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Pulmonary arterial hypertension (PAH) is a complex disease involving increased resistance in the pulmonary arteries and subsequent right ventricular (RV) remodeling. Ventricular-arterial interactions are fundamental to PAH pathophysiology but are rarely captured in computational models. It is important to identify metrics that capture and quantify these interactions to inform our understanding of this disease as well as potentially facilitate patient stratification. Towards this end, we developed and calibrated two multi-scale high-resolution closed-loop computational models using open-source software: a high-resolution arterial model implemented using CRIMSON, and a high-resolution ventricular model implemented using FEniCS. Models were constructed with clinical data including non-invasive imaging and invasive hemodynamic measurements from a cohort of pediatric PAH patients. A contribution of this work is the discussion of inconsistencies in anatomical and hemodynamic data routinely acquired in PAH patients. We proposed and implemented strategies to mitigate these inconsistencies, and subsequently use this data to inform and calibrate computational models of the ventricles and large arteries. Computational models based on adjusted clinical data were calibrated until the simulated results for the high-resolution arterial models matched within 10% of adjusted data consisting of pressure and flow, whereas the high-resolution ventricular models were calibrated until simulation results matched adjusted data of volume and pressure waveforms within 10%. A statistical analysis was performed to correlate numerous data-derived and model-derived metrics with clinically assessed disease severity. Several model-derived metrics were strongly correlated with clinically assessed disease severity, suggesting that computational models may aid in assessing PAH severity. [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ahj.2007.02.019 Byline: Mark A. Law (a), Ronald G. Grifka (b), Charles E. Mullins (a), Michael R. Nihill (a) Abstract: Atrial septostomy is a palliative treatment for patients with pulmonary hypertension (PHTN) refractory to vasodilator therapy. Limited data exist in the pediatric population and in patients with repaired congenital heart defects. Author Affiliation: (a) Section of Cardiology, Department of Pediatrics, Baylor College of Medicine, Texas Children's Hospital, MC 19345-C, Houston, TX (b) Section of Cardiology, Department of Pediatrics, DeVos Children's Hospital, Grand Rapids, MI Article History: Received 10 November 2006; Accepted 16 February 2007

Children with hypoplastic left heart syndrome (HLHS) must undergo multiple surgical stages to reconstruct the anatomy to a sustainable single ventricle system. Stage I palliation, or the Norwood procedure, provides circulation to both pulmonary and systemic vasculature. The aorta is reconstructed and attached to the right ventricle and a fraction of systemic flow is redirected to the pulmonary arteries (PAs) through a systemic-to-PA shunt. Despite abundant hemodynamic data available 4–5 months after Norwood palliation, data is very scarce immediately following stage I. This data is critical in determining post-operative success. In this work, we combined population data and computational fluid dynamics (CFD) to characterize hemodynamics immediately following stage I (post-stage I) and prior to stage II palliation (pre-stage II). A patient-specific model was constructed as a baseline geometry, which was then scaled to reflect population-based morphological data at both time-points. Population-based hemodynamic data was then used to calibrate each model to reproduce blood flow representative of HLHS patients. The post-stage I simulation produced a PA pressure of 22 mmHg and high-frequency oscillations within the flow field indicating highly disturbed hemodynamics. Despite PA mean pressure dropping to 14 mmHg, the pre-stage II model also produced high-frequency flow components and PA wall shear stress increases. These suboptimal conditions may be necessary to ensure adequate PA flow throughout the pre-stage II period, as the shunt becomes relatively smaller compared to the patient's somatic growth. In the future, CFD can be used to optimize shunt design and minimize these suboptimal conditions. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the feasibility of stent dilation of venous obstructions/occlusions to permit transvenous pacing lead implantation. Innominate vein or superior vena cava (SVC) obstruction may preclude the implantation of transvenous pacing leads. Patients with d-transposition of the great arteries, after a Mustard or Senning procedure, and children with previously placed transvenous pacing leads are at higher risk for this vascular complication. From May 1993 to January 1996, eight pediatric patients who underwent transvenous pacing lead implantation or replacement were found to have significant innominate vein or SVC obstruction or occlusion. Utilizing intravascular stents, a combined interventional and electrophysiological approach was used to relieve the venous obstruction and to permit implantation of a new transvenous pacing lead. Two patients had complete SVC occlusion requiring puncture through the obstruction with a transseptal needle. Vessel recanalization was achieved with balloon dilation and stent implantation. The remaining six patients had severe venous obstruction with a mean minimum diameter of 3.1 ± 3.3 mm. The mean pressure gradient across the obstructed veins was 8.6 ± 7.3 mmHg. Following implantation of 15 Palmaz P308 stents in eight vessels, the mean diameter increased to 14.2 ± 1.9 mm and the mean pressure gradient across the stented vessels decreased to 1.0 ± 2.0 mmHg. A transvenous pacing lead was implanted successfully through the stent(s) immediately or 6–8 weeks later. Innominate vein and SVC obstruction can be safely and effectively relieved with intravascular stents and permit immediate or subsequent transvenous pacing lead implantation. [ABSTRACT FROM AUTHOR]

Focuses on the first implantation of Gianturco-Grifka Vascular Occlusion Device in a child as definitive treatment for a patent ductus arteriosus. Method of implantation; Performance of catheterization using intravenous sedation.