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F Kraus

Publications and source records attributed to F Kraus.

At least 37 records · Page 2Linked to original sources
PubMed1986

[Doppler echocardiography determination of the orifice area in aortic valve stenosis using a continuity equation].

The continuity equation, derived from the study of fluid mechanics, may serve as the basis for calculation of orifice area of stenosed cardiac valves. As applied to aortic stenosis, the continuity equation states that the flow across the narrowed valve is equal to the flow in the left ventricular (LV) outflow tract such that A1 X v1 = A2 X v2, where A1 = LV outflow tract area, v1 = prestenotic velocity, A2 = stenotic orifice area and v2 = poststenotic velocity. Accordingly, at each point in time during pulsatile flow, the respective valve orifice area can be calculated. Hence, from the sum of all areas throughout the ejection time, the mean valve orifice area can be constructed as integral of A2/ET = A1 X integral of (v1/v2)/ET, assuming A1 to be constant, where integral of denotes the integral over the ejection time ET. To assess the usefulness of this method with respect to its clinical relevance, in 36 patients with aortic stenosis, the Doppler echocardiographically-determined orifice areas were compared with those calculated by the Gorlin formula based on invasively-obtained data. LV outflow tract area A1 was measured by echocardiography from a parasternal long-axis view. Prestenotic velocity v1 was recorded in the LV outflow tract by pulsed Doppler from an apical transducer position, whereby care was taken in positioning the sample volume not too close to the stenotic valve to avoid the prestenotic area of increased velocity. Continuous-wave Doppler was used, usually from an apical or right parasternal transducer position, to record the stenotic jet velocity v2.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

[Doppler echocardiography determination of the pressure gradient and valve orifice area in mitral valve stenosis].

Pressure gradient and orifice area of stenosed mitral valves can be determined with Doppler echocardiography using the modified Bernoulli equation and the pressure half-time method, respectively (Figures 1 and 2). There was a close linear correlation between Doppler-echocardiographically determined pressure gradients and valve orifice areas with those obtained by invasive methods. In this study, in 85 patients with mitral stenosis of various severity, the valve orifice areas, as derived by the two methods respectively, correlated well (y = 0.89x + 0.15) with a correlation coefficient r = 0.96 and standard error of the estimate SEE = 0.12 cm2 (Figure 3). The correlation was not influenced by the prevailing cardiac rhythm, ventricular function, left ventricular mass or coexistent mitral or aortic regurgitation (Table 1). Accordingly, the Doppler echocardiographic method also appears applicable in the presence of concomitant mitral and aortic regurgitation which precludes an exact determination of valve orifice area with invasive methods. The Doppler echocardiographic method is currently so well validated that it can be regarded as a reliable noninvasive procedure for determination of the severity of mitral stenosis.

Blood Flow Velocity↗
PubMed1986

[Doppler echocardiography determination of the severity of tricuspid valve stenosis].

To evaluate the diagnostic usefulness of Doppler echocardiography for assessment of tricuspid stenosis, data of eleven patients were compared with hemodynamic results. Using the pressure half-time method, stenotic tricuspid orifice area was calculated as the quotient of 220 divided by the pressure half-time. The pressure gradient across the stenotic valve was determined according to the modified Bernoulli equation using four times the square of the maximal velocity of the stenotic jet. A close correlation was found between the Doppler echocardiographically and invasively determined orifice areas (r = 0.97, SEE = 0.23 cm2). There was also a good linear relationship between the pressure gradients derived from both methods (r = 0.89, SEE = 1 mmHg). Thus, the assessment of tricuspid stenosis can be achieved reliably by noninvasive means with the aid of Doppler echocardiography.

Adult↗
PubMed1985

[High-dose transdermal nitroglycerin therapy: loss of effect within 24 hours?].

Within a relatively short period of time, nitroglycerin patches have come into widespread use for treatment of coronary artery disease in the absence of sufficient clinical data in support of their efficacy. Presently, there is still considerable controversy regarding the extent and duration of action as well as the dosage requirements. Accordingly, a study was carried out in six patients with angiographically-documented coronary artery disease, stable exercise-induced angina pectoris and reproducible ST-segment depression to analyze the effects of nitroglycerin patches, formulated to deliver 5 mg, 10 mg, 20 mg as well as 30 mg per 24 hours, respectively, on the extent of ST-segment depression. In a further study, the extent and duration of antianginal and anti-ischemic effects of nitroglycerin patches delivering 30 mg/24 hours were investigated in ten patients according to a randomized, double-blind, crossover placebo-controlled protocol. In seven of these patients, testing was again performed at 2.5 hours after repeated application (second application at 24 hours) (Figure 1). Nitroglycerin patches delivering 5 mg, 10 mg, 20 mg as well as 30 mg/24 hours, respectively, led to significant reductions in ST-segment depression at 2.5 hours of 59% (range 25 to 100%; p less than 0.025), 63% (0 to 100%, p less than 0.01), 77% (50 to 100%, p less than 0.001) as well as 82% (50 to 100%, p less than 0.005) as compared with control values (Figure 2).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗
PubMed1984

Symptoms, exercise capacity and exercise hemodynamics: interrelationships and their role in quantification of the valvular lesion.

To compare the symptoms with the objectively-determined exercise capacity, the symptoms as well as the exercise capacity with the exercise hemodynamics and the symptoms, exercise capacity and exercise hemodynamics with the severity of the valvular lesion, in 154 patients with aortic regurgitation, mitral regurgitation, aortic stenosis or mitral stenosis, the symptoms were classified according to the New York Heart Association and the exercise capacity was determined by means of bicycle ergometry with simultaneous measurement of heart rate, blood pressure, pulmonary artery pressure, cardiac output and the left ventricular ejection fraction. Among the parameters studied, no relationships could be established; to a certain degree, the exercise hemodynamics correlated with the severity of the valvular lesion in that a markedly pathologic response was associated with the presence of a high-grade valvular lesion. Since the symptoms were not indicative of the exercise capacity, nor the symptoms or the exercise capacity of either the exercise hemodynamics, the exercise ejection fraction or the severity of the valvular lesion, the symptoms and the exercise capacity should be evaluated on the basis of the exercise hemodynamics before they are taken into consideration for meaningful decision-making processes such as establishment of the indication for surgery.

Adolescent↗
PubMed1983

[Detection and evaluation of infectious endocarditis].

Based on the findings of 50 patients with infective endocarditis, 37 affecting the aortic, six the mitral and seven both the aortic and mitral valves, in addition to analysis of predisposing factors, prominent signs and symptoms distinctive for the clinical entity were assessed (Tables 1 to 3). Preexistent conditions such as aortic valve lesions including bicuspid aortic valve as well as mitral valve lesions including mitral valve prolapse were proven in 66%. Factors which may have compromised host defense mechanisms such as cachexia and chronic alcohol or intravenous drug abuse were present in isolated cases. In 38% of the patients, a diagnostic or therapeutic manipulation, suspected to have given rise to the bacteremia, antedated the onset of endocarditis. Malaise, fatigue and chills were the most frequent symptoms (Table 4). Fever and cardiac murmurs were observed in all patients, anemia and bacteremia in 74% of the patients, respectively (Tables 4 to 6). In blood cultures, the most common microorganisms were found to be hemolytic and nonhemolytic streptococci accounting for 65% of positive findings, followed by enterococci and gram-negative bacteria each with 14% respectively (Table 6). Congestive heart failure predominated among cardiac complications with its occurrence in 84% of the patients. Valvular ring or myocardial abscess, aortic or sinus of Valsalva aneurysm, occasionally with perforation, were found in 24% of our patients. Coronary embolism was documented in 6%; infection-associated pericarditis was observed only rarely (Table 7). Extracardiac complications involved the skin, central nervous system, spleen and kidneys, respectively, in 20 to 30% of the patients. Complications afflicting the eyes, lungs, gastrointestinal tract and the musculo-skeletal system were seen with a lesser frequency of 0 to 12% (Table 8). The diagnosis of infective endocarditis, rendered highly-probable by the constellation of fever, cardiac murmur, bacteremia and anemia, necessitates, however, confirmation through cardiac examinations. In this respect, electrocardiographic and radiologic findings are of limited value, although they may be useful in the detection of cardiac complications. In 6% of the patients, positive criteria for myocardial infarction were indicative of coronary embolism and, i 30%, atrioventricular or fascicular block suggested the presence of abscess formation (Table 9). As radiologic evidence of heart failure, 74% of the patients were found to have pulmonary vascular congestion (Table 10).(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1981

Exercise testing in patients with valve replacement.

To determine whether detection of pathologic exercise hemodynamics can be based on assessment of noninvasive parameters, pulmonary artery pressure and cardiac output were measured during graded bicycle ergometry in 33 patients with mitral valve replacement and 42 patients with aortic valve replacement. No relationship could be established between exercise capacity, achievement of steady-state conditions of blood pressure and heart rate, the extent of heart rate increase and incurrence or extent of pathologic exercise hemodynamics. Thus, the results show that accurate evaluation of cardiovascular status during exercise in patients with valve replacement cannot be obtained without direct determination of the pressure-flow relationship.

Aortic Valve↗
PubMed1980

[Porphyria variegata].

Report of two patients with porphyria variegata. Several members of the first patient's family had abnormalities of porphyrine metabolism without having manifestations of porphyria. A biochemical screening of family members of PV patients is important because of its prophylactic value. In the second patient's family at least three persons have porphyria-like signs, but not all of them could be seen by us. Diagnosis, pathogenesis and therapy of porphyria variegata are discussed.

Adult↗