Analog Models of The Circulation
Uri Dinnar in Cardiovascular Fluid Dynamics, 2019
This chapter focuses on the basic techniques of modeling of the circulatory system. From the early days of scientific study of the human circulation system, investigators found it easier to refer to an analog model rather than the real system, and use the analog model to explain the behavior of the human system under varying conditions. The real analogs of the circulatory system are the models which replace the real body compartment, like vessel walls, blood, and even the various other blood constituents by either mechanical or electrical analogies, whose constitutive relations are well established. The basic assumption in the Windkessel model is the linear relation between pressure and volume. In all of the analog models the left ventricle is replaced by a flow pump and the pressures within the analog system are obtained by the values of the various peripheral resistances.
The Heart as a Pump
Uri Dinnar in Cardiovascular Fluid Dynamics, 2019
This chapter discusses the heart, and especially the left ventricle, by considering its pumping activity. The heart, composed of two atria and two ventricles, is a combination of two synchronized pulsatile pumps in series. The performance of the heart can be measured and characterized by the use of various mechanisms that contribute to its function. In an attempt to find suitable parameters for left ventricular performance, cardiologists have moved from values that relate only to blood pressure in the systemic circulation to values that combine blood pressure in the ventricle and in the systemic circulation with volumes of blood pumped by the heart. The hydrodynamic parameters include both flow conditions, in both ventricles and the aorta, and flow characteristics, mainly velocity. When the mechanical descriptors used are force, velocity, and length, the underlying assumption is a unidimensional performance of the cardiac muscle.
Anomalies of the coronary arteries
Richard Jonas in Comprehensive Surgical Management of Congenital Heart Disease, 2004
Various abnormalities of the coronary arteries can be important complicating factors for a number of the congenital cardiac anomalies. For example, pulmonary atresia with intact ventricular septum is frequently complicated by coronary artery fistulas with or without coronary artery stenoses. Transposition of the great arteries can be complicated by unusual coronary ostial distribution and branching patterns. Patients with hypoplastic left heart syndrome who have the anatomical variant of aortic atresia with mitral stenosis also have a high incidence of coronary artery fistulas to the left ventricle. At least 5% of patients with tetralogy of Fallot have an anomalous anterior descending coronary artery arising from the right coronary artery. These various coronary problems are covered in the relevant chapters for the major anomaly. This chapter will focus on anomalies in which the coronary artery problem is the principal lesion.
Left ventricular wall stress compendium
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2012
Left ventricular (LV) wall stress has intrigued scientists and cardiologists since the time of Lame and Laplace in 1800s. The left ventricle is an intriguing organ structure, whose intrinsic design enables it to fill and contract. The development of wall stress is intriguing to cardiologists and biomedical engineers. The role of left ventricle wall stress in cardiac perfusion and pumping as well as in cardiac pathophysiology is a relatively unexplored phenomenon. But even for us to assess this role, we first need accurate determination of in vivo wall stress. However, at this point, 150 years after Lame estimated left ventricle wall stress using the elasticity theory, we are still in the exploratory stage of (i) developing left ventricle models that properly represent left ventricle anatomy and physiology and (ii) obtaining data on left ventricle dynamics. In this paper, we are responding to the need for a comprehensive survey of left ventricle wall stress models, their mechanics, stress computation and results. We have provided herein a compendium of major type of wall stress models: thin-wall models based on the Laplace law, thick-wall shell models, elasticity theory model, thick-wall large deformation models and finite element models. We have compared the mean stress values of these models as well as the variation of stress across the wall. All of the thin-wall and thick-wall shell models are based on idealised ellipsoidal and spherical geometries. However, the elasticity model's shape can vary through the cycle, to simulate the more ellipsoidal shape of the left ventricle in the systolic phase. The finite element models have more representative geometries, but are generally based on animal data, which limits their medical relevance. This paper can enable readers to obtain a comprehensive perspective of left ventricle wall stress models, of how to employ them to determine wall stresses, and be cognizant of the assumptions involved in the use of specific models.
Cardiac Hydatid Cyst in Left Ventricle
Published in Acta Chirurgica Belgica, 1998
S. Erentürk, B. Kocazeybek, A. Öner, B. Sönmez
Hydatid cyst of the heart is an uncommon lesion which usually develops in the left ventricle. A 34-year-old patient with hydatid cyst of the left ventricle, who was operated under cardiopulmonary bypass, is presented. Postoperative course at one year was uncomplicated.
Cardiac magnetic resonance detection of left ventricular thrombus in acute myocardial infarction
Published in Acute Cardiac Care, 2013
Chiara Lanzillo, Mauro Di Roma, Alessandro Sciahbasi, Monia Minati, Luciano Maresca, Gianluca Pendenza, Enrico Romagnoli, Francesco Summaria, Roberto Patrizi, Marco Di Luozzo, Paolo Preziosi, Ernesto Lioy, Francesco Romeo
Introduction: Left ventricular thrombosis (LVT) is a possible complication of acute myocardial infarction. Aim of our study was to evaluate incidence and clinical characteristics of patients with LVT after ST elevation myocardial infarction (STEMI) using contrast- enhanced magnetic resonance (CMR).Methods and Results: In a prospective cohort of 36 consecutive patients with STEMI acutely reperfused with primary percutaneous coronary intervention, CMR was performed within one week. LVT was found in 7 patients (19%), and was located in left ventricle apex or adherent to antero-septum. Compared to the rest of population patients with LVT have lower ejection fraction (38 ± 7% versus 51 ± 6%, P = 0.009), larger left ventricle end systolic volume (95.8 ± 19 ml versus 68.9 ± 19 ml, P = 0.02), higher time to reperfusion (9.3 ± 7.2 versus 5 ± 3.6, P = 0.03) and left anterior descending artery was constantly involved (100% versus 41 %, P = 0.06). In 5 cases the LVT was also detected by echocardiography, however, in 2 cases it was missed. Conclusions: The incidence of LVT after STEMI is not negligible and was accurately detected by CMR. Localization of myocardial infarction, time to reperfusion, ejection fraction and left ventricle end systolic volume are the most important predictors of left ventricle thrombus formation.