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Monitoring of heart failure: comparison of left atrial pressure with intrathoracic impedance and natriuretic peptide measurements in an experimental model of ovine heart failure.

Rademaker MT, Charles CJ, Melton IC, Richards AM, Frampton CM, Siou J, Qu F, Eigler NL, Gutfinger D, Troughton RW - Clin. Sci. (2011)

Bottom Line: In summary, impedance measured with an LV lead correlates significantly with changes in LAP, but exhibits a delayed response to acute alterations.Direct LAP, impedance and natriuretic peptide measurements all show promise as early indicators of worsening HF.ALAP provides an estimate of LAP that may be clinically useful.

View Article: PubMed Central - PubMed

Affiliation: Christchurch Cardioendocrine Research Group, University of Otago, Christchurch, New Zealand. miriam.rademaker@otago.ac.nz

ABSTRACT
Monitoring of HF (heart failure) with intracardiac pressure, intrathoracic impedance and/or natriuretic peptide levels has been advocated. We aimed to investigate possible differences in the response patterns of each of these monitoring modalities during HF decompensation that may have an impact on the potential for early therapeutic intervention. Six sheep were implanted with a LAP (left atrial pressure) sensor and a CRT-D (cardiac resynchronization therapy defibrillator) capable of monitoring impedance along six lead configuration vectors. An estimate of ALAP (LAP from admittance) was determined by linear regression. HF was induced by rapid ventricular pacing at 180 and 220 bpm (beats/min) for a week each, followed by a third week with daily pacing suspensions for increasing durations (1-5 h). Incremental pacing induced progressively severe HF reflected in increases in LAP (5.9 ± 0.4 to 24.5 ± 1.6 mmHg) and plasma atrial (20 ± 3 to 197 ± 36 pmol/l) and B-type natriuretic peptide (3.7 ± 0.7 to 32.7 ± 5.4 pmol/l) (all P<0.001) levels. All impedance vectors decreased in proportion to HF severity (all P<0.001), with the LVring (left ventricular)-case vector correlating best with LAP (r2=0.63, P<0.001). Natriuretic peptides closely paralleled rapid acute changes in LAP during alterations in pacing (P<0.001), whereas impedance changes were delayed relative to LAP. ALAP exhibited good agreement with LAP. In summary, impedance measured with an LV lead correlates significantly with changes in LAP, but exhibits a delayed response to acute alterations. Natriuretic peptides respond rapidly to acute LAP changes. Direct LAP, impedance and natriuretic peptide measurements all show promise as early indicators of worsening HF. ALAP provides an estimate of LAP that may be clinically useful.

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Related in: MedlinePlus

LAP, natriuretic peptide and LVring-case and RVcoil-case admittance vector responses in six sheep during acute and chronic changes in pacingValues shown are means ± S.E.M.
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Figure 1: LAP, natriuretic peptide and LVring-case and RVcoil-case admittance vector responses in six sheep during acute and chronic changes in pacingValues shown are means ± S.E.M.

Mentions: Incremental pacing induced progressively severe HF as indicated by rises in LAP from a prepacing baseline of 5.9 ± 0.4 to 15.3 ± 1.0 mmHg following a week of pacing at 180 bpm (P<0.001) and to 24.5 ± 1.6 mmHg after a second week pacing at 220 bpm (P<0.001) (Figure 1). LAP levels did not increase further during the third week when pacing at 220 bpm was suspended daily for 1–5 h. Figure 2 shows representative LAP waveform data from one sheep with corresponding electrograms during the various periods of the study protocol. Part of the mechanism for producing an elevation in LAP during rapid ventricular pacing appears to be cannon A-waves that represent a simultaneous atrial and ventricular contraction. An acute change in LAP from 24.7 to 14.5 mmHg following cessation of pacing during the third week of pacing (days 14–18) with the disappearance of cannon A-waves occurring within 3 min of pacing discontinuation is shown (Figures 2C and 2D). The permanent termination of pacing (day 21) resulted in the gradual reduction of LAP to pre-pacing baseline levels over the subsequent 4 days (Figure 1).


Monitoring of heart failure: comparison of left atrial pressure with intrathoracic impedance and natriuretic peptide measurements in an experimental model of ovine heart failure.

Rademaker MT, Charles CJ, Melton IC, Richards AM, Frampton CM, Siou J, Qu F, Eigler NL, Gutfinger D, Troughton RW - Clin. Sci. (2011)

LAP, natriuretic peptide and LVring-case and RVcoil-case admittance vector responses in six sheep during acute and chronic changes in pacingValues shown are means ± S.E.M.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2990201&req=5

Figure 1: LAP, natriuretic peptide and LVring-case and RVcoil-case admittance vector responses in six sheep during acute and chronic changes in pacingValues shown are means ± S.E.M.
Mentions: Incremental pacing induced progressively severe HF as indicated by rises in LAP from a prepacing baseline of 5.9 ± 0.4 to 15.3 ± 1.0 mmHg following a week of pacing at 180 bpm (P<0.001) and to 24.5 ± 1.6 mmHg after a second week pacing at 220 bpm (P<0.001) (Figure 1). LAP levels did not increase further during the third week when pacing at 220 bpm was suspended daily for 1–5 h. Figure 2 shows representative LAP waveform data from one sheep with corresponding electrograms during the various periods of the study protocol. Part of the mechanism for producing an elevation in LAP during rapid ventricular pacing appears to be cannon A-waves that represent a simultaneous atrial and ventricular contraction. An acute change in LAP from 24.7 to 14.5 mmHg following cessation of pacing during the third week of pacing (days 14–18) with the disappearance of cannon A-waves occurring within 3 min of pacing discontinuation is shown (Figures 2C and 2D). The permanent termination of pacing (day 21) resulted in the gradual reduction of LAP to pre-pacing baseline levels over the subsequent 4 days (Figure 1).

Bottom Line: In summary, impedance measured with an LV lead correlates significantly with changes in LAP, but exhibits a delayed response to acute alterations.Direct LAP, impedance and natriuretic peptide measurements all show promise as early indicators of worsening HF.ALAP provides an estimate of LAP that may be clinically useful.

View Article: PubMed Central - PubMed

Affiliation: Christchurch Cardioendocrine Research Group, University of Otago, Christchurch, New Zealand. miriam.rademaker@otago.ac.nz

ABSTRACT
Monitoring of HF (heart failure) with intracardiac pressure, intrathoracic impedance and/or natriuretic peptide levels has been advocated. We aimed to investigate possible differences in the response patterns of each of these monitoring modalities during HF decompensation that may have an impact on the potential for early therapeutic intervention. Six sheep were implanted with a LAP (left atrial pressure) sensor and a CRT-D (cardiac resynchronization therapy defibrillator) capable of monitoring impedance along six lead configuration vectors. An estimate of ALAP (LAP from admittance) was determined by linear regression. HF was induced by rapid ventricular pacing at 180 and 220 bpm (beats/min) for a week each, followed by a third week with daily pacing suspensions for increasing durations (1-5 h). Incremental pacing induced progressively severe HF reflected in increases in LAP (5.9 ± 0.4 to 24.5 ± 1.6 mmHg) and plasma atrial (20 ± 3 to 197 ± 36 pmol/l) and B-type natriuretic peptide (3.7 ± 0.7 to 32.7 ± 5.4 pmol/l) (all P<0.001) levels. All impedance vectors decreased in proportion to HF severity (all P<0.001), with the LVring (left ventricular)-case vector correlating best with LAP (r2=0.63, P<0.001). Natriuretic peptides closely paralleled rapid acute changes in LAP during alterations in pacing (P<0.001), whereas impedance changes were delayed relative to LAP. ALAP exhibited good agreement with LAP. In summary, impedance measured with an LV lead correlates significantly with changes in LAP, but exhibits a delayed response to acute alterations. Natriuretic peptides respond rapidly to acute LAP changes. Direct LAP, impedance and natriuretic peptide measurements all show promise as early indicators of worsening HF. ALAP provides an estimate of LAP that may be clinically useful.

Show MeSH
Related in: MedlinePlus