Noninvasive Diagnostic Procedures in Clinical Thrombosis
Hau C. Kwaan, Meyer M. Samama in Clinical Thrombosis, 2019
The presence of deep venous thrombi in the proximal major veins can be documented by measuring the rate of venous emptying of the calf following temporary venous occlusion with a thigh cuff. The volume of the calf can be calculated from measurements made with a strain gauge or estimated from changes in electrical impedance. Venous occlusion plethysmography using a mercury-in-rubber strain gauge was described in 1953 by Whitney.1 The principles have not changed, although Silastic® has replaced the rubber tubing.2 The strain gauge is placed around the maximum circumference of the calf. Circumference changes produce a proportional change in gauge length and electrical resistance. Thus, changes in calf volume can be calculated by measuring resistance changes. The impedance Plethysmograph provides similar information by measuring variations in the electrical resistance of the calf to passage of a weak AC current.3 The examination technique is essentially the same for strain gauge and impedance plethysmography.
Swelling of One Leg
K. Gupta, P. Carmichael, A. Zumla in 100 Short Cases for the MRCP, 2020
Diagnosis of deep vein thrombosis is difficult on clinical grounds alone. The following tests will help make a diagnosis: Venography.Impedance plethysmography.Radio-iodine-labelled fibrinogen leg scanning.Ultrasound/arthrogram.Lymphangiogram.
Miscellaneous Causes Of Unexplained Fever
Benedict Isaac, Serge Kernbaum, Michael Burke in Unexplained Fever, 2019
The impedance plethysmography technique, which is also noninvasive, is promising when used correctly; the changes in blood volume accompanying deep breathing are diminished in case of thrombosis.54 Combined with leg scanning it seems to be an excellent diagnostic tool.55 The radioactive fibrinogen test is a very sensitive screening method which depends on the preferential uptake of 125I-labeled human fibrinogen by a forming thrombus. It has, however, some limitations.53,54
Neighbourhood deprivation in childhood and adulthood and risk of arterial stiffness: the Cardiovascular Risk in Young Finns study
Published in Blood Pressure, 2023
Erika Kähönen, Satu Korpimäki, Markus Juonala, Mika Kähönen, Terho Lehtimäki, Nina Hutri-Kähönen, Olli T. Raitakari, Mika Kivimäki, Jussi Vahtera
Measurements of arterial PWV were performed in 2007 with a whole-body impedance cardiography device (CircMonR, JR Medical Ltd, Tallinn, Estonia). The method includes whole-body impedance cardiography, distal impedance plethysmography, and an ECG channel. Standard electrodes were placed on the body surface: for the whole-body impedance measurement a pair of current electrodes on the wrist and ankles, and a pair of voltage electrodes 5 cm proximal to the aforementioned current electrodes, and for the distal impedance plethysmography measurement the active electrode on the lateral side of the knee joint and reference electrode about 20 cm distal to it on the calf. The method registers continuous changes in body electrical impedance during a cardiac cycle. The whole-body impedance decreases when the pulse pressure wave enters the aortic arch and popliteal artery impedance decreases when the pulse pressure wave later enters the lower limb. The aortic-popliteal PWV can be calculated by the CircMonR device software from the pulse transit time and the approximate distance between the aortic arch and the popliteal artery. The measurement method and its validation procedure have been introduced in detail earlier (Aatola et al. 2010; Kööbi et al. 2003). This method has been detected to have good repeatability and reproducibility values and measurements have excellent correlation (r = 0.82) with tonometric PWV method measurements (Tahvanainen et al. 2009; Wilenius et al. 2016).
Association of non-invasive hemodynamics with arterial stiffness in rheumatoid arthritis
Published in Scandinavian Cardiovascular Journal, 2018
Panagiota Anyfanti, Areti Triantafyllou, Eugenia Gkaliagkousi, Nikolaos Koletsos, Spyros Aslanidis, Stella Douma
Available data regarding the association between central hemodynamics and macrovascular impairment in RA are extremely limited. PWV has been associated with left ventricular dysfunction in 40 patients with RA, evaluated by use of tissue Doppler-derived myocardial performance index [25]. LVET, yet no other indices from impedance cardiography, was identified as a determinant of PWV in young, healthy males [26]. On the other hand, the negative impact of conventional cardiovascular risk factors on arterial stiffness has been observed also in RA patients [7]. Moreover, the interplay between systemic inflammation and autoimmune dysregulation in RA, which emerges as an appropriate substrate for the development and progression of macrovascular dysfunction, has been well-described [10,27]. In the present study, the non-significant effect of central hemodynamics on PWV in the multivariate analysis might be explained by the fact that with the exception of TFCI, all other indices were comparable between patients and healthy controls and therefore, not profoundly impaired (Table 1). In addition, rheological disorders and myocardial dysfunction most probably are the exact derivative of the effect of classical cardiovascular risk factors on the cardiovascular system. In any case, impedance cardiography can be helpful in terms of hemodynamic characterization of these patients.
Renal sympathetic denervation lowers systemic vascular resistance in true treatment-resistant hypertension
Published in Blood Pressure, 2021
Kaja K. Bergo, Anne C. Larstorp, Pavel Hoffmann, Ulla Hjørnholm, Alessandro Cataliotti, Aud Høieggen, Morten Rostrup, Fadl Elmula M. Fadl Elmula
The change in SVRI between baseline and 6 months was not significant in either group. At baseline, impedance cardiography is an unfamiliar procedure for most patients, and the information that the procedure involves trans-thoracic transfer of a low magnitude electrical current (although unnoticeable) could trigger nervousness and a fight-flight response. A fight-flight response with elevated sympathetic activation leads to increased heart rate and skeletal muscle vasodilation as seen in both groups at baseline [28]. At the three months follow-up the patients are more familiar with the procedure, and SVRI and heart rate are returned to their general hypertensive pathophysiological state with higher SVRI level and lower heart rate compared to baseline. From three to six months follow-up, the treatments in both groups can explain the subsequent reduction in SVRI, and a reflex increase in heart rate.
Related Knowledge Centers
- NON-Invasive Procedure
- Stroke Volume
- Heart Rate
- Cardiac Output
- Aorta
- Cardiac Cycle
- Electrical Cardiometry
- Hemodynamics
- Ohm'S Law
- Aortic Valve