EVALUATION OF CARDIOVASCULAR FUNCTIONAL RESPONSE TO ORTHOSTATISM IN TREATED HYPERTENSIVE PATIENTS: RESULTS OF THE IMPEDDANS STUDY

Abstract

Objective: Arterial Hypertension (AHT) is one of the main causes of morbidity and mortality in the world. Generally defined as an increase in blood pressure (BP), it is characterized by hemodynamic changes that have implications for diagnosis, risk stratification and therapy. In this study we intend to characterize the hemodynamic response to orthostatism in a group of treated hypertensive patients using impedance cardiography (ICG). Design and method: Resistant hypertensive patients without heart failure, ischemic heart disease, valvular heart disease or dysrhythmia were prospectively selected. All patients underwent ICG in the supine position and in orthostatism. After ICG, they were classified into patterns: vasoconstrictor (systemic vascular resistance (SVR) > 2500 dyn.s.cm-5.m2), hyperdynamic (cardiac index (CI) > 4.2 l / min / m2 and / or heart rate HR > 80 cycles / min), hypervolemic (thoracic fluid (CFT) > 34 1 / kOhm) or balanced (hemodynamic parameters below the established limit values). All patients underwent transthoracic echocardiography to exclude major morphologic changes. Results: We included 178 patients, 56.1% males, age 63 ± 11 years, medicated with 4 ± 1 antihypertensives. In ICG, 56.5% were vasoconstrictors, 11.8% hyperdynamic, 33.4% hypervolemic and 22.9% had a balanced hemodynamic profile. In the supine position the patients had systolic blood pressure 134 ± 18, diastolic blood pressure 79 ± 11, HR 69 ± 10, indexed ejection volume 42 ± 9, pre-ejection period 95 ± 15 ms, ejection time 333 ± 17 ms, systolic time ratio 0.28 ± 0.06, RVSI 2687 ± 621, cardiac index 2.8 ± 0.4 and CFT 32 ± 5. In the orthostatic position some of these values were significantly higher: diastolic blood pressure 82 ± 12 (p < 0.001), HR 73 ± 12 (p < 0.001), pre-ejection period 119 ± 23 (p < 0.001), systolic time ratio 0.41 ± 0.11 (p < 0.001). The indexed ejection volume 39 ± 9 (p < 0.001), ejection time 301 ± 46 (p < 0.001) and CFT 28 ± 3 (p < 0.001) were significantly lower. Conclusions: Although polymedicated, most patients had an unbalanced hemodynamic profile. The analysis of the impedance waveform with postural modification can be used to clarify the response to orthostatism and to better characterise the hemodynamic phenotype.