Search PubMed⌕ Search

Biomedical subjects

A Kardos

Publications and source records attributed to A Kardos.

43 records · Page 3Linked to original sources
PubMed1991

[Doppler echocardiography in the examination of normally functioning artificial mitral and aortic valves].

Patients with prosthetic valves were investigated by Doppler echocardiography in 902 cases between November 1987 and February 1990. The parameters of 209 of 344 mitral and 258 of 299 aortic prosthetic valves were evaluated. No significant correlation was found between the type of aortic or mitral prosthetic valves and the measured gradient. As concerns the size of the valve and the measured gradient, a close correlation for aortic valve replacement was detected. For a normally functioning mitral prosthetic valve, a maximum early diastolic velocity of less than 2 m/s (16 mm Hg gradient) and a pressure half-time of less than 130 ms (mitral valve area 1.8 cm2) were characteristic. In cases of aortic valve replacements, the maximum velocity was less than 3 m/s (36 mm Hg gradient), except for the small-diameter valves. More than 95% of the cases met these criteria. (Even if small-diameter valves were included, a maximum velocity of more than 3 m/s occurred only in 8.9%.) Doppler echocardiography is a suitable tool for detecting normal prosthetic valve function, while colour Doppler allows the optimal alignment of jet direction and Doppler beam.

Aortic Valve Insufficiency↗
PubMed1991

[Systemic thrombolysis in acute obstruction of an artificial valve].

Prosthetic valve thrombosis is a characteristic, but fortunately not frequent complication of surgical valve replacement. Its occurrence may lead to haemodynamic catastrophe. Three cases involving prosthetic valve thrombosis are presented. Two patients suffered from thrombosis after tricuspid valve replacement (St. Jude Medical), while the third occurred after mitral valve replacement (Sorin). In the acute phase, systemic thrombolysis was initiated (2 MU Streptokinase during 22-28 hours). The obstruction of one of the tricuspid valves and the mitral valve was eliminated. Lysis of the other tricuspid valve was not complete, but it helped the patient to survive the acute phase until reoperation. Embolization occurred in the inferior extremity after thrombolysis of the mitral prosthetic valve, but it was cured. Two-dimensional and Doppler echocardiography (conventional and colour-coded) played an important role in the diagnosis of the obstruction and in the follow-up of the effectivity of thrombolysis. Systemic thrombolysis may be a lifesaving procedure in acute prosthetic valve thrombosis. In spite of the potentially dangerous complications, it has to be attempted.

Adult↗
PubMed1991

[Judging the severity of regurgitation in acquired heart defects using color-coded Doppler echocardiography].

In the study, 139 valvular regurgitations of 120 patients (55 mitral and 84 aortic regurgitations) were investigated and compared by means of colour flow mapping and heart catheterization. During the echocardiographic examination, the length and width of the regurgitant jets were measured and the jet area was planimetered besides the subjective grades. The above parameters were correlated with the angiographic grades. Good agreement was found between the results of the two methods. As concerns the different parameters of the regurgitant jets in mitral regurgitation, the most severe (grade IV) category was easily distinguished from the others, while in aortic regurgitation all four categories were differentiated by colour flow mapping. These measurements indicated that colour-coded Doppler echocardiography is a suitable tool for detection of the severity of valvular regurgitations in a noninvasive way.

Aortic Valve Insufficiency↗
PubMedDate not supplied

Isometric handgrip exercise-induced muscarinic vasodilation in the human skin microvasculature.

The existence of an active vasodilator system in the human skin microvasculature is well documented, but its physiological role and the underlying mechanisms are not completely understood. Cutaneous blood flow increases during isometric handgrip exercise. To examine whether this response is mediated by active vasodilation, isometric handgrip exercise testing was performed in nine healthy subjects. Local iontophoresis of atropine was applied to the forearm skin. Skin blood flow (SBF) monitoring by means of laser Doppler flowmetry was combined with continuous noninvasive blood pressure monitoring. SBF monitoring was performed at a site pretreated with atropine and an adjacent control area. Mean arterial pressure (MAP) was recorded noninvasively. Cutaneous vascular resistance (CVR) was calculated as MAP/SBF for the atropine treated and the control areas. Changes in CVR were expressed as percent deviation from the baseline (dCVR). Isometric handgrip exercise resulted in a marked reduction in CVR at the control site (dCVR: -66 +/- 4%). In contrast, the CVR was not significantly altered at the atropinetreated site (2.4 +/- 7%). It is concluded that isometric exercise induces an atropine-sensitive vasodilation which is mediated by muscarinic receptors in the human skin.

Adult↗
PubMedDate not supplied

The effects of patterned breathing and continuous positive airway pressure on cardiovascular regulation in healthy volunteers.

1. Although the increased heart rate variability in healthy subjects in association with slow patterned breathing and continuous positive airway pressure is well documented, there is no general agreement regarding the underlying mechanism. The arterial baroreceptor stimulation due to greater blood pressure variability, the stimulation of pulmonary stretch and low pressure baroreceptors can play important role in this phenomenon. 2. In order to assess the interplay between blood pressure and heart rate changes we have studied nine healthy volunteers (mean age was 22 yrs. range 19-24), by applying 6/min patterned breathing, and continuous positive airway pressure of 10 cm of water. ECG and finger blood pressure (Finapres 2300) was continuously recorded. The oscillation amplitude of R-R intervals were analysed as well as the time and frequency domain indexes of heart rate variability. The oscillation amplitude and the corresponding frequency domain components of systolic blood pressure were also calculated. 3. The forced deep breathing caused significant increase in heart rate variability as indicated by time and frequency domain analysis of R-R intervals (LF HRV ms2: spontaneous: 777.40 +/- 526.1, patterned breathing 6828.00 +/- 5468.0). The application of CPAP in the same rhythm during patterned breathing resulted in further enhancement in heart rate variability (LF HRV ms2: 9052.00 +/- 4533.0). The analysis of the same frequency domain components of systolic blood pressure showed marked elevation of the total and low frequency power during patterned breathing. (LF BPV mm Hg2: spontaneous: 8.24 +/- 6.2, patterned breathing: 16.22 +/- 9.7). Applying CPAP with the same breathing pattern elicited further significant increment in systolic blood pressure fluctuation (LF BPV mm Hg2: deep breathing + CPAP: 27.11 +/- 9.8). The baroreflex sensitivity as calculated from spontaneous HR and BP sequences was 11.66 +/- 2.9 at baseline and increased to 17.66 +/- 6.1 and changed to 15.22 +/- 3.2 with the addition of patterned breathing and CPAP, respectively. 4. Our findings indicate that the heart rate and blood pressure responses to slow patterned breathing may be interpreted as consequences of an altered baroreflex sensitivity. In contrast the active breathing with CPAP exerts mechanical effects which in turn present an augmented systemic baroreflex trigger, however, the baroreflex sensitivity remains unchanged.

Adult↗
PubMedDate not supplied

Short-term monitoring of the vascular resistance of the human skin microvasculature.

OBJECTIVE AND METHOD: Laser Doppler flowmetry is a non-invasive tool in assessing the temporary changes of skin microcirculation. Another non-invasive equipment the Finapres 2300 finger blood pressure monitor provides a continuous blood pressure signal. The combination of the two devices allows short-term monitoring of the changes in the resistance of skin microvasculature. In order to assess the role of skin blood vessels in physiological responses to complex reflex tests Valsalva manoeuvre was performed by 12 healthy volunteers. For comparison a thermal stimulation (cold pressor) test was also done. RESULTS: The two tests resulted in skin blood flow responses of similar magnitude. The changes in calculated regional peripheral resistance (dRPR) indicated that both responses involved active vasoconstrictor mechanisms. It is of importance that the active vasoconstriction could be documented only at the late strain phase (V2) but not in the early strain phase (V1) of the Valsalva manoeuvre (%dRPR in V1 = 0.14 vs. V2 = 0.96, p < 0.05). CONCLUSIONS: In conclusion our findings support the theory that changes in the tone of the skin blood vessels parallel the changes in systemic vasculature in response to complex reflex tests. This is the first report which documents the feasibility of the continuous monitoring of the regional peripheral resistance.

Adolescent↗