[Atrial myxoma in the patients of a general and internal medicine outpatient clinic]. / Das Vorhofmyxom bei Patienten in einer allgemein-internistischen Ambulanz.

In a medical out-patient clinic, over a period of several years, atrial myxoma was diagnosed in four patients with ages ranging between 32 and 69 years. With the exception of one patient referred for assessment of ventricular premature beats, presentation was not primarily attributable to cardiac causes. In all patients, there was a latency period of years between the onset of symptoms and establishment of the diagnosis. The history of patients with atrial myxoma includes symptoms such as dizziness, syncope, transient cerebral ischemia, weight loss and malaise. The differential diagnosis may encompass consideration of neoplastic disease since laboratory findings can reveal evidence of an inflammatory reaction, accelerated sedimentation rate, anemia, abnormal electrophoresis, hypoproteinemia as well as elevated alkaline phosphatase. One patient had undergone numerous examinations to rule out the presence of malignant disease. Symptoms related to the cardiovascular system include exertional dyspnea, premature beats, tachyarrhythmias and nonspecific chest pain. Auscultatory findings are consistent with those of mitral stenosis. M-mode and two-dimensional echocardiography established the diagnosis in all patients and confirmed the usefullness of this examination technique in the assessment of patients in a general medical clinic.

[Occurrence of HLA-antigens in patients with hypertrophic cardiomyopathy]. / HLA-Antigen-Häufigkeiten bei Patienten mit hypertrophischer Kardiomyopathie.

The etiology of hypertrophic cardiomyopathy with (HOCM) and without obstruction (HCM) is poorly understood. Controversial data have been published concerning the association of HLA-B-12-antigen with HOCM and HCM respectively. Further, HLA-D-antigen occurrence has been determined in few patients with HOCM or HCM. In 29 patients with HOCM, 38 patients with HCM, and matched healthy persons we determined the occurrence of HLA-A, B, C and DRW-antigen using the test of microcytotoxicity in lymphocytes. HLA-antigens occurred with similar frequency in patients with HOCM and HCM and in control subjects. 25% of the patients and 23% of the control subjects had HLA-B-12. Further, no difference was detected in the frequency of occurrence of HLA-antigens in patients with HOCM and in patients with HCM. The data support the view that HLA tissue typing is of no diagnostic value in identifying patients with HOCM or HCM.

Inactivation of contraction as a determinant of the length-active tension relation in heart muscle of the cat.

In isometrically contracting isolated cat papillary muscles, the mechanism determining the reduction in active tension (P) at lengths (L) below the optimal length (Lmax) for maximal tension development (Pmax) was studied. Increasing [Ca2+] from 1.25 to 5 mM, paired electrical stimulation and caffeine augmented P-O/max by 77,61 and 23% respectively, as well as the tension developed at any given length on the ascending limb of the length-active tension relation. To see whether below Lmax the degree of activation is dependent on length, these length-active tension relations were expressed as P/Pmax relative to L/Lmax where Pmax and Lmax in each inotropic state was 100%. These normalized length-active tension relations were not altered by different [Ca2+]o, but shifted upward and to the left by caffeine and paired stimulation. The effects of elevating [Ca2+] on the length-active tension relation suggests that restoring forces and fixed internal loads are not an important factor in decreasing active tension at short lengths. The effects of caffeine and paired stimulation support the view that in cardiac muscle inactivitation of contraction is a major factor determining the fall in active tension at decreasing length.

Time course of mechanical activity in mammalian cardiac muscle: dependence on species, loading, and displacement.

We have found that animal species is of great importance when mechanics of contraction are analyzed in mammalian cardiac muscle. Mechanics of contraction have been studied comparatively in the isolated papillary muscles of the rat, cat, and rabbit under control conditions and following alterations of loading and inotropic interventions. The time course of the shortening ability measured in terms of the velocity of shortening at constant contractile element length and load following quick releases to preload peaked at 20, 30, and 70% of time to peak force (TPF) in the rat, cat, and rabbit, respectively, and declined more slowly in the rabbit. The shortening ability peaked progressively later in contraction at increasing loads in the cat, but not in the rabbit. Shortening ability measured after releases to zero load or after imposing "load clamps" of variable magnitude and duration reached the maximum much later in the rabbit than in the cat. The contractile response to changes of the contraction mode from isometric to isotonic was different in cat and rabbit. Upon increase in the stimulation rate from 6 to 60/min, force increased to a greater extent in the rabbit than in the cat, while TPF did not decrease in the rabbit as seen in the cat. Caffeine (10mM) increased developed force more in the rabbit than in the cat, while even 1 mM caffeine decreased force in the rat. The onset of the shortening ability was greatly delayed by caffeine in the cat and rat but not in the rabbit. Afterloaded force-peak velocity relations were curvilinear in the cat and rat; these relations approached linearity in the rabbit in the control state, and in both cat and rabbit in the presence of caffeine. The differences in the mechanics of contraction, in the contractile response to alterations in loading, and to caffeine in the ventricular muscle of the rat, cat, and rabbit are viewed as indicators of differences in excitation-contraction coupling of ventricular cardiac muscle from these different mammalian species.

Mechanical activity of mammalian heart muscle: variable onset, species differences, and the effect of caffeine.

The time course of the ability to shorten during contraction was measured using velocity of shortening of the contractile element corrected for length after quick releases to constant loads, in isolated papillary muscles of the cat, rabbit, dog, and rat. The ratios of time-to-peak shortening ability at preload (TTPA), to time-to-peak active force (TPF), were 0.30, 0.36, 0.32, and 0.70 in the cat, dog, rat and rabbit, respectively. When the pacing rate was increased from 12 to 60/min, peak force was augmented in the cat (36%) and rabbit (108%), while TPF decreased in the cat (by 30%) but not in the rabbit. Various inotropic interventions did not alter the ratio of TTPA/TPF in any species. However, caffeine (10mM) increased this ratio to that normally found in the rabbit, in which it was not altered. Afterloaded force-peak velocity relations of the cat, dog, and rat were curvilinear, but in the rabbit in the control state, and in the cat and dog in the presence of caffeine, these relationships tended to be linear. The differences in the time course of the ability to shorten among these mammalian species may be related to differences in excitation-contraction coupling.