Short-axis Approach Research Articles

Cardiac Magnetic Resonance Imaging and the Assessment of Ebstein Anomaly in Adults

No published studies have evaluated the role of cardiac magnetic resonance (CMR) imaging for the assessment of Ebstein anomaly. Our objective was to evaluate the right heart characteristics in adults with unrepaired Ebstein anomaly using contemporary CMR imaging techniques. Consecutive patients with unrepaired Ebstein anomaly and complete CMR studies from 2004 to 2009 were identified (n = 32). Volumetric measurements were obtained from the short-axis and axial views, including assessment of the functional right ventricular (RV) end-diastolic volume (EDV) and end-systolic volume. The volume of the atrialized portion of the right ventricle in end-diastole was calculated as the difference between the total RVEDV and the functional RVEDV. The reproducibility of the measurements in the axial and short-axis views was determined within and between observers. The median value derived from the short-axis and axial views was 136 ml/m(2) (range 59 to 347) and 136 ml/m(2) (range 63 to 342) for the functional RVEDV, 153 ml/m(2) (range 64 to 441) and 154 ml/m(2) (range 67 to 436) for the total RVEDV, 49% (range 32% to 46%) and 50% (range 40% to 64%) for the functional RV ejection fraction, respectively. The axial measurements demonstrated lower intraobserver and interobserver variability than the short-axis approach for all values, with the exception of the intraobserver functional RVEDV and interobserver total RVEDV for which the limits of agreement and variance were not significantly different between the 2 views. In conclusion, measurements of right heart size and systolic function in patients with Ebstein anomaly can be reliably achieved using CMR imaging. Axial imaging appeared to provide more reproducible data than that obtained from the short-axis views.

Assessment of left ventricular function: visual or quantitative?

Assessment of cardiac function continues to be an important issue in patients with assumed left ventricular (LV) dysfunction [1–10]. In particular in patients with enlarged left ventricles, such as occurs in ischemic and idiopathic dilated cardiomyopathy, accurate assessment of LV function remains pivotal [11–14]. To assess myocardial function, different diagnostic methods are currently performed such as echocardiography, single photon emission computed tomography (SPECT), and cardiac magnetic resonance imaging (CMR) [15–23]. In the clinical arena, detection of myocardial function is predominantly based on echocardiographic studies. In addition, nuclear techniques, showing preserved tracer uptake and metabolism in viable myocardium, may also assess left ventricular function and wall motion. Volumetric analysis by gated SPECT imaging offers considerable additional value to SPECT myocardial perfusion imaging in characterizing functional abnormalities thereby potentially improving test specificity [24–37]. Subsequent to echocardiography and gated SPECT imaging, CMR has now long been recognized as an accurate and reliable means of evaluating LV function. Considerable progress has been made in the field of CMR, providing accurate evaluation of LV function parameters in coronary artery disease, heart failure, hypertrophic cardiomyopathy, and many other cardiac diseases [38–49]. CMR may be more accurate than echocardiography and gated SPECT in establishing LV volumetric parameters because of its more objective analysis and superb spatial resolution, respectively [50–58]. In the current issue of the International Journal of Cardiovascular Imaging, Holloway et al. [59] nicely determined the accuracy of visual analysis of LV function in comparison with the accepted quantitative reference standard CMR. Cine CMR imaging was performed at 1.5 T on 44 patients with a range of LV ejection fractions (EF) between 5 and 80%. Eighteen clinicians were asked to visually assess LVEF after sequentially being shown cine images of a four-chamber (horizontal long axis), two-chamber (vertical long axis) and a short axis stack. The authors found strong correlations between visual and quantitative assessment. However, LVEF was underestimated in all categories (by 8.4% for horizontal long axis, 8.4% for horizontal long axis + vertical long axis and 7.9% for horizontal long axis + vertical long axis + short axis stack). LVEF was particularly underestimated in patients with mild LV dysfunction (17.4%, P < 0.01), less for moderate (4.9%) and not for severe impairment (1%). It was concluded that assessing more than one view of the heart improved visual assessment of LVEF. However, the 18 clinicians underestimated LVEF by 8.4% on average, with particular inaccuracy for those patients with mild LV dysfunction. Given the important clinical information provided by LV assessment, in particular in deformed left ventricles, the authors recommended quantitative analysis for accurate assessment of LV function. Several studies have compared visual and quantitative assessment of LVEF, both in normal subjects and patients with impaired LV function [60–68]. Nearly all studies showed that LVEF is underestimated by visual estimation compared with the quantitative assessment. Holman et al. [65], using a dedicated analytical software package (MASS version 1.0) including a modified centerline method and a new 3D-analysis approach, showed in 25 patients after acute myocardial infarction that the use of three-dimensional quantitative analysis of cine CMR images accurately quantifies the extent of regional LV dysfunction in the infarcted heart. Van der Geest et al. [66] evaluated a computer algorithm for the automated detection of LV endocardial and epicardial boundaries in time series of short-axis CMR images based on an Active Appearance Motion Mode. In 20 short-axis CMR examinations, manual contours were defined in multiple temporal frames (from end-diastole to end-systole) in multiple slices from base to apex. Global LV function results derived from automatically detected contours were compared with results obtained from manually traced boundaries. Automated contour detection resulted in small, but statistically non-significant, underestimations of LV volumes and mass: and an excellent agreement was observed in the LVEF. The fully automated contour detection method provided assessment of quantitative global LV function that is comparable to manual analysis, but offered the advantage of being more consistent, more reproducible, and less operator-dependent. Sievers et al. [67] investigated 100 subjects (40 normal subjects, 40 patients with ischemic cardiomyopathy, and 20 patients with nonischemic cardiomyopathy) using a 1.5-T CMR imager. LVEF was significantly underestimated by the visual reader in all 3 groups. The difference was larger in normal subjects than in patients with cardiomyopathy. The interobserver variability was smaller for the quantitative assessment than for the visual estimation. Attili et al. [69] reported that recent quantitation-oriented advances in CMR hardware and software have resulted in significant improvements in image quality and a reduction in imaging time. To conclude, the study by Holloway et al. [59] confirms that the visual CMR approach for LVEF assessment may be used for rapid assessment of LV function in clinical practice where accuracy is of less concern. For an accurate analysis of LV function, the quantitative standard short axis approach is required.

Short- vs long-axis approach to ultrasound-guided peripheral intravenous access: a prospective randomized study

Objective The objective of the study was to determine if the short-axis approach and long-axis approach to ultrasound-guided peripheral intravenous access (USGPIV) differ in success rate, catheter insertion time, and number of needle sticks. Methods A convenience sample of emergency department patients aged 18 to 65 years with difficult IV access (2 or more failed landmark attempts) was prospectively randomized to short-axis or long-axis USGPIV. Time from skin puncture to catheter insertion (insertion time) and number of needle sticks were recorded. Number of needle sticks and insertion time were compared using Mann-Whitney U tests. Results Forty subjects were enrolled; 20 were randomized to the short-axis and 20 to the long-axis approach. Success rate was 95% (19/20; 95% confidence interval, 85%-100%) in the short-axis group compared with 85% (17/20; 95% confidence interval, 69%-100%) in the long-axis group. All 3 subjects with failed IV placement in the long-axis group had successful rescue USGPIV placement in short axis. Median insertion time was 34 seconds (interquartile range, 35 seconds) for the short-axis group compared with 91 seconds (interquartile range, 59 seconds) for the long-axis group ( P = .02). Mean number of needle sticks was 1.5 (±SD 0.7) in the short-axis group compared with 1.4 (±SD 0.7) in the long-axis group ( P = .82). Conclusions Short-axis USGPIV technique required less insertion time than the long-axis technique. Success rate was higher in the short-axis group, but this difference was not statistically significant. However, all of the failed IVs in the long axis were rescued successfully in short axis.

Needle tip visualization during ultrasound-guided vascular access: short-axis vs long-axis approach

Objectives Ultrasound guidance for central venous catheterization improves success rates and decreases complications when compared to the landmark technique. Prior research has demonstrated that arterial and/or posterior vein wall puncture still occurs despite real-time ultrasound guidance. The inability to maintain visualization of the needle tip may contribute to these complications. This study aims to identify whether long-axis or short-axis approaches to ultrasound-guided vascular access afford improved visibility of the needle tip. Methods A prospective trial was conducted at a level I trauma center with an emergency medicine residency. Medical students and residents placed needles into vascular access tissue phantoms using long-axis and short-axis approaches. Ultrasound images obtained at the time of vessel puncture were then reviewed. Primary outcome measures were visibility of the needle tip at the time of puncture and total time to successful puncture of the vessel. Results All subjects were able to successfully obtain simulated blood from the tissue phantom. Mean time to puncture was 14.8 seconds in the long-axis group and 12.4 seconds in the short-axis group ( P = .48). Needle tip visibility at the time of vessel puncture was higher in the long-axis group (24/39, 62%) as opposed to the short-axis group (9/39, 23%) ( P = .01). Conclusions In a simulated vascular access model, the long-axis approach to ultrasound-guided vascular access was associated with improved visibility of the needle tip during vessel puncture. This approach may help decrease complications associated with ultrasound-guided central venous catheterization and should be prospectively evaluated in future studies.

Video Analysis of Accidental Arterial Cannulation With Dynamic Ultrasound Guidance for Central Venous Access

Accidental arterial cannulation during ultrasound-guided central venous cannulation is rarely reported and should be much less likely with dynamic guidance. Although accidental arterial penetration with the needle may occur periodically without notice and with little harm, actual arterial dilation and line placement may result in serious complications. This series reports 6 such cases of accidental arterial cannulation and central line insertion under dynamic ultrasound guidance. Two of the arterial cannulations resulted in airway loss, with 1 of these ending in death. The remaining 4 arterial lines led to serious local complications. Ultrasound video analysis of each line placement or postplacement analysis was reviewed, and common pitfalls were extracted. In 3 cases, a central line went directly through the internal jugular vein (IJ) and into the carotid artery. In 1 case, a cordis introducer sheath traveled through the posterior wall of the common femoral vein and into the deep femoral artery branch below. Each patient was hypotensive and hypoxic, making traditional safety checkpoints such as aspiration of bright red blood and pulsatile flow from the syringe hub less reliable in identifying accidental arterial cannulation. All ultrasound-guided cannulations were performed by a standard short-axis approach with high-resolution linear array ultrasound transducers on modern equipment. The short-axis approach, as seen in this series, can provide a false sense of security to the practitioner and allows for potentially dangerous accidental arterial cannulation. In the setting of critically ill patients, it may be prudent to not only visualize the entire path of the needle with the long-axis approach but also confirm correct cannulation by tracing the guide wire in the long axis before line placement.

An unseen danger: Frequency of posterior vessel wall penetration by needles during attempts to place internal jugular vein central catheters using ultrasound guidance*

To evaluate the frequency of unsuspected posterior vessel wall penetration of the internal jugular vein during ultrasound-guided needle cannulation. Prospective, single-blinded observational study. Urban level I emergency department with an annual census of 80,000. Residents who had previously completed a 2-day ultrasound course including a 3-hr didactic and hands-on session on ultrasound-guided central venous cannulation. Residents were asked to place an ultrasound-guided catheter on a human torso mannequin. Residents used a short-axis approach for ultrasound guidance. During the procedure, an 8-4 MHz convex (endocavity) transducer was used to observe the path of the resident's needle without interference with the placement procedure. Unknown to residents, researchers tracked the frequency of posterior wall penetration and the final needle location when the resident felt that optimal needle placement was achieved in the lumen of the internal jugular. Residents were also asked to rate their confidence regarding appropriate final needle position on a 10-point Likert scale. Statistical analysis consisted of descriptive statistics and Spearman correlation analysis. A total of 25 residents participated. All had placed at least one ultrasound-guided central catheter previously. The median number of previous ultrasound-guided cannulations was 8.0. Sixteen (64%) residents accidentally penetrated the posterior wall of the internal jugular vein during cannulation. The median number of posterior wall penetrations was 1.0 for all residents. In six cases the final location of the needle was through the posterior wall and deep to the venous lumen. In five of these cases the carotid artery was actually mistakenly penetrated. Median confidence by residents regarding appropriate needle placement was 8.0 out of 10. More training and more ultrasound-guided catheters placed were associated with fewer posterior wall penetrations (p = .04). In this study, residents accidentally penetrated the posterior vessel wall of the internal jugular in a lifelike vascular access mannequin in the majority of cases. These results suggest that care must be taken even with ultrasound-guided central catheter placement and that alternative ultrasound guidance techniques, such as visualization of the vein and needle in longitudinal axis, should be considered.

The Oblique View: An Alternative Approach for Ultrasound-Guided Central Line Placement

Abstract Background: Numerous studies have shown significant benefits of using real-time ultrasonography for central line intravenous access. Traditionally, the ultrasound probe is placed along the short axis of the vein to visualize and direct needle placement. This view has some limitations, particularly being able to visualize the needle tip. Some practitioners place the ultrasound probe in the long axis of the vessel to direct needle placement, allowing better visualization of the needle entering the vein, but this does not allow visualization of relevant anatomic structures. Objectives: We describe an alternative means to obtain ultrasound-guided vascular access using an oblique axis rather than the traditional short-axis approach. Discussion: This view allows better visualization of the needle shaft and tip but also offers the safety of being able to visualize all relevant anatomically significant structures at the same time and in the same plane. This orientation is halfway between the short and long axis of the vessel, allowing visualization of the needle as it enters the vessel. This capitalizes on the strengths of the long axis while optimizing short-axis visualization of important structures during intravenous line placement. Conclusion: Ultrasound-guided vascular access can be obtained in a variety of ways. We describe a technique that is used by some experienced ultrasound users but that has never been fully described in the literature. This technique for obtaining ultrasound-guided vascular access offers another option for attempting ultrasound-guided vascular access that has the potential to improve success rates and minimize complications associated with intravenous access.

Ultrasound-Guided Internal Jugular Venipuncture by Short-Axis Approach in 203 Cases at the University of the Ryukyus Hospital

血管の短軸像を基に超音波ガイド下に内頸静脈穿刺を行った. その有効性や合併症を調べるため, 過去の記録を基に検討した. 穿刺法のマニュアルを基に学習, シミュレータで練習してから, 臨床に臨んだ. 穿刺は, 医師1～3年目 (18人) が行い, 穿刺困難例では指導医師が代わった. 患者数は203人, 年齢64±13歳, 身長158±9cm, 体重58±11kgで, 初回穿刺成功率は91%, 平均穿刺回数1.1±0.5回, 総穿刺成功率は99%であった. 動脈誤穿刺が2症例に発生 (1%) し, 外科的に修復した. 適切な学習と訓練により高い穿刺成功率を得たが, 動脈誤穿刺は避け得なかった. 今後の課題は合併症回避のための訓練法にある.

Visual estimation versus quantitative assessment of left ventricular ejection fraction: A comparison by cardiovascular magnetic resonance imaging

The aim of this study was to compare the visual and quantitative assessment for left ventricular ejection fraction (LVEF) in normal subjects and patients with impaired LV function. One hundred subjects (40 normal subjects, 40 patients with ischemic cardiomyopathy, and 20 patients with nonischemic cardiomyopathy) were investigated using a 1.5-T cardiovascular magnetic resonance imager. Images were acquired by a fast gradient-echo sequence with steady-state free precession using the standard short-axis method. Left ventricular EF was calculated from the sums of the outlined areas using the Simpson rule. Interobserver variability between the calculated and the visual EF was assessed. Analyses were performed randomly and blinded by 2 independent observers. Left ventricular EF was significantly underestimated by the visual read in all 3 groups (mean difference: normal subjects -2.6% +/- 2.6%, ischemic cardiomyopathy -1.7% +/- 2.1%, and nonischemic cardiomyopathy -1.2% +/- 2.1%; P < or = .02). The difference was larger in normal subjects than in patients with cardiomyopathy (P = .04). The interobserver variability was smaller for the quantitative assessment than for the visual estimation. Left ventricular EF is underestimated by visual estimation compared with the quantitative assessment. The visual approach for EF assessment may be used for rapid assessment of left ventricular function in clinical practice where accuracy is of less concern. For most accurate analysis, the quantitative standard short axis approach is required.

Assessment of Regional Left Ventricular Function: Accuracy and Reproducibility of Positioning Standard Short-Axis Sections in Cardiac MR Imaging

The assessment of regional left ventricular (LV) function with cardiac magnetic resonance (MR) cine techniques requires a standardized section positioning. A simple selective short-axis method for selective positioning of three short-axis sections (basal, midcavity, apical) was tested for its accuracy, compared with accepted criteria, in 21 volunteers (mean age, 32 years +/- 11) and in 23 patients with myocardial infarction (mean age, 56 years +/- 12). Reproducibility of section positioning and of regional LV parameters was tested in the volunteers. Among the six accuracy criteria defined for standard sections, the selective short-axis approach had an average accuracy of 90.9% in volunteers and 87.7% in patients, compared with 92.1% and 90.6%, respectively, for a multisection approach covering the whole LV. There was very good reproducibility of the selected intersection gap (r = 0.89, P < .001) and of measured midcavity end-diastolic diameters in vertical (r = 0.83, P < .001) and horizontal (r = 0.85, P < .001) long-axis orientations. The proposed method produces standardized short-axis section positions that meet the recommendations for cardiac imaging. The study was approved by the local ethics committee, and all subjects gave written informed consent.

The Use of Anatomic M‐Mode Echocardiography to Determine the Left Atrial Appendage Functions in Patients with Sinus Rhythm

Left atrial appendage (LAA) contractile dysfunction is associated with thrombus formation and systemic embolism. LAA function is determined by its flow velocities and fractional area change. This study was performed in order to determine the LAA functions with the anatomic M-mode echocardiography (AMME). Our study comprised 74 patients who had sinus rhythm and underwent transesophageal echocardiography (TEE) for various reasons. LAA fractional change (LAAFAC) was measured by manual planimetry in a transverse basal short-axis approach and LAA emptying and filling velocities also were measured. The AMME values were determined by an M-mode cross section from a cursor placed beneath the orifice of the LAA in transverse basal short-axis imaging. From these values LAA fractional shortening (LAAFS) and ejection fraction (LAAEF) were calculated. LAAEF was calculated by the Teicholz method. The comparisons were conducted, and no correlations between the LAA late filling and the anatomic M-mode values were found (for LAAFS r = 0.18; P > 0.05 and for LAAEF r = 0.19; P > 0.05). There were significant but poor correlations among the LAA late emptying with the anatomic M-mode measurements (for LAAFS r = 0.26; P < 0.05 and for LAAEF r = 0.30; P < 0.01), whereas, there were significant and good correlations between the LAAFAC and the anatomic M-mode values (for LAAFS r = 0.75; P < 0.01 and for LAAEF r = 0.78; P < 0.01). There were significant differences between the valvular heart disease group and the normal group, and between the valvular heart disease group and the ASD group (for LAAFAC P < 0.01, for LAAEF P < 0.01, for LAAFS P < 0.01). There was no difference between the normal group and the ASD group. Our study showed that the LAAEF and LAAFS in patients with sinus rhythm obtained via anatomical M-mode echocardiography is a new method, which can be used instead of left atrial appendage area change.

Assessment of Left Atrial Volumes in Sinus Rhythm and Atrial Fibrillation Using the Biplane Area?Length Method and Cardiovascular Magnetic Resonance Imaging with TrueFISP

To determine whether the biplane area-length method can be used for the evaluation of left atrial volumes and ejection fraction with cardiovascular magnetic resonance imaging (CMR) by TrueFISP in normal subjects and patients with atrial fibrillation. Atrial fibrillation is the most common arrhythmia in elderly patients. Left atrial size and volumes play an important role in predicting short and long-term success after cardioversion. Fifteen healthy subjects (mean age 65.6+/-6.4 years) and 18 patients (mean age 67.2+/-8.8 years) with atrial fibrillation were examined by CMR (Magnetom, Siemens, Erlangen, Germany). Images were acquired by TrueFISP using the horizontal and vertical long-axis plane to measure left atrial end-diastolic and end-systolic areas and longitudinal dimensions. Volumes were determined with commercially available software. Left atrial end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), and ejection fraction (EF) were determined by the biplane area-length method and compared to findings obtained by the standard short-axis method. Images were acquired and analyzed a second time in the patients with atrial fibrillation. There was no difference in age between men and women (p=0.147) and healthy subjects and patients (p=0.128) included in the study. EDV and ESV were significantly higher and SV and EF significantly lower in patients with atrial fibrillation than in healthy subjects (p < or = 0.009), regardless of the method used. The values obtained for EDV and ESV by the biplane area-length method were significantly higher in both healthy subjects (p<0.001) and patients with atrial fibrillation (p<0.001) than those obtained by the standard short-axis approach, whereas SV (p> or = 0.057) and EF (p> or = 0.118) did not differ significantly. In the second investigation in patients with atrial fibrillation, ESV, SV, and EF did not differ significantly between the two methods (p> or =0.481). Assessment of interobserver variability revealed good agreement in the findings of the two observers, both in normal sinus rhythm and atrial fibrillation (overall variability 0.8+/-6.5%). The biplane area-length method can be used in CMR images obtained by TrueFISP to assess left atrial volumes and ejection fraction in normal subjects and patients with varying cardiac cycle length, as in atrial fibrillation.

Short‐axis versus Long‐axis Approaches for Teaching Ultrasound‐guided Vascular Access on a New Inanimate Model

Objectives: To determine whether a short‐axis (SA) or long‐axis (LA) ultrasound (US) approach to guidance for line placement results in faster vascular access for novice US users. Also, to assess if there was a difference in the number of skin penetrations and needle redirections between the two guidance techniques. Methods: This was a prospective, randomized, observational study of emergency medicine (EM) residents at a Level I trauma center. A gelatin dessert and dietary fiber supplement mixture, providing a realistic US image, were placed inside a synthetic arm skin that is used for training phlebotomists and contains a rubber vein filled with red fluid at a depth of 1.5 cm. After a 30‐minute tutorial on US‐guided vascular access, EM residents were randomized to one of two groups. Group one attempted SA first and then the LA. Group two tried LA first followed by the SA. Time from skin break to vein cannulation, number of skin breaks and needle redirections, and difficulty of access on a 10‐point Likert scale as reported by residents were recorded. Statistical analysis included paired Student's t‐test with 95% confidence intervals (95% CIs). Results: Seventeen EM residents participated. The mean times to vein cannulation in SA and LA were 2.36 minutes (95% CI = 1.15 to 3.58) and 5.02 minutes (95% CI = 2.90 to 7.13), respectively (p = 0.03). The mean numbers of skin breaks for SA and LA were 4.18 (95% CI = 1.18 to 7.17) and 5.76 (95% CI = 1.83 to 9.69), respectively (p = 0.49). The mean numbers of needle redirections in the SA and LA were 13.71 (95% CI = 4.51 to 22.89) and 18.17 (95% CI = 7.95 to 28.40), respectively (p = 0.51). The mean difficulty scores for SA and LA were 3.99 (95% CI = 2.42 to 5.67) and 5.86 (95% CI = 4.32 to 7.40), respectively (p = 0.17). Conclusions: Novice US users obtain vascular access faster with an SA approach on an inanimate model.

Short Axis versus Long Axis Approaches for Teaching Ultrasound Guided Vascular Access

Short Axis versus Long Axis Approaches for Teaching Ultrasound Guided Vascular Access

Quantification of ultrasonic anisotropy in normal myocardium with lateral gain compensation of two-dimensional integrated backscatter images

Anisotropy of ultrasonic scattering and attenuation in heart tissue depends on the specific orientation of myofibers with respect to angle of insonification. We used lateral gain compensation (LGC) to correct two-dimensional cardiac images for physiologic anisotropy. Normal hearts excised from three dogs and five pigs were insonified in a water tank with both 2.5 and 5.0 MHz phased-array transducers. Integrated backscatter was measured from a short-axis approach in the anterior wall perpendicular to the principal fiber axis, and in the septum parallel to the fiber axis. The gain in a vertical sector encompassing the septum was adjusted to compensate the image for anisotropy by matching the intensity of scattering from septal and anterior regions. The average gain required to compensate the septum for anisotropy was 16 dB at 2.5 MHz, and 20 dB at 5.0 MHz. Five healthy volunteers underwent imaging with a 2.5 MHz transducer from a parasternal short-axis view. The LGC required in vivo was approximately 16 dB at 2.5 MHz and was equivalent to that required for correction of septal anisotropy in excised hearts. Thus, normal myocardium exhibits substantial ultrasonic anisotropy that can be quantified and compensated for with clinically applicable tissue characterization techniques.

Comparison of left ventricular ejection fraction by magnetic resonance imaging and radionuclide ventriculography in idiopathic dilated cardiomyopathy

To assess the validity of gated magnetic resonance imaging (MRI) in determining left ventricular (LV) ejection fraction (EF), MRI (Spin Echo, multislicemultiphase technique on the short-axis plane) was compared with equilibrium radionuclide ventriculography in 32 patients with idiopathic dilated Cardiomyopathy. All patients underwent MRI and radionuclide ventriculography, performed consecutively on the same day (mean time interval between the 2 examinations: 40 minutes). Comparison with LVEF showed a high correlation (y = 0.79 × +3.51, r = 0.91; p < 0.001). Mean difference between radionuclide ventriculography and MRI data was 1.7, with the 95% confidence interval 0.71 to 2.68: MRI slightly underestimated LVEF. MRI interobserver and intrapatient variability (assessed in 15 of 32 patients) showed a high correlation (r = 0.91, r = 0.98). In conclusion, data suggest that MRI, using the short-axis approach and the multislice-multiphase technique, is an accurate, noninvasive, highly reproducible method of evaluating LVEF in patients with idiopathic dilated Cardiomyopathy.

Parastemal cross-sectional echocardiographic determination of aortic arch situs: A new approach

Determination of the situs of the aortic arch is extremely important in the complete evaluation of infants with congenital heart disease, as well as in infants with esophageal atresia and tracheoesophageal fistula in whom the thoracotomy incision is performed contralateral to the aortic arch. 1 Definitive determination of the side of the aortic arch can be made angiographically, but this is invasive and requires transport of the infant. The thoracic roentgenogram is not always reliable in determining aortic arch situs, particularly in newborns. Computed tomography of the thorax has also been used, 2 but tomographs are not portable. Evaluation of the aortic arch from the suprasternal notch using cardiac ultrasound has been reported. 3–6 In most studies, the sector orientation required for a long-axis image of the arch was used to distinguish situs. 3–5 The position of the descending thoracic aorta also has been used to infer the side of the aortic arch. 4–5 These techniques are subjective and depend on the skill of the operator. They do not provide for a descending aorta contralateral to the aortic arch with retroesophageal segment, nor for cardiac malpositions. The relative positions of the esophagus and aortic arch have also been used to identify the side of the arch, 6 but this technique is not useful with esophageal atresia. We therefore devised a new technique to evaluate aortic arch situs from a parasternal short-axis approach.

Echocardiographic detection of coronary artery disease: Detection of effects of ischemia on regional myocardial wall motion and visualization of left main coronary artery disease

M mode and cross-sectional echocardiographic studies at rest have been used to detect regional left ventricular wall motion abnormalities as a sign of hemodynamically significant coronary artery disease. These techniques have proved to be fairly specific but not highly sensitive. Detection of new regional wall motion abnormalities with cross-sectional echocardiography during exercise appeared practical in 80 percent of patients in preliminary studies; the finding of such abnormalities is highly specific for the presence of coronary artery disease and, with this approach, the sensitivity of echocardiography is improved. Thus, patients with anatomically severe coronary artery disease on angiography may not manifest an echocardiographic abnormality in regional wall motion even during exercise. The direct noninvasive detection of the left main coronary artery in up to 90 percent of patients studied with cross-sectional echocardiography using the short axis or apical approach, or both, has been well defined. A high sensitivity and specificity of detecting anatomically severe left main coronary artery disease using the criteria of both luminal impingement and the presence of high intensity echoes have been confirmed. Further advances in imaging techniques may allow for better definition of the coronary arterial treë.