Absence of supernormal conduction in canine myocardium

1983 ◽  
Vol 61 (3) ◽  
pp. 207-212
Author(s):  
D. Leigh Carson ◽  
Peter E. Dresel
Keyword(s):  
Arrival Time ◽  
Left Ventricular ◽  
Conduction Time ◽  
Recording Site ◽  
Myocardial Wall ◽  
Adjacent Site ◽  
The Difference ◽  
Myocardial Muscle ◽  
Retrograde Conduction ◽  
Canine Myocardium

Transmural conduction time, measured as the difference in arrival time of impulses from a distant stimulating site at endocardial and epicardial electrodes near the left ventricular apex, has been reported to decrease when closely coupled extrasystoles are interpolated, indicating that muscle conduction could be supernormal. We have now determined that reduction in transmural conduction time is accounted for completely by the relatively late arrival time of the extrasystolic wave front at the endocardial recording site. The endocardial recording site was activated later than an immediately adjacent site within the wall in two out of eight animals, which could be interpreted as retrograde conduction. No evidence for supernormal conduction within the ventricular wall could be obtained by multiple electrode recordings. Supernormal conduction throughout the myocardial wall could not be demonstrated on stimulation of the endocardial site. We conclude that supernormal conduction in myocardial muscle cannot be demonstrated and that changes in transmural conduction time do not always measure myocardial conduction velocity.

Basic determinants of epicardial transudation

1997 ◽  
Vol 273 (3) ◽  
pp. H1408-H1414 ◽  
Author(s):  
R. H. Stewart ◽  
D. A. Rohn ◽  
S. J. Allen ◽  
G. A. Laine
Keyword(s):  
Reflection Coefficient ◽  
Coronary Sinus ◽  
Myocardial Edema ◽  
Hydraulic Conductance ◽  
Linear Increase ◽  
Left Ventricular ◽  
Edema Formation ◽  
Anesthetized Dogs ◽  
The Difference ◽  
Osmotic Reflection Coefficient

Myocardial edema formation, which has been shown to compromise cardiac function, and increased epicardial transudation (pericardial effusion) have been shown to occur after elevation of myocardial venous and lymphatic outflow pressures. The purposes of this study were to estimate the hydraulic conductance and osmotic reflection coefficient for the epicardium and to determine the effect of coronary sinus hypertension and cardiac lymphatic obstruction on epicardial fluid flux (JV,e/Ae). A Plexiglas hemispheric capsule was attached to the left ventricular epicardial surface of anesthetized dogs. JV,e/Ae was determined over 30-min periods for three intracapsular pressures (-5, -15, and -25 mmHg) and two intracapsular solutions exerting colloid osmotic pressures of 7.0 and 2.0 mmHg. Hydraulic conductance was estimated to be 3.7 +/- 0.5 microliters.h-1.cm-2.mmHg-1. An osmotic reflection coefficient of 0.9 was calculated from the difference in JV,e/Ae of 16.5 +/- 8.4 microliters.h-1.cm-2 between the two solutions. Graded coronary sinus hypertension induced a linear increase in JV,e/Ae, which was significantly greater in dogs without cardiac lymphatic occlusion than in those with occlusion.

Effects of avertin versus xylazine-ketamine anesthesia on cardiac function in normal mice

2001 ◽  
Vol 281 (5) ◽  
pp. H1938-H1945 ◽  
Author(s):  
Chari Y. T. Hart ◽  
John C. Burnett ◽  
Margaret M. Redfield
Keyword(s):  
Cardiac Function ◽  
Diastolic Pressure ◽  
Systolic Function ◽  
Pressure Rise ◽  
Left Ventricular ◽  
Lv Function ◽  
Ketamine Anesthesia ◽  
The Difference ◽  
And Function ◽  
Derivatives Of

Anesthetic regimens commonly administered during studies that assess cardiac structure and function in mice are xylazine-ketamine (XK) and avertin (AV). While it is known that XK anesthesia produces more bradycardia in the mouse, the effects of XK and AV on cardiac function have not been compared. We anesthetized normal adult male Swiss Webster mice with XK or AV. Transthoracic echocardiography and closed-chest cardiac catheterization were performed to assess heart rate (HR), left ventricular (LV) dimensions at end diastole and end systole (LVDd and LVDs, respectively), fractional shortening (FS), LV end-diastolic pressure (LVEDP), the time constant of isovolumic relaxation (τ), and the first derivatives of LV pressure rise and fall (dP/d t max and dP/d t min, respectively). During echocardiography, HR was lower in XK than AV mice (250 ± 14 beats/min in XK vs. 453 ± 24 beats/min in AV, P < 0.05). Preload was increased in XK mice (LVDd: 4.1 ± 0.08 mm in XK vs. 3.8 ± 0.09 mm in AV, P < 0.05). FS, a load-dependent index of systolic function, was increased in XK mice (45 ± 1.2% in XK vs. 40 ± 0.8% in AV, P < 0.05). At LV catheterization, the difference in HR with AV (453 ± 24 beats/min) and XK (342 ± 30 beats/min, P < 0.05) anesthesia was more variable, and no significant differences in systolic or diastolic function were seen in the group as a whole. However, in XK mice with HR <300 beats/min, LVEDP was increased (28 ± 5 vs. 6.2 ± 2 mmHg in mice with HR >300 beats/min, P < 0.05), whereas systolic (LV dP/d t max: 4,402 ± 798 vs. 8,250 ± 415 mmHg/s in mice with HR >300 beats/min, P < 0.05) and diastolic (τ: 23 ± 2 vs. 14 ± 1 ms in mice with HR >300 beats/min, P < 0.05) function were impaired. Compared with AV, XK produces profound bradycardia with effects on loading conditions and ventricular function. The disparate findings at echocardiography and LV catheterization underscore the importance of comprehensive assessment of LV function in the mouse.

scholarly journals RBP: a website fingerprinting obfuscation method against intelligent fingerprinting attacks

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Tao Luo ◽  
LiangMin Wang ◽  
ShangNan Yin ◽  
Hao Shentu ◽  
Hui Zhao
Keyword(s):  
Data Security ◽  
Arrival Time ◽  
State Of The Art ◽  
Web Security ◽  
Security And Privacy ◽  
Low Delay ◽  
Defense Technology ◽  
The Difference ◽  
Bandwidth Overhead ◽  
Traffic Analysis Attack

AbstractEdge computing has developed rapidly in recent years due to its advantages of low bandwidth overhead and low delay, but it also brings challenges in data security and privacy. Website fingerprinting (WF) is a passive traffic analysis attack that threatens website privacy which poses a great threat to user’s privacy and web security. It collects network packets generated while a user accesses website, and then uses a series of techniques to discover patterns of network packets to infer the type of website user accesses. Many anonymous networks such as Tor can meet the need of hide identity from users in network activities, but they are also threatened by WF attacks. In this paper, we propose a website fingerprinting obfuscation method against intelligent fingerprinting attacks, called Random Bidirectional Padding (RBP). It is a novel website fingerprinting defense technology based on time sampling and random bidirectional packets padding, which can covert the real packets distribution to destroy the Inter-Arrival Time (IAT) features in the traffic sequence and increase the difference between the datasets with random bidirectional virtual packets padding. We evaluate the defense against state-of-the-art website fingerprinting attacks in real scenarios, and show its effectiveness.

Left Side Right Ventricular Cardiomyopathy

2002 ◽  
Vol 42 (4) ◽  
pp. 313-317 ◽  
Author(s):  
M Michalodimitrakis ◽  
A Papadomanolakis ◽  
J Stiakakis ◽  
K Kanaki
Keyword(s):  
Right Ventricular ◽  
Arrhythmogenic Right Ventricular Cardiomyopathy ◽  
Left Ventricular ◽  
Muscle Disease ◽  
Pathologic Examination ◽  
Arrhythmogenic Cardiomyopathy ◽  
Ventricular Cardiomyopathy ◽  
First Case ◽  
Fibrofatty Tissue ◽  
Myocardial Muscle

Arrhythmogenic right ventricular cardiomyopathy or dysplasia, a heart muscle disease of unknown cause, is anatomically characterized by variable replacement of myocardial muscle with adipose or fibroadipose tissue. It is usually considered a selective disorder whereas concomitant left ventricular involvement has been noted in a few cases. Two cases of the disease with evidence of extensive left ventricular involvement at pathologic examination are described. Hearts from two patients who died suddenly showed extensive biventricular infiltration by fibrofatty tissue in the first case and exclusively in the wall of the left ventricle the localization of the fatty and fibrotic lesions. These findings might suggest that the various localizations of the fibroadipose tissue are rather different expressions of the same disease and it is preferable to be termed ‘arrhythmogenic cardiomyopathy’ as other studies also indicate.

scholarly journals ENGINEERING OF ACOUSTIC TECHNOLOGY FOR UNDERWATER POSITIONING OBJECT

2018 ◽  
Vol 10 (3) ◽  
pp. 629-637
Author(s):  
Billi Rifa Kusumah ◽  
Indra Jaya ◽  
Henry M. Manik ◽  
. Susilohadi
Keyword(s):  
Control System ◽  
Sound Source ◽  
Arrival Time ◽  
Equation Model ◽  
Control Device ◽  
Electromagnetic Signal ◽  
Positioning System ◽  
Underwater Sound ◽  
Underwater Positioning ◽  
The Difference

Underwater Positioning System (UPS) is a system to track the existence of the position of an object by utilizing the arrival time of the signal measurement. On land, the system uses an electromagnetic signal called GPS. However, because it cannot penetrate water effectively, an acoustic signal is used as an alternative. The purpose of this research is to engineer the control system of data acquisition and underwater acoustic device to measure arrival time (TOA) and apply equation model for underwater sound source positioning system. the effective frequency resonance of the transducer and the hydrophone is at a frequency of 6 kHz. The acquisition control device is able to measure the TOA signal with an error on a digital channel smaller than an analog channel. The difference between the TOA values measured by oscilloscope and acquisition control system is caused by inaccuracy of threshold estimates at the receiver's peak detector circuit. The position of the sound source coordinates obtained from the equation model shows the highest difference in depth point (z) compared to points (x) and (y), caused by the equation model used is limited to four hydrophone units forming a horizontal baseline.

scholarly journals Relationship between episodes of unsustained VTs detected early after an ICD implant and subsequent monomorphic VTs causing appropriate therapy

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
J Jimenez-Candil ◽  
J Perez ◽  
M Sanchez ◽  
J Hernandez ◽  
J.L Morinigo ◽  
...  
Keyword(s):  
Estimating Equation ◽  
Left Ventricular ◽  
Adjusted Risk ◽  
Bland Altman Method ◽  
Appropriate Therapy ◽  
The Difference ◽  
Mean Cycle ◽  
Ventricular Tachycardias ◽  
The Relationship

Abstract Introduction Non-sustained ventricular tachycardias (NSVT) are observed frequently among ICD patients with left ventricular dysfunction (LVD). Purpose To analyze the relationship between episodes of NSVTs and monomorphic VTs (MVTs) that subsequently cause appropriate therapies. Methods 416 ICD patients with LVD (LVEF &lt;45%) followed for 41±27 months. ICD programming (detection and therapies) was standardized. NSVT was defined as any VT of ≥5 beats which did not met the detection criteria occurring within the first 6 months after ICD implant. We analyzed 2201 NSVTs (10+7 beats), which occurred in 250 of the 416 patients (Median=2; IQR=0–7). The mean cycle length (CL) of NSVT was 323±32 ms (adjusted per multiple episodes/patient, generalized estimating equation method (GEEM)). Results During the follow-up, 1441 MVT occurred in 183 patients. After showing a significant correlation between burden of NSVT and the occurrence of appropriate therapies due to MVT (C coefficient=0.68; p&lt;0.001), we observed that subjects with &gt;5 NSVT presented an excess of adjusted risk: HR=1.97 (95% CI=1.45–2.72); p&lt;0.001. However, the adjusted mean CL of NSVTs was similar in patients with (322±34) vs. without MVT (324±26 ms); p=0.3. Among patients who presented NSVTs and MVTs (n=145 subjects), we analyzed the relationship between the adjusted mean CL of the NSVTs (n=1288 episodes) and the CL of the first appropriate therapy due to MVT occurring subsequently. We found a significant and positive correlation between the two (r=0.88; p&lt;0.001); the strongest correlation was observed in subjects with &gt;5 NSVTs (r=0.97, n=52)). The robustness of such correlation was similar in individuals with ischemic (r=0.86; n=91) versus non-ischemic cardiomyopathy (r=0.90; n=54), and in primary (r=0.86; n=75) versus secondary prevention (r=0.90; n=70). The agreement between the CL of first MVT and the adjusted mean CL of NSVT episodes (GEEM) was determined according to the Bland-Altman Method. The difference between the two values was 2±8.3 ms, with only 7.6% (11/145) of patients in whom the difference between the two CL was outside the concordance limits. The agreement was greater, again, in individuals with &gt;5 NSVTs. As shown in the Figure, in more than 95% of patients both values were within the interval of agreement (0.32±4 ms). Conclusions 1-The burden of NSVTs occurring early after an ICD implant, but not their CL, is associated with a higher incidence of appropriate therapies due to MVT at follow-up. 2-The CL of the NSVTs and that of the first and subsequent MVTs is virtually the same in patients with higher NSVT burden. Therefore, it could be the same tachycardia, but with different duration. Figure 1 Funding Acknowledgement Type of funding source: None

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