Normal Waveform Research Articles

Journal round up

Journal round up

A sonographic doppler study of hepatic vein, portal vein and hepatic artery in liver cirrhosis: correlation of hepatic haemodynamics and liver dysfunction

s / Clinical Radiology 67 (2012) S1–S10 S10 Results: We present a comprehensive pictorial review of the features of PAPVD across several imaging modalities, including tips for the general radiologist. We also describe the congenital associations which, if present, should prompt a search for PAPVD. Knowledge of the above is important particularly in the diagnostically challenging patient or where precise anatomicalmappingof thepulmonaryveins is requiredprior to intervention. Conclusion: The radiologist plays an important role in diagnosing PAPVD. A knowledge of the imaging features will lead to prompt diagnosis and facilitate pre-procedural planning, contributing to a favourable patient outcome. The CT features of chronic thromboembolic pulmonary hypertension (CTEPH) Authors: Shalini Wijesuriya, Ladli Chandratreya Purpose: Chronic occlusion of pulmonary arteries by emboli can lead to a progressive elevation of pulmonary artery pressures with sequelae such as chronic thromboembolic pulmonary artery hypertension (CTEPH) and right ventricular dysfunction. Diagnosis and early recognition of CTEPH is crucial as it is potentially curablewith pulmonary thromboendarterectomy and if left untreated, is associatedwith significant morbidity andmortality. Unfortunately, patients may go undetected for years and diagnosis is made challenging by the non-specific nature of the clinical presentation. CTEPH is being increasingly recognised and as the radiologist may be the first individual to make a diagnosis of CTEPH, knowledge of the conventional and less common CT features is crucial. Methods and materials: A pictorial review of cases of chronic thromboembolic pulmonary hypertension based on experiences at our institution. Results: We present a comprehensive pictorial review of the vascular, cardiac and pulmonary parenchymal CT features of chronic thromboembolic pulmonary hypertension. Furthermore, we discuss potential pitfalls and help distinguish CTEPH from other common mimics such as acute embolism and idiopathic pulmonary hypertension. Conclusion: We hope that highlighting the key diagnostic features in CTEPH will improve confidence, notably amongst trainees, leading to fewer diagnostic delays and an improvement in overall patient outcome. A sonographic doppler study of hepatic vein, portal vein and hepatic artery in liver cirrhosis: correlation of hepatic haemodynamics and liver dysfunction Authors: Richard H. Lo, Azizah Mohamed Afif, Yanyan Wang, Denise Lau, Chin C. Ooi Purpose: To evaluate parameters involved in haemodynamics of liver vasculature in patients with cirrhosis and in normal healthy volunteers using Doppler Ultrasound. Methods and Materials: A study sample of 32 patients with Child-Pugh A (n1⁄425), B (n1⁄45), and C (n1⁄42) liver cirrhosis was compared with a control group of 26 normal health screening participants. Right hepatic vein (RHV), right portal vein (RPV) and main hepatic artery were interrogated. Results: All patients in control group showed normal triphasic waveform in RHV. In the study group, RHV blunted waveform was detected in 3 patients in Child-Pugh A, 1 in B and all patients in C category. Waveform alteration was independent of Child-Pugh score. Hepatic Artery Resistive Index (HARI) was significantly higher in study group than in control group (p<0.001). Maximum Portal Vein Velocity (MPVV) also was significantly lower in study group than in control group (p1⁄40.02). Mean Maximum Hepatic Vein Velocity (MHVV) and Maximum Hepatic Artery Velocity (MHAV) did not show significant difference between the 2 groups, with p1⁄40.16 and p1⁄40.38 respectively. Conclusion: Altered waveform of hepatic veins is suggestive of changes within a cirrhotic liver. HARI and MPVV can be useful parameters to assess liver cirrhosis. Doppler Ultrasound is a good non-invasive assessment tool for evaluating the haemodynamics of liver cirrhosis.

Comparison of visual evoked potentials between premature and full‐term childrens

AbstractPurpose To evaluate the correlation of visual evoked potential(VEP) abnormalities with prematurity, presence of brain lesion, brain lesion localization, especially visual cortex in children under five.Methods We evaluated VEP responses in children under five, and compare the responses according to prematurity, presence of brain lesion, and brain lesion localization. We divided the subjects into two groups, which the visual pathway involvement (retina, optic nerve, optic chiasm, lateral geniculate body, optic radiation, visual cortex) group, and non‐involvement group. The VEP responses were classified into 3 scores, Score 0: normal waveform and normal latency, Score 1: mildly or moderately attenuated waveform or delayed latency, Score 2: severely attenuated waveform or no response.Results Subjects were 58 children, 16 premature(25 weeks ~ 38 weeks), and 42 full‐term children. In premature children, 5 out of 16 had visual pathway involvement, and 12 out of 32 had it in full‐term children. In full‐term children, higher score was seen in visual pathway involvement group. On the other hand, in premature children, there was no significant difference of score between visual pathway involvement group and non‐involvement group.Conclusion In full‐term children, the incidence of VEP abnormality seems to be higher in case of visual pathway involvement. In premature children, the VEP abnormality is vulnerable although there is no visual pathway involvement.

Extra- and Intracranial Waveform Analysis Algorithm, Descriptions, Classifications, and Differential Diagnosis

Waveform recognition is an essential step in the interpretation of vascular ultrasound studies. Waveforms can vary widely as the result of systemic and focal hemodynamic changes in the precerebral and particularly intracranial vessels. Waveform pattern recognition can aid or refine the application of strict velocity criteria, and this review will focus on typical normal and abnormal waveforms. Algorithms for waveform analysis and interpretation of extra- and intracranial waveforms are discussed along with correlative imaging and clinical findings. Waveform descriptions and classifications based on prediction of vessel patency, systemic versus local circulatory conditions, and resistance to flow are provided for specific clinical conditions. Interpretation of waveforms rests on our ability to integrate systemic and cerebral hemodynamics across a wide spectrum of conditions. Intracranial vasculature poses unique challenges yet may yield new knowledge if our technologies are able to quantify blood flow beyond just velocities in the future.

Effect of sampling rate on target waveform reconstruction based on self-mixing interference

This paper presents a study of the reconstruction of target motion waveform based on the self-mixing interference (SMI) from the sampling rate of data acquiring card. It has been found that the ratio of sampling rate to motion frequency of target (RSF) is of importance in the sampled SMI waveform. Based on the experimental SMI waveforms and the corresponding sampling rate, a quantitative relationship between RSF and the number of peaks of SMI waveform are given, showing that the lowest RSF is 10 points for the normal waveform in every monotony interval of SMI waveform.

Thymic volume in healthy, small for gestational age and growth restricted fetuses

The aim of this study was to verify the hypothesis that a difference in thymic size exists between small for gestational age (SGA) fetuses, likely constitutional, and intrauterine growth restricted (IUGR) fetuses because of placental causes. We studied 27 SGA and 36 control fetuses. SGA was defined as fetal abdominal circumference (AC) and birthweight <10th percentile for gestational age. We defined as constitutional SGA those with normal uterine and umbilical artery Doppler flow velocity waveforms (FVW), and as IUGR those with abnormal uterine FVW. IUGR were further divided based on normal or abnormal umbilical FVW. Fetal thymic volume (TV) was acquired by three-dimensional ultrasound and reconstructed with virtual organ computer-aided analysis. To correct for the influence of fetal size on thymic dimension, TV/AC ratio was calculated. Controls presented a higher TV/AC compared with each group of SGA (p < 0.001). TV/AC was significantly lower in IUGR with abnormal umbilical FVW compared with both constitutional SGA (p = 0.01) and IUGR with normal umbilical FVW (p = 0.01). The differences in TV/AC between constitutional SGA and IUGR with abnormal umbilical FVW suggest that, in the latter, a specific 'trigger' might compromise trophoblastic invasion and thymic development; however, some kind of alteration of the immune system might occur in all SGA fetuses.

Renal transplant ultrasound: a pictorial review

Renal transplantation is considered the optimal treatment in patients with end-stage renal disease. Ultrasound is usually the first choice imaging modality for evaluating renal transplant anatomy and perfusion. It is important to be aware of how to image a renal transplant, the normal sonographic appearances and relevant pathological processes. Renal transplant ultrasound imaging includes duplex vascular evaluation and the operator must have a sound knowledge of both normal and abnormal Doppler waveforms. Complications following renal transplantation are usually assessed with ultrasound. The time frame in which complications can occur stretches from the immediate postoperative period to months or years following transplantation. A knowledge of the anticipated complications relative to that timescale helps to focus the examination. This pictorial review aims to demonstrate the appearances of the normal renal transplant as well as potential complications. These include vascular (renal vein thrombosis, renal artery stenosis, pseudoaneurysm and arteriovenous fistulae), parenchymal (acute rejection, acute tubular necrosis and malignancy) and urological (ureteric stricture and renal calculi) complications.

30 VALIDATING THE USEFULNESS OF DOPPLER STUDY OF HEPATIC VEINS IN PREDICTING ESOPHAGEAL VARICES IN CIRRHOTIC PATIENTS

Loss of normal hepatic venous triphasic wave form is a very sensitive non invasive marker for predicting the presence of large esophagial varices with reasonably high positive and negative predictive value. latelet count/splenic diameter ratio, if taken with a cut off of ≤909, can predict the presence of large esophagial varices with reasonably good accuracy. Comparing hepatic venous flow pattern to platelet count splenic diameter ratio,the formor is more strongly associated with the presence of large varices and scores over the latter in terms of negative predictive value. Both are comparable in terms of sensitivity, specificity and positive predictive value. Hepatic venous flow pattern did not have a statistically significant correlation with the incidence of UGI bleed.

The Variation of Waveform and Analysis of Composition for the Geoelectrical Field before Moderate and Strong Earthquakes in Qinghai‐Tibetan Plateau Regions

AbstractSite‐selective phenomenon exists in the normal waveforms of the geoelectrical fields of Qinghai‐Tibetan Plateau and its adjacent areas: rock structure of the sites, cracks and fissure water, tectonic activity and other factors affect the normal waveforms of the geoelectrical field; a large lake will contribute to the occurrence of TGF‐A waveforms nearby, TGF‐B waveforms will mostly occur in the areas where there are thick Quaternary sediments, and high water content and good water permeability of rocks, while the geoelectrical fields with no diurnal variations are prone to appear in the bedrock mountains where there are intense tectonic activities. Before moderate or strong earthquakes in the region, short‐term and impending anomaly of the geoelectrical field has a cluster phenomenon, in which there is a temporal synchronization or a few days' difference, while spatially it can be distributed near several faults in the region, manifested as a discrete phenomenon. This phenomenon of temporal clustering and spatial scattering is the short‐term and impending precursor characteristics of the geoelectrical field in the region. The Σ – Δ summation method is introduced to analyze the usual stability of spontaneous field through the observational data of the geoelectrical field, which indicate that before a moderate or strong earthquake, background value jumps of part of geoelectrical fields are a transformation phenomenon of spontaneous field; the concept and calculation method of TA, which is the sum of the first 10 order tidal harmonic amplitudes divided by the sum of the first 100 order harmonic amplitudes, are established to show quantitatively that the tidal effect of waveforms of TGF‐A, TGF‐B and non‐diurnal variation is successively reduced; the first order difference method of ΔE is adopted to analyze the higher frequency electromagnetic components in the minute order geoelectrical field monitoring data, usually the high‐frequency jumps show a certain degree of randomness and limitedness. By using three different methods of analysis, the features of spontaneous field, the telluric field and high‐frequency electromagnetic components are analyzed from the composition of the geoelectrical field, which provides a theoretical and methodological basis for the physical analysis of the geoelectrical field.

ECG 신호에서 단위패턴간 유사도분석을 이용한 부정맥 분류 알고리즘

Most methods for detecting PVC and APC require the measurement of accurate QRS complex, P wave and T wave. In this study, we propose new algorithm for detecting PVC and APC without using complex parameter and algorithms. Proposed algorithm have wide applicability to abnormal waveform by personal distinction and difference as well as all sorts of normal waveform on ECG. To achieve this, we separate ECG signal into each unit patterns and made a standard unit pattern by just using unit patterns which have normal R-R internal. After that, we detect PVC and APC by using similarity analysis for pattern matching between standard unit pattern and each unit patterns.

Revisiting the ionic mechanisms of early afterdepolarizations in cardiomyocytes: predominant by Ca waves or Ca currents?

Early afterdepolarizations (EADs) have been implicated in severe cardiac arrhythmias and sudden cardiac deaths. However, the mechanism(s) for EAD genesis, especially regarding the relative contribution of Ca(2+) wave (CaW) vs. L-type Ca current (I(Ca,L)), still remains controversial. In the present study, we simultaneously recorded action potentials (APs) and intracellular Ca(2+) images in isolated rabbit ventricular myocytes and systematically compared the properties of EADs in the following two pharmacological models: 1) hydrogen peroxide (H(2)O(2); 200 μM); and 2) isoproterenol (100 nM) and BayK 8644 (50 nM) (Iso + BayK). We assessed the rate dependency of EADs, the temporal relationship between EADs and corresponding CaWs, the distribution of EADs over voltage, and the effects of blockers of I(Ca,L), Na/Ca exchangers, and ryanodine receptors. The most convincing evidence came from the AP-clamp experiment, in which the cell membrane clamp was switched from current clamp to voltage clamp using a normal AP waveform without EAD; CaWs disappeared in the H(2)O(2) model, but persisted in the Iso + BayK model. We postulate that, although CaWs and reactivation of I(Ca,L) may act synergistically in either case, reactivation of I(Ca,L) plays a predominant role in EAD genesis under oxidative stress (H(2)O(2) model), while spontaneous CaWs are a predominant cause for EADs under Ca(2+) overload condition (Iso + BayK model).

Echocardiographic evaluation of aorto-iliac occlusive disease

Several studies demonstrated feasibility of visual assessment of the common femoral artery Doppler waveform, in an indirect evaluation of aorto-iliac segment stenosis. Patients with cardiac diseases referred for echocardiography often have coexistent arterial pathology. Since many of them are potential candidates for endovascular procedures, we decided to study, whether echocardiography can be useful for detection of aorto-iliac occlusive disease. We evaluated 92 patients with abdominal aortic aneurysm or peripheral artery occlusive disease, referred from the vascular surgery department for cardiac evaluation before surgery. At the end of an echocardiographic examination, evaluation of flow in the distal external iliac arteries with an echocardiographic probe was performed. The Doppler waveform was classified into normal—with early diastolic flow reversal or abnormal—without early diastolic flow reversal. Echocardiographic results were compared in a blinded fashion with reports from computed tomography angiography. Overall there were 58 iliac segments with significant (≥70%) area stenosis or occlusion and 126 iliac segments without significant disease on computed tomography angiography. Abnormal Doppler waveform was found in 56 out of 58 abnormal iliac segments—sensitivity 97%, and normal waveform was found in 106 out of 126 normal iliac segments—specificity 84%. Positive predictive value of abnormal Doppler waveform for significant iliac disease was 74%, and negative predicting value was 98%. Detection of significant stenoses in aorto-iliac segments is feasible with echocardiography. Further studies are necessary to evaluate its potential utility in a population of patients with cardiac disease referred for echocardiographic study.

Development of application and studies of volume-capnography in critical patients

Background Volume PETCO2 is a sigal-wave plot based on the expired carbon dioxide fraction,which is the standard tool for understanding carbon dioxide elimination and the dead space. Objective The basic principles and clinical significance of normal and abnormal waveform of v-PETCO2 is introduced. Content v-PETCO2 wave morphology depends on production, transport (pulmonary perfusion) and diffusion of the carbon dioxide, as well as any changes in respiratory pathophysiology, v-PETCO2 can be used to study the dynamics of CO2. This plot yields three parts: first phase is carbon dioxide free;phase Ⅱ represents the transition between gas from the airways and alveolar gas, and phase Ⅲ represents alveolar gas. The respiratory dysfunction reduces ventilation in some units more than others, causing an increased scatter of ventilation/perfusion (V/Q)ratios and thus of the range of alveolar PCO2 values. They results in increased slope of phase 3 and three dead space estimates derived from the v-capnogram, including the anatomical dead space, alveolar dead space and physiological dead space. This can differentiate a patient with a pulmonary embolism from a healthy patient or a COPD, ARDS or asthma patients. Trend v-PETCO2 is the standard tool for understanding carbon dioxide elimination and the dead space concept. Key words: PETCO2; Capnography; Volume-capnogram; Ventilation

Placental ischemia and changes in umbilical and uteroplacental arterial and venous hemodynamics

Objective: To relate Doppler velocimetry findings in fetoplacental and uteroplacental circulation to placental histomorphology. Material and methods: In 14 uncomplicated and 31 high-risk pregnancies Doppler velocimetry was performed in umbilical artery and vein, and in maternal uterine veins and arteries during the second half of gestation. Histopathology of the placentas was examined, especially for signs of ischemia and inflammation. Results: All fetuses in uncomplicated pregnancies had normal flow velocity waveforms in umbilical artery; in the high-risk group, 18 fetuses had abnormal flow (increased PI or absent/reverse end-diastolic flow). The latter group had more often high ischemic score and infarctions in the placenta than found in pregnancies with normal umbilical artery flow (p < 0.001 and p = 0.02, respectively). Similarly, the abnormal uterine artery flow pattern (uterine artery score 3–4) occurred more often with high ischemic score and placenta infarctions (p < 0.001 and p < 0.001, respectively). No significant associations were found between the uterine venous flow type and placental ischemia. Conclusion: Placental ischemic morphological changes were associated with Doppler ultrasound signs of increased resistance to arterial blood flow, both on the fetal and maternal sides of the placenta. No significant relation to the uterine venous flow velocities was found.

Isolated mesopic rod and cone electroretinograms realized with a four-primary method

The purpose of this study was to evaluate the feasibility of measuring rod and cone electroretinograms (ERGs) at a single mesopic adaptation level. To accomplish this, a four-primary photostimulator was implemented using a commercially available ERG system (Diagnosys ColorDome) to generate three types of stimuli that temporally modulated rods alone, cones alone, and rods and cones simultaneously. For each stimulus type, ERGs were recorded as a function of temporal frequency (2, 4, 8, or 16Hz) and mesopic light levels (0.02, 0.16, or 1.26cd/m(2)) in normal observers and patients with retinitis pigmentosa (RP) or cone-rod degeneration. The normal observers ERG waveforms showed a clear periodic pattern, mirroring the sinusoidal stimuli. At all light levels, rod responses were always higher than cone responses for temporal frequencies between 2 and 8Hz, suggesting that rods dominated the responses. Cone responses were minimal at the lowest light level and increased with increases in light level. The amplitude of the response to the combined stimuli was intermediate between that of the isolated cone and the isolated rod stimuli for all light levels. Good receptoral isolation was confirmed by the results showing (1) minimal or no rod ERGs but recordable cone ERGs in the patients and (2) high correlation between the ERG amplitudes obtained from the four-primary method and those from the ISCEV standard clinical protocol in normal observers.

Central Venous Catheter-Induced Cardiac Tamponade

Editori have read with great interest the review (1)written by Pittiruti et.al. followed by their multicenter study (2) regarding the use of EKG for central venous catheter (CVC) positioning.Late cardiac tamponade is a fatal complication that might arise if the CVC tip is left within the pericardial reflection by continuously eroding the atrial wall over time (3). it is there-fore that i do not understand why the authors in their study (2) aimed to position the CVCs so low. only procedures that require free blood flow (dialysis, hemofiltration, plasmapher-esis, etc.) are indications for a very low CVC position. in the review the authors claim that the EKG assisted CVC positioning technique is superior to fluoroscopy. Since EKG will position the CVC at the cava-atrial junction it will leave its tip within the pericardial reflection. Additional positioning as well as chest x-ray (CXR) is therefore required. Since CXR is needed to preclude other pathologies (such as pneumotho-rax) the use of expensive EKG catheters did not add any safety to the patients.The recommendations by Pittiruti in his review and study will expose patients to the danger of incorrect (deep) CVC position while using unnecessary expensive equipment. it is my recommendation to use the CVC lengths cited by Kim et. al. (4)and verify the position by CXR.

The Importance of Venous Doppler Velocimetry for Evaluation of Intrauterine Growth Restriction

The management of growth-restricted fetuses requires accurate diagnosis to optimize the timing of delivery. Doppler velocimetry is the only noninvasive method for assessing the fetoplacental hemodynamic status. This review will give a critical overview of the current knowledge on fetal venous blood flow in pregnancies complicated by in-trauterine growth-restricted fetuses. Adaptation of the circulation in intrauterine growth-restricted fetuses is described. Normal and abnormal venous Doppler waveforms are presented. Correlations of abnormal waveforms with the presence of acidemia and perinatal outcomes are emphasized. Limitations of venous Doppler velocimetry for optimizing the time for delivery and the perinatal outcome are also presented.

Axonal electrovisiogram as an electrophysiological test to evaluate optic nerve and inner retina electrical potentials: findings in normal subjects

To standardize and validate the technique of axonal electrovisiogram (AxEvg), defining its normative values and parameters and characterizing its findings in normal individuals. We enrolled 140 normal individuals (280 eyes) divided into seven groups according to age, each one with 10 males and 10 females. The technique was based on monocular visual stimulation by a 0 dB intensity bright flash on Ganzfeld bowl at a presentation rate of 1.4 Hz. Golden cup electrodes were used and electrical waves were acquired after artifact rejection. For each amplitude and implicit time peak we calculated the mean, median, pattern deviation, minimum and maximum values and 95% confidence interval. Monocular visual stimulation with bright flash under mesopic conditions was the standard technical procedure established. The normal AxEvg waveform consists of an initial positive wave (named P1, with mean amplitude of 2.0 mV and mean implicit time peak of 23.1 ms) followed by a negative wave (named N1, with mean amplitude of -3.9 mV and mean implicit time peak of 41.4 ms). No significant differences were observed between males and females or between right and left eyes, but there was an increased P1 and N1 implicit time peaks according to age. Implicit time characteristics suggest that P1 wave represents an optic nerve electrical potential and N1 wave represents an inner retinal layers potential. AxEvg can be considered a pre-chiasmatic visual evoked potential capable to reliably record the electrical activity of optic nerve and inner retina. The findings suggest that AxEvg may be useful as an electrophysiological test in the diagnosis of neuroretinal diseases.

Importance of Continuous Pulse Oximetry of the Ipsilateral Thumb/Index Finger during Transradial Angiography

We present a case of a 63-year-old male undergoing attempted basilar artery embolization using a right transradial artery approach in which continuous pulse oximetry of the ipsilateral thumb uncovered unanticipated hand ischemia during the procedure. A preprocedural evaluation using pulse oximetry of the right thumb demonstrated normal waveform and maintenance of normal oxygen saturation during manual compression of the right radial artery. This normal waveform and oxygen saturation was maintained after insertion of a 6Fr sheath into the radial artery. After insertion of a 6Fr guiding catheter into the right vertebral artery, near-complete dampening of the pulse oximetry waveform and precipitous decline in oxygen saturation were noted. Examination of the right hand demonstrated poor tissue perfusion. Immediate removal of the guiding catheter led to return of a normal waveform, oxygen saturation, and tissue perfusion. This case demonstrates the importance of continuous, intraprocedural monitoring of oxygenation of the ipsilateral hand during transradial angiography in order to avoid unanticipated perfusion abnormalities.

Doppler assessment of hepatic venous waves for predicting large varices in cirrhotic patients

Background/Aim:Color Doppler examination of changes in hepatic venous waveforms is being evaluated as a means of prediction of severity of portal hypertension and presence of esophageal varices. Normal hepatic venous waveform shows a triphasic pattern. In cirrhosis, this pattern changes to a biphasic or monophasic pattern. We aimed to study the sensitivity of loss of normal hepatic venous waveforms in predicting large varices in a cross-sectional analysis.Materials and Methods:All patients, admitted or attending the outpatient department, with a diagnosis of cirrhosis were included in the study. All patients were subjected to oesophagogastroduodenoscopy and Color Doppler examination, and waveform patterns in hepatic vein were recorded. The sensitivity and specificity of changes in waveform in detecting large varices were studied.Results:A total of 51 cases were examined. Triphasic waves were seen in 4 (7.8%) cases, biphasic in 26 (51%) cases, and monophasic in 21 (41.2%) cases. Small varices were seen in 30 (58.8%) cases and large varices in 21 (41.2%) cases. The sensitivity of loss of the triphasic wave pattern in detecting significant varices (Grade 3 or 4) was very high (95.23%) and negative predictive value was also high (75%). Severity of liver disease as indicated by Child-Pugh and MELD scores did not correlate with changes in hepatic venous waveforms.Conclusion:Loss of triphasic hepatic venous waveform is highly sensitive in predicting significant varices in patients with cirrhosis.