[Usefulness of the Doppler index delta P/delta t in the evaluation of left ventricular systolic dysfunction]. / Utilidad del índice Doppler delta P/delta t en la evaluación de la disfunción sistólica ventricular izquierda.

INTRODUCTION AND OBJECTIVES: It has been shown that the delta P/delta t index, derived from the continuous Doppler mitral regurgitation signal correlates strongly with dP/dt. This study evaluates the feasibility, reproducibility and correlation of the index with ejection fraction and other conventional echocardiographic parameters. MATERIAL AND METHODS: One hundred and ten patients with mitral regurgitation demonstrated by colour Doppler were studied. delta P/delta t were calculated by the ratio between the interval of pression between two points of the Doppler signal (-1 and -3 m/s; 32 mmHg, applying the modified Bernouilli equation) and the interval of time (s) which separates both. Ejection fraction was measured in 70 patients by non-echocardiographic methods (isotopic ventriculography, n = 52, and angiography, n = 18). RESULTS: The index was feasible in 91 cases, the variability of intra and interobserver was 5% and 7% respectively. The correlation between delta P/delta t and ejection fraction was significant although weak (r = 0.59; p < 0.001; n = 70). It was better in the group of dilated idiopathic myocardiopathy (r = 0.72; p < 0.001; n = 18) than in the group of myocardial infarction (r = 0.54; p < 0.01; n = 25). No significant correlation was founded in the cases with mitral rheumatic valvulopathy. Regarding to the echocardiographic parameters, the best correlation was obtained with end systolic diameter (r = -0.64; p < 0.001; n = 49). Finally, a value of delta P/delta t < 1,000 mmHg/s predicted the existence of left ventricular systolic dysfunction with high accuracy (84%), sensitivity (80%) and specificity (92%). CONCLUSIONS: High feasibility when mitral regurgitation exists, adequate reproducibility and heightened precision in diagnosing left ventricular systolic dysfunction, are characteristics which make delta P/delta t useful in the echocardiographic routine practice.

[Syncope and chest pain. Demonstration of the mechanism by the hyperventilation test]. / Síncope y dolor torácico. Demostración del mecanismo mediante test de hiperventilación.

Two patients admitted to hospital because syncope and chest pain are presented. In both patients, hyperventilation test caused severe myocardial ischaemia (ST segment elevation) and sudden development of presyncopal sustained ventricular tachycardia which immediately responded to intravenous nitroglycerin. The relationship between coronary vasospasm and sudden death secondary to polymorphic ventricular tachycardia is discussed. Also, the usefulness of the hyperventilation test to detect this problem and to monitor its therapeutic response is addressed.