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Hemodynamic Surveillance of Ventricular Pacing Effectiveness with the Transvalvular Impedance Sensor.

Calvi V, Pizzimenti G, Lisi M, Doria G, Vasquez L, Lisi F, Felis S, Tempio D, Virgilio A, Barbetta A, Di Gregorio F - Adv Med (2014)

Bottom Line: When the energy scan resulted in capture loss, the TVI system must detect the failure and increase the output voltage.The procedure was never interrupted by the physician, as the automatic energy regulation ensured full patient's safety.The median prevalence of false alarms was 0.336%.

View Article: PubMed Central - PubMed

Affiliation: Arrhythmology OU, Ferrarotto Hospital, University of Catania, Catania, Italy.

ABSTRACT
The Transvalvular Impedance (TVI) is derived between atrial and ventricular pacing electrodes. A sharp TVI increase in systole is an ejection marker, allowing the hemodynamic surveillance of ventricular stimulation effectiveness in pacemaker patients. At routine follow-up checks, the ventricular threshold test was managed by the stimulator with the supervision of a physician, who monitored the surface ECG. When the energy scan resulted in capture loss, the TVI system must detect the failure and increase the output voltage. A TVI signal suitable to this purpose was present in 85% of the tested patients. A total of 230 capture failures, induced in 115 patients in both supine and sitting upright positions, were all promptly recognized by real-time TVI analysis (100% sensitivity). The procedure was never interrupted by the physician, as the automatic energy regulation ensured full patient's safety. The pulse energy was then set at 4 times the threshold to test the alarm specificity during daily activity (sitting, standing up, and walking). The median prevalence of false alarms was 0.336%. The study shows that TVI-based ejection assessment is a valuable approach to the verification of pacing reliability and the autoregulation of ventricular stimulation energy.

No MeSH data available.


Related in: MedlinePlus

Real-time telemetry of event markers (1st tracing) and transvalvalvular impedance (2nd tracing) with simultaneous surface ECG recording (I, II, and aVR from the 3rd to bottom tracings, all with the same voltage scale) during ventricular threshold analysis in VDD. On the markers tracing, short bars represent atrial sensing, intermediate bars ventricular pacing, and the longest bars ventricular sensing in the pacemaker refractory period. From the 5th pulse onward the stimulation was below threshold and a narrow QRS replaced the pacing-evoked wide complex. Nevertheless, a properly timed TVI fluctuation was present, confirming the ejection occurrence, and the energy scan continued down to the minimum pulse amplitude available.
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fig3: Real-time telemetry of event markers (1st tracing) and transvalvalvular impedance (2nd tracing) with simultaneous surface ECG recording (I, II, and aVR from the 3rd to bottom tracings, all with the same voltage scale) during ventricular threshold analysis in VDD. On the markers tracing, short bars represent atrial sensing, intermediate bars ventricular pacing, and the longest bars ventricular sensing in the pacemaker refractory period. From the 5th pulse onward the stimulation was below threshold and a narrow QRS replaced the pacing-evoked wide complex. Nevertheless, a properly timed TVI fluctuation was present, confirming the ejection occurrence, and the energy scan continued down to the minimum pulse amplitude available.

Mentions: Although TVI proved very sensitive to the absence of mechanical activity following ventricular pacing, the system could not discriminate between different activation patterns. Therefore, the only feature suitable to distinguish intrinsic and evoked ventricular contraction was the time-relationship with the pacing spike. In few cases where the TVI signal was so deteriorated in VVI to be unacceptable to the control system, a threshold test was attempted in the presence of sequential pacing. Unless the intrinsic AV conduction was absent or very slow, a TVI fluctuation due to natural conduction was detected anyway within the expected systolic interval triggered by the pacing pulse, even with a short AV delay. As a result, properly timed ejection was confirmed by TVI and no capture-loss alarm was raised when the QRS shifted from an evoked wide complex to a narrow signal, indicating the occurrence of intrinsic conduction instead of effective stimulation. An example is provided in Figure 3.


Hemodynamic Surveillance of Ventricular Pacing Effectiveness with the Transvalvular Impedance Sensor.

Calvi V, Pizzimenti G, Lisi M, Doria G, Vasquez L, Lisi F, Felis S, Tempio D, Virgilio A, Barbetta A, Di Gregorio F - Adv Med (2014)

Real-time telemetry of event markers (1st tracing) and transvalvalvular impedance (2nd tracing) with simultaneous surface ECG recording (I, II, and aVR from the 3rd to bottom tracings, all with the same voltage scale) during ventricular threshold analysis in VDD. On the markers tracing, short bars represent atrial sensing, intermediate bars ventricular pacing, and the longest bars ventricular sensing in the pacemaker refractory period. From the 5th pulse onward the stimulation was below threshold and a narrow QRS replaced the pacing-evoked wide complex. Nevertheless, a properly timed TVI fluctuation was present, confirming the ejection occurrence, and the energy scan continued down to the minimum pulse amplitude available.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4590946&req=5

fig3: Real-time telemetry of event markers (1st tracing) and transvalvalvular impedance (2nd tracing) with simultaneous surface ECG recording (I, II, and aVR from the 3rd to bottom tracings, all with the same voltage scale) during ventricular threshold analysis in VDD. On the markers tracing, short bars represent atrial sensing, intermediate bars ventricular pacing, and the longest bars ventricular sensing in the pacemaker refractory period. From the 5th pulse onward the stimulation was below threshold and a narrow QRS replaced the pacing-evoked wide complex. Nevertheless, a properly timed TVI fluctuation was present, confirming the ejection occurrence, and the energy scan continued down to the minimum pulse amplitude available.
Mentions: Although TVI proved very sensitive to the absence of mechanical activity following ventricular pacing, the system could not discriminate between different activation patterns. Therefore, the only feature suitable to distinguish intrinsic and evoked ventricular contraction was the time-relationship with the pacing spike. In few cases where the TVI signal was so deteriorated in VVI to be unacceptable to the control system, a threshold test was attempted in the presence of sequential pacing. Unless the intrinsic AV conduction was absent or very slow, a TVI fluctuation due to natural conduction was detected anyway within the expected systolic interval triggered by the pacing pulse, even with a short AV delay. As a result, properly timed ejection was confirmed by TVI and no capture-loss alarm was raised when the QRS shifted from an evoked wide complex to a narrow signal, indicating the occurrence of intrinsic conduction instead of effective stimulation. An example is provided in Figure 3.

Bottom Line: When the energy scan resulted in capture loss, the TVI system must detect the failure and increase the output voltage.The procedure was never interrupted by the physician, as the automatic energy regulation ensured full patient's safety.The median prevalence of false alarms was 0.336%.

View Article: PubMed Central - PubMed

Affiliation: Arrhythmology OU, Ferrarotto Hospital, University of Catania, Catania, Italy.

ABSTRACT
The Transvalvular Impedance (TVI) is derived between atrial and ventricular pacing electrodes. A sharp TVI increase in systole is an ejection marker, allowing the hemodynamic surveillance of ventricular stimulation effectiveness in pacemaker patients. At routine follow-up checks, the ventricular threshold test was managed by the stimulator with the supervision of a physician, who monitored the surface ECG. When the energy scan resulted in capture loss, the TVI system must detect the failure and increase the output voltage. A TVI signal suitable to this purpose was present in 85% of the tested patients. A total of 230 capture failures, induced in 115 patients in both supine and sitting upright positions, were all promptly recognized by real-time TVI analysis (100% sensitivity). The procedure was never interrupted by the physician, as the automatic energy regulation ensured full patient's safety. The pulse energy was then set at 4 times the threshold to test the alarm specificity during daily activity (sitting, standing up, and walking). The median prevalence of false alarms was 0.336%. The study shows that TVI-based ejection assessment is a valuable approach to the verification of pacing reliability and the autoregulation of ventricular stimulation energy.

No MeSH data available.


Related in: MedlinePlus