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Impaired sinus node function and global atrial conduction time after high rate atrial pacing in dogs

100%

Zupan I., Kozelj M., Butinar J., Rakovec P.

Cellular and Molecular Biology Letters

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2002

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tom 07

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nr 2

In animal and human studies, it has been shown that atrial fibrillation shortens the atrial refractory period and impairs its rate adaptation. The objective of this study was to evaluate the effects of high-rate pacing on sinus node function and intra-atrial conduction. Eight dogs were subjected to rapid atrial pacing (AP) at 400 bpm for 16 days. Sinus node recovery time (SNRT) and P-wave duration were measured at baseline, immediately after AP and four weeks after the termination of AP. SNRT immediately after AP was significantly prolonged at all pacing rates compared to the baseline values. P-wave duration was significantly longer after AP relative to the baseline values. All the variables were completely reversible four weeks after the termination of pacing. Rapid AP induces sinus node dysfunction and prolongs the intra-atrial conduction time. It is possible that the electrical remodelling extends to the sinus node as well.

2

Ehocardiographic evaluation of regional left atrial function after rapid atrial pacing

88%

Kozelj M., Zupan I., Butinar J., Seliskar A., Rakovec P.

Cellular and Molecular Biology Letters

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2002

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tom 07

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nr 2

Rapid regular atrial pacing (RAP) produces changes in atrial function similar to those caused by atrial fibrillation in animal models. Left atrial appendage (LAA) function represents regional atrial function. The aim of our study was to investigate the inﬂuence of RAP on left atrial regional function and to evaluate the reversibility of changes after terminationtermination of pacing in a canine model. Eight dogs were subjected to RAP (400 bpm) for 16 days. Transesophageal echocardiography was performed at baseline, immediately after RAP and weeks after the terminationtermination of RAP. The LAA peak late emptying velocity (LAA-E) and filling wave (LAA-f) were measured. LAA-E velocities were significantly reduced and filling wave velocities (LAA-f) were significantly less negative after RAP compared with the baseline values. Four weeks after terminationtermination of pacing, the LAA-E and LAA-f velocities were normal. RAP results in impaired regional atrial systolic and diastolic function. The changes were completely reversible 4 weeks after terminationtermination of pacing. These results suggest that the LAA is mechanically stunned after RAP.

3

Nicardipine diminished equinatoxin II-induced decrease of coronary flow in isolated rat and pig hearts

76%

Bunc M., Rozman J., Vidmar A., Rakovec P., Drevensek G., Budihna M. V., Suput D.

Cellular and Molecular Biology Letters

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2002

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tom 07

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nr 2

Equinatoxin II (EqT II) is a basic, cardiotoxic polypeptide. The vasoconstrictory effect of the toxin on isolated porcine coronary arteries was diminished by nicardipine, an L-type calcium channel antagonist. A comparison was made of the effects of EqT II alone and EqT II in the presence of nicardipine on the coronary flow in porcine and rat hearts isolated according to Langendorff's method. In both models EqT II decreased coronary flow in a dose-dependent manner and there were no statistically significant differences between the two models (p>0.05). However, 1µM nicardipine diminished the effects of EqT II on coronary flow in isolated porcine hearts more than in isolated rat hearts (p<0.05). The results suggest that the activation of L-type calcium channels is one of the mechanisms involved in the lowering of coronary flow induced by EqT II.

Ograniczanie wyników

3 Cellular and Molecular Biology Letters

3 Rakovec P.

2 Butinar J.

2 Kozelj M.

2 Zupan I.

1 Budihna M. V.

1 Bunc M.

1 Drevensek G.

1 Rozman J.

1 Seliskar A.

1 Suput D.

1 Vidmar A.

3 2002

Impaired sinus node function and global atrial conduction time after high rate atrial pacing in dogs

Ehocardiographic evaluation of regional left atrial function after rapid atrial pacing

Nicardipine diminished equinatoxin II-induced decrease of coronary flow in isolated rat and pig hearts