Clinical Cases In Cardiology
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Students, cardiologists and allied professionals wishing to refresh their clinical skills can practise with real-case scenarios to test their knowledge. You can also share your experience by submitting a clinical case.
These cases present real and typical clinical scenarios that are followed, managed and discussed in light of current ESC recommendations. They usually focus on one central topic, although a case will often touch on several fields in cardiology, illustrating multiple issues and guidelines.
Journal of Cardiology Cases (JC Cases) is an official peer-reviewed online journal of the Japanese College of Cardiology (JCC) dedicated to case reports. JC Cases provides an appropriate forum for all cardiologists by publishing without delay their important clinical cases of recent occurrence. Notable articles are also discussed in the journal's editorials. One year after their publication, all articles become accessible, at no cost, also to nonsubscribers.
Brian Case, MD, FACC, joined the cardiology team at MedStar Southern Maryland Hospital Center in August 2021 as an Interventional Cardiologist and member of the MedStar Heart & Vascular Institute. He is board certified in interventional cardiology, cardiovascular disease and internal medicine with extensive fellowship training.
The review included only cases using fourth-generation cryoballoon catheters or contact force-sensing radiofrequency catheters. The endpoints for the study were total procedural duration from groin access until end of case and total fluoroscopy time.
Time-varying elastance models can simulate only the pressure and volume signals in the heart chambers while the diagnosis of clinical cases and evaluation of different treatment techniques require more information. In this study, an extended model utilizing the geometric dimensions of the heart chambers was developed to describe the cardiac function. The new cardiac model was evaluated by simulating a healthy and dilated cardiomyopathy (DCM) condition for adults and children. The left ventricular ejection fraction, end-diastolic volume, end-diastolic diameter and diastolic sphericity index were 53.60%, 125 mL, 5.08 cm and 1.82 in the healthy adult cardiovascular system model and 23.70%, 173 mL, 6.60 cm and 1.40 in the DCM adult cardiovascular system model. In the healthy child cardiovascular system model, the left ventricular ejection fraction, end-diastolic volume, end-diastolic diameter and diastolic sphericity index were 59.70%, 92 mL, 4.10 cm and 2.26 respectively and 30.70%, 125 mL, 4.94 cm and 1.87 in the DCM child cardiovascular system model. The developed cardiovascular system model simulates the hemodynamic variables and clinical diagnostic indicators within the physiological range for healthy and DCM conditions proving the feasibility of this new model to evaluate clinical cases in adults and children.
Numerical modeling of cardiac physiology plays an important role to evaluate clinical scenarios and outcomes of different treatment techniques before experimental or clinical applications. Nonetheless, the information obtained from a numerical simulation depends on the modeled relations in the utilized model. For instance, time-varying elastance models describe the pressure-volume relations in the heart chambers using an elastance function which changes with respect to time over a cardiac cycle [1]. The time-varying elastance models have been used for different clinical scenarios such as evaluating heart failure [2], left ventricular assist device support [3] or simulating the interaction between the cardiovascular and respiratory systems [4,5]. Although time-varying elastance models are widely used to model the cardiac function, they simulate only the blood pressure and volume in heart chambers.
More detailed numerical models such as single fiber contraction models describe the cardiac function by simulating the contraction of a sarcomere over a cardiac cycle [6]. The single fiber contraction models allow simulating the fiber tension in a heart chamber, in addition to the blood pressure and volume [7]. The single fiber contraction models have also been used to simulate physiological and clinical scenarios such as the influence of intra-myocardial pressure on the coronary arterial blood flow rate [8], simulation of fetal heart rate variability [9] or evaluation of rotary blood pump support [10] etc. Although these models are driven by the fiber contraction and provide more information about the cardiac physiology, they also remain insufficient to simulate different mechanisms occurring at each level of cardiac contraction and do not provide information about clinical indicators such as heart chamber dimensions for the physiological cases.
Multi-scale models of the cardiac dynamics simulating the physiological processes at the cellular, protein and organ levels also were developed and used to understand the pathophysiology of heart failure [11]. However, increasing the complexity of a numerical model may not improve the outcome of a simulation. As shown in [12] relatively simple models describing the cardiac function, simulate the physiological and clinical cases such as heart failure and mechanical circulatory support more accurately with respect to the multiscale models because the small discrepancies between the real physiology and the numerical model in each scale cause large deviations at the organ level. Moreover, lumped parameter modeling mostly was used to simulate the adult cardiovascular system. Numerical simulation of cardiac function in children remains to work further to evaluate different physiological scenarios as only a small number of studies focus on pediatric cases [13]. A detailed review of lumped parameter models is given in [14].
The similarities and differences between children and adult physiologies have been subject to developmental theories [15]. Hemodynamic parameters and size of the heart in children reaches similar values of the adult cardiovascular system in time. Therefore, a numerical model capable of simulating the dimensions of the heart chambers and related parameters used to diagnose clinical cases and describe the cardiac function not only for adults but also for children can be utilized to evaluate clinical cases and effects of different treatment in pediatric patients at different ages.
The aim of this study is to develop a lumped parameter model describing the cardiac function and circulatory system and simulating the diagnostic criteria for the clinical cases, therefore, can be used to evaluate physiological scenarios and treatment techniques for cardiovascular system diseases in adults and children at different ages.
The left ventricular and aortic systolic pressures decreased in the DCM cases for the adult and child cardiovascular system models. The left ventricular volume increased significantly simulating the enlargement because of the impaired contractility in the DCM left ventricles. Left atrial volumes in DCM models increased with respect to the left atrial volumes in the healthy cardiovascular system models. The left ventricular and atrial diameters increased as well with the increased volumes in the left atria and ventricles of the adult and child DCM cardiovascular system models. The pressure-volume loops for the healthy and DCM models are given in Fig 4.
Time-varying elastance models reveal only the relationship between the pressure and volume signals in the ventricles by lumping all the contraction dynamics in the elastance term over a cardiac cycle. These models have been widely used to evaluate clinical devices or clinical scenarios numerically despite their limited capability [30,40]. The cardiovascular system model proposed in this study describes the relationship between pressure and dimensions of the heart chambers. Also, systolic elastances were used to describe pressures in the ventricle models. Therefore, the proposed numerical model extends the capability of the existing relatively simple time-varying elastance models without losing information. Single fiber contraction models are driven by contraction of muscle fibers, and they simulate length and tension on the fibers, along with the pressure and volume relation in heart chambers. Although single fiber contraction models have not been used as widely as the time-varying elastance models, they have been utilized to evaluate medical devices numerically [7,41]. These models also have limited capabilities in simulating indicators for clinical scenarios as ejection fraction is the only clinical indicator can be obtained. Therefore, their capability also remains limited with respect to the developed cardiovascular system model in this study. Multiscale models simulating the action potentials and Calcium kinetics provide detailed information about the cardiac dynamics at cellular and protein levels for a healthy and DCM heart [11]. However, at the organ level ejection fraction is the only parameter that such models can provide. Moreover, calcium dynamics in children at early ages are quite different [42], therefore, substantial modifications in the equations may be required to simulate heart failure when these models are used to simulate children cardiovascular system. The developed cardiovascular system model simulates cardiac function at organ level and allows simulation of additional clinical indicators such as sphericity index and fractional shortening, which are used in the diagnosis of heart failure. Moreover, the presented cardiovascular system model shows that children have a relatively long longitudinal axis with respect to the minor axis in their left ventricle.
Mitral regurgitation may occur in DCM because increased left ventricular size cause improper leaflet coaptation [38]. Simulation of the regurgitant flow rate through the mitral valve requires a numerical model describing the motion of leaflets [10,17] or zener diode analogue models allowing reverse blood flow. Flow rate signals through the heart valves were simulated using ideal diodes in the developed cardiovascular system model. Therefore, the change of the volume signals in the heart chambers depends only forward flow rate signals. Utilizing an elaborated mitral valve model will allow simulating effects regurgitant flow rate on the left ventricular function as the change of the left ventricular volume signal depends on mitral and aortic valve flow rates regardless of the direction of the blood flow (Eq 4). Nonetheless, ideal diode models have also been used widely to simulate clinical scenarios such as DCM and LVAD therapies in cardiovascular system [76,77]. 59ce067264
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