Unlocking cardiac motion: assessing software and machine learning for single-cell and cardioid kinematic insights

The heart coordinates its functional parameters for optimal beat-to-beat mechanical activity. Reliable detection and quantification of these parameters still represent a hot topic in cardiovascular research. Nowadays, computer vision allows the development of open-source algorithms to measure cellular kinematics. However, the analysis software can vary based on analyzed specimens. In this study, we compared different software performances in in-silico model, in-vitro mouse adult ventricular cardiomyocytes and cardioids. We acquired in-vitro high-resolution videos during suprathreshold stimulation at 0.5-1-2 Hz, adapting the protocol for the cardioids. Moreover, we exposed the samples to inotropic and depolarizing substances. We analyzed in-silico and in-vitro videos by (i) MUSCLEMOTION, the gold standard among open-source software; (ii) CONTRACTIONWAVE, a recently developed tracking software; and (iii) ViKiE, an in-house customized video kinematic evaluation software. We enriched the study with three machine-learning algorithms to test the robustness of the motion-tracking approaches. Our results revealed that all software produced comparable estimations of cardiac mechanical parameters. For instance, in cardioids, beat duration measurements at 0.5 Hz were 1053.58 ms (MUSCLEMOTION), 1043.59 ms (CONTRACTIONWAVE), and 937.11 ms (ViKiE). ViKiE exhibited higher sensitivity in exposed samples due to its localized kinematic analysis, while MUSCLEMOTION and CONTRACTIONWAVE offered temporal correlation, combining global assessment with time-efficient analysis. Finally, machine learning reveals greater accuracy when trained with MUSCLEMOTION dataset in comparison with the other software (accuracy > 83%). In conclusion, our findings provide valuable insights for the accurate selection and integration of software tools into the kinematic analysis pipeline, tailored to the experimental protocol.

Ionically Modified Gelatin Hydrogels Maintain Murine Myogenic Cell Viability and Fusion Capacity

For tissue engineering of skeletal muscles, there is a need for biomaterials which do not only allow cell attachment, proliferation, and differentiation, but also support the physiological conditions of the tissue. Next to the chemical nature and structure of the biomaterial, its response to the application of biophysical stimuli, such as mechanical deformation or application of electrical pulses, can impact in vitro tissue culture. In this study, gelatin methacryloyl (GelMA) is modified with hydrophilic 2-acryloxyethyltrimethylammonium chloride (AETA) and 3-sulfopropyl acrylate potassium (SPA) ionic comonomers to obtain a piezoionic hydrogel. Rheology, mass swelling, gel fraction, and mechanical characteristics are determined. The piezoionic properties of the SPA and AETA-modified GelMA are confirmed by a significant increase in ionic conductivity and an electrical response as a function of mechanical stress. Murine myoblasts display a viability of >95% after 1 week on the piezoionic hydrogels, confirming their biocompatibility. The GelMA modifications do not influence the fusion capacity of the seeded myoblasts or myotube width after myotube formation. These results describe a novel functionalization providing new possibilities to exploit piezo-effects in the tissue engineering field.

Video analysis of ex vivo beating hearts during preservation on the TransMedics® organ care system

Background

Reliable biomarkers for assessing the viability of the donor hearts undergoing ex vivo perfusion remain elusive. A unique feature of normothermic ex vivo perfusion on the TransMedics® Organ Care System (OCS™) is that the donor heart is maintained in a beating state throughout the preservation period. We applied a video algorithm for an in vivo assessment of cardiac kinematics, video kinematic evaluation (Vi.Ki.E.), to the donor hearts undergoing ex vivo perfusion on the OCS™ to assess the feasibility of applying this algorithm in this setting.

Methods

Healthy donor porcine hearts (n = 6) were procured from Yucatan pigs and underwent 2 h of normothermic ex vivo perfusion on the OCS™ device. During the preservation period, serial high-resolution videos were captured at 30 frames per second. Using Vi.Ki.E., we assessed the force, energy, contractility, and trajectory parameters of each heart.

Results

There were no significant changes in any of the measured parameters of the heart on the OCS™ device over time as judged by linear regression analysis. Importantly, there were no significant changes in contractility during the duration of the preservation period (time 0-30 min, 918 ± 430 px/s; time 31-60 min, 1,386 ± 603 px/s; time 61-90 min, 1,299 ± 617 px/s; time 91-120 min, 1,535 ± 728 px/s). Similarly, there were no significant changes in the force, energy, or trajectory parameters. Post-transplantation echocardiograms demonstrated robust contractility of each allograft.

Conclusion

Vi.Ki.E. assessment of the donor hearts undergoing ex vivo perfusion is feasible on the TransMedics OCS™, and we observed that the donor hearts maintain steady kinematic measurements throughout the duration.

Enhancing Myoblast Fusion and Myotube Diameter in Human 3D Skeletal Muscle Constructs by Electromagnetic Stimulation

Skeletal muscle tissue engineering (SMTE) aims at the in vitro generation of 3D skeletal muscle engineered constructs which mimic the native muscle structure and function. Although native skeletal muscle is a highly dynamic tissue, most research approaches still focus on static cell culture methods, while research on stimulation protocols indicates a positive effect, especially on myogenesis. A more mature muscle construct may be needed especially for the potential applications for regenerative medicine purposes, disease or drug disposition models. Most efforts towards dynamic cell or tissue culture methods have been geared towards mechanical or electrical stimulation or a combination of those. In the context of dynamic methods, pulsed electromagnetic field (PEMF) stimulation has been extensively used in bone tissue engineering, but the impact of PEMF on skeletal muscle development is poorly explored. Here, we evaluated the effects of PEMF stimulation on human skeletal muscle cells both in 2D and 3D experiments. First, PEMF was applied on 2D cultures of human myoblasts during differentiation. In 2D, enhanced myogenesis was observed, as evidenced by an increased myotube diameter and fusion index. Second, 2D results were translated towards 3D bioartificial muscles (BAMs). BAMs were subjected to PEMF for varying exposure times, where a 2-h daily stimulation was found to be effective in enhancing 3D myotube formation. Third, applying this protocol for the entire 16-days culture period was compared to a stimulation starting at day 8, once the myotubes were formed. The latter was found to result in significantly higher myotube diameter, fusion index, and increased myosin heavy chain 1 expression. This work shows the potential of electromagnetic stimulation for enhancing myotube formation both in 2D and 3D, warranting its further consideration in dynamic culturing techniques.

The value of admission Troponin I to predict outcomes in suspected infections in elderly patients admitted in Internal Medicine: results from the SOFA-T collaboration, a multi-center study

Elderly patients affected by suspected infection and declining clinical conditions can be admitted to stepdown units (SDU), but a risk stratification is necessary to optimize their management. Admission troponin I (aTnI) has a prognostic role, however, one of the most commonly used stratification tools, the Sequential Organ Failure Assessment score (SOFA), does not consider myocardial injury. With this paper, we aimed to evaluate the prognostic accuracy of a new score, named SOFA-T, considering both SOFA score and aTnI in a cohort of elderly patients admitted to the stepdown beds of two Internal Medicine departments. Patients aged > 65 years admitted in SDU of two different hospitals of the same region in a 12-months timeframe were retrospectively assessed obtaining age, sex, days of admission, in-hospital death, SOFA, aTnI and comorbidities. The best aTnI cutoff for in-hospital death was calculated with ROC curve analysis; dichotomous variables were compared with chi-squared test; continuous variables were compared with t test or Mann-Whitney test. We obtained a cohort of 390 patients. The best aTnI cutoff was 0.31 ng/ml: patients with increased aTnI had higher risk of in-hospital death (OR: 1.834; 95% CI 1.160-2.900; p = 0.009), and higher SOFA (6.81 ± 2.71 versus 5.97 ± 3.10; p = 0.010). Adding aTnI to SOFA increased significantly the area under the curve (AUC_SOFA = 0.68; 95% CI 0.64-0.73; AUC_SOFA-T = 0.71; 95% CI 0.65-0.76; p = 0.0001), with a slight improvement of the prognostic performance. In elderly patients admitted to SDU for suspected infection, sepsis or septic shock, aTnI slightly improves the accuracy of SOFA score of the in-hospital death prediction.

Correlation between HIV and HCV in Brazilian prisoners: evidence for parenteral transmission inside prison

OBJECTIVE

It is an accepted fact that confinement conditions increase the risk of some infections related to sexual and/or injecting drugs practices. Mathematical techniques were applied to estimate time-dependent incidence densities of HIV infection among inmates.

METHODS

A total of 631 prisoners from a Brazilian prison with 4,900 inmates at that time were interviewed and their blood drawn. Risky behavior for HIV infection was analyzed, and serological tests for HIV, hepatitis C and syphilis were performed, intended as surrogates for parenteral and sexual HIV transmission, respectively. Mathematical techniques were used to estimate the incidence density ratio, as related to the time of imprisonment.

RESULTS

Prevalence were: HIV - 16%; HCV - 34%; and syphilis - 18%. The main risk behaviors related to HIV infection were HCV prevalence (OR=10.49) and the acknowledged use of injecting drugs (OR=3.36). Incidence density ratio derivation showed that the risk of acquiring HIV infection increases with the time of imprisonment, peaking around three years after incarceration.

CONCLUSIONS

The correlation between HIV and HCV seroprevalence and the results of the mathematical analysis suggest that HIV transmission in this population is predominantly due to parenteral exposure by injecting drug, and that it increases with time of imprisonment.

[The effect of cardiovascular rehabilitation on the variability of the RR cycle after a first uncomplicated acute myocardial infarct]

BACKGROUND

The aim of this study was to verify the changes in the autonomic balance by means of heart rate variability assessment in patients with myocardial infarction referred for cardiac rehabilitation.

METHODS

We studied 122 patients (79 males, 43 females, mean age 56 +/- 5 years), with a first uncomplicated myocardial infarction (anterior 48, thrombolysis 72), Killip class 1, preserved left ventricular function (ejection fraction 49 +/- 6%). All patients were free of inducible residual ischemia. Four weeks after myocardial infarction, patients were randomized into two groups; Group 1 (n = 58) referred for an 8 week cardiac rehabilitation program (scheduled: 24 sessions); Group 2 (n = 64): normal daily physical activity. During a 24-hour Holter ECG monitoring the following parameters were calculated in pharmacological wash-out at randomization (T0) and at the end of cardiac rehabilitation/control period (T1): mean value of RR intervals (RR), its standard deviation (SDNN), pNN50, rMSSD in the time domain; low frequency (LF) and high frequency (HF) value and the LF/HF ratio in the frequency domain. T1-T0 changes in percent values (delta %) were considered and compared between the two groups.

RESULTS

Thirty-one patients were excluded from the study either for insufficient adhesion to the cardiac rehabilitation program (< 13 sessions, 22 patients) or recurrent ischemia (3 Group 1 patients and 3 Group 2 patients) and non-assessable 24-hour Holter ECG monitoring (3 patients). Thirty-one Group 1 patients and 60 Group 2 patients completed the study with a first and a second 24-hour Holter ECG monitoring performed at 30 +/- 3 days and 60 +/- 4 days respectively. At the same time an ergospirometric test was performed to evaluate cardiopulmonary function by means of exercise time, maximum oxygen consumption, anaerobic threshold, exercise time at the anaerobic threshold, and maximum oxygen consumption at the anaerobic threshold. Twenty-eight Group 1 patients and 44 Group 2 patients completed the study with a first and a second ergospirometric test. Baseline heart rate variability parameters were comparable in the two groups. During the observation period only in Group 1 patients heart rate variability parameters changed significantly: RR (Group 1 = +18.3 +/- 21.3; Group 2 = +4.2 +/- 5.2, p = 0.000), pNN50 (Group 1 = 45.0 +/- 38.9; Group 2 = +24.2 +/- 34.7, p = 0.011), HF (Group 1 = +81.6 +/- 124; Group 2 = -28.7 +/- 75.4, p = 0.014) and LF/HF ratio (Group 1 = -26.0 +/- 16.1; Group 2 = -4.9 +/- 6.1, p = 0.062). There were no significant differences in SDNN, rMSSD and LF. A linear correlation between delta LF/HF ratio and baseline LF/HF ratio values was found in Group 1 (r = 0.489, p = 0.006), whereas no correlation was found between this parameter and age, ejection fraction, creatine phosphokinase, and infarct localization. Group 1 patients had a significant improvement in exercise tolerance compared to Group 2 patients.

CONCLUSIONS

A cardiac rehabilitation program positively modifies the sympatho-vagal balance in patients with uncomplicated myocardial infarction, increasing the parasympathetic tone and exercise tolerance.

A theoretical model of the evolution of virulence in sexually transmitted HIV/AIDS

INTRODUCTION

The evolution of virulence in host-parasite relationships has been the subject of several publications. In the case of HIV virulence, some authors suggest that the evolution of HIV virulence correlates with the rate of acquisition of new sexual partners. In contrast some other authors argue that the level of HIV virulence is independent of the sexual activity of the host population.

METHODS

Provide a mathematical model for the study of the potential influence of human sexual behaviour on the evolution of virulence of HIV is provided.

RESULTS

The results indicated that, when the probability of acquisition of infection is a function both of the sexual activity and of the virulence level of HIV strains, the evolution of HIV virulence correlates positively with the rate of acquisition of new sexual partners.

CONCLUSION

It is concluded that in the case of a host population with a low (high) rate of exchange of sexual partners the evolution of HIV virulence is such that the less (more) virulent strain prevails.

[Late ventricular potentials and acute myocardial infarction]

BACKGROUND

The presence of late ventricular potentials was evaluated in a group of patients following acute myocardial infarction hospitalised in our division.

MATERIALS AND METHODS

Recordings were made between the 10th and 12th day of the pathology. The criteria for positivity were the presence of three parameters: QRSD > or = 114 msec, LAS 40 > or = 38 msec, RMS 40 < or = 20 mv. These were present in 21 patients (18 males and 3 females). Inferior acute myocardial infarction (AMI) was found to be present in 15 cases, anterior AMI in 4 cases and AMI with an unspecified localisation in 2 cases. The mean duration of qrsd was 122 msec, the mean duration of low amplitude potentials (LAS 40) were 53.5 msec, the mean amplitude of the last 40 msec (RMS 40 was 8.9 mv).

CONCLUSIONS

In conclusion, the authors affirm that late potentials were present in the majority of patients with inferior AMI and the search for the latter represents an important stage in the post-AMI prognostic stratification. Delta is the positive correlation between late potentials and ventricular tachycardia in postinfarction. This non-invasive test is comparable to electrophysiological induction tests in terms of predictive capacity of arrhythmic event and/or sudden death.

[Comparison of anti-arrhythmic therapy guided by the transesophageal electropharmacologic test and emperic therapy in the prophylaxis of atrial fibrillation recurrence]

BACKGROUND

There is no written data about the efficacy of transesophageal electropharmacologic test (TEPT) to guide antiarrhythmic therapy in the prophylaxis of paroxysmal atrial fibrillation (PAF) recurrences. Aim of this study was to assess the efficacy of TEPT compared to empiric treatment in the prophylaxis of PAF.

METHODS

One-hundred-sixty patients (pts) with previous episodes of PAF were randomized in two groups: Gr A (90 pts) was submitted to basal transesophageal electrophysiologic study (BTES); Gr B (70 pts) was submitted to randomized empiric antiarrhythmic therapy with flecainide (F), propafenone (P) and sotalol (S). The end-points of stimulation protocol in Gr A were the induction of sustained atrial fibrillation (SAF)- > or = 1 min duration- or the end of protocol. SAF was inducible in 68/90 pts (Gr A1) while it was not in 22/90 pts (Gr A2). Pts in Gr A1 were subsequently submitted to TEPT at steady-state of F, P or S randomized in first choice. Pts responders (R) (SAF non inducible) were submitted to TEPT with other antiarrhythmic drugs randomized in second choice: R were followed-up with the same drug in chronic oral assumption, while non responders (NR) were submitted to TEPT with the last drug and followed-up with the same drug both in R and NR case. The same stimulation protocol was employed in TEPT as in BTES. Pts in Gr A2 withdrew from the study. During follow-up all-pts were submitted to periodic specialist examinations every three months. In case of PAF recurrence pts withdrew from the study.

RESULTS

Mean follow-up duration in the study population was 17.5 +/- 8.5 months. One-hundred-eight TEPT were performed in Gr A1: 36 tests with F, 40 with P and 32 with S. Twenty pts were R with F (55% of tests) and 17 finished the follow-up, 22 pts were R with P (55% of tests) and 16 finished the follow-up, 19 pts were R with S (59% of tests) and 15 finished the follow-up; 3 pts with F, 2 pts with P and 2 pts with S were NR in last choice and finished the follow-up. In Gr A1 61/68 pts (90%) were R and 55/68 (81%) finished the follow-up (13 pts withdrew from the study). In Gr B (70 pts) 23 pts were randomized to F and 20 finished the follow-up, 24 pts were randomized to P and 20 finished the follow-up, 23 pts were randomized to S and 20 finished the follow-up (10 pts withdrew from the study). PAF recurrences during follow-up in Gr A1 were in 15/55 pts (27%): 9/48 pts (19%) R and 6/7 pts (86%) NR, and in Gr B in 41/60 pts (68%). Gr A1 vs Gr B p < 0.001. Univariate and multivariate statistical analysis showed the empiric treatment as the only variable with high predictive value for PAF recurrences (risk ratio 1.53). PPV and NPV of TEPT were respectively 86 and 81%.

CONCLUSIONS

TEPT-guided antiarrhythmic therapy in the prophylaxis of PAF recurrences seems to be an effective method in predicting the efficacy of the chronic antiarrhythmic therapy, when compared to the empiric treatment. The non inducibility of SAF at TEPT would have a high predictive value for event-free follow-up.

[Bacterial endocarditis in an infectious diseases department: our experience]

The infective endocarditis remains a serious disease. The microbiologic, immunologic and technologic researches have contributed to the diagnosis and cure of the disease. The Authors report the results on ten cases of infective endocarditis that came to their observation in the last five years. They emphasize the more important epidemiologic aspects, the role of the laboratory and instrumental results to define an early diagnosis and the best results about of the therapies used

Prognostic value of high dose dipyridamole echocardiography in patients with chronic coronary artery disease and preserved left ventricular function

OBJECTIVES

The prognostic value of dipyridamole echocardiography was assessed in patients with chronic coronary artery disease and preserved left ventricular function.

BACKGROUND

Few data are available on the prognostic value of dipyridamole echocardiography in patients with a low risk of cardiac events.

METHODS

Two hundred sixty-eight consecutive patients with stable, proven or suspected coronary artery disease and ejection fraction > or = 0.40 underwent high dose (up to 0.84 mg/kg body weight) dipyridamole echocardiography. In 204 patients definite exercise electrocardiographic (ECG) results were also available.

RESULTS

During a mean (+/- SD) follow-up period of 16 +/- 8 months (range 6 to 36), 33 spontaneous events occurred: 15 "hard" events (cardiac death [n = 6], myocardial infarction [n = 9]) and 18 "soft" events (unstable angina). Events occurred more frequently in patients with positive findings on dipyridamole echocardiography (59% vs. 3%, p < 0.001; hard events 24% vs. 2%, p < 0.01). A positive response at the low dose (up to 0.56 mg/kg) identified patients with a high incidence of hard events (7 of 16 patients, sensitivity 50%, specificity 96%). In patients with an exercise ECG, a comparable sensitivity for cardiac events was found (89% vs. 93%, p = NS), but dipyridamole echocardiography was more specific (91% vs. 61%, p < 0.01). A positive response on the low work load exercise ECG (< 8 min) and a positive response to low dose dipyridamole echocardiography had similar accuracy (82% vs. 90%, p = NS). Cox analysis identified dipyridamole echocardiography as the best predictor of cardiac events (odds ratio [OR] 20.9, 95% confidence interval [CI] 10.8 to 37.9); the highest risk of hard events was found in patients with a positive response to low dose dipyridamole echocardiography (OR 25.4, 95% CI 12.2 to 54.1).

CONCLUSIONS

In patients with chronic coronary artery disease and a low incidence of cardiac events, dipyridamole echocardiography was effective in prognostic stratification, and positive low work load exercise ECG results were a reliable predictor of subsequent events. Consequently, dipyridamole echocardiography should be considered a complementary tool in the presence of high work load positivity or ambiguous exercise ECG results.

[A comparison between flecainide and sotalol in the prevention of recurrences of paroxysmal atrial fibrillation]

OBJECTIVES

Aim of the present study was to assess the efficacy and safety of flecainide (F) and sotalol (S) for the prevention of recurrences of paroxysmal atrial fibrillation (PAF).

METHODS

Sixty-six patients with PAF (> or = 3 episodes of atrial fibrillation in the last year) in sinus rhythm, were randomized to pharmacological oral treatment with F (20 patients-Group A), with S (20 patients-Group B) and placebo (P) (26 patients-Group C). During the follow-up (one year duration) were evaluated on I, III, VI and XII months the number and tolerance of the atrial fibrillation recurrences, cardiac and/or noncardiac side effects. The patients with more than two recurrences in the same follow-up interval withdrew from the study. In each patient 14 clinical and laboratory variables were evaluated.

RESULTS

After 12 months were arrhythmia-free respectively 70% of Group A patients, 60% of Group B patients, 27% of Group C patients. Univariate analysis showed that treatment with F was related to decrease of atrial fibrillation recurrences (one recurrence 67%, two recurrences 81%, three recurrences 81%), treatment with S was related to decrease of recurrences (two recurrences 59%); the variable most significantly related to the risk of arrhythmia recurrence is the higher value of basal cardiac rate (one recurrence t = 2.15, two t = 2.22, three t = 2.96, four t = 2.06). There was not statistically significant difference in maintenance of sinus rhythm at the end of the follow-up between the groups of patients on F and S (p = 0.163); treatment efficacy was significantly higher than P (p = 0.002). Multivariate analysis showed that treatment with F and S decreases the risk of arrhythmia recurrence respectively of 85% and 76% versus placebo at the end of the follow-up. The incidence of cardiac and/or noncardiac side effects was not clinically significant.

CONCLUSION

F and S are both effective and safe for prevention of PAF, with 70% and 60% respectively of patients arrhythmia-free after 12 months of treatment. Side effects were common, but clinically significant adverse events were uncommon. A higher value of basal cardiac rate was predictive of atrial fibrillation recurrences in the patients during treatment.

Echocardiographic evaluation of left ventricular outflow tract obstruction in complete transposition of the great arteries

Subpulmonic stenosis in complete d-transposition of the great arteries (d-TGA) is a frequently associated malformation, the precise diagnosis of which is essential for optimal medical and surgical treatment. Sixteen patients with d-TGA and subpulmonic stenosis have been studied by M-mode and two-dimensional (2DE) echocardiography and cardiac catheterization. Dynamic obstruction was found in six patients and fixed stenosis in 10. Systolic anterior motion of the mitral valve without fixed obstruction of the left ventricular outflow tract (LVOT) was present in patients with dynamic stenosis. Measurements of left ventricular end-diastolic posterior wall thickness to minor semiaxis ratio correlated well (p less than 0.001) with the pressure gradient across the LVOT. Various types of anatomic fixed obstruction are described. M-mode echocardiography provides assessment of dynamic obstruction but does not allow quantitative evaluation of the length of the narrowed segment. The latter can be achieved by 2DE, which offers improved definition of different anatomic types.