Haemodialysis patients represent an extreme phenotype of cardiovascular risk with a pattern of disease distinct from that in the general population. Non-traditional risk factors, specific to chronic kidney disease such as hypervolaemia, arterial stiffness and advanced glycation end-product deposition are increasingly recognised. A previously demonstrated non-traditional risk factor associated with worse outcomes is the presence of uraemic cardiomyopathy. This pattern of cardiac morphology and function has previously been defined as the presence of left ventricular abnormalities, including left ventricular hypertrophy, dilatation and left ventricular systolic dysfunction. For the first time the work in this thesis studies an incident haemodialysis population using multi-parametric strain-based imaging. This uses the accuracy of cardiovascular magnetic resonance imaging of resting cardiac and aortic morphology and function augmented with strain by tagging to longitudinal strain changes during haemodialysis by speckle-tracking echocardiography. The general aim of this thesis was to characterise the relationship of left ventricular function to haemodialysis using strain-based imaging. This might allow characterisation of haemodialysis-associated cardiomyopathy which may be distinct from the traditional definition of uraemic cardiomyopathy and may better define those patients who would benefit from modifications to the process of haemodialysis.

Background: Patients awaiting cardiac surgery typically experience physical and psychological stress. Although there is evidence that preoperative education can improve postoperative outcomes among general surgical patients, less is known about preoperative education for patients undergoing cardiac surgery, particularly in the context of healthcare delivered in China. Aim: The aim of this study was to evaluate whether a preoperative education intervention designed for Chinese cardiac patients could reduce anxiety and improve recovery. Methods: A randomised controlled trial was conducted between December 2009 and May 2010 at two public hospitals in Luoyang, China. Adult patients undergoing cardiac surgery were randomly allocated to usual care or preoperative education that included usual care plus an information leaflet and verbal advice. All outcomes were recorded at seven days following surgery. The primary outcome was change in anxiety measured by the Hospital Anxiety and Depression Scale (HADS). Secondary outcomes were change in depression (HADS), change in pain as measured by the Brief Pain Inventory short form (BPI-sf), length of ICU stay and postoperative hospital stay. A qualitative evaluation was carried out with a sample of 20 trial participants (ten from each group) to explore their views on preoperative education and their experiences of taking part in the trial. Results: A total of 153 patients were recruited to the trial, 77 of which were randomly allocated to usual care and 76 to preoperative education. Of these, 135 (88.2%) completed the trial. The participants who received preoperative education experienced a greater decrease in anxiety score (mean difference -3.6 points, 95% CI -4.62 to -2.57; P<0.001) and a greater decrease in depression score (mean difference -2.1 points, 95% CI -3.19 to -0.92; P<0.001) compared with those who did not. There was no difference between groups in average pain, current pain, and interference in general activity, mood and walking ability. Patients in the preoperative education group reported less interference from pain in sleeping (mean difference -0.9 points, 95% CI -1.63 to -0.16; P=0.02). There was borderline evidence to suggest a reduced number of hours spent in the ICU among preoperative education patients (P=0.05) but no difference in length of postoperative hospital stay (P=0.17). Eleven themes were generated from the qualitative interviews. These were collapsed into three categories: the process and context of information giving and trial experience. Most interview participants commented that communication between patients and healthcare providers was limited, reactive and rarely interactive. Those who received the preoperative education intervention reported that they valued both the written and verbal information. Participants welcomed the opportunity to engage with the trial, and made suggestions concerning future preoperative education. Conclusions: This form of preoperative education is effective in reducing anxiety and depression among Chinese cardiac patients. Preoperative education should be incorporated into routine practice to prepare Chinese cardiac patients for surgery. More trials of complex interventions delivered in China are needed to provide evidence for Chinese healthcare. Trial registration: Current controlled trials ISRCTN87451169.

The development of sepsis is associated with complex cardiovascular changes, some of which can be micmked in animals by administration of lipopolysaccharide (LPS). Animal models have identified a number of mediators important in these changes. The work described within this thesis aimed to investigate the role of adrenomedullin (AM) and adenosine in regulating vascular function in vivo in normal and LPS-treated rats. Integrated haemodynamics were assessed in Sprague Dawley rats following implantation of pulsed Doppler flow probes, allowing changes in renal, mesenteric and hindquarters vascular conductance to be measured across time. Adrenomedullin (AM), a hypotensive peptide involved in cardiovascular regulation, is upregulated in sepsis. Intermedin (IMD) is related to AM and shares some of its functions. However, the in vivo integrated responses to IMD have yet to be determined. In normal rats, both peptides caused marked vasodilatations in all regions, with hypotension and tachycardia. IMD was a more potent vasodilator than equimolar AM. Next, mechanisms involved in IMD signalling were investigated and compared to AM. Both AM and IMD-mediated renal and mesenteric vasodilatation were attenuated by AM22-52 and some components of IMD were sensitive to L-NAME, suggesting IMD causes both endothelial-dependent and -independent vasodilatations. No role for KATP channels was found, but there was an enhanced response to AM in the presence ofU37883A ; this was due to inhibition of the renin-angiotensin system as assessed by the angiotensin II receptor antagonist losartan. To assess whether vascular sensitivity to AM and IMD was affected in an LPS model of endotoxaemia, rats were treated with LPS and responses to peptides were assessed at 1.5 h, 6 hand 25 h. Vascular hyporesponsiveness to both AM and IMD occurred at 1.5 h, but had returned by 25 h regardless of the LPS administration protocol. Thus, vascular hyporesponsiveness appears to be a common phenomenon during the early stages of LPS-induced endotoxaemia. The role of adenosine was then examined in the haemodynamic sequelae of sepsis, since evidence suggests that adenosine-mediated vasodilatations help to maintain regional perfusion in animal models. In control rats, endogenous adenosine caused bradycardia and vasodilatation, whereas there was evidence of regional vasoconstriction in LPS-treated rats. In control animals, exogenous adenosine caused hypotension, tachycardia and vasodilatation, but in LPStreated rats, the adenosine-induced renal (at 1.5 h) and hindquarters (at 6 h) vasodilatations were abolished. As enhanced A1 receptor-mediated vasoconstriction could explain the results in LPS-treated rats, responsiveness to an At-receptor agonist (CCPA) or antagonist (DPCPX) was assessed. There was no evidence for enhanced vasoconstrictor responsiveness to CCP A in LPS-treated rats, but DPCPX caused renal vasodilatation, consistent with endogenous adenosine mediating renal vasoconstriction. Finally, the effects of a subdepressor infusion of adenosine on the haemodynamic responses to AM and IMD were assessed, and vice versa, to determine whether any synergism exists between these agents. No synergism was found between adenosine and AM, but there was functional antagonism between adenosine and IMD in the mesenteric vasculature. Collectively, these studies suggest that the development of novel cardiovascular therapies for treatment of sepsis should be designed to take into account the vascular region, and the time elapsed from onset.

In recent years it has become apparent that hydrogen sulphide (H2S) is an important biological mediator. In the vasculature, it produces complex responses: contraction in some blood vessels, relaxation in others, via multiple mechanisms. This thesis examined the relationship between H2S and oxygen in determining vascular responsiveness, and was conducted using porcine splenic and mesenteric arteries. Studies were also conducted using porcine splenic veins, since few studies have examined venous function. Additionally, studies were extended to the resistance vasculature by determining responses to a H2S donor in small arteries isolated from the rat mesentery. Porcine vessels were set up in an isometric tension recording system and rat small mesenteric arteries were set up in a pressure myograph. Vessels were pre-contracted and responses to the H2S donor, NaHS, were generated in the presence and absence of putative inhibitors, under either 95% O2:5% CO2, 95% air:5% CO2 or 95% N2:5% CO2 gassing conditions. Generally, in both porcine arteries and veins, when gassing with higher oxygen levels (95% O2:5% CO2 or 95% Air:5% CO2), NaHS induced contractile responses, whereas gassing with a lower oxygen level (95% N2:5% CO2), NaHS induced vasorelaxation. At higher O2 levels, removal of the endothelium or, the nitric oxide (NO) synthase inhibitor L-NAME, significantly attenuated contractile response in all porcine vessels. This suggests an interaction between endothelium-derived NO and NaHS, whereby the removal of the vasorelaxatory influence of NO resulted in contraction. In porcine arteries, relaxation at lower O2 levels was attenuated by glibenclamide, suggesting that NaHS activated KATP channels to cause relaxation. In porcine veins, removal of the endothelium or, L-NAME, abolished NaHS-induced relaxation, showing this relaxation occurred via the release of endothelium-derived NO. In rat mesenteric small arteries responses to NaHS did not change with different O2 levels and NaHS-induced vasodilatation that was abolished by desensitization of sensory nerves with capsaicin or the presence of BIBN 4096. These observations suggest NaHS-induced vasodilatation is mediated via release of CGRP from sensory nerves. Thus, responses to NaHS in large conduit arteries and veins, are sensitive to the prevailing level of O2 the tissue is exposed to. At more physiological levels of O2 the predominant response is a vasorelaxation, mediated by either, activation of KATP channels in arteries or, the release of NO in veins. In small arteries, the predominant response is a vasodilator response, involving the release of neuropeptides from sensory nerves. The predominance of a vasorelaxant/vasodilator response is consistent with the observation that mice which lack the capacity to generate endogenous H2S are hypertensive.

UK hospital-based Cardiac Rehabilitation (CR) programmes offer eligible Coronary Heart Disease (CHD) patients information on various issues including lifestyle modification and medicines. However, CR patients' perspectives on medicine-taking and lifestyle modification in relation to their perspectives on their risk of experiencing further CHD-related events remains under-researched. This study explored these topics. Following ethical approval, a qualitative approach was taken that drew on the broad principles of grounded theory. In-depth, audiotaped interviews were conducted with sixteen CR patients approximately three months after hospital discharge. Second interviews explored whether heart attack CR patients' perspectives on risk, medicines and lifestyle modification had changed when interviewed again approximately nine months later. The perspectives of a group of CR patients who had not had a heart attack were explored for comparison. Findings suggested that CR patients made sophisticated yet uncertain assessments of their risk. This did not just involve identifying lifestyle factors needing change or attributing the likelihood of experiencing further CHD-related events to chance or heredity alone; patients tended to also consider information about heart damage or current heart function. Heart attack patients commonly feared recurrence, which appeared to heighten short-term perceptions of risk but longer-term perspectives on risk appeared similar to CR patients who had not had a heart attack. CR patients tended to only maintain changes to aspects of lifestyle perceived as causes, rather than viewing lifestyle recommendations as standards to achieve. Some heart attack patients initially changed aspects of lifestyle they did not cite as a cause, which seemed to be associated with heightened risk perceptions, since these changes tended not to be maintained. CR patients reported continuing to take heart-related medicines and viewed them as important to reduce their risk, despite disquiet about medicines causing harm being common. These findings have implications for health professionals' practice and CR programme improvement.

Cardiac development is a complex multi-step process involving a diverse network of genes. Defects in cardiac genes can lead to congenital heart defects (CHDs), and understanding the processes involved in normal cardiogenesis is crucial in elucidating the pathogenesis of disease. Mutations in a number of cardiac transcription factors have been associated with CHDs, including TBX5 and GATA-4. These transcription factors are high in the regulatory hierarchy and form a complex that is thought to direct and synergistically regulate common cardiac pathways. However, little is currently known about their joint targets. This study aimed to identify and analyse genes important in cardiogenesis, with focus on the combined targets of TBX5 and GAT A-4. Microarray expression analysis of TBX5/ GATA-4 double overexpression P19 cell lines led to the identification of a large number of genes, of which seven were selected for study; PA2.26, PETA-3, FUCA 1, FN, TPM1, DES, and RBMS1. Expression of these was confirmed in the embryonic chick heart at Hamburger and Hamilton (HH) stages 12 - 26. The cell cycle regulator and transcription factor RBMS1 was selected for investigation of its role in cardiac development. Morpholino knockdown of RBMS1 expression in the developing chick resulted in defects in cardiac looping and atrial septation. Whilst further work is required to strengthen this data, this is a novel finding and opens up possibilities for future research into cardiac transcriptional networks. Microarray expression analysis using an in ovo model of TBX5 and GATA-4 double knockdown led to the identification of a number of interesting putative targets, including TFAP2B, GPC3, and CRABP1, which have known roles in cardiac development. TFAP2B is of particular interest as mutations in this gene are associated with the heart-hand disorder Char syndrome. LOC420770, a novel gene of unknown function, was also identified and displayed expression indicative of a heart-limb profile. Further studies to attempt elucidation of the function of this gene may provide a novel candidate gene for CHD. Investigation of these genes will form the basis of future research, contributing to our current knowledge of the vast network of genes involved in development of the heart.

Cardiomyocyte apoptosis is an important contributory factor towards the progression of ischaemic heart disease. Signal Transducer and Activator of Transcription 3 (STAT3) is a transcription factor has that been implicated in normal heart development and function. Most interestingly, STAT3 also appears to play a role in cardioprotection, including hypoxic preconditioning. In this thesis the levels and activities of ST A T3 were measured in response to hypoxic insult in primary rat cardiomyocytes (RCMs) and two cardiomyocyte cell lines (H9c2 and P19CL6 cells). P19CL6 cells were extremely sensitive to hypoxia-induced apoptosis whereas RCMs and H9c2 cells were highly resistant. Apoptosis in P19CL6 cells correlated with loss of STAT3 DNA binding, which was preceded by serine phosphorylation and followed by loss of tyrosine phosphorylation. Treatment with LIF partially protected P19CL6 cells from hypoxia-induced apoptosis, as did exogenous expression of STAT3 but not a redox-insensitive ST AT3 mutant (STAT3C3s ). Moreover, STAT3 expression rescued mitochondrial ATP production during hypoxia whereas the redox-insensitive mutant did not. These data indicate that the contribution of STAT3 to cardiomyocyte survival under hypoxic stress involves the maintenance of mitochondrial function by a redox-dependent mechanism. Understanding how STAT3 is regulated in cardiomyocytes will be important for the development of therapeutic approaches for ischaemic heart disease in the future.

Background Routine induction of anaesthesia and maintenance haemodialysis are two examples of clinical procedures that exert a direct effect on the cardiovascular system. The exact incidence of haemodynamic instability during such procedures is not well described, as it would have required invasive intra-arterial monitoring, which is not justified for routine use. As part of two service evaluations, i.e. routine induction of anaesthesia and maintenance haemodialysis, we utilised a noninvasive continuous beat-by-beat haemodynamic monitor, which works using a finger cuff (Finometer), to assess the incidence of haemodynamic instability encountered during these procedures in comparison to the conventionally used intermittent noninvasive blood pressure (NIBP) measurement protocols. Methods Using the Finometer, we recorded haemodynamic variables during induction of anaesthesia in 100 patients undergoing elective surgery, and during maintenance haemodialysis in 25 patients with established renal failure. Firstly, we assessed the feasibility of using the Finometer during induction of anaesthesia and haemodialysis by evaluating its success rate in providing measurements of haemodynamic variables, and by assessing its accuracy in comparison to the readings obtained by the conventional NIBP devices during our service evaluations. Secondly, we assessed the incidence of haemodynamic instability during both procedures as detected by the Finometer in comparison to the existing conventional intermittent NIBP measurement protocols. Results and discussion The Finometer was successful in providing adequate haemodynamic monitoring in 96% and 86% of the attempts to use it in our service evaluations during induction of anaesthesia and haemodialysis respectively. The Finometer showed comparable accuracy in terms of BP monitoring to the conventional NIBP monitors during induction of anaesthesia and haemodialysis. A high incidence of significant hypotension as well as significant hypertension was shown during both, routine induction of anaesthesia and maintenance haemodialysis, which were underestimated or even missed by the conventionally used intermittent NIBP monitoring protocols. During induction of anaesthesia, 19% of the patients sustained an episode of hypotension defined as SBP less than 80 mmHg for more than 1 min, and 53% showed a transient increase of the SBP of more than 20% from baseline values. During Haemodialysis, 28% of the patients sustained an episode of hypotension defined as SBP less than 90 mmHg for more than 10 min, and 16% sustained an episode of severe hypertension defined as SBP more than 180 mmHg for more than 10 min. Conclusion Haemodynamic instability is commonly encountered during routine induction of anaesthesia and maintenance haemodialysis. Continuous noninvasive finger arterial haemodynamic monitoring is more reliable than the conventionally used protocols of intermittent NIBP monitoring in detecting such haemodynamic instability, thus providing higher levels of patient safety. Extra and early information about haemodynamic variables, as provided by the Finometer, may provide a better insight on the exact cause of haemodynamic instability, which may aid the physicians in prompt and targeted management.

Background: Patients with chronic kidney disease (CKD) face a markedly increased risk of cardiovascular morbidity and mortality. In this setting, aberrant endothelial function is a key initiating event in vascular disease. Haemodialysis (HD) patients characteristically exhibit significant abnormalities in vascular structure and function, which impact cardiovascular morbidity and mortality. Micro- and macro-vascular dysfunctions are the principle factors contributing to the increased risk of morbidity and mortality associated with obesity. Impaired endothelial function represents the earliest abnormality in the development of vascular disease in obesity and exhibits increased risk of cardiovascular disease. We first aimed to investigate the effect of HO and obesity on the vascular reactivity through directly examines the isolated subcutaneous arteries using wire myography. The second goal was to study changes that might underlie altered vascular responses following bariatric surgery and whether reduction in weight improves endothelial function. We also intended to correlate the ex vivo myography data with the in vivo results of pulse wave velocity (PWV) and blood pressure (BP) in both HO and obese patients. Methods: Abdominal subcutaneous fat biopsies were obtained from HO patients (n= l l ) during non-HO visits through small lower abdominal incisions using local anaesthetics; obese patients (n=12) during the time of bariatric surgery (using a laparoscopic port); and non-HD, non-obese healthy controls (n=26) during the time of elective surgery (hernia repair). Additional abdominal subcutaneous fat samples (n=4) were also obtained from obese patients at six months after bariatric surgery through an extra incision in the lower abdominal region using local anaesthetics. Different-sized arteries (small with internal diameter between 200 urn - 500 urn and large between 600 urn - 900 urn) were dissected, mounted and conducted on a wire myography on the same day. Cumulative concentration-response curves were constructed for the following vasoactive agents: noradrenalin (NA), endothelin-I (ET-I), U46619, angiotensin II (AngII), vasopressin, bradykinin (BK), acetylecholine (Ach) and sodium nitroprusside (SNP). Carotid-to-femoral arterial PWV was measured using an oscillometric device (Vicorder, Skidmore Medical Ltd., UK) for HD and obese patients in addition to measuring blood pressure (BP). Laboratory data were expressed as mean ± SEM and groups were compared by t-test. Results: In both HD and obese patients, greater contractile response to different vasoconstrictors was observed in different-sized arteries compared to control group. Although the potency of these drugs was similar between HD patients and controls, large vessels of HD patients were highly potent to U46619 and vasopressin compared to controls. Similarly, in obese patients, large vessels were also significantly more sensitive to U46619 and vasopressin than that of controls, while small vessels were highly potent to vasopressin response. The maximum vasorelaxation response of small and large vessels to Ach and BK (endothelium-dependent vasodilators) was significantly lower in both HD and obese patients than vessels of controls. A similar response to SNP (an endothelium-independent vasodilator) was obtained in all groups. However, the potencies of all vasodilators in all groups were similar. In HD patients, in vivo PWV was significantly correlated with the maximum contractile response of large arteries to vasopressin response (r = 0.829, P = 0.042). PWV was positively correlated with the percentage of maximum contractile response of small arteries to vasopressin (r = 0.886, P = 0.019). The diastolic but not systolic BP of HD patients was significantly inversely correlated with the response of large vessels to SNP (r = -0.954, P = 0.012), it was also negatively correlated with the percentage of contractile response of small arteries to vasopressin (r = -0.829, P = 0.042). There was no correlation observed in the responses of isolated small arteries to the other vasoconstrictor substances in terms of PWV or BP. In obese patients, The PWV was significantly correlated with the maximum contractile response of large arteries to U46619 (r = 0.928, P = 0.006), and with the maximum contractile response of small arteries to vasopressin (r = 0.885, P = 0.033).However, positive correlation was obtained between systolic (but not diastolic BP) of obese patients and the response of large vessels to U46619 (r = 0.785, P = 0.048). There was no significant difference in the vasocontractile or vasorelaxation responses of isolated vessels in obese patients before and after surgery; however, a trend of more contractile response to vasoconstrictors was observed in the obese group before surgery compared to those after surgery. Conclusion: These results suggest that HO and obesity can alter endothelial function via an incremental increase in vasocontractility in response to various stimuli and an impaired vasodilatation response to endothelium-dependent agonists in isolated different-sized vessels. In both groups, ex vivo arterial responses were correlated to in vivo assessment of arterial function. The association between these risk groups and endothelial dysfunction in isolated arteries would be expected to accelerate cardiovascular events, which impacts cardiovascular morbidity and mortality among these groups of patients. Therefore. the development of cardiovascular disease is mediated, at least partly, by functional alterations at the level of microcirculation.

ATP has been shown to be a sympathetic neurotransmitter in blood vessels. However, its relative importance has been shown to be influenced by the experimental conditions employed such as alteration of the vascular tone. Thus the main aim was to raise the tone of vascular preparations and to further examine sympathetic neurotransmission in these preparations. Porcine whole mesenteries were perfused with physiological buffer and changes in pressure recorded or different sized mesenteric arteries were isolated and set up for isometric recording. Responses to electrical field stimulation (EFS) were obtained under basal and raised tone conditions induced by U46619, a thromboxane A2 mimetic. The nature of the neurotransmitters involved in the mediation of the electrically-evoked responses was assessed using an α1-adrenoceptor antagonist, prazosin and/or the P2X receptor desensitizing agent, α,β-methyleneATP, an α2-adrenoceptor RX811059 antagonist, and a neuropeptide Y Y1 receptor antagonist BIBP3226. In separate experiments, responses to nerve stimulation were investigated in rat mesenteric small arteries pressurized to 90 mmHg. The effects of a selective α1-adrenoceptor antagonist, YM-12617, and selective P2X1 receptor antagonist, NF-449, on the electrically-evoked response were determined. Under basal tone conditions the electrically-evoked contractile responses in porcine whole mesenteric bed and isolated arteries were exclusively mediated by noradrenaline (NA) since they were inhibited by prazosin. However, under conditions of raised tone, the electrically-evoked responses were enhanced and a role for ATP was evident since these responses were sensitive to α,β-methyleneATP. Responses to exogenous NA and α,β-methyleneATP were also enhanced at raised tone indicating a postjunctional mechanism of enhancement. Nifedipine attenuated the enhanced responses to EFS and α,β-methyleneATP suggesting a possible role for L-type calcium channels in the mediation of the enhanced responses. In rat pressurised mesenteric arteries the electrically-evoked vasocontractile responses were sensitive to YM-12617 and NF-449, indicating that NA and ATP were involved in the mediation of these responses. Raising tone with U46619 in these arteries enhanced the electrically-evoked contractile response; under these conditions responses were sensitive to both YM-12617 and NF-449. The present study supports the observation that ATP becomes a more important sympathetic neurotransmitter under conditions of raised tone in contrast to when tone is absent. In porcine mesenteric vascular preparations NA predominates as the main sympathetic neurotransmitter under conditions of basal tone. However, when tone was raised the responses were enhanced and a role for ATP became evident.