Myocardial Ischemia Evaluation With Dual-source Computed Tomography: Comparison With Magnetic Resonance Imaging

Introduction and objectives

Computed tomography does not accurately determine which coronary lesions lead to myocardial ischemia and consequently further tests are required to evaluate ischemia induction. The aim of this study was to compare diagnostic accuracy between dual-energy computed tomography and magnetic resonance imaging in the assessment of myocardial perfusion and viability in patients suspected of coronary artery disease.

Methods

A prospective study was performed in 56 consecutive patients (39 men [69.6%]; mean age [standard deviation], 63 [10]; range, 23-81). Computed tomography was performed with the following protocol: 1, adenosine stress perfusion; 2, coronary angiography; and 3, delayed enhancement. Magnetic resonance imaging for the evaluation of stress perfusion and delayed enhancement was performed within 30 days. Two observers in consensus analyzed the perfusion and delayed enhancement images.

Results

We studied 952 myocardial segments and 168 vascular territories. In a per-segment analysis, the sensitivity, specificity, and positive and negative predictive values of computed tomography compared with magnetic resonance were 76%, 99%, 89%, and 98% for perfusion defects, and 64%, 99%, 82%, and 99% for delayed enhancement, respectively. In a per-vascular territory analysis, the same measures were 78%, 97%, 86%, and 95% for perfusion defects, and 72%, 99%, 93%, and 97% for delayed enhancement, respectively. The mean radiation dose was 8.2 (2) mSv.

Conclusions

Dual-source computed tomography may allow accurate and concomitant evaluation of perfusion defects and myocardial viability and analysis of coronary anatomy.     

Puente miocárdico evaluado mediante tomografía computarizada multidetectores: posible causa del dolor torácico en pacientes más jóvenes con baja prevalencia de dislipemia

Introduction and objectives

The relationship between myocardial bridging and symptoms is still unclear. The purpose of our study was to assess the relationship between myocardial bridging detected by multidetector computed tomography and symptoms in a patient population with chest pain syndrome.

Methods

The study enrolled 393 consecutive patients wihout previous coronary artery disease studied for chest pain and referred to multidetector computed tomography between January 2007 and December 2010. Noninvasive coronary angiography was performed using multidetector computed tomography. Myocardial bridging was defined as part of a coronary artery completely surrounded by myocardium on axial and multiplanar reformatted images.

Results

Mean age was 64.6 (12.4) years and 44.8% were male. Multidetector computed tomography detected 86 myocardial bridging images in 82 of the 393 patients (20.9%). Left anterior descending was the most frequent coronary artery involved (87.2%). The prevalence of myocardial bridging was significantly higher in patients without significant atherosclerotic coronary stenosis on multidetector computed tomography (24.9% vs 15.0%; P = .02). Patients with myocardial bridging were younger (60.3 [13.8] vs 65.8 [11.9]; P<.001), had less prevalence of hyperlipidemia (29.3% vs 41.8%; P=.03), and more prevalence of cardiomyopathy (6.1% vs 1.6%, P=.02) compared with patients without myocardial bridging on multidetector computed tomography.

Conclusions

Multidetector computed tomography is an easy and reliable tool for comprehensive in vivo diagnosis of myocardial bridging. The results of the present study suggest myocardial bridging is the cause of chest pain in a subgroup of younger aged patients with less prevalence of hyperlipidemia and more prevalence of cardiomyopathy than patients with significant atherosclerotic coronary artery disease on multidetector computed tomography.Full English text available from:www.revespcardiol.org     

Diferencias en función de la gravedad de la atenuación pulmonar en varones con EPOC

Background and objetives

We compare the inspiratory and expiratory regional lung densities between different levels of COPD severity (as assessed by the GOLD scale and by the BODE index), and to assess the relationship between regional lung densities and functional lung parameters.

Patients and methods

Fifty-five stable moderate-severe COPD men were selected. Functional evaluation included dyspnoea scale, blood gases, spirometry, plethysmography, diffusing capacity and six-minute walk test. Severity was classified according the GOLD scale and the BODE index. High resolution computed tomography (HRCT) scans of the entire lung at full inspiration and two sections at full expiration were obtained. Densitometry software was used to calculate the densities of the lung areas.

Results

Inspiratory and expiratory mean lung densities (MLD) of the lower lobes were significantly lower in very severe and severe COPD patients than in moderate patients. In contrast, we only found differences between the upper lobe MLD values of moderate and severe COPD patients. Inspiratory and expiratory HRCT densities were similar among all BODE quartiles, for both the upper and lower lobes. In a multiple regression analysis, airway obstruction parameters were mainly related to the expiratory MLD of the lower lobes, whereas lung hyperinflation parameters were predicted by the inspiratory MLD of the lower lobes. Lastly, diffusion capacity was independently related to the expiratory/inspiratory MLD of the lower lobes and to the inspiratory MLD of the upper lobes.

Conclusions

There are differences in lung attenuation measurements by HRCT between the varying levels of COPD severity as assessed by the GOLD scale.     

Gated-SPECT de perfusión miocárdica como técnica complementaria de la resonancia magnética para pacientes con infarto de miocardio crónico

Introduction and objectives

The aim of this study was to compare magnetic resonance and gated-SPECT myocardial perfusion imaging in patients with chronic myocardial infarction.

Methods

Magnetic resonance imaging and gated-SPECT were performed in 104 patients (mean age, 61 [12] years; 87.5% male) with a previous infarction. Left ventricular volumes and ejection fraction and classic late gadolinium enhancement viability criteria (<75% transmurality) were correlated with those of SPECT (uptake >50%) in the 17 segments of the left ventricle. Motion, thickening, and ischemia on gated-SPECT were analyzed in segments showing nonviable tissue or equivocal enhancement features (50%-75% transmurality).

Results

A good correlation was observed between the 2 techniques for volumes, ejection fraction (P<.05), and estimated necrotic mass (P<.01). In total, 82 of 264 segments (31%) with >75% enhancement had >50% SPECT uptake. Of the 106 equivocal segments (50%-75% enhancement) on magnetic resonance imaging, 68 (64%) had >50% uptake, 41 (38.7%) had normal motion, 46 (43.4%) had normal thickening, and 17 (16%) had ischemic criteria on SPECT.

Conclusions

A third of nonviable segments on magnetic resonance imaging showed >50% uptake on SPECT. Gated-SPECT can be useful in the analysis of motion, thickening, and ischemic criteria in segments with questionable viability on magnetic resonance imaging.Full English text available from:www.revespcardiol.org/en     

Tuberculosis latente en la artritis reumatoide. Evaluación de la respuesta celular y tomografía computarizada de alta resolución

Introduction

The diagnosis of latent tuberculosis (LTB) in patients with rheumatoid arthritis (RA) has become important with the introduction of anti-tumor necrosis factor (anti-TNF-α) agents and the appearance of active tuberculosis cases in these patients. The tuberculin skin test (TST) has limited value in patients with RA. Tests based on the release of interferon-gamma (IFN-γ) are being studied, but their role has not been well established for this group of patients.

Objectives

To compare the diagnosis of LTB in patients with RA by using cellular immune response to the TST and T.SPOT-TB. Additionally, findings of tomography studies compatible with LTB were used.

Methods

Clinical evaluation, TST, T.SPOT-TB and high-resolution computed tomography (HRCT) in a group of patients with RA at the University Hospital of the Federal University of Goiás.

Results

Response to the TST was lower in patients with RA (13.5%) compared to the predicted values of the general population. T.SPOT-TB identified a higher number of patients with LTB than the TST (36.8%). HRCT showed changes compatible with LTB in 52.9% of the patients, including 8 of the 11 patients with negative TST and T.SPOT-TB.

Conclusions

The TST by itself is insufficient to diagnose LTB. A higher number of positive results were obtained with T.SPOT-TB when compared to the TST. Nevertheless, it was negative in a large percentage of patients with tomography findings consistent with LTB. HRCT is readily available in most large health-care centers and it could be incorporated into the diagnostic strategy for LTB in patients with RA.     

Valor pronóstico de la isquemia miocárdica y la necrosis en pacientes con la función ventricular izquierda deprimida: un registro multicéntrico con resonancia magnética cardiaca de estrés

Introduction and objectives

The incremental prognostic value of inducible myocardial ischemia over necrosis derived by stress cardiac magnetic resonance in depressed left ventricular function is unknown. We determined the prognostic value of necrosis and ischemia in patients with depressed left ventricular function referred for dipyridamole stress perfusion magnetic resonance.

Methods

In a multicenter registry using stress magnetic resonance, the presence (≥ 2 segments) of late enhancement and perfusion defects and their association with major events (cardiac death and nonfatal infarction) was determined.

Results

In 391 patients, perfusion defect or late enhancement were present in 224 (57%) and 237 (61%). During follow-up (median, 96 weeks), 47 major events (12%) occurred: 25 cardiac deaths and 22 myocardial infarctions. Patients with major events displayed a larger extent of perfusion defects (6 segments vs 3 segments; P <.001) but not late enhancement (5 segments vs 3 segments; P =.1). Major event rate was significantly higher in the presence of perfusion defects (17% vs 5%; P =.0005) but not of late enhancement (14% vs 9%; P =.1). Patients were categorized into 4 groups: absence of perfusion defect and absence of late enhancement (n = 124), presence of late enhancement and absence of perfusion defect (n = 43), presence of perfusion defect and presence of late enhancement (n = 195), absence of late enhancement and presence of perfusion defect (n = 29). Event rate was 5%, 7%, 16%, and 24%, respectively (P for trend = .003). In a multivariate regression model, only perfusion defect (hazard ratio = 2.86; 95% confidence interval, 1.37-5.95]; P = .002) but not late enhancement (hazard ratio = 1.70; 95% confidence interval, 0.90–3.22; P =.105) predicted events.

Conclusions

In depressed left ventricular function, the presence of inducible ischemia is the strongest predictor of major events.Full English text available from:www.revespcardiol.org/en     

Uso combinado de aspiración por punción transbronquial y tomografía computarizada de emisión fotónica única con Tc-2-metoxi-isobutil-isonitrilo para el diagnóstico de ganglios linfáticos mediastínicos agrandados

Background

To demonstrate the diagnostic accuracy of an integrated approach of blind trans-bronchial needle aspiration (TBNA) and ^99mTc-2-methoxy-isobutyl-isonitrile single photon emission computed tomography (^99mTc-MIBI-SPECT) in diagnosing mediastinal lymph adenopathy.

Methods

Sixty one consecutive patients with mediastinal lymph adenopathy undergoing both TBNA and ^99mTc-MIBI-SPECT were prospectively enrolled. Mediastinoscopy was attended in case of negative TBNA.

Results

Eighty three adenopathies were sampled (73 malignant and 10 benign). Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) of TBNA was 74%, 100%, 100%, and 34%, respectively; and of ^99mTc-MIBI-SPECT was 96%, 80%, 97%, and 73%, respectively. Combining TBNA and ^99mTc-MIBI-SPECT results sensitivity, specificity, PPV, NPV of 97%, 100%, 100%, and 83%, respectively, was obtained. TBNA alone avoided medistianoscopy in 65% of cases, while an integrated approach could have potentially obviated mediastinoscopy in 76%.

Conclusions

^99mTc-MIBI-SPECT improved the sensitivity and the NPV of TBNA, reducing the need of mediastinoscopy.     

Determinación de grupo de bajo riesgo para tener nódulos metastásicos no detectados por tomografía axial computarizada en la cirugía de las metástasis pulmonares

Introduction

In recent years, there has been debate regarding the diagnostic accuracy of computed tomography (CT) in the identification of lung metastases and the need for lung palpation to determine the number of metastatic nodules. The aim of this study was to determine in which patients the CT scan was more effective in detecting all metastases.

Methods

We studied all patients who underwent curative thoracotomy for pulmonary metastasis between 1998 and 2012. All cases were reviewed by two expert pulmonary radiologists before surgery. Statistical analyses were performed using Systat version 13.

Results

The study included 183 patients (63.6% male) with a mean age of 61.7 years who underwent 217 interventions. The CT scan was correct in 185 cases (85.3%). Discrepancies observed: 26 patients (11.9%) with more metastases resected than observed and 6 cases (2.8%) with fewer metastases. In patients with one or two metastases of colorectal origin or a single metastasis of any other origin, the probability of finding extra nodules was 9.5%. In the remaining patients, the probability was 27.8%, with statistically significant differences (P = .001). The mean age of the patients in whom no unobserved nodules were detected was 62.9 years compared to 56.5 years on average in patients who were free from any metastases (P = .001).

Conclusions

Patients older than 60 years, with one or two metastases of colorectal origin or a single metastasis from any other origin were considered to be the group with low probability of having more metastases resected than observed.     

Utilidad de la tomografía por emisión de positrones en la detección de metástasis ocultas extratorácicas en el carcinoma broncogénico no células pequeñas

Introduction

Positron emission tomography combined with computed axial tomography (PET/CT) is used for staging non small cell lung cancer (NSCLC). This study aims to describe PET/CT findings of unsuspected extrathoracic metastasis when used in mediastinal evaluation of patients with apparently resectable NSCLC.

Patients and method

Prospective and concurrent study including all NSCLC patients between June 2004 and November 2006 who underwent PET/CT after considering them as candidates for surgery, with resectable disease after bronchoscopy, thorax and abdominal CT, brain CT and bone gammagraphy evaluation, if metastasis at these locations were suspected. Metastasis were confirmed histopathologically or assumed when they had a compatible evolution.

Results

A total of 91 patients with NSCLC underwent PET/CT. In 24 of them (26%) at least one suspicious extrathoracic uptake was seen. In 7 patients (7.7%) those uptakes were NSCLC extrathoracic metastasis hidden from conventional staging. In 3 of these cases (13.1%) extrathoracic uptakes corresponded to metacrhonous tumours or pre-malignant conditions. Benign lesions were found in 12 patients (13.1%), and in 2 cases (2.2%) the uptake origins were undetermined.

Conclusions

PET/CT is a complementary diagnosis method for assessing hidden metastases which could modify the therapeutical approach in patients otherwise suitable for surgery.     

Cuantificación del área miocárdica en riesgo: validación de puntuaciones angiográficas coronarias con métodos de resonancia magnética cardiovascular

Introduction and objectives

Quantification of myocardial area-at-risk after acute myocardial infarction has major clinical implications and can be determined by cardiovascular magnetic resonance. The Bypass Angioplasty Revascularization Investigation Myocardial Jeopardy Index (BARI) and Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH) angiographic scores have been widely used for rapid myocardial area-at-risk estimation but have not been directly validated. Our objective was to compare the myocardial area-at-risk estimated by BARI and APPROACH angiographic scores with those determined by cardiovascular magnetic resonance.

Methods

In a prospective study, cardiovascular magnetic resonance was performed in 70 patients with a first successfully-reperfused ST-segment elevation acute myocardial infarction in the first week after percutaneous coronary intervention. Myocardial area-at-risk was obtained both by analysis of T2-short tau inversion recovery sequences and calculation of infarct endocardial surface area with late enhancement sequences. These results were compared with those of BARI and APPROACH scores.

Results

BARI and APPROACH showed a statistically significant correlation with T2-short tau inversion recovery for myocardial area-at-risk estimation (BARI, intraclass correlation coefficient=0.72; P<.001; APPROACH, intraclass correlation coefficient=0.69; P<.001). Better correlations were observed for anterior acute myocardial infarction than for other locations (BARI, intraclass correlation coefficient=0.73 vs 0.63; APPROACH, intraclass correlation coefficient=0.68 vs 0.50). Infarct endocardial surface area showed a good correlation with both angiographic scores (BARI, intraclass correlation coefficient=0.72; P<.001; with APPROACH, intraclass correlation coefficient=0.70; P<.001).

Conclusions

BARI and APPROACH angiographic scores allow reliable estimation of myocardial area-at-risk in current clinical practice, particularly in anterior infarctions.Full English text available from:www.revespcardiol.org     

Relación entre las calcificaciones ateroscleróticas en el tórax detectadas mediante tomografía computarizada y la función pulmonar

Background and objectives

A few recent epidemiological findings indicate a link between atherosclerosis and some lung functions. We studied further the relation between calcified chest atherosclerosis as seen in computed tomography (CT) and several lung functional parameters.

Patients and methods

Male construction workers originally screened for occupational lung cancer with CT had their chest atherosclerosis (aorta, the origins of its cervical branches, the coronary arteries and heart valves) visually classified. The relation between the atherosclerotic calcification scores and lung function (total lung capacity [TLC], forced expiratory volume in one second [FEV₁%], forced vital capacity [FVC%], maximal expiratory flow when 50% of FVC remains to be exhaled, total and specific diffusing capacities; all above expressed as percent of predicted value, and the FEV₁/FVC% ratio) were studied with the general linear model adjusted for smoking, exposure years for asbestos, and body mass index (n=432).

Results

All lung functions except TLC showed significant negative associations with calcifications in aorta and in its branches. TLC showed such association only with atherosclerosis in the ascending aorta.

Conclusions

Aortic atherosclerosis seems to be related with poor lung function. This may be due to deteriorated bronchial circulation, but other mechanisms can also be involved. Lung function poorer than would be expected due to pulmonary reasons may indicate aortic atherosclerosis.     

Integración de la imagen mecánica,estructural y eléctrica para entender la respuesta a la terapia de resincronización cardiaca

Introduction and objectives

There is extensive controversy exists on whether cardiac resynchronization therapy corrects electrical or mechanical asynchrony. The aim of this study was to determine if there is a correlation between electrical and mechanical sequences and if myocardial scar has any relevant impact.

Methods

Six patients with normal left ventricular function and 12 patients with left ventricular dysfunction and left bundle branch block, treated with cardiac resynchronization therapy, were studied. Real-time three-dimensional echocardiography and electroanatomical mapping were performed in all patients and, where applicable, before and after therapy. Magnetic resonance was performed for evaluation of myocardial scar. Images were postprocessed and mechanical and electrical activation sequences were defined and time differences between the first and last ventricular segment to be activated were determined. Response to therapy was defined as a reduction in left ventricular end-systolic volume ≥ 15% after 12 months of follow-up.

Results

Good correlation between electrical and mechanical timings was found in patients with normal left ventricular function (r² = 0.88; P = .005) but not in those with left ventricular dysfunction (r² = 0.02; P = not significant). After therapy, both timings and sequences were modified and improved, except in those with myocardial scar.

Conclusions

Despite a close electromechanical relationship in normal left ventricular function, there is no significant correlation in patients with dysfunction. Although resynchronization therapy improves this correlation, the changes in electrical activation may not yield similar changes in left ventricular mechanics particularly depending on the underlying myocardial substrate.Full English text available from: www.revespcardiol.org\en     

Etiological diagnosis of left ventricular dysfunction: computed tomography compared with coronary angiography and cardiac magnetic resonance

Introduction and objectives

To evaluate the capability of multidetector computed tomography to diagnose the coronary etiology of left ventricular dysfunction compared with using invasive coronary angiography and magnetic resonance.

Methods

Forty consecutive patients with left ventricular dysfunction of uncertain etiology underwent invasive coronary angiography and contrast magnetic resonance. All patients were evaluated with multidetector computed tomography including coronary calcium presence and score, noninvasive coronary angiography, and myocardial tissue assessment.

Results

The sensitivity and specificity of the presence of coronary calcium to identify left ventricular dysfunction was 100% and 31%, respectively. If an Agatston calcium score of >100 is taken, specificity increases to 58% with sensitivity still 100%. Sensitivity and specificity for coronary angiography by multidetector computed tomography was 100% and 96%, respectively; for identifying necrosis in contrast acquisition it was 57% and 100%, respectively; and in late acquisition, 84% and 96%, respectively. To identify coronary ventricular dysfunction with necrosis, the sensitivity and specificity was 92% and 100%, respectively.

Conclusions

Of all the diagnostic tools available in multidetector computed tomography, coronary angiography is the most accurate in determining the coronary origin of left ventricular dysfunction. A combination of coronary angiography and myocardial tissue study after contrast allows a single test to obtain similar information compared with the combination of invasive coronary angiography and contrast magnetic resonance.Full English text available from:www.revespcardiol.org     

Dismorfología de las deformidades de la pared torácica: distribución de frecuencias de los subtipos de pectus excavatum típico y subtipos poco comunes

Background/Purpose

More than forty percent of patients with pectus excavatum have a family history of chest deformity. However, no studies of the frequency of the different phenotypes of pectus excavatum have been published.

Methods

A random sample of 300 non-syndromic pectus excavatum patients, from the chest wall deformities clinic at Children's Hospital of The King's Daughters in Norfolk, Va., was studied and classified according to a previously described classification system. Photographs and computed tomography (CT) scans were utilized.

Results

Typical pectus excavatum. Photo data: localized deep depression (cup-shaped) deformity occurred in 67%; diffuse (saucer-shaped) 21%, trench-like (furrow-shaped) 10%, and Currarino-Silverman (mixed pectus excavatum/chondromanubrial carinatum) 1%. The deepest point was to the right of midline in 80%, left in 10% and central in 10%. By photo, the deepest point was in the lower sternum in 75%. When asymmetric, the deepest point of the deformity was to the right of midline in 90%. CT data: the average Haller index was 4.9. Severe sternal torsion (> 30 degrees) was associated with greater Haller index (6.3) than mild torsion (4.5). The deepest point of the depression was at the mid- or lower sternum in more than 99%. It proved impossible to estimate width or length of the depression because of poorly defined borders.

Conclusions

Typical PE is cup-shaped in 67% of cases, to the right of the midline in 80%, and involving the mid-to-lower sternum in 99%. However, other phenotypes, like the saucer and long trench, comprised one-third. Definition of the deformity is more reliable by CT scan.     

Coronary angiography by 16-slice computed tomography prior to valvular surgery

Introduction and objectives

Multislice computed tomography is an excellent technique for the detection of significant coronary artery lesions. Our purpose was to assess whether computed tomography could replace routine invasive coronariography before valvular surgery.

Methods

We studied 106 consecutive patients (mean age: 67 [10]): 76% aortic valvular disease (62% stenosis, 14% regurgitation), 20% mitral valvular disease (4% stenosis, 16% regurgitation), and 4% mitro-aortic disease. Non-invasive studies were performed by helical computed tomography. Eighty-four percent of patients were in sinus rhythm (40% using beta-blockers, 32% nitrates). Findings from both techniques were analyzed according to a predetermined segmented anatomical model of the coronary artery (a total of 1802 segments).

Results

The incidence of coronary artery disease in these patients was 30%. Using computed tomography, 96.8% of segments could be evaluated and 3.2% could not. Calcium score ranged from 0 to 7572 (median: 182). In the per patient analysis, computed tomography showed a sensitivity of 95%, specificity 94%, positive predictive value 84%, and negative predictive value 98%.

Conclusions

Computed tomography is an excellent technique for ruling out coronary lesions prior to valvular surgery, making an invasive study unnecessary if the quality of the study is good and the result is negative.Full English text available from: www.revespcardiol.org     

Valor pronóstico a largo plazo del análisis completo de los índices de resonancia magnética cardiaca tras un infarto de miocardio con elevación del segmento ST

Introduction and objectives

A variety of cardiac magnetic resonance indexes predict mid-term prognosis in ST-segment elevation myocardial infarction patients. The extent of transmural necrosis permits simple and accurate prediction of systolic recovery. However, its long-term prognostic value beyond a comprehensive clinical and cardiac magnetic resonance evaluation is unknown. We hypothesized that a simple semiquantitative assessment of the extent of transmural necrosis is the best resonance index to predict long-term outcome soon after a first ST-segment elevation myocardial infarction.

Methods

One week after a first ST-segment elevation myocardial infarction we carried out a comprehensive quantification of several resonance parameters in 206 consecutive patients. A semiquantitative assessment (altered number of segments in the 17-segment model) of edema, baseline and post-dobutamine wall motion abnormalities, first pass perfusion, microvascular obstruction, and the extent of transmural necrosis was also performed.

Results

During follow-up (median 51 months), 29 patients suffered a major adverse cardiac event (8 cardiac deaths, 11 nonfatal myocardial infarctions, and 10 readmissions for heart failure). Major cardiac events were associated with more severely altered quantitative and semiquantitative resonance indexes. After a comprehensive multivariate adjustment, the extent of transmural necrosis was the only resonance index independently related to the major cardiac event rate (hazard ratio=1.34 [1.19-1.51] per each additional segment displaying >50% transmural necrosis, P<.001).

Conclusions

A simple and non-time consuming semiquantitative analysis of the extent of transmural necrosis is the most powerful cardiac magnetic resonance index to predict long-term outcome soon after a first ST-segment elevation myocardial infarction.Full English text available from: www.revespcardiol.org/en     

Evaluación de la complejidad de la activación miocárdica durante la fibrilación ventricular. Estudio experimental

Introduction and objectives

An experimental model is used to analyze the characteristics of ventricular fibrillation in situations of variable complexity, establishing relationships among the data produced by different methods for analyzing the arrhythmia.

Methods

In 27 isolated rabbit heart preparations studied under the action of drugs (propranolol and KB-R7943) or physical procedures (stretching) that produce different degrees of change in the complexity of myocardial activation during ventricular fibrillation, use was made of spectral, morphological, and mapping techniques to process the recordings obtained with epicardial multielectrodes.

Results

The complexity of ventricular fibrillation assessed by mapping techniques was related to the dominant frequency, normalized spectral energy, signal regularity index, and their corresponding coefficients of variation, as well as the area of the regions of interest identified on the basis of these parameters. In the multivariate analysis, we used as independent variables the area of the regions of interest related to the spectral energy and the coefficient of variation of the energy (complexity index=–0.005×area of the spectral energy regions –2.234×coefficient of variation of the energy+1.578; P=.0001; r=0.68).

Conclusions

The spectral and morphological indicators and, independently, those derived from the analysis of normalized energy regions of interest provide a reliable approach to the evaluation of the complexity of ventricular fibrillation as an alternative to complex mapping techniques.Full English text available from:www.revespcardiol.org/en.     

Eco-Doppler de ejercicio en pacientes con miocardiopatía hipertrófica. Factores determinantes de la limitación funcional

Introduction and objectives

At-rest echocardiography is a poor predictor of exercise capacity in patients with hypertrophic cardiomyopathy. We aimed to test the performance of treadmill exercise Doppler echocardiography in the prediction of functional limitations in these patients.

Methods

Eighty-seven consecutive patients with hypertrophic cardiomyopathy underwent treadmill exercise echocardiography with direct measurement of oxygen consumption. Both at rest and at peak exercise, the mitral inflow, mitral regurgitation, left ventricular outflow tract obstruction and mitral annulus velocities were assessed.

Results

Forty-three patients developed left ventricular outflow tract obstruction during exercise, which significantly decreased oxygen consumption (21.3 [5.7] mL/kg/min vs 24.6 [6.1] mL/kg/min; P=.012), and had greater left atrial volume (42.1 [14.5] mL/m² vs 31.1 [11.6] mL/m²; P<.001) and a higher degree of mitral regurgitation and E/E’ ratio during exercise. Exercise variables improved the predictive value of functional capacity (adjusted R² rose from 0.38 to 0.49). Independent predictors of oxygen consumption were age, left atrial volume, E/E’ ratio and the presence of left ventricular outflow tract obstruction. In a subset of patients without left ventricular outflow obstruction, only left ventricular and atrial volume indexes were independent predictors of exercise capacity.

Conclusions

In patients with hypertrophic cardiomyopathy, left ventricular outflow tract obstruction and left atrial volume are the main predictors of exercise capacity. Exercise echocardiography is a better predictor of functional performance than at-rest echocardiography, although its predictive power is under 50%. In nonobstructed patients, left atrial and ventricular volumes were the independent factors.Full English text available from:www.revespcardiol.org/en     

Utilidad de la videotoracoscopia para una correcta estadificación de tumores T3 por invasión de pared

Background

Exploratory video-assisted thoracoscopy (EVT) can be used to assess the resectability of lung carcinomas. The aim of this study was to investigate the usefulness of this technique for distinguishing between tumors that invade the chest wall and should be staged as T3 and tumors that have been incorrectly staged as T3 on the basis of imaging studies.

Patients and Methods

From March 1993 through December 2007, we studied 1277 patients, of whom 150 (137 men and 13 women; age range, 28–81 years) presented tumors classified as cT3 because of chest wall invasion on the basis of imaging studies.

Results

After exploratory EVT, 44 pT3 tumors with chest wall invasion were confirmed intraoperatively and by histopathology. Of these, 36 had been correctly classified as cT3 by computed tomography or magnetic resonance imaging. However, tumors had been understaged as cT2 in 6patients and overstaged as cT4 in 2 patients. The sensitivity, specificity, and positive and negative predictive values obtained were 100%.

Conclusions

We believe that exploratory EVT is clearly better than computed tomography and/or magnetic resonance imaging for detecting chest wall invasion. In addition to correctly staging a tumor as T3 because of chest wall invasion, the technique can also help decide the best surgical approach in each case.     

Estudio tractográfico de la anatomía helicoidal del miocardio ventricular mediante resonancia magnética por tensor de difusión

Introduction and objectives

Deeper understanding of the myocardial structure linking the morphology and function of the heart would unravel crucial knowledge for medical and surgical clinical procedures and studies. Several conceptual models of myocardial fiber organization have been proposed but the lack of an automatic and objective methodology prevented an agreement. We sought to deepen this knowledge through advanced computer graphical representations of the myocardial fiber architecture by diffusion tensor magnetic resonance imaging.

Methods

We performed automatic tractography reconstruction of unsegmented diffusion tensor magnetic resonance imaging datasets of canine heart from the public database of the Johns Hopkins University. Full-scale tractographies have been built with 200 seeds and are composed by streamlines computed on the vector field of primary eigenvectors at the diffusion tensor volumes. We also introduced a novel multiscale visualization technique in order to obtain a simplified tractography. This methodology retains the main geometric features of the fiber tracts, making it easier to decipher the main properties of the architectural organization of the heart.

Results

Output analysis of our tractographic representations showed exact correlation with low-level details of myocardial architecture, but also with the more abstract conceptualization of a continuous helical ventricular myocardial fiber array.

Conclusions

Objective analysis of myocardial architecture by an automated method, including the entire myocardium and using several 3-dimensional levels of complexity, reveals a continuous helical myocardial fiber arrangement of both right and left ventricles, supporting the anatomical model of the helical ventricular myocardial band described by F. Torrent-Guasp.Full English text available from:www.revespcardiol.org/en