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Biomedical subjects

D Burckhardt

Publications and source records attributed to D Burckhardt.

At least 91 records · Page 5Linked to original sources
PubMed1982

[Non-invasive evaluation of pressure gradients in aortic stenosis using Doppler ultrasound].

In 35 consecutive patients with aortic stenosis, noninvasive assessment of pressure gradients was performed using a continuous wave Doppler ultrasound technique prior to left heart catheterization. Maximum blood flow velocity in the ascending aorta and time from aortic valve opening to peak velocity in relation to left ventricular ejection time (TPV) were measured. Doppler data proved reliable in predicting a pressure gradient above or below 50 mm Hg (sensitivity 89% and specificity 88%). Pressure gradients calculated from the frequency shift of the ultrasound wave correlated well with pressure measurements obtained at cardiac catheterization in 31 patients with adequate Doppler velocity signals (r = 0.85, p less than 0.001). In all 4 patients with inadequate velocity signals a pressure gradient above 50 mm Hg could still be predicted by an abnormally delayed timing of peak velocity in systole (TPV greater than 0.5).

Adolescent↗
PubMed1982

[Non-invasive determination of pressure gradients of heart valve prostheses using Doppler ultrasound].

Noninvasive measurements of pressure gradients by continuous wave Doppler ultrasound technique were carried out in 40 patients with correctly functioning heart valve prostheses (10 Björk-Shiley in aortic position, 10 Björk-Shiley in mitral, 10 St. Jude Medical in aortic and 10 St. Jude Medical in mitral) and in 10 patients with normal aortic and 10 patients with normal mitral valves. The pressure gradients were slightly but significantly higher in prosthetic than in normal heart valves (p less than 0.005). Pressure gradients in Björk-Shiley prostheses were higher than in St. Jude Medical prostheses both in aortic (18.4 +/- 2.6 vs 9.6 +/- 1.9; p less than 0.01) and in mitral position (8.2 +/- 1.1 vs 5.4 +/- 0.8; p less than 0.05). The pressure gradient was inversely related to valve size in Björk-Shiley prostheses (r = -0.60 for aortic and r = -0.42 for mitral valves; p less than 0.05) but not in St. Jude Medical prostheses. The non-invasive Doppler technique should be useful in the diagnosis of prosthetic valve obstruction.

Aortic Valve↗
PubMed1982

[Creatine kinase (CK) activity and its isoenzyme MB in the serum of randomly selected patients without acute coronary disease].

Elevations of creatine kinase (CK) are not specific for myocardial disease. However, enzyme release due to extracardial factors is not necessarily comparable in healthy and diseased persons. It is therefore questionable whether normal values obtained in a group of healthy or mildly ill subjects are also valid for severely ill patients. The activity pattern of CK and its isoenzyme MB was therefore examined in the serum of 100 consecutive patients attending the medical outpatient clinic and of 170 patients at the time of admission to the medical emergency ward. The clinical and laboratory findings and diagnoses for all patients are recorded. Acute coronary disease was excluded. Determination of CK was performed according to the method described by Oliver [21] and Preston [27], but the results were calculated for a reaction temperature of 30 degrees C and determination of CK-MB was in cue with the method described by Prellwitz [25]. 4% of the outpatients and 14% of the emergency patients had CK values of over 100 U/1. In the majority of the patients (19 of 28) with CK values of over 100 U/1, the history revealed that the elevated values could be attributed to skeletal muscle trauma. After these values had been excluded, the 95% percentile was 20-85 U/1 (outpatients) and 20-110 U/1 (emergency ward) for men and 15-90 U/1 (outpatients) and 20-75 U/1 (emergency ward) for women. Without this selection, the newly admitted male patients in particular would have presented considerably elevated values. Since an explanation was found for most of the elevating values, the adjusted figures show no major differences between outpatients and hospital patients. The limit for CK-MB activity indicative of cardiac origin is presumed to be between 4-10% of the total CK activity. However, individual variations are observed, since CK-MB activity in skeletal muscle in variable and atypical isoenzymes may interfere with CK-MB determination. In this study 14% of the patients admitted to the emergency ward with CK values of under 100 U/1 presented false positive CK-MB values of over 10% of the total CK activity. It is concluded that CK-MB determination using the antibody method does not afford reliable results when there is no elevation of total CK.

Adult↗
PubMed1982

Accuracy of serial myocardial perfusion scintigraphy with thallium-201 for prediction of graft patency early and late after coronary artery bypass surgery. A controlled prospective study.

To assess the accuracy of serial myocardial perfusion scintigraphy with thallium-201 (201Tl) to predict graft patency early and late coronary artery bypass surgery, rest and exercise 201Tl and coronary arteriography were performed preoperatively and 2 weeks and 1 year after operation. The scintigraphic results were compared with graft patency, symptoms, left ventricular function and physical work capacity in a consecutive series of 55 patients with a total of 154 grafts. Serial 201Tl had an 80% sensitivity, 88% specificity and 86% overall accuracy in detecting or excluding graft occlusion, which was predicted by reversible ischemia as well as persistent "new scar" segments. Occluded grafts were correctly localized by 201Tl scintigraphy in 61%. Postoperative apical 201Tl defects were frequent (two-thirds of cases), and were the result of intraoperative transapical venting of the left ventricle. After coronary bypass graft surgery, ejection fraction at rest was unchanged. Left ventricular end-diastolic pressure and physical work capacity improved significantly. In the presence of new perfusion defects detected postoperatively, physical work capacity was reduced significantly. New 201Tl defects in addition to typical or atypical angina provided a high probability of graft occlusion, while in the absence of new 201Tl defects all grafts were patent in more than 90% of patients, all of whom had no or only atypical chest pain. We conclude that serial 201Tl imaging after coronary artery bypass surgery is an accurate noninvasive method that can be used routinely to assess graft function, to localize spatially occluded grafts and to identify patients with a high likelihood of graft occlusion who may need invasive studies.

Angina Pectoris↗
PubMed1982

Evidence for an augmented glucagon dependence of hepatic glucose production in cirrhosis of the liver.

The role of endogenous glucagon in maintaining hepatic glucose production after an overnight fast in patients with cirrhosis of the liver was studied with arterial-hepatic-venous catheterization and using somatostatin to suppress glucagon secretion. Arterial glucagon levels were elevated in eight cirrhotics to 290 +/- 90 pg/ml (SEM) compared to 100 +/- 10 pg/ml (P less than 0.02) in five normal controls, and they were lowered during administration of somatostatin (SRIF; 250 microgram/h) by a mean of 154 pg/ml and 39 pg/ml in cirrhotics and controls, respectively. Basal net splanchnic glucose production (NSGP) was similar in patients with and without cirrhosis (approximately 100 mg/min) but declined more markedly during 30 min of SRIF in cirrhotics to a net splanchnic uptake of glucose of 30 +/- 20 ml/min, as opposed to a fall of NSGP by 44 +/- 2 mg/min in controls (P less than 0.01). To assure that NSGP declined during SRIF infusion due to the fall of glucagon levels, SRIF was combined with a glucagon infusion at 150 ng/m2 . min in four cirrhotics and in five control subjects. Arterial glucagon levels were elevated to a mean of 650 pg/ml and 559 pg/ml in cirrhotics and controls, respectively. NSGP increased after 40 min of SRIF and glucagon replacement to 179 +/- 33 mg/min in cirrhotics and significantly more, to 412 +/- 68 mg/min, in controls (P less than 0.01). Thus, hepatic glucose production during basal and elevated glucagon levels suggested hepatic resistance to glucagon in cirrhosis. Nevertheless, endogenous glucagon played an augmented stimulatory role in maintaining glucose production in the normal range since there was an exaggerated fall of hepatic glucose output during glucagon suppression.

Aged↗
PubMed1981

[Atrioventricular block after carotid pressure in hypothyroidism: normalisation after substitution treatment (author's transl)].

Severe auto-immune hypothyroidism, probably after hyperthyroidism, was diagnosed in a 79-year-old woman with hypothyroidism (T3 and T4 immeasurably low) without the classical signs of myxoedema heart. On carotid sinus pressure transitory first degree AV block occurred and, on one occasion, complete AV block. This response disappeared after substitution treatment for four weeks with 50 microgram L-thyroxine. Further examination half a year later, on a maintenance of 75 microgram thyroxine, also gave a negative response to carotid sinus pressure.

Aged↗
PubMed1981

[Metabolic evaluation and etiology of "preclinical hypothyroidism": a preliminary report].

The TRH test, using synthetic TRH (TSH-releasing hormone) is the most sensitive test for the assessment of thyroid function. It may show elevated basal TSH and/or an exaggerated TSH response to TRH, despite normal thyroid hormone levels (T4, FT4I, T3). This condition is termed "preclinical hypothyroidism" (pc hypo). Thyroid hormone levels, the clinical index of Billewicz and metabolic impact on target tissues were studied prospectively in 38 pc hypo women and compared with 20 controls matched for age, weight and sex and 9 patients with overt hypothyroidism. For metabolic evaluation at the tissue site two new metabolic tests were developed and standardized, the systolic time intervals (STI) and sex-hormone-binding globulin (SHBG), which were used in conjunction with the ankle reflex time (ART) and lipids (cholesterol and triglycerides). The thyroid hormones T4, FT4I and T3 in pc hypo (77.8 +/- 2.0 nmol/l; 71.8 +/- 2.3; 1.92 +/- 0.07 nmol/l respectively; mean +/- SEM) were within the normal range (by definition), but significantly lower in comparison with the normal controls (105.5 +/- 3.3 nmol/l; 97.8 +/- 3.1; 2.91 +/- 0.12 nmol/l respectively; p less than 0.001). The clinical index and metabolic parameters SHBG and ART showed significant hypothyroid changes. STI (measured as preejection period) and lipids were not yet significantly different from the controls despite a hypothyroid tendency in many single individuals. The etiology in 144 patients with pc hypo (out of 2969 TRH tests) was analysed and the following causes identified: a) treated hyperthyroidism (38 after radioiodine, 5 after partial thyroidectomy, 5 after antithyroid drugs, 5 after radioiodine and partial thyroidectomy); b) simple goiter (7 without and 21 after partial thyroidectomy); c) autoimmune thyroiditis (27); d) other causes such as subacute thyroiditis (10); Riedel's thyroiditis (2), dyshormogenesis (2), drugs (6), treated toxic adenomas (2); e) etiology unknown or not identified (14).

Aged↗
PubMed1981

Echocardiographic features of the correctly functioning St. Jude Medical valve prosthesis.

The St. Jude Medical valve (SJM) is a new low-profile bileaflet prosthesis with central flow. We investigated 10 patients with aortic valve replacement and 11 with mitral valve replacement by means of combined echocardiography and phonocardiography. In patients with aortic valve replacement, echocardiography revealed during systole the anterior and posterior part of the ring together with both leaflets. During diastole, patients with mitral valve replacement showed part of the anterior leaflet and the entire posterior leaflet together with the posterior ring. Distinctive opening sounds were missing. In aortic prostheses, maximal opening followed S1 0.06 +/- 0.02 second. An amplitude of the posterior leaflet of 9.8 +/- 1.3 mm and a leaflet separation of 4.8 +/- 0.9 mm were measured. In mitral prostheses the maximal opening followed A2 0.10 +/- 0.02 second, the Q-closure interval was 0.07 +/- 0.03 second and leaflet separation was 4.4 +/- 0.8 mm. In both aortic and mitral positions, high values for opening and closing velocities were measured, and closing velocities exceeded opening rates. These findings establish the normal pattern and values in echocardiography and phonocardiography for patients with aortic valve replacement as well as mitral valve replacement with SJM prostheses.

Adult↗
PubMed1981

Lack of beta-adrenoreceptor hypersensitivity after abrupt withdrawal of long-term therapy with oxprenolol.

The possibility of beta-adrenoreceptor hypersensitivity after abrupt withdrawal of long-term therapy (8-18 months) with the slow-release (SR) formulation of oxprenolol (160-320 mg/day) was assessed in six patients with uncomplicated essential hypertension. The chronotropic dose 25 of isoproterenol (the dose that increases the resting heart rate by 25 beats/min), plasma concentration of catecholamines, triiodothyronin and thyroxin, plasma renin activity and aldosterone, hemoglobin, hematocrit and oxyhemoglobin dissociation were measured on the last day of oxprenolol SR intake and 1, 2, 3, 6 and 13 days after abrupt replacement by identical placebo tablets. The chronotropic dose 25 of isoproterenol (microgram/m2), which was greater than 25.6 in all patients on the last day of oxprenolol SR, fell to 4.83 +/- 2.03 on the second day and to 3.50 on the third day after its abrupt withdrawal and reached a minimal value on the thirteenth day (2.78 +/- 0.30). Throughout the study, plasma concentrations of catecholamines, triiodothyronin and thyroxin and oxyhemoglobin dissociation remained unchanged. Plasma renin activity and plasma aldosterone, which were suppressed during oxprenolol administration, rose significantly during placebo, coinciding with a significant fall in hematocrit and hemoglobin. No major subjective symptoms were reported by the patients. Thus, hypersensitivity of beta-adrenoreceptor-mediated responses was not demonstrated after sudden withdrawal of oxprenolol SR.

Adrenergic beta-Antagonists↗
PubMed1981

Effect of somatostatin on splanchnic hemodynamics in patients with cirrhosis of the liver and in normal subjects.

The effect of somatostatin on splanchnic hemodynamics was determined in 8 patients with cirrhosis of the liver and in 18 normal subjects using arterial-hepatic-venous catheterization. Estimated hepatic blood flow determined by indocyanine green infusion was 1.36 +/- 0.23 L/min (+/- SEM) in patients with cirrhosis and remained unaffected during 30 min of somatostatin (250 microgram/h) administration. Wedged hepatic venous pressure which was elevated to 23 +/- 1.8 mmHg was also uninfluenced. In contrast to somatostatin, an infusion of vasopressin (12 U/h for 30 min) given to the same patients, lowered estimated blood flow by 28% (p < 0.05) and wedged hepatic venous pressure by 18% (p < 0.02). Arterial gastrin and insulin levels were lowered during somatostatin infusion by 33% (p < 0.02) and by 75% (p < 0.005), respectively. In contrast to the cirrhosis, infusion of 250 microgram/h somatostatin into normal subjects was associated with a decrease of estimated hepatic blood flow from 1.20 +/- 0.16 to 0.88 +/- 0.12 L/min (p < 0.01) representing a 27% decline. Arterial gastrin and insulin concentrations were lower (p < 0.01) than in cirrhosis, but the basal levels were lowered by somatostatin to a similar degree in both groups of patients. A higher dose of somatostatin (500 microgram/h) administered to normal subjects resulted in a similar decrease of gastrin and of estimated hepatic blood flow as that seen with 250 microgram/h, whereas a lower dose (125 microgram/h) decreased gastrin but failed to influence estimated hepatic blood flow. Thus, somatostatin at a dose which has been used in the treatment of acute peptic ulcer hemorrhage (250 microgram/h) failed to influence estimated hepatic blood flow and wegded hepatic venous pressure in patients with cirrhosis but lowered splanchnic blood flow in normal subjects. Assuming that this effect contributes to somatostatin's therapeutic efficacy, these results cast doubt on its potential value in the treatment of upper gastrointestinal bleeding of cirrhotics with portal hypertension.

Dose-Response Relationship, Drug↗
PubMed1980

The effect of acebutolol on cardiac arrhythmias in patients with chronic coronary artery disease.

The effect of the beta-blocking drug acebutolol on the severity of cardiac arrhythmias and the incidence of exercise-induced arrhythmias was studied in 15 patients with chronic coronary artery disease using ambulatory Holter monitoring and bicycle ergometry. We found a significantly lower grading of arrhythmias both on long-term ECGs and during and after exercise. Furthermore, there was a significant decrease in the incidence of VPBs during and after exercise (18.15 +/- 7.7 on placebo vs. 3.46 +/- 1.7 on acebutolol). It is concluded that acebutolol favorably influences the incidence and severity of ventricular arrhythmias in patients with chronic coronary artery disease.

Acebutolol↗