Left ventricular form and function: scientific priorities and strategic planning for development of new views of disease.
Explore the source record for details and available documents.
Aging↗
Biomedical subjects
David J Sahn
Publications and source records attributed to David J Sahn.
Fetal ventricular mass determination on three-dimensional echocardiography: studies in normal fetuses and validation experiments.
BACKGROUND: Estimation of ventricular volume and mass is important for baseline and serial evaluation of fetuses with normal or abnormal hearts. Direct measurement of chamber wall volumes and mass can be made without geometric assumptions by 3D fetal echocardiography. Our goals were to determine the feasibility of using fast nongated 3D echocardiography for fetal volumetric and mass assessments, to validate the accuracy of the ultrasound system and the measurement technique, and if satisfactory, to develop normal values for fetal ventricular mass during the second and third trimesters. METHODS AND RESULTS: This was a prospective outpatient study of 90 consecutive normal pregnancies during routine obstetric services at Oregon Health & Science University (Portland). Optimized 3D volumes of the fetal thorax and cardiac chambers were rapidly acquired and later analyzed for right and left ventricular mass by radial summation technique from manual epicardial and endocardial traces. Experiments to validate the ultrasound system and measurement technique were performed with modified small balloon models and in vivo and ex vivo small animal experiments. Our study established the feasibility of fetal ventricular mass measurements with 3D ultrasound technology and developed normal values for right and left ventricular mass from 15 weeks' gestation to term. CONCLUSIONS: Nongated fast 3D fetal echocardiography is an acceptable modality for determination of cardiac chamber wall volume and mass with good accuracy and acceptable interobserver variability. The method should be especially valuable as an objective serial measurement in clinical fetal studies with structurally or functionally abnormal hearts.
Animals↗
Biphasic left ventricular outflow and its mechanism in hypertrophic obstructive cardiomyopathy.
BACKGROUND: Biphasic systolic velocity in the left ventricular (LV) outflow tract (LVOT) occurs in hypertrophic obstructive cardiomyopathy (HOCM). The cause and importance of this observation remain poorly understood. METHODS: A total of 25 patients with HOCM were matched to 30 control subjects. A function derived from the relation of flow in the proximal descending aorta to that in the LVOT was used to estimate the LVOT systolic flow rate in HOCM. Patients with HOCM were grouped by absence (group I) or presence (group II) of biphasic LVOT velocity. RESULTS: Biphasic LVOT velocity was associated with biphasic estimated LVOT outflow (P =.002). The LVOT pressure gradient was inversely related to LV outflow rate at the time of the peak gradient (r = -.64, P <.001). Dobutamine increased the gradient and reduced LVOT outflow at the time of the peak gradient. In group II, mitral-septal separation occurred despite a LVOT gradient (36 mm Hg). CONCLUSION: Biphasic LVOT flow in HOCM occurs and may be caused by "afterload mismatch." The late systolic increase in flow is related to mitral-septal separation. Resolution of systolic anterior motion occurs despite a persistent LVOT pressure gradient, implying a role for forces other than pressure differences.
Adrenergic beta-Agonists↗
Real-time 3-dimensional echocardiography for quantification of the difference in left ventricular versus right ventricular stroke volume in a chronic animal model study: Improved results using C-scans for quantifying aortic regurgitation.
OBJECTIVE: The purpose of our study was to test the applicability of calculating the difference between left ventricular (LV) and right ventricular (RV) stroke volume (SV) for assessing the severity of aortic (Ao) regurgitation (AR) using a real-time 3-dimensional (3D) echocardiographic (RT3DE) imaging system. METHODS: The Ao valve was incised in 5 juvenile sheep, 6 to 10 weeks before the study, to produce AR (mean regurgitant fraction = 0.50). Simultaneous hemodynamic and RT3DE images were obtained on open-chest animals with Ao and pulmonary flows derived by Ao and pulmonary electromagnetic flowmeters balanced against each other. Four stages (baseline, volume loading, sodium nitroprusside, and angiotensin infusion) were used to produce a total of 16 different hemodynamic states. Epicardial scanning was done with a 2.5-MHz probe to sequentially record first the RV and then the LV cavities. Cavity volumes from the 3D echocardiography data were determined from angled sector planes (B-scans) and parallel cutting planes (C-scans, which are planes perpendicular to the direction of the volume interrogation). AR volumes were determined from 3D images by computing and then subtracting RV SVs from LV SVs and then these were compared with electromagnetic flowmeter-derived SV and regurgitant volumes. RESULTS: There was close correlation between RV and LV SVs of the RT3DE and electromagnetic methods (C-scans: LV, r = 0.98, standard error of the estimate [SEE] = 2.62 mL, P =.0001; RV, r = 0.89, SEE = 2.67 mL, P <.0001; and B-scans: LV, r = 0.95, SEE = 3.55 mL, P =.0001; RV, r = 0.77, SEE = 2.78 mL, P =.0003). Because of the small size of the RV in this model, the correlation was closer for C-scans than B-scans for RV SV. AR volume estimation also showed that C-scan (r = 0.93, SEE = 4.23 mL, P <.0001) had closer correlation than B-scan (r = 0.89, SEE = 4.87 mL, P <.0001). However, B-scan-derived AR fraction showed closer correlation than did C-scan (r = 0.82 vs r = 0.85, respectively). CONCLUSION: In this animal model, RT3DE imaging had the ability to reliably quantify both LV (B- and C-scans) and RV SVs and to assess the severity of AR.
Animals↗
Imaging of the aorta.
The aorta is an integral part of the cardiovascular system and should not be considered as just a conduit for blood supply from the heart to the limbs and major organs. A range of important pathologies affect the aorta and are responsible for a high level of morbidity and mortality in affected patients. Many of these conditions are seen in the adult congenital population, especially as advances in diagnosis and treatment mean these patients are surviving well into adulthood. As we gain a greater understanding of these disorders, especially the underlying genetics and pathophysiology, it becomes clear that the aorta is a highly complex part of the vascular tree. As such, the aorta requires increasingly sophisticated imaging techniques for the diagnosis, treatment and follow-up of these patients. The advantages and disadvantages of the various imaging techniques available to clinicians will be discussed in the context of both acute and chronic aortic pathology.
Aortic Dissection↗
Risk of sudden cardiac death in young athletes: which screening strategies are appropriate?
Resources are not available to comprehensively evaluate all young athletes before participation in competitive sports. Therefore, the cardiovascular evaluation of young athletes needs to be targeted at high-risk areas and focus on the individuals who are at greatest possible risk: those who have suggestive, even if minor, symptoms, and those who have a family history of sudden death or premature cardiac disease.
Adolescent↗
Latest advances and topics in fetal echocardiography.
PURPOSE OF REVIEW: Fetal diagnosis and the supporting specialties of perinatology, neonatology, and surgery have made rapid strides in the last decade. Numerous centers are focusing on this multifaceted niche area as the medical field realizes its vast promise and potential. The authors review some of the major advancements in thought and practice in the field of fetal echocardiography while attempting to give a less detailed overview for the less involved perinatologist. RECENT FINDINGS: First trimester fetal echocardiography has been an area of recent interest as transducer technology improves. As a result, optimum timing of first and subsequent scans and the population profile they are to be applied to have become an issue that begs consensus. Three-dimensional and four-dimensional fetal echocardiography have also received a boost for the same reasons, and both are being studied for feasibility and accuracy. Fetal tissue Doppler and spectral Doppler imaging are potential areas for exploration; the early steps have been taken. Awareness of associated ultrasound markers, such as exaggerated nuchal translucency, as clues to the presence of congenital heart disease is important, even if controversial. SUMMARY: The issue of missed prenatal diagnosis is disturbing, especially when it arises against a background of tremendous skill and technologic support. Strategies to minimize mistakes in this critical aspect need to be agreed on by the involved teams and put in place in a multidisciplinary manner if they are to have an important impact.
Echocardiography↗
Congenital heart disease never goes away, even when it has been 'treated': the adult with congenital heart disease.
PURPOSE OF REVIEW: As the specialties of pediatrics and pediatric cardiology continue to forge ahead with better diagnoses, medical care, and surgical results, an expanding population of patients with congenital heart disease (CHD) outgrows the pediatric age group, yet does not quite graduate to routine adult cardiology or general medicine. The adult with congenital heart disease (ACHD) faces medical, surgical, and psychosocial issues that are unique to this population and must be addressed as such. This review attempts to discuss and highlight some of the important advances and controversies brought up in the past year, in the care and management of these patients. RECENT FINDINGS: The past five to 10 years have seen dynamic interest in understanding sequelae of corrected, uncorrected, or palliated congenital heart disease. The search for the ideal surgery, optimal prosthesis, and a smooth transition to adult care continues and is reflected in the vast amount of academic work and publications in this field. Of particular interest, conduit reoperations and single ventricle pathway modifications are still an art and a science in evolution. SUMMARY: While all are agreed that there is a pressing need to focus on the delivery of care to the adult with congenital heart disease, this essentially requires a clearer understanding of late sequelae of CHD. The sheer heterogeneity of anatomy, age, surgery, and institutional management protocols can make it difficult to develop clear guidelines. This review attempts to give an up-to-date perspective on some of the new findings related to the more common lesions and problems faced in this group.
Adult↗
Determination of asymmetric cavity volumes using real-time three-dimensional echocardiography: an in vitro balloon model study.
OBJECTIVES: We designed a new in vitro model to test the accuracy and reproducibility of real-time three-dimensional (RT3D) ultrasound imaging for determining a variety of asymmetric cavity volumes with aneurysm. METHODS: Fifteen individual balloon models mimicking ventricular aneurysm were filled with water (170-322.5 ml) without air bubbles and kept in a compressor pump. Compression of the models produced only a change in shape of the balloon and no change in volume. The models were scanned with RT3D echocardiography (RT3DE) and the images recorded on an optical disk. Volumes were measured off line in two phases; maximal compression, where there was maximal change in shape and nil compression, where there was minimal or no change in shape. Volumes were measured by manual tracing technique of the inner border of B-scan images and compared with the drained volume of water from the balloon. RESULTS: There was a high correlation between the drained volume and measured volume at maximal compression (equivalent to end-systole, r = 0.99, y = 0.99x + 3.69, SEE = 6.5 ml), between the drained volume and measured volume at nil compression (equivalent to end-diastole, r = 0.99, y = 0.94x + 12.07, SEE = 5.9 ml), and between volumes measured at maximal and nil compressions (r = 0.99, y = 0.94x + 10.55, SEE = 4.6 ml). CONCLUSION: The results of this experiment show that RT3DE can accurately measure the volumes of a variety of asymmetric ventricular cavities.
Cardiac Volume↗
Validation of volume and mass assessments for human fetal heart imaging by 4-dimensional spatiotemporal image correlation echocardiography: in vitro balloon model experiments.
OBJECTIVE: This study was designed to validate a slow-sweep real-time 4-dimensional (4D) spatiotemporal image correlation method for producing quantitatively accurate dynamic fetal heart images using an in vitro pulsatile balloon model and apparatus. METHODS: To model fetal heart chambers, asymmetric double-walled finger stalls (tips of surgical latex gloves) were used and attached to a laboratory-designed circuit that allowed calibrated changes in the inner balloon volume as well as an intermediate gel mass interposed between the 2 layers. The water-submerged model was attached to a small-volume pulsatile pump to produce phasic changes in volume within the inner balloon at a fixed rate. A sonography system with 4D spatiotemporal image correlation (STIC) capabilities was used for 3-dimensional (3D) and 4D data acquisition. Volume data were analyzed by customized radial summation techniques with 4D data analysis software and compared with known volumes and masses. RESULTS: Fifty-six individual volumes ranging from 2.5 to 10 mL were analyzed. Volume and mass measurements with 4D STIC were highly correlated (R2 > 0.90). The mean percentage error was better (<6%) for volumes exceeding 4 mL and was as low as 0.3% for 6-mL estimations. Measurements in the diastolic phase were the most accurate, followed by mass estimations equivalent to chamber walls. There was a wider range of percentage error in the lowest volumes tested (2.5 mL), which might have arisen from difficulties in spatial resolution or distortions from within the model apparatus itself. Resolution limitations of 4D technology in combination with extremely small volume targets may explain higher error rates at these small volumes. CONCLUSIONS: Four-dimensional STIC is an acceptably accurate method for volume and mass estimations in the ranges comparable with mid- and late-gestation fetal hearts. It is particularly accurate for diastolic estimations, for chamber wall mass measurements, and at volumes of greater than 2.5 mL. This study validates use of 4D STIC technology to overcome the limitations of nongated 3D technology for phasic and quantitative assessments in fetal echocardiography.
Echocardiography, Four-Dimensional↗
Myocardial strain rate is a superior method for evaluation of left ventricular subendocardial function compared with tissue Doppler imaging.
OBJECTIVES: This study was performed to evaluate subendocardial function using strain rate imaging (SRI). BACKGROUND: The subendocardium and mid-wall of the left ventricle (LV) play important roles in ventricular function. Previous methods used for evaluating this function are either invasive or cumbersome. Strain rate imaging by ultrasound is a newly developed echocardiographic modality based on tissue Doppler imaging (TDI) that allows quantitative assessment of regional myocardial wall motion. METHODS: We examined eight sheep using TDI in apical four-chamber views to evaluate the LV free wall. Peak strain rates (SRs) during isovolumic relaxation (IR), isovolumic contraction (IC), and myocardial strain were measured in the endocardial (End), mid-myocardial (Mid), and epicardial (Epi) layers. For four hemodynamic conditions (created after baseline by blood, dobutamine, and metoprolol infusion), we compared differences in SR of End, Mid, and Epi layers to peak positive and negative first derivative of LV pressure (dP/dt). RESULTS: Strain rate during IC showed a good correlation with +dP/dt (r = 0.74, p < 0.001) and during IR with -dP/dt (r = 0.67, p = 0.0003). There was a significant difference in SR between the myocardial layers during both IC and IR (End: -3.4 +/- 2.2 s(-1), Mid: -1.8 +/- 1.5 s(-1), Epi: -0.63 +/- 1.0 s(-1), p < 0.0001 during IC; End: 2.2 +/- 1.5 s(-1), Mid: 1.0 +/- 0.8 s(-1), Epi: 0.47 +/- 0.64 s(-1), p < 0.0001 during IR). Also, SRs of the End and Mid layers during IC were significantly altered by different hemodynamic conditions (End at baseline: 1.7 +/- 0.7 s(-1); blood: 2.0 +/- 1.1 s(-1); dobutamine: 3.4 +/- 2.3 s(-1); metoprolol: 1.0 +/- 0.4 s(-1); p < 0.05). Myocardial strain showed differences in each layer (End: -34.3 +/- 12.6%; Mid: -22.6 +/- 12.1%; Epi: -11.4 +/- 7.9%; p < 0.0001) and changed significantly in different hemodynamic conditions (p < 0.0001). CONCLUSIONS: Strain and SR appear useful and sensitive for evaluating myocardial function, especially for the subendocardial region.
Animals↗
What is the most effective method of detecting anomalous coronary origin in symptomatic patients?
Explore the source record for details and available documents.
Child↗
Will a handheld ultrasound scanner be applicable for screening for heart abnormalities in newborns and children?
BACKGROUND: There is significant interest in opportunities to provide echocardiography services for detection of congenital heart disease with portable, or even handheld, devices in remote areas or third world countries where conventional ultrasound systems may not be available. We tested a handheld system (HHS) (SonoHeart, SonoSite Inc, Bothell, Wash) equipped with a broadband, 7- to 4-MHz, miniaturized, curved, linear-array transducer and implemented with an improved directional Doppler flow map. METHODS: All echocardiography scanning was performed in the neonatal nursery, pediatric intensive care department, or pediatric echocardiography laboratory of our institution. We reviewed limited echocardiography view sequences sequentially obtained by the same expert examiner (D.J.S.) in 50 infants and children (age: 1 day to 6 years), with preoperative or postoperative forms of congenital heart disease. Each patient was studied twice, once with a conventional full-feature system (FFS) and then a limited scan with the HHS using similar frequency transducers. The cardiologist (D.J.S.) and blinded research laboratory reviewers (X.L., G.K.M., R.A.R.) read the FFS and HHS image sequences for diagnosis and for grading the quality of the anatomic and flow feature images. The studies were performed and reviewed with the examiner and reviewers blinded to patient diagnosis. RESULTS: The major diagnoses (eg, patent ductus arteriosus, atrio-ventricular (AV) canal, peripheral pulmonary valve stenosis, aortic coarctation, atrial septal defect, ventricular septal defect, preoperative or postoperative tetralogy of Fallot, and mitral regurgitation) were made by both readers, who were unaware of each other's diagnosis results. Furthermore, the average composite HHS cardiac anatomic feature score on a scale of 0 (not visualized) to 3 (visualized precisely) from the parasternal long-axis and 4- or 5-chamber view for cardiac anatomy were 2.67 +/- 0.49 (SD) and 2.50 +/- 0.55, respectively, versus 2.73 +/- 0.45 and 2.55 +/- 0.54 for the FFS. The mean flow feature score, comprising all views, was 2.67 +/- 0.45 (HHS) versus 2.72 +/- 0.48 (FFS). The P values for all above comparisons were >.05. Image quality of the FFS anatomic structures were, thus, not statistically different from the HHS. Although the color cosmetic was different for the HHS directional (nonvelocity) map, only 9% of 150 total findings (including structural abnormalities and flow features, none of which were critical) were missed, whereas the other 91% regurgitant, shunt, stenosis flow features or heart structure were imaged adequately by the HHS in this population. CONCLUSIONS: Implementing high-frequency transducers and programs optimized for tissue and flow imaging on the HHS should provide images of sufficient quality for targeted echocardiography examinations to determine the presence, absence, or status of congenital heart disease in newborns and young children.
Aortic Valve↗
Lower receiving frequencies than transmitting frequencies could yield improved results for contrast imaging: an in vivo study in closed chest canines.
BACKGROUND: Ultrasonic imaging methods of receiving at higher frequencies, which are multiples of the transmitting frequencies (harmonic imaging), are well established as a means of improving myocardial visualization in association with intravenous contrast administration. This exploratory study examined the effect of using receive frequencies that were lower than the transmit frequencies while imaging closed chest dogs with an Ensemble wideband, phase inversion contrast program on a modified Siemens Elegra scanner. METHODS: Intravenous bolus injections of 0.75 mL Definity and 1 mL QW7437 were administered to six anesthetized dogs. Intermittent imaging for contrast visualization was performed using either a broadband array, transmitting at 1.4 MHz and receiving at 2.6-3.2 MHz or a broadband 4-7.5 MHz transducer transmitting at 6.0 MHz and receiving at 4.2-4.5 MHz. Contrast enhancement was measured by videodensitometry, sampling mid-cavity and within the myocardium before and after injection. The changes in videodensity from control to after injection were calculated for each method. RESULTS: There was no significant difference in the change in intracavity videodensity between the two imaging strategies although there was near full intracavity saturation in all cases. However, the change in myocardial density was significantly greater for both contrast agents when using receiving frequencies lower than transmitting frequencies (P = 0.02 and 0.03). The difference in duration of the myocardial blush did not reach statistical significance but it tended to persist for longer with the lower receiving frequencies. CONCLUSION: Delivering sound energy at a slightly higher frequency and receiving at lower than the transmit frequency may be an advantageous method of enhancing myocardial perfusion signals during intravenous contrast echocardiography.
Animals↗
Strain rate acceleration yields a better index for evaluating left ventricular contractile function as compared with tissue velocity acceleration during isovolumic contraction time: an in vivo study.
OBJECTIVE: Our study aimed to investigate whether strain rate acceleration (SRA) during isovolumic contraction time (IVCT) could serve as a sensitive indicator of myocardial function. METHODS: A total of 8 sheep underwent occlusion of left anterior descending coronary artery or diagonal branches and 2 sheep underwent left circumflex coronary artery occlusion to create septal, apical, or basal segment myocardial ischemia 19 to 27 weeks before the study. Baseline, volume-loading, dobutamine, and metoprolol infusion were used to produce 4 hemodynamic stages for each sheep. Doppler tissue imaging was acquired using a 5-MHz probe (GE/VingMed Vivid Five, GE Medical Systems, Milwaukee, Wis) on open-chest animals using the liver as a standoff at the apex. Using software (EchoPac, GE Medical Systems), SRA during IVCT was calculated and compared with tissue velocity acceleration (TVA) during IVCT from areas located in the normal and ischemic zones. Also, invasively monitored left ventricle dP/dt was measured as reference contractile function. RESULTS: Both TVA and SRA during IVCT showed higher values for normal tissue than for ischemic area (P <.0001). SRA for normal wall segments changed significantly during the 4 stages (P =.01) with corresponding changes on high-fidelity left ventricular pressure catheters (r = 0.92). TVA over normal segments showed no significant change (P =.29) in the 4 hemodynamic stages. Both TVA and SRA of the ischemic segments showed no significant change with pharmacologic maneuvers or loading conditions. CONCLUSIONS: SRA and TVA during IVCT are both useful indicators for detecting abnormal heart wall motion. However, SRA tends to be more sensitive than TVA for differentiating the response to stress conditions.
Animals↗
A new dynamic three-dimensional digital color doppler method for quantification of pulmonary regurgitation: validation study in an animal model.
OBJECTIVES: The purpose of the present study was to validate a newly developed three-dimensional (3D) digital color Doppler method for quantifying pulmonary regurgitation (PR), using an animal model of chronic PR. BACKGROUND: Spectral Doppler methods cannot reliably be used to assess pulmonary regurgitation. METHODS: In eight sheep with surgically created PR, 27 different hemodynamic states were studied. Pulmonary and aortic electromagnetic (EM) probes and meters were used to provide reference right ventricular (RV) forward and pulmonary regurgitant stroke volumes. A multiplane transesophageal probe was placed directly on the RV and aimed at the RV outflow tract. Electrocardiogram-gated and rotational 3D scans were performed for acquiring dynamic 3D digital velocity data. After 3D digital Doppler data were transferred to a computer workstation, the RV forward and pulmonary regurgitant flow volumes were obtained by a program that computes the velocity vectors over a spherical surface perpendicular to the direction of scanning. RESULTS: Pulmonary regurgitant volumes and RV forward stroke volumes computed by the 3D method correlated well with those by the EM method (r = 0.95, mean difference = 0.51 +/- 1.89 ml/beat for the pulmonary regurgitant volume; and r = 0.91, mean difference = -0.22 +/- 3.44 ml/beat for the RV stroke volume). As a result of these measurements, the regurgitant fractions derived by the 3D method agreed well with the reference data (r = 0.94, mean difference = 2.06 +/- 6.11%). CONCLUSIONS: The 3D digital color Doppler technique is a promising method for determining pulmonary regurgitant volumes and regurgitant fractions. It should have an important application in clinical settings.
Animals↗
Strain rate imaging: an in vitro "validation" study using a physiologic balloon model mimicking the left ventricle.
BACKGROUND: Strain rate imaging (SRI) can be implemented from digital ultrasound loops of tissue Doppler imaging (TDI) data and is performed as an autocorrelation solution of the distance between intramyocardial targets. As such, it should have better resolution along longer distances of wall segments that are imaged at the length of individual ultrasound scan lines. METHODS: We used a new left ventricular double-balloon phantom with a tissue-mimicking gel between the walls. Mounted in a water bath and connected to a pulsatile flow pump at four-stroke volume (30-50 ml/beat), the high frame rate, digital, multiple two-dimensional/tissue/TDI loops of balloon wall motion were recorded using a GE VingMed system FiVe (3.5 MHz phased array transducer), with the model scanned longitudinally from the apex. The strain rate (SR) values were measured at the apex and the lateral wall using an offline measurement program, and mean SR values for every 100 msec were calculated by averaging three determinations at each point. The excursions of the apex and lateral wall also were measured directly by high speed digital video imaging, and consecutive velocity profiles were calculated every 100 msec. A total of 40 data points for four-stroke volumes were analyzed. RESULTS: While our balloon model had enough gel targets between the walls to produce a good mimic of myocardial speckle with walls that thickened and thinned, samples immediately across the apex and apex SR values (Hz) varied substantially. In contrast, systematic signals could be obtained from lines imaged >15 degrees from the true apex and crossing a longer length of myocardium. At the lateral wall, there was a close correlation between the video velocities and SR values, as well as a close overlap of the phasic patterns. CONCLUSIONS: SRI produces more reliable data from wall segments parallel to scan lines.
Blood Flow Velocity↗
New technology and methodologies for intraoperative, perioperative, and intraprocedural monitoring of surgical and catheter interventions for congenital heart disease.
We review the new technology and methods available for support of intraoperative and intraprocedural imaging in the catheterization laboratory for surgical and interventional catheterization procedures in the treatment of congenital heart disease. The methods reviewed include miniaturized probes and new ways of using them perioperatively for cardiac imaging from transesophageal, substernal, and intracardiac imaging locations. The smaller and more versatile the probes, the better adapted they will be in providing methods to improve the outcomes in babies born with serious forms of congenital heart disease.
Cardiac Surgical Procedures↗