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Fluid structure interaction simulation of left ventricular flow dynamics under left ventricular assist device support

Ong CW, Chan BT, Lim E, Abu Osman NA, Abed AA, Dokos S, et al.

Annu Int Conf IEEE Eng Med Biol Soc, 2012;2012:6293-6.
PMID: 23367368 DOI: 10.1109/EMBC.2012.6347433

For patient's receiving mechanical circulatory support, malfunction of the left ventricular assist device (LVADs) as well as mal-positioning of the cannula imposes serious threats to their life. It is therefore important to characterize the flow pattern and pressure distribution within the ventricle in the presence of an LVAD. In this paper, we present a 2D axisymmetric fluid structure interaction model of the passive left ventricle (LV) incorporating an LVAD cannula to simulate the effect of the LVAD cannula placement on the vortex dynamics. Results showed that larger recirculation area was formed at the cannula tip with increasing cannula insertion depth, and this is believed to reduce the risk of thrombus formation. Furthermore, we also simulated suction events (collapse of the LV) by closing the inlet. Vortex patterns were significantly altered under this condition, and the greatest LV wall displacement was observed at the part of the myocardium closest to the cannula tip.

Matched MeSH terms: Heart Ventricles/physiopathology*
Simulation of left ventricle flow dynamics with dilated cardiomyopathy during the filling phase

Chan BT, Ong CW, Lim E, Abu Osman NA, Al Abed A, Lovell NH, et al.

Annu Int Conf IEEE Eng Med Biol Soc, 2012;2012:6289-92.
PMID: 23367367 DOI: 10.1109/EMBC.2012.6347432

Dilated cardiomyopathy (DCM) is a common cardiac disease which leads to the deterioration in cardiac performance. A computational fluid dynamics (CFD) approach can be used to enhance our understanding of the disease, by providing us with a detailed map of the intraventricular flow and pressure distributions. In the present work, effect of ventricular size on the intraventricular flow dynamics and intraventricular pressure gradients (IVPGs) was studied using two different implementation methods, i.e. the geometry-prescribed and the fluid structure interaction (FSI) methods. Results showed that vortex strength and IVPGs are significantly reduced in a dilated heart, leading to an increased risk of thrombus formation and impaired ventricular filling. We suggest FSI method as the ultimate method in studying ventricular dysfunction as it provides additional cardiac disease prognostic factors and more realistic model implementation.

Matched MeSH terms: Heart Ventricles/physiopathology*
The role of infarct transmural extent in infarct extension: A computational study

Leong CN, Lim E, Andriyana A, Al Abed A, Lovell NH, Hayward C, et al.

Int J Numer Method Biomed Eng, 2017 Feb;33(2).
PMID: 27043925 DOI: 10.1002/cnm.2794

Infarct extension, a process involving progressive extension of the infarct zone (IZ) into the normally perfused border zone (BZ), leads to continuous degradation of the myocardial function and adverse remodelling. Despite carrying a high risk of mortality, detailed understanding of the mechanisms leading to BZ hypoxia and infarct extension remains unexplored. In the present study, we developed a 3D truncated ellipsoidal left ventricular model incorporating realistic electromechanical properties and fibre orientation to examine the mechanical interaction among the remote, infarct and BZs in the presence of varying infarct transmural extent (TME). Localized highly abnormal systolic fibre stress was observed at the BZ, owing to the simultaneous presence of moderately increased stiffness and fibre strain at this region, caused by the mechanical tethering effect imposed by the overstretched IZ. Our simulations also demonstrated the greatest tethering effect and stress in BZ regions with fibre direction tangential to the BZ-remote zone boundary. This can be explained by the lower stiffness in the cross-fibre direction, which gave rise to a greater stretching of the IZ in this direction. The average fibre strain of the IZ, as well as the maximum stress in the sub-endocardial layer, increased steeply from 10% to 50% infarct TME, and slower thereafter. Based on our stress-strain loop analysis, we found impairment in the myocardial energy efficiency and elevated energy expenditure with increasing infarct TME, which we believe to place the BZ at further risk of hypoxia. Copyright © 2016 John Wiley & Sons, Ltd.

Matched MeSH terms: Heart Ventricles/pathology; Heart Ventricles/physiopathology
Automated classification of patients with coronary artery disease using grayscale features from left ventricle echocardiographic images

Acharya UR, Sree SV, Muthu Rama Krishnan M, Krishnananda N, Ranjan S, Umesh P, et al.

Comput Methods Programs Biomed, 2013 Dec;112(3):624-32.
PMID: 23958645 DOI: 10.1016/j.cmpb.2013.07.012

Coronary Artery Disease (CAD), caused by the buildup of plaque on the inside of the coronary arteries, has a high mortality rate. To efficiently detect this condition from echocardiography images, with lesser inter-observer variability and visual interpretation errors, computer based data mining techniques may be exploited. We have developed and presented one such technique in this paper for the classification of normal and CAD affected cases. A multitude of grayscale features (fractal dimension, entropies based on the higher order spectra, features based on image texture and local binary patterns, and wavelet based features) were extracted from echocardiography images belonging to a huge database of 400 normal cases and 400 CAD patients. Only the features that had good discriminating capability were selected using t-test. Several combinations of the resultant significant features were used to evaluate many supervised classifiers to find the combination that presents a good accuracy. We observed that the Gaussian Mixture Model (GMM) classifier trained with a feature subset made up of nine significant features presented the highest accuracy, sensitivity, specificity, and positive predictive value of 100%. We have also developed a novel, highly discriminative HeartIndex, which is a single number that is calculated from the combination of the features, in order to objectively classify the images from either of the two classes. Such an index allows for an easier implementation of the technique for automated CAD detection in the computers in hospitals and clinics.

Matched MeSH terms: Heart Ventricles/ultrasonography*
The nonlinear elastic and viscoelastic passive properties of left ventricular papillary muscle of a guinea pig heart

Hassan MA, Hamdi M, Noma A

J Mech Behav Biomed Mater, 2012 Jan;5(1):99-109.
PMID: 22100084 DOI: 10.1016/j.jmbbm.2011.08.011

The mechanical behavior of the heart muscle tissues is the central problem in finite element simulation of the heart contraction, excitation propagation and development of an artificial heart. Nonlinear elastic and viscoelastic passive material properties of the left ventricular papillary muscle of a guinea pig heart were determined based on in-vitro precise uniaxial and relaxation tests. The nonlinear elastic behavior was modeled by a hypoelastic model and different hyperelastic strain energy functions such as Ogden and Mooney-Rivlin. Nonlinear least square fitting and constrained optimization were conducted under MATLAB and MSC.MARC in order to obtain the model material parameters. The experimental tensile data was used to get the nonlinear elastic mechanical behavior of the heart muscle. However, stress relaxation data was used to determine the relaxation behavior as well as viscosity of the tissues. Viscohyperelastic behavior was constructed by a multiplicative decomposition of a standard Ogden strain energy function, W, for instantaneous deformation and a relaxation function, R(t), in a Prony series form. The study reveals that hypoelastic and hyperelastic (Ogden) models fit the tissue mechanical behaviors well and can be safely used for heart mechanics simulation. Since the characteristic relaxation time (900 s) of heart muscle tissues is very large compared with the actual time of heart beating cycle (800 ms), the effect of viscosity can be reasonably ignored. The amount and type of experimental data has a strong effect on the Ogden parameters. The in vitro passive mechanical properties are good initial values to start running the biosimulation codes for heart mechanics. However, an optimization algorithm is developed, based on clinical intact heart measurements, to estimate and re-correct the material parameters in order to get the in vivo mechanical properties, needed for very accurate bio-simulation and for the development of new materials for the artificial heart.

Matched MeSH terms: Heart Ventricles*
Tetralogy of Fallot correction with transannular patch reconstruction in a patient with an anomalous right coronary artery and an unusual course of the right ventricular branch

Gonzalez SA, Sivalingam S

Indian J Thorac Cardiovasc Surg, 2021 May;37(3):329-333.
PMID: 33967425 DOI: 10.1007/s12055-020-01074-0

Anomalous coronary arteries occur in as many as 12% of patients with tetralogy of Fallot (TOF). In patients with this condition, pulmonary hypoplasia can be prohibitive in performing a valve-sparing repair, subsequently resulting in various techniques to preserve the anomalous coronary artery. The management strategy is often complex in such a situation. We report on a case of TOF with an anomalous right coronary artery crossing the right ventricular outflow tract, with an unusual course of the right ventricular (RV) branch, which precluded placement of a valved conduit. In this case, we performed a successful repair with mobilization of the anomalous coronary artery and reconstruction of the right ventricular outflow tract with a limited transannular patch.

Matched MeSH terms: Heart Ventricles
The role of regional myocardial topography post-myocardial infarction on infarct extension

Leong CO, Leong CN, Liew YM, Al Abed A, Aziz YFA, Chee KH, et al.

Int J Numer Method Biomed Eng, 2021 08;37(8):e3501.
PMID: 34057819 DOI: 10.1002/cnm.3501

Infarct extension involves necrosis of healthy myocardium in the border zone (BZ), progressively enlarging the infarct zone (IZ) and recruiting the remote zone (RZ) into the BZ, eventually leading to heart failure. The mechanisms underlying infarct extension remain unclear, but myocyte stretching has been suggested as the most likely cause. Using human patient-specific left-ventricular (LV) numerical simulations established from cardiac magnetic resonance imaging (MRI) of myocardial infarction (MI) patients, the correlation between infarct extension and regional mechanics abnormality was investigated by analysing the fibre stress-strain loops (FSSLs). FSSL abnormality was characterised using the directional regional external work (DREW) index, which measures FSSL area and loop direction. Sensitivity studies were also performed to investigate the effect of infarct stiffness on regional myocardial mechanics and potential for infarct extension. We found that infarct extension was correlated to severely abnormal FSSL in the form of counter-clockwise loop at the RZ close to the infarct, as indicated by negative DREW values. In regions demonstrating negative DREW values, we observed substantial fibre stretching in the isovolumic relaxation (IVR) phase accompanied by a reduced rate of systolic shortening. Such stretching in IVR phase in part of the RZ was due to its inability to withstand the high LV pressure that was still present and possibly caused by regional myocardial stiffness inhomogeneity. Further analysis revealed that the occurrence of severely abnormal FSSL due to IVR fibre stretching near the RZ-BZ boundary was due to a large amount of surrounding infarcted tissue, or an excessively stiff IZ.

Matched MeSH terms: Heart Ventricles
Fulltext An inverse finite element method for determining the tissue compressibility of human left ventricular wall during the cardiac cycle

Hassaballah AI, Hassan MA, Mardi AN, Hamdi M

PLoS One, 2013;8(12):e82703.
PMID: 24367544 DOI: 10.1371/journal.pone.0082703

The determination of the myocardium's tissue properties is important in constructing functional finite element (FE) models of the human heart. To obtain accurate properties especially for functional modeling of a heart, tissue properties have to be determined in vivo. At present, there are only few in vivo methods that can be applied to characterize the internal myocardium tissue mechanics. This work introduced and evaluated an FE inverse method to determine the myocardial tissue compressibility. Specifically, it combined an inverse FE method with the experimentally-measured left ventricular (LV) internal cavity pressure and volume versus time curves. Results indicated that the FE inverse method showed good correlation between LV repolarization and the variations in the myocardium tissue bulk modulus K (K = 1/compressibility), as well as provided an ability to describe in vivo human myocardium material behavior. The myocardium bulk modulus can be effectively used as a diagnostic tool of the heart ejection fraction. The model developed is proved to be robust and efficient. It offers a new perspective and means to the study of living-myocardium tissue properties, as it shows the variation of the bulk modulus throughout the cardiac cycle.

Matched MeSH terms: Heart Ventricles/physiopathology*
Evaluation of suction detection during different pumping states in an implantable rotary blood pump

Ng SC, Lim E, Mason DG, Avolio AP, Lovell NH

Artif Organs, 2013 Aug;37(8):E145-54.
PMID: 23635073 DOI: 10.1111/aor.12079

In recent times, the problem of noninvasive suction detection for implantable rotary blood pumps has attracted substantial research interest. Here, we compare the performance of various suction indices for different types of suction and non-suction events based on pump speed irregularity. A total of 171 different indices that consist of previously proposed as well as newly introduced suction indices are tested using regularized logistic regression. These indices can be classified as amplitude based (derived from the mean, maximum, and minimum values of a cycle), duration based (derived from the duration of a cycle), gradient based (derived from the first order as well as higher order differences) and frequency based (derived from the power spectral density). The non-suction event data consists of ventricular ejection with or without arrhythmia and intermittent and continuous non-opening of the aortic valve. The suction event data consists of partial ventricular collapse that occurs intermittently as well as continuously with or without arrhythmia. In addition, we also attempted to minimize the usage of multiple indices by applying the sequential forward floating selection method to find which combination of indices gives the best performance. In general, the amplitude-based and gradient-based indices performed quite well while the duration-based and frequency-based indices performed poorly. By having only two indices ([i] the maximum gradient change in positive slope; and [ii] the standard deviation of the maximum value in a cycle), we were able to achieve a sensitivity of 98.9% and a specificity of 99.7%.

Matched MeSH terms: Heart Ventricles/physiopathology*
Effect of spatial inlet velocity profiles on the vortex formation pattern in a dilated left ventricle

Chan BT, Lim E, Ong CW, Abu Osman NA

Comput Methods Biomech Biomed Engin, 2015;18(1):90-6.
PMID: 23521137 DOI: 10.1080/10255842.2013.779683

Despite the advancement of cardiac imaging technologies, these have traditionally been limited to global geometrical measurements. Computational fluid dynamics (CFD) has emerged as a reliable tool that provides flow ﬁeld information and other variables essential for the assessment of the cardiac function. Extensive studies have shown that vortex formation and propagation during the filling phase acts as a promising indicator for the diagnosis of the cardiac health condition. Proper setting of the boundary conditions is crucial in a CFD study as they are important determinants, that affect the simulation results. In this article, the effect of different transmitral velocity profiles (parabolic and uniform profile) on the vortex formation patterns during diastole was studied in a ventricle with dilated cardiomyopathy (DCM). The resulting vortex evolution pattern using the uniform inlet velocity profile agreed with that reported in the literature, which revealed an increase in thrombus risk in a ventricle with DCM. However the application of a parabolic velocity profile at the inlet yields a deviated vortical flow pattern and overestimates the propagation velocity of the vortex ring towards the apex of the ventricle. This study highlighted that uniform inlet velocity profile should be applied in the study of the filling dynamics in a left ventricle because it produces results closer to that observed experimentally.

Matched MeSH terms: Heart Ventricles/physiopathology*
Fulltext Pulsatile operation of a continuous-flow right ventricular assist device (RVAD) to improve vascular pulsatility

Ng BC, Kleinheyer M, Smith PA, Timms D, Cohn WE, Lim E

PLoS One, 2018;13(4):e0195975.
PMID: 29677212 DOI: 10.1371/journal.pone.0195975

Despite the widespread acceptance of rotary blood pump (RBP) in clinical use over the past decades, the diminished flow pulsatility generated by a fixed speed RBP has been regarded as a potential factor that may lead to adverse events such as vasculature stiffening and hemorrhagic strokes. In this study, we investigate the feasibility of generating physiological pulse pressure in the pulmonary circulation by modulating the speed of a right ventricular assist device (RVAD) in a mock circulation loop. A rectangular pulse profile with predetermined pulse width has been implemented as the pump speed pattern with two different phase shifts (0% and 50%) with respect to the ventricular contraction. In addition, the performance of the speed modulation strategy has been assessed under different cardiovascular states, including variation in ventricular contractility and pulmonary arterial compliance. Our results indicated that the proposed pulse profile with optimised parameters (Apulse = 10000 rpm and ωmin = 3000 rpm) was able to generate pulmonary arterial pulse pressure within the physiological range (9-15 mmHg) while avoiding undesirable pump backflow under both co- and counter-pulsation modes. As compared to co-pulsation, stroke work was reduced by over 44% under counter-pulsation, suggesting that mechanical workload of the right ventricle can be efficiently mitigated through counter-pulsing the pump speed. Furthermore, our results showed that improved ventricular contractility could potentially lead to higher risk of ventricular suction and pump backflow, while stiffening of the pulmonary artery resulted in increased pulse pressure. In conclusion, the proposed speed modulation strategy produces pulsatile hemodynamics, which is more physiologic than continuous blood flow. The findings also provide valuable insight into the interaction between RVAD speed modulation and the pulmonary circulation under various cardiovascular states.

Matched MeSH terms: Heart Ventricles/physiopathology*
Fulltext Ventricular dyssynchrony is common among heart failure patients with narrow QRS complex

Yaakob, Z.H., Syed Tamin, S., Nik Zainal, N.H., Chee, K.H., Chong, W.P., Hashim, N.E., et al.

JUMMEC, 2009;12(2):57-62.
MyJurnal

Current selection guideline for CRT uses broad QRS duration (>120 ms) as a marker for ventricular dyssynchrony. However, more recent data supports mechanical marker specifically measured by Tissue Doppler Imaging (TDI) as a better criterion to predict response to CRT. Sixty seven patients with significant left ventricular dysfunction (EF less than 40%) and narrow QRS complex were prospectively enrolled. They underwent Tissue Doppler Imaging (TDI) study to evaluate intraventricular mechanical dyssynchrony. Dyssynchrony index which is defined as standard deviation of time to peak systolic velocity in twelve ventricular segments was measured. A value greater than 32.6 is taken to reflect significant ventricular dyssynchrony. Overall 38 patients (56.7%) demonstrated significant dyssynchrony. There was no significant correlation between QRS duration and the Ts-SD-12 (r = 0.14, p = 0.11). Ventricular mechanical dyssynchrony is common in patients with normal QRS duration. Therefore, QRS duration alone will miss a substantial proportion of suitable patients for CRT and therefore deny them this adjunct therapy. We propose echocardiographic parameters, specifically TDI, to be included in patient selection criteria for CRT.

Matched MeSH terms: Heart Ventricles
Fulltext Sensitivity analysis of left ventricle with dilated cardiomyopathy in fluid structure simulation

Chan BT, Abu Osman NA, Lim E, Chee KH, Abdul Aziz YF, Abed AA, et al.

PLoS One, 2013;8(6):e67097.
PMID: 23825628 DOI: 10.1371/journal.pone.0067097

Dilated cardiomyopathy (DCM) is the most common myocardial disease. It not only leads to systolic dysfunction but also diastolic deficiency. We sought to investigate the effect of idiopathic and ischemic DCM on the intraventricular fluid dynamics and myocardial wall mechanics using a 2D axisymmetrical fluid structure interaction model. In addition, we also studied the individual effect of parameters related to DCM, i.e. peak E-wave velocity, end systolic volume, wall compliance and sphericity index on several important fluid dynamics and myocardial wall mechanics variables during ventricular filling. Intraventricular fluid dynamics and myocardial wall deformation are significantly impaired under DCM conditions, being demonstrated by low vortex intensity, low flow propagation velocity, low intraventricular pressure difference (IVPD) and strain rates, and high-end diastolic pressure and wall stress. Our sensitivity analysis results showed that flow propagation velocity substantially decreases with an increase in wall stiffness, and is relatively independent of preload at low-peak E-wave velocity. Early IVPD is mainly affected by the rate of change of the early filling velocity and end systolic volume which changes the ventriculo:annular ratio. Regional strain rate, on the other hand, is significantly correlated with regional stiffness, and therefore forms a useful indicator for myocardial regional ischemia. The sensitivity analysis results enhance our understanding of the mechanisms leading to clinically observable changes in patients with DCM.

Matched MeSH terms: Heart Ventricles/pathology*; Heart Ventricles/physiopathology*
The role of end-diastolic myocardial fibre stretch on infarct extension

Leong CN, Dokos S, Andriyana A, Liew YM, Chan BT, Abdul Aziz YF, et al.

Int J Numer Method Biomed Eng, 2020 01;36(1):e3291.
PMID: 31799767 DOI: 10.1002/cnm.3291

Myocardial infarct extension, a process involving the enlargement of infarct and border zone, leads to progressive degeneration of left ventricular (LV) function and eventually gives rise to heart failure. Despite carrying a high risk, the causation of infarct extension is still a subject of much speculation. In this study, patient-specific LV models were developed to investigate the correlation between infarct extension and impaired regional mechanics. Subsequently, sensitivity analysis was performed to examine the causal factors responsible for the impaired regional mechanics observed in regions surrounding the infarct and border zone. From our simulations, fibre strain, fibre stress and fibre stress-strain loop (FSSL) were the key biomechanical variables affected in these regions. Among these variables, only FSSL was correlated with infarct extension, as reflected in its work density dissipation (WDD) index value, with high WDD indices recorded at regions with infarct extension. Impaired FSSL is caused by inadequate contraction force generation during the isovolumic contraction and ejection phases. Our further analysis revealed that the inadequacy in contraction force generation is not necessarily due to impaired myocardial intrinsic contractility, but at least in part, due to inadequate muscle fibre stretch at end-diastole, which depresses the ability of myocardium to generate adequate contraction force in the subsequent systole (according to the Frank-Starling law). Moreover, an excessively stiff infarct may cause its neighbouring myocardium to be understretched at end-diastole, subsequently depressing the systolic contractile force of the neighbouring myocardium, which was found to be correlated with infarct extension.

Matched MeSH terms: Heart Ventricles/pathology; Heart Ventricles/physiopathology
Primary Arterial Switch Operation for Late Referral of Transposition of the Great Arteries with Intact Ventricular Septum in the Current Era: Do We Still Need a Rapid Two-Stage Operation?

Ota N, Sivalingam S, Pau KK, Hew CC, Dillon J, Latiff HA, et al.

World J Pediatr Congenit Heart Surg, 2018 01;9(1):74-78.
PMID: 29310554 DOI: 10.1177/2150135117743225

OBJECTIVE: We introduced primary arterial switch operation for the patient with transposition of great arteries and intact ventricular septum (TGA-IVS) who had more than 3.5 mm of posterior left ventricle (LV) wall thickness.
METHODS: Between January 2013 and June 2015, a total of 116 patients underwent arterial switch operation. Of the 116 patients, 26 with TGA-IVS underwent primary arterial switch operation at more than 30 days of age.
RESULTS: The age and body weight (mean ± SD) at the operation were 120.4 ± 93.8 days and 4.1 ±1.0 kg, respectively. There was no hospital mortality. The thickness of posterior LV wall (preoperation vs postoperation; mm) was 4.04 ± 0.71 versus 5.90 ± 1.3; P < .0001; interval: 11.8 ± 6.5 days. The left atrial pressure (mm Hg; postoperative day 0 vs 3) was 20.0 ± 3.2 versus 10.0 ± 2.0; P < .0001; and the maximum blood lactate level (mmol/dL) was 4.7 ± 1.4 versus 1.4 ± 0.3; P < .0001, which showed significant improvement in the postoperative course. All cases had delayed sternal closure. The patients who belonged to the thin LV posterior wall group (<4 mm [preoperative echo]: n = 13) had significantly longer ventilation time (days; 10.6 ± 4.8 vs 4.8 ± 1.7, P = .0039), and the intensive care unit stay (days) was 14 ± 9.2 versus 7.5 ± 3.5; P = .025, compared with thick LV wall group (≥4.0 mm: n = 13).
CONCLUSIONS: The children older than 30 days with TGA-IVS can benefit from primary arterial switch operation with acceptable results under our indication. However, we need further investigation for LV function.

Matched MeSH terms: Heart Ventricles/physiopathology; Heart Ventricles/surgery
Chest tube injury to left ventricle: complication or negligence?

Haron H, Rashid NA, Dimon MZ, Azmi MH, Sumin JO, Zabir AF, et al.

Ann Thorac Surg, 2010 Jul;90(1):308-9.
PMID: 20609810 DOI: 10.1016/j.athoracsur.2010.01.075

An injury to the left ventricle after a chest tube insertion is a rare but lethal phenomenon that is likely to occur if precautions are not seriously addressed. We present a 15-year-old girl who was diagnosed a left empyema thoracis. An attempt to place a chest drain in this young girl was almost fatal. A left ventricular repair together with thoracotomy and decortication were successful. This case emphasizes the rarity of this lethal complication and the importance of the correct technique for chest tube insertion.

Matched MeSH terms: Heart Ventricles/injuries*; Heart Ventricles/surgery
Congenital cyanotic heart disease with situs inversus totalis: an autopsy case report

Dayapala A, Kumar V

Am J Forensic Med Pathol, 2009 Jun;30(2):171-4.
PMID: 19465810 DOI: 10.1097/PAF.0b013e3181875a79

Sudden deaths because of congenital heart diseases are infrequently referred to the forensic pathologist for autopsy. Many of such deaths, if already diagnosed are released directly from the hospital without autopsy. Even forensic pathologists face a few difficulties in performing the autopsy on such infrequent cases, as they are not always updated with the anatomy of anomalies. While dealing with such cases, the concerned forensic pathologist is compelled to refer literature and textbooks again to understand the nature of developmental defects. This is especially so when dealing with cases of situs inversus accompanied by transposition of great arteries and other congenital cardiac abnormalities and variants such as single ventricle, double outlet right ventricle, Taussig-Bing variety etc. In the present case also, situs inversus with transposition of great vessels and other anomalies have been noted and studied.

Matched MeSH terms: Heart Ventricles/abnormalities; Heart Ventricles/pathology
Fulltext Effects of ageing on pro-arrhythmic ventricular phenotypes in incrementally paced murine Pgc-1β -/- hearts

Ahmad S, Valli H, Edling CE, Grace AA, Jeevaratnam K, Huang CL

Pflugers Arch., 2017 Dec;469(12):1579-1590.
PMID: 28821956 DOI: 10.1007/s00424-017-2054-3

A range of chronic clinical conditions accompany cardiomyocyte energetic dysfunction and constitute independent risk factors for cardiac arrhythmia. We investigated pro-arrhythmic and arrhythmic phenotypes in energetically deficient C57BL mice with genetic ablation of the mitochondrial promoter peroxisome proliferator-activated receptor-γ coactivator-1β (Pgc-1β), a known model of ventricular arrhythmia. Pro-arrhythmic and cellular action potential (AP) characteristics were compared in intact Langendorff-perfused hearts from young (12-16 week) and aged (> 52 week), wild-type (WT) and Pgc-1β -/- mice. Simultaneous electrocardiographic and intracellular microelectrode recordings were made through successive trains of 100 regular stimuli at progressively incremented heart rates. Aged Pgc-1β -/- hearts displayed an increased incidence of arrhythmia compared to other groups. Young and aged Pgc-1β -/- hearts showed higher incidences of alternans in both AP activation (maximum AP upshoot velocity (dV/dt)max and latency), recovery (action potential duration (APD90) and resting membrane potential (RMP) characteristics compared to WT hearts. This was particularly apparent at lower pacing frequencies. These findings accompanied reduced (dV/dt)max and increased AP latency values in the Pgc-1β -/- hearts. APs observed prior to termination of the protocol showed lower (dV/dt)max and longer AP latencies, but indistinguishable APD90 and RMPs in arrhythmic compared to those in non-arrhythmic hearts. APD restitution analysis showed that Pgc-1β -/- and WT hearts showed similar limiting gradients. However, Pgc-1β -/- hearts had shortened plateau AP wavelengths, particularly in aged Pgc-1β -/- hearts. Pgc-1β -/- hearts therefore show pro-arrhythmic instabilities attributable to altered AP conduction and activation rather than recovery characteristics.

Matched MeSH terms: Heart Ventricles/metabolism*; Heart Ventricles/physiopathology
Fulltext Infiltrative cardiac lymphoma with tricuspid valve involvement in a young man

Abdullah HN, Nowalid WK

World J Cardiol, 2014 Feb 26;6(2):77-80.
PMID: 24575174 DOI: 10.4330/wjc.v6.i2.77

Cardiac metastases are among the topics with limited systematic reviews. Theoretically, the heart can be infiltrated by any malignancy with the ability to spread to distant structures. Thus far, no specific tumors are known to have a predilection for the heart, but some do metastasize more often than others, for example, melanoma and primary mediastinal tumors. We report a case of cardiac metastasis from a diffuse large B cell lymphoma in a young man. The peculiarity of this case is that besides the involvement of right ventricle and atrium, the tricuspid valve was also infiltrated. Valvular metastasis is rarely reported in the medical literature.

Matched MeSH terms: Heart Ventricles
Recanalisation of the closed ductus arteriosus in a critically ill infant with transposition of the great arteries

Soo KW, Leong MC, Khalid F

Cardiol Young, 2016 Feb;26(2):371-4.
PMID: 26095661 DOI: 10.1017/S1047951115001055

We describe the case of an infant who was a late presenter of transposition of the great arteries where we proceeded with ductal stenting to improve oxygenation and left ventricle training. Stenting improved the infant's saturation while keeping the left ventricle well trained for 4 months after the procedure. This report demonstrates that intermediate-term left ventricle training can be achieved via ductal stenting.

Matched MeSH terms: Heart Ventricles

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