Rapid Microbiology Screening in Pharmaceutical Workflows

Recently advances in miniaturization and automation have been utilized to rapidly decrease the time to result for microbiology testing in the clinic. These advances have been made due to the limitations of conventional culture-based microbiology methods, including agar plate and microbroth dilution, which have long turnaround times and require physicians to treat patients empirically with antibiotics before test results are available. Currently, there exist similar limitations in pharmaceutical sterility and bioburden testing, where the long turnaround times associated with standard microbiology testing drive costly inefficiencies in workflows. These include the time lag associated with sterility screening within drug production lines and the warehousing cost and time delays within supply chains during product testing. Herein, we demonstrate a proof-of-concept combination of a rapid microfluidic assay and an efficient cell filtration process that enables a path toward integrating rapid tests directly into pharmaceutical microbiological screening workflows. We demonstrate separation and detection of Escherichia coli directly captured and analyzed from a mammalian (i.e., CHO) cell culture with a 3.0 h incubation. The demonstration is performed using a membrane filtration module that is compatible with sampling from bioreactors, enabling in-line sampling and process monitoring.

Luteinizing hormone-releasing hormone agonist triptorelin antagonizes signal transduction and mitogenic activity of epidermal growth factor in human ovarian and endometrial cancer cell lines

This study was designed to elucidate the signal transduction mechanisms, mediating the antiproliferative effects of analogs of luteinizing hormone releasing hormone (LHRH) on cell lines derived from human cancers of the ovary (EFO-21, EFO-27) and the endometrium (HEC-1A, Ishikawa). The LHRH agonist triptorelin had no measurable effects on the activity of phospholipase C, protein kinase C, or adenylate cyclase in all 4 cell lines, though these enzymes could be activated through pharmacological stimuli. The proliferation of EFO-21, EFO-27 and HEC-1A cells in serum/phenol red-free medium was significantly stimulated by epidermal growth factor (EGF). This mitogenic effect of EGF was dose dependently antagonized by triptorelin, without affecting the concentrations of EGF receptors. Net tyrosine phosphorylation induced by 1 nM EGF was nearly completely suppressed by simultaneous addition of 10 mu M triptorelin or preincubation for 48 h with 100 nM triptorelin. This inhibitory effect of the LHRH agonist on EGF-induced net tyrosine phosphorylation was partly antagonized by exposure to 100 mu M sodium vandate, an inhibitor of phosphotyrosine phosphatase. In EFO-21, EFO-27, and HEC-1A cells exposure to 100 nM EGF for 5 min induced an approximately 5-fold increase in activity of mitogen activated protein kinase (MAP-kinase)/extracellular signal regulated kinase (ERK) which was virtually nullified, when the cells were exposed for 15 min to 10 mu M triptorelin. These data suggest that LHRH signal transduction mechanisms based on the activation of phospholipase C, protein kinase C, and adenylate cyclase, which operate in the pituitary gonadotroph, are not necessarily involved in the mediation of the antiproliferative effects of triptorelin in these ovarian and endometrial cancer cell lines. Instead our findings support the hypothesis that triptorelin interferes with mitogenic signal transduction, probably through antagonizing tyrosine kinase activity of the EGF receptor.

Systolic ventricular function in acute hypothyroidism: a study using Doppler echocardiography

The influence of thyroid state on left ventricular systolic function was studied in 11 patients (5 men, 6 women, aged 20-55 years) without cardiac disease, who had undergone total thyroidectomy and radioiodine treatment for thyroid cancer before. Pulsed-wave Doppler echocardiographic measuring of aortic blood flow and two-dimensional/time-motion (2D/M-mode) echocardiography were performed on two occasions once while the patients were mildly hyperthyroid on thyroxine replacement therapy and once when they were hypothyroid. During hypothyroidism left ventricular end-diastolic diameter decreased from 48 +/- 5 mm to 46 +/- 5 mm (p < 0.05). The diameter of the aortic ring, the left ventricular end-systolic diameter, the thickness of the interventricular septum and posterior wall, and fractional shortening did not differ significantly between the two studies. The following parameter of aortic blood flow changed significantly when passing from the hyperthyroid to the hypothyroid state: peak velocity (0.86 +/- 0.15 m/s versus 0.72 +/- 0.15 m/s, p < 0.01); mean velocity (0.49 +/- 0.08 m/s versus 0.44 +/- 0.08 m/s, p < 0.01); time- velocity integral (14.1 +/- 3.0 cm versus 12.3 +/- 3.1 cm, p < 0.05); stroke volume (43.0 +/- 9.7 ml versus 35.2 +/- 8.2 ml, p < 0.05); and preejection period (124 +/- 23 ms versus 147 +/- 21 ms, p < 0.01). Peak acceleration, mean acceleration, acceleration time and left ventricular ejection time did not change when the thyroid state was altered. It is concluded that left ventricular contractile function was not affected by acute hypothyroidism.(ABSTRACT TRUNCATED AT 250 WORDS)

Value of the proximal flow convergence method for quantification of the regurgitant volume in mitral regurgitation Influence of the mechanism of regurgitation, the imaging of the flow convergence region, and different calculation modalities

The purpose of this study was to evaluate whether the underlying mechanism of mitral regurgitation influences the reliability of the proximal flow con- vergence method to assess the regurgitant volume. Furthermore, the mode of imaging the flow convergence region and different correction algorithms for calculation of the regurgitant volume were compared.

METHODS

Regurgitant volume was assessed in 45 patients (age 61+/-13 years) with organic (n=19) and functional (n=26) mitral regurgitation by the proximal flow convergence method for aliasing velocities between 14 and 64 cm/s using two-dimensional color Doppler imaging. Different correction and calculation algorithms were compared. In addition, regurgitant volume was determined using color Doppler M-mode for an aliasing velocity of 28 cm/s. The quantitative Doppler method was used as reference.

RESULTS

In organic mitral regurgitation correlation coefficients (mean differences) between the proximal flow convergence method and the reference method were 0.25-0.43/ 0.58-0.67 (46-111 ml/15-17 ml) before/after geometric correction of the regurgitant volume for the aliasing velocities investigated. The correlation coefficient (mean difference) using color Doppler M-mode imaging was 0.68 (85 ml). The corresponding values in functional mitral regurgitation were 0.74-0.88/0.74-0.88 (-5-8 ml/-7-5 ml) for two-dimensional color Doppler and 0.88 (-1 ml) for M-mode imaging.

CONCLUSIONS

The regurgitant volume was overestimated by the proximal flow convergence method in organic mitral regurgitation irrespective of the application of different correction algorithms or the use of color Doppler M-mode. A sufficiently reliable determination of the regurgitant volume by the proximal flow convergence method was possible in functional mitral regurgitation. In that case a simplified calculation of the regurgitant volume based on the proximal flow convergence method was feasible.

[Comparison of efficacy, safety and cost-effectiveness of intravenous versus oral propafenone in paroxysmal atrial fibrillation]

The purpose of this study was to investigate the efficacy, safety and cost-effectiveness of intravenous and oral propafenone in the conversion of paroxysmal atrial fibrillation propafenone to sinus rhythm. We analysed two groups of 100 consecutive patients (pts) treated because of propafenone with duration < 48 h. The first group was treated with intravenous PFN (bolus of 70 to 140 mg) and the second group was treated with oral PFN (300 to 600 mg). These 2 groups were comparable in age, sex, evidence of CAD, hypertension, mitral valve disease, history of hyperthyroidism and the level of K+ at admittance. Conversion to sinus rhythm was achieved in 64 (64%) pts who received i.v. propafenone and in 77 (77%) who received oral propafenone (p < 0.05). We conclude that oral and intravenous propafenone is safe in the termination of propafenone. Oral route of administration appears to be superior to intravenous because of greater efficacy and cost-effectiveness.

Influence of the orifice inlet angle on the velocity profile across a flow convergence region by color Doppler in vitro

The converging flow field proximal to a leaking valve is determined among other things by the orifice inlet angle formed by the leaflets. Thus, the inlet angle affects the determination of regurgitant flow rate by the flow convergence method. Based on the hypothesis of spheric isovelocity surfaces, others had postulated that a local velocity within the flow convergence should change inversely proportional to changes in the three-dimensional inlet angle. This concept would allow correction of the determination of regurgitant flow for nonplanar orifice inlet angles. We tested this concept in vitro. In a flow model, the flow convergence region proximal to different orifice plates was imaged by color Doppler: funnel-shaped, planar and tip-shaped (inverted funnels) orifice plates, with circular orifices of 2- and 7-mm diameter. Velocity profiles across the flow convergence along the flow centerline were read from the color maps. As predicted, the local velocities were inversely related to the inlet angle, but only at the 2-mm funnel orifices, this effect was inversely proportional to the three-dimensional inlet angle (i.e., in agreement with the mentioned concept). However, for any 7-mm orifice and/or inlet angle of > 180 degrees, the effect of the inlet angle was considerably less than predicted by the aforementioned concept. With increasing orifice diameter and with decreasing distance to the orifice, the effect of the orifice inlet angle was reduced. The effect of the orifice inlet angle on the flow convergence region is modulated by orifice size and the distance to the orifice. Therefore, correction of flow estimates in proportion to the three-dimensional inlet angle will lead to considerable errors in most situations of clinical relevance, namely to massive overcorrection when analyzing velocities located close to wide orifices.

Experimental and theoretical 31P and 77Se nuclear magnetic shielding tensors for bis(dineopentoxyphosphorothioyl) diselenide

An intergrown crystal of two phases of bis(dineopentoxyphosphorothioyl) diselenide 1 was investigated by goniometer 31P NMR. From the angular dependence of the chemical shift, the tensors of a triclinic and a monoclinic phase were determined. The principal values sigma11, sigma22, and sigma33, of the absolute nuclear magnetic shielding tensors for the triclinic phase are 134.1, 227.2, and 375.5 ppm and for the monoclinic phase are 132.4, 227.8, and 374.2 ppm, respectively. In both cases, the principal axis 3 of the 31P tensor is directed nearly along the P=S bond and the principal axis 2 is nearly perpendicular to the S=P-Se plane. Calculations of the 31P and 77Se nuclear magnetic shielding tensors were performed for molecules of both phases of 1 and for model compounds by the sum-over-states density functional perturbation theory IGLO method. The rms distances between calculated and experimental 31P NMR icosahedral tensor values sigma(j) (j = 1, ..., 6) amount to 17-21 ppm. The calculated and experimental orientations of the 31P principal axes show a maximum difference of 5 degrees and rms distances of 3.2 and 3.3 degrees. For the principal value sigma33 of the selenium shielding tensor the agreement between calculated and experimental values is satisfactory, but the calculated values sigma11 and sigma22 are distinctly too small. Calculations for a model compound in which the methyl groups of the neopentoxy residue are substituted by protons lead practically to the same results.

Aortic regurgitant flow by color Doppler measurement of the local velocity 7 mm above the leak orifice--Part 2: Comparison with cardiac catheterization

AIMS

An in vitro study of the flow convergence region in aortic regurgitation has shown that regurgitant flow rate can be derived from the local velocity V(7 mm) at 7 mm distance above the leak orifice. This clinical study was performed to test this method in patients.

METHODS AND RESULTS

In 67 patients with aortic regurgitation, the flow convergence region was imaged by color Doppler. By analogy with the afore mentioned in vitro study, velocity profiles of the acceleration across the flow convergence region were read from the color maps. The profiles were fitted by using a multiplicative regression model. The V(7 mm) was read from the regression curve, and instantaneous regurgitant flow Q was derived from the V(7 mm) with the equation developed in vitro (Q = V(7 mm).cm2/0.28). Q showed a close association with the angiographic grade. Q-derived regurgitant stroke volume correlated significantly with invasive measurements by the angio-Fick method (r = 0.897, SEE = 19.9 ml, y = 0.88x + 5.9 ml).

CONCLUSIONS

Within the color Doppler flow convergence region of aortic regurgitation, the local velocity at 7 mm distance to the leak reflects regurgitant flow rate.

Experimental neonatal respiratory failure induced by lysophosphatidylcholine: effect of surfactant treatment

The purpose of this study was to characterize the toxic effects of lysophosphatidylcholine (lyso-PC) on neonatal lung function. Various doses of lyso-PC (from 0 to 40 mg/kg) were administered to near-term newborn rabbits. Lung-thorax compliance during mechanical ventilation was significantly decreased by doses >/=10 mg/kg, and static lung volumes during deflation were decreased by doses >/=20 mg/kg. Using the same experimental model, we investigated the effects of modified porcine surfactant (Curosurf, 200 mg/kg). Animals exposed to lyso-PC at birth and treated simultaneously with surfactant showed a satisfactory therapeutic response, whereas those treated after 30 min failed to respond. These animals also had a much larger leak of albumin into the air spaces and an elevated minimum surface tension of the lavage fluid in a pulsating bubble surfactometer, suggesting inactivation of the exogenous surfactant. Timing of surfactant administration may thus be essential for the therapeutic effect in this experimental model of acute lung injury.

Anisotropy of chemical shift and J coupling for P-31 and Se-77 in trimethyl and triphenyl phosphine selenides

The 31P and 77Se magic angle spinning (MAS) nuclear magnetic resonance (NMR) experiments for selenium-77 enriched (70%) trimethylphosphine selenide 1 and triphenylphosphine selenide 2 were carried out in order to determine the nuclear magnetic shielding tensors of both nuclei and to establish values of the phosphorus-selenium indirect spin-spin coupling anisotropy delta J. The m = +1/2 and m = -1/2 subspectra were analysed by the dipolar-splitting-ratio method of Eichele and Wasylischen. For the C(S) molecule 1, delta J was obtained to be +640 +/- 260 Hz from the 31P spectrum and +550 +/- 140 Hz from the 77Se spectrum. Density functional theory (DFT) calculations give a delta J value of about +705 Hz. The value of delta J could not be determined unambiguously by analysis of the 31P spectra for the C1 molecules 2; nevertheless, an estimation of delta J was possible. The principal axis 3 of the phosphorus shielding tensor was determined to be nearly parallel to the PSe bond in 1 and 2. For the selenium shielding of 1, the same orientation was found, whereas in 2, the principal axis 2 of the selenium shielding was found to be oriented nearly along the PSe bond. The experimentally determined phosphorus nuclear magnetic shielding tensors agree well with those calculated by the IGLO method. For those two principal values of the selenium-shielding tensors corresponding to directions nearly perpendicular to the SeP bond, the agreement between calculated and experimental values is satisfactory. For the third one, corresponding to the principal axis close to the SeP bond, the calculated deshielding contributions are distinctly too small for both compounds investigated. Trends observed for the calculated molecular orbital (MO) contributions to the shielding as well as possible reasons for the underestimation of the deshielding contributions along the SeP bond are discussed.

Quantification of mitral and tricuspid regurgitation by the proximal flow convergence method using two-dimensional colour Doppler and colour Doppler M-mode: influence of the mechanism of regurgitation

In patients with mitral (n=77: organic=49, functional=28) and tricuspid regurgitation (n=55: functional=54) quantified by angiography, the temporal variation of the proximal flow convergence region throughout systole was assessed by colour Doppler M-Mode, and peak and mean radius of the proximal isovelocity surface area for 28 cm/s blood flow velocity were measured. Additionally, the peak radius derived from two-dimensional colour Doppler was obtained. About 50% of the patients with mitral and tricuspid regurgitation showed a typical temporal variation of the flow convergence region related to the mechanism of regurgitation. The different proximal isovelocity surface area radii were similarly correlated to the angiographic grade in mitral and tricuspid regurgitation (rank correlation coefficients 0.55-0.89) and they differentiated mild to moderate (grade < or =II) from severe (grade > or =III) mitral and tricuspid regurgitation with comparable accuracy (82-96%). However, moderate mitral regurgitation due to leaflet prolapse in two patients was correctly classified by the mean M-mode radius and overestimated by both peak radii. Only half of the patients showed a typical variation of the flow convergence region related to the mechanism of regurgitation. The different proximal isovelocity surface area radii were suitable to quantify mitral and tricuspid regurgitation in most patients. However, in mitral regurgitation due to leaflet prolapse the use of the mean M-mode radius may avoid overestimation.

Comparison of the proximal flow convergence method and the jet area method for the assessment of the severity of tricuspid regurgitation

AIMS

To compare the value of the proximal flow convergence method and the jet area method for the determination of the severity of tricuspid regurgitation.

METHODS AND RESULTS

The proximal isovelocity surface area radius and the jet area/length were measured in 71 consecutive patients with angiographically graded (grade 0/I-III) tricuspid regurgitation. Rank correlation coefficients with the angiographic grade were 0.71 (P < 0.001) for the proximal isovelocity surface area radius (aliasing border of 28 cm.s-1), 0.66 (P < 0.001) for the jet area, and 0.63 (P < 0.001) for the jet length. The proximal isovelocity surface area radius was significantly correlated with the jet area/length (correlation coefficients 0.82/0.77, P < 0.001). Correct differentiation between mild to moderate (grade I-II) and severe (grade III) tricuspid regurgitation was achieved in 62 of 71 patients (87%) by means of the proximal isovelocity surface area radius, in 61 of 71 (86%) by the jet area, and in 62 of 71 (87%) by the jet length. Grade III tricuspid regurgitation was not identified in five of 21 patients (24%) by means of the proximal isovelocity surface area radius, in six of 21 (29%) by the jet area, and in seven of 21 (33%) by the jet length.

CONCLUSION

The flow convergence method and the jet area method are of similar value for the determination of the severity of tricuspid regurgitation. Both methods differentiated mild to moderate from severe tricuspid regurgitation in most patients. However, underestimation of severe tricuspid regurgitation in 20-30% of the cases represents a serious limitation of both methods.

Heart-rate variability for discrimination of different types of neuropathy in patients with insulin-dependent diabetes mellitus

It has been shown that patients with insulin-dependent diabetes mellitus (IDDM) may reveal abnormal alterations in heart-rate variability (HRV) due to autonomic neuropathy. This study was performed to prove whether heart-rate variability can be used to stratify diabetic patients with different types of neuropathy. 48 patients with IDDM (age 17-64 yr) underwent standard function tests to assess autonomic and peripheral neuropathy. According to the results of these tests they were divided into 4 groups: Group 1: 18 patients without autonomic or peripheral neuropathy. Group 2: 13 patients with peripheral neuropathy. Group 3: 7 patients with autonomic neuropathy. Group 4: 9 patients with autonomic and peripheral neuropathy. HRV was measured by continuous 24-hours monitoring and time domain parameters were calculated. The results were compared with sex and age-matched healthy controls according to the individual characteristics of the groups and among each subgroup. Our results showed that in Group 1 there was a significant difference of time domain parameters indicative of parasympathetic influence, i.e. rMSSD and pNN50 in comparison to the control subjects (p = 0.002, p = 0.008). These results depended on the duration of diabetes; a subgroup of patients with a duration of IDDM of less than 2 years had no significant differences of HRV values. Group 2 showed the same significant differences. Group 3 and 4 showed significant differences in all measured time domain variables (SDNN, SDANN, SDNN index, rMSSD and pNN50) in comparison to the control subjects (p < 0.04). A comparison of group 1 with group 2 offered significant differences in rMSSD and pNN50 (p = 0.004, p = 0.003). Comparing group 1 with group 3 and 4, all HRV parameters showed significant differences (p < 0.03). In conclusion, HRV is able to distinguish between patients with different types of neuropathy depending on the involvement of parasympathetic or more sympathetic influenced parameters. Furthermore, this method is able to unmask early manifestations of neurological disorders prior to their detection by neurological function tests.

Pathophysiology of neonatal lung injury induced by monoclonal antibody to surfactant protein B

Near-term newborn rabbits were exposed via the airways to a monoclonal antibody to surfactant protein B and ventilated for 0-120 min. Control animals received nonspecific rabbit or mouse immunoglobulin G, saline, or no material via the airways. Administration of the antibody at > or = 40 mg/kg elicited an immediate, significant fall in lung-thorax compliance associated with progressive intra-alveolar edema and/or alveolar collapse and necrosis and desquamation of airway epithelium, and hyaline membranes. The vascular-to-alveolar leak of human albumin and human immunoglobulin G, injected intravenously at birth and determined in lung lavage fluid 60-120 min after instillation of the antibody, was 1.8% for the left lung, with no difference between the markers. The average leak in control animals ventilated for 120 min was < 0.3% (P < 0.05). Cytospin preparations of lung lavage fluid from animals exposed to the antibody showed significantly increased recruitment of neutrophilic granulocytes. The pathology and pathophysiology of neonatal lung injury induced by the monoclonal antibody to surfactant protein B probably reflect a combination of direct inactivation of surfactant and an inflammatory response triggered by the immune reaction.

Signal-averaged electrocardiogram in patients with insulin-dependent (type 1) diabetes mellitus with and without diabetic neuropathy

The purpose of this study was to investigate the presence of ventricular late potentials derived from signal-averaged ECG in patients with IDDM with and without diabetic neuropathy. Eighty patients with IDDM but without evidence of cardiac disease and 80 age-matched healthy control subjects were investigated. The corrected QT interval was measured from the standard surface electrocardiogram. Ventricular late potentials were derived from signal-averaged electrocardiogram. Out of the 80 diabetic patients, 20 had an autonomic neuropathy, 20 had an isolated peripheral neuropathy, and 40 had no symptoms of neuropathy. The corrected QT interval was significantly prolonged in patients with an autonomic neuropathy as compared with the control group (436 +/- 23 ms(x 5) vs 384 +/- 23 ms(x 5), p < 0.001). In the other patient groups there was no significant prolongation of the corrected QT interval. Ventricular late potentials were present in 3 diabetic patients with an isolated peripheral neuropathy and in 1 control subject (NS). No diabetic patient with an autonomic neuropathy had ventricular late potentials. Our data did not indicate an increased incidence of ventricular late potentials derived from signal-averaged electrocardiogram in diabetic patients independent of a coexisting diabetic neuropathy or a prolonged corrected QT interval.

Influence of pulse repetition frequency and high pass filter on color Doppler maps of converging flow in vitro

Assessment of regurgitant flow by the flow convergence method is based on reading absolute velocities from color Doppler maps. Velocity overestimation by high pass filtering above 100 Hz has been reported. An extremely low filter, however, is impracticable in patients. A ratio of pulse repetition frequency (PRF)/filter of 10/1 usually results in good quality color maps as judged visually. We studied in vitro the influence of RPF and filter on the absolute velocities within color maps of the flow convergence, keeping PRF/filter at 10/1. The color maps were also compared with computerized flow simulations. Flow across different orifice plates was scanned using two different setups for each flow condition: low velocity setup (PRF 600-2500 Hz, filter 50-300 Hz) and high (PRF 1500-6000 Hz, filter 200-600 Hz). From the color maps, velocity profile curves were read along the flow center line across the flow convergence. The high velocity setup provided artefact-free color maps at a distance d = 2-4 through 8-11 mm to the orifice, the low setup at d = 6-8 through 18 mm. Within the overlapping range (d = 6-8 through 8-11 mm), the resulting curves showed no significant differences in local velocity, with a slight trend towards higher velocities with the high velocity setup (2.2-2.9%). The simulations agreed well with color Doppler except for slightly lower values at d > 10-12 mm. Changes in PRF and filter have no significant influence on the absolute velocities displayed within color maps as long as PRF/filter is kept close to 10/1.

[Unmasking an exclusively retrograde accessory pathway by catecholamines]

A 52-year-old man with frequent episodes of narrow QRS complex tachycardias with rates of 150/min was admitted for electrophysiological evaluation and treatment. P waves could be seen in the ST-segment of the surface ECG during tachycardia. Atrial stimulation during electrophysiological testing was not able to induce tachycardia. During atrial stimulation, there was no evidence of conduction via an accessory pathway or of dual AV node conduction properties. Ventricular stimulation showed complete ventriculoatrial block. After intravenous administration of the catecholamine orciprenaline, single atrial extrastimuli induced an AV macro-reentrant tachycardia with a rate of 165/min. VA conduction showed the earliest retrograde atrial activation in the left anterolateral area. Thus, there was an accessory pathway which only conducted in ventriculoatrial direction and only during adrenergic stimulation. After successful radiofrequency catheter ablation, complete ventriculoatrial block was recorded even after repeat administration of orciprenaline during ventricular stimulation. This case confirms the need to administer catecholamines in every undiagnosed tachycardia during electrophysiological testing to reveal the mechanism of the tachycardia.

Influence of the mechanism of regurgitation on the quantification of mitral regurgitation by the proximal flow convergence method and the jet area method

In 84 patients mitral regurgitation was quantified by angiography. The mechanism of regurgitation was determined by echocardiography (organic, n = 54, functional, n = 30). The radii of the proximal isovelocity surface areas in the flow convergence region for 28 and 41 cm.s-1 blood flow velocity and the area and length of the regurgitant jet were measured using colour flow Doppler imaging. The radii of the proximal isovelocity surface areas correlated more closely with the angiographic grade than the jet parameters irrespective of the mechanism of regurgitation. In more than 90% of the patients, grades I-II mitral regurgitation were correctly differentiated from grades III-IV by means of the radii of the proximal isovelocity surface areas. Using the jet parameters, the differentiation was correct in 50-90% of the patients depending on the mechanism of regurgitation. The jet area method particularly failed to identify grades III-IV organic mitral regurgitation due to a high prevalence of eccentric jets in these patients. It is concluded that the proximal flow convergence method was suitable for the quantification of mitral regurgitation irrespective of the mechanism of mitral regurgitation. On the other hand, the value of the jet area method depended largely on the regurgitation mechanism.

QRS morphologies of the surface ECG of nonsustained ventricular tachycardias during holter monitoring compared with QRS morphologies of spontaneous sustained ventricular tachycardias

The purpose of this study was to compare electrocardiographic (ECG) morphologies of nonsustained ventricular tachycardias (VTs) during Holter monitoring with the ECG morphology of documented, sustained, monomorphic VTs during the spontaneous event of tachycardia in 14 patients (9 with coronary artery disease), in whom a sustained, spontaneous monomorphic VT had been documented in a 12-lead ECG. All patients had a 24-hour Holter ECG without antiarrhythmic medication. Channel 1 of the Holter ECG was compared with leads V1, V2, and V3, and channel 2 with leads V4, V5, and V6. The Holter ECG of 10 patients in whom the QRS complex during sinus rhythm was similar to the QRS complex in the corresponding ECG leads was accepted for analysis. In 8 of the 10 patients, nonsustained VTs were detected during Holter monitoring. In one of these eight, the ECG morphology of at least one nonsustained VT in the Holter recordings was identical with the sustained VTs. Thus, incidences and ECG morphologies of nonsustained VTs during Holter monitoring do not correlate closely with those of spontaneous sustained monomorphic VTs. Therefore, most ventricular runs during Holter monitoring may have a mechanism different from that of spontaneous sustained VTs.

[Color Doppler echocardiography of the flow convergence region in vitro: effect of the orifice shape on proximal velocity profile]

The flow convergence method serves to determine flow across orifices (like valve leaks) by color Doppler. Both the PISA method (proximal isovelocity surface areas) and the PVP method (proximal velocity profile) were developed in vitro at circular orifice plates. Therefore, we studied the influence of a non-circular orifice shape on the color map of the flow convergence. Steady flow across orifices of the following shapes was imaged by color Doppler: Oval (6 x 2 mm), slit (12 x 1.5 mm), three-star (diameter 100, area 30 mm2), circular twin-orifice (two circular orifices diameter 2 mm at 10 mm distance from each other) and oval twin-orifice (two ovals 6 x 2 mm at 10 mm distance). As reference we imaged circular orifices with a similar opening area. The alias method was used to locate discrete velocities within the color map, and the proximal velocity profile along the flow center line was analyzed (mean of 24 subsequent images). The local velocity was plotted (y-axis) against its distance to the orifice (x-axis) providing proximal velocity profile curves. The more the orifice shape differed from circular, the more the proximal velocity profile was shifted downward: The profile proximal to the oval was not different from the reference profile proximal to the circular orifice. The profile proximal to the slit was considerably slowed, and proximal to the three-star was even slightly slower (local velocity -12 %, -23 % and -29 % at 14, 8 and 5 mm distance to the orifice). If the circular reference orifice corresponded to total flow across the twin-orifice, the proximal velocity profile of the latter was also shifted markedly downward (-20 %, -18 % and -23 % at 14, 8 and 5 mm distance to the circular twin-orifice). However, if the reference profile corresponded to flow across only one opening of the twin-orifice, the proximal velocity profile of the latter was shifted considerably upwards (+60 %, +71 % and +50 % at 14, 8, and 5 mm distance). Deviation of the orifice shape from circular leads to lower local velocities within the flow convergence; thus neglecting this orifice shape would result in underestimation of flow by the flow convergence method. However, presence of parallel neighboring flow increases the local velocities; neglecting this effect would lead to corresponding overestimation of flow.

[Three AV-nodal pathways in a patient with atypical AV-nodal reentry tachycardia]

In a female patient with paroxysmal AV nodal reentrant tachycardias the electrophysiological study revealed three AV nodal pathways. During atrial extrastimulation a sudden AH interval prolongation of more than 50 ms ("break" phenomenon) was observed twice at one basic cycle length. During ventricular extrastimulation a sudden prolongation of the AH interval of the anterograde AV nodal conduction of the induced echo beats was recorded. Three AV nodal pathways were thus present. The atypical form of AV nodal reentrant tachycardia was induced, showing a varying cycle length (290-340 ms). After radiofrequency catheter ablation of the fast conducting beta-pathway, another tachycardia was initiated, now showing a constant cycle length, using the two remaining, more slowly conducting alpha-pathways. One of these was eliminated in another ablation procedure.

Quantification of mitral regurgitation--comparison of the proximal flow convergence method and the jet area method

A total of 92 patients with mitral regurgitation (age 63 +/- 13 years, 51 men, 41 women), quantified by angiography, were studied using color-flow Doppler imaging of isovelocity surface areas in the flow convergence region proximal to the regurgitant orifice (PISAs) and of the regurgitant jet in the left atrium. The PISA radii for the flow velocities (aliasing borders) of 28 and 41 cm/s, jet area, jet length, and relation of jet area to left atrial area were measured. A proximal flow convergence region was imaged in 98% (85%) of all patients for a flow velocity of 28 (41) cm/s. A regurgitant jet could be visualized in all patients. The PISA radii for both flow velocities correlated more closely with the angiographic grade (rSp = 0.79 for both flow velocities) than the jet area (rSp = 0.43), jet length (rSp = 0.39), and relation of jet area to left atrial area (rSp = 0.37). A correct differentiation of grade I-II from grade III-IV mitral regurgitation was provided in 95% of the patients by the proximal flow convergence method for both flow velocities and in up to 78% of the patients by the jet area method using the uncorrected jet area. The PISA radii correlated weakly with the parameters from the regurgitant jet (r = 0.5-0.58). It can be concluded that the proximal flow convergence method and the jet area method reach comparable sensitivity for the detection of mitral regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)

[Assessment of severity of mitral insufficiency--value of various color Doppler echocardiographic methods]

A total of 79 patients with mitral regurgitation (age 62 +/- 11 years, 45 men, 34 women) quantified by angiography was studied using color-Doppler imaging of isovelocity surface areas in the flow convergence region proximal to the regurgitant orifice (PISAs), of the jet cross-section at the level of the regurgitant orifice and of the regurgitant jet in the left atrium. The PISA-radii for the flow velocities (aliasing borders) of 28 and 41 cm/s, the cross-sectional jet area and the jet length, and relation of jet area to left atrial area were measured. The sensitivity for the detection of mitral regurgitation was at least 97% for the color-Doppler methods investigated in these patients in which a sufficient imaging was obtained. However, a sufficient imaging of the flow convergence region and the jet cross-section was not possible in about 5% of all patients. The PISA-radii for both flow velocities and the cross-sectional jet area correlated more closely with the angiographic grade (rSp = 0.79-0.80, p < 0.001) than the jet area (rSp = 0.39, p < 0.001), jet length (rSp = 0.37, p < 0.001), and relation of jet area to left atrial area (rSp = 0.31, p < 0.01) did. A correct differentiation of grades I to II from grades III to IV mitral regurgitation was provided in 93-95% of patients by the proximal flow convergence and by the cross-sectional jet area method and, at most, in 76% of the patients by the jet area method using the uncorrected jet area.(ABSTRACT TRUNCATED AT 250 WORDS)

Doppler echocardiographic evaluation of left ventricular diastolic function in acute hypothyroidism

OBJECTIVE

Left ventricular diastolic dysfunction is an important cause of symptomatic heart failure. Previous studies suggest that thyroid dysfunction affects left ventricular diastolic function but the underlying mechanisms remain controversial. The study was undertaken to asses the influence of acute hypothyroidism on left ventricular diastolic function and to elucidate possible underlying mechanisms by means of Doppler echocardiography in a group of athyreotic patients, whose thyroid state depended only on external thyroid hormone supply and could therefore easily be controlled.

PATIENTS

Eleven patients (5 men, 6 women, aged 20-55 years), who had had total thyroidectomy, were investigated during mild hyperthyroidism and during acute hypothyroidism. Additionally, 11 healthy control subjects aged 25-51 years were included in the study.

DESIGN

M-mode echocardiography of the left ventricle and pulsed-wave Doppler echocardiography of the transmitral flow velocity pattern were carried out.

RESULTS

Acute hypothyroidism produced a decrease of left ventricular end-diastolic diameter from 48 +/- 5 to 46 +/- 5 mm (mean +/- SD P < 0.05), of peak velocity of early diastolic filling from 0.52 +/- 0.10 to 0.42 +/- 0.05 m/s (P < 0.05), of peak velocity of late diastolic filling from 0.42 +/- 0.10 to 0.36 +/- 0.09 m/s (P < 0.05), and a decreased time-velocity integral of early diastolic filling (6.2 +/- 1.8 vs 5.1 +/- 0.7 cm, P < 0.05). The other M-mode and Doppler echocardiographic parameters did not differ between the hyperthyroid and the hypothyroid states.

CONCLUSIONS

The observed changes of the trans-mitral flow velocity pattern during acute hypothyroidism can be attributed to a reduction of pre-load. There is no direct evidence that acute hypothyroidism affects the intrinsic diastolic properties of the left ventricle.

Quantification of mitral regurgitation by colour flow Doppler imaging--value of the 'proximal isovelocity surface area' method

In this study 97 patients with mitral regurgitation (age 62 +/- 11 years, 55 men, 42 women) quantified by angiography were studied using colour flow Doppler imaging of isovelocity surface areas in the flow convergence region proximal to the regurgitant orifice. The radii of the proximal isovelocity surface areas for the flow velocities of 28 and 41 cm/s were measured. A flow convergence region was imaged in 100% (96%) of the patients with Grade I/II or more and in 92% (64%) of the patients with Grade I mitral regurgitation for a flow velocity of 28 (41) cm/s. The radii of the proximal isovelocity surface areas correlated significantly with the angiographic grade in patients with sinus rhythm as well as atrial fibrillation. A correct differentiation of Grade I to II from Grade III to IV mitral regurgitation was provided in more than 90% of all patients for both flow velocities investigated. Assuming hemispheric proximal isovelocity surface areas, in 11 patients the regurgitant volumes from echocardiography (range: 2.6-241 (0.9-198) ml for a flow velocity = 28 (41) cm/s) correlated with, but considerably overestimated the values from cardiac catheterization (range: 1.4-72.5 ml) with r = 0.79 (0.82) (P < 0.01) and SEE = 57.9 (42.4) ml for a flow velocity of 28 (41) cm/s. It was concluded that colour flow Doppler imaging of the flow convergence region enables the diagnosis of mitral regurgitation and the differentiation between Grade I to II and Grade III to IV mitral regurgitation, but may be of little value in estimating the regurgitant volume, assuming a hemispheric symmetry of the proximal flow convergence region.

Color Doppler echocardiographic determination of mitral regurgitant flow from the proximal velocity profile of the flow convergence region

Flow rate across an orifice can be determined from color Doppler echocardiographic maps of the flow convergence region proximal to the orifice. Different methods have been developed in vitro. The proximal velocity profile method was prospectively evaluated in patients with mitral regurgitation. Color Doppler echocardiography was performed in 74 patients before cardiac catheterization. The increasing velocities within the flow convergence region were determined in an apical plane on the straight line from the transducer to the leak; thus the proximal velocity profile was established and plotted on a nomogram. Instantaneous regurgitant flow rate was derived from the position of the resulting curve in relation to the nomogram's reference curves, which were derived from in vitro measurements. Regurgitant stroke volume was calculated as regurgitant flow rate.regurgitant velocity-time integral/regurgitant peak velocity, using additional continuous-wave Doppler. The 55 patients with angiographic regurgitation had a close association between regurgitant flow rate (0 to 600 ml/s) and angiographic grade (Spearman's rank correlation coefficient = 0.91; p < 0.0001). Regurgitant flow rate did not overlap between grades < or = 2+, 3+ and 4+. In 16 patients, regurgitant stroke volume by echocardiography correlated well with that by the angiography/Fick method (r = 0.88; SEE = 17.1 ml), with a regression line close to identity (y = 0.89x + 12.7 ml). The proximal velocity profile method enables determination of mitral regurgitant flow and estimation of regurgitant volume.