Christopher S Hayward

Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia

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Publications (132)718.91 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Primary graft dysfunction (PGD) is a life-threatening complication of heart transplantation that presents as left, right, or biventricular dysfunction occurring within the first 24 hours of transplant surgery for which there is no identifiable secondary cause. Myocardial injury caused by acute catecholamine toxicity and the release of multiple proinflammatory mediators in the donor, followed by ischaemia-reperfusion injury sustained during retrieval, have been considered the predominant pathogenetic processes leading to PGD. Donor, recipient, and procedural factors contribute to the development and severity of the clinical syndrome. The changing donor and recipient characteristics over the last two decades, particularly the increasing donor and recipient age, have led to heightened risk of PGD. PGD is graded from mild to severe depending on the extent of circulatory support that is required to maintain haemodynamic stability and vital organ function. While advances in acute mechanical support devices have improved the outlook for patients with PGD, the rate of mortality remains high for those with severe PGD, reaching 40 %. Potential approaches to preventing or minimising the severity of PGD include optimising donor management, donor heart preservation, and donor/recipient matching.
    Current Transplantation Reports. 12/2014; 1(4).
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    ABSTRACT: Heart transplantation is limited by donor organ availability. Increased use of marginal donor organs, combined with increased recipient complexity, has increased the risk of primary graft failure. These changes in donor and recipient characteristics have led to a renewed focus on modifiable donor–recipient characteristics that have historically been shown to impact on post-transplant outcomes, namely size and gender matching. Recently published analyses of large registries have found that the use of body weight to size donor organs for transplantation fails to predict post-transplant outcomes, whereas newer methods such as predicted heart mass (utilizing height, age, and gender as well as weight) correlate well with a number of post-transplant outcomes, including survival. The well recognized risks of under-sizing in female donor:male recipient transplants and in recipients with increased pulmonary vascular resistance are reinforced by recent studies. Over-sizing is not associated with increased risk or survival benefit versus ideally matched adult donor hearts.
    Current Transplantation Reports. 12/2014; 1(4).
  • The Journal of Heart and Lung Transplantation 11/2014; · 5.61 Impact Factor
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    ABSTRACT: Aims and objectivesThis review will (1) explore factors related to thirst in chronic heart failure and (2) describe interventions to alleviate thirst in chronic heart failure patients.Background Thirst is a common and troublesome symptom of chronic heart failure. Despite the burden and prevalence of this symptom, there are limited strategies to assist in its management.DesignThis is a review of literature on the burden of thirst, contributors to thirst and potential management strategies of thirst in patients with chronic heart failure.Methods Medline, Cumulative Index for Nursing and Allied Health, PubMed and Scopus were searched using the key words thirst, chronic heart failure, angiotensin II, fluid restriction and intervention. Of the 165 citations yielded, nine studies (n = 9) were included. The eligibility criteria included participants with confirmed diagnosis of chronic heart failure, randomised controlled studies or any studies with thirst as primary or secondary outcome, in humans and in English. There was no limit to the years searched.ResultsFactors related to thirst in chronic heart failure were condition; prolonged neurohormonal activation, treatment; pharmacological interventions and fluid restriction and emotion. No intervention studies were found in chronic heart failure patients. Interventions such as artificial saliva and chewing gum have been investigated for their effectiveness as a thirst reliever in haemodialysis patients.Conclusion Thirst is a frequent and troublesome symptom for individuals with chronic heart failure. It is highly likely that this contributes to poor adherence with fluid restrictions. Chewing gum can help alleviate thirst, but investigation in people with heart failure is needed.Relevance to clinical practiceIncreasing awareness of thirst and interventions to relieve it in clinical practice is likely to improve the quality of care for people with chronic heart failure.
    Journal of Clinical Nursing 11/2014; · 1.23 Impact Factor
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    ABSTRACT: The study sought to assess feasibility, safety, and potential efficacy of a novel implantable extra-aortic counterpulsation system (C-Pulse) in functional class III and ambulatory functional class IV heart failure (HF) patients.
    JACC. Heart failure. 10/2014; 2(5):526-33.
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    ABSTRACT: Background New generation continuous-flow left ventricular assist devices (LVADs) utilise centrifugal pumps. Data concerning their effect on patient haemodynamics, ventricular function and tissue perfusion is limited. We aimed to document these parameters following HeartWare centrifugal continuous-flow LVAD (HVAD) implantation and to assess the impact of post-operative right heart failure (RHF). Methods We reviewed 53 consecutive patients (mean age 49.5 ± 14.1yrs) with HVAD implanted in the left ventricle, at St. Vincent's Hospital, Sydney, between January 2007 and August 2012. Available paired right heart catheterisation (n = 35) and echocardiography (n = 39) data was reviewed to assess response of invasive haemodynamics and ventricular function to LVAD support. Results A total of 28 patients (53%) were implanted from interim mechanical circulatory support. Seventeen patients (32%) required short-term post-implant veno-pulmonary artery extracorporeal membrane oxygenation. At 100 ± 61 days post-implant, mean pulmonary artery pressure and mean pulmonary capillary wedge pressure decreased from 38.8 ± 7.7 to 22.9 ± 7.7 mmHg and 28.3 ± 6.4 to 13.4 ± 5.4 mmHg respectively (p < 0.001). LV end diastolic diameter decreased from 71.3 ± 12.7 to 61.1 ± 13.7 mm and LV end-systolic diameter from 62.7 ± 12.3 to 53.9 ± 14.4 mm (p < 0.001). Aortic regurgitation remained trivial. Serum sodium increased from 133.3 ± 5.7 to 139.3 ± 2.8 mmol/L and creatinine decreased from 109.1 ± 42.5 to 74.3 ± 26.2 μmol/L (p < 0.001). Across the entire cohort, the six-month survival/transplant rate was significantly lower for RHF patients (72.2%, n = 18) compared to those without (96.9%, n = 35, p = 0.01). Conclusions HVAD support improves haemodynamics, LV dimensions and renal function. Following implantation with a centrifugal continuous-flow LVAD, RHF remains a significant risk with a tendency to worse outcomes in the short to medium term.
    Heart Lung &amp Circulation 10/2014; · 1.17 Impact Factor
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    ABSTRACT: Background Improved survival of heart transplant (HTx) recipients and increased acceptance of higher risk donors allows development of late pathology. However, there are few data to guide surgical options. We evaluated short-term outcomes and mortality to guide pre-operative assessment, planning, and post-operative care. Methods Single centre, retrospective review of 912 patients who underwent HTx from February 1984 - June 2012, identified 22 patients who underwent subsequent cardiac surgery. Data are presented as median (IQR). Results Indications for surgery were coronary allograft vasculopathy (CAV) (n = 10), valvular disease (n = 6), infection (n = 3), ascending aortic aneurysm (n = 1), and constrictive pericarditis (n = 2). There was one intraoperative death (myocardial infarction). Hospital stay was 10 (8-21) days. Four patients (18%) returned to theatre for complications. After cardiac surgery, survival at one, five and 10 years was 91 ± 6%, 79 ± 10% and 59 ± 15% with a follow-up of 4.6 (1.7-10.2) years. High pre-operative creatinine was a univariate risk factor for mortality, HR = 1.028, (95%CI 1.00-1.056; p = 0.05). A time dependent Cox proportional hazards model of the risk of cardiac surgery post-HTx showed no significant hazard; HR = 0.87 (95%CI 0.37-2.00; p = 0.74). Conclusions Our experience shows cardiac surgery post-HTx is associated with low mortality, and confirms that cardiac surgery is appropriate for selected HTx recipients.
    Heart Lung &amp Circulation 08/2014; · 1.17 Impact Factor
  • The Journal of Heart and Lung Transplantation 08/2014; · 5.61 Impact Factor
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    ABSTRACT: Objectives The aim of this study was to determine the contribution of pre-load and heart rate to pump flow in patients implanted with continuous-flow left ventricular assist devices (cfLVADs). Background Although it is known that cfLVAD pump flow increases with exercise, it is unclear if this increment is driven by increased heart rate, augmented intrinsic ventricular contraction, or enhanced venous return. Methods Two studies were performed in patients implanted with the HeartWare HVAD. In 11 patients, paced heart rate was increased to approximately 40 beats/min above baseline and then down to approximately 30 beats/min below baseline pacing rate (in pacemaker-dependent patients). Ten patients underwent tilt-table testing at 30°, 60°, and 80° passive head-up tilt for 3 min and then for a further 3 min after ankle flexion exercise. This regimen was repeated at 20° passive head-down tilt. Pump parameters, noninvasive hemodynamics, and 2-dimensional echocardiographic measures were recorded. Results Heart rate alteration by pacing did not affect LVAD flows or LV dimensions. LVAD pump flow decreased from baseline 4.9 ± 0.6 l/min to approximately 4.5 ± 0.5 l/min at each level of head-up tilt (p < 0.0001 analysis of variance). With active ankle flexion, LVAD flow returned to baseline. There was no significant change in flow with a 20° head-down tilt with or without ankle flexion exercise. There were no suction events. Conclusions Centrifugal cfLVAD flows are not significantly affected by changes in heart rate, but they change significantly with body position and passive filling. Previously demonstrated exercise-induced changes in pump flows may be related to altered loading conditions, rather than changes in heart rate.
    JACC: Heart Failure. 08/2014;
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    ABSTRACT: Abstract Background: Thirst is a bothersome symptom of chronic heart failure (CHF) which impacts adversely on quality of life. Despite this, limited work has been done to investigate thirst as a symptom or to develop reliable and valid measures of thirst in CHF. The purpose of this manuscript is to establish which tools have been used in research to measure thirst in CHF. Methods: Medline, PubMed, CINAHL, and Scopus were searched using following key words thirst, heart failure, measure, scale, randomised controlled trials and multicentre studies. Results: The search discovered 37 studies of which 6 studies met the inclusion criteria. One study was a research abstract and five were full- text studies. To date, there are only three measurement tools utilised in studies examining thirst in CHF patients (Visual Analogue Scale, Numeric Rating Scale and Thirst Distress Scale). Conclusion: Thirst in CHF is measured in a non- systematic way. In recent studies, the VAS has been used to measure thirst intensity. While this measurement tool is very easy and quick to administer, using a uni-dimensional tool in conjunction with a multi-dimensional tool may be beneficial to capture all dimensions of thirst. In order to manage thirst efficiently, consistent measurement of thirst in CHF is vital.
    Contemporary nurse: a journal for the Australian nursing profession 07/2014; · 0.65 Impact Factor
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    ABSTRACT: Six-minute walk distance (6MWD) and maximal oxygen uptake (VO2 max ) are used as prognostic tools in patients with heart failure (HF). Whether these tests provide similar information in the LVAD population is not known.
    The International journal of artificial organs 07/2014; · 1.45 Impact Factor
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    ABSTRACT: It is important to accurately monitor residual cardiac function in patients under long-term continuous-flow left ventricular assist device (cfLVAD) support. Two new measures of left ventricular (LV) chamber contractility in the cfLVAD-unloaded ventricle include IQ , a regression coefficient between maximum flow acceleration and flow pulsatility at different pump speeds; and K, a logarithmic relationship between volumes moved in systole and diastole. We sought to optimize these indices. We also propose RIQ , a ratio between maximum flow acceleration and flow pulsatility at baseline pump speed, as an alternative to IQ . Eleven patients (mean age 49 ± 11 years) were studied. The K index was derived at baseline pump speed by defining systolic and diastolic onset as time points at which maximum and minimum volumes move through the pump. IQ across the full range of pump speeds was markedly different between patients. It was unreliable in three patients with underlying atrial fibrillation (coefficient of determination R(2) range: 0.38-0.74) and also when calculated without pump speed manipulation (R(2) range: 0.01-0.74). The K index was within physiological ranges, but poorly correlated to both IQ (P = 0.42) and RIQ (P = 0.92). In four patients there was excellent correspondence between RIQ and IQ , while four other patients showed a poor relationship between these indices. As RIQ does not require pump speed changes, it may be a more clinically appropriate measure. Further studies are required to determine the validity of these indices.
    Artificial Organs 03/2014; · 1.87 Impact Factor
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    ABSTRACT: Abstract Background: Thirst is a bothersome symptom of chronic heart failure (CHF) which impacts adversely on quality of life. Despite this, limited work has been done to investigate thirst as a symptom or to develop reliable and valid measures of thirst in CHF. The purpose of this manuscript is to establish which tools have been used in research to measure thirst in CHF. Medline, PubMed, Cumulative Index for Nursing and Allied Health, and Scopus were searched using following key words thirst, heart failure, measure, scale, randomised controlled trials and multicentre studies. The search discovered 37 studies of which 6 studies met the inclusion criteria. One study was a research abstract and five were full-text studies. To date, there are only three measurement tools utilised in studies examining thirst in CHF patients [Visual Analogue Scale (VAS), Numeric Rating Scale and Thirst Distress Scale]. Thirst in CHF is measured in a non-systematic way. In recent studies, the VAS has been used to measure thirst intensity. While this measurement tool is very easy and quick to administer, using a uni-dimensional tool in conjunction with a multi-dimensional tool may be beneficial to capture all dimensions of thirst. In order to manage thirst efficiently, consistent measurement of thirst in CHF is vital.
    Contemporary nurse. 01/2014; 48(1):2-9.
  • The International journal of artificial organs 07/2013; 36(7):449-54. · 1.45 Impact Factor
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    ABSTRACT: BACKGROUND: -The transcription factor NKX2-5 is crucial for heart development and mutations in this gene have been implicated in diverse congenital heart diseases (CHD) and conduction defects (CD) in mouse models and humans. Whether NKX2-5 mutations have a role in adult-onset heart disease is unknown. METHODS AND RESULTS: -Mutation screening was performed in 220 probands with adult-onset dilated cardiomypathy (DCM). Six NKX2-5 coding sequence variants were identified, including 3 non-synonymous variants. A novel heterozygous mutation, I184M, located within the NKX2-5 homeodomain (HD), was identified in one family. A subset of family members had CHD, but there was an unexpectedly high prevalence of DCM. Functional analysis of I184M in vitro demonstrated a striking increase in protein expression when transfected into COS-7 cells or HL-1 cardiomyocytes, due to reduced degradation by the ubiquitin-proteasome system (UPS). In functional assays, DNA binding activity of I184M was reduced, resulting in impaired activation of target genes, despite increased expression levels of mutant protein. CONCLUSIONS: -Certain NKX2-5 HD mutations show abnormal protein degradation via the UPS and partially impaired transcriptional activity. We propose that this class of mutation can impair heart development and mature heart function, and contribute to NKX2-5-related cardiomyopathies with graded severity.
    Circulation Cardiovascular Genetics 05/2013; · 5.34 Impact Factor
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    ABSTRACT: This multicenter study examines in detail the spontaneous increase in pump flow at fixed speed that occurs in exercise. Eight patients implanted with the VentrAssist rotary blood pump were subjected to maximal and submaximal cycle ergometry studies, the latter being completed with patients supine and monitored with right heart catheter and echocardiography. Maximal exercise studies conducted in each patient at three different pump speeds on separate days established initially the magnitude and consistency of increases in pump flow that correlated well with changes in heart rate. However, there was considerable variation, coefficients of variation for mean heart rate and pump flow being 47.9 and 49.3%, respectively. Secondly, these studies indicated that increasing pump flows caused significant improvements in maximal exercise capacity. An increase of 2.1 L/min (35%) in maximum blood flow caused 12 W (16%) further increase in achievable work, 1.26 (9.3%) mL/kg/min in maximal oxygen uptake, and 2.3 (23%) mL/kg/min in anaerobic threshold. Mean increases in lactate were 0.85 mm (24%), but mean B-type natiuretic peptide fell by 126 mm, (-78%). From submaximal supine exercise studies, multiple linear regression of pump flow on factors thought to underlie the spontaneous increase in pump flow indicated that it was associated with increases in heart rate (P = 0.039), pressure gradient across the left ventricle (P = 0.032), and right atrial pressure (P = 0.003). These changes have implications for the recently reported Starling-like controller for pump flow based on pump pulsatility values, which emulates the Starling curve relating pump output to left ventricular preload. Unmodified, the controller would not permit the full benefits of this effect to be afforded to patients implanted with rotary blood pumps. A modification to the pump control algorithm is proposed to eliminate this problem.
    Artificial Organs 05/2013; · 1.87 Impact Factor
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    ABSTRACT: Purpose The HeartWare Ventricular Assist Device (HVAD) is an implantable, continuous-flow centrifugal pump with a magnetically and hydro-dynamically suspended impeller capable of delivering flows of up to 10L/min. Although clinicians routinely listen over the HVAD with a stethoscope, there is no literature on a systematic analysis of audiosignals generated by the implanted pump.This study explores the HVAD audiosignals produced across a variety of pump and haemodynamic scenarios. Methods and Materials A wireless stethoscope was used to record pump audiosignals in 7 Left and 2 Bi-Ventricular HVAD recipients. Welch Power Density Spectral Analysis was used to determine the frequency content of recorded pump audiosignals and also to correlate these signals with both clinical events as well as with the stored pump parameter data. The nature of the audiosignals under a range of pressure, speed and fluid viscosity scenarios were assessed in a HVAD Mock Loop circulation model. Results Spectral analysis revealed the presence of a signature audiosignal for the HVAD in the form of 2 frequency peaks that are independent of pump and haemodynamic conditions. Pump speed determined the frequency peak position in VAD recipients and in the Mock Loop studies, while Mean Arterial Pressure (MAP) appeared to influence the 2 peak’s power density (R²=0.697, P=0.019 & R²=0.857, P=0.003). Audiosignal production in 2 BiVAD patients with outflow graft thrombus was described pre and post thrombolytic therapy. Changes in fluid viscosity altered peak height of this signature in Mock Loop recordings. Conclusions Audiosignals from HVAD pump impellers can be recorded using wireless technology. Spectral analysis of these audiosignals reveals pump-specific frequency peaks in VAD recipients and Mock Loop scenarios which show a relationship with pump settings and patient haemodynamic status. We believe that audiosignal profiling of implantable VADs may offer a novel approach to assess pump function and may even provide an early diagnostic tool for pump related complications.
    The Journal of Heart and Lung Transplantation 04/2013; 32(4):S30. · 5.61 Impact Factor
  • M. Connellan, K. Muthiah, D. Robson, E. Granger, K. Dhital, P. Spratt, C. Hayward, P. Jansz
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    ABSTRACT: The outflow graft of the HeartWare HVAD lies with a curve to allow for connection of the device to the ascending aorta. We aimed to quantify the potential haemodynamic significance of an acute bend in the outflow graft and ascertain the validity of the reported HVAD flows under these conditions.Methods and MaterialsAn HVAD in vitro circuit with 10mm gelatin-sealed woven polyester outflow graft was run using a 30% Glycerol solution. After baseline measurements were taken, the graft was angulated at 30,60,90,100,110,130,140,150 and180°. Pump power, flow, pre- and post-angulation pressures and measured circuit flows were recorded at each angulation point. This was done for pump speeds of 2400rpm, 2800rpm and 3200rpm. For comparison, these sequences were repeated using a 10mm ePTFE graft.ResultsA pressure gradient of 10mmHg developed across the kink when the graft was angulated beyond 90°, 130° and 140°, at speeds of 3200rpm, 2800rpm and 2400rpm respectively. [figure 1] Despite this, flow was largely maintained and at 180° angulation, decreased by only 5%, 6% and 12% from baseline, for the above respective speeds. The reported HVAD flows correlated well with measured flows throughout the angulation range (r=0.981). The ePTFE conduit permitted less flow with a greater pressure gradient than the polyester graft.ConclusionsA kink in the outflow graft seems unlikely to result in a clinically relevant decrease in HVAD flow. Significantly however, progressive angulation of the graft does result in increasing pressure gradients and decreased arterial perfusion pressures. The algorithmically calculated HVAD flows seem to give an accurate estimation of true flow under these conditions.
    The Journal of Heart and Lung Transplantation 04/2013; 32(4):S280. · 5.61 Impact Factor
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    ABSTRACT: LVADs are increasingly being used to support patients with end stage heart failure. As such, the traditional definition of death, the absence of a pulse, requires re-examination as it is no longer clinically relevant. We present two contrasting cases of "death" on LVAD support and present some ethical issues surrounding the end of life on LVAD support.
    Heart Lung &amp Circulation 03/2013; · 1.17 Impact Factor
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    ABSTRACT: OBJECTIVE: Studies have shown that pump output by continuous-flow left ventricular assist devices (LVADs) increases with graded exercise testing. However, data on pump behavior during activities of daily living and sleep, where cardiac output requirements vary markedly, are lacking. We sought to determine pump parameters and activity levels in stable patients receiving outpatient LVAD therapy. METHODS AND RESULTS: Eleven outpatients (mean age 51 ± 14 years, 9 male) with centrifugal continuous-flow LVADs underwent monitoring of LVAD flow, heart rate (HR), energy expenditure, and physical activity over 1 week in an outpatient setting. Physical activity was recorded with the use of a combined pedometer, accelerometer, and calorimeter Sensewear armband. Pump, HR, and physical activity parameters were time matched for correlation analysis. Outpatients had an average pump flow of 5.67 ± 1.27 L/min and engaged predominately in low levels of physical activity (mean daily step count 3,249/day). Across the entire cohort, pump flow exhibited strong univariate relationships with patients' energy expenditure (r = 0.73), step count (r = 0.69), HR (r = 0.73), sleep (r = -0.89), and skin temperature (r = -0.85; P < .0001 for all). Multivariate analysis suggested that pump output was predominantly affected by recumbent position, energy expenditure and skin temperature (r2 = 0.84; P < .0001). Pump flow and power consumption were significantly lower during sleep than during wake periods (5.48 ± 1.31 L/min vs 5.80 ± 1.26 L/min; P < .001). CONCLUSIONS: Pump output from continuous-flow LVADs is adaptive to changes in activities of daily living. Circadian variation in pump flow is mostly explained by recumbency and activity levels. Despite adequate pump flow, many LVAD patients continue to live sedentary lifestyles.
    Journal of cardiac failure 03/2013; 19(3):169-175. · 3.07 Impact Factor

Publication Stats

2k Citations
718.91 Total Impact Points

Institutions

  • 2003–2014
    • Victor Chang Cardiac Research Institute
      Darlinghurst, New South Wales, Australia
  • 2001–2014
    • Saint Vincent Hospital
      Worcester, Massachusetts, United States
  • 1997–2013
    • St. Vincent's Hospital Sydney
      • Department of Cardiology
      Sydney, New South Wales, Australia
  • 2011
    • University of New South Wales
      • St Vincent's Clinical School
      Kensington, New South Wales, Australia
  • 1999–2008
    • Imperial College London
      • • Faculty of Medicine
      • • National Heart and Lung Institute
      Londinium, England, United Kingdom
  • 2007
    • St Vincent’s Private Hospital (Australia)
      Sydney, New South Wales, Australia
  • 2001–2006
    • Royal Brompton and Harefield NHS Foundation Trust
      Harefield, England, United Kingdom
  • 1999–2002
    • National Heart, Lung, and Blood Institute
      Maryland, United States