P24 Restored Physiological Local Carotid Pulse Wave Velocity After Bariatric Surgery in Obese Subjects

AbstractObesity is a risk factor for cardiovascular events and is associated with increased arterial stiffness [1,2]. However, the effect of drastic changes in Body Mass Index (BMI) on arterial mechanics has not been fully investigated. Our study aimed at evaluating changes in local carotid PWV (cPWV) in obese patients before and 6 months after bariatric surgery. N = 20 obese subjects free of cardiovascular events and diabetes (44 ± 9 years, 5 men, BMI = 48.8 ± 7.5 kg/m2) undergoing bariatric surgery were recruited in the Pisa University Hospital (Italy). Flow and diameter waveforms were acquired by ultrasound scanner (Aloka Alpha10, Hitachi Group, Japan) (1 kHz) at the right common carotid artery at baseline, after a 32.4 ± 7.6 days diet period, and 6.5 ± 2.7 months post-intervention. The lnDU-loop method was used for the estimation of cPWV [3]. Basal cPWV was 6.05 ± 1.21 m/s. The 1-month diet period produced a 2 kg/m2 reduction in BMI, while cPWV decreased by approx. 0.6 m/s. 6–7 months after bariatric surgery, BMI dropped to 35.3 ± 6.5 kg/m2 and cPWV furtherly decreased of approx. 0.9 m/s reaching a mean value of 4.57 ± 1.02 m/s (76% of the basal value) (Figure 1). Bariatric surgery and the consequent intensive weight loss produced a significant decrease of arterial stiffness and restored cPWV to physiological values of age-matched healthy subjects [4]. The fast reversal of increased arterial stiffness suggests a functional mechanism possibly related to a reduced haemodynamic load. Moreover, while having a small effect on the BMI, 1-month diet regulation effectively decreased cPWV by 10%, possibly indicating the short-term positive effects of a healthy lifestyle on haemodynamics

Carotid Reservoir Pressure Decrease After Prolonged Head Down Tilt Bed Rest in Young Healthy Subjects Is Associated With Reduction in Left Ventricular Ejection Time and Diastolic Length

BACKGROUND: The arterial pressure waveform reflects the interaction between the heart and the arterial system and carries potentially relevant information about circulatory status. According to the commonly accepted ‘wave transmission model’, the net BP waveform results from the super-position of discrete forward and backward pressure waves, with the forward wave in systole determined mainly by the left ventricular (LV) ejection function and the backward by the wave reflection from the periphery, the timing and amplitude of which depend on arterial stiffness, the wave propagation speed and the extent of downstream admittance mismatching. However, this approach obscures the ‘Windkessel function’ of the elastic arteries. Recently, a ‘reservoir-excess pressure’ model has been proposed, which interprets the arterial BP waveform as a composite of a volume-related ‘reservoir’ pressure and a wave-related ‘excess’ pressure. METHODS: In this study we applied the reservoir-excess pressure approach to the analysis of carotid arterial pressure waveforms (applanation tonometry) in 10 young healthy volunteers before and after a 5-week head down tilt bed rest which induced a significant reduction in stroke volume (SV), end-diastolic LV volume and LV longitudinal function without significant changes in central blood pressure, cardiac output, total peripheral resistance and aortic stiffness. Forward and backward pressure components were also determined by wave separation analysis. RESULTS: Compared to the baseline state, bed rest induced a significant reduction in LV ejection time (LVET), diastolic time (DT), backward pressure amplitude (bP) and pressure reservoir integral (INTPR). INTPR correlated directly with LVET, DT, time to the peak of backward wave (bT) and stroke volume, while excess pressure integral (INTXSP) correlated directly with central pressure. Furthermore, Δ.INTPR correlated directly with Δ.LVET, and Δ.DT, and in multivariate analysis INTPR was independently related to LVET and DT and INTXSP to central systolic BP. CONCLUSION: This is an hypothesis generating paper which adds support to the idea that the reservoir-wave hypothesis applied to non-invasively obtained carotid pressure waveforms is of potential clinical usefulness

Grandi arterie e accoppiamento ventricolo-arterioso nell'obesità patologica prima e dopo decremento ponderale

L'elaborato si propone, fornita una preliminare analisi dei principi basilari della fisiologia cardiaca, di valutare quelli che sono i modelli teorici più diffusi, e storicamente più importanti, rappresentanti il sistema cardiovascolare, al fine di esaltarne i punti di forza e, nel contempo, evidenziarne i limiti. Quindi, si introdurranno i concetti, relativamente nuovi, di wave intensity analysis e reservoir wave model, al fine di superare le problematiche mostrate dai modelli classici. Infine, ci si focalizzerà sull'applicazione pratica di questi modelli in un protocollo sperimentale concernente l'analisi di soggetti obesi, prima e dopo decremento ponderale, al fine di individuare, i meccanismi fisiopatologici che si celano dietro l'aumento del rischio cardiovascolare in questa popolazione. Aumento del rischio che si rifletterà nell’alterazione di quei parametri che, in accordo con i succitati modelli, predicono il comportamento del sistema cardiovascolare; parametri che poi, si normalizzeranno in ragione della perdita di massa corporea e di tessuto adiposo, come confermato dai test statici condotti, confermandone sensibilità e accuratezza

LOW CAROTID ARTERIAL STIFFNESS IN YOUNG TYPE1 DIABETIC PATIENTS COMPARED WITH AGE-MATCHED CONTROLS

Background: Local pulse wave velocity (c) is widely used as an index of local carotid arterial stiffness. In middle-aged type1 and type2 diabetic patients, arterial stiffness is higher than in healthy people, but much less data are available for young subjects. Our aim was to quantify the changes in c asso- ciated with ageing and type1 diabetes in young patients. Methods: Pressure and diameter waveforms of healthy control (n Z 53, 29 male, mean age 39 ` 17) and type1 diabetic (n Z 20, 15 male, mean age 19 ` 2.5) subjects have been acquired simultaneously using tonometry (500 or 1000Hz) and an ultrasound probe (1kHz) at the level of the left and right common carotid artery, respectively. The geometrical similarity between the right and left common carotid artery was verified, and the two signals were assumed as recorded at the same site. The PD2-loop method [1] was used to calculate c in late diastole as follow: c Z D0dPr d(D2). Results: In controls, c remained approximately constant up to ages 35e44y, at `4 m/s. From 45e54 years old, c increased up to 7m/s in elderly subjects (figure1-left). In young diabetic subjects (15e24), c was lower than in aged- matched control subjects (mean `95% C.I., diabetic 3.51 ` 0.007 and con- trol 3.78 ` 0.005, p < 0.05) (figure1-right). Conclusions: Local stiffness increases with age in the human carotid artery. As found for the descending thoracic aorta previously[2], younger T1 diabetic patients may have more compliant vessels initially, aggravating their ten- dency to stiffen later

Weight Loss After Bariatric Surgery Significantly Improves Carotid and Cardiac Function in Apparently Healthy People with Morbid Obesity

PURPOSE: Obesity clearly increases cardiovascular risk, often inducing high blood pressure (BP), impaired left ventricular (LV) function, and increased arterial stiffness. Intensive weight loss and bariatric surgery induce improvement in hypertension and diabetes for morbid obesity. Carotid artery haemodynamics is a powerful prognostic indicator for stroke and cognitive decline independent of BP. The aim of this study was to evaluate the impact of a 3-stage bariatric strategy of diet, bariatric surgery, and consequent weight loss on carotid haemodynamics and cardiac diastolic function. MATERIAL AND METHODS: This prospective study included 26 patients (45 ± 10 years, 4 men) with severe obesity undergoing bariatric surgery without comorbidities (hypertension, diabetes, etc.). Anthropometry, BP, Doppler echocardiography, and common carotid haemodynamics by ultrasound were measured at three times: (1) baseline, (2) after 1-month diet (post-diet), and (3) 8 months after surgery (post-surgery). The lnDU-loop method was used to estimate local carotid pulse wave velocity (ncPWV). RESULTS: Baseline BMI was 47.9 ± 7.1 kg/m2 and reduced by 5% and 30% post-diet and post-surgery, respectively. BP decreased only post-diet, without pulse pressure change. However, ncPWV, 6.27 ± 1.35 m/s at baseline, was significantly reduced by 10% and 23% post-diet and post-surgery, respectively, also adjusted for BP changes. The E/A ratio rose from 0.95 ± 0.20 to 1.27 ± 0.31 (p < 0.005), without change in LV geometry or mass, while heart rate and cardiac output fell substantially. CONCLUSION: Weight loss following diet and bariatric surgery is associated with reduced carotid arterial stiffness and improved LV diastolic function. Diet and bariatric surgery are effective treatments for morbid obesity with its concomitant adverse cardiovascular effects