Estimation of intracardiac shunts in young children with a novel indicator dilution technology

Figures

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  Figure 1. Comparison between COstatus and transesophageal echocardiography for detecting and excluding a left-to-right shunt and an ROC curve showing accuracy for diagnosing a left-to-right shunt.

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  Figure 2. Comparison between categorized groups of Qp/Qs ratios of COstatus and Qp/Qs ratios estimated by perivascular flow probes around the pulmonary truncus and aorta (A) and Qp/Qs ratios calculated by the oximetric shunt equation from blood gas analysis. (B) The vertical bars contain 95% confidence intervals in each categorized shunt group (*indicates P < 0.05).

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  Figure 3. (A) Schematic picture of COstatus monitor and AV loop setup connected to a patient, (B) placement of venous ultrasound probe on AV loop, (C) injection of saline bolus into the AV loop, and (D) arterial dilution curve screen display showing a possible shunt.

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  Figure 4. The effect of a left-to-right intracardiac shunt observed in the arterial curve. One part of the injected indicator (saline) passes normally through the cardiopulmonary system and exits into the aorta. The second part recirculates multiple times through the pulmonary system (gray area) until all indicators exit the heart. This delay is observed in the descending part of the arterial dilution curve. (A) Normal dilution curve without intracardiac shunt, (B) Small intracardiac left-to right shunt, (C) Moderate intracardiac left-to-right shunt and (D) Large left-to-right intracardiac shunt. By analyzing the distance between an imaginary vertical line from peak dilution and the ascending dilution curve (a) and the descending dilution curve (b) at the half peak level, an asymmetry can be detected indicating the presence of a possible left-to-right shunt. (Pictures are adapted from the Shunts Modeling program, Transonic Systems Inc.).

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  Figure 5. Optima dual channel Flow-Qc meter, model HT364 and a schematic explanation of how the invasive COnfidence ultrasound flow probes were used to compare differences in blood flow in both pulmonary truncus (Qp) and ascending aorta (Qs) to estimate the shunt ratio (Qp/Qs). (A) Exposure of the heart through an open sternotomy, (B) placement of flow probe on the great arteries for blood flow measurements, and (C) in-theatre setup for the diagnostic AureFlow monitor and Optima flow meter. (Photos of flow probes and flow meter adapted with permission of Transonic Systems Inc.).