Combined fluid-filled and micromanometer-tip catheter system for high-fidelity pressure recordings in infants
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A new catheter system combining a micromanometer-tip catheter with a pigtail catheter provides high-fidelity pressure recordings. This innovation enables accurate assessment of systolic and diastolic function in infants and young children.
Area of Science:
- Pediatric Cardiology
- Biomedical Engineering
- Hemodynamics
Background:
- Assessing systolic and diastolic function in pediatric patients is challenging due to difficulties in obtaining accurate pressure measurements.
- Existing fluid-filled systems lack adequate frequency response, while micromanometer-tip catheters are difficult to use in infants and young children.
Purpose of the Study:
- To evaluate a novel system combining a micromanometer-tip catheter with a standard pigtail catheter for high-fidelity pressure recordings in pediatric populations.
- To determine the frequency response of this combined system across various catheter sizes.
Main Methods:
- The frequency response of combined micromanometer-tip (Millar) and pigtail catheters was tested using 3.2 Fr, 4.0 Fr, and 5.0 Fr pigtail catheters of varying lengths.
- Frequency response was defined by measuring the system's performance up to its resonant frequency.
Main Results:
- The 3.2 Fr-40-cm system showed a flat response to 90 Hz (resonant frequency 130 Hz), suitable for heart rates up to 120 bpm.
- Longer 3.2 Fr catheters and all tested 4.0 Fr and 5.0 Fr catheters exhibited reduced frequency response.
- Increasing catheter diameter or length degraded the frequency response.
Conclusions:
- The combined micromanometer-tip and pigtail catheter system offers high-fidelity pressure tracings.
- This system is suitable for assessing pressure-derived indices of systolic and diastolic function in infants and young children.
- Careful selection of catheter size is crucial for optimal performance.
Abstract:
Investigation of pressure-derived indices of systolic and diastolic function in infants and young children has been limited, in part due to difficulty in obtaining high-fidelity pressure recordings. Standard fluid-filled catheter-manometer systems have a frequency response which is inadequate for this purpose, whereas high-frequency response micromanometer-tip catheters systems are difficult to use in this age group. Therefore, a system was investigated whereby a micromanometer-tip catheter (Millar) was connected directly to a standard pigtail catheter. The frequency response of this combined system was defined using 3.2 Fr pigtails of 40, 50, and 65 cm, 4.0 Fr pigtails of 50, 65, and 80 cm, and 5.0 Fr pigtails of 80 and 100 cm. In three different catheters of each diameter and length, minimal variation in response was seen. The 3.2 Fr-40-cm system demonstrated a flat line (100%) response to 90 Hz with a resonant frequency of 130 Hz. This is certainly adequate for determination of pressure derivatives for heart rates up to 120 beats per minute. The longer 3.2 Fr catheters demonstrated a poorer frequency response. The 4.0-Fr-50-cm system was flat line to 60 Hz, rising to 175% response at the resonant frequency of 85 Hz. This is adequate for determination of pressure derivatives at heart rates up to 120 beats per minute. Increasing the diameter or length of the pigtail catheter resulted in further deterioration of the frequency response. Thus, this system provides high-fidelity tracings suitable for assessment of pressure-derived indices of systolic and diastolic function in infants and young children.