Protocolo Bruce: errores habituales en la evaluación de la capacidad funcional y en el diseño de un entrenamiento físico en cardiopatía isquémica / Bruce protocol: common errors in the evaluation of functional capacity and in exercise prescription in ischemic heart disease

Introducción. La utilización de pruebas de esfuerzo con incrementos bruscos en la carga de trabajo puede acentuar la pérdida de relación lineal entre el VO2 y la frecuencia cardíaca. La falta de datos objetivos para considerar la frecuencia cardíaca como máxima puede ocasionar aplicaciones de intensidades de trabajo insuficientes durante los entrenamientos. Objetivos. Determinar la variabilidad de la capacidad funcional y de la frecuencia cardíaca máxima, realizando en un mismo paciente una prueba de esfuerzo indirecta y directa. Determinar la intensidad de entrenamiento óptima con una prueba de esfuerzo indirecta. Métodos. Veintinueve pacientes con cardiopatía isquémica realizaron, en un plazo inferior a 4 semanas, una prueba de esfuerzo indirecta (protocolo Bruce) y una directa (ergoespirometría). Se analizaron parámetros de trabajo, metabólicos y cardíacos. Resultados. Objetivamos una sobrestimación de la capacidad funcional con el protocolo Bruce del 10,4%. La frecuencia cardíaca máxima fue de 125 lpm en el protocolo Bruce y de 132 lpm en la ergoespirometría. Los umbrales aerobio/anaerobio se produjeron a 99 y 119 lpm. La intensidad de entrenamiento diseñada a partir del protocolo Bruce y según el método de 75-85% de la frecuencia cardíaca máxima fue de 95 vs. 107 lpm. Utilizando el método Karvonen al 60-80% fue de 103 vs. 113 lpm. Conclusiones. La capacidad funcional está sobrestimada con la utilización del protocolo Bruce estandarizado. El diseño de un entrenamiento en función de porcentajes de frecuencia cardíaca puede hacernos trabajar de una forma submáxima. La metodología de Karvonen estima la intensidad de trabajo de una manera más óptima(AU)

Introduction. The use of stress tests with sudden increases in the workload may accentuate the loss of the linear relationship between VO2 and heart rate. Lack of objective data to consider heart rate as maximum may result in the application of submaximum workloads during exercise training. Objectives. To determine variability in functional capacity and maximum heart rate by means of an indirect and direct exercise test in the same patient. To determine optimum training intensity using an indirect stress test. Methods. In a period under 4 weeks, 29 patients with ischemic heart disease performed an indirect exercise test (Bruce protocol) and a direct exercise test (ergospirometry). Work, metabolic and cardiac parameters were analyzed. Results. We observed an overestimation of functional capacity with the Bruce protocol of 10.4%. Maximum heart rate was 125 bpm in the Bruce protocol and 132 bpm in the ergospirometry test. Aerobic and anaerobic thresholds occurred at 99 vs 119 bpm, respectively. Workload intensity designed according to the Bruce Protocol and in accordance with the 75-85% maximum heart rate method was 95 vs 107 bpm. This was 103 vs 113 bpm with the Karvonen method at 60 - 80%. Conclusions. Functional capacity is overestimated when the standardized Bruce protocol is used. The design of training based on heart rate percentages may cause us to work submaximally. The Karvonen method estimates work load more optimally (AU)

Entrenamiento interválico en pacientes con cardiopatía isquémica: metodología y análisis de resultados ergoespirométricos / Interval training in patients with coronary artery disease: methodology and ergospirometric data analysis

Introducción. El ejercicio de tipo interválico es una modalidad de entrenamiento poco utilizada en pacientes con cardiopatía isquémica aunque sus beneficios fisiológicos han sido demostrados por distintos autores. Objetivo. Describir un método sencillo de entrenamiento interválico, así como evaluar los beneficios y la seguridad del mismo en pacientes con cardiopatía isquémica. Método. Se estudiaron 25 pacientes con cardiopatía isquémica estable que realizaron un entrenamiento interválico de alta intensidad en cicloergómetro. Para programar la intensidad del entrenamiento se realizó un Steep Ramp Test. El entrenamiento consistió en intervalos de 20 s al 50% de la carga máxima alcanzada en el Steep Ramp Test, seguido de intervalos de 40 s al 10% de la misma. Se realizó una ergoespirometría sobre cicloergómetro pre y posprograma para comparar resultados. Resultados. Tras 8 semanas de entrenamiento se produjeron incrementos significativos en el VO2pico (19,9 ± 5,3 vs. 23,8 ± 6ml/kg/min), en la carga máxima (103,5 ± 42,6 vs. 124,6 ± 53,4 vatios), en la frecuencia cardíaca (FC) máxima (117,6 ± 15,7 vs. 128 ± 16,5 lat./min) y en el índice de recuperación de la FC en el primer minuto (16,5 ± 9,2 vs. 21,3 ± 7,7 lat./min). No se registraron efectos adversos. Conclusión. El ejercicio interválico de alta intensidad es una modalidad de entrenamiento sencilla y segura que permite mejorar de forma significativa el VO2pico y la tolerancia al ejercicio en pacientes con cardiopatía isquémica (AU)

Background. Interval training is an exercise modality underused in patients with coronary artery disease even though different authors have shown its physiological benefits. Objective. To describe a simple method of interval training and to evaluate its benefits and safety in patients with coronary artery disease. Method. Twenty-five patients with stable coronary artery disease underwent high-intensity interval training on a cycle ergometer. To determine the training work rate, we performed a steep ramp test. The training consisted of intervals of 20seconds at 50% of the maximum load achieved in the steep ramp test, followed by intervals of 40seconds at 10%. A cycle ergospirometry was performed before and after the programme to compare data. Results. After 8 weeks of interval training, there were significant gains in V02 peak (19.9±5.3 vs. 23.8±6mL·kg-1·min−1), maximal work rate (103.5±42.6 vs.124.6±53.4 watts), maximal heart rate (117.6±15.7 vs. 128±16.5 bpm) and heart rate recovery index in the first minute (16.5±9.2 vs. 21.3±7.7 bpm). There were no adverse events. Conclusion. In patients with coronary artery disease, high-intensity interval training is an easy, safe exercise modality that produces improvement in VO2 peak and exercise tolerance (AU)

[The value of cardiac troponin I as diagnostic test in the study of chest pain]. / Valor de la troponina I cardíaca como prueba diagnóstica en el estudio del dolor torácico.

BACKGROUND AND OBJECTIVES: Cardiac troponin I is a highly sensitive and specific myocardial injury marker. We have analyzed the use of cardiac troponin I values in the diagnosis of coronary artery disease, in previously healthy patients who developed chest pain with inconclusive analytical and ECG diagnostic findings. PATIENTS, MATERIAL AND METHODS: A one year cross-sectional consecutive study was conducted, in a total of 37 patients with no previously known heart disease who were admitted to the coronary unit for suspected anginal chest pain with normal cardiac enzymes and ECG. Abnormal cardiac troponin I levels at admission were defined as > or = 0.4 ng/ml, and were compared with coronary angiography or exercise test results and related to the duration of pain and the time from the appearance of symptoms to blood extraction. RESULTS: Thirty-three of the 37 initially included patients were studied. Coronary artery disease was diagnosed in 22, 15 of whom had increased troponin I values, yielding a sensitivity of 68% (48%-84%) and a specificity of 82% (53%-97%). In the subgroup of patients with pain lasting > 30 min, sensitivity reached 85% (59%-97%) and specificity 83% (42%-99%). There were no significant differences between subgroups with different time delays from appearance of symptoms to blood extraction. CONCLUSIONS: Cardiac troponin I is very useful for the studying ischemic chest pain without a definitive diagnostic ECG nor biochemical data, resulting in a high sensitivity and specificity for myocardial ischemic injury detection. Its diagnostic value increases in cases of prolonged pain episodes.

[Identification of the ischemic origin of dilated myocardiopathy using positron emission tomography]. / Identificación del origen isquémico de la miocardiopatía dilatada mediante tomografía por emisión de positrones.

INTRODUCTION AND OBJECTIVES: The aim of this study was to differentiate ischemic from nonischemic dilated cardiomyopathy with positron emission tomography. This differentiation is necessary to establish an adequate treatment, and it is often difficult with non-invasive diagnostic procedures. METHODS: Ten patients with an echocardiographic diagnosis of dilated cardiomyopathy who had undergone coronary angiography were selected. The presence or absence of angiographic coronary lesions was used to define the ischemic (n = 6) and the nonischemic group (n = 4). The ejection fraction was depressed in both groups, with no significant differences found. A perfusion study with 13N-ammonium and a metabolic imaging with 18F-florodeoxyglucose were performed on each patient. The images were quantitatively and qualitatively analysed, defining three criteria: accumulation defect (areas with activity under 50% of the maximal radioactivity), degree of heterogeneity, and match of images with both tracers. To determinate the degree of heterogeneity, nine segments on the three standard tomographic planes were studied. Based on the following heterogeneity features: irregular borders, coexisting different degrees of accumulation, and patched accumulation, a score ranging from 0 to 3 points was assigned to these segments. To analyse the radioactivity defects and the matching of studies with both tracers, the accumulation defects or the accumulating surface were outlined on a midventricular level coronal plane. RESULTS: The ischemic group has contrary to the nonischemic one, wider perfusion (0.26 +/- 0.21 vs 0.00) and metabolism defects (0.38 +/- 0.30 vs 0.06 +/- 0.09; p < 0.05). The degree of heterogeneity is significantly higher in the nonischemic group, either in perfusion (14.5 +/- 8.38 vs 2.5 +/- 1.04; p < 0.05) or in metabolism studies (15.5 +/- 3.31 vs 2.33 +/- 1.50; p < 0.005). Assigning wide defects and homogeneous accumulation to ischemic cardiomyopathy, and absence of defects and heterogeneous accumulation to nonischemic cardiomyopathy, the aetiology of the disease was identified in 9 of the 10 cases in the perfusion study and 100% of them with the metabolism imaging. CONCLUSIONS: Positron emission tomography allows to identify the aetiology of dilated cardiomyopathy, either with coronary perfusion or with myocardial glucose metabolism studies. Thus, only one of both PET studies could be used. Ischemic cardiomyopathy is characterised by wide defects and homogeneous radioactivity, and the nonischemic one by the absence of defects and heterogeneous accumulation of the tracer.

[The use of the average activity contained in the circular areas of interest on the polar map in identifying affected coronary arteries]. / Aplicación de la actividad media contenida en regiones de interés circulares del mapa polar en la identificación de arterias coronarias lesionadas.

INTRODUCTION AND OBJECTIVES: We studied the feasibility to identify coronary lesions of the average regional activity obtained by regions of interest displayed on the three main coronary territories from the polar map (left anterior descending artery, circumflex and right coronary artery). METHODS: In 125 patients with angiographic diagnosis of coronary artery disease, were made tomographic studies with technetium-99m isonitrile to analyze the average regional activity, in rest and stress. RESULTS: According to the stepwise logistic regression test, the stress average regional activity is significant and independent correlated with the stenosis rate (r = -0.60, -0.67 and -0.67 for left anterior descending artery, right coronary artery and circumflex). The thresholds values of the stress average regional activity (percentage of peak activity) with the best assessment of the significant lesions (> 70%) are: less than 70% for left anterior descending artery and circumflex, and less than 60% for the right coronary artery. Using those diagnostic criteria, this quantitative method has a high diagnostic accuracy: Sensitivity/specificity to identify significant lesion of: 0.86/0.93 for left anterior descending artery, 0.85/0.83 for right coronary artery and 0.80/0.90 for circumflex. Significant coincidence with the angiographic diagnosis of the number of diseased vessels (Kappa coefficient 9.62). CONCLUSION: The assessment of the stress average regional activity by circular regions of interest is an easy method, with a high diagnostic accuracy to identify diseased coronary arteries.