Relationship between Augmentation Index and Wall Thickening Fraction during Hypotension in an Animal Model of Myocardial Ischemia-Reperfusion and Heart Failure.

AIMS: Non-invasive indices to evaluate left ventricular changes during ischemic heart failure are needed to quantify the myocardial impairment and the effectiveness of therapeutic manoeuvres. The aims of this work were to calculate the Wall Thickening Fraction (WTF) and the Augmentation Index (AIx) and to assess the relationship between WTF and AIx using data obtained from an animal model with heart failure followed by a myocardial ischemia stage and a reperfusion stage. METHODS: Nine Corriedale sheep that had been monitored for 10 minutes during a basal stage underwent 5-minute myocardial ischemia, followed by 60-minute reperfusion. Seven of them were subjected to an induced heart failure through an overdose of halothane, two of which were treated with intra-aortic counterpulsation during the reperfusion stage. The remaining two animals were monitored during their ischemia-reperfusion stage. RESULTS: Data obtained in the 5 animals suffering from heart failure followed by myocardial ischemia showed that: a) heart failure induction determined decrease in cardiac output, cardiac index and systolic and diastolic aortic pressure (AoP) with respect to their basal values (p<0.05), b) myocardial ischemia decreased the WTF compared with basal and induced heart failure values (p<0.05), c) during the reperfusion stage accompanied by induced heart failure, WTF increased with respect to values observed during the ischemia induction stage (p<0.05); nevertheless, basal values were not recovered after reperfusion (p<0.05). During this 60-minute stage, systolic and diastolic AoP values were lower (p<0.05) than those at the basal stage. CONCLUSION: AIx and WTF values calculated from synchronically recorded values of aortic pressure and left ventricular wall thickness during the reperfusion stage in all animals (n = 9) showed a negative correlation (p<0.05). Analysed data provided evidence of a negative relationship between a left ventricular index of myocardial function and an arterial index obtained from AoP waves.

Characteristics and Determinants of Pulse Pressure-Age Relationship in Healthy and Non-treated Hypertensive Subjects of Argentinean Population.

BACKGROUND: The relationship between the increases in pulse pressure (PP) and arterial stiffness determined by aging or systemic hypertension has been widely reported. These findings are supported by large-cohort analyzes conducted in well-known populations, such as Framingham Study. However, there is evidence that an age-PP curvilinear relationship may exist in hypertensive subjects. This study aimed to evaluate the age-related change in pulse pressure and arterial stiffness in a population-based study. METHODS: Carotid-femoral Pulse Wave Velocity (cfPWV) were obtained in 2075 subjects. RESULTS: Age-related changes of PP showed a curvilinear relationship (R=0.39, p<0.0001) in normotensive subjects, with a nadir at around 50 years of age. On the other hand, the age-cfPWV relationship showed a linear and positive correlation (R=0.72, p<0.0001). PP also showed a curvilinear relationship with age (R=0.36, p<0.0001) in hypertensive subjects, with a nadir around 50 years of age. The age-cfPWV relationship showed a linear and positive correlation (R=0.55, p<0.0001). Similar results were observed in the adult population (age≥16 years). Multivariate analysis showed that age, sex, cfPWV, and mean arterial pressure are determinants of PP values in the entire population; however, this result was not uniform when different subgroups were analyzed. CONCLUSION: In conclusion, age-related changes in PP showed a curvilinear relationship and no parallelism with the age-cfPWV relationship for both normotensive and hypertensive subjects. The determinants of PP impact it differently depending on age and the pathological condition of the subject.