal aorta distal to the renal arteries. Pigs underwent PET/CT in the final week of treatment. The SWNT-SHP1i treated cohort displayed a reduced carotid artery uptake of 18F-FDG compared to the controls (p = 0.017). Bulk RNA sequencing analysis of the carotid artery demonstrated multiple differentially expressed pathways related to hemostasis and the immune response. Conclusion: In a porcine model, macrophage-specific SWNT-SHP1i treatment is not significantly associated with anemia, thus circumventing off-target effects of global anti-CD47 blockade. PET/CT reveals evidence of significantly decreased vascular inflammation in the carotid arteries in the SWNT-SHP1i treated cohort. Bulk RNA-seq confirms numerous significant differentially expressed genes. Ongoing blinded, quantitative histological analysis will further compare both plaque burden and plaque M1/M2 macrophage content between the two cohorts.

B-33 | Orbital Atherectomy for Calcified Ostial Coronary Artery Disease: A Single-Center Experience

B-33 | Orbital Atherectomy for Calcified Ostial Coronary Artery Disease: A Single-Center Experience

Coronary Obstruction during Valve-in-Valve Transcatheter Aortic Valve Replacement: Pre-Procedural Risk Evaluation, Intra-Procedural Monitoring, and Follow-Up.

Valve-in-valve (ViV) transcatheter aortic valve replacement (TAVR) is emerging as an effective treatment for patients with symptomatically failing bioprosthetic valves and a high prohibitive surgical risk; a longer life expectancy has led to a higher demand for these valve reinterventions due to the increased possibilities of outliving the bioprosthetic valve's durability. Coronary obstruction is the most feared complication of valve-in-valve (ViV) TAVR; it is a rare but life-threatening complication and occurs most frequently at the left coronary artery ostium. Accurate pre-procedural planning, mainly based on cardiac computed tomography, is crucial to determining the feasibility of a ViV TAVR and to assessing the anticipated risk of a coronary obstruction and the eventual need for coronary protection measures. Intraprocedurally, the aortic root and a selective coronary angiography are useful for evaluating the anatomic relationship between the aortic valve and coronary ostia; transesophageal echocardiographic real-time monitoring of the coronary flow with a color Doppler and pulsed-wave Doppler is a valuable tool that allows for a determination of real-time coronary patency and the detection of asymptomatic coronary obstructions. Because of the risk of developing a delayed coronary obstruction, the close postprocedural monitoring of patients at a high risk of developing coronary obstructions is advisable. CT simulations of ViV TAVR, 3D printing models, and fusion imaging represent the future directions that may help provide a personalized lifetime strategy and tailored approach for each patient, potentially minimizing complications and improving outcomes.

Absent Right Coronary Artery in an Active Young Female

Absent Right Coronary Artery in an Active Young Female

Clinical Results of a Modified Doty’s Technique for Supravalvular Aortic Stenosis

This study aimed to assess the early and mid-term results of the modified Doty's technique compared with the traditional Doty's technique in patients with congenital supravalvular aortic stenosis (SVAS). We retrospectively included 73 consecutive SVAS patients in Beijing and Yunnan Fuwai Hospitals between 2014 and 2021. Patients were divided into the modified technique (n = 9) and the traditional technique group (n = 64). The modified technique involves altering the right head of the symmetrical inverted pantaloon-shaped patch into an asymmetrical triangular form to prevent compression of the right coronary artery ostium. The primary safety outcome was in-hospital surgery-related complications and the primary effectiveness outcome was re-operation at follow-up. The Mann-Whitney U test and Fisher's exact test were used to test the group difference. The median age at operation was 50 months (IQR 27.0-96.0). Twenty-two (30.1%) of the patients were female. The median follow-up was 23.5 months (IQR 3.0-46.0). No in-hospital surgery-related complications and follow-up re-operation occurred in the modified technique group, but the traditional technique group had 14 (21.8%) surgery-related complications and 5 (7.9%) re-operation. Patients with the modified technique had a well-developed aortic root and no aortic regurgitation occurred. A modified technique could be considered for patients with poor aortic root development to reduce postoperative surgery-related complications.

Answer: Uncommon masquerader of inferior STEMI.

Correct answer: 2. Aortic Dissection JR-4 guide into aortic root with non-selective shot suggest aortic dissection—filling the right coronary artery therefore in the false lumen (see Supplementary material online, Video S1 and Figure 1B, arrow indicates right coronary artery). Acute Type A aortic dissection is then confirmed with pigtail aortogram where the true lumen is shown and filling the left main artery (see Supplementary material online, Video S2 and Figure 1C, arrow indicates dissection flap). Glyceryl trinitrate infusion was started with gradual titration for his hypertension. Patient was transferred to a cardiothoracic centre but unfortunately arrested on the computed tomography table before he could be operated. ... Myocardial infarction resulted from functional coronary artery occlusion where the dissection flap occluded the ostium of right coronary artery in this case. Invasive aortography remains a valuable tool for rapid and accurate diagnosis of aortic dissection particularly in patients presenting with ST-elevation myocardial infarction.

Coronary Obstruction From TAVR in Native Aortic Stenosis: Development and Validation of Multivariate Prediction Model

BackgroundTranscatheter aortic valve replacement (TAVR)–related coronary artery obstruction prediction remains unsatisfactory despite high mortality and novel preventive therapies. ObjectivesThis study sought to develop a predictive model for TAVR-related coronary obstruction in native aortic stenosis. MethodsPreprocedure computed tomography and fluoroscopy images of patients in whom TAVR caused coronary artery obstruction were collected. Central laboratories made measurements, which were compared with unobstructed patients from a single-center database. A multivariate model was developed and validated against a 1:1 propensity-matched subselection of the unobstructed cohort. ResultsSixty patients with angiographically confirmed coronary obstruction and 1,381 without obstruction were included. In-hospital death was higher in the obstruction cohort (26.7% vs 0.7%; P < 0.001). Annular area and perimeter, coronary height, sinus width, and sinotubular junction height and width were all significantly smaller in the obstructed cohort. Obstruction was most common on the left side (78.3%) and at the level of the coronary artery ostium (92.1%). Coronary artery height and sinus width, but not annulus area, were significant risk factors for obstruction by logistic regression but performed poorly in predicting obstruction. The new multivariate model (coronary obstruction IF cusp height > coronary height, AND virtual valve-to-coronary distance ≤4 mm OR culprit leaflet calcium volume >600 mm3) performed well, with an area under the curve of 0.93 (sensitivity = 0.93, specificity = 0.84) for the left coronary artery and 0.94 (sensitivity = 0.92, specificity = 0.96) for the right. ConclusionsA novel computed tomography–based multivariate prediction model that can be implemented routinely in real-world practice predicted coronary artery obstruction from TAVR in native aortic stenosis.

Validation and clinical impact of novel pericoronary adipose tissue measurement on ECG-gated non-contrast chest CT

Background and aimsWe aimed to develop a method for quantifying pericoronary adipose tissue (PCAT) on electrocardiogram (ECG)-gated non-contrast CT (NC-PCAT) and validate its efficacy and prognostic value. MethodsWe retrospectively studied two independent cohorts. PCAT was quantified conventionally. NC-PCAT was defined as the mean CT value of epicardial fat tissue adjacent to right coronary artery ostium on ECG-gated non-contrast CT. In cohort 1 (n = 300), we evaluated the correlation of two methods and the association between NC-PCAT and CT-verified high-risk plaque (HRP). We dichotomized cohort 2 (n = 333) by the median of NC-PCAT, and assessed the prognostic value of NC-PCAT for primary endpoint (all-cause death and non-fatal myocardial infarction) by Cox regression analysis. The median duration of follow-up was 2.9 years. ResultsNC-PCAT was correlated with PCAT (r = 0.68, p<0.0001). In multivariable logistic regression analysis, high NC-PCAT (OR:1.06; 95%CI:1.03–1.10; p = 0.0001), coronary artery calcium score (CACS) (OR:1.01 per 10 CACS increase, 95%CI:1.00–1.02; p = 0.013), and current smoking (OR:2.58; 95%CI:1.03–6.49; p = 0.044) were independent predictors of HRP. Among patients with CACS>0 (n = 193), NC-PCAT (OR:1.06; 95%CI:1.03–1.10; p = 0.0002), current smoking (OR:3.02; 95%CI:1.17–7.82; p = 0.027), and male sex (OR:2.81; 95%CI:1.06–7.48; p = 0.028) were independent predictors of HRP, whereas CACS was not (p = 0.15). Multivariable Cox regression analysis revealed high NC-PCAT as an independent predictor of the primary endpoint, even after adjustment for sex and age (HR:4.3; 95%CI:1.2–15.2; p = 0.012). ConclusionsThere was a positive correlation between NC-PCAT and PCAT, with high NC-PCAT significantly associated with worse clinical outcome (independent of CACS) as well as presence of HRP.

Intramural course of an anomalous left coronary artery is not always associated with a slit-like ostium.

Anomalous aortic origin of the left coronary artery from an incorrect aortic sinus has been reported as the second most common causes of sudden cardiac arrest in young athletes. Intramural course of the proximal left coronary artery is considered a high-risk morphology. It is associated with a slit-like ostium and elliptical shape of the proximal artery. In this case, all pre-operative cardiac images demonstrated a round ostium and round luminal shape of the left coronary artery, which suggested no evidence of intramural course. On intraoperative inspection, although the ostium and proximal left coronary artery appeared round, the patient had a long intramural course of the left coronary artery which our surgeons performed a successful unroofing procedure. The post-operative images showed a patent new ostium from the correct aortic sinus. These findings are very unusual and proved that we should not exclude intramural course even in the absence of a slit-like ostium and elliptical shape of the proximal left coronary artery.

Right Coronary Artery Origin from Left Sinus of Valsalva with an Inter-arterial Course: Case Report and Review of Literature

Introduction: Overally the anomaly of the coronary arteries are rare. Its incidence according to angiographic, autopsy and echocardiographic findings, are about 1%, 0.29% and less than 0.1% respectively. Usually these are the incidental finding during angiography without clinical presentation. These anomalies may be accompanied by myocardial ischemia, arrhythmia, syncope and sudden death. Case Presentation: We present a 14-year-old Iranian boy who experienced chest pain and shortness of breath after engaging in physical activity. The right coronary artery (RCA) had an intramural and inter-arterial course and was proven to have originated from the left sinus of Valsalva by computed tomographic coronary angiography (CTCA). The RCA began adjunct to the ostium of the left main coronary artery and coursed intramural at first and then continued between the aorta and pulmonary artery. The patient underwent corrective surgery. The RCA was cut from origin and reanastomosd to the right coronary sinus after preparing the sinus. The patient recovered well and he was discharged with the ability to perform sports activity. One year Follow up of the patient was uneventful. Conclusions: Even though single ostium coronary artery abnormalities are uncommon, they have become more frequently identified in recent years using non-invasive techniques such transthoracic echocardiography, which is then followed by CT angiography or conventional angiography. These patients are susceptible to sudden death, so attention to symptoms of the patients and comprehensive approach to them can be lifesaving.

MORPHOMETRIC AND MORPHOLOGICAL ASSESSMENT OF CORONARY ARTERIES WITH INTRAVASCULAR ULTRASOUND

The aim: To perform a morphometric assessment of the coronary arteries ostia by intravascular ultrasound with morphological evaluation among the Ukrainian population. Materials and methods: Intravascular images of the ostia of the right (48%) and left (52%) coronary arteries with the minimum diameter, maximum diameter, mean diameter and lumen area were analyzed. An intravascular ultrasound procedure was performed before percutaneous intervention. Results: A total of 25 IVUS examinations were collected from patients of both sexes and the same ages: 61,27±10,24 for males and females 68±5,83 (p=0.64).The left coronary artery (LCA) ostium assessment was performed in 13 (52%) cases: 8 men and 5 women (32% and 20%, respectively). The right coronary artery (RCA) ostium assessment was performed in 12 (48%) cases: 7 men and 5 women (28% and 20%, respectively). The maximal diameter of the coronary artery ostia was higher in men (5.95±0.66mm) than in women (4.82±0.34mm) (p<0.0001). In men, the maximal diameter of the RCA was higher than in the LCA (6.4±0.40mm and 5.56±0.60mm, respectively). The same differences were found in the mean diameter and lumen area (p<0.05). In women, the minimum diameter, mean diameter, maximum diameter and lumen area of the RCA were higher than LCA but without statistically signi#cant di"erences. The anatomic precondition explains the observed changes in echogenicity. Conclusions: IVUS analysis shows signi#cantly higher parameters of the minimum diameter, mean diameter, maximum diameter and lumen area in men than in women among the Ukrainian population. Therefore, morphological evaluation is crucial in the interpretation of intracoronary images.

Early In-Stent Restenosis of Right Coronary Artery Ostium by Calcified Nodule

Early In-Stent Restenosis of Right Coronary Artery Ostium by Calcified Nodule

Continuous extraction of coronary artery centerline from cardiac CTA images using a regression-based method.

Coronary artery centerline extraction in cardiac computed tomography angiography (CTA) is an effectively non-invasive method to diagnose and evaluate coronary artery disease (CAD). The traditional method of manual centerline extraction is time-consuming and tedious. In this study, we propose a deep learning algorithm that continuously extracts coronary artery centerlines from CTA images using a regression method. In the proposed method, a CNN module is trained to extract the features of CTA images, and then the branch classifier and direction predictor are designed to predict the most possible direction and lumen radius at the given centerline point. Besides, a new loss function is developed for associating the direction vector with the lumen radius. The whole process starts from a point manually placed at the coronary artery ostia, and terminates until tracking the vessel endpoint. The network was trained using a training set consisting of 12 CTA images and the evaluation was performed using a testing set consisting of 6 CTA images. The extracted centerlines had an average overlap (OV) of 89.19%, overlap until first error (OF) of 82.30%, and overlap with clinically relevant vessel (OT) of 91.42% with manually annotated reference. Our proposed method can efficiently deal with multi-branch problems and accurately detect distal coronary arteries, thereby providing potential help in assisting CAD diagnosis.

Quantifying myocardial perfusion during MR-guided interventions without exogenous contrast agents: intra-arterial spin labeling

PurposeTo test intra-arterial spin labeling (iASL) using active guiding catheters for myocardial perfusion measurements during magnetic resonance (MR)-guided interventions in a pig study. MethodsIn this work, a single-loop radiofrequency (RF) coil at the tip of a 6F active coronary catheter was used as a transmit coil for local spin labeling. The transmit magnetic RF field (B1) of the coil and the labeling efficiency were determined, and iASL was tested in two pigs after the catheter was engaged in the aortic root, the ostium of the left coronary artery (LCA) under MR-guidance. The iASL effect was assessed by the signal difference between spin-labeling On and control (spin-labeling OFF) images, and in a cross-correlation between ON/Off states of spin-labeling a binary labeling paradigm. In addition, quantitative myocardial perfusion was calculated from the iASL experiments. ResultsThe maximum B1 in the vicinity of the catheter coil was 2.1 µT. A strong local labeling effect with a labeling efficiency of 0.45 was achieved with iASL both in vitro and in vivo. In both pigs, the proximal myocardial segments supplied by the LCA showed significant labelling effect up to distances of 60 mm from the aortic root with a relative signal difference of (3.14 ± 2.89)% in the first and (3.50 ± 1.25)% in the second animal. The mean correlation coefficients were R = 0.63 ± 0.22 and 0.42 ± 0.16, respectively. The corresponding computed myocardial perfusion values in this region of the myocardium were similar to those obtained with contrast perfusion methods ((1.2 ± 1.1) mL/min/g and (0.8 ± 0.6) mL/min/g). ConclusionThe proposed iASL method demonstrates the feasibility of selective myocardial perfusion measurements during MR-guided coronary interventions, which with further technical improvements may provide an alternative to exogenous contrast-based perfusion. Due to the invasive nature of the iASL method, it can potentially be used in concert with MRI-guided coronary angioplasty.

Aortic valve leaflet disruption techniques in transcatheter aortic valve replacement.

With continued technological advancement and technical improvement of transcatheter aortic valve replacement (TAVR), it has become a desirable treatment option for aortic valve stenosis. Its minimally invasive approach compared to surgical aortic valve replacement offers the treatment to a broader patient population, mainly non-surgical candidates. A feared complication of TAVR is the occlusion of coronary artery ostium by the native aortic valve leaflet due to its displacement by the expanded transcatheter valve. Bioprosthetic or native aortic scallop intentional laceration to prevent iatrogenic coronary artery obstruction (BASILICA) is a technique developed to mitigate this risk by creating a lengthwise laceration of the left and/or right aortic valve leaflets prior to TAVR. Patient outcomes following TAVR with BASILICA have been promising. Meticulous preoperative examination, patient selection, and hemodynamic management are imperative. With continued refinement, BASILICA may further expand the application of TAVR to patients at high risk for coronary occlusion associated with the procedure.

Congenital Absence of Left Coronary Artery Ostium in a Patient Presenting With Anterior ST-Elevation Myocardial Infarction

A 73-year-old man developed chest pain 12 hours before arriving at our hospital. An electrocardiogram revealed ST-segment elevation in leads V2–V6 (Figure 1A); therefore, an emergent coronary angiography was performed. Several attempts were made to engage the left coronary artery (LCA), but they were unsuccessful. Left coronary cusp angiography and subsequent right coronary angiography demonstrated a single right coronary artery (RCA) with blood flow to the left circumflex coronary artery (LCX) and the congenital absence of the LCA ostium at the left, right, and posterior Valsalva sinuses (Figure 1B, Video 1).

1068 THE IMPACT OF COMMISSURAL ALIGNMENT ON CORONARY ARTERY ACCESS: A META ANALYSIS

Abstract Background The use of TAVR has been spreading out globally due to its favorable safety profile and the excellent efficacy data from randomized controlled trials. With the growing number of treated patients, the attention is rising around specific issues, such as the treatment of intercurrent coronary artery disease. Commissural alignment of transcatheter heart valves (THV) has the potential to reduce the impact of the prosthesis on accessibility of coronary ostia, as misalignment of the neo-commissures could be responsible for partial overlap with coronary artery ostia. However, no definitive evidence is available, despite multiple trials have addressed this issue. Methods The aim of this meta-analysis was to investigate the impact of the commissural alignment on coronary filling. We examined the techniques of commissural alignment and their impact on coronary access and coronary overlap. Eligible studies were searched for on Pubmed and SCOPUS and selected using the PRISMA guidelines. The primary endpoint is a composite of severe coronary overlap and failure of transcatheter coronary access. Odds Ratio were used as the metric for comparison between the groups. A random effects meta-analysis was selected as the calculation model. Results Six studies with a total of 1213 patients were included in this analysis. Of these patients, 757 patients underwent TAVR with commissural alignment and 456 underwent TAVR without commissural alignment. The composite endpoint of coronary overlap and failure of coronary access occurred in 118 patients undergoing TAVR with commissural alignment and in 124 patients without commissural alignment (OR=0.20, 95% CI 0.08-0.48; p= 0.0003). Conclusions Commissural alignment was associated with significantly lower rates of commissure-to-coronary-ostia overlap and failure of coronary access. Therefore, a modified insertion technique could reduce coronary overlap and coronary occlusion, particularly in supra-annular valves. Commissural alignment performed during TAVR could therefore have an important role in coronary re-access and re-intervention especially in younger patients.

A Case of Native Aortic Valve Thrombus Complicating Intermittent Occlusion of a Left Main Coronary Artery.

Intermittent left main coronary artery ostium obstruction (LMOO) caused by native aortic valve thrombus (NAVT) is an extremely rare condition. It may therefore be challenging to identify the cause using only coronary angiography, even though the clinical presentation and electrocardiography (ECG) strongly suggest myocardial infarction. We herein report a 53-year-old man with NAVT complicating intermittent occlusion of left main disease in preexisting coronary artery stenosis.

Coronary Artery Air Embolism in the Non-operating room Anesthesia Setting.

Coronary artery air embolism is a rare complication in the non–operating room anesthesia environment. In this setting, coronary artery air embolism is generally caused by communication between the atmosphere and the pulmonary venous system or by the creation of a bronchial-venous or alveolar-venous fistula during lung biopsy.1 Typical presentation is a result of the ensuing myocardial ischemia, and includes chest pain, arrhythmia, ST segment changes, bradycardia, hypotension, and cardiovascular collapse.2Figure 1 represents the intraprocedural computed tomography imaging of a 74-year-old woman who underwent percutaneous lung biopsy. Clearly visible is the air-fluid level in the ascending aorta, just distal to the right coronary artery ostia. Figure 2 shows air in the proximal right coronary artery. This patient’s procedural course was complicated by profound bradycardia, arrhythmia, and cardiogenic shock secondary to acute myocardial ischemia.Risk of coronary artery air embolism is underappreciated outside the cardiac operating room; thus, the anesthesiologist must maintain a high degree of suspicion and closely monitor the electrocardiogram for change. Risk factors include coughing, positive pressure ventilation, biopsy of cavitary lesions, and use of needle-within-needle biopsy systems.3 In supine patients, the right ventricle is particularly vulnerable to coronary artery air embolism secondary to the anterior takeoff of the right coronary. Treatment involves immediate Trendelenburg positioning to prevent cerebral air embolism, an inspiratory oxygen fraction of 1.0, central access, and catecholamine support of cardiac function and coronary perfusion pressure. Transcutaneous or transvenous pacing, as well as coronary angiography, aspiration, and localized vasodilator injection have also been trialed successfully in the catheterization laboratory.3 Finally, extracorporeal membrane oxygenation or cardiac bypass may be indicated if other measures fail.Support was provided solely from institutional and/or departmental sources.The authors declare no competing interests.