Left Atrial Hypertension Research Articles

Prevalence of Acute Lung Injury Among Medical Patients in the Emergency Department

Acute lung injury (ALI) affects an estimated 190,000 persons per year in U.S. intensive care units (ICUs), but little is known about its prevalence in the emergency department (ED). The objective was to describe the prevalence of ALI among mechanically ventilated adult nontrauma patients in the ED. The hypothesis was that the prevalence of ALI in adult ED patients would be low. This was a retrospective cohort study of admitted nontrauma patients presenting to an academic ED. Two trained investigators abstracted data from patient records using a standardized form. The use of mechanical ventilation in the ED was identified in two phases. First, all ED patients were screened for the current procedural terminology (CPT) code for endotracheal intubation (CPT 31500) from January 1, 2003, to December 31, 2006. Second, each patient record was reviewed to verify the use of mechanical ventilation. ALI was defined in accordance with a modified version of the American-European Consensus Conference criteria as: 1) hypoxemia defined as PaO(2) /FiO(2) ratio ≤300 mm Hg on all arterial blood gases (ABGs) in the ED and the first 24 hours of admission, 2) the presence of bilateral infiltrates on chest radiograph, and 3) the absence of left atrial hypertension. Data are presented in absolute numbers and percentages. Interobserver agreement was evaluated using the kappa statistic. Of the 552 patients who received mechanical ventilation in the ED and were subsequently admitted, a total of 134 (24.3%, 95% confidence interval [CI] = 20.8% to 28.0%) met hypoxemia criteria. Of these, 34 had evidence of left atrial hypertension, 52 did not have chest radiograph findings consistent with ALI, and two did not have a chest radiograph performed; the remaining 46 met ALI criteria. An additional two patients who died in the ED had clinical evidence of ALI. Thus, 48 of 552, or 8.7% (95% CI = 6.6% to 11.3%), met criteria for ALI. The kappa value for determination of ALI was 0.84 (95% CI = 0.54 to 1.0). The prevalence of ALI was nearly 9% in adult nontrauma patients receiving mechanical ventilation in the ED. Further study is required to determine which types of patients present to the ED with ALI, the extent to which lung protective ventilation is used, and the need for ED ventilator management algorithms.

World Health Organization Pulmonary Hypertension Group 2: Pulmonary hypertension due to left heart disease in the adult—a summary statement from the Pulmonary Hypertension Council of the International Society for Heart and Lung Transplantation

Pulmonary hypertension associated with left heart disease is the most common form of pulmonary hypertension encountered in clinical practice today. Although frequently a target of therapy, its pathophysiology remains poorly understood and its treatment remains undefined. Pulmonary hypertension in the context of left heart disease is a marker of worse prognosis and disease severity, but whether its primary treatment is beneficial or harmful is unknown. An important step to the future study of this important clinical problem will be to standardize definitions across disciplines to facilitate an evidence base that is interpretable and applicable to clinical practice. In this current statement, we provide an extensive review and interpretation of the current available literature to guide current practice and future investigation. At the request of the Pulmonary Hypertension (PH) Council of the International Society for Heart and Lung Transplantation (ISHLT), a writing group was assembled and tasked to put forth this document as described above. The review process was facilitated through the peer review process of the Journal of Heart and Lung Transplantation and ultimately endorsed by the leadership of the ISHLT PH Council.

Mock Circulation Simulation of Extracorporeal Membrane Oxygenation Support for Systemic Ventricular Failure in an Infant

Extracorporeal membrane oxygenation (ECMO) is often used to provide cardiopulmonary support for infants experiencing severe levels of cardiac or respiratory failure. In patients with two ventricles and no intra-atrial communication, ECMO is often complicated by limited venous return to the circuit and marked left atrial hypertension. This condition may be treated by performing an atrial septostomy to create an intentional atrial septal defect (ASD). A pediatric mock circulation with a conduit connecting the left and right atrium was used to examine the size of ASD that would relieve left atrial hypertension and restore acceptable hemodynamics in a 4 to 5 kg infant. After creation of left ventricular failure and subsequent institution of ECMO, the ASD was opened in a graded fashion while the resulting hemodynamic changes were recorded. An ASD equivalent to a 6.3 mm diameter hole decreased the left atrial pressure 30 mmHg to an acceptable level with a net left-to-right shunt of 393 ml/min. Further opening of the ASD resulted in additional hemodynamic improvement, but was eventually limited in further effect. This study demonstrates that a mock circulation can be used to investigate the size of an ASD necessary to effect sufficient clinical improvement in a two-ventricle infant on ECMO.

Prenatal diagnosis of atrial restriction in hypoplastic left heart syndrome is associated with decreased 2‐year survival

To compare the course of hypoplastic left heart syndrome (HLHS) patients diagnosed prenatally with any degree of atrial restriction with those without evidence of atrial restriction. Retrospective, cohort. Prenatally diagnosed HLHS patients from August 1999 to January 2009 were categorized as nonrestrictive versus restrictive, defined by left atrial hypertension on pulmonary venous Doppler and/or an intact interatrial septum. Of 73 total fetal patients identified, 49 were live-born. Survival at 2 years was 29/35 [83% confidence interval (CI): 59.5%-88.9%] for the nonrestrictive group and 6/14 (43% CI: 17.7%-6.0%) for the restrictive group (p<0.0001). Of those who underwent stage 1 palliation (35 with nonrestrictive and 10 with restrictive atrial septa), both groups had a similar incidence of preoperative acidosis and need for ventilation and inotropic support. Postoperatively, there was no difference between groups in ventilator days, length of stay, or survival to discharge. There was decreased survival at 2 years in the restrictive group, 60% (CI: 26.2%-87.8%) versus 83% (CI: 66.4%-93.4%) in the nonrestrictive group. Furthermore, a disproportionate number of interstage deaths was evident in the restrictive group. Prenatal presence of any degree of atrial septal restriction in the setting of HLHS confers a significant survival disadvantage, with increases in both early and late mortality.

The Use of Reconstructive Surgery to Improve Quality of Life and Survival in Prenatal Hypoplastic Left Heart Syndrome

Outcomes for hypoplastic left heart syndrome have improved substantially in the era of prenatal diagnosis. Current stage 1 survival rates are in excess of 90% in the absence of risk factors. However, fetuses with an intact atrial septum continue to have poor postnatal survival. Accurate diagnosis of these fetuses with an intact atrial septum relies upon careful assessment of the patent foramen ovale, pulmonary venous Doppler flow patterns and branch pulmonary artery Doppler flow patterns. Prenatal and perinatal interventions, such as the placement of an atrial stent in utero or delivery at a center where a stent may be placed immediately after birth to relieve left atrial hypertension, may improve survival in this particularly high-risk group.

Atrial Fibrillation Catheter Ablation Versus Surgical Ablation Treatment (FAST)

Background— Catheter ablation (CA) and minimally invasive surgical ablation (SA) have become accepted therapy for antiarrhythmic drug–refractory atrial fibrillation. This study describes the first randomized clinical trial comparing their efficacy and safety during a 12-month follow-up. Methods and Results— One hundred twenty-four patients with antiarrhythmic drug–refractory atrial fibrillation with left atrial dilatation and hypertension (42 patients, 33%) or failed prior CA (82 patients, 67%) were randomized to CA (63 patients) or SA (61 patients). CA consisted of linear antral pulmonary vein isolation and optional additional lines. SA consisted of bipolar radiofrequency isolation of the bilateral pulmonary vein, ganglionated plexi ablation, and left atrial appendage excision with optional additional lines. Follow-up at 6 and 12 months was performed by ECG and 7-day Holter recording. The primary end point, freedom from left atrial arrhythmia &gt;30 seconds without antiarrhythmic drugs after 12 months, was 36.5% for CA and 65.6% for SA ( P =0.0022). There was no difference in effect for subgroups, which was consistent at both sites. The primary safety end point of significant adverse events during the 12-month follow-up was significantly higher for SA than for CA (n=21 [34.4%] versus n=10 [15.9%]; P =0.027), driven mainly by procedural complications such as pneumothorax, major bleeding, and the need for pacemaker. In the CA group, 1 patient died at 1 month of subarachnoid hemorrhage. Conclusion— In atrial fibrillation patients with dilated left atrium and hypertension or failed prior atrial fibrillation CA, SA is superior to CA in achieving freedom from left atrial arrhythmias after 12 months of follow-up, although the procedural adverse event rate is significantly higher for SA than for CA. Clinical Trial Registration— URL: http://clinicaltrials.gov . Unique identifier: NCT00662701.

First do no harm: surrogate endpoints and the lesson of β-agonists in acute lung injury

Expanded abstractCitationMatthay MA, Brower RG, Carson S, Douglas IS, Eisner M, Hite D, Holets S, Kallet RH, Liu KD, MacIntyre N, Moss M, Schoenfeld D, Steingrub J, Thompson BT: Randomized, placebo-controlled clinical trial of an aerosolized β-agonist for treatment of acute lung injury. National Heart, Lung, and Blood Institute Acute Respiratory Distress Syndrome (ARDS) Clinical Trials Network. Am J Respir Crit Care Med 2011, 184:561-568.Backgroundβ2-Adrenergic receptor agonists accelerate resolution of pulmonary edema in experimental and clinical studies of acute lung injury (ALI).MethodsObjective: To determine whether an aerosolized β2-agonist would improve clinical outcomes in patients with ALI.Design: Multi-center, phase III randomized, placebo-controlled clinical trial.Setting: 33 hospitals participating National Heart, Lung, and Blood Institute Acute Respiratory Distress Syndrome (ARDS) Clinical Trials Network.Subjects: Patients who were intubated and receiving mechanical ventilation, had bilateral infiltrates consistent with edema on frontal chest radiograph, had a ratio of PaO2 to FIO2 (fraction of inspired oxygen) of 300 or less, and not had clinical evidence of left atrial hypertension. A maximum enrolment of 1,000 patients was planned.Intervention: Patients were randomized to receive aerosolized albuterol (5 mg) or saline placebo every 4 hours for up to 10 days.Outcomes: The primary outcome variable was ventilator-free days (VFD). Secondary outcome measures included mortality before hospital discharge on day 60 and day 90, the number of intensive care unit (ICU)-free days and the number of organ failure-free days.ResultsThere were 282 patients enrolled before the trial was stopped for futility after the second interim analysis. The VFDs difference with albuterol treatment was unfavourable by -2.2 days, well past the futility boundary of -0.4 VFDs. VFDs were not significantly different between the albuterol and placebo groups (means of 14.4 and 16.6 days, respectively; 95% confidence interval for the difference, -4.7 to 0.3 days; P = 0.087). Rates of death before hospital discharge and the number of organ failure-free days were also not significantly different between the two groups. The number of ICU-free days was lower in the albuterol group in comparison with the placebo group (means of 13.5 and 16.2 days respectively; 95% confidence intervals for the mean difference, -4.9 to -0.4 days; P = 0.023). Overall, heart rates were significantly higher in the albuterol group by approximately 5 beats/minute in the first 2 days after randomization (P < 0.05), but rates of new onset atrial fibrillation (10% in both groups) and other cardiac dysrhythmias were not significantly different.ConclusionsThese results suggest that aerosolized albuterol does not improve clinical outcomes in ALI patients. Routine use of β2 agonist therapy in mechanically ventilated ALI patients cannot be recommended.

The role of neuromuscular blocking drugs in early severe acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is defined as severe hypoxemic respiratory failure resulting from diffuse lung injury and secondary to direct and indirect insults. Despite advances, mortality remains as high as 40-60%. Neuromuscular blocking agents (NMBAs) are used to facilitate mechanical ventilation in patients with ARDS and have been shown to improve arterial partial pressure of oxygen. However, the association between NMBAs and mortality is unclear. Furthermore, morbidity concerns exist, particularly regarding a putative role in intensive care unit (ICU)-acquired weakness. The purpose of this study was to compare survival in adult patients with early ARDS who were randomized to receive either a 48-hr infusion of the NMBA, cisatracurium, or a placebo. This study was a multicentre double-blinded randomized controlled trial involving 20 ICUs in France from March 2006 to March 2008. Eligible patients were > 18 yr with an intubated trachea and ventilated lungs for acute hypoxemic respiratory failure. Their PaO(2)/F(i)O(2) ratio was < 150 at a tidal volume of 6-8 mL·kg(-1) ideal body weight and a positive end-expiratory pressure (PEEP) ≥ 5 cm H(2)O for < 48 hr. Additional inclusion criteria were radiographic evidence of bilateral pulmonary infiltrates and the absence of left atrial hypertension. Exclusion criteria included patients already receiving NMBA at enrolment; those who had increased intracranial pressure, severe chronic respiratory disease, or severe chronic liver disease; those who had received a bone marrow transplant or had chemotherapy-induced neutropenia; those who had a pneumothorax; and those who were expected to require mechanical ventilation for < 48 hr or were enrolled in another trial within 30 days. Three hundred twenty-six patients were screened, and 340 of these underwent randomization in blocks of four and received either a 48-hr infusion of cisatracurium (15 mg bolus followed by 37.5 mg·hr(-1)) or a volume equivalent placebo. One hundred and seventy-eight patients received a cisatracurium infusion, and one patient withdrew leaving 177 patients included in the analysis. One hundred and sixty-two patients received the placebo infusion. Prior to either infusion, patients were sedated to a Ramsay sedation score of 6. Patients' lungs were ventilated by a volume assist-controlled mode according to the ARDS Clinical Network Mechanical Ventilation Protocol (http://www.ardsnet.org/) with the goal SpO(2) of 88-95% (or PaO(2) 55-80 mmHg) and goal plateau pressure ≤ 35 cm H(2)O. Open-label boluses of cisatracurium 20 mg (maximum of two per 24-hr period) were allowed if plateau pressures remained > 32 cm H(2)O despite increased sedation and despite decreased PEEP and decreased tidal volumes. Monitoring of paralysis via peripheral nerve stimulation was not permitted. The primary outcome was death before hospital discharge and within 90 days of study enrolment. It was determined a priori that this would be adjusted for imbalance in key risk factors at baseline, as derived from Cox regression. Secondary outcomes included 28-day mortality, number of ventilator-free days, number of days outside of ICU, number of days without organ system failure, rate of barotrauma, and rate of ICU-acquired paresis (as defined by a Medical Research Council [MRC] score < 48) on day 28 and at ICU discharge. With regard to the primary outcome, crude 90-day mortality was 31.6% in the cisatracurium group vs 40.7% in the placebo group. This outcome did not reach statistical significance (P = 0.08). However, post hoc analysis found a reduction in 90-day mortality in the cisatracurium group compared with placebo (95% confidence interval 0.48 to 0.98; P = 0.04). Results suggest that the reduction in 90-day mortality in the cisatracurium group was confined to those patients with a PaO(2)/F(i)O(2) ratio < 120. Additionally, 28-day mortality was significantly lower in the cisatracurium group (absolute difference -9.6%; P = 0.05). The cisatracurium group also had significantly more ventilator-free days, more days outside of the ICU, and more days free of organ-failure. Similarly, pneumothorax developed more often and earlier in the placebo group than in the cisatracurium group. The rate of ICU-acquired weakness at day 28 or at ICU discharge did not differ significantly between the two groups. Treatment in early severe ARDS with the NMBA, cisatracurium, for 48 hr was associated with lower adjusted 90-day mortality. It was also associated with decreased morbidity, which included increased ventilator-free days, increased ICU-free days, and increased organ failure-free days. These benefits occurred without increasing the incidence of ICU-acquired weakness.

Abstract P270: Systolic Pulmonary Artery Pressure Predicts Hospital Readmission in Patients with Congestive Heart Failure

Background: Left atrial hypertension results in pulmonary hypertension which is a frequent finding in the setting of left ventricular failure. We hypothesized that noninvasive measurement of systolic pulmonary artery pressure (SPAP) by echocardiography could be used to estimate the risk of hospital readmission in patients with congestive heart failure (CHF). Methods: We conducted a retrospective cohort study on patients discharged from a major urban hospital between June 2009 and October 2009 with a primary diagnosis of CHF. Noninvasive assessment of SPAP by 2D echocardiography performed within 6 months preceding hospital discharge was among the inclusion criteria. A SPAP of 40 mmHg or greater in addition to other factors potentially predictive of re-hospitalization were included in a univariable cox-regression analysis for predicting all-cause readmission. Variables with p-values less than 0.25 were allowed to participate in a stepwise cox-regression model which identified all statistically significant predictors within a mutlivariable setting. Results: 145 patients participated in the stepwise cox-regression analysis. The mean SPAP (mmHg) was 47 with a median of 46. The following statistically significant predictors were identified: hemoglobin nadir &lt; 10 g/dl (HR 1.63; 95% CI 1.07-2.48; P = 0.02), requirement of skilled nursing care after discharge (HR 1.73; 95% CI 1.14-2.63; P = 0.011), diagnosis of COPD (HR 1.62; 95% CI 1.04-2.51; P = 0.03), diagnosis of ESRD (HR 2.05; 95% CI 1.18-3.55; P = 0.01), use of cardiac resynchronization therapy (HR 4.71; 95% CI 1.95-11.35; P &lt; 0.001) and SPAP of 40 or above (HR 2.03; 95% CI 1.30-3.18; P = 0.002). Conclusions: Previous limited studies have suggested that pulmonary hypertension is a prognostic marker in patients with cardiomyopathy. Our data suggests that noninvasive measurement of SPAP by echocardiography can help to predict the risk of hospital readmission in patients hospitalized for CHF. A systolic PAP of 40 mmHg or above appears to be a stronger predictor of re-hospitalization when compared to traditional risk factors including COPD, ESRD and anemia.

Postnatal Left Ventricular Diastolic Function After Fetal Aortic Valvuloplasty

Fetal aortic balloon valvuloplasty (FAV) has shown promise in altering in utero progression of aortic stenosis to hypoplastic left heart syndrome. In patients who achieve a biventricular circulation after FAV, left ventricular (LV) compliance may be impaired. Echocardiographic indexes of diastolic function were compared between patients with biventricular circulation after FAV, congenital aortic stenosis (AS), and age-matched controls. In the neonatal period, patients with FAV had similar LV, aortic, and mitral valve dimensions but more evidence of endocardial fibroelastosis than patients with AS. Patients with FAV underwent more postnatal cardiac interventions than patients with AS (p = 0.007). Mitral annular early diastolic tissue velocity (E') was lower in patients with FAV and those with AS and controls in the neonatal period and over follow-up (p <0.001). Septal E' was similar among all 3 groups in the neonatal period. In follow-up patients, with FAV had lower septal E' than patients with AS or controls (p <0.001). Early mitral inflow velocity/E' was higher in patients with FAV as neonates and at follow-up (p <0.001). Mitral inflow pulse-wave Doppler-derived indexes of diastolic function were similar between groups. In conclusion, echocardiographic evidence of LV diastolic dysfunction is common in patients with biventricular circulation after FAV and persists in short-term follow-up. LV diastolic dysfunction in this unique population may have important implications on long-term risk of left atrial and subsequent pulmonary hypertension.

Right ventricular dilatation: an often neglected component in the electrocardiographic assessment of patients with heart failure

When assessing patients with heart failure (HF) using the electrocardiogram (ECG), the primary focus is on the left ventricle and left atrium. Clinicians look for left ventricular hypertrophy, evidence of previous or current myocardial infarction, ST/T changes suggestive of left ventricular strain, or myocardial injury or ischaemia, perturbations of the QRS complex amplitude, depending on the patients' oedematous state,1 and left atrial hypertrophy, dilatation, or hypertension, since the last three cannot be differentiated by the ECG. However, major changes in the size and function of the right ventricle and right atrium take place in patients with HF, depending on the degree of compensation consequent to the natural course and the impact of co-morbidities, and therapeutic modalities. Such changes are reflected in the ECG as additional to the changes signifying left ventricular/atrial involvement, or cause partial or complete cancellation of the features attributed to the left ventricular/atrial pathology. Although right ventricular …

Survival after extreme left atrial hypertension and pulmonary hemorrhage in an infant supported with extracorporeal membrane oxygenation for refractory atrial flutter

We report here the survival of an infant who developed extreme left atrial hypertension and severe pulmonary hemorrhage while supported with extracorporeal membrane oxygenation for refractory atrial flutter. The patient recovered after decompression of the left heart and catheter ablation of the atrioventricular node. Lucile Packard Children's Hospital (Stanford, CA). Chart review. Recovery of lung function is possible despite systemic-level left atrial pressure resulting in pulmonary hemorrhage and complete solidification of lung parenchyma on gross inspection. Resolution of pulmonary hemorrhage despite anticoagulation while on extracorporeal membrane oxygenation can occur after relief of left atrial hypertension.

Hypoplastic Left Heart Syndrome With Intact Atrial Septum: Sequelae of Left Atrial Hypertension In Utero

![Figure][1] [![Graphic][3] ][3][![Graphic][4] ][4][![Graphic][5] ][5] A fetus diagnosed with hypoplastic left heart syndrome and intact atrial septum with severe left atrial (LA) and pulmonary venous hypertension ( A and B , [Online Video 1][5]) was delivered at 38 weeks

Pumpless extracorporeal lung assist in a pregnant woman with severe ARDS

Acute respiratory distress syndrome is characterized by acute-onset, refractory hypoxemia, bilateral infiltrates on chest radiographs and PAOP <18 mmHg or absence of clinical signs of left atrial hypertension. The protective ventilatory strategy limiting plateau pressure to lower than 28 cmH2O, driving pressure below 15 cmH2O and tidal volume between 4 and 6 ml/kg using a PEEP level to sustain the open lung approach usually results in hypercapnia. However, it is the mainstream supportive therapy that can modulate survival in this syndrome.

Therapeutic strategy for acute respiratory distress syndrome: recent understanding of the pathophysiology of the disease

Acute respiratory distress syndrome (ARDS) features acute onset, severe hypoxemia, bilateral infiltrates documented by chest radiograph, and the absence of left atrial hypertension. Factors that lead to this syndrome vary from direct lung damage, including respiratory infection, aspiration, inhalation of chemical or poisonous gas, pulmonary contusion, and pulmonary ischemia–reperfusion, to indirect causes including sepsis, acute pancreatitis, severe trauma, cardiopulmonary bypass, and transfusion. Epidemiology of ARDS

Autonomic activation links CNS oxygen toxicity to acute cardiogenic pulmonary injury

Breathing hyperbaric oxygen (HBO₂), particularly at pressures above 3 atmospheres absolute, can cause acute pulmonary injury that is more severe if signs of central nervous system toxicity occur. This is consistent with the activation of an autonomic link between the brain and the lung, leading to acute pulmonary oxygen toxicity. This pulmonary damage is characterized by leakage of fluid, protein, and red blood cells into the alveoli, compatible with hydrostatic injury due to pulmonary hypertension, left atrial hypertension, or both. Until now, however, central hemodynamic parameters and autonomic activity have not been studied concurrently in HBO₂, so any hypothetical connections between the two have remained untested. Therefore, we performed experiments using rats in which cerebral blood flow, electroencephalographic activity, cardiopulmonary hemodynamics, and autonomic traffic were measured in HBO₂ at 5 and 6 atmospheres absolute. In some animals, autonomic pathways were disrupted pharmacologically or surgically. Our findings indicate that pulmonary damage in HBO₂ is caused by an abrupt and significant increase in pulmonary vascular pressure, sufficient to produce barotrauma in capillaries. Specifically, extreme HBO₂ exposures produce massive sympathetic outflow from the central nervous system that depresses left ventricular function, resulting in acute left atrial and pulmonary hypertension. We attribute these effects on the heart and on the pulmonary vasculature to HBO₂-mediated central sympathetic excitation and catecholamine release that disturbs the normal equilibrium between excitatory and inhibitory activity in the autonomic nervous system.

Management of Acute Lung Injury/ARDS

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are disorders of pulmonary inflammation characterized by hypoxemia and respiratory failure. Children have varying incidence of ALI/ARDS from 2.2 to 16 per 100,000 pediatric population associated with high morbidity, mortality, and financial burden. The diagnostic criteria include: acute onset, severe arterial hypoxemia resistant to oxygen therapy alone (PaO₂/FIO₂ ratio ≤ 200 for ARDS and ≤ 300 for ALI), diffuse pulmonary inflammation (bilateral infiltrates on chest radiograph) and No evidence of left atrial hypertension. Management includes ventilatory therapy including lower tidal volume, relatively high PEEP and supportive care. Guidelines for diagnosis, ventilator management, rescue therapies and supportive care are being discussed in the protocol.

Transthoracic echocardiographic assistance for interatrial stenting in low birth‐Weight neonates with hypoplastic left heart syndrome and intact atrial septum

Infants with hypoplastic left heart syndrome and intact or highly restrictive atrial septum require emergent therapy to relieve pulmonary congestion. Transcatheter stenting has become, in most large centers, the mainstay of therapy for relief of left atrial hypertension. Normally, this procedure is performed with the assistance of transesophageal echocardiographic guidance. However, the transesophageal approach is untenable in neonates of low birth weight, as the transducers can be traumatic and can cause ventilatory difficulty. We present two cases in which transthoracic echocardiographic guidance was used to guide atrial perforation and stenting in low birth-weight neonates with hypoplastic left heart syndrome with intact or highly restrictive atrial septum. Both procedures were straightforward and there were no complications. Real-time biplane imaging greatly assisted in the intervention in one case. The advantages of this approach are discussed.

Imaging of acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) describes a relatively common and frequently lethal syndrome at the severe end of the spectrum of acute lung injury. Onset of symptoms is usually within 72 h of the inciting event and complicates a wide variety of clinical disorders, ranging from infection to trauma. It may be defined as resistant hypoxaemia in the clinical setting of one of the group of recognised causes, in association with bilateral pulmonary infiltrates and in the absence of left atrial hypertension. Accurate diagnosis and differentiation from other treatable conditions is crucial. This publication addresses the clinical and radiological features of ARDS, a review of the imaging technology with illustrations and differential diagnosis. This paper will give insight into the strengths and weaknesses of imaging modalities used in the management of patients with ARDS. Imaging plays a vital role in the assessment of acute respiratory syndromes. Computed tomography is much more sensitive compared with chest radiography, and relatively under-utilised. Other methods, such as bedside ultrasound and impedance tomography, may have roles to play in the future.

Left Atrial Hypertension as a Result of Occlusion of a Patent Foreman Ovale

A 70-year-old woman with a history of hypertension, pulmonary hypertension, and transient ischemic attack was referred for transcatheter closure of a patent foramen ovale (PFO). The patient complained of dyspnea on exertion but showed no other signs of heart failure. A previous transthoracic echocardiogram had documented normal left ventricular size and function, continuous left-to-right shunting across the PFO, right ventricular enlargement, severe pulmonary hypertension, and a Qp:Qs ratio of 1.4:1 calculated by Doppler echocardiography. The patient was brought into the procedure room to undergo catheter-based closure of the PFO. Transesophageal echocardiography was performed throughout the procedure and confirmed the presence of a characteristic PFO with left-to-right shunting across the space between the septum primum and secundum (Figure 1). Figure 1. Color Doppler image of left-to-right shunt across a characteristic PFO, demonstrating flow between the septum primum and secundum. LA indicates left atrium; RA, right atrium. Venous access was obtained through …