Evaluation of left ventricular inflow and volume by MR

Considerable progress has been achieved during the past few years in the evaluation of intracardial blood flow by MR. Similar to ultrasound Doppler, it is possible now to registrate parameters of left ventricular diastolic filling as E/A ratio, velocity time integral of A- to E-wave (A(area)/E(area)), or isovolumetric relaxation time index. A total of 24 patients (7 women, 17 men, aged 24-69 yr) were examined, 5 of whom suffered from a hypertensive heart disease, 5 from a coronary heart disease, and 7 from mitral valve stenosis of various degree; 7 showed normal findings. E/A-ratio, A(area)/E(area), as well as isovolumetric relaxation time (IVRT) were evaluated by two different examiners on the same day by MR and ultrasound-Doppler, showing correlation factors of .89 for E/A ratio, .67 for A(area)/E(area), and .76 for IVRT in comparing both techniques. Additionally, to test the potential for making left ventricular function diagnoses from MR, time-volume curves for normal cases and patients with hypertrophic and dilated cardiomyopathy were elaborated by a computer-assisted 3D imaging technique. This technique showed good concordance with the results from cardiac catheterization or radionuclide ventriculography.

Assessment of cardiac adrenergic supply in mitral valve prolapse using m-[123I]iodobenzylguanidine scintigraphy

Presynaptic as well as postsynaptic adrenergic regulation abnormalities are reported in symptomatic patients with mitral valve prolapse. This study was undertaken to evaluate presynaptic sympathetic supply by m-[123I]iodobenzylguanidine scintigraphy in 17 preselected patients with mitral valve prolapse and symptoms suggestive of hyperadrenergic dysautonomia as compared to normal scintigraphic findings. Mitral valve prolapse was echocardiographically proven within the left parasternal long axis view. Percentual activity of m-[123I]iodobenzylguanidine in 33 sectors of all oblique slices along the short axis was calculated relative to the maximal uptake, set at 100%. In general, no significant differences of mean values of sectoral quantitative uptake of m-[123I]iodobenzylguanidine were detectable between patients and the control group. Only in two sectors of the basal anterolateral region P values < 0.01 were present. Thus, using m-[123I]iodobenzylguanidine scintigraphy as marker of cardiac adrenergic supply, no evidence of altered presynaptic hyperadrenergic supply was present in patients with mitral valve prolapse. These findings suggest postsynaptic regulation abnormalities to be preponderant in this condition.

Assessment of spatial and temporal velocity profiles distal of normally functioning Björk-Shiley prosthesis by the Doppler method

By Doppler echocardiography, the performance of heart valve prostheses is assessed with the aid of maximal transprosthetic velocities, which, however, may not be representative for the full spatial velocity profile in the vicinity of mechanical valve substitutes due to flow separation by the open occluder. The purpose of this study was to determine characteristics of velocity profiles downstream of a normally functioning Björk-Shiley prosthesis. In a pulsatile flow apparatus, different flow rates of 6.3 and 8.4 l/min were delivered. Using a spatially and temporally resolving ultrasonic Doppler method, velocity profiles 20 and 30 mm distal from the prosthesis were registered and displayed in a three-dimensional grid. The spatial velocity profile was found to deviate substantially from a flat profile at these transducer positions at the two flow conditions. Distal to the minor orifice, velocities measured only 70 and 80% of those downstream of the major orifice. In between, a region of relatively slow moving flow was present. The shape of the profiles remained essentially unchanged during acceleration and deceleration of flow. Thus, spatially resolved velocity profiles downstream of mechanical prostheses can be registered by an ultrasonic Doppler device. These findings may be useful for the detection of beginning malfunction both in the experimental and the clinical setting.

Ventricular performance in relation to heart rate and AV delay at rest

The influence of heart rate (HR) and AV delay (AVD) on left ventricular haemodynamics was studied in 12 patients classified as having coronary heart disease (CHD), hypertensive heart disease (HHD), dilated cardiomyopathy (DCM) or who served as controls. Using the conductance catheter technique, haemodynamics were measured during pacing rates of 80 to 180 beat.min-1 at AV delays of 0 to 240 ms. A 3-D linear regression analysis of the data quantified the influence of HR and AVD in principle for each group. An increase in HR resulted in a rise in the cardiac index without changing ejection fraction in the control group only, but led to a decrease in these parameters in HHD and DCM; cardiac index remained constant in CHD. CHD patients frequently had a more pronounced left ventricular end-diastolic pressure (LVEDP) elevation with higher HR, whereas left ventricular end-diastolic volume (LVEDV) and stroke volume decreased. In patients with HHD, lengthening of the AVD resulted in an increase in LVEDV and a decrease in LVEDP and left ventricular end-systolic volume (LVESV) leading to a higher ratio of stroke volume to LVEDP than in the other subsets. In DCM, longer AVD also resulted in a higher SV/LVEDP ratio, but in contrast to HHD the influence of AVD variation on LVEDP and therefore on the LVEDV/LVEDP ratio was missing.

Haemodynamic analysis of atrioventricular tachycardia

The aim of the study was to delineate the influence of the ventriculo-atrial interval (VAI) in tachycardia with regard to the underlying heart disease. Haemodynamic studies were performed by the conductance catheter technique during paced tachycardia with a HR of 140, 160 and 180 beat.min-1 at various VAI in 10 patients; three with coronary heart disease (CHD), three with hypertensive heart disease (HHD) and four serving as controls. The influence of the VAI accounted for an overall change in cardiac index (CI) of 30 +/- 14%. Alterations in left ventricular peak systolic pressure (LVPSP) depending on VAI were significantly higher (P < 0.01) in CHD patients (32 +/- 9%) than in other groups (14 +/- 9% in the controls and 17 +/- 8% in HHD patients). The influence of VAI on left ventricular end-diastolic pressure (LVEDP) did not differ between the subgroups and accounted for a mean overall change of 32 +/- 14%. Atrial activation during the last third of the cardiac cycle led to the highest values of CI, LVEDP and LVPSP in the control group, whereas in HHD and CHD groups minimal values of CI were correlated with maxima of LVEDP and LVPSP. Conversely, with atrial activation during the medium third of the cardiac cycle minima of CI and LVEDP were observed in the controls, whereas in HHD and CHD patients the highest cardiac index coincided with the lowest LVEDP. Thus tachycardias have different haemodynamic effects depending on the nature of myocardial impairment and the timing of AV coupling.

Cardiodynamic changes during passive tilt and acute nitrate therapy

In six patients with normal left ventricles and seven post-myocardial infarction patients cardiodynamic changes during tilt and acute nitrate medication were investigated. The conductance catheter was used for on-line registration of left ventricular volumes and a microtip manometer for high-fidelity pressure recordings. We analysed left ventricular end-diastolic volume index (EDVI) ejection fraction (EF), cardiac index (CI), heart rate (HR), end-systolic pressure (ESP) and end-diastolic pressure (EDP) in the supine position and 30 s after passive upright tilt. Supine and standing measurements were performed without medication and 2 min after acute nitrate medication (0.8 mg sublingual nitroglycerin). After unloading by upright tilt there was a similar reduction of average EDVI in the control group (-18 +/- 7 ml.m2) and in the post-infarction group (-21 +/- 18 ml.m2). The effect of nitroglycerin on EDVI (-12 +/- 4 ml.m2 control, -7 +/- 6 ml.m2 post-infarction) was less than the effect of upright tilt. EF in the control group improved by +8 +/- 5% (in absolute values) during passive tilt; the combined effect of tilt and nitrate was +12 +/- 6% EF (p < 0.05). In the post-infarction group EF did not change significantly during tilt and/or nitrate therapy. In the patients with normal regional ventricular function, CI during tilt was maintained at a constant level. In the post-infarction group the reduction in CI was not significant. Although the reduction in EDVI was similar in the control and infarction groups, the infarction group did not respond to the cardiodynamic change by increasing EF.(ABSTRACT TRUNCATED AT 250 WORDS)

[Rhabdomyolipoma of the right ventricle]

Echocardiography on a 29-year-old woman with exercise-unrelated tightness in the left chest for some months demonstrated an echo-dense space-occupying lesion in the outflow tract of the right ventricle (RV). Nuclear magnetic imaging revealed an ovular, fat-containing tumour, 3 x 2 x 2 cm in size. Because of threatened obstruction of the RV outflow tract removal of the tumour under cardiopulmonary bypass was undertaken. But complete removal was possible only by resecting a 2 x 3 cm area of the anterior wall of the RV, the resulting defect being covered with a Goretex patch. Histological examination identified the tumour as a rhabdomyolipoma. The patient was free of symptoms 1 year postoperatively.

Comparative investigation of the influence of nizatidine, ranitidine, and cimetidine on the steady-state pharmacokinetics of theophylline in COPD patients

The influence of usual regimens of the H2 blocking drugs, cimetidine, ranitidine, and nizatidine on the steady-state plasma concentrations and pharmacokinetic characteristics of theophylline was studied in seventeen patients with chronic obstructive pulmonary disease (COPD). Patients were dosed to steady-state with an oral, sustained-release formulation of theophylline given in therapeutic doses twice daily for 2 weeks. Over the next 4 weeks, each patient received a week-long regimen of each H2 blocker concomitantly with theophylline, and a week-long regimen of theophylline alone (control). At the end of each of the latter 4 weeks the steady-state pharmacokinetics of theophylline were assessed. Neither ranitidine nor nizatidine treatment altered the steady-state pharmacokinetics of theophylline relative to the control phase (i.e. no H2 blocker treatment). Values for theophylline C(ave), Cssmax, AUC0-12, and CLoral were significantly different during cimetidine treatment compared with all other treatments (ranitidine, nizatidine, and control). Cimetidine increased theophylline Cssmax, AUC0-12 and Cave by approximately 32%, and decreased theophylline oral clearance by approximately 23%. The authors conclude that cimetidine alters the steady-state pharmacokinetics of theophylline in COPD patients, whereas ranitidine and nizatidine are without effect.

[Rate of success and restenosis of PTCA in patients over 75 years of age]

In 82 patients (pts), ages 75-90 years (52 m, 30 f; mean age 77 +/- 3 years) with mainly unstable angina (59 pts) or acute myocardial infarction (7 pts) a PTCA or recanalization was attempted. Successful PTCA was achieved in 57 of 69 pts (83%); occlusions could be reopened in all six pts with myocardial infarction and totally occluded infarct related artery, and in three of seven pts with stable or unstable angina pectoris. The primary success rate of PTCA alone in pts with unstable angina was 81%, and improved to 92% in pts with stable angina. Sixteen procedures were multiple vessel and six were multiple lesion PTCA, so that the lesion-related success rate of PTCA was higher (87%). One patient died in connection with the procedure (procedure related-mortality 1.2%), two pts underwent myocardial infarction (2.4%), one patient emergency bypass grafting (1.2%). The in-hospital mortality was 4.9% and concerned exclusively patients with unstable angina and unsuccessful procedure. Local complications at the puncture site occurred in two patients. The angiographic restenosis rate of PTCA was 58% (44% in patients with stable and 63% in patients with unstable angina pectoris). Seventeen patients with 19 restenoses had successful repeat PTCA; reintervention failed in two patients. We conclude that PTCA can be performed in patients of old age with a resulting comparable primary success rate as in younger patients. Complications seem to be more frequent. The restenosis rate is higher, but with regard to stable and unstable angina, not significantly so. The prognosis in patients with unstable angina and unsuccessful procedure is apparently unfavorable.

In vivo evidence that ethosuximide is a substrate for cytochrome P450IIIA

The role of various subfamilies of rat hepatic cytochrome P450 in the oxidation of ethosuximide was evaluated by comparing ethosuximide clearance in control rats and those pretreated with relatively selective P450 inducers and/or inhibitors. Clotrimazole pretreatment increased ethosuximide clearance threefold (p less than 0.005). Dexamethasone increased ethosuximide clearance twofold (p less than 0.001), and the dexamethasone effect was completely abolished by a single dose of triacetyloleandomycin. These results suggest a prominent role for cytochrome P450IIIA in ethosuximide metabolism in the rat. Isoniazid increased ethosuximide clearance twofold (p less than 0.001), and this effect was abolished by a single dose of diallylsulfide, suggesting that ethosuximide is also processed by cytochrome P450IIE1 in rats. Phenobarbital pretreatment increased ethosuximide clearance 2-2.7 fold (p less than 0.001); an effect that was only partially reversed by orphenadrine, an inhibitor of cytochrome P450IIB/IIC enzymes. This suggests a quantitatively less important role for the IIB/IIC subfamilies in processing ethosuximide, since phenobarbital is an inducer of P450 subfamilies IIB, IIC, IIE, and IIIA. Neither the cytochrome P450IA inducer, beta-naphthoflavone, nor the inhibitor, alpha-naphthoflavone altered ethosuximide clearance. Ajmaline, an inhibitor of cytochrome P450IID, had no effect on ethosuximide clearance. Together, these findings suggest that ethosuximide is principally oxidized by cytochrome P450IIIA, and that cytochrome P450IIE may play an important role. Cytochromes P450IIB/C play less prominent roles in ethosuximide oxidation, and neither cytochrome P450IA nor cytochrome P450IID is involved.

Hypertrophic obstructive cardiomyopathy as a manifestation of a cardiocutaneous syndrome (Noonan syndrome)

The case of a 50-year-old patient with hypertrophic obstructive cardiomyopathy is reported. The patient demonstrated somatic signs of the Turner phenotype, but a cytogenetically normal karyotype was shown. These findings were compatible with the diagnosis of Noonan syndrome. The most commonly diagnosed cardiac disease in this syndrome is pulmonary stenosis, followed by hypertrophic cardiomyopathy. The patient's prognosis is limited by the natural history or the typical complications of the underlying cardiac lesion.

[Magnetocardiography. Biomagnetic localization of impulse development and transmission of the heart]

Magnetocardiography is a non-invasive biomagnetic technique for measuring magnetic fields produced at the surface of the body when the heart is stimulated to beat. The measurement is contact-free and is independent of tissue resistance. For the first time, magnetocardiography employing multi-channel systems permits the accurate, non-invasive localization of accessory conduction pathways and ectopic ventricular activity.

Congenital myocardial sympathetic dysinnervation (CMSD)--a structural defect of idiopathic long QT syndrome

Concerning the pathogenetic mechanism of idiopathic long QT syndrome (LQTS), the hypothesis of a specific sympathetic imbalance has gained general acceptance, but its validity has never been proven. To test this hypothesis I-123-MIBG, an analogue of norepinephrine and guanethidine, was used to provide scintigraphic display of the efferent cardiac sympathetic innervation. Twelve members of four LQTS families (mean age 38.2 +/- 17.2 years, eight males) and eight healthy volunteers (mean age 48.2 +/- 13.3 years, five males) were studied by means of I-123-MIBG single photon emission computed tomography (SPECT). A quantitative analysis of all scans was performed. All scans of the healthy volunteers show a uniform tracer uptake with sometimes slightly decreased activity in the apex. (1) All patients with QTc greater than 440 msec (n = 5); (2) all, who had suffered from at least one episode of torsade de pointes, ventricular fibrillation (VF) or syncope (n = 5); and (3) all symptomatic patients with QTc prolongation (n = 4) have reduced or abolished (P less than 0.02) MIBG uptakes in the inferior and inferior septal parts of the left ventricle (congenital myocardial sympathetic dysinnervation [CMSD]). Additionally, one female without symptoms or QTc prolongation (LQT) shows an abnormal MIBG SPECT similar to the one of her daughter, who has LQT and symptoms. One male without LQT, who had suffered from VF shows CMSD similar to his father, who has LQT, but no symptoms. All members of the families with normal MIBG SPECTs have neither LQT nor symptoms. In all families CMSD fulfills the criteria of autosomal-dominant inheritance. Normal QTc-interval predicted only in 57% normal cardiac sympathetic innervation in the present LQTS families. Therefore, quantitative I-123-MIBG SPECT enables to identify myocardial sympathetic dysinnervation as structural defect in LQTS. CMSD is associated with and without LQT and presents a pattern of autosomal-dominant inheritance. LQT at rest or during exercise was specific (100%), but less sensitive (63%) in the assessment of CMSD than I-123-MIBG SPECT.

Biomagnetic localization of ventricular arrhythmias

The magnetic fields caused by electrical activity of the human heart can be coherently measured with a highly sensitive, multichannel, superconducting quantum interference-device system and can enable noninvasive localization of the underlying electrical activity. The magnetocardiograms (MCGs) of 10 patients with spontaneous premature ventricular complexes (PVCs), three patients with ventricular tachycardia (VT), and four healthy subjects with induced paced beats were recorded for 2-15 minutes. After correction for superimposed repolarization activity, the site of origin of the arrhythmias was localized from the magnetic field distribution at the onset of the ectopic beats. The localization results of paced beats showed an error of a few millimeters in relation to the position of the catheter tip. The results of spontaneous PVC and VT were confirmed with endocardial mapping or associated with ischemic lesions. The authors conclude that multichannel magnetocardiographic studies enable the completely noninvasive localization of ventricular arrhythmias.

Clinical magnetocardiography: experience with a biomagnetic multichannel system

The magnetic fields caused by the human heart's electrical activity were coherently recorded with a biomagnetic multichannel system (KRENIKON) during 1 to 10 minutes in 49 patients. 31 to 37 magnetic channels were recorded simultaneously with the ECG and respiration. Comparison of a magnetic index and the Sokolow-Lyon index to echocardiographic findings in the quantification of left ventricular hypertrophy demonstrated the superiority of the magnetocardiogram (MCG) as compared to the ECG. The magnetocardiographic investigation of patients with WPW-Syndrome, ventricular extrasystoles, ventricular tachycardia, and paced ventricular beats demonstrated that multichannel magnetocardiography permits the non-invasive three dimensional localization of arrhythmogenic tissue with high spatial accuracy.

[Magnetic resonance rheography in comparison to Doppler ultrasonography in the assessment of mitral valve stenosis]

Ultrasound-Doppler-technique and heart catheterization today are used routinely for the evaluation and graduation of mitral valve stenosis. A new magnetic resonance-technique of intracardial blood-flow registration now allows the grading of mitral valve stenosis. Good reliability and practicability of the demonstrated method in comparison with the ultrasound-Doppler-technique is shown. Future development of an alternative, completing magnetic-resonance method for the evaluation of valvular heart disease and shunt diagnosis is expected.

[Localized 31 phosphorus NMR spectroscopy of the human heart--development of a measuring method and initial clinical application]

In this work, the technique of 31P-NMR-spectroscopy is applied for the first time to diagnose coronary heart disease in patients, using a suitable measuring technique. In 13 healthy volunteers we applied a method comfortable and tolerable for patients, which enabled us to examine the myocardium inside the reception area of a surface coil. Concerning myocardium-specific selectivity and sensitivity the localization techniques FROGS (Fast-ROtating-Gradient-Spectroscopy), 1-D-ISIS (1-Dimensional-Image-Selected-In-vivo-Spectroscopy) and 3-D-ISIS were compared. By a combination of the 3-D-ISIS-technique with magnetic resonance imaging, we obtained a monitored position of the volume of interest (VOI) within the myocardium, thus gaining a selective measurement. The cube-shaped VOI with a lateral length of 50 mm was placed into the apical-septal area of the myocardium. On the basis of the obtained results, we examined seven patients suffering from coronary heart disease, which was symptomatic and verified by coronary angiography. The 31P-NMR-spectra of the two examined groups were computed into numbers representing the relative content of the myocardial high-energy-phosphates. In addition, the quotients PCr/ATP and Pi/ATP were calculated and compared. With this small number of cases the evaluation of the PCr/ATP-ratios already showed a significant difference of 0.34 (p less than 0.01) between patients with coronary heart disease (0.49 +/- 0.19) and healthy volunteers (0.83 +/- 0.27). The findings suggest the conclusion that 31P-NMR-spectroscopy is able to be instrumental in the diagnostic detection assessment of the metabolic state in coronary heart disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronotherapy in coronary heart disease: comparison of two nitrate treatments

The purpose of this study was to assess the ischemic burden and the hemodynamic changes during daily activities in patients with coronary heart disease. Three exercise tests were performed during the day (10:00 a.m., 2:00 p.m., 6:00 p.m.), recording ST-segment depression, pulmonary artery pressure, pulmonary wedge pressure, and cardiac output as well as heart rate and systemic blood pressure during placebo and nitrate therapy. With placebo as well as nitrate therapy there was a gradual increase of ischemia and preload and a decrease of cardiac output during the day. High nitrate concentrations led to a significant reduction of both preload and ST depression with a marked circadian phase dependency of cardiovascular effects.

Changes in the steady-state pharmacokinetics of theophylline during treatment with dirithromycin

The steady-state plasma concentrations and pharmacokinetic characteristics of theophylline were studied during intermittent treatment with dirithromycin. The addition of dirithromycin (500 mg orally once daily at 7:00 AM) to a sustained-release theophylline dosing regimen (200 mg every 12 hours) elicited small changes in the steady-state pharmacokinetics of theophylline. Mean steady-state plasma theophylline trough concentrations (Cmin) were invariant before, during, and after dirithromycin treatment; however, mean average steady-state plasma theophylline concentrations (Cav) declined by 18% during dirithromycin treatment (P less than .05), and mean peak plasma concentrations (Css,max) declined by 26% (P less than .01). Theophylline clearance (CL/F) exhibited an increase of comparable magnitude during dirithromycin treatment, although the increase in CL/F was not statistically significant (.05 less than P less than .1). Dirithromycin treatment alters the steady-state pharmacokinetics of theophylline; however, the magnitude of the changes is small and is not likely to modify treatment outcomes.

[The computer simulation of orthodontic tooth movements]

A personal computer programme is presented which allows the prediction of orthodontic tooth movement under the influence of any given force and moment. The changes in position of the front teeth caused by the chosen forces appear on the monitor as a three-dimensional diagram and as a movie-like picture sequence.