Sarah A. Hope

Redefining Expectations of Long-Term Survival After the Fontan Procedure Twenty-Five Years of Follow-Up From the Entire Population of Australia and New Zealand

Background— The life expectancy of patients undergoing a Fontan procedure is unknown. Methods and Results— Follow-up of all 1006 survivors of the 1089 patients who underwent a Fontan procedure in Australia and New Zealand was obtained from a binational population-based registry including all pediatric and adult cardiac centers. There were 203 atriopulmonary connections (AP; 1975–1995), 271 lateral tunnels (1988–2006), and 532 extracardiac conduits (1997–2010). The proportion with hypoplastic left heart syndrome increased from 1/173 (1%) before 1990 to 80/500 (16%) after 2000. Survival at 10 years was 89% (84%–93%) for AP and 97% (95% confidence interval [CI], 94%–99%) for lateral tunnels and extracardiac conduits. The longest survival estimate was 76% (95% CI, 67%–82%) at 25 years for AP. AP independently predicted worse survival compared with extracardiac conduits (hazard ratio, 6.2; P<0.001; 95% CI, 2.4–16.0). Freedom from failure (death, transplantation, takedown, conversion to extracardiac conduits, New York Heart Association III/IV, or protein-losing enteropathy/plastic bronchitis) 20 years after Fontan was 70% (95% CI, 63%–76%). Hypoplastic left heart syndrome was the primary predictor of Fontan failure (hazard ratio, 3.8; P<0.001; 95% CI, 2.0–7.1). Ten-year freedom from failure was 79% (95% CI, 61%–89%) for hypoplastic left heart syndrome versus 92% (95% CI, 87%–95%) for other morphologies. Conclusions— The long-term survival of the Australia and New Zealand Fontan population is excellent. Patients with an AP Fontan experience survival of 76% at 25 years. Technical modifications have further improved survival. Patients with hypoplastic left heart syndrome are at higher risk of failure. Large, comprehensive registries such as this will further improve our understanding of late outcomes after the Fontan procedure.

Effect of non-invasive calibration of radial waveforms on error in transfer-function-derived central aortic waveform characteristics

Transfer function techniques are increasingly used for non-invasive estimation of central aortic waveform characteristics. Non-invasive radial waveforms must be calibrated for this purpose. Most validation studies have used invasive pressures for calibration, with little data on the impact of non-invasive calibration on transfer-function-derived aortic waveform characteristics. In the present study, simultaneous invasive central aortic (Millar Mikro-tip catheter transducer) and non-invasive radial (Millar Mikro-tip tonometer) pressure waveforms and non-invasive brachial pressures (Dinamap) were measured in 42 subjects. In this cohort, radial waveforms were calibrated to both invasive and non-invasive mean and diastolic pressures. From each of these, central waveforms were reconstructed using a generalized transfer function obtained by us from a previous cohort [Hope, Tay, Meredith and Cameron (2002) Am. J. Physiol. Heart Circ. Physiol. 283, H1150-H1156]. Waveforms were analysed for parameters of potential clinical interest. For calibrated radial and reconstructed central waveforms, different methods of calibration were associated with differences in pressure (P<0.001), but not time parameters or augmentation index. Whereas invasive calibration resulted in little error in transfer function estimation of central systolic pressure (difference -1+/-8 mmHg; P=not significant), non-invasive calibration resulted in significant underestimation (7+/-12 mmHg; P<0.001). Errors in estimated aortic parameters differed with non-invasively calibrated untransformed radial and transfer-function-derived aortic waveforms (all P<0.01), with smaller absolute errors with untransformed radial waveforms for most pressure parameters [systolic pressure, 5+/-16 and 7+/-12 mmHg; pulse pressure, 0+/-16 and 4+/-12 mmHg (radial and derived aortic respectively)]. When only non-invasive pressures are accessible, analysis of untransformed radial waveforms apparently produces smaller errors in the estimation of central aortic systolic pressure, and other waveform parameters, than using a generalized transfer function.

Drug effects on the mechanical properties of large arteries in humans

1 Arteries become stiffer with increasing age and various disease states. A complete description of arterial mechanical properties in vivo is not possible, although a number of methods have been used. 2 Detailed discussion in the present review is limited to pulse wave velocity and estimates of central waveform morphology derived by the application of a generalized arterial transfer function. 3 Many drugs affect these parameters, either increasing or decreasing apparent stiffness. However, the extent to which changes reflect changes in blood pressure rather than more fundamental vessel wall properties remains unclear. Similarly, it is as yet unknown whether determining the need for, or assessing the effectiveness of, drug treatment by the assessment of arterial mechanical properties will offer any advantage and the usefulness of these techniques as routine clinical tools remains to be established.

Reliability of transfer functions in determining central pulse pressure and augmentation index

We read with interest the study by Wilkinson et al. [(1)][1] in the March 20, 2002, issue of JACC . The investigators employed pulse wave analysis using sphygmorCor software (AtCor Medical, Sydney, Australia) for the derivation of central aortic waveforms from radial waveforms acquired by

Letter by Cameron et al Regarding Article, “Differential Impact of Blood Pressure-Lowering Drugs on Central Aortic Pressure and Clinical Outcomes: Principal Results of the Conduit Artery Function Evaluation (CAFE) Study”

To the Editor: We read with interest the report of the Conduit Artery Function Evaluation (CAFE) study1 showing a difference in SphygmoCor-derived central systolic blood pressure (SBP) between the 2 arms of an Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT) substudy (despite similar brachial blood pressure changes). We would make 3 points. First, the authors seem to have misinterpreted our work (authors’ Reference 53)2 as showing a “precision” of 1 mm Hg between calculated central aortic and directly measured SBP in the context of noninvasive studies. This figure relates to …

Is There Any Advantage to Using an Arterial Transfer Function

To the Editor: We read with interest the paper by Millasseau et al,1 which raises the question of whether the application of an arterial transfer function to noninvasively acquired radial artery pressure waveform data is necessary for the estimation of central aortic waveform characteristics. Although the conclusion that this approach offers no advantage over the simple analysis of untransformed radial artery pressure waveforms is valid, it should be remembered that the approach of these authors demonstrates only comparability and does not add to the debate as to whether arterial transfer function techniques enable accurate estimation of central aortic waveform parameters, because no directly measured central aortic waveforms were available for comparison. Our own findings, derived from noninvasive radial waveforms compared with directly measured central aortic waveforms, have demonstrated close relationships between several radial and measured central aortic waveform parameters proposed to be of potential clinical value, such as systolic and diastolic pressure time integrals.2,3 However, the radial artery augmentation index (AI) was unrelated to, or at best weakly correlated with, the …