Accurate Assessment Of Cardiac Function Research Articles

The importance of heart rate on left ventricular global longitudinal strain in echocardiography: novel insights facilitated by automated deep learning methods

Abstract Background Heart rate (HR) is assumed to influence echocardiographic measurements. Consequently, HR needs to be considered for accurate assessment of cardiac function. Despite left ventricular global longitudinal strain (LV GLS) being recognised as a valuable measure of cardiac function, its normal reference ranges remain confined to patients within a limited range of resting HR. So far, time-consuming manual analyses and high measurement variability have precluded comprehensive assessment of the interplay between HR and LV GLS. Using fully automated GLS measurements provided by novel deep learning (DL) methods, it is now possible to evaluate changes in LV GLS across a wide range of HR. Purpose To improve echocardiographic assessments across a wide range of HR intervals, we aimed to study the influence of controlled HR variations on LV GLS using programmable pacemakers and fully automated DL measurements. Methods Participants with sinus node dysfunction and implanted programmable pacemakers were enrolled. Echocardiographic acquisitions were obtained at baseline HR and during stepwise increments by 10 beats/min, targeting a range from 50 to 140 beats/min. Recordings of cine-loops including 10 cardiac cycles were obtained for the four-chamber, two-chamber, and apical long axis view. LV GLS was measured for all cycles using a fully automated DL method developed by our group, and presented as mean of the three standard apical views for all patients at each HR level. A linear mixed model was used for construction of an overall trendline based on the estimated fixed effects across all 50 patients, stating patient number as the random effect. The correlation between HR and LV GLS was evaluated by a likelihood ratio test. Results Fifty patients were included, 52% females, mean age 68 years (27 to 88 years). All patients had preserved atrioventricular conduction. Resting HR ranged from 50 to 87 beats/min (mean 64 beats/min). At baseline echocardiographic acquisition, most participants were within normal ranges for LV volumes, systolic and diastolic function. A total of about 13,000 cardiac cycles were automatically analysed by the DL method. The overall trend demonstrated a linear relation between increasing HR and decreasing absolute LV GLS (Figure 1). Across HR increments from 50 to 140 beats/min, there was a 32% (22%–42%) reduction in absolute LV GLS, declining from -17.1% to -11.7%. The strong correlation between changes in HR and LV GLS was further supported by a highly significant likelihood ratio test (p-value <0.001). Conclusions There was a reduction of absolute LV GLS with increasing HR. These findings emphasize the importance of integrating HR considerations into clinical echocardiography practice. Moreover, the results highlight that DL methods can unlock substantially richer insights from individual patient data, offering a new pathway towards more personalized and precise cardiac diagnostics.Figure 1

Clinical Complications of Beck's Triad in Cardiac Tamponade: Implications for Management and Patient Outcomes

Cardiac tamponade is a critical medical emergency caused by fluid accumulation in the pericardial space, resulting in heart compression. Beck's triad is a key clinical indicator for diagnosing this condition. This integrative review aimed to assess the clinical complications associated with Beck's triad in cardiac tamponade and its implications for patient management and treatment. An electronic search was conducted in the PubMed and BVS (Lilacs & Medline) databases using targeted descriptors. Studies published in the last 10 years that addressed Beck's triad's clinical complications in cardiac tamponade were included, while studies that did not meet the inclusion criteria were excluded. The review identified a range of clinical complications associated with Beck's triad, such as cardiac tamponade, pericardial effusion, hemoptysis, and cardiac arrhythmias, arising from causes including congenital heart disease, viral infections, and invasive procedures. Cardiac tamponade can also lead to systemic complications, raising the risk of thromboembolic events. Management of these complications should be individualized based on the clinical presentation and underlying cause of cardiac tamponade. Echocardiography is essential for diagnosis and ongoing monitoring, allowing accurate assessment of cardiac function and pericardial fluid volume. Timely treatment, including pericardial drainage and hemodynamic support, is critical to lowering morbidity and mortality in cardiac tamponade cases. Early recognition, accurate diagnosis, and prompt management of complications related to Beck's triad are vital for optimizing outcomes. Recognizing early signs and symptoms of severe complications is essential for timely intervention and prevention of further adverse outcomes. A multidisciplinary approach, coupled with continuous education of healthcare professionals, is crucial to implementing best practices and improving patient outcomes in cardiac tamponade.

High‐Frequency 4D Ultrasound Evaluation of Temporal Changes in Endocardial Surface Strain after Myocardial Infarction

Myocardial infarction (MI) is a leading cause of death and accurate assessment of cardiac function after MI is critical for understanding mechanisms of post‐MI remodeling, recovery and treatment. Most previous studies assessed cardiac function using echocardiographic images of only one section of the heart. Newly developed high‐frequency 4D ultrasound (4DUS) may provide more accurate evaluation of cardiac function, especially after MI when geometry of the heart is abnormal. We investigated left ventricle (LV) endocardial surface peak systolic strain (SPSS) using 4DUS images (VEVO‐3100) before (baseline) and 24‐hr, 72‐hr and 1‐week post‐MI in male Sprague‐Dawley rats (n=5) subjected to left descending coronary artery ligation. Full‐length LV short‐axis ECG‐gated cine loops were acquired with ~11 µm stepwise increments. Compared to baseline, ejection fraction was significantly reduced 24‐hr, 72‐hr and 1‐week post‐MI (65±1 vs. 35±1, 34±3 and 31±2%, respectively). We also observed that SPSS showed different contractility patterns in the base, mid and apical heart regions. Among 17 myocardial segments analyzed, only septal segments were not affected by MI, with the exception of base anterior septal segment which showed reduced SPSS 72‐hr post‐MI (‐4.3 ± 2%) compared to baseline (‐26.5 ± 3%), indicating that the base is more sensitive to MI injury than mid‐LV. Since cardiac global and regional metrics are usually estimated in the mid‐LV, conventional methods may underestimate cardiac function in MI models. Thus, 4DUS with 3D‐strain analysis appears to be a valuable and sensitive tool for improved detection of cardiac disease progression.

Review of ultrasound contrast agents in current clinical practice with special focus on DEFINITY® in cardiac imaging.

Echocardiography is the most widely used noninvasive modality to evaluate the structure and function of the cardiac muscle in daily practice. However, up to 15-20% of echocardiograms are considered suboptimal. To enable accurate assessment of cardiac function and wall motion abnormality, the use of ultrasound microbubble contrast has shown substantial benefits in cases of salvaging nondiagnostic studies and enhancing the diagnostic accuracy in daily practice. DEFINITY® is a perflutren based, lipid shelled microbubble contrast agent, which is USFDA approved for left ventricular opacification. The basis of ultrasound microbubbles, its development, and the clinical role of DEFINITY(characteristics, indications and case examples, side effect profile and existing evidence) is the subject of discussion in this review.

Video-based AI for beat-to-beat assessment of cardiac function.

Accurate assessment of cardiac function is crucial for the diagnosis of cardiovascular disease1, screening for cardiotoxicity2 and decisions regarding the clinical management of patients with a critical illness3. However, human assessment of cardiac function focuses on a limited sampling of cardiac cycles and has considerable inter-observer variability despite years of training4,5. Here, to overcome this challenge, we present a video-based deeplearning algorithm-EchoNet-Dynamic-that surpasses the performance of human experts in the critical tasks of segmenting the left ventricle, estimating ejection fraction and assessing cardiomyopathy. Trained on echocardiogram videos, our model accurately segments the left ventricle with a Dice similarity coefficient of 0.92, predicts ejection fraction with a mean absolute error of 4.1% and reliably classifies heart failure with reduced ejection fraction (area under the curve of 0.97). In an external dataset from another healthcare system, EchoNet-Dynamic predicts the ejection fraction with a mean absolute error of 6.0% and classifies heart failure with reduced ejection fraction with an area under the curve of 0.96. Prospective evaluation with repeated human measurements confirms that the model has variance that is comparable to or less than that of human experts. By leveraging information across multiple cardiac cycles, our model can rapidly identify subtle changes in ejection fraction, is more reproducible than human evaluation and lays the foundation for precise diagnosis of cardiovascular disease in real time. As a resource to promote further innovation, we also make publicly available a large dataset of 10,030 annotated echocardiogram videos.

Critical Heart Failure and Shock.

The objectives of this review are to discuss the clinical assessment, pathophysiology, and management of shock, with an emphasis on circulatory physiology, cardiopulmonary interactions, and pharmacologic strategies to optimize systemic oxygen delivery. These principles will then be applied to the clinical syndromes of heart failure and cardiogenic shock that are seen in children. MEDLINE, PubMed. An understanding of essential circulatory physiology and the pathophysiology of shock are necessary for managing patients at risk for or in a state of shock. A timely and accurate assessment of cardiac function, cardiac output, and tissue oxygenation and the means by which to enhance the relationship between oxygen delivery and consumption are essential in order to optimize outcomes.

Assessment of Cardiac Function by Echocardiography.

Accurate assessment of cardiac function by transthoracic echocardiography (TTE) plays an essential role in clinical cardiology. While left ventricular ejection fraction (LVEF) assessment has traditionally been the most commonly used objective echocardiographic marker, many other echocardiographic parameters exist that permit an enhanced understanding of cardiac function. These range from 2-dimensional (2D) and 3-dimensional (3D) morphologic parameters to functional parameters such as wall strain and myocardial performance index. In this review, we survey a variety of TTE-based techniques that are utilized in practice to assess the systolic cardiac function of both the left and right ventricles.

Investigation on the feasibility of left ventricle and coronary artery angiography through femoral artery 1in rabbits

Objective To investigate the feasibility of performing left ventricle and coronary artery angiography in rabbits through femoral artery as a method to provide accurate assessment of cardiac function in heart failure and myocardial infarction. Methods A total of 20 New Zealand rabbits were used and left ventricle and coronary artery angiography was performed through femoral artery. Peak left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure (LVEDP) and left ventricular ejection fraction (LVEF) were recorded. Results Left ventricle and coronary artery angiography was successfully conducted in 12 rabbits, but failed in 5 rabbits during catheterization. The other 3 rabbits died during the procedure. The mean LVEDP was (5.08±2.01)mmHg (1 mmHg=0.133 kPa), the mean LVSP was (101.04±21.12) mmHg, and the mean LVEF (68±7)%. Conclusions Left ventricle and coronary artery angiography through femoral artery in rabbits is feasible and can be used to accurately evaluate cardiac function. The method is reliable, but has strict requirements on equipment and training. Key words: Coronary angiography; Ventricular function, left

MR Harmonic Phase surface for tracking cardiac motion

Purpose Quantitative analysis of left ventricle motion can be performed by tracking the tag surfaces motion, where the intersection of orthogonal tag surfaces resolves the 3D motion of the heart tissue. Although, previous work was done to construct tag surfaces between image slices, it was restricted to the specific tag lines and not between them. The reconstruction of the tag surfaces, based on their harmonic phase value, enables an accurate tracking of 3D motion of the cardiac tissue, which will enable an objective and accurate assessment of cardiac function.

Accurate Automatic Detection of End-Diastole From Left Ventricular Pressure Using Peak Curvature

Precise identification of end-diastole (ED), corresponding to the end of diastole and start of systole, is crucial for accurate assessment of cardiac function. The aims of this study were to develop a new algorithm based on peak curvature (kappa(p)) for detecting ED as a "corner" in left ventricular pressure (LVP) signals, and to compare this approach with "gold-standard" ED obtained by manual annotation (ED(man)) and ED calculated with previously described algorithms that use an LVP first-derivative threshold (dP/dt(0) or dP/dt(100)), the peak LVP second-derivative (d(2)P/dt(2)(p)) or ECG R-wave peak (ECG(R)). Using customized software, all algorithms were applied to data derived from 213 large animal studies spanning a wide range of animal ages (fetus to adult), heart rates, inotropic states, and loading conditions. Differences between ED(man) and each algorithm were then compared after defining an acceptance region for the ED detection based on ED(man) interobserver variability. ED detected with kappa(p) was the most accurate (p < 0.001) and least variable (p < 0.001), with 97% of measurements within the acceptance region and difference from ED(man) of (1.5 +/- 4.2) ms. By contrast, ED was often detected early with dP/dt(0) and dP/dt(100) , and late with d(2)P/dt(2)(p) and ECG(R). These results indicate that the peak curvature algorithm using LVP provides accurate and reliable detection of ED.

Ultra‐fast and accurate assessment of cardiac function in rats using accelerated MRI at 9.4 Tesla

MRI can accurately and reproducibly assess cardiac function in rodents but requires relatively long imaging times. Therefore, parallel imaging techniques using a 4-element RF-coil array and MR sequences for cardiac MRI in rats were implemented at ultra-high magnetic fields (9.4 Tesla [T]). The hypothesis that these developments would result in a major reduction in imaging time without loss of accuracy was tested on female Wistar rats under isoflurane anesthesia. High-resolution, contiguous short-axis slices (thickness 1.5 mm) were acquired covering the entire heart. Two interleaved data sets (i) with the volume coil (eight averages) and (ii) with the four-element coil array (one average) were obtained. In addition, two-, three-, and fourfold accelerated data sets were generated through postprocessing of the coil array data, followed by a TGRAPPA reconstruction, resulting in five data sets per rat (in-plane voxel size 100 x 100 microm). Using a single blinded operator, excellent agreement was obtained between volume coil (acquisition time: 88 min) and the fourfold accelerated (<3 min) data sets (e.g., LV mass 436 +/- 21 mg vs 433 +/- 19 mg; ejection fraction 74 +/- 5% vs 75 +/- 4%). This finding demonstrates that it is possible to complete a rat cine-MRI study under 3 min with low variability and without losing temporal or spatial resolution, making high throughput screening programs feasible.

Comparative Study of High-resolution Microimaging with 30-MHz Scanner for Evaluating Cardiac Function in Mice

The accurate assessment of cardiac function in mice is challenging because of their small heart size and rapid heart rate. We examined the usefulness of novel high-resolution echocardiography (HRE) with a 30-MHz transducer in evaluating cardiac function in 20 mice compared with conventional echocardiography (CE) with a 13-MHz transducer. The left ventricular (LV) regional wall motion (RWM), LV end-diastolic dimension, fractional shortening, anterior LV wall thickness, E/A, and myocardial performance index were assessed. RWM analysis was more feasible by HRE than by CE (P < .05). Interobserver agreement in RWM analysis and correlation in LV end-diastolic dimension, fractional shortening, anterior LV wall thickness, E/A, and myocardial performance index were all better with HRE than CE. HRE is superior to CE in assessing LV function in mice. HRE is potentially a useful method for accurate assessment of cardiac function in various mice models.

How to Perform an Accurate Assessment of Cardiac Function in Mice using High-Resolution Magnetic Resonance Imaging

High-resolution magnetic resonance cine imaging (cine-MRI) is a method that allows for a non-invasive assessment of left ventricular function and mass. To perform this quantitation, hearts are imaged from the base to the apex by a stack of two-dimensional images. Thus, analysis of myocardial mass and function by cine-MRI does not rely on geometric assumptions. Geometric and functional parameters, such as end-diastolic volume (EDV), end-systolic volume (ESV) or ejection fraction (EF), are obtained by subsequent image segmentation of the respective cine frames in each slice. While this technique has been well established in clinical practice, it is now rapidly becoming the reference method in experimental cardiovascular MRI for accurate quantification of cardiac parameters, thereby aiding the phenotyping of the increasing number of transgenic and surgical mouse models. However, accurate measurement of cardiac functional parameters requires the images to be acquired in short-axis orientation of the heart, which can be difficult to define, particularly in animals with diseased hearts. Furthermore, data analysis can be the source of a systematic error, mainly for myocardial mass measurement. Here, we describe a protocol that allows for a quick and reproducible approach of obtaining the relevant cardiac views for cine-MRI, and we explain how an accurate experimental image analysis can be performed.

Evaluation of left ventricular volume and mass with breath-hold cine MR imaging.

Left ventricular (LV) volumes and mass were evaluated in 10 healthy volunteers with breath-hold cine magnetic resonance (MR) imaging. The results were compared with those obtained with conventional cine MR imaging. The breath-hold studies showed no ghosting artifact, and cardiac edges were clearly identified because of the reduced blurring. Measurements of LV end-diastolic volume (LVEDV), LV end-systolic volume (LVESV), and LV mass obtained with breath-hold cine MR imaging showed close correlation with those obtained with conventional cine MR imaging (r = .98, .97, and .99, respectively). The interobserver variabilities for LVEDV, LVESV, and LV mass determined with breath-hold cine MR imaging (4.0%, 8.0%, and 3.7%, respectively) were equal to or less than those determined with conventional cine MR imaging (4.0%, 8.6%, and 5.0%, respectively). The authors conclude that breath-hold cine MR imaging is highly useful because an accurate assessment of cardiac function is obtained in less than 5 minutes.

Monitoring Cardiac Function and Intravascular Volume in Neurosurgical Patients

Evaluation of cardiac function and intravascular volume has proved essential in two broad groups of neurosurgical patients: those with cerebrovascular disease and those with intracranial hypertension. For accurate assessment of cardiac function and intravascular volume, determinations were made by a dye dilution technique. This approach was used in 68 patients, in whom 215 dye dilution measurements were made. Useful parameters of left ventricle function included cardiac output, cardiac index, stroke volume, and mixing time. Important measures for the assessment of intravascular volume were mixing volume, dispersion volume, total peripheral resistance, central venous pressure, and mean pulmonary artery wedge pressure. Cardiopulmonary monitoring by this dye dilution technique has proved useful, relatively noninvasive, rapid, and easily repeatable in a wide variety of clinical situations in which cardiac function and state of hydration require accurate assessment. By adding this dye dilution technique to the more commonly used methods for evaluating intravascular volume and cardiac function, more accurate monitoring of critically ill neurosurgical patients can be carried out.

Hemodynamic monitoring of patients undergoing abdominal aortic surgery

Cardiac decompensation is clearly the major complication of aortic reconstructive surgery that leads to morbidity. Major changes in intravascular volume, third spacing, and increased systemic vascular resistance are extremely stressful to the diseased heart. Hemodynamic monitoring is readily available to provide an accurate evaluation of myocardial sensitivity and to allow for appropriate pharmacologic manipulation to preclude cardiac catastrophe. We believe all patients undergoing abdominal aortic reconstructive surgery should receive the benefit of pulmonary artery catheterization and intraarterial monitoring. The only requirement is a staff of surgeons, anesthesiologists, and nurses capable of correct interpretation of the data and use of drug therapy based on this information. The benefits are an accurate assessment of cardiac function with the ability to modulate the patient's hemodynamic values, preventing volume shifts, hypertensive and hypotensive crises, and abnormal fluctuations in preload and afterload, and ultimately a safer perioperative course.

THE ROLE OF ECHOCARDIOGRAPHY IN THE MANAGEMENT OF PEMATRIC RENAL PATIENTS (PTS)

Accurate assessment of cardiac function (CF), fluid status and pericardial effusion (PE) in children with renal failure is often difficult. The role of echocardiography in the management of these PTS was evaluated by analyzing 112 echograms (ECHO) obtained because of cardiopericardiac enlargement (CPE) on chest x-ray, cardiac murmur not attributable to anemia, changing fluid balance or possible bacterial endocarditis (BE) in 34 PTS. 12 PTS not requiring dialysis (NO DIAL) and 22 PTS on dialysis (DIAL) were studied. The CF and cardiac size were acceptable in all of the NO DIAL PTS and required no change in their therapy. However, 19/22 DIAL PTS had CPE. By ECHO 15/19 had left ventricular volume overload (LVVO) that was not clinically apparent, 5 had PE alone and 10 had LVVO and PE. Routine dialysis, antihypertensive drugs and diet restriction resulted in improvement of the clinical and ECHO findings in only 8. The remaining 11 PTS had persistent decreased CF on ECHO, with 6 requiring intensive ultrafiltration, 5 digoxin, and 1 of the 5 closure of an A-V fistula to improve CF and PE. One DIAL PT in whom an ECHO was done to rule out BE had hypertrophic cardiomyopathy without evidence of vegetation. An ECHO in another PT with rapid deterioration revealed a large mitral valve vegetation that had developed in 30 days, identified as Candida albicans at autopsy. Hence, echocardiography provided valuable information about fluid status and CF, and significantly aided the clinician in caring for the children with renal failure.

Cardiac function determined by echocardiogram.

Echocardiographic analysis with a strip recorder gives an accurate assessment of cardiac function, easily obtainable at the bedside of the critically ill. Ejection fraction and velocity of circumferential fiber shortening (Vcf) are the two most accurate measurements of cardiac function. The diameter of the minor axis of the left ventricle is measured in systole (Ds) and diastole (Dd). Systolic volume is (Ds)-3, diastolic volume is (Dd)-3, ejection fraction is (Dd)-3-(Ds)-3 divided by (Dd)-3, Vcf is Dd-Ds divided by Dd times LVET.