Measured Oxygen Consumption During Pediatric Cardiac Catheterization is More Accurate than Assumed Oxygen Consumption.

When calculating cardiac index (C.I.) by the Fick method, oxygen consumption (VO2) is often unknown, so assumed values are typically used. This practice introduces a known source of inaccuracy into the calculation. Using a measured VO2 (mVO2) from the CARESCAPE E-sCAiOVX module provides an alternative that may improve accuracy of C.I. calculations. Our aim is to validate this measurement in a general pediatric catheterization population and compare its accuracy with assumed VO2 (aVO2). mVO2 was recorded for all patients undergoing cardiac catheterization with general anesthesia and controlled ventilation during the study period. mVO2 was compared to the reference VO2 (refVO2) determined by the reverse Fick method using cardiac MRI (cMRI) or thermodilution (TD) as a reference standard for measurement of C.I. when available. 193 VO2 measurements were obtained, including 71 with a corresponding cMRI or TD measure of cardiac index for validation. mVO2 demonstrated satisfactory concordance and correlation with the TD- or cMRI-derived refVO2 (ρc = 0.73, r2 = 0.63) with a mean bias of - 3.2% (SD ± 17.3%). Assumed VO2 demonstrated much weaker concordance and correlation with refVO2 (ρc = 0.28, r2 = 0.31) with a mean bias of + 27.5% (SD ± 30.0%). Subgroup analysis of patients < 36 months of age demonstrated that error in mVO2 was not significantly different from that observed in older patients. Many previously reported prediction models for assuming VO2 performed poorly in this younger age range. Measured oxygen consumption using the E-sCAiOVX module is significantly more accurate than assumed VO2 when compared to TD- or cMRI-derived VO2 in a pediatric catheterization lab.

X-ray fused with MRI guidance of pre-selected transcatheter congenital heart disease interventions.

OBJECTIVES: To determine whether X-ray fused with MRI (XFM) is beneficial for select transcatheter congenital heart disease interventions. BACKGROUND: Complex transcatheter interventions often require three-dimensional (3D) soft tissue imaging guidance. Fusion imaging with live X-ray fluoroscopy can potentially improve and simplify procedures. METHODS: Patients referred for select congenital heart disease interventions were prospectively enrolled. Cardiac MRI data was overlaid on live fluoroscopy for procedural guidance. Likert scale operator assessments of value were recorded. Fluoroscopy time, radiation exposure, contrast dose, and procedure time were compared to matched cases from our institutional experience. RESULTS: Forty-six patients were enrolled. Pre-catheterization, same day cardiac MRI findings indicated intervention should be deferred in nine patients. XFM-guided cardiac catheterization was performed in 37 (median age 8.7 years [0.5-63 years]; median weight 28 kg [5.6-110 kg]) with the following prespecified indications: pulmonary artery (PA) stenosis (n = 13), aortic coarctation (n = 12), conduit stenosis/insufficiency (n = 9), and ventricular septal defect (n = 3). Diagnostic catheterization showed intervention was not indicated in 12 additional cases. XFM-guided intervention was performed in the remaining 25. Fluoroscopy time was shorter for XFM-guided intervention cases compared to matched controls. There was no significant difference in radiation dose area product, contrast volume, or procedure time. Operator Likert scores indicated XFM provided useful soft tissue guidance in all cases and was never misleading. CONCLUSIONS: XFM provides operators with meaningful three-dimensional soft tissue data and reduces fluoroscopy time in select congenital heart disease interventions.

Anesthetic considerations for magnetic resonance imaging-guided right-heart catheterization in pediatric patients: A single institution experience.

Cardiac catheterization is an integral part of medical management for pediatric patients with congenital heart disease. Owing to age and lack of cooperation in children who need this procedure, general anesthesia is typically required. These patients have increased anesthesia risk secondary to cardiac pathology. Furthermore, multiple catheterization procedures result in exposure to harmful ionizing radiation. Magnetic resonance imaging-guided right-heart catheterization offers decreased radiation exposure and diagnostic imaging benefits over traditional fluoroscopy but potentially increases anesthetic complexity and risk. We describe our early experience with anesthetic techniques and challenges for pediatric magnetic resonance imaging-guided right-heart catheterization.

Increasing propensity to pursue operative closure of atrial septal defects following changes in the instructions for use of the Amplatzer Septal Occluder device: An observational study using data from the Pediatric Health Information Systems database.

Concern for device erosion following transcatheter treatment of atrial septal defects (TC-ASD) led in 2012 to a United States Food and Drug Administration panel review and changes in the instructions for use of the Amplatzer Septal Occluder (ASO) device. No studies have assessed the effect of these changes on real-world practice. To this end a multicenter observational study was performed to evaluate trends in the treatment of ASD. METHODS: A retrospective observational study was performed using data from the Pediatric Health Information Systems database of all patients with isolated ASD undergoing either TC-ASD or operative ASD closure (O-ASD) from January 1, 2007, to September 30, 2015, hypothesizing that the propensity to pursue O-ASD increased beginning in 2013. RESULTS: A total of 6,392 cases from 39 centers underwent ASD closure (82% TC-ASD). Adjusting for patient factors, between 2007 and 2012, the probability of pursuing O-ASD decreased (odds ratio [OR] 0.95 per year, P = .03). This trend reversed beginning in 2013, with the probability of O-ASD increasing annually (OR 1.21, P = .006). There was significant between-hospital variation in the choice between TC-ASD and O-ASD (median OR 2.79, P < .0001). The age of patients undergoing ASD closure (regardless of method) decreased over the study period (P = .04). Cost of O-ASD increased over the study period, whereas cost of TC-ASD and length of stay for both O-ASD and TC-ASD was unchanged. CONCLUSIONS: Although TC-ASD remains the predominant method of ASD closure, the propensity to pursue O-ASD has increased significantly following changes in instructions for use for ASO. Further research is necessary to determine what effect this has on outcomes and resource utilization.

Radiation-free CMR diagnostic heart catheterization in children.

BACKGROUND: Children with heart disease may require repeated X-Ray cardiac catheterization procedures, are more radiosensitive, and more likely to survive to experience oncologic risks of medical radiation. Cardiovascular magnetic resonance (CMR) is radiation-free and offers information about structure, function, and perfusion but not hemodynamics. We intend to perform complete radiation-free diagnostic right heart catheterization entirely using CMR fluoroscopy guidance in an unselected cohort of pediatric patients; we report the feasibility and safety. METHODS: We performed 50 CMR fluoroscopy guided comprehensive transfemoral right heart catheterizations in 39 pediatric (12.7 ± 4.7 years) subjects referred for clinically indicated cardiac catheterization. CMR guided catheterizations were assessed by completion (success/failure), procedure time, and safety events (catheterization, anesthesia). Pre and post CMR body temperature was recorded. Concurrent invasive hemodynamic and diagnostic CMR data were collected. RESULTS: During a twenty-two month period (3/2015 - 12/2016), enrolled subjects had the following clinical indications: post-heart transplant 33%, shunt 28%, pulmonary hypertension 18%, cardiomyopathy 15%, valvular heart disease 3%, and other 3%. Radiation-free CMR guided right heart catheterization attempts were all successful using passive catheters. In two subjects with septal defects, right and left heart catheterization were performed. There were no complications. One subject had six such procedures. Most subjects (51%) had undergone multiple (5.5 ± 5) previous X-Ray cardiac catheterizations. Retained thoracic surgical or transcatheter implants (36%) did not preclude successful CMR fluoroscopy heart catheterization. During the procedure, two subjects were receiving vasopressor infusions at baseline because of poor cardiac function, and in ten procedures, multiple hemodynamic conditions were tested. CONCLUSIONS: Comprehensive CMR fluoroscopy guided right heart catheterization was feasible and safe in this small cohort of pediatric subjects. This includes subjects with previous metallic implants, those requiring continuous vasopressor medication infusions, and those requiring pharmacologic provocation. Children requiring multiple, serial X-Ray cardiac catheterizations may benefit most from radiation sparing. This is a step toward wholly CMR guided diagnostic (right and left heart) cardiac catheterization and future CMR guided cardiac intervention. TRIAL REGISTRATION: ClinicalTrials.gov NCT02739087 registered February 17, 2016.

Outcomes of Patients with Pulmonary Atresia and Major Aortopulmonary Collaterals Without Intervention in Infancy.

Treatment of pulmonary atresia with major aortopulmonary collaterals (PA MAPCAs) remains a challenge. Despite variations in surgical technique, contemporary strategies all include initial intervention in the first year of life. However, a subset of patients presents later in life, and contemporary outcomes of this group have not been reported previously. We performed a retrospective case series of consecutive cases of PA MAPCAs who were seen at our center between January 2001 and February 2016, who had not undergone surgery before the age of 1 year. We describe their presenting characteristics, operative and transcatheter interventions, and outcomes. A total of eight cases were identified from 76 children with PA MAPCAs treated over the study period. Median age at presentation was 5.9 years. Seventy-five percent had confluent pulmonary arteries with a median Nakata index of 113 mm(2)/m(2). Operative intervention was performed in 5/6 cases. Two are awaiting intervention. The combination of operative and transcatheter interventions allowed for ventricular septal defect closure in 60 % of cases, all of whom had subsystemic right ventricular pressures. Operative intervention is possible in some older cases with PA and MAPCAs. Though multiple operations and transcatheter therapies are necessary, some can achieve operative correction of serial circulation with tolerable physiology. Subjects with ventricular hypoplasia and those without confluent pulmonary arteries are more challenging.

Renal artery stenosis in children: therapeutic percutaneous balloon and stent angioplasty.

BACKGROUND: Renal artery stenosis (RAS) accounts for 10 % of cases of systemic hypertension in children. Initial management involves anti-hypertensive therapy. Percutaneous interventions are documented for the treatment of RAS in the adult population. In children, case reports suggest benefit. METHODS: This is a retrospective analysis of consecutive patients referred for catheterization for RAS between 2002 and 2010 at a single institution. Recorded variables included: age, weight, systemic blood pressure, minimal luminal diameter, interventional devices, antihypertensive medications, contrast volume, and complications. RESULTS: Twelve patients (median age 8.2, IQR 6-12.4 years); median weight 42.8 kg, IQR: 25-47.4 kg) were referred for renal artery catheterization and underwent percutaneous intervention. Overall, minimal luminal diameter (MLD) increased by 1.2 ± 0.9 mm for all patients (p < 0.05) and by 1.3 ± 0.9 mm for post-renal transplant patients (p < 0.05). Only stent angioplasty patients demonstrated significant improved blood pressure (p < 0.05). One patient had stent thrombosis requiring re-intervention with repeat balloon angioplasty. CONCLUSIONS: This retrospective analysis suggests that percutaneous intervention might play a role in the management of RAS, with an improvement in MLD in children with RAS. Transcatheter intervention is technically feasible with low morbidity. A prospective, longitudinal study is warranted to compare standard medical therapy with percutaneous interventions.

Magnetic Resonance Imaging-Guided Cardiac Catheterization Evacuation Drills.

BACKGROUND: The interventional cardiac magnetic resonance imaging suite combines a cardiac catheterization x-ray laboratory with a magnetic resonance imaging suite. At the study institution, interventional cardiac magnetic resonance imaging procedures (ie, magnetic resonance imaging-guided cardiac catheterizations) have been performed under institutional review board-approved research protocols since 2015. Because the workplace incorporates x-ray and magnetic resonance imaging in a highly technical environment, education about the importance of magnet safety is crucial to ensure the safety of patients and staff. OBJECTIVE: To promote magnetic resonance imaging safety and staff preparedness to respond in emergency situations in a specialized interventional cardiac magnetic resonance imaging environment. METHODS: Quarterly in situ evacuation drills with a live volunteer were implemented. A retrospective participant survey using a Likert scale was conducted. Evacuations were timed from the cardiac arrest code alert to safe evacuation or defibrillation if appropriate. RESULTS: Over 4 years, 14 drills were performed. Twenty-nine of 48 participants responded to the survey, a 60% response rate. Most participants agreed or strongly agreed that the drills were a positive experience (90%) and that the drills increased their confidence in their ability to perform in an evacuation scenario (100%). Room evacuation times improved from 71 to 41 seconds. No patient or staff safety events occurred in the interventional cardiac magnetic resonance imaging environment. CONCLUSION: Magnetic resonance imaging-guided cardiac catheterization evacuation drills promote preparedness, ensure patient and staff safety, and improve evacuation time in the interventional cardiac magnetic resonance imaging environment.

Detection of carbon monoxide during routine anesthetics in infants and children.

BACKGROUND: Carbon monoxide (CO) can be produced in the anesthesia circuit when inhaled anesthetics are degraded by dried carbon dioxide absorbent and exhaled CO can potentially be rebreathed during low-flow anesthesia. Exposure to low concentrations of CO (12.5 ppm) can cause neurotoxicity in the developing brain and may lead to neurodevelopmental impairment. In this study, we aimed to quantify the amount of CO present within a circle system breathing circuit during general endotracheal anesthesia in infants and children with fresh strong metal alkali carbon dioxide absorbent and define the variables associated with the levels detected. METHODS: Fifteen infants and children (aged 4 months to 8 years) undergoing mask induction followed by general endotracheal anesthesia were evaluated in this observational study. CO was measured in real time from the inspiratory limb of the anesthesia circuit every 5 minutes for 1 hour during general anesthesia. Carboxyhemoglobin (COHb) levels were measured at the 1-hour time point and compared with baseline. RESULTS: CO was detected in all patients older than 2 years (0-18 ppm, mean 3.7 +/- 4.8 ppm) and rarely detected in patients younger than 2 years (0-2 ppm, mean 0.2 +/- 0.6 ppm). Only the relationship between CO concentration and fresh gas flow to minute ventilation ratio (FGF:(.)VE) remained significant after adjustment in longitudinal regression analysis (P < 0.001). Although not powered to determine such a relationship, CO levels were weakly associated with the use of desflurane and female sex. There was no significant association between CO concentration and anesthetic concentration. Baseline COHb levels were higher in children younger than 2 years and decreased significantly at the 1-hour time point compared with baseline and children older than 2 years. However, COHb levels increased significantly from baseline in a predictable manner consistent with CO exposure in children older than 2 years. FGF:(.)VE correlated significantly with change in COHb using simple linear regression (r = 0.62; P < 0.02). CONCLUSIONS: CO was detected routinely during general anesthesia in infants and children when FGF:(.)VE was <1. Peak CO levels measured in the anesthesia breathing circuit were in the range thought to impair the developing brain. Further study is required to identify the source of CO detected (CO produced by degradation of volatile anesthetic versus rebreathing CO from endogenous sources or both). However, these findings suggest that avoidance of low-flow anesthesia will prevent rebreathing of exhaled CO, and use of carbon dioxide absorbents that lack strong metal hydroxide could limit inspired CO if detection was attributable to degradation of volatile anesthetic.

ACC/AHA/ASE/HRS/ISACHD/SCAI/SCCT/SCMR/SOPE 2020 Appropriate Use Criteria for Multimodality Imaging During the Follow-Up Care of Patients With Congenital Heart Disease: A Report of the American College of Cardiology Solution Set Oversight Committee and Appropriate Use Criteria Task Force, American Heart Association, American Society of Echocardiography, Heart Rhythm Society, International Society for Adult Congenital Heart Disease, Society for Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance, and Society of Pediatric Echocardiography.

The American College of Cardiology (ACC) collaborated with the American Heart Association, American Society of Echocardiography, Heart Rhythm Society, International Society for Adult Congenital Heart Disease, Society for Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance, and the Society of Pediatric Echocardiography to develop Appropriate Use Criteria (AUC) for multimodality imaging during the follow-up care of patients with congenital heart disease (CHD). This is the first AUC to address cardiac imaging in adult and pediatric patients with established CHD. A number of common patient scenarios (also termed "indications") and associated assumptions and definitions were developed using guidelines, clinical trial data, and expert opinion in the field of CHD.1 The indications relate primarily to evaluation before and after cardiac surgery or catheter-based intervention, and they address routine surveillance as well as evaluation of new-onset signs or symptoms. The writing group developed 324 clinical indications, which they separated into 19 tables according to the type of cardiac lesion. Noninvasive cardiac imaging modalities that could potentially be used for these indications were incorporated into the tables, resulting in a total of 1,035 unique scenarios. These scenarios were presented to a separate, independent panel for rating, with each being scored on a scale of 1 to 9, with 1 to 3 categorized as "Rarely Appropriate," 4 to 6 as "May Be Appropriate," and 7 to 9 as "Appropriate." Forty-four percent of the scenarios were rated as Appropriate, 39% as May Be Appropriate, and 17% as Rarely Appropriate. This AUC document will provide guidance to clinicians in the care of patients with established CHD by identifying the reasonable imaging modality options available for evaluation and surveillance of such patients. It will also serve as an educational and quality improvement tool to identify patterns of care and reduce the number of Rarely Appropriate tests in clinical practice.

Direction of preoperative ventricular shunting affects ventricular mechanics after Tetralogy of Fallot repair.

BACKGROUND: Tetralogy of Fallot (TOF) typically results in clinical cyanosis or volume overload of the left ventricle (LV), depending on the direction and magnitude of shunting across the ventricular septal defect (VSD). The present study examines the effects of surgical TOF repair on LV mechanics and compares these changes between patients with VSD shunts that are predominantly right-to-left (R-L; "blue TOF") and those with VSD shunts that are predominantly left-to-right (L-R; "pink TOF"). METHODS AND RESULTS: Eleven patients (6 R-L and 5 L-R) 4.3 to 18.4 months old (median 7.1 months old) were studied. LV end-diastolic area (EDA) was calculated from transesophageal echocardiograms obtained during initiation and weaning of cardiopulmonary bypass. LV end-diastolic pressure was measured by micromanometer. Compliance was assessed by end-diastolic pressure-area curves. Contractility was assessed from preload recruitable stroke work by the stroke work-versus-LV EDA relation. VSD shunt direction was determined by preoperative Doppler echocardiography. Changes in LV function at the conclusion of cardiopulmonary bypass included decreased stroke area (from 6.6 +/- 0.9 to 4.1 +/- 0.4 cm(2)/m(2), P=0.012) and ejection fraction (from 55 +/- 2% to 41 +/- 3%, P<0.001). LV EDA at a common pressure in 8 patients decreased (from 10.4 +/- 1.4 to 7.6 +/- 1.2 cm(2)/m(2), P=0.003), which suggests a decrease in ventricular compliance. Additionally, the end-diastolic pressure-area curves shifted to the left in all patients. Preload recruitable stroke work decreased (from 34.8 +/- 2.4 to 21.8 +/- 2.6 mm Hg, P=0.007), which demonstrates a decrease in ventricular contractility. When separated by preoperative shunt direction, LV EDA increased in R-L patients by 0.9+/-0.5 cm(2)/m(2) postoperatively but decreased in L-R patients by 4.3 +/- 0.8 cm(2)/m(2) (P<0.001). Area ejection fraction decreased in all patients independent of shunting or change in LV EDA. CONCLUSIONS: LV diastolic and systolic function are depressed after TOF repair. Mechanical effects of the VSD patch and myocardial depressant effects of ischemia and reperfusion during surgery probably contribute to the observed changes in LV mechanics. Different effects of surgical repair on LV preload in pink and blue TOF also contribute to the spectrum of clinical results observed after surgery.

Risk Factors for Major Early Adverse Events Related to Cardiac Catheterization in Children and Young Adults With Pulmonary Hypertension: An Analysis of Data From the IMPACT (Improving Adult and Congenital Treatment) Registry.

BACKGROUND: Cardiac catheterization is the gold standard for assessment and follow-up of patients with pulmonary hypertension (PH). To date, there are limited data about the factors that influence the risk of catastrophic adverse events after catheterization in this population. METHODS AND RESULTS: A retrospective multicenter cohort study was performed to measure risk of catastrophic adverse outcomes after catheterization in children and young adults with PH and identify risk factors for these outcomes. All catheterizations in children and young adults, aged 0 to 21 years, with PH at hospitals submitting data to the IMPACT (Improving Adult and Congenital Treatment) registry between January 1, 2011, and December 31, 2015, were studied. Using mixed-effects multivariable regression, we assessed the association between prespecified subject-, procedure-, and center-level covariates and the risk of death, cardiac arrest, or mechanical circulatory support during or after cardiac catheterization. A total of 8111 procedures performed in 7729 subjects at 77 centers were studied. The observed risk of the composite outcome was 1.4%, and the risk of death before discharge was 5.2%. Catheterization in prematurely born neonates and nonpremature infants was associated with increased risk of catastrophic adverse event, as was precatheterization treatment with inotropes and lower systemic arterial saturation. Secondary analyses demonstrated the following: (1) increasing volumes of catheterization in patients with PH were associated with reduced risk of composite outcome (odds ratio, 0.8 per 10 procedures; P=0.002) and (2) increasing pulmonary vascular resistance and pulmonary artery pressures were associated with increased risk (P<0.0001 for both). CONCLUSIONS: Young patients with PH are a high-risk population for diagnostic and interventional cardiac catheterization. Hospital experience with PH is associated with reduced risk, independent of total catheterization case volume.

Transcatheter Treatment of Thrombosis in the Single Ventricle Pathway: An Institutional Experience.

BACKGROUND: Shunt or conduit thrombosis in a single ventricle circuit is a life-threatening complication that requires prompt treatment to rapidly restore shunt/conduit patency. Transcatheter interventions represent an attractive alternative to systemic thrombolysis or open surgical procedures. We report our center's experience with catheter-based approaches in patients with palliated single ventricle who present with shunt/conduit thrombosis. METHODS: A retrospective review was performed of all patients with palliated single ventricle physiology who were diagnosed over a 5-year period with shunt/conduit thrombosis and received catheter-based interventions. Patients were followed up to hospital discharge. RESULTS: Thirteen patients were identified that were diagnosed with thrombosis of a modified Blalock-Taussig shunt (five patients), bidirectional cavopulmonary shunt (one patient), and total cavopulmonary pathway (seven patients). Shunt/conduit thrombosis occurred both early and late after palliation surgery. Catheter-based interventions included balloon angioplasty (one patient), stent implantation (12 patients), and mechanical thrombectomy (one patient). Thrombophilia was identified in seven patients. Technical and clinical success with restoration of normal shunt flow and improvement in clinical status was achieved in 12 patients. Reversible procedure-related complications occurred in three patients with no significant sequelae. CONCLUSIONS: Our experience suggests that percutaneous catheter-based interventions are safe and effective in managing shunt/conduit thrombosis in infants and children with palliated single ventricle circulation.

Hybrid Exclusion of HeartMate ІІ Left Ventricular Assist Device After Bridge to Recovery.

We present a hybrid technique of left ventricular assist device exclusion after bridge to recovery in a pediatric patient, using percutaneous occlusion of the outflow graft and surgical excision of driveline. This technique has the advantage of avoiding chest reentry and cardiopulmonary bypass.

Recent advances in non-interventional pediatric cardiac catheterization.

PURPOSE OF REVIEW: The role of cardiac catheterization in pediatric cardiology has changed significantly in the past 10-15 years. As interventional procedures dominate the field, it is important to examine the recent advances in non-interventional pediatric cardiac catheterization. RECENT FINDINGS: Meaningful and accurate data must be acquired for the presurgical evaluation of patients with congenital heart disease to better guide clinical decisions. In particular, all patients with single- ventricle physiology currently undergo diagnostic catheterization before bidirectional Glenn and Fontan surgeries. Recent studies are beginning to identify a subset of these patients who may not need to undergo presurgical catheterization. As surgical techniques evolve, diagnostic catheterization has a role in the analysis of hemodynamic variables and clinical outcomes. This can be seen in recent papers that examine the Sano modification to the Norwood procedure.Recent papers demonstrate the continued development of new techniques, new technology, and a progression towards smaller equipment. The use of conductance catheters, Doppler flow wires, and smaller traditional catheters will allow the pediatric cardiologist to more accurately and safely evaluate hemodynamic parameters. SUMMARY: Non-interventional pediatric cardiac catheterization continues to have an important role in the assessment and treatment of patients with congenital heart disease.

Optimized perioperative biventricular pacing in setting of right heart failure.

AIMS: A 78-year-old female with prior atrioventricular junctional ablation for paroxysmal atrial fibrillation and implantation of DDDR pacemaker underwent repair of severe tricuspid insufficiency. Effects of biventricular pacing were tested with temporary wires at the conclusion of cardiopulmonary bypass. METHODS: An ultrasonic flow probe was placed on the ascending aorta for real time cardiac output measurements. Atrioventricular delay optimization was performed and biventricular pacing was initiated while right-left ventricular delays were varied. RESULTS: There was no advantage of biventricular pacing (optimum right-left ventricular delay of +80 ms) compared with existing DDD. CONCLUSIONS: This study confirms the physiological effects of right-left ventricular delay on cardiac output after cardiopulmonary bypass.

Optimized biventricular pacing in atrioventricular block after cardiac surgery.

BACKGROUND: Temporary pacing is required after open-heart surgery for treatment of heart block. Atrioventricular delay and ventricular pacing site might be manipulated to increase cardiac output. We hypothesized that by optimizing both atrioventricular delay and ventricular pacing site a 10% improvement in cardiac output would be observed compared with a standard pacing protocol. METHODS: Seven patients in first or third degree heart block after valve replacement surgery had temporary wires sewn to the right atrium, right ventricle, and left ventricle. Cardiac output was measured by integrating flow velocity from an ultrasonic aortic flow probe. After optimization of atrioventricular delays during atrial synchronous right ventricular pacing, the effects of ventricular pacing site were tested at the optimum atrioventricular delay for 10-second intervals. RESULTS: Biventricular pacing was beneficial in all patients with a mean increase of 22% in cardiac index over right ventricular pacing (1.95 L/min/m2 +/- 0.27 standard error of the mean (SEM) to 2.38 L/min/m2 +/- 0.27 SEM, p = 0.0012) and 14% over left ventricular pacing (2.08 L/min/m2 +/- 0.22 SEM to 2.38 L/min/m2 +/- 0.27 SEM, p = 0.0133). Comparing optimized with standard pacing for 30-second intervals yielded a mean increase of 10% in cardiac index over three respiratory cycles (2.87 L/min/m2 +/- 0.33 SEM to 2.60 L/min/m2 +/- 0.37 SEM, p = 0.009) and 17% at the corresponding end-expiratory beats (2.76 L/min/m2 +/- 0.33 SEM to 2.36 L/min/m2 +/- 0.36 SEM, p = 0.011). CONCLUSIONS: Biventricular pacing at optimum atrioventricular delay improves cardiac output in patients with postoperative heart block by at least 10% compared with standard pacing.

Transcatheter closure of a very large patent ductus arteriosus in a pregnant woman at 22 weeks of gestation.

Successful transcatheter closure of a large PDA in a pregnant patient is reported using the Amplatzer ductal occluder device. This procedure was safe and uncomplicated, obviating the need for surgery in this high risk patient.