Current Cardiology Reviews - Volume 2, Issue 1, 2006

Coronary artery disease (CAD) remains a leading cause of death worldwide. In order to reduce the mortality from CAD, early detection and intervention prior to adverse events is likely to yield the most benefit. This however necessitates reliable prediction of high-risk patients. The current prediction schemes that incorporate traditional risk factors like hypertension and dyslipidemia are not very sensitive and improvements in risk stratification schemes are urgently needed. Pathophysiologically, CAD represents a spectrum of abnormalities starting from endothelial dysfunction to early fatty streaks, progressing to actual atherosclerotic plaque formation and subsequent stenosis. Detection of calcified plaques by electron beam computed tomography has been associated with a higher risk for coronary events. However, studies have shown that the rupture prone vulnerable plaques are composed of a thin fibrous cap with a large lipid pool; many of these plaques are non-calcified. The detection and characterization of non-calcified plaque is therefore of especial interest. Coronary multi-detector computed tomography (MDCT) can detect both calcified and non-calcified plaques and is emerging as a non-invasive tool that may significantly impact on how we detect and define high-risk population. MDCT provides a unique opportunity to study the natural history and response to therapy of coronary plaques. In this review, we discuss the use of MDCT to detect coronary plaques and its potential clinical implications.

Chronic kidney disease (CKD) is highly prevalent in patients with acute coronary syndromes (ACS) and is associated with poor outcomes. The clinical management of patients with CKD who develop ACS is problematic because of the lack of well-designed randomized trials assessing therapeutic strategies in such patients. The almost uniform exclusion of patients with CKD from randomized studies evaluating new targeted therapies for ACS, and concern about further deterioration of renal function and therapy-related toxic effects, may explain the less frequent use of proven medical therapies in this subgroup of high-risk patients. This could contribute to their excessive mortality. The objective of this review is to discuss the unresolved issues and uncertainties regarding recommended medical therapies and interventional strategies in CKD patients who develop an ACS.

Real-Time 3D echocardiography allows us to visualize every cardiac structure in any desired plane orientation, including the mitral valve. In this article we describe the recent advances in the assessment of the mitral valvular area and mitral valve anatomy by means of the use of Real-Time 3D echocardiography. Real-Time 3D echocardiography has been shown as a useful tool to evaluate those patients with rheumatic mitral stenosis. It provides accurate information regarding the mitral valvular area and mitral valvular score in this kind of patients. Furthermore, Real-Time 3D echocardiography could replace the classic method used as the gold standard for the quantification of the mitral valvular area: the Gorlin's method. In this work, the experience of the Cardiovascular Unit of the Hospital Clínico San Carlos in Madrid, Spain is presented.

Percutaneous mitral balloon valvuloplasty (MBV) was introduced in 1984 by Inoue who developed the procedure as a logical extension of surgical closed commissurotomy. Since then, MBV has emerged as the treatment of choice for severe pliable rheumatic mitral stenosis (MS). With increasing experience and better selection of patient, the immediate results of the procedure have improved and the rate of complications declined. When the reported complications of MBV are viewed in aggregate, complications occur at approximately the following rates: mortality (0% to 0.5%), cerebral accident (0.5% to 1%), mitral regurgitation (MR) requiring surgery (2% to 3%). These complication rates compare favorably to those reported after surgical commissurotomy. Several randomized trials reported similar hemodynamic results with MBV and surgical commissurotomy. Restenosis after MBV range from 4% to 70% depending on the patient selection, valve morphology and duration of follow up. Restenosis was encountered in 17.5% of the author's series and the 10-year restenosis free survival is 68% and is higher (78%) in patients with favorable mitral morphology. The 10-year event free survival is 80% and is higher (86%) in patients with favorable mitral morphology. The effect of MBV on severe pulmonary hypertension, concomitant severe tricuspid regurgitation, left ventricular function, left atrial size and atrial fibrillation will be addressed in the review. In addition, the application of MBV in specific clinical situations such as children, during pregnancy and for restenosis is discussed.

Percutaneous valve interventions is a rapidly evolving field of cardiovascular therapy. New technologies for aortic valve replacement and mitral valve repair are now developing in addition to the well established techniques of balloon valvuloplasty for the treatment of mitral and aortic stenosis. A number of devices are under development and investigation, and are going to be used in humans in the next few years to treat valve disease as an alternative to surgery in selected clinical conditions. Several clinical benefits are expected to be linked to the PVI as compared to conventional surgery: less pain and trauma for patients, shorter length of stay in the intensive care unit and hospital, and faster recovery from the procedure. As these techniques are less invasive, they will be potentially performed in an earlier stage of valve disease, when the clinical benefits are more probable. However, several demanding issues are going to challenge the dissemination of PVI in the next coming years, including: technology development and application, regulatory issues for new devices and new indications, training of the operators and development of the clinical applications for such therapies, evaluation of the results and comparison with the surgical standards. The present review focuses on the opportunities as well as on the hurdles of PVI, with the awareness that the exact role for these techniques has to be determined yet, and is strictly depending on the results of the ongoing clinical trials, which will become available in the next coming years.

Monitoring of Cardiac Output (CO) is of paramount importance in the critical patient. Established methods used to measure CO, such as oxygen Fick approach and thermodilution, are invasive and do not allow continuous monitoring. In addition, they are not reliable in the hemodynamically instable patient and suffer several technical drawbacks. Alternative methods are available, such as the Pulse Contour Method, but are dependent upon external calibration to evaluate cardiac activity. Recently, the Pressure Recording Analytical Method (PRAM) has been developed: it allows a more complete and detailed analysis of pressure morphology and "beat-to-beat" measurement of the stroke volume (SV) without external calibration. The basic principle of PRAM algorithm is the ability of detecting interactions between the cardiac and circulatory system, and therefore of calculating a new parameter, describing the work expenditure of cardiovascular system strictly correlated to SV, the Cardiac Cycle Efficiency (CCE). PRAM is becoming a promising alternative to traditional techniques, and may expand the potential applications of hemodynamic monitoring in clinical practice.

Despite significant progress in the prenatal diagnosis of congenital heart disease and the postnatal management, the prenatal evaluation of fetal heart function remains difficult. The unique characteristics of the fetal circulation have a significant impact on its cardiac function. Commonly used physiological concepts about the function of the heart can be misleading when applied to the intrauterine situation. Most noninvasive parameters of cardiac function are not validated in the fetus. In addition, unlike structural defects that can be easily confirmed after delivery, functional hemodynamic abnormalities diagnosed in utero cannot be verified postnatally with certainty as the neonatal circulation defers considerably from the fetal circulation. This review attempts to describe commonly used methods of assessment of fetal cardiac function, their physiological basis and, their utility in clinical practice.

In vitro models have proven themselves to be powerful allies with in vivo models for the dissection of the molecular mechanisms of cardiovascular development. The purpose of this manuscript is to review the advances that have enabled the creation of a new generation of in vitro models. These advances include the advent of new biomaterials and cell scaffolds that have provided the opportunity to design niches where developmental processes can occur under controlled, in vitro conditions. The engineering of biomaterials, along with new imaging capabilities, are being applied to important developmental questions. These interdisciplinary approaches promise to accelerate the identification of the molecular processes that regulate the cell-cell and cell-extracellular matrix (ECM) interactions that occur during the development of cardiac tissues. These new models not only offer the opportunity to test molecular mechanisms but also provide morphogenetic assays where the development of functional cardiovascular tissues can be achieved. The advent of these technologies is far reaching: from the ability to engineer functional cardiovascular tissues to the rational implantation of cell therapies for cardiovascular disease.

The development of a septated outflow is complicated, and insight into this process has been limited. However, our lab and others have recently described a secondary source of myocardium that adds to the lengthening outflow tract at later stages of development. Without the addition of this secondary heart field (SHF), the outflow is shortened and can not undergo the rotation necessary to make appropriate ventriculoarterial connections. Defects of outflow alignment such as tetralogy of Fallot and double outlet right ventricle may therefore be the result of problems with the addition of the secondary heart field. Moreover, the SHF adds a smooth muscle component to the outflow above the semilunar valves which may be necessary for proper insertion of the coronary stems into the aorta. This review will use the newly discovered SHF as well as other recent advances in the understanding of outflow development to shed light on the developmental pathology behind conotruncal defects.

Small animal models of heart failure have added invaluable information to advance diagnosis, pathophysiology and treatment of patients with heart failure, a growing epidemic in the western world. During the last decade, advances in small animal magnetic resonance imaging have contributed to this accumulating body of knowledge. In the review we give an overview about imaging techniques, their application to heart failure models in rats and mice, with focusing on providing practical information which will aid readers to acknowledge the opportunities offered by small animal MRI. We aim to provide this information as a useful guidance for developing imaging strategies and experimental protocols. In addition, theoretical background with respect to physics of imaging and pathophysiology of disease will be discussed. Techniques like cine, spin labeling perfusion, determination of regional blood volume by usage of intravascular contrast agents, myocardial motion encoding by phase mapping, coronary angiography, spectroscopic imaging, assessment of viability by late enhancement techniques will be described with specific applications in mind, such as phenotyping of the creatine kinase knock out mouse and assessment of myocardial mechanics and perfusion during remodeling after myocardial infarction.