Alejandra Christen

Arterial wall structure and dynamics in type 2 diabetes mellitus methodological aspects and pathophysiological findings.

Type 2 Diabetes Mellitus (DM), or adult-onset diabetes, is being considered as a new pandemic. Cardiovascular disease is the major cause of morbidity and mortality in type 2 DM, due to arterial structure and functional changes. Assessment of arterial structure and biomechanics, by non-invasive methods and parameters, can be used to detect early alterations related to DM. Three markers of vascular disease may help to a better evaluation of vascular dysfunction in type 2 DM patients: carotid intimamedia thickness (IMTc), arterial stiffness, assessed by pulse wave velocity (PWV), and endothelial function, evaluated through the brachial artery flow-mediated dilation (FMD). Among these parameters, IMTc is considered a marker of structural vessel wall properties, and arterial stiffness reflects functional wall properties. Endothelial function represents the arterial way to actively regulate its diameter (smooth muscle-dependent actions) and its visco-elastic properties (wall elasticity and viscosity). IMTc is increased in patients with type 2 DM and other independent risk factors, such as: age, hyperlipidemia and duration of DM. Subjects with DM have shown increased arterial stiffness. Type 2 DM is associated with reductions in FMD (endothelial dysfunction), which has already been reported to be inversely and strongly related to the extent of hyperglycemia. The underlying patho-physiological mechanisms are complex and remain to be fully elucidated. A complete understanding of the association between arterial alterations and early detection, and type 2 DM, may be critical for the primary prevention of DM-related macro-vascular disease.

Dynamic Aortomyoplasty in Treating End-stage Heart Failure

BACKGROUND Dynamic aortomyoplasty is an alternative to heart transplantation. The goal of our study was to evaluate the benefits of aortic counterpulsation obtained using dynamic aortomyoplasty in patients with heart failure refractory to pharmacologic treatment and with contraindications to heart transplant. METHODS In this study, we compared the pre-operative and post-operative data of 15 selected patients who underwent dynamic thoracic aortomyoplasty. In this surgical technique, the right latissimus dorsi muscle flap is wrapped around the ascending aorta. This muscle flap was electrically stimulated during diastole, following a muscle-conditioning protocol, to obtain diastolic augmentation. At 12-month follow-up, we evaluated invasively and non-invasively the hemodynamic, clinical, and functional effects of aortomyoplasty. RESULTS When comparing pre-operative data with 12-month follow-up data, we observed a significant decrease in the number of hospitalizations (p < 0.001) and in the New York Heart Association functional class (p < 0.001), and we observed significant improvement in the walking test (p < 0.001) and in peak oxygen consumption (p < 0.05). CONCLUSIONS Dynamic, biologic, chronic counterpulsation of the aorta using a latissimus dorsi flap (dynamic aortomyoplasty) in selected patients with severe heart failure significantly improved hemodynamic parameters, heart functional data, and clinical functional class. A larger clinical experience with a longer follow-up would be useful in evaluating this techniques clinical relevance.

Dynamic abdominal and thoracic aortomyoplasty in heart failure: assessment of counterpulsation.

BACKGROUND Aortic counterpulsation, either biologic or mechanical, is a useful technique to support circulation during left ventricular dysfunction. METHODS In this study we used an induced cardiac failure model in acute open chest sheep to compare hemodynamic improvements between thoracic and abdominal aortic counterpulsation. This was achieved with left latissimus dorsi and left hemidiaphragm muscle flaps. RESULTS Thoracic and abdominal aortic counterpulsation in heart failure resulted in a significant improvement of hemodynamic parameters. Subendocardial viability index, defined as diastolic pressure-time index to systolic tension-time index, in thoracic and abdominal aortomyoplasty showed significant improvement (p<0.05) when cardiac assistance was performed by electrical stimulation of each muscle flap. A new counterpulsation index derived from diastolic and systolic areas beneath the aortic pressure curve was tested, obtaining a correlation coefficient with the subendocardial viability index of 0.758 (p<0.001). Values of subendocardial viability index and counterpulsation index showed minimal variability. CONCLUSIONS Treatment of experimentally induced cardiac failure with dynamic abdominal aortic counterpulsation allows an effective hemodynamic improvement in open chest sheep. Furthermore, this diastolic arterial pressure augmentation could be evaluated through a new counterpulsation index derived from diastolic and systolic areas beneath the aortic pressure curve.

Benefits of aortic and pulmonary counterpulsation using dynamic latissimus dorsi myoplasty

BACKGROUND Intraaortic and pulmonary artery counterpulsation are useful techniques to support circulation during either left or right ventricular dysfunction. Electrically stimulated skeletal muscles wrapped around the aorta, used as means of cardiac failure treatment, have proved to be an effective method of handling experimental left ventricular failure. In this article we report an induced cardiac failure model in acute open chest dogs and describe the hemodynamic improvement of simultaneous aortic and pulmonary artery counterpulsation. METHODS This was achieved with a bilateral latissimus dorsi muscle flap, stimulated with a software written in C++ for Windows. Dynamic aortomyoplasty was performed using the left latissimus dorsi muscle flap around the descending aorta, and dynamic pulmonaromyoplasty was achieved wrapping the pulmonary trunk with the right latissimus dorsi muscle flap. In all animals blood pressures and cardiac output were measured after cardiac failure induced by a high-dose of propranolol hydrochloride (3 mg/kg intravenously) before and after latissimus dorsi muscle flap stimulation. RESULTS Aortopulmonary counterpulsation resulted in a significant increase in mean aortic pressure, mean pulmonary pressure, and cardiac output. In addition, a significant decrease was observed in end-diastolic left ventricular pressure, systemic vascular resistance, and pulmonary vascular resistance. Subendocardial viability index (diastolic pressure-time index/systolic tension-time index) in aortomyoplasty and tension time index in pulmonaromyoplasty showed significant improvement when cardiac assistance was performed by electrical stimulation of both muscles (p = 0.037 and p = 0.001, respectively). CONCLUSIONS Treatment of experimentally induced cardiac failure using aortopulmonary counterpulsation allows effective hemodynamic improvement in open-chest dogs.

Chronic aortic counterpulsation with latissimus dorsi in heart failure: clinical follow-up.

BACKGROUND Dynamic aortomyoplasty is an alternative technique to heart transplantation. The goal of our study was to evaluate the benefits of aortic counterpulsation obtained by dynamic thoracic aortomyoplasty in patients with heart failure refractory to pharmacologic treatment and contraindications to heart transplant or cardiomyoplasty. METHODS In this study we compared preoperative and postoperative data from five out of six carefully selected patients who were treated with dynamic thoracic aortomyoplasty. This surgical technique wraps the right latissimus dorsi muscle flap around the ascending aorta. This muscle flap was electrically stimulated during diastole, following a muscle-conditioning protocol, to obtain diastolic augmentation. At the 6-month follow-up period we evaluated, invasively and noninvasively, the hemodynamic and clinical effects of aortomyoplasty. RESULTS We observed a significant decrease in the number of hospitalizations (P = 0.01), NYHA functional class (P = 0.01), cardiothoracic ratio (P = 0.02), right ventricular diameter (P = 0.03), left atrial diameter (P = 0.04), and pulmonary artery systolic pressure (P = 0.04); and a significant increase in the 6-minute walking test (P = 0.01), cardiac index (P = 0.04), noninvasive evaluation of diastolic augmentation (P = 0.01), left ventricular shortening fraction (P = 0.01), and radioisotopic left ventricular ejection fraction (P = 0.02). We also found a nonsignificant decrease in the left ventricular diameter (P = 0.08) and wedge pressure (P = 0.19); and a nonsignificant increase in peak oxygen consumption (P = 0.13). CONCLUSIONS Dynamic thoracic aortomyoplasty in heart failure resulted in an important improvement of hemodynamic parameters, heart functional data, and clinical functional class, when comparing preoperative data with the 6-month follow-up data.

Serum Uric Acid Elevation is Associated to Arterial Stiffness in Hypertensive Patients with Metabolic Disturbances

INTRODUCTION Chronic serum uric acid elevation (SUA) is known to be induced by dyslipidemia, hypertension, inflammation, and insulin resistance. Therefore, it has been associated with higher risk for coronary artery disease and cardiovascular mortality. Also, increased levels of SUA have been associated with regional arterial stiffness, assessed by pulse wave velocity (PWV). AIMS To evaluate the relationships of PWV, SUA and different metabolic parameters in essential hypertensive patients. MATERIAL AND METHODS We evaluated 445 essential hypertensive patients, by measuring office blood pressure (BP), weight, height, and waist circumference. In each patient, blood samples were drawn for biochemical evaluations and 24h urine collection. Body Mass Index (BMI) and Glomerular Filtration Rate (GFR) were calculated. Carotid-Femoral PWV and Left Ventricular Mass Index (LVMI) were measured in all patients. RESULTS All subjects (n=402), 242 males (55±0.9 yrs.; BMI: 28.9±0.3 Kg/m2) and 160 females (58±1 yrs.; BMI: 28.1±0.4 Kg/m2) had normal renal function. PWV values showed a significant association with SUA (p<0.001), Systolic BP (p<0.025) and LVMI (p<0.05). SUA showed a significant association, p<0.025: with BMI, Waist Circumference, and HDL-C; p<0.05: with Glycaemia at 120 min, Insulin at 120 min, TG, and LVMI; and p<0.001: with serum Creatinine. Backward Stepwise Regression showed that PWV could be predicted from SUA (p<0.001) and Systolic BP (p<0.05). BMI, Waist Circumference, DBP and HR did not significantly add to the ability of the equation to predict PWV. CONCLUSIONS In this population of essential hypertensive patients, SUA was associated to increased arterial stiffness and to components of the Metabolic Syndrome. These results raise the possibility that a new approach to the role of SUA, linked to cardiovascular stratification, and a most appropriate treatment might be considered.