Wave Morphology Research Articles

Reversible QRS fragmentation in Takotsubo cardiomyopathy.

An 80-year-old lady with a history of diabetes mellitus presented to the emergency room with palpitations. Electrocardiogram revealed ST-segment elevation over the inferior and lateral leads. Notably, the QRS complexes across precordial leads V4-6 and aVR were fragmented. A positive deflection was seen in lead V1, embedded within the QRS complex, which is resemblant to the Epsilon wave morphology (Figure 1, left columns). Despite such findings and raised serum troponin, she was free from chest pain. Transthoracic echocardiography showed left ventricular (LV) apical ballooning with severe hypokinesis, corroborated by invasive left ventriculography. Coronary angiography revealed no occlusive lesion. The diagnosis was Takotsubo cardiomyopathy (TTC). (Figure 2). The finding of fragmented QRS in TTC is of electrophysiological interest. Arrhythmic manifestations complicating TTC affects up to one-quarter of patients, and half is life-threatening (13.5%).1 Symptomatic atrioventricular block and less commonly sinus nodal dysfunction may mandate cardiac pacing and are due to a secondary increase in vagal tone in sympathetic overdrive. The origin of ventricular tachycardia (VT)/ fibrillation remained controversial in TTC. While QT prolongation is well-recognized in TTC that provided a substrate for polymorphic VT, the origin of monomorphic VT was believed to be catecholaminergic or automatic, and unlikely reentrant based on classical lack of myocardial fibrosis detectable as late gadolinium MRI enhancement in TCC.2, 3 However, latest research provided revoking evidence by identifying diffuse fibrosis/ micronecrosis through T1-mapping in TTC.4 QRS fragmentation, a marker of myocardial fibrosis, is predictive of sudden cardiac death in patients with ischemic and non-ischemic cardiomyopathy. Its presence in the inferior leads, in particular, was identified as an ominous sign in patients with known cardiomyopathy for subsequent sudden death,5 while lateral lead predominance conferred excess risks in subjects without structural heart disease. Whether fragmented QRS has a prognostic role in Takotsubo cardiomyopathy remained unclear. Furthermore, myocardial edema during a hyperacute phase in TTC may predispose to transient electrical inhomogeneity.2 On the contrary, the Epilson wave, an electrocardiographic finding characteristic of arrhythmogenic right ventricular cardiomyopathy, together with QRS fragmentation are both indicators of delayed ventricular depolarization. While the Epilson wave has been reported in myocarditis, how it is related to myocardial edema in the hyperacute phase of TTC and whether it may have a prognostic role remained obscure. In our patient, no significant nodal dysfunction or ventricular tachyarrhythmia occurred. She was treated with aspirin (80 mg daily), lisinopril (2.5 mg daily), bisoprolol fumarate (1.25 mg daily), and atorvastatin (20 mg daily). Three months later, reassessment echocardiography showed recovered LV systolic function with an ejection fraction of 65%, and resolution of apical ballooning. These were accompanied by a complete reversal of QRS fragmentation and the disappearance of the Epsilon wave-like morphology (Figure 1, rights columns). Ambulatory Holter assessment showed nil evidence of electrical instability. This succinct Spotlight thus re-capitulates the fundamental electro-pathophysiological basis implicated in the natural course of TTC, in which further research is needed. Li Shu Fan Medical Fellowship for Internal Medicine 2021/22 (Y.H.C.) None declared.

Continuous EEG monitoring detects nonconvulsive seizure and Ictal-Interictal Continuum abnormalities in moderate to severe ICANS following systemic CAR-T therapy.

Immune Cell Effector Associated Neurotoxicity Syndrome (ICANS) is common amongst patients receiving CD19 targeted Chimeric Antigen Receptor T-cell (CAR-T) therapy. The purpose of this study is to characterize the incidence of seizures and ictal-interictal continuum (IIC) abnormalities in patients with ICANS. Retrospective review of consecutive patients treated with axicabtagene ciloleucel (axi-cel) for recurrent high-grade systemic lymphoma at Stanford Medical Center between 2/2016-6/2019. Electronic medical records (EMR) were reviewed for clinical features, treatment information, EEG data, CRS (cytokine release syndrome)/ICANS severity, and clinical outcomes. Fifty-six patients met inclusion criteria. 85.7% of patients developed CRS, and 58.9% developed ICANS. Twenty-eight patients had EEG monitoring, of whom 26 had ICANS. Median duration of EEG monitoring was 30 hours (range .5-126 hours). Four patients (7.1%) had seizures (1 patient had a clinical generalized seizure, 2 patients had clinical and nonconvulsive seizures, and 1 patient had an isolated non-convulsive seizure). Ictal-interictal continuum abnormalities were common, of which generalized periodic discharges (GPDs) with triphasic morphology and GPDs with epileptiform morphology were most frequently seen. Generalized periodic discharges with triphasic wave morphology were found across Grade 2-3 peak ICANS severity, however the majority (86%) of patients with epileptiform GPDs had Grade 3 peak ICANS severity. Among patients receiving axi-cel, seizure occurred in 7.1% of the total cohort, representing 12% of patients with ICANS. Ictal-interictal continuum abnormalities are also seen in patients with ICANS, most commonly GPDs. 75% of patients with seizures had nonconvulsive seizures supporting the use of continuous video EEG monitoring in this population.

Influence of surface roughness on nanosecond laser-induced shock wave enhancement effects.

In this paper, an effective method is proposed for improving the energy of the shock waves that are generated by plasma expanding outward and colliding with another gas. Silicon targets are used as the response medium with roughness of 2.3 nm, 457.8 nm, 1.1 µm, and 37.1 µm, respectively. A 532-nm-laser with a pulse duration of 8 ns and a repetition rate of 10 Hz is used as the irradiation source. An intensified charge-coupled device (ICCD) is used to photograph the morphology of the shock waves. The time-resolved emission images of silicon plasma plumes are observed between 20-200 ns. As the surface roughness of the target increases, the intensity of the shock wave gradually increases, and the energy of the shock wave reaches up to 39.45 mJ at a roughness of 37.1 µm.

Gravity Wave Morphology During the 2018 Sudden Stratospheric Warming Simulated by a Whole Neutral Atmosphere General Circulation Model

AbstractAtmospheric gravity waves (GWs) during the February 2018 sudden stratospheric warming (SSW) event are simulated using the T639L340 whole neutral atmosphere general circulation model. Their characteristic morphology around the drastically evolving polar vortex is revealed by three‐dimensional (3D) visualization and ray‐tracing analyses. The 3D morphology of simulated GWs is described for the three key days that represent the pre‐SSW conditions, the mature stage for the vortex splitting, and the late SSW. The combination of strong winds along the polar vortex edge and underneath the tropospheric winds with similar wind directions consist of the deep waveguide for the upward‐propagating GWs, forming GW hot spots in the middle atmosphere. The GW hot spots associated with the development of the SSW are limited to North America and Greenland, and they include the typical upward‐propagating orographic GWs with relatively long vertical wavelengths. Different types of characteristic GW signatures are also recognized around the Canadian sub‐vortex (CV). GWs having short vertical wavelengths form near the surface and obliquely propagate over long distances along the CV winds. The non‐orographic GWs with short vertical wavelengths form in the middle stratosphere through the spontaneous adjustment of flow imbalance around the CV. Those GWs cyclonically ascend into the mesosphere along CV winds.

Calmodulinopathy is a common cause of critical cardiac phenotypes in fetus and infancy

Abstract Background Cardiac calmodulinopathy is a life-threatening arrhythmia syndrome which presents several phenotypes of inherited primary arrhythmia syndrome (IPAS), and caused by mutations in calmodulin-encoded genes (CALM1–3). We aimed clarify the frequency and their clinical characteristics of calmodulinopathy in our IPAS cohort. Methods By using next generation sequencing, we screened arrhythmia related genes including calmodulin-encoding genes in 322 unrelated symptomatic children (0–12 years) who were suspected as IPAS; they included 40 cases with lethal arrhythmic attacks (LAE) under 6-year-old. After gene screening, we investigated their physiological and clinical characteristics about mutation carriers. Results Among 322 children, we identified 6 mutations of calmodulin-encoded genes in 9 probands (2.8%); one CALM1 in 2 probands (N98S), and 5 CALM2 in 7 probands (E46K, D96V, D96G, N98S, E141K). Their clinical diagnoses were long QT syndrome (LQTS, n=4), catecholaminergic polymorphic ventricular tachycardia (CPVT, n=3) and both (n=2). Their age of diagnosis ranges at 0–9 with the median of 5 years. There were three major clinical phenotypes; 1) CALM2-D96V, and E141K: two infants with advanced atrio-ventricular block, significant QTc prolongation, severe heart failure from their fetal period – both of them deceased within 1.5-year-old. Their clinical phenotypes resembled classical Timothy syndrome caused by CACNA1C mutations. 2) CALM1-N98S (n=2), CALM2-N98S (n=2), and CALM2-D96G: four preschoolers with LAEs and one syncope: all of them were 3–5 years old. In addition, a T wave morphology of CALM2-D96G carrier was very similar to LQT1. 3) CALM2-E46K (n=2): two were first diagnosed with neurological and developmental disorders, and showed phenotype of CPVT: their cardiac phenotypes were milder compared with that of 1) or 2). Overall, these phenotypes seemed to be mutation specific (indicated in figure). Their cardiac features were severer, and the onset of LAEs was earlier compared with other genotypes of LQTS/CPVT. As the treatment, β-blocker was effective for control of LAEs. Conclusion Cardiac calmodulinopathy presented serious and potentially lethal phenotypes in fetus or infancy. To prevent cardiac death in them, we must correctly diagnose and start the treatment as earlier as possible. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): MEXT KAKENHI from the Ministry of Education, Culture, Sports, Science, and Technology of Japan

The Propagation of Coherent Waves Across Multiple Solar Magnetic Pores

Solar pores are efficient magnetic conduits for propagating magnetohydrodynamic wave energy into the outer regions of the solar atmosphere. Pore observations often contain isolated and/or unconnected structures, preventing the statistical examination of wave activity as a function of the atmospheric height. Here, using high-resolution observations acquired by the Dunn Solar Telescope, we examine photospheric and chromospheric wave signatures from a unique collection of magnetic pores originating from the same decaying sunspot. Wavelet analysis of high-cadence photospheric imaging reveals the ubiquitous presence of slow sausage-mode oscillations, coherent across all photospheric pores through comparisons of intensity and area fluctuations, producing statistically significant in-phase relationships. The universal nature of these waves allowed an investigation of whether the wave activity remained coherent as they propagate. Utilizing bisector Doppler velocity analysis of the Ca ii 8542 Å line, alongside comparisons of the modeled spectral response function, we find fine-scale 5 mHz power amplification as the waves propagate into the chromosphere. Phase angles approaching zero degrees between co-spatial line depths spanning different line depths indicate standing sausage modes following reflection against the transition region boundary. Fourier analysis of chromospheric velocities between neighboring pores reveals the annihilation of the wave coherency observed in the photosphere, with examination of the intensity and velocity signals from individual pores indicating they behave as fractured waveguides, rather than monolithic structures. Importantly, this work highlights that wave morphology with atmospheric height is highly complex, with vast differences observed at chromospheric layers, despite equivalent wave modes being introduced into similar pores in the photosphere.

Density waves in protoplanetary discs excited by eccentric planets: linear theory

ABSTRACT Spiral density waves observed in protoplanetary discs have often been used to infer the presence of embedded planets. This inference relies both on simulations as well as the linear theory of planet–disc interaction developed for planets on circular orbits to predict the morphology of the density wake. In this work, we develop and implement a linear framework for calculating the structure of the density wave in a gaseous disc driven by an eccentric planet. Our approach takes into account both the essential azimuthal and temporal periodicities of the problem, allowing us to treat any periodic perturbing potential (i.e. not only that of an eccentric planet). We test our framework by calculating the morphology of the density waves excited by an eccentric, low-mass planet embedded in a globally isothermal disc and compare our results to the recent direct numerical simulations (and heuristic wavelet analysis) of the same problem by Zhu and Zhang. We find excellent agreement with the numerical simulations, capturing all the complex eccentric features including spiral bifurcations, wave crossings, and planet-wave detachments, with improved accuracy and detail compared with the wavelet method. This illustrates the power of our linear framework in reproducing the morphology of complicated time-dependent density wakes, presenting it as a valuable tool for future studies of eccentric planet–disc interactions.

A Large-scale Virtual Patient Cohort to Study ECG Features of Interatrial Conduction Block

Abstract Interatrial conduction block refers to a disturbance in the propagation of electrical impulses in the conduction pathways between the right and the left atrium. It is a risk factor for atrial fibrillation, stroke, and premature death. Clinical diagnostic criteria comprise an increased P wave duration and biphasic P waves in lead II, III and aVF due to retrograde activation of the left atrium. Machine learning algorithms could improve the diagnosis but require a large-scale, well-controlled and balanced dataset. In silico electrocardiogram (ECG) signals, optimally obtained from a statistical shape model to cover anatomical variability, carry the potential to produce an extensive database meeting the requirements for successful machine learning application. We generated the first in silico dataset including interatrial conduction block of 9,800 simulated ECG signals based on a bi-atrial statistical shape model. Automated feature analysis was performed to evaluate P wave morphology, duration and P wave terminal force in lead V1. Increased P wave duration and P wave terminal force in lead V1 were found for models with interatrial conduction block compared to healthy models. A wide variability of P wave morphology was detected for models with interatrial conduction block. Contrary to previous assumptions, our results suggest that a biphasic P wave morphology seems to be neither necessary nor sufficient for the diagnosis of interatrial conduction block. The presented dataset is ready for a classification with machine learning algorithms and can be easily extended.

Experimental and numerical study on the explosive welding of niobium-steel

The aim of this work is to study the method of explosive welding to produce niobium-steel composite plate, which is used in nuclear industry equipment material manufacturing. The welding parameters were determined by weldability window, and numerical simulation was used to predict the wave shape of the welding interface. The morphology of the interface wave was observed by scanning electron microscope. Measured element distribution near the interface. The experimental samples were investigated using mechanical tests. The results show that the welding parameters optimized by theory and numerical simulation can be used to obtain a niobium-steel composite plate with better welding quality. It can be proved that the welding quality is better by observing the interface wave and testing the mechanical properties; it can be seen that the melting zone of the welding interface is composed of niobium and steel by the composition analysis instrument. The morphology of the welding interface wave is consistent with the numerical simulation results, and the numerical simulation shows the changes of temperature, strain, and stress during the welding process.

Post-processing refined ECG delineation based on 1D-UNet

The Electrocardiography (ECG) serves as a standard method for diagnosing cardiovascular disease due to its minimal risk, affordable price and simple application. Clinical information is embedded implicitly in the intervals, amplitude or morphology of different waves that represent the heart-beat cycle in the form of ECG signals. Manually delineating the ECG signals to locate the boundaries of the P, QRS, and T waves in each heart-beat typically requires a long time professional training. To facilitate the delineation and to increase precision, we propose a post-processing refined ECG delineation method that takes full advantage of the morphological information of a heartbeat cycle both in classifying each sample point in the ECG recording using 1D-UNet and determining the boundaries of these waveforms. To proceed, the ECG signals are split into pieces of only one heart beat cycle before sending into the 1D-UNet. These single beat-annotated ECG segments enable the network better extract the local and global features of different waveforms in the ECG, which gives rise to a very precise categorization of each sample point. The post-processing algorithm then uses the morphological information of ECG signal to get rid of the influence of the misclassified data points on the extraction of the onset/offset of different wave components. Tests carried on the two public ECG databases, i.e., the LUDB and QTDB show satisfactory delineation performance, with sensitivities 99.88% and 99.48%, respectively. These results suggest possible applications in wearable and wireless devices for health monitoring.

Map composition framework for synthetic P morphology

In this work we address the data privacy concerns and the need of extensive data sets by the deep learning models. We account the need of low computational frame work along with flexible architecture and diverse requirements. We use a novel approach to generate extensive synthetic P wave morphology sets from fifteen cycles of the real ECG record (MIT-BIH Arrhythmia dataset). Our approach is based on development of Python framework of algorithms. It consists of a composition of a variability trend of discrete realistic ECG record samples. We used regression modalities (polynomial fit and spline fit) in a novel way in R2 vector space. The space thus formed is an interspersion of real and synthetic vectors. The space indexed with each real index in the range (0–14) produced a new synthetic P morphology. We introduced a robust approach by developing threshold invariance in R peak detection. We developed R–R interval extraction and subsequently P contour extraction algorithm as part of frame-work. A similarity metric is proposed in order to compare morphologies and address the realism feel of synthetic morphology. The similarity score of generated wave is 0.72. We have observed the scope for enhancement in P contour extraction algorithm and accounting P width variability. We noted that the method used for synthetic generation is linked to the end use case application for different trade-offs. Thus there is a scope for different methods and novelty. Our method produced extensive morphologies from a fifteen cycle snapshot of the real ECG record. We also developed a GAN P wave setup to estimate the compute complexity of GAN for comparison with map composition framework. The compute complexity was found to be best case O(25K) for the Keras (P wave GAN) sequential model architecture. For map composition frame work the compute complexity is O(67K), however the compute cost is significant in case of P wave GAN which is approximately (32∗106) operations, where as for map composition the cost is approximately (0.67∗106)operations.

The Hybrid Excess and Decay (HED) model: an automated approach to characterising changes in the photoplethysmography pulse waveform

Photoplethysmography offers a widely used, convenient and non-invasive approach to monitoring basic indices of cardiovascular function, such as heart rate and blood oxygenation. Systematic analysis of the shape of the waveform generated by photoplethysmography might be useful to extract estimates of several physiological and psychological factors influencing the waveform. Here, we developed a robust and automated method for such a systematic analysis across individuals and across different physiological and psychological contexts. We describe a psychophysiologically-relevant model, the Hybrid Excess and Decay (HED) model, which characterises pulse wave morphology in terms of three underlying pressure waves and a decay function. We present the theoretical and practical basis for the model and demonstrate its performance when applied to a pharmacological dataset of 105 participants receiving intravenous administrations of the sympathomimetic drug isoproterenol (isoprenaline). We show that these parameters capture photoplethysmography data with a high degree of precision and, moreover, are sensitive to experimentally-induced changes in interoceptive arousal within individuals. We conclude by discussing the possible value in using the HED model as a complement to standard measures of photoplethysmography signals.

Noninvasive intracranial pressure in patients with traumatic brain injury

Monitoring and treatment of intracranial pressure are extremely important procedures in the management of patients with traumatic brain injury. The monitoring methods currently marketed are invasive and are not suitable for all patients. In addition to the risks offered, they are not available on all services. This study aims to describe the cases of five patients with traumatic brain injury of different severity who underwent noninvasive monitoring of intracranial pressure in the acute phase of the injury, relating the changes identified with the clinical picture presented. Patients showed important changes in intracranial pressure wave morphology, possibly related to the lesions, clinical presentation and therapeutic interventions used.

Initial and terminal T wave angle as hyperkalemia indicator in chronic kidney disease

ABSTRACT Background Hyperkalemia is one prevalent complication in chronic kidney disease and is considered fatal since it potentially causes malignant arrhythmias and mortality. It is associated with electrocardiography (ECG) changes, such as peaked T wave in all ECG leads. However, the universal definition of the peaked T wave is still unclear, with low sensitivity and specificity. Aim This study aims to determine the predictive value of initial and terminal T wave angle in detecting hyperkalemia among CKD patients. Methods A cross-sectional study was conducted at Dr. Soetomo General Hospital, including all adult hospitalized CKD patients. A caliper was used to measure T wave morphology. The initial deflection angle (Tia) and terminal deflection angle (Tta) were calculated from an arctan of T peak amplitude and the respective initial or terminal length. The receiver operating characteristics (ROC) curve was analyzed to determine the area under the curve (AUC) and optimal cutoff. Results A total of 220 CKD patients were enrolled in this study, with 98 patients with hyperkalemia (potassium >5.0). The majority of the patients were male, with a mean age of 51.12 ± 12.58 years. Ti-Tp duration, Tp-Tt duration, Tia, Tta, and Tp amplitude were significantly higher in the hyperkalemia group (all p < 0.05). A Spearman correlation analysis demonstrated a significant positive correlation of Tia (r = 0.346 and p < 0.001) and Tta (r = 0.445 and p < 0.001) with potassium levels in the participants. The optimal cutoff angle for Tta was 66.20° (sensitivity = 67.3% and specificity = 73.8%) and Tia was 61.07° (sensitivity = 66.3% and specificity = 69.7%). Conclusion The terminal T wave angle outperformed the initial angle in predicting hyperkalemia in CKD patients.

Automated localization and severity period prediction of myocardial infarction with clinical interpretability based on deep learning and knowledge graph

This paper presented an interpretable method for myocardial infarction (MI) localization and severity period prediction using 12-leads electrocardiograms (ECG) based on deep learning and knowledge graph. Firstly, the ontology structure of knowledge graph for MI intelligent diagnosis was established based upon the diagnosis logic and strategy of doctors, and ontology attributes and relationships between attributes were extracted. Then, the entity’s attribute values including the beat morphology of QRS waves, ST segments and T waves were extracted along with the method based on DenseNet network and diagnostic rules. Once again, attribute values were linked to the ontology structure of domain knowledge graph. Furthermore, production rules were employed to reason MI diagnosis results. Finally, all the related experiments were conducted and verified with a high-quality ECG database. For the severity period prediction of MI patients, the average accuracy, sensitivity, specificity and F1 value were 93.65%, 94.86%, 97.76% and 94.27%. For MI localization, the F1 value of IMI, ASMI, AMI, EAMI, LMI, APMI and HC with single period and single infarction areas were 97.56%、93.83%、79.65%、80.81%、87.18% and 70.59%, and the average F1 was 86.88%. Notedly, the overall accuracy was 100.00% for MI patients with the single period and multiple infarction areas and 95.16% for multiple periods and multiple infarction areas. These results all displayed the superiority of the proposed method compared with other deep learning methods, and the clinical interpretability with the knowledge graph of the patient was used to explain how the diagnostic results were given.

Analysis of P-wave Changes for Prediction of Atrial Fibrillation Episodes

Atrial fibrillation (AF) is the most frequent arrhythmia in clinical practice. It usually initiates as a paroxysmal activity (PxAF), with the subject having sinus rhythm, with interleaved AF episodes.&#x0D; The objective of the study is to evaluate the observations made by Pyotr Platonov, who hypothesized that slower conduction in the atria and the presence of fibrosis in the atrial myocardium, both associated to AF, lead to P waves widened, more complex and with increased rugosity.&#x0D; The study shows that P wave morphology significantly changes prior to the onset of AF episodes in PxAF, increasing the variability, making more complex P-wave loop, and enlarging the duration, which can be attributed to the de-structuring of the atrial wavefront.

A Watch-Type Electrocardiography Is a Reliable Tool for Detecting Paroxysmal Cardiac Arrhythmias.

Background: A substantial proportion of cardiac arrhythmias are paroxysmal in nature, and 12-lead electrocardiography (ECG) and Holter monitoring often fail to detect paroxysmal arrhythmias. We designed and evaluated a watch-type, electrocardiograph-recording, wearable device (w-ECG) to overcome the limitations of 12-lead ECG and Holter monitoring. Methods: We prospectively enrolled 96 patients with symptoms assumed to be related to cardiac arrhythmias. Electrocardiography recording was performed with both the w-ECG and Holter monitoring. Detection of any arrhythmia was the primary outcome endpoint and was compared between the w-ECG and Holter monitoring. Results: Any arrhythmia was detected in 51 (53.1%) and 27 (28.1%) patients by the w-ECG and Holter monitoring, respectively (odds ratio (OR) = 2.9, p < 0.001). The w-ECG was superior to Holter monitoring for the detection of clinically significant arrhythmias (excluding atrial premature contraction, ventricular premature contraction, and non-sustained atrial tachyarrhythmia) (OR = 2.34, p = 0.018). In 27 (28.1%) patients, cardiac arrhythmias were detected only by the w-ECG, with atrial fibrillation being the most frequent case (13 patients). Based on ECGs recorded by using the w-ECG, 17 patients (17.7%) received therapeutic interventions, including radiofrequency catheter ablation. Conclusions: The w-ECG is capable of recording ECGs of good quality, with a discernable P wave and distinguishable QRS morphology. The ability of the w-ECG to detect cardiac arrhythmias was significantly better than that of Holter monitoring, and a significant proportion of patients received therapeutic intervention based on ECGs recorded by the w-ECG.

Relationship between dialysis quality and brain compliance in patients with end-stage renal disease (ESRD): a cross-sectional study.

The high number of patients with end-stage kidney disease (ESRD) on hemodialysis makes it necessary to conduct studies aimed at improving their quality of life. To evaluate brain compliance, using the Brain4care method for intracranial pressure (ICP) monitoring, among patients with ESRD before and at the end of the hemodialysis session, and to correlate ICP with the dialysis quality index (Kt/V). Cross-sectional study conducted at a renal replacement therapy center in Brazil. Sixty volunteers who were undergoing hemodialysis three times a week were included in this study. Brain compliance was assessed before and after hemodialysis using the noninvasive Brain4care method and intracranial pressure wave morphology was analyzed. Among these 60 ESRD volunteers, 17 (28%) presented altered brain compliance before hemodialysis. After hemodialysis, 12 (20%) exhibited normalization of brain compliance. Moreover, 10 (83%) of the 12 patients whose post-dialysis brain compliance became normalized were seen to present good-quality dialysis, as confirmed by Kt/V > 1.2. It can be suggested that changes to cerebral compliance in individuals with ESRD occur frequently and that a good-quality hemodialysis session (Kt/V > 1.2) may be effective for normalizing the patient's cerebral compliance.

The significance of widely split P waves: a case report

BackgroundP wave morphology on electrocardiogram is often overlooked but indicates abnormal cardiac conduction from various etiologies. Split P waves on electrocardiogram have been reported previously but not in a perioperative setting.Case presentationA 69-year-old Caucasian male patient with widely split P waves on his preoperative electrocardiogram was scheduled for a reimplantation right total hip replacement under a combined spinal–general anesthetic technique. The patient was evaluated prior to surgery by a cardiologist and the preoperative anesthesia clinic without any comment on the abnormal P wave morphology on electrocardiogram. The patient was cleared to proceed with anesthesia and surgery. Following induction of general anesthesia, his cardiac rhythm changed to a Mobitz type II pattern. The surgical procedure was cancelled, and a permanent cardiac pacemaker was inserted.ConclusionsAnesthesiologists should be aware that the presence of widely split P waves on electrocardiogram indicates the presence of atrial conduction abnormalities, likely from an ischemic or infiltrative process that can lead to more serious cardiac arrhythmias. P wave morphology should be observed and noted during the perioperative period for all patients.

Attractor Reconstruction for Quantifying the Arterial Pulse Wave Morphology During Device-Guided Slow Breathing

Attractor reconstruction is a new way to quantify the morphology of a cardiovascular waveform by plotting all data points in the three-dimensional phase space, generating a trajectory of overlapping loops. The aim of this study is to show the feasibility of an automatic approach to quantify pulse wave attractors from a device-guided breathing study, and to link attractor features to pulse waveform features. The recently developed feature extraction technique is applied to arterial pulse waveform data of 30 patients with treated hypertension. The patients performed a device-guided slow breathing exercise. The generated attractors were categorized into three different shapes: triangular attractors, bent attractors and attractors with overlapping arms. The average height of the attractors continuously and progressively dropped from 41.8 [35.4, 55.1] AU to 34.5 [25.4, 47.3] AU (p < 0.001) during the breathing exercise. We have shown that the novel approach to quantify pulse wave attractors is feasible and can be used to detect changes in the morphology of arterial pulse waveforms. Device-guided slow breathing exercise has a shrinking effect on the average height of the attractors, which may indicate a reduction in blood pressure.