Peter N Ruygrok

Auckland District Health Board, Окленд, Auckland, New Zealand

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Publications (212)685.44 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Confocal laser scanning microscopy and super-resolution microscopy provide high-contrast and high-resolution fluorescent imaging, which has great potential to increase the diagnostic yield of endomyocardial biopsy (EMB). EMB is currently the gold standard for identification of cardiac allograft rejection, myocarditis, and infiltrative and storage diseases. However, standard analysis is dominated by low-contrast bright-field light and electron microscopy (EM); this lack of contrast makes quantification of pathological features difficult. For example, assessment of cardiac allograft rejection relies on subjective grading of H&E histology, which may lead to diagnostic variability between pathologists. This issue could be solved by utilising the high contrast provided by fluorescence methods such as confocal to quantitatively assess the degree of lymphocytic infiltrate. For infiltrative diseases such as amyloidosis, the nanometre resolution provided by EM can be diagnostic in identifying disease-causing fibrils. The recent advent of super-resolution imaging, particularly direct stochastic optical reconstruction microscopy (dSTORM), provides high-contrast imaging at resolution approaching that of EM. Moreover, dSTORM utilises conventional fluorescence dyes allowing for the same structures to be routinely imaged at the cellular scale and then at the nanoscale. The key benefit of these technologies is that the high contrast facilitates quantitative digital analysis and thereby provides a means to robustly assess critical pathological features. Ultimately, this technology has the ability to provide greater accuracy and precision to EMB assessment, which could result in better outcomes for patients.
    Heart Failure Reviews 08/2014; · 4.45 Impact Factor
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    ABSTRACT: We report a case of a 79-year-old man with hemolytic anemia caused by a small paravalvular leak after aortic valve replacement with mechanical prosthesis. The defect was successfully treated with a vascular plug.
    Journal of Cardiovascular Medicine 08/2014; · 2.66 Impact Factor
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    ABSTRACT: Aims Primary percutaneous coronary intervention (PCI) is the optimal management for ST segment elevation myocardial infarction (STEMI) patients. We reviewed the largest primary PCI regional service in New Zealand: the Auckland/Northland service based at Auckland City Hospital, to assess patient management, in particular the door to reperfusion times (DTRTs), and predictors of death in hospital. Methods We obtained patient details from a comprehensive prospective database of all primary PCI patients admitted with STEMI from 1/1/12 to 31/12/12 to the Auckland City Hospital cardiac catheterisation laboratory. Of four District Health Boards (DHBs) within the region, two accessed this regional service at all times, and two accessed the Auckland City Hospital cardiac catheterisation laboratory ‘after hours’: all times except for 08:00 to 16:00 hours on Monday to Friday. Results A total of 401 adult patients underwent a primary PCI at the Auckland City Hospital Regional centre for a STEMI presentation, over the 12 months period. The median patient age was 61 years, 77% were male. Overall 183 (46%) (95% CI 41, 51) patients achieved a DTRT of ≤ 90 mins, and 266 (66%) (95% CI 61, 71) a DTRT of ≤ 120mins, with a clear geographical influence to these times. Of 27 patients with direct transfer to the catheter laboratory from the community, the DTRT was ≤ 120 mins in 24 (92%) (95% CI 72, 96) patients. In hospital mortality was 24 (6%) patients (95% CI 4, 9). Conclusions The 2012 Auckland/Northland primary PCI service delivers good outcomes consistent with current Australasian standards. Although geographical isolation complicates door to reperfusion times, these may potentially be improved by more focus on direct transfer to the cardiac catheterisation laboratory, especially directly from the community.
    Heart Lung &amp Circulation 07/2014; · 1.25 Impact Factor
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    ABSTRACT: Atrial fibrillation (AF) is the commonest cardiac arrhythmia, becoming increasingly prevalent as the population ages. There is conflicting information around whether AF is associated with adverse outcomes after aortic valve replacement (AVR) from the few studies that have investigated this. We compared the characteristics and outcomes of patients undergoing AVR with their history of AF. Isolated AVR patients at Auckland City Hospital 2005-2012 were divided into those with and without preoperative AF for comparative analyses. Of 620 consecutive patients, 19.2% (119) had permanent or paroxysmal AF preoperatively. Patients with AF were significantly older (70.5 vs 63.4 years, P < 0.001) and were more likely to be New Zealand European (82.4 vs 68.1%, P = 0.004). They also had higher prevalence of NYHA class III-IV (55.4 vs 37.4%, P = 0.004), inpatient operation (62.1 vs 48.3%, P = 0.008), history of stroke (10.9 vs 5.0%, P = 0.031), lower creatinine clearance (73 vs 82, P = 0.001) and higher EuroSCORE II (5.2 vs 3.4%, P < 0.001). Operative mortality (6.7 vs 2.0%, P = 0.012) and composite morbidity (27.7 vs 16.5%, P = 0.006) were also higher in patients with AF. After adjusting for significant variables, preoperative AF remained an independent predictor of operative mortality with an odds ratio of 3.44 (95% confidence interval 1.29-9.13), composite morbidity of 1.79 (1.05-3.04) and a mortality during follow-up hazards ratio of 2.36 (1.44-3.87). AF was associated with several cardiovascular and cardiac surgery risk factors, but remained independently associated with short- and long-term mortality. AF should be incorporated into cardiac surgery risk models and surgical AF ablation may be considered with AVR.
    Interactive Cardiovascular and Thoracic Surgery 05/2014; · 1.11 Impact Factor
  • Heart Lung &amp Circulation 05/2014; · 1.25 Impact Factor
  • Heart Lung &amp Circulation 05/2014; · 1.25 Impact Factor
  • Heart Lung &amp Circulation 05/2014; · 1.25 Impact Factor
  • Heart Lung &amp Circulation 05/2014; · 1.25 Impact Factor
  • Heart Lung &amp Circulation 05/2014; · 1.25 Impact Factor
  • Heart Lung &amp Circulation 05/2014; · 1.25 Impact Factor
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    ABSTRACT: Objective Risk stratification for aortic valve replacement (AVR) is desirable given the increased demand for intervention and the introduction of transcatheter aortic valve implantation. We compared the prognostic utility of EuroSCORE, EuroSCORE II, Society of Thoracic Surgeon’s (STS) Score and an Australasian model (Aus-AVR Score) for AVR. Methods We retrospectively calculated the four risk scores for patients undergoing isolated AVR at Auckland City Hospital during 2005-2012, and assessed their discrimination and calibration for short and long-term mortality. Results A total of 620 patients were followed-up for 3.8+/-2.4 years, with operative mortality of 2.9% (18). The mean EuroSCORE, EuroSCORE II, STS Score and Aus-AVR Scores were 8.7%+/-8.3%, 3.8%+/-4.7%, 2.8%+/-2.7%, 3.2%+/-4.8%. C-statistics and 95% confidence intervals for operative mortality were 0.752 (0.652-0.852), 0.711 (0.607-0.815), 0.716 (0.593-0.837) and 0.684 (0.557-0.811). Hosmer-Lemeshow test P-values (χˆ2) for calibration were 0.007 (21.1), 0.125 (12.6), 0.753 (5.0) and 0.468 (7.7), while the Brier Scores were 0.0348, 0.0278, 0.0276 and 0.0294. Independent predictors of operative mortality included critical pre-operative state, atrial fibrillation, extracardiac arteriopathy and mitral stenosis. Log-rank test P-values were all <0.001 for mortality during follow-up for all four scores by quintiles. Conclusions All four risk scores discriminated operative mortality after isolated AVR. The EuroSCORE had poor calibration over-estimating operative mortality, whilst the other three scores fitted well with contemporary outcomes. The STS score was the best calibrated in the highest quintile of operative risk.
    Journal of Thoracic and Cardiovascular Surgery 04/2014; · 3.53 Impact Factor
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    ABSTRACT: To describe the indications and outcomes for pediatric patients and patients with congenital heart disease (CHD) undergoing heart transplantation (HT) in New Zealand. A retrospective audit of 253 patients who underwent HT from 1987 to end 2012 was undertaken. Thirty-seven patients were subdivided into two groups, those aged <18 years-pediatric heart disease (PHD) and those with CHD. Six patients aged <18 years were included in both the analyses. Demographic and clinical information were collected and outcomes established. Overall actuarial survival of 37 patients with PHD or CHD was 92% at one year, 85% at five years, and 52% at ten years. The PHD group comprised 22 (8.7%) patients, median age 14 years (range 6-17), 14 (64%) male, with cardiomyopathy in 13, CHD in 6, and rheumatic heart disease in 3. At follow-up, 11 patients had died. Actuarial survival was 91% at one year and 79% at five years. Of the four patients with a mechanical assist device to bridge, three were transplanted and alive at follow-up. The CHD group comprised 21 (8.3%) patients, median age 25 years (range 6-48) and 19 (90%) were male. At follow-up, three patients had died. Actuarial survival was 95% at one year, 94% at five years, and 85% at ten years. All five patients with pre-HT Fontan circulation were alive a median of eight years following HT. Heart transplantation for carefully selected pediatric patients and patients with CHD can be successfully performed with favorable outcomes in a geographically isolated unit.
    World journal for pediatric & congenital heart surgery. 04/2014; 5(2):200-5.
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    ABSTRACT: Cardiac troponins are the preferred biomarkers for diagnosing myocardial infarction (MI). High-sensitivity troponin T (hs-TnT) assays have increased sensitivity and enable more rapid diagnosis of infarction. We assessed the prognostic utility of admission hs-TnT to detect outcomes after primary angioplasty for ST-elevation/new left bundle branch block myocardial infarction (STEMI). Patients admitted to Auckland City Hospital for acute coronary catheterization with a diagnosis of STEMI between October 2010 and September 2011 were identified, and included if hs-TnT levels were measured at admission. Clinical characteristics and major adverse cardiovascular events (MACE: death, myocardial infarction and revascularization) at 30 days and 1 year were collected from national statistics and electronic medical records. Median admission hs-TnT level in the 173 STEMI patients studied was 59 ng/L (interquartile range (IQR) 19-310). Incidences of MACE at 30 days and 1 year were 10% (n=17) and 18% (n=31), respectively. C-statistics and 95% confidence interval (CI) (95% CI) for hs-TnT on admission at detecting MACE at 30 days and 1 year were 0.800 (0.696-0.904) and 0.750 (0.655-0.845) respectively, with the optimal cut-point of 225 ng/L giving sensitivities/specificities of 76.5%/75.6% and 64.5%/78.2% respectively. Admission log(hs-TnT) independently predicted both MACE at 30 days with hazards ratio 5.16, 95% CI (2.25-11.9) and 1 year with hazards ratio 2.88, 95% CI (1.79-4.63), as did age and cardiogenic shock. Age, Maori or Pacific ethnicity and chronic respiratory disease were independent predictors of hs-TnT>225 ng/L. Admission hs-TnT measured in primary angioplasty is strongly prognostic of MACE at 30 days and 1 year, even following adjustment for potential confounding variables.
    European heart journal. Acute cardiovascular care. 02/2014;
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    ABSTRACT: Cardiac implantable electronic devices (CIEDs) have now become common therapeutic adjuncts for patients prior to orthotopic heart transplantation (OHT). Removal of the generator and the intracardiac components occurs at time of transplantation but removal of the intravascular portion of leads may be unsuccessful without specialized extraction equipment. We performed a retrospective audit of chest radiographs and clinical records of patients undergoing OHT at Green Lane and Auckland City Hospitals between 2002 and 2012. At the time of transplant surgery, 56 of 100 patients had a CIED in situ. Hardware was retained postoperatively in 22 (39%), and the CIED had been in situ for 47 (interquartile range [IQR] 16-68) months for these cases, compared to 14 (IQR 3-24) months in those without. In two (9%) patients, the device generator was electively explanted during the week following OHT. There were no subsequent procedures undertaken to remove retained lead fragments. One (4%) had lead fragment embolization, one (4%) had endoluminal fragment migration, and one (4%) had lead fragment erosion into the mediastinum; all were asymptomatic and without adverse clinical sequelae. There was no infection associated with this hardware. The presence of retained lead fragments was not associated with additional mortality. Retained lead fragments following OHT occur commonly, without adverse clinical events for this cohort; however, the long-term clinical implications remain uncertain. Complete removal of all CIED hardware should be attempted at the time of OHT, and when this is not possible leads should be left in a state that facilitates their removal at a later date if required.
    Pacing and Clinical Electrophysiology 01/2014; · 1.75 Impact Factor
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    ABSTRACT: Broncho-pleural fistulae (BPF) are recognised as a rare complication following pneumonectomy. We describe a patient, who after failing conservative treatment, underwent closure of a persistent fistula with an atrial septal defect (ASD) occluder. Additionally we review the literature regarding management of BPF and the emerging role of cardiac defect closure devices as a possible treatment option.
    Heart Lung &amp Circulation 11/2013; · 1.25 Impact Factor
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    ABSTRACT: Demand for aortic valve intervention remains high, and together with the recent introduction of transcatheter aortic valve implantation, this motivates a review of surgical aortic valve replacement in elderly recipients.
    Asian cardiovascular & thoracic annals 10/2013; 22(5):526-533.
  • The Journal of heart and lung transplantation: the official publication of the International Society for Heart Transplantation 10/2013; · 3.54 Impact Factor
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    ABSTRACT: Trans-catheter aortic valve implantation (TAVI) became available at Auckland City Hospital in 2011 for patients with severe aortic stenosis in whom surgical aortic valve replacement (AVR) was deemed at high risk. We assessed whether introduction of TAVI affected the characteristics and outcomes of octogenarians undergoing AVR. Isolated AVR performed in patients ≥80 years of age during 2008-2012 were divided into two groups, pre- and post-TAVI introduction, for analyses. Isolated AVR was undertaken in 35 and 33 octogenarians pre- and post-TAVI introduction. The post-TAVI group were older (84.2 vs 82.3 years, P=0.003), had lower ejection fraction (P=0.026), more had inpatient surgery (76% vs 29%, P<0.001), with higher EuroSCORE II (5.4 vs 3.9%, P=0.033). Operative mortality was 0.0% in both groups. One-year survival was similar (97.6% vs 94.3%, P=0.613), but composite morbidity was lower in the post-TAVI group (9.1% vs 31.4%, P=0.035). Chronic respiratory disease (P=0.043) independently predicted mortality during follow-up, while number of coronary vessel>50% stenosis (P=0.050), creatinine clearance (P=0.016) and being in the pre-TAVI era group (P=0.022) predicted composite morbidity. Since TAVI was introduced, mean age and risk scores significantly increased in octogenarians undergoing AVR, while mortality rates remained similar and composite morbidity decreased.
    Heart Lung &amp Circulation 10/2013; · 1.25 Impact Factor
  • Jonathon M White, Andrew G Veale, Peter N Ruygrok
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    ABSTRACT: Obstructive sleep apnea (OSA) and patent foramen ovale (PFO) are common conditions and may coexist. In patients with OSA, increases in right-to-left shunting across a PFO may result in increased burden of hypoxia, although the effect of this is unknown. We report the cases of 3 patients with highly symptomatic OSA and PFO who underwent percutaneous closure with the Coherex FlatStent PFO Closure System. Although PFO closure can be achieved with minimally invasive techniques and low rates of adverse events, its importance in reducing hypoxia in this population is unknown. PFO closure may result in improvement in apneas and symptoms in selected OSA patients and may impact cardiovascular events in this group through hypoxia-mediated or other unrecognized mechanisms.
    The Journal of invasive cardiology 08/2013; 25(8):E169-71. · 1.57 Impact Factor
  • Heart Lung &amp Circulation 07/2013; 22(7):564–565. · 1.25 Impact Factor

Publication Stats

2k Citations
685.44 Total Impact Points

Institutions

  • 2006–2014
    • Auckland District Health Board
      • Green Lane Cardiovascular Service
      Окленд, Auckland, New Zealand
  • 2003–2013
    • Auckland City Hospital
      Окленд, Auckland, New Zealand
  • 2010
    • Erasmus MC
      • Department of Cardiology
      Rotterdam, South Holland, Netherlands
  • 2007–2008
    • Alfred Hospital
      Melbourne, Victoria, Australia
  • 2004
    • University of Auckland
      • Department of Medicine
      Окленд, Auckland, New Zealand
  • 2001
    • Monash University (Australia)
      Melbourne, Victoria, Australia
    • Mercy Angiography
      Окленд, Auckland, New Zealand
  • 1994–1996
    • Erasmus Universiteit Rotterdam
      • Department of Cardiology
      Rotterdam, South Holland, Netherlands