Wil Harrison

Middlemore Hospital, Окленд, Auckland, New Zealand

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Publications (6)10.89 Total impact

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    ABSTRACT: Background Disparities in health care access and outcomes between Maori (M) and Non-Maori (NM) New Zealanders have been reported but little is known about access to and outcomes following heart transplantation (HT). Methods A retrospective analysis was performed of M and NM who underwent HT in New Zealand. Demographic, clinical and outcome data were collected. Results Of 253 patients transplanted, 176 were European, 47 M (19%) and 30 of other ethnicities. M and NM groups were compared. Median age (both 46 years), gender (17% vs 21% female), waiting time (90 vs 76 days) and diagnosis (dilated cardiomyopathy–62% vs 58%) were similar for both groups. M were heavier (81 vs 71 kg, p < 0.0001) and more were blood group A (58% vs 38%). Five year survival was similar (79% vs 78%) but 10 year survival was significantly reduced in M (54% vs 67% p = 0.02). Conclusion The proportion of Maori who have undergone heart transplantation in New Zealand compares favourably with their proportion in the New Zealand population. The reasons for the adverse diverging outcomes after five years require further investigation.
    Heart Lung &amp Circulation 01/2013; · 1.25 Impact Factor
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    ABSTRACT: Central arterial pressure is a better predictor of adverse cardiovascular outcomes than brachial blood pressure, but noninvasive measurement by applanation tonometry is technically demanding. Pulsecor R6.5 is a novel device adapted from a standard sphygmomanometer which estimates the central aortic pressure from analysis of low-frequency suprasystolic waveforms at the occluded brachial artery. A physics-based model, which simulates the arterial system using elastic, thin-walled tube elements and Navier-Stokes equations, is used to calculate arterial pressure and flow propagation. To determine the reliability of the device, we compared 94 central systolic pressures estimated by Pulsecor to the simultaneous directly measured central aortic pressures at the time of coronary angiography in 37 individuals. There was good correlation in central SBP between catheter measurements and Pulsecor estimates by either invasive or noninvasive calibration methods (r = 0.99, P < 0.0001 and r = 0.95, P < 0.0001, respectively). The mean difference in central systolic pressure was 2.78 (SD 3.90) mmHg and coefficient of variation was 0.03 when the invasive calibration method was used.When the noninvasive calibration method was used, the mean difference in central systolic pressure was 0.25 (SD 6.31) mmHg and coefficient of variation was 0.05. We concluded that Pulsecor R6.5 provides a simple and easy method to noninvasively estimate central SBP, which has highly acceptable accuracy.
    Journal of Hypertension 07/2012; 30(9):1743-50. · 4.22 Impact Factor
  • Wil Harrison, Cindy Grines
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    ABSTRACT: (J Interven Cardiol 2011;24:413–415)
    Journal of Interventional Cardiology 09/2011; 24(5):413-5. · 1.50 Impact Factor
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    ABSTRACT: Elevated central arterial (aortic) blood pressure is related to increased risk of cardiovascular disease. Methods of non-invasively estimating this pressure would therefore be helpful in clinical practice. To achieve this goal, a physics-based model is derived to correlate the arterial pressure under a suprasystolic upper-arm cuff to the aortic pressure. The model assumptions are particularly applicable to the measurement method and result in a time-domain relation with two parameters, namely, the wave propagation transit time and the reflection coefficient at the cuff. Central pressures estimated by the model were derived from completely automatic, non-invasive measurement of brachial blood pressure and suprasystolic waveform and were compared to simultaneous invasive catheter measurements in 16 subjects. Systolic blood pressure agreement, mean (standard deviation) of difference was -1 (7)mmHg. Diastolic blood pressure agreement was 4 (4)mmHg. Correlation between estimated and actual central waveforms was greater than 90%. Individualization of model parameters did not significantly improve systolic and diastolic pressure agreement, but increased waveform correlation. Further research is necessary to confirm that more accurate brachial pressure measurement improves central pressure estimation.
    Journal of biomechanics 09/2009; 42(13):2111-5. · 2.66 Impact Factor
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    ABSTRACT: Left ventricular (LV) false aneurysm is an uncommon complication of myocardial infarction. Conventional treatment mandates surgical repair but is associated with significant perioperative risk. We present a case of successful percutaneous closure of a LV false aneurysm in a patient at high operative risk who suffered cardioembolic stroke related to thrombus within the aneurysm. The primary aim of treatment was to prevent recurrent embolic event.
    Heart Lung &amp Circulation 07/2008; 17(3):250-3. · 1.25 Impact Factor
  • Heart Lung and Circulation - HEART LUNG CIRC. 01/2008; 17.