Assessment of the left ventricular diastolic reserve in essential hypertension: the acute saline load test

OBJECTIVE: The aim of this study was to evaluate the significance of the development of a restrictive response to an acute saline load, defined as an increase in the ratio of peak early to peak late diastolic transmitral flow velocity (E/A ratio) associated with a decrease in the deceleration time, in patients with mild to moderate untreated hypertension. BACKGROUND: Recognised abnormal patterns of transmitral diastolic flow include, from 'best' to 'worst': prolonged relaxation, pseudonormalisation, and restrictive physiology. The common denominator of these transitions is the constellation of an increase in the E/A ratio associated with a decrease in deceleration time. PATIENTS AND METHODS: Sixteen normal control subjects (6 males, 10 females, age 51.6 +/- 6.9 years) and 24 patients with mild to moderate untreated hypertension (12 males, 12 females, age 46.8 +/- 7.5 years) underwent supine blood pressure measurement with sphygmomanometry, biochemical studies, and transthoracic M-mode, 2D, and Doppler echocardiography before and after an acute saline load (7 mL kg(-1), maximum 500 mL, NaCl 0.9% within 15 min IV). RESULTS: The baseline E/A ratio was lower (0.90 +/- 0.14 vs. 1.04 +/- 0.18; P < 0.01) and the deceleration time was longer (158.8 +/- 19.4 vs. 135 +/- 8.9 ms; P < 0.01) in patients with hypertension compared with normotensive controls. However, no patient with hypertension exhibited a transmitral flow velocity pattern compatible with typical prolonged relaxation. A restrictive response to the acute saline load was observed in 12 (50%) of the hypertensive and none of the control subjects. Hypertensive patients with a restrictive response to the acute saline load had a lower baseline E velocity (54.8 +/- 8.7 cm s(-1) vs. 66 +/- 6.4 cm s(-1); P = 0.003), a lower baseline E/A ratio (0.83 +/- 0.13 vs. 0.97 +/- 0.12; P = 0.015), and a longer deceleration time (167.5 +/- 15.4 ms vs. 150 +/- 19.5; P = 0.03) than hypertensive patients without such a response. CONCLUSION: A restrictive response to an acute saline load is indicative of a limited diastolic reserve in patients with mild to moderate untreated hypertension. Further studies are required in order to evaluate the significance of such a response with regards to risk stratification and efficacy of medical treatment in this patient population.