Immature ovarian teratoma in a 20-year-old woman: A case report

Immature ovarian teratomas are a rare subtype of germ cell tumours characterized by the presence of embryonic elements, particularly primitive neuroepithelium, and they typically affect young women. We report the case of a 20-year-old woman who presented with a growing abdominal mass that turned out to be a grade II immature teratoma after adnexectomy. This article reviews the clinical presentation, imaging features, and some of the main problems that arise in the management of immature ovarian teratomas.

[Recurrent acute fatty liver of pregnancy: About a case and a review of the literature]

Acute fatty liver of pregnancy (AFLP) is a specific but rare hepatopathy that can usually complicate the third trimester of pregnancy. It is potentially fatal for the mother and the fetus. To our knowledge, only eight cases of recurrence have been published, we report a new case. The first episode presented by our 23-year-old patient was suspected in front of a cutaneous-mucosal jaundice with vomiting occurring on pregnancy of 35weeks of gestation (WG). Hyperleucytosis, abnormalities of the hepatic balance, as well as a hypoglycemia were biological elements supporting the diagnostic beam. On the other hand, medical imaging could not bring a clear confirmation. The evolution was favorable after deferred delivery by caesarean section for pulmonary maturation. Three years later, she presented to the obstetrical emergency room at 36weeks and six days of gestation, with a clinical and biological picture almost similar to that of the first episode. A caesarean section was then indicated for suspicion of recurrence. The evolution is favorable for the mother and her children. The interest of the communication on the risk of recurrence, the clinical and biological monitoring in particular in the third trimester of the subsequent pregnancy are imperative, in order to improve the prognosis of this pathology.

Measurement of Apparent Diffusion Coefficient (ADC) Values of Ependymoma and Medulloblastoma Tumors: a Patient-based Study

Background:

Some brain tumors such as ependymoma and Medulloblastoma have similar MR images which may result to undifferentiated them from each other.

Objective:

This study aimed to compare the apparent diffusion coefficient (ADC) of two different cerebellar pediatric tumors, including ependymoma and medulloblastoma which have shown similar clinical images in conventional magnetic resonance imaging (MRI) methods.

Material and Methods:

In this analytical study, thirty six pediatric patients who were suspected to have the mentioned tumors according to their CT image findings were included in this study. The patients were subjected to conventional MRI protocols followed by diffusion weighted imaging (DWI) and ADC values of the tumors were calculated automatically using MRI scanner software.

Results:

The mean (± SD) ADC value for ependymoma (1.2± 0.06 ×10^-3 mm²/s) was significantly higher than medulloblastoma (0.87 ± 0.02 ×10^-3 mm²/s) (p = 0.041). Moreover, the maximum ADC value of ependymoma was considerably different in comparison with medulloblastoma (1.4 ×10^-3 mm²/s and 0.96×10^-3 mm²/s, respectively; p = 0.035). Furthermore, the minimum ADC value of ependymoma was higher compared to medulloblastoma (1.0 ×10^-3 mm²/s and 0.61×10^-3 mm²/s, respectively), but there was not significant (p = 0.067).

Conclusion:

Evaluation of ADC values for ependymoma and medulloblastoma is a reliable method to differentiate these two malignancies. This is due to different ADC values reflected during the evaluation.

Synchronization behavior in a ternary phase model

Localized traveling-wave solutions to a nonlinear Schrödinger equation were recently shown to be a consequence of Fourier mode synchronization. The reduced dynamics describing mode interaction take the form of a phase model with novel ternary coupling. We analyze this model in the presence of quenched disorder and explore transitions to partial and complete synchronization. For both Gaussian and uniform disorder, first-order transitions with hysteresis are observed. These results are compared with the phenomenology of the Kuramoto model which exhibits starkly different behavior. An infinite-oscillator limit of the model is derived and solved to provide theoretical predictions for the observed transitions. Treatment of the nonlocal ternary coupling in this limit sheds some light on the model's novel structure.

HER2 Expression Status and Prognostic, Diagnostic, and Demographic Properties of Patients with Gastric Cancer: a Single Center Cohort Study from Iran

Background: The fourth most prevalent cancer worldwide and a major cause of death in developing countries is gastric cancer (GC). Human epidermal growth factor receptor 2 (HER2), is a proto-oncogene expressed in different solid tumors. This study aimed to evaluate possible associations of HER2 expression status with survival rate, age, sex, tumor grade, histopathological type, and primary tumor location in patients with GC. Methods: Subjects were enrolled in this cohort study after consideration of inclusion and exclusion criteria. Biopsy specimens were stained using immunohistochemistry. Samples with a score of 3+ were considered to exhibit HER2 overexpression. The mentioned variables were extracted from patients’ files as well as by clinical evaluation. The Kaplan-Meier method was applied for analyzing the survival rate and Chi square for possible factor associations. Results: A total of 210 patients (25.2% female and 74.8% male) were enrolled. In a 5-year follow-up (adherence rate: 45.7%), the average survival was 9.4±10.9 months. HER2 overexpression was evident in 24%. There was no statistically significant association found between HER2 expression and primary tumor location (p-value=0.63), histopathological type (p-value=0.72), or tumor grade (p-value=0.051). Furthermore, no statistically significant links were apparent with tumor grade in either male or female groups as well as patients aged ≥60 and ˂60 years (all p-values >0.05). Moreover, no statistically significant association was detected between HER2 expression status (p-value=0.88), sex (p-value=0.31), and age (p-value=0.055) with patient survival. Conclusions: No statistically meaningful association was found between all parameters examined and HER2 expression status. Divergence of the results from earlier studies might be due to genetic variation. Thus, performing a meta-analysis on certain races might be helpful for clarification.

Adaptive control with state-dependent modeling of patient impairment for robotic movement therapy

This paper presents an adaptive control approach for robotic movement therapy that learns a state-dependent model of patient impairment. Unlike previous work, this approach uses an unstructured inertial model that depends on both the position and direction of the desired motion in the robot's workspace. This method learns a patient impairment model that accounts for movement specific disability in neuro-muscular output (such as flexion vs. extension and slow vs. dynamic tasks). Combined with assist-as-needed force decay, this approach may promote further patient engagement and participation. Using the robotic therapy device, FINGER (Finger Individuating Grasp Exercise Robot), several experiments are presented to demonstrate the ability of the adaptive control to learn state-dependent abilities.

Evaluation of Mangled Extremity Severity Score (MESS) as a predictor of lower limb amputation in children with trauma

BACKGROUND

Management of the severely injured lower limb in children remains a challenge despite advances in surgical techniques. Models that predict the risk of lower limb trauma patients are designed to provide an estimation of the probability of limb salvage. In this study, we validate Mangled Extremity Syndrome Index (Mangled Extremity Severity Score [MESS]) by measurement of its discrimination in children.

MATERIALS AND METHODS

From September 2009 to 2010, we collected the hospital records of all children who presented with lower extremity long bone open fractures. The inclusion criteria were I grade, II B, III C open fractures, severe injury to three of four organ systems, and severe injury to two of four organ systems with minor injury to two of four systems that require surgical interventions. Severity of limb injury was measured using MESS. Patients were followed up for 1 year. The discrimination of MESS model in differentiating of outcome in patients was assessed by calculating the area under the receiver operator characteristic plot.

RESULTS

We evaluated 200 children referred consecutively to our center. The mean MESS in the amputation group was 7.5 ± 1.59 versus 6.4 ± 2.02 in the limb salvage group (p = 0.04). Amputation rate was 7.5% (n = 15). Percentages of skeletal/soft-tissue injury was different between groups (p = 0.0001). Children in the amputation group showed more tissue injury compared with limb salvage group. The best clinical discriminator power was calculated as MESS ≥ 6.5 (sensitivity = 73%, specificity = 54%).

CONCLUSION

We assumed that patients with a high risk of amputation can be identified early, and specific measures can be implemented immediately by using MESS with threshold of 6.5.

First Report of Citrus viroid V in Moro Blood Sweet Orange in Iran

Viroids are nonencapsidated, small, circular, single-stranded RNAs that replicate autonomously when inoculated in their host plants in which they may elicit diseases (sensitive hosts) or replicate as latent infections (tolerant hosts). Citrus viroid V (CVd-V) was initially identified in Spain (1) and later found to be present in the United States, Nepal, and the Sultanate of Oman (2). CVd-V is a member of the Apscaviroid genus within the Pospiviroidae family. Like other members of this genus, CVd-V has a restricted host range but it is able to infect a wide range of citrus and citrus related species (1,2). Within the framework of a comprehensive survey of the sanitary status of the citrus industry in Iran, a sample from a private orchard of symptomless Moro blood sweet orange (Citrus sinensis) trees grafted on Mexican lime (C. aurantifolia) located at Javanan in the southern inland region was found to be infected with CVd-V. Briefly, RNAs of nucleic acid preparations from bark tissues were separated by 5% polyacrylamide gel electrophoresis (PAGE), electrotransferred to positively charged nylon membranes, immobilized by UV cross-linking, and hybridized with a full length CVd-V specific digoxigenin (DIG)-labeled DNA probe (2). A positive identification of CVd-V was made in these extracts. This positive detection of CVd-V was confirmed by reverse transcription-PCR using CVd-V specific primers of opposite polarity (5'-GACGAAGGCCGGTGAGCAGTAAGCC-3') and (5'-GACGACGACAGGTGAGTACTTTC-3') corresponding to CVd-V positions 90 to 114 and 69 to 89, respectively. Analysis of the sequence of the 293-bp amplicon (Genbank Accession No. GQ466068) revealed 99% identity with the reference sequence (Genbank Accession No. NC010165) of CVd-V. The rod-like predicted minimum free energy secondary structure of this new variant has 68.3% paired nucleotides. The changes with respect to the reference CVd-V variant are: (i) a deletion (48→-U) located in a loop of the V domain; (ii) a substitution (155A→C) located in a loop of the T_R domain of the viroid secondary structure; and (iii) two compensatory substitutions located in the upper (46A→G) and lower (244U→C) strands of the viroid secondary structure. As shown earlier, the genome of CVd-V allows little variation with a large loop located in the segment I of the secondary structure (2) being the most amenable for mutations/changes. Among the viroids that have been found naturally infecting citrus, the members of the genus Apscaviroid are not associated with specific diseases but they cause a reduction of tree size and fruit harvest (3), an effect that is enhanced when several viroids coinfect the same plant (4). Therefore, the presence of CVd-V should be considered in further indexing tests aimed at the production and distribution of pathogen-free plants in Iran. References: (1) P. Serra et al. Virology 370:102, 2008. (2) P. Serra et al. Phytopathology 98:1199, 2008. (3) C. Vernière et al. Plant Dis. 88:1189, 2004. (4) C. Vernière et al. Phytopathology 96:356, 2006.

[Evolution of the early respiratory function after lung resection for cancer]

The assessment of the postoperative risk in lung resection is a major challenge for pneumologists and thoracic surgeons. Restrictive syndromes have been observed along with a disproportionate decrease of FEV1 in lobectomies. The purpose of the present study is to describe the early response of pulmonary function after thoracotomy and resection for lung cancer. In a prospective study, the authors included 31 patients (19 lobectomy patients: mean age 59+/-10 years and 12 pneumonectomy patients: mean age 56+/-9 years) without postoperative complications. Pulmonary function tests were performed before and after surgery on Days 1, 5 (D5), 10 and within the fourth month. The main aspect of the ventilation was an unexpected similarity in subgroups during the early perioperative period up to D5. When compared with the preoperative value, about a 50% decrease in the vital capacity and total lung capacity was observed. In both subgroups about a 40% decrease was noted in the inspiratory and expiratory reserve volume. In the lobectomy sub-group, the change in the forced expiratory volume in one second over forced vital capacity (FEV/FVC) ratio was found to be higher than predicted (52+/-16% at D5 versus 67+/-14% predicted). However, the FEV/FVC ratio did not change, attesting to major restrictive ventilation. Partial recovery of the FEV was dependant on the mobile volume and especially the inspiratory volume. These findings should have implications in patient management.

Congenital bilateral pseudarthrosis of the index metacarpal bones

Congenital pseudarthrosis is very rare in upper extremity, and has only previously been reported in the forearm. A case of bilateral congenital pseudarthrosis of the index metacarpal bones is described.

Effect of heterozygous beta-thalassaemia trait on coronary atherosclerosis via coronary artery disease risk factors: a preliminary study

BACKGROUND

Thalassaemia is considered the most common genetic disorder worldwide. An association between the heterozygous beta-thalassaemia trait and myocardial infarction has previously been observed. However, the relationship between heterozygous beta-thalassaemia and atherosclerosis, considering other coronary artery disease (CAD) risk factors, has remained unclear.

METHODS

A case-control study was conducted to evaluate the hypothesis that thalassaemia minor affects the likelihood of atherosclerotic plaque formation. Blood counts and blood chemistry data as well as traditional risk factors from 1,363 patients referred to heart centres for coronary angiography were recorded. Heterozygous beta-thalassaemia was diagnosed by the presence of hypochoromic-microcytic anaemia, ferritin levels > 12 ng/ml and haemoglobin-A2 levels > 3.5.

RESULTS

Chi-squared analysis showed that the prevalence of heterozygous beta-thalassaemia was not significantly different between patients with and without CAD (p > 0.05). Multivariate logistic regression analysis using CAD as the dependent variable and traditional risk factors, haematocrit, ferritin levels and heterozygous beta-thalassaemia as independent variables, did not show any significant difference either. Independent two-tailed student's t-tests showed that haematocrit levels were statistically different (p = 0.000) between CAD(+) and CAD(-) groups, but low-density lipids (LDL), high-density lipids (HDL), triglycerides (TG), total cholesterol and serum ferritin levels were not statistically different (p > 0.05).

CONCLUSION

The prevalence of heterozygous beta-thalassaemia in the case group was not significantly different from the control group. This case-control study did not support the hypothesis that thalassaemia minor affects the likelihood of atherosclerotic plaque formation.

Uric acid: a risk factor for coronary atherosclerosis?

BACKGROUND AND OBJECTIVES

It is uncertain whether high serum uric acid levels are a true independent risk factor for coronary atherosclerosis or whether the association is due to other confounding variables. We therefore studied the relationship between elevated serum uric acid levels and coronary atherosclerosis after adjustment was made for confounding factors such as age, gender, body mass index, smoking, lipid profile, blood pressure and blood glucose levels.

METHODS

A cross-sectional study was conducted on 240 patients referred for coronary angiography to heart centres in the Shahid-Chamran and Sina hospitals, Isfahan, Iran. Blood chemistry data as well as traditional risk factors and uric acid levels were measured at enrollment. We used vessel, stenosis and extent scores to indicate the degree of coronary artery involvement.

RESULTS

This study was conducted on 240 patients with a mean age of 56 +/- 10.9 years (66% male; 37% female) who underwent coronary angiography. Student's t-test analyses revealed that there were significant differences in the mean uric acid levels between male and female patients (p = 0.001). We found no statistically significant correlation between serum uric acid levels and coronary atherosclerosis (p > 0.05). In addition, multivariate logistic regression analyses, using coronary atherosclerosis as dependent variable and traditional risk factors and uric acid levels as independent variables, did not show any significant difference.

CONCLUSION

These findings indicated that uric acid is not associated with coronary atherosclerosis. Any correlation reported in other studies was probably due to the relationship between high serum uric acid levels and other cardiovascular risk factors.

Effect of Helicobacter pylori eradication or of ranitidine plus metoclopramide on Helicobacter pylori-positive functional dyspepsia. A randomized, controlled follow-up study

BACKGROUND

A definitive treatment for functional dyspepsia (FD), and the role of Helicobacter pylori eradication on the course of this disease are controversial.

AIM

To investigate the effect of a combination of acid-suppressing and prokinetic drugs or eradication therapy on the course of H. pylori-positive FD.

METHOD

A total of 157 patients with endoscopically-proven H. pylori-positive FD and no response to 4 weeks of antacid therapy were randomly divided into 2 groups. 84 were placed on bismuth subnitrate plus metronidazole and amoxicillin (group A) and 73 received ranitidine and metoclopramide for 4 weeks (group B). The severity of symptoms (7 items) were assessed on a 6-point categorical scale. Group B patients who failed to respond to their medication underwent eradication therapy after 3 months. All patients were followed and assessed for 9 months after the end of therapy by the same clinicians who initiated the therapy.

RESULTS

At the end of the medication period, symptom's score decreased significantly, and to the same extent. At 3-month follow-up moderate or complete response was achieved in 27.4% (group A) and 19.2% (group B) by intention-to-treat analysis. 34 patients of group B, not responding to treatment, underwent eradication therapy and followed as group A. Eradication of H. pylori was successful in 60 of 110 controlled patients (54%). After 9-month follow-up, complete or moderate response was observed in only 30% of 60 patients in whom H. pylori had been eradicated (intention-to-treat analysis), compared to 38% in 50 noneradicated cases (p > 0.05, 95% CI: 19-43 vs. 24-52).

CONCLUSION

Eradication therapy with bismuth compound is effective as ranitidine plus metoclopramide in a subgroup of patients with FD not responding to antacid therapy. There is no difference in improvement between patients cured or not cured from H. pylori infection. This suggests that bismuth compounds were effective in FD when used in the eradication regimen. Combination therapy with acid-suppressing drugs plus prokinetic and bismuth seems to hold promise for FD.

Cyclosporin A is a promising alternative to corticosteroids in autoimmune hepatitis

Autoimmune hepatitis (AIH), a chronic T-cell-mediated liver injury, is treated with corticosteroids with or without Azathioprine. Corticosteroids are not universally effective and have serious side effects. Cyclosporin A was effective in refractory cases. To assess efficacy and safety of Cyclosporin A (Neoral) in induction of remission in AIH patients this study was performed. Nineteen consenting AIH patients (nine treatment-naive) were treated with cyclosporin A in an open label trial and followed for 26 weeks. Liver biopsy was done and hepatitis activity index (HAI) determined at the beginning and end of treatment. Four patients did not complete the study for various reasons. Mean AST and ALT levels decreased from 948.7 +/- 103.5 and 454.8 +/- 354 to 100.6 +/- 111.8 and 78.5 +/- 40.3 (P < 0.03, P < 0.001) respectively. HAI decreased from 15.2 +/- 3.16 to 7.14 +/- 4.01 (P < 0.005). Serum creatinine did not change significantly. In conclusion, low-dose cyclosporin A appears to be safe and effective even in treatment-naive autoimmune hepatitis patients. Randomized controlled trials are warranted.

Using coronary calcification scanning in the clinical practice of preventive cardiology

Preventive therapies such as cholesterol reduction significantly reduce the risk of acute coronary events. Diagnostic tools that identify asymptomatic coronary atherosclerosis would permit initiation of aggressive preventive therapies at an earlier stage of coronary disease. Histologic and angiographic data demonstrate that coronary calcium has a very high sensitivity for the presence of coronary plaque. Therefore, coronary calcification can be regarded as a marker for coronary atherosclerosis. Coronary calcium scanning has been suggested as a tool for identification of a high-risk asymptomatic patient group. It can be utilized to guide the aggressiveness of risk factor modification and therapeutic preventive interventions toward those at higher risk for future events. Based on the available data, we review the clinical use of coronary calcium scanning in preventive cardiology.

MHC class II genes influence the susceptibility to chronic active hepatitis C

BACKGROUND/AIMS

Chronic hepatitis C develops in more than 70% of hepatitis C virus infected subjects. Viral factors influence the disease course, but little is known about the importance of host factors.

METHODS

Frequencies of major histocompatibility complex (MHC) class I and class II antigens were analyzed in two groups of patients with chronic hepatitis C virus infection and in control subjects. MHC class I typing was done by standard microlymphocytotoxicity assays. DRB1 and DQA1 genotyping was done by PCR based typing methods.

RESULTS

DRB1*0301 was found in 26 of 75 patients with chronic hepatitis C virus infection (34.7%) and in 12 of 101 control subjects (11.9%) (relative risk 3.9; p < 0.001). Homozygosity for this allele appeared to confer a stronger risk. In contrast, DRB1*1301 was detected in three subjects with persistent infection (4.0%) compared to 21 control subjects (20.8%) (relative risk 0.2; p < 0.008). This allele was linked with DQA1*0103, which was found in 10 patients (13.3%) compared to 34 control subjects (33.7%) (relative risk 0.31; p < 0.003). An even stronger protective effect was provided by the presence of DRB1*1301 and DQA1*0103 (relative risk 0.08; p < 0.005). These findings were confirmed in a second group of chronic hepatitis C virus infected patients.

CONCLUSIONS

The MHC class II allele DRB1*0301 appears to predispose to progression to chronic active hepatitis C, whereas the class II alleles DRB1*1301 and DQA1*0103 appear to provide protection against chronic active infection with hepatitis C virus.

HLA-DRB1*1301 and *1302 protect against chronic hepatitis B

BACKGROUND/AIMS

The outcome of acute hepatitis B infection may be influenced by host factors like the major histocompatibility complex (MHC). We have investigated MHC class I and class II antigens in patients with chronic hepatitis B compared to a healthy control population. To confirm the findings of this first study we performed a second study in a group of subjects who had spontaneously recovered from acute hepatitis B infection.

METHODS

Frequencies of MHC class I and class II antigens were analyzed in patients with chronic hepatitis B virus infection and in control subjects. MHC class I typing was done by standard microlymphocytotoxicity assays. DRB1 and DQA1 genotypes were determined by polymerase chain reaction based typing methods.

RESULTS

In the first study the class II allele HLA-DRB1*1301-02 was found in 4 of 70 subjects with chronic hepatitis B virus infection (5.7%) compared to 27 of 101 healthy controls (26.7%, relative risk 0.17; p=0.001; p(corr)=0.025). This protective effect of the DRB1*1301-02 allele was confirmed in the second study. Eight of 24 patients (33.3%) who cleared hepatitis B virus spontaneously were positive for DRB1*1301-02 (relative risk of developing chronic infection compared to chronic hepatitis B subjects 0.12; p=0.004). Subtyping confirmed that 1301 and 1302 were both decreased in frequency in patients with chronic hepatitis B.

CONCLUSIONS

The MHC class II allele DRB1* 1301-02 is associated with protection from chronic hepatitis B in Caucasian patients.

Series coupled non-contractile elements are functionally unimportant in the isolated heart

OBJECTIVE

In order to evaluate possible artefact in interpretations of contractile behaviour in isolated heart experiments, the relative elastances of series coupled non-contractile and contractile components of the left ventricle of the isolated heart were evaluated.

METHODS

Hearts were isolated from ferrets and rabbits and mounted on a servo-controlled volume regulation device. These hearts were made to beat isovolumetrically until a selected volume perturbation was introduced. Constant flow volume withdrawals at two flow values were performed over a period of < 20 ms centred around the time of peak isovolumetric pressure. Three levels of isovolumetric pressure were produced using basal, extrasystolic, and potentiated beats. Pressure responses to volume withdrawals at two flows and three isovolumetric pressures were then analysed using a mathematical model to evaluate relative values of series coupled contractile and non-contractile elastances. To validate the analysis procedure, a non-contractile series artefact with known elastance was coupled to the left ventricle; volume perturbations were then applied to the coupled left ventricle-artefact system; responses were analysed and the estimate of series coupled non-contractile elastance was compared to the known elastance of the added artefact.

RESULTS

A wide range of isovolumetric pressures [208(SD 40) mmHg] was produced in the ferret with basal, extrasystolic, and potentiated beats. A lesser range of isovolumetric pressures [50(15) mmHg] was produced in the rabbit. The mathematical model fitted the data very well in both the ferret and rabbit. The elastance of the series coupled non-contractile component could be estimated only in some ferrets. When estimated in the ferret, the elastance of the series coupled non-contractile component was never less than 4x that of the contractile component. When a series artefact of sufficiently low value was coupled with the native left ventricle, the elastance of the non-contractile component could be reliably estimated in both ferrets and rabbits and the estimated value approximated that of the added artefact. This indicated that the elastance of the series coupled non-contractile component of the native left ventricle was much higher than that of the added artefact.

CONCLUSIONS

The series coupled non-contractile component of the isolated heart possesses a very much higher elastance than the contractile component. In fact, the elastance of the non-contractile component is so great that it contributes very little to the dynamic behaviour of the left ventricle. Virtually all of the elastance of the left ventricle of the isolated heart is due to the contractile component.

Similarities between dynamic elastance of left ventricular chamber and papillary muscle of rabbit heart

The frequency-dependent dynamic elastance of the left ventricle (LV) of isolated rabbit heart was determined and compared with dynamic stiffness of excised rabbit papillary muscle. Comparison was made in three states: 1) relaxed, 2) BaCl2 contracture, and 3) rigor. Dynamic chamber elastance was determined by pressure-to-volume ratio at 12 frequencies of sinusoidal volume variation between 0.1 and 30 Hz. Dynamic elastance during BaCl2 contracture was distinctly different from that during either relaxed or rigor states. Characteristics of BaCl2 contracture were 1) as frequency increased, polar plot of real and imaginary elastance showed a progressively opening clockwise spiral that tended eventually to become tangent to the apogee of a semi-circle by 30 Hz; 2) modulus spectrum exhibited asymptotes at low and high frequencies with an intervening dip to a minimum at 1.25 Hz; and 3) phase showed a sharp transition at dip frequency from small negative values at lower frequencies to large positive values at intermediate frequencies and then declined at highest frequencies. There was little dependence of dynamic elastance on frequency in both relaxed and rigor states. Dynamic muscle stiffness exhibited all features of dynamic chamber elastance in all three states. We concluded that dynamic elements responsible for myofiber stiffness were also responsible for LV chamber elastance. Furthermore, it was possible to describe and interpret dynamic chamber elastance and muscle stiffness with a common model based on muscle cross-bridge theory. This model did a reasonable job of reproducing all important features of experimentally observed LV chamber elastance and muscle stiffness. Thus dynamic homologies between chamber and muscle were established in experimental data and in the fact that a single interpretive model served equally well for both chamber elastance and muscle stiffness.

Single perturbed beat vs. steady-state beats for assessing systolic function in the isolated heart

Single-beat and steady-state techniques for evaluating end-systolic pressure-volume relationship (ESPVR) and Frank-Starling mechanism (FSM) in the crystalloid-perfused isolated rabbit heart were compared. In the single-beat technique, a train of stable isovolumic beats was interrupted with a single perturbed beat that either ejected against various levels of imposed isobaric load (ESPVR protocol) or beat isovolumically against various levels of end-diastolic volume (V(ED); FSM protocol). In steady-state technique, sustained beating was established, isobarically, at each of various loads (ESPVR protocol) or, isovolumically, at each of various V(ED) values (FSM protocol). ESPVR from steady-state technique lay above and to the left of that from single-beat technique. Contractile state was not uniform within steady-state technique, whereas it was uniform within single-beat technique. In the FSM protocol, single-beat technique exhibited the following features relative to steady-state technique: 1) greater range of developed pressures, 2) steeper ascending limb and more sharply defined maxima, 3) higher maximal developed pressure (Pdmax), and 4) greater volume at Pdmax(Vmax). Again. a common contractile state existed within single-beat technique but not within steady-state technique. It was concluded that single-beat technique was preferable to steady-state technique for evaluating ESPVR and FSM because 1) single-beat technique required less time for obtaining data, 2) single-beat technique allowed identification of uncomplicated values of Pdmax and Vmax, and 3) single-beat technique provided a common contractile-state reference for all data, whereas steady-state technique did not.

Method for studying arterial wave transmission effects on left ventricular function

A technique for studying the real-time effects of arterial wave reflections on the performance of the isolated left ventricle was investigated. Real-time arterial loading of an isolated ferret heart with an asymmetric T-tube wave transmission model was obtained with the use of a multiprocessor computer control system and a volume control linear motor pump. The multiprocessor computer system was programmed to compute the instantaneous aortic flow from the instantaneous ventricular pressure. The time integral of the flow was used as a command to the linear motor pump to control the instantaneous ventricular volume. This loading system allowed the imposition of a wide variety of vascular impedances on the ventricle by changing the parameters of the asymmetric T-tube model.