This study determined whether a pre-operative cardiac “pre-habilitation” (Prehab) program improves the health of elective coronary artery bypass graft (CABG) surgery patients to a greater extent than standard care (StanC). Seventeen elective CABG patients were randomized to StanC (n= 9) or Prehab (n= 8) at Baseline and were followed at 1-2 weeks pre-operatively (Preop) and Three months post-operatively. Functional walking ability was assessed using the 6-Minute Walk Test (6MWT) and 5-meter Gait Speed Test. Baseline data was not different between groups. Patients in StanC did not improve 6MWT scores; whereas Prehab patients improved 6MWT distance by 35% and 39% at Preop and Three months post-operatively, respectively (p<0.05). Gait speed scores were 25% and 27% lower in Prehab patients at Preop and Three months post-operatively, respectively, as compared to StanC (p<0.05). These data suggest that Prehab is an attractive intervention for enhancing functional walking ability before and after elective CABG surgery.

This study determined whether a pre-operative cardiac “pre-habilitation” (Prehab) program improves the health of elective coronary artery bypass graft (CABG) surgery patients to a greater extent than standard care (StanC). Seventeen elective CABG patients were randomized to StanC (n= 9) or Prehab (n= 8) at Baseline and were followed at 1-2 weeks pre-operatively (Preop) and Three months post-operatively. Functional walking ability was assessed using the 6-Minute Walk Test (6MWT) and 5-meter Gait Speed Test. Baseline data was not different between groups. Patients in StanC did not improve 6MWT scores; whereas Prehab patients improved 6MWT distance by 35% and 39% at Preop and Three months post-operatively, respectively (p<0.05). Gait speed scores were 25% and 27% lower in Prehab patients at Preop and Three months post-operatively, respectively, as compared to StanC (p<0.05). These data suggest that Prehab is an attractive intervention for enhancing functional walking ability before and after elective CABG surgery.

Until recently, tests of vascular structure, function and compliance have been used predominantly for assessing the efficacy of treatment – for example, aggressive medical therapy may yield improvements in vascular structure and function with a concomitant decrease in cardiac events. However, the role of abnormal vessel function in the development of atherosclerosis, and the relationship of structural changes in peripheral vessels with coronary disease might suggest that these tests could be used as a screening test for patients with subclinical coronary disease. At present, there is insufficient evidence to support the theory that normal vascular structure and function can rule out significant coronary disease, and indeed, such an association may be confounded by the presence of risk factors that alter these test results in the absence of significant coronary artery disease (CAD). The overall hypothesis of the studies undertaken in this thesis was that utilizing contemporary technology during ultrasonic and tonometric assessment of arterial structure, function and compliance, it is possible to non-invasively characterise both early and advanced arterial dysfunction and identify patients both at risk and with cardiovascular disease. The aim of these studies was to determine whether these tests can be used to guide intervention when arterial dysfunction is diagnosed and whether they are robust enough as a follow-up tool. The thesis initially reviews arterial structure, function and compliance and their relationship to cardiovascular risk and in particular, CAD. This review provides a rationale for the studies undertaken here to resolve clinical and technical issues as well as provide an insight into the tests chosen to assess arterial function. The second chapter discusses the methodology used in these studies to assess arterial structure, function and compliance, diagnose coronary artery disease and determine cardiovascular risk. They range from stress echocardiography for the diagnosis of CAD to tests for arterial structure (carotid intima-media thickness [IMT]), endothelial function (brachial artery reactivity [BAR]), local arterial distensibility (distensibility coefficient [DC]) and systemic or total arterial compliance (TAC). In addition, several methods will be discussed for assessing local arterial elasticity with a novel imaging technique. The rationale for using tests for arterial structure, function and compliance in patients with CAD as well as cardiovascular risk is examined in chapter 3. Chapter 3 examines the use of TAC, IMT and BAR in patients undergoing dobutamine stress echocardiography (DSE) in a group of patients with and without disease. TAC was neither an independent predictor of CAD risk or patients having CAD in this study. BAR was a predictor of risk status but not of patients having CAD. Only IMT was an independent predictor of both patients at risk for CAD and those with CAD. In chapter 3 both pulse pressure and total arterial compliance were only univariate predictors of risk for CAD. Chapter 4 examines three different methods of estimating TAC, all based on the two-element Windkessel model in 320 patients with and without cardiovascular risk. The pulse-pressure method (PPM) is based on a combination of pressure, obtained using applanation tonometry of the radial artery, and an estimate of stroke volume obtained by Doppler echocardiography of the left ventricular outflow and by 2D echocardiographic dimension of the left ventricular outflow tract. The area method (AM) is an integral variation of the Windkessel equations and is based on the derived central pressure waveform. The stroke volume-pulse pressure method (SVPP) is a simple ratio of stoke volume and pulse pressure. We conclude that they correlate well and show similar differences between groups with and without risk. The PPM had the smallest difference from the mean and standard deviation in Bland Altman analysis and we therefore used the PPM for most future studies. Chapter 5 discusses the use of tissue Doppler for the derivation of central pressure and determination of distensibility coefficient, a marker of local arterial elasticity. Tissue Doppler can be used to evaluate the low frequency, high amplitude signals which come from tissue by changing filtering settings on an ultrasound machine. Using off-line software, the tissue velocities can be extracted and with a processing algorithm, vessel wall displacement values over time can be generated. These vessel wall displacement values which are in microns (µm) can then be used to calculated distensibility coefficient which is calculated as 2*((net displacement/minD)/PP). We studied a large group of patients with and without cardiovascular risk and conclude that DC using tissue Doppler correlates highly with DC by B-mode and M-mode imaging and is also very reproducible. In a subgroup, the vessel displacement values were “calibrated” using mean and diastolic pressure and with specialised software and a transfer function, central pressure wave forms were reconstructed. In this study we conclude that the central pressure obtained using tissue Doppler displacement of the carotid artery correlates highly with that obtained using applanation tonometry although there are technical challenges involved. With the known prognostic value of pulse pressure, chapter 6 explores whether there is added benefit to measuring total arterial compliance over pulse pressure alone. Once again patients with and without disease were studied and we conclude that brachial pulse pressure correlates well with TAC in men with normal cardiac function. However, in women and in patients at the low and high extremes of function, and in patients with preclinical and overt cardiovascular disease, there appears to be incremental value in measuring TAC. The role of cardiovascular risk factors in association with TAC is examined in chapter 7. Several studies have shown that TAC is lower in certain groups due to age, height, hypertension, hyperlipidaemia or other factors. We studied 720 patients with and without cardiovascular risk factors and did several multiple linear regression models based on anthropomorphic variables. Age was an independent correlate of TAC in most of the regression models and we conclude that TAC is associated with multiple risk factors, but age is a major determinant. The influence of age and other correlates may dwarf the contribution of individual risk factors and therefore their alteration with therapy. Chapter 8 examines the correlates of preclinical cardiovascular disease in both indigenous and non-indigenous Australians with and without diabetes mellitus (DM). DM is a major health problem in the Indigenous population in Australia and CVD occurs earlier in this group than in caucasians and is responsible for 1/3 of all deaths. We studied a large group of indigenous Australians with and without DM and matched them to a caucasian population. There were no differences in BAR between the groups probably due to large standard deviations in the measurements. In assessing DC, both DM groups had significantly lower DC than the non-DM groups. However, in the IMT analysis both of the indigenous groups had significantly higher IMT than their caucasian counterparts and even after IMT was corrected for age, Indigenous patients even at an early age had significantly higher IMT. We conclude that despite a high incidence of risk factors in indigenous Australians both with and without DM, ethnicity (and various other risk factors for which it is a marker) appears to be an independent predictor of preclinical cardiovascular disease. In chapter 3 we determined that TAC was not an independent correlate of patients either at risk of CAD or with CAD. Chapter 9 discusses the results of a study of patients presenting for stress echocardiography for either detection of CAD or risk stratification. Ischaemia was detected in 25% of cases and TAC was similar in those with and without ischaemia. In multiple linear regression models however, in addition to cardiovascular risk factors TAC was independently associated with both the presence of CAD and the extent of ischaemia at stress echocardiography. Several studies have used vascular function as an outcome measure in intervention trials, either lifestyle or pharmacologic. In chapter 10 we undertook a lifestyle and diet intervention study in a large group of healthy patients with type-II DM. The tests for IMT, BAR and TAC were used in addition to biochemical markers and fitness assessment. At follow-up the intervention group had significant changes in weight and BMI and significantly increased fitness but failed to show any changes in any of the vascular parameters. We conclude that while metabolic and fitness parameters respond to treatment in patients with type-II DM, the early changes seen in vascular structure, function and compliance may not change in the long term. Although TAC has been correlated with hypertension, LVH, myocardial ischaemia and heart failure there are few data existing regarding the relationship of TAC to outcome. In the final chapter of this thesis we sought whether TAC was predictive of outcome in a large, primary prevention group of patients with varying degrees of cardiovascular risk. We followed up 719 patients who were studied between 2001 and 2008 in Brisbane, Australia and examined TAC in relation to mortality and a composite endpoint of death or hospital admission. There were significant differences in groups having low and normal TAC for both death and the composite endpoint and in patients with intermediate and high Framingham 10-year risk TAC was an independent predictor of both death and the composite endpoint. We conclude that TAC correlates with outcome in patients with varying degrees of cardiovascular risk and also adds incremental benefit to Framingham risk alone in patients with intermediate risk.

Thesis (D.P.H.)--University of Michigan.

Thesis (D.P.H.)--University of Michigan.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2003. / Restricted until October 2004. Bibliography: leaves 95-101.

Ischemic heart disease is currently the leading cause of death globally. Coronary artery bypass grafting (CABG) is considered the best treatment for many patients and its success depends on the long-term patency of the conduits. Greater use of arterial grafts has been advocated because of their higher long-term patency compared to saphenous vein grafts (SVGs). Despite this, SVGs account for up to 80% of all grafts used in CABG. Consequently, the long-term patency of the saphenous vein (SV) is one of the most crucial challenges in cardiovascular surgery. The no-touch (NT) SV in CABG has shown a superior patency rate, slower progression of atherosclerosis, and better clinical outcome compared to conventional veins up to 8.5 years postoperatively. The aim of this thesis was to study the long-term angiographic, echocardiographic, and clinical aspects of CABG patients receiving either NT or conventional vein grafts and to investigate the health-related quality of life (HRQoL) in this patient group. Studies I-II report a randomized trial between NT and conventional veins where 74 patients were followed-up at a mean of 16 years postoperatively. Study III is a prospective cohort trial in which 97 patients with NT vein grafts anastomosed to the left anterior descending artery (LAD) were included and followed-up at a mean of 6 years postoperatively. Study IV included 257 patients in whom HRQoL and graft patency were studied during the same follow-up visit. Overall, NT vein grafts showed a higher patency compared to conventional veins at a mean of 16 years, 83% vs. 64% (p=0.03), which was similar to the patency of the left internal thoracic artery, 88%. The NT group had a better left ventricular ejection fraction compared to the conventional group, 57.9% vs. 49.4% (p=0.011). After a mean of 6 years, the patency rate of NT SVs to the LAD was 95.6% and to non-LAD targets, 93.9%. Graft patency was an independent predictor of HRQoL in CABG patients. These patients reported a function and wellbeing similar to that of the Swedish population and clearly higher health status than those in the same disease group in the general population.

Abstract The identification of risk factors for major adverse events after coronary artery bypass surgery is of main importance as it allows outcome prediction, facilitates preoperative patient selection and improves the quality of care. In the present clinical studies we have evaluated the impact of preoperative angiographic severity of a coronary artery disease and preoperative C-reactive protein (CRP) on the immediate outcome after coronary artery bypass surgery. We have reviewed the results of off-pump (OPCAB) versus conventional on-pump coronary artery bypass surgery (CCAB) in high risk patients. We have evaluated the impact of postoperative pulmonary artery blood temperature on the immediate outcome as well. In addition, we have investigated the incidence, timing and outcome of an atrial fibrillation (AF) related stroke after surgery. The multivariate analysis showed that among 2233 patients, the overall coronary angiographic score was predictive of postoperative death (p = 0.03; OR 1.027, 95% CI: 1.003–1.052) and of a low cardiac output syndrome (p = 0.04; OR 1.172, 95% CI: 1.010–1.218). The poor status of the proximal segment of the left circumflex coronary artery, the diagonal branches and the left obtuse marginal artery were most closely associated with adverse postoperative outcome. Patients (114/764) with a preoperative serum concentration of CRP ≥ 1.0 mg/dL had a higher risk of overall postoperative death (5.3% vs. 1.1%, p = 0.001), cardiac death (4.4% vs. 0.8%, p = 0.002), a low cardiac output syndrome (8.8% vs. 3.7%, p = 0.01). Among 179 high risk patients with an additive EuroSCORE6, the 30-day postoperative death and stroke rates were 7.5% and 6.0% in the OPCAB group, and 5.4% (p = 0.75) and 8.0% (p = 0.77) in the CCAB group, respectively. No significant differences were observed in other major outcome end-points between these non-randomised groups either. High pulmonary artery blood temperature on admission to the ICU among 1639 patients was significantly associated with an increased risk of overall postoperative death (p = 0.002), cardiac death (p = 0.03), and a low cardiac output syndrome (p &lt; 0.0001), and was significantly correlated with prolonged length of the ICU stay (r = 0.095; p &lt; 0.0001), and postoperative bleeding (ρ = –0.091; p = 0.001). Among 2,630 patients who underwent coronary artery bypass grafting (CABG), 52 (2.0%) experienced a postoperative stroke. Twelve out of these 52 patients (23.1%) died postoperatively. The ischemic cerebral event occurred after a mean of 3.7 days (0–33). In 19 patients (36.5%), atrial fibrillation preceded the occurrence of neurological complication. The angiographic severity of the coronary artery disease and the preoperative serum concentration of CRP predict postoperative outcome after a CABG operation. OPCAB can be performed safely in high-risk patients with results as satisfactory as those achieved with CCAB. CABG patients with a high pulmonary artery blood temperature on admission to the ICU seem to have a higher risk of postoperative adverse events. Atrial fibrillation occurring after coronary artery bypass grafting is a major determinant of a postoperative stroke.

Orientador: Wilson Nadruz Junior / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-22T09:54:44Z (GMT). No. of bitstreams: 1 Gemignani_Tiago_D.pdf: 3089084 bytes, checksum: aedee263d43b0d61197caea8058ed566 (MD5) Previous issue date: 2013 / Resumo: As artérias dos membros inferiores são submetidas a uma maior sobrecarga hemodinâmica na posição ortostática. Este estudo avaliou os efeitos da variação postural sobre a tensão circunferencial na parede das artérias poplíteas, carótidas e braquiais, bem como investigou a correlação entre a tensão circunferencial e a presença de placas ateroscleróticas nestas artérias em uma população com fatores de risco cardiovascular. Duzentos e três indivíduos (118 mulheres e 85 homens) com fatores de risco cardiovascular (tabagismo, hipertensão arterial e diabetes mellitus) foram estudados clínica e laboratorialmente, sendo a pressão arterial mensurada nos braços e panturrilhas, tanto em posição supina como ortostática. As artérias foram avaliadas por ultrassonografia, enquanto a tensão circunferencial foi calculada de acordo com a Lei de Laplace. Nos indivíduos participantes, observou-se a presença de placas ateroscleróticas em 47%, 29% e 0% das artérias poplíteas, carótidas e braquiais, respectivamente. As medidas de tensão circunferencial em artérias carótidas não foram associadas à presença de placas ateroscleróticas após ajuste pelas variáveis confundidoras. Por outro lado, as análises de regressão logística e de modelo linear geral mostraram, após ajuste pelas variáveis confundidoras, que a tensão circunferencial sistólica ortostática foi o único parâmetro hemodinâmico local que demonstrou correlação significativa com placas ateroscleróticas poplíteas em toda amostra estudada. Na análise específica por sexos, apesar da correlação positiva com a presença de placas ateroscleróticas poplíteas em ambos os sexos, a tensão circunferencial sistólica ortostática exibiu associação independente com placas ateroscleróticas somente em mulheres, após ajuste pelas variáveis confundidoras. Em conclusão, a tensão circunferencial ortostática poplítea e não a em posição supina, é associada com placas ateroscleróticas em artérias poplíteas, particularmente em mulheres. Estes dados sugerem que a posição ortostática pode desempenhar uma função importante na aterogênese das artérias dos membros inferiores, modificando as forças hemodinâmicas locais, podendo, contudo, haver diferença entre os sexos / Abstract: Lower limb arteries are exposed to higher hemodynamic burden in erectile posture. This study evaluated the effects of body posture on popliteal, carotid and brachial circumferential wall tension (CWT) and investigated the relationship between local CWT and atherosclerotic plaques in subjects with cardiovascular risk factors. Two hundred and three subjects (118 women and 85 men) with cardiovascular risk factors (smoking, hypertension or diabetes mellitus) underwent clinical and laboratory analysis and had their blood pressure measured in the arm and calf in supine and orthostatic positions. Arteries were evaluated by ultrasound analysis, while CWT was calculated according to Laplace's law. Among the enrolled participants, 47%, 29% and none presented popliteal, carotid and brachial plaques, respectively. Carotid CWT measurements were not associated with local plaques after adjustment for potential confounders. Conversely, general linear model and logistic regression analyses adjusted for potential confounders demonstrated that peak orthostatic CWT was the only local hemodynamic parameter showing significant relationship with popliteal plaques in the whole sample. In gender-specific analyses, although positively correlated with popliteal plaques in both genders, local peak orthostatic CWT exhibited an independent association with popliteal plaques after adjustment for potential confounders only in women. In conclusion, popliteal CWT measured in orthostatic posture, rather than in supine position, is associated with popliteal atherosclerotic plaques, particularly in women. These findings suggest that orthostatic posture might play a role in the atherogenesis of leg arteries by modifying local hemodynamic forces and that there may be gender differences in this regard / Doutorado / Clinica Medica / Doutor em Clínica Médica

The thesis focuses on the measurement of intima media thickness, which seems to be a significant marker of the risk of cardiovascular events. Intima media thickness is measured in ultrasound image displaying the common carotid artery in its longitudinal section. In the longitudinal section the intima and media layers are visible. Thesis is discussing both technical and medical background and summarizes state of the art in this field. The main part of the thesis describes the novel automatic system for measurement of intima media thickness. Proposed system includes also robust method for artery localization and therefore is able to process raw B-mode data from ultrasound station without any initialization or manual preprocessing.