Calcified plaque: the Achilles‘ Heel of present computed tomography coronary angiography for the elderly?

Nine percent to 27% of cardiac catheterizations today showed either angiographic normal coronary arteries or minimal atherosclerosis. Given the expense of cardiac catheterization and the desire to use this valuable resource for therapeutic rather than diagnostic purpose, there is a strong impetus to develop non-invasive means of accurately detecting significant coronary artery stenosis. Although echocardiography is the most common non-invasive cardiac procedure, nuclear     

Evaluation of non invasive methods for the diagnosis of atherosclerosis of the graft after orthotopic cardiac transplantation]

The frequency and severity of atherosclerosis of the cardiac transplant make it an essential complication of cardiac transplantation. Coronary angiography is the usual diagnostic method but it has severe limitations. In order to evaluate other diagnostic methods coronary angiography and non-invasive techniques: echocardiography, exercise stress ECG, exercise radionuclide ejection fraction, stress Thallium scintigraphy, were performed practically simultaneously in 60 patients after cardiac transplantation. These non-invasive methods were said to be positive in the presence of, respectively, a segmental wall motion abnormality, ischaemic ST segment depression, absence of increased ejection fraction on exercise, reversible or irreversible myocardial hypofixation. Coronary angiography was considered as the reference procedure for distinction between "normal coronary circulation" (no angiographically detectable lesion) and "graft atherosclerosis" (at least one coronary stenosis irrespective of the severity and extension). None of the non-invasive methods had an adequate sensibility when compared with coronary angiography (echocardiography 0.27, exercise stress ECG 0.28, exercise radionuclide ejection fraction 0.64, myocardial scintigraphy 0.62) or negative predictive value (echocardiography 0.56, exercise stress ECG 0.58, exercise radionuclide ejection fraction 0.68, myocardial scintigraphy 0.66). This inadequacy of the non-invasive technique may be explained by the fact that they are more adapted to the diagnosis of myocardial ischaemia than that of coronary studies. In addition, the extent of the coronary lesions may have masked discordance between 2 segments by the global hypovascularisation. The results of this study indicate that the non-invasive methods studied cannot be recommended for diagnosis of atherosclerosis of cardiac transplants.     

New findings and the role of cardiac imaging in myocarditis and related induced cardiomyopathy

IntroductionMyocarditis is an acquired primary cardiomyopathy due to viral inflammation. Despite the simplicity of this definition, the management, diagnosis, treatment as well the eventual evolution toward dilated cardiomyopathy (DCM) remains a problem in clinical practice. We review the role of genetic and non-invasive cardiac imaging techniques in myocarditis and related induced cardiomyopathy.ConclusionsThe most important non-invasive techniques in the diagnostic algorithm of myocarditis are 2D echocardiography and cardiac magnetic resonance. CMR represents the gold standard for its high sensibility, specificity and spatial resolution.     

Atrioventricular and interventricular delay optimization in cardiac resynchronization therapy: physiological principles and overview of available methods

In this review, the physiological rationale for atrioventricular and interventricular delay optimization of cardiac resynchronization therapy is discussed including the influence of exercise and long-term cardiac resynchronization therapy. The broad spectrum of both invasive and non-invasive optimization methods is reviewed with critical appraisal of the literature. Although the spectrum of both invasive and non-invasive optimization methods is broad, no single method can be recommend for standard practice as large-scale studies using hard endpoints are lacking. Current efforts mainly investigate optimization during resting conditions; however, there is a need to develop automated algorithms to implement dynamic optimization in order to adapt to physiological alterations during exercise and after anatomical remodeling.     

Determination of arterial impedance by non-invasive measurements

Most studies dealing with the arterial system impedance as resistance to blood ejection from the left ventricle are based on catheterization examinations of the aorta and the great arteries. The present work shows the possibility of using non-invasive approaches and describes one of them consisting in non-invasive determination of arterial impedance by measuring arterial pressure, cardiac output and the cardiac cycle phase structure. The results are compared with those of other studies.     

Correlation of the transaortic gradient determined with doppler echocardiography versus catheterization in patients with aortic stenosis]

The purpose of this report is to evaluate the reliability of a non-invasive estimation of a transaortic gradient in patients with valvular aortic stenosis by doppler echocardiography. We compared the transvalvular gradients obtained by cardiac catheterization (invasive) versus the estimation by non-invasive technique such as continuous-wave doppler in 30 consecutive patients with valvular aortic stenosis. When compared the peak velocity (Vmax) of the aortic jet versus the gradient obtained by cardiac catheterization we found a correlation coefficient (r) of 0.83 and when compared the gradient obtained by both methods we found an r value of 0.85. These results show that the calculations of aortic gradient by echo-doppler, are reliable. Besides this method allowed us to establish the correct diagnosis and to follow up these patients.     

Diagnostic value of magnetocardiography in coronary artery disease and cardiac arrhythmias: A review of clinical data

Despite the availability of several advanced non-invasive diagnostic tests such as echocardiography and magnetic resonance imaging, electrocardiography (ECG) remains as the most widely used diagnostic technique in clinical cardiology. ECG detects electrical potentials that are generated by cardiac electrical activity. In addition to electrical potentials, the same electrical activity of the heart also induces magnetic fields. These extremely weak cardiac magnetic signals are detected by a non-invasive, contactless technique called magnetocardiography (MCG), which has been evaluated in a number of clinical studies for its usefulness in diagnosing heart diseases. We reviewed the basic principles, history and clinical data on the diagnostic role of MCG in coronary artery disease and cardiac arrhythmias.     

Invasive hemodynamics of constrictive pericarditis, restrictive cardiomyopathy, and cardiac tamponade

Cardiac catheterization historically has been the principal diagnostic modality for the evaluation of constrictive pericarditis, restrictive cardiomyopathy, and cardiac tamponade. In many instances, the hemodynamic consequences of these disorders can be accurately delineated with non-invasive methods. However, cardiac catheterization should be considered when there is a discrepancy between the clinical and non-invasive imaging data, and particularly may be required for the evaluation of patients with complex hemodynamic disorders. This report describes the methods and clinical utility of invasive hemodynamic catheterization for the evaluation of constriction, restriction, and cardiac tamponade.     

Evaluation of the non-invasive localization accuracy of cardiac arrhythmias attainable by multichannel magnetocardiography (MCG)

The accuracy of multichannel magnetocardiography (MCG) for the non-invasive localization of cardiac arrhythmias was investigated. A non-magnetic catheter was used in phantom studies and for cardiac pacing of 6 patients. In a clinical setting, 32 patients with WPW-syndrome, 37 patients with premature ventricular complexes and 12 patients with ventricular tachycardia were studied and the MCG results compared to reference methods, including invasive electrophysiological mapping.Phantom and pacing studies demonstrated the spatial localization accuracy to be better than 15 mm for a dipole-to-dewar distance below 15 cm. In all patients with structural cardiac disease, the ectopic focus was localized at the margin of the damaged area, serving as a proof of MCG localization. Invasive mapping confirmed the MCG result whenever performed (42 patients). In 11 patients (9 WPW, 2 VT) the MCG localization result was verified by successful HF catheter ablation as a gold standard.MCG permits the non-invasive localization of cardiac arrhythmias with high spatial accuracy. MCG guided HF catheter ablation constitutes a new concept of non-invasive localization and minimally invasive causal therapy.     

Evaluation of prognosis after Q wave myocardial infarction. Comparison of invasive and noninvasive diagnostic strategies

The predictive value of several diagnostic strategies after myocardial infarction was assessed in 178 patients (mean age 55 +/- 9 years) treated medically after a primary Q wave myocardial infarction. Within 6 weeks of onset of symptoms the authors performed exercise stress test coupled with Thallium 201 scintigraphy, isotopic left ventriculography and conventional coronary angiography with ventriculography. The average left ventricular ejection fraction was 45 +/- 12%. Two non-invasive diagnostic strategies with and without results of scintigraphy and two invasive strategies with and without ventricular volumes were studied. The average follow-up period was 58 +/- 22 months. Sixteen cardiac deaths occurred. Multivariate Cox analysis showed that, in contrast to left ventricular volumes, coronary angiography did not provide additional prognostic value compared with the non-invasive model with Thallium scintigraphy and did not appear to be essential in terms of predictive value in this population. Moreover, the size of reversible defect on Thallium scintigraphy was an independent predictive factor of cardiac death and provided additional and independent prognostic information in the non-invasive and invasive strategies. Therefore, the reduction of residual ischaemia by coronary revascularisation could improve the long-term prognosis after myocardial infarction.     

PET imaging of cardiac hypoxia: opportunities and challenges

Myocardial hypoxia is a major factor in the pathology of cardiac ischemia and myocardial infarction. Hypoxia also occurs in microvascular disease and cardiac hypertrophy, and is thought to be a prime determinant of the progression to heart failure, as well as the driving force for compensatory angiogenesis. The non-invasive delineation and quantification of hypoxia in cardiac tissue therefore has the potential to be an invaluable experimental, diagnostic and prognostic biomarker for applications in cardiology. However, at this time there are no validated methodologies sufficiently sensitive or reliable for clinical use. PET imaging provides real-time spatial information on the biodistribution of injected radiolabeled tracer molecules. Its inherent high sensitivity allows quantitative imaging of these tracers, even when injected at sub-pharmacological (≥ pM) concentrations, allowing the non-invasive investigation of biological systems without perturbing them. PET is therefore an attractive approach for the delineation and quantification of cardiac hypoxia and ischemia. In this review we discuss the key concepts which must be considered when imaging hypoxia in the heart. We summarize the PET tracers which are currently available, and we look forward to the next generation of hypoxia-specific PET imaging agents currently being developed. We describe their potential advantages and shortcomings compared to existing imaging approaches, and what is needed in terms of validation and characterization before these agents can be exploited clinically.     

Risk of competitive sport in young athletes with heart disease

The majority of sudden deaths in young athletes occur in the context of underlying inherited or genetic cardiac disorders. The evaluation of every athlete regarding underlying cardiac disease is impractical and therefore needs to be targeted at those who are at a higher risk. A practical approach would be to channel efforts towards athletes with cardiac symptoms, those with a family history of inherited cardiac disease, and those with a family history of premature sudden death. There are potential pitfalls in the evaluation of young athletes using non-invasive tests when making the distinction between physiological adaptations to exercise and cardiac pathology. Physicians evaluating young athletes need to be aware of the spectrum of physiological adaptations and to be familiar with conditions responsible for sudden death in this population.     

Evaluation of myocardial contractility by the non-invasive method.

In evaluation of cardiac function by the non-invasive method, the possibility of separation of cardiac muscle performance from cardiac pump performance was studied. Among the non-invasive values, SV/ET, SV/(AO/EO), Pd/ICT, Pd/PEP, 1/ICT2, ET/PEP, and ET/ICT were considered as parameters for myocardial contractility. This research especially focused on Pd/ICT and ET/PEP. In auricular fibrillation it was possible to draw Starling-like curves and 3 dimensional coordinates to estimate a Vmax-like value. However this method could not be used in sinus rhythm. Whereas, in hypertension with abnormal afterload and uremia with abnormal preload, myocardial contractility was expressed by Pd/ICT under the influence of almost pure preload and ET/PEP under the influence of both preload and afterload. Therefore Pd/ICT was corrected with preload (AO/EO) and (Pd/ICT)/(AO/EO) may be used as the index for myocardial contractility.     

Heart valve surgery only after heart catheter study?

Recently British authors have postulated that in potential candidates for valvular surgery cardiac catheterization can be reserved for a minority of selected situations: when there is discrepancy between clinical and echocardiographic findings, when there is clinical evidence of a diseased ascending aorta and when there is clinical suspicion of coronary artery disease. In order that this manner of proceeding can be generally accepted two basic requirements must be fulfilled: First, in the majority of valvular patients, clinical examination and non-invasive tests including echocardiography, Doppler and radionuclide investigations should be sufficiently reliable not only to make a correct diagnosis but also to assess correctly the severity of the valvular lesion; second, the presence of significant coronary artery stenoses which would render necessary coronary artery bypass grafting in addition to valvular surgery would have to be excluded unequivocally by non-invasive means. In most instances severe valvular stenoses are correctly assessed by non-invasive means although misinterpretations may occur, such as in elderly patients with depressed cardiac output. In patients with moderately severe stenoses decision making based on non-invasive measurements as to whether valvular surgery should be carried out or not is much more difficult because of the limited accuracy of the non-invasive determination of valvular area (2D-echo) or pressure gradient (Doppler). Isolated massive valvular regurgitations can be quantitated by radionuclide angiography. Less severe regurgitations in combined lesions and regurgitations across both the mitral and the aortic valves however, cannot be quantitated by these techniques.(ABSTRACT TRUNCATED AT 250 WORDS)     

A noninvasive perspective of electrophysiologic testing

In this article, the author addresses the comparison between non-invasive and invasive approaches to detect and follow treatment of cardiac arrhythmias. Four major areas are discussed: determination of the mechanism of arrhythmias, arrhythmia diagnosis, defining the patient's risk from arrhythmia, and selection of therapy.     

Magnetocardiography: principles and potential uses in cardiology

Magnetocardiography (MCG) is a non-invasive technique of studying cardiac electrophysiology activity. It appears that electric and magnetic measurements are not only complementary but provide independent information. Described over 25 years ago, recent technical progress in the field of supraconductivity has provided MCG with real clinical applications. It is still mostly used in research, but its clinical applications are beginning to develop. The most interesting clinical application of the MCG is certainly its capacity to provide a non-invasive anatomical localisation of the arrhythmogenic substrate or of accessory pathways. Nowadays, however, the accuracy of these localisations needs to be improved. When this has been accomplished, MCG could play a significant role in non-invasive cardiological investigation with well-defined clinical applications.     

The use of non-invasive ventilation during acute respiratory failure due to pneumonia

The use of non-invasive ventilation in patients with community-acquired pneumonia is controversial since this is associated with high rates of treatment failure, compared with other causes of severe acute respiratory failure. The populations of patients with community-acquired pneumonia who have demonstrated better response to non-invasive ventilation are those with previous cardiac or respiratory disease, particularly chronic obstructive pulmonary disease. By contrast, the use of non-invasive ventilation in patients with community-acquired pneumonia without these pre-existing diseases should be very cautious and under strict monitoring conditions, since there are increasing evidences that the unnecessary delay in intubation of those patients who fail treatment with non-invasive ventilation is associated with lower survival. Pulmonary complications of immunosuppressed patients are associated with high rates of intubation and mortality. The use of non-invasive ventilation in these patients may decrease the need for intubation and improve the poor outcome associated with these complications. Continuous positive airway pressure has been used to treat acute respiratory failure in several conditions characterised by alveolar collapse. While this is extremely useful in patients with acute cardiogenic pulmonary oedema, the efficacy in pneumonia seems limited to immunosuppressed patients with pulmonary complications. Conversely, there are no sufficient evidences on the efficacy of continuous positive airway pressure in immunocompetent patients with pneumonia and severe acute respiratory failure.     

Serial Doppler echocardiographic assessment of left and right ventricular filling for non-invasive diagnosis of mild acute cardiac allograft rejection.

Detection of acute cardiac allograft rejection (AR) remains an important clinical challenge. The role of Doppler echocardiography for the non-invasive diagnosis of AR is controversial, in particular with regard to milder forms of rejection. This study was designed to evaluate the potential of Doppler echocardiography for the non-invasive diagnosis of mild AR. Serial measurements of left and right ventricular filling parameters were performed in 31 heart transplant recipients and compared with simultaneously obtained endomyocardial biopsies. To account for biological and technical variability, consecutive rejection-free studies were used to calculate 95% confidence limits for mitral and tricuspid maximum early flow velocity and pressure half time. Measurements obtained during mild AR were then compared to these data. The study demonstrated that all parameters varied considerably between consecutive rejection-free examinations. Changes in left and right ventricular filling parameters during mild AR rarely exceeded the calculated 95% confidence limits. Thus Doppler echocardiography appears of little value for the non-invasive diagnosis of mild acute cardiac rejection.     

Measurement of cardiac output by real-time 3D echocardiography in patients undergoing assessment for cardiac transplantation.

AIMS: Heart transplant assessment includes cardiac output calculation by right heart catheterisation. Real-time 3D echocardiography (RT-3DE), unlike 2D echocardiography, can measure stroke volume without inaccurate geometrical assumptions. The purpose of this study was to assess the feasibility and accuracy of non-invasive RT-3DE cardiac output calculation. METHODS AND RESULTS: Forty consecutive patients referred for transplant assessment underwent transthoracic RT-3DE. Full volume 3DE data sets were acquired from apical views with the iE33 ultrasound system (Philips Ultrasound, Bothell, USA). Four patients were excluded due to poor image quality. The remaining 36 patients had end-diastolic (LVEDV) and end-systolic (LVESV) left ventricular volumes manually traced, using endocardial detection software. Cardiac output was subsequently calculated: [(LVEDV - LVESV) x heart rate]. Thermodilution derived cardiac outputs, under the same haemodynamic conditions, were used as reference for comparison. There was close correlation between RT-3DE and catheter derived cardiac outputs (r = 0.91, y = 0.86x + 0.45, SEE 0.39 L/min, mean difference from reference -0.06 L/min, SD 0.40 L/min). RT-3DE data analysis took 3 min per case. CONCLUSION: This study shows RT-3DE is an accurate method for calculating cardiac output. In patients requiring serial evaluation of cardiac function, this non-invasive test may be preferable to invasive right heart catheterisation.     

The role of non-invasive methods in the diagnosis of heart failure

A survey is given on the validity of the non-invasive methods in the diagnostics of the cardiac insufficiency. Thereby the value of the echocardiography is emphasized not only in the etiologic clarification but also in the judgement of the cardiac (ventricular) function, the results of which can give the indication for invasive diagnostics in patients with cardiac insufficiency at stage III and IV NYHA. In the stages I and II NYHA of cardiac insufficiency this question and that one of the estimation of the functional capacity of the body are clarified by the use of tolerance tests. The ventriculography of radionuclides under conditions of exercise allows a far-reaching insight into the cardiac function, such as with the help of the parameter of the left ventricular ejection fraction.