Left bundle branch block increases left ventricular diastolic pressure during tachycardia due to incomplete relaxation
| Autor: | Hans Henrik Odland, Petter Storsten, Espen W. Remme, John M Aalen, Otto A. Smiseth, Magnus Reinsfelt Krogh, O S Andersen, C K Larsen, Helge Skulstad, Espen Boe |
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| Rok vydání: | 2020 |
| Předmět: |
0301 basic medicine
Tachycardia medicine.medical_specialty Materials science Physiology medicine.medical_treatment Bundle-Branch Block Cardiac resynchronization therapy Blood Pressure 030204 cardiovascular system & hematology Ventricular Function Left Cardiac Resynchronization Therapy Electrocardiography 03 medical and health sciences Dogs 0302 clinical medicine Diastole Physiology (medical) Internal medicine Electrical conduction medicine Animals cardiovascular diseases Left bundle branch block medicine.disease 030104 developmental biology Blood pressure Heart failure Cardiology cardiovascular system Relaxation (physics) medicine.symptom |
| ISSN: | 8750-7587 |
| Popis: | We investigated whether tachycardia in left bundle branch block (LBBB) decreases left ventricular (LV) diastolic distensibility and increases diastolic pressures due to incomplete relaxation, and if cardiac resynchronization therapy (CRT) modifies this response. Thirteen canines were studied at baseline heart rate (120 beats/min) and atrial paced tachycardia (180 beats/min) before and after induction of LBBB and during CRT. LV and left atrial pressures (LAP) were measured by micromanometers and dimensions by sonomicrometry. The time constant τ of exponential pressure decay and degree of incomplete relaxation at mitral valve opening (MVO) and end diastole (ED) based on extrapolation of the exponential decay were assessed. Changes in LV diastolic distensibility were investigated using the LV transmural pressure-volume (PV) relation. LBBB caused prolongation of τ ( P < 0.03) and increased the degree of incomplete relaxation during tachycardia at MVO ( P < 0.001) and ED ( P = 0.08) compared with normal electrical activation. This was associated with decreased diastolic distensibility seen as upward shift of the PV relation at MVO by 18.4 ± 7.0 versus 12.0 ± 5.0 mmHg, at ED by 9.8 ± 2.3 versus 4.7 ± 2.3 mmHg, and increased mean LAP to 11.4 ± 2.7 versus 8.5 ± 2.6 mmHg, all P < 0.006. CRT shifted the LV diastolic PV relation downwards during tachycardia, reducing LAP and LV diastolic pressures ( P < 0.03). Tachycardia in LBBB reduced LV diastolic distensibility and increased LV diastolic pressures due to incomplete relaxation, whereas CRT normalized these effects. Clinical studies are needed to determine whether a similar mechanism contributes to dyspnea and exercise intolerance in LBBB and if effects of CRT are heart rate dependent. NEW & NOTEWORTHY Compared with normal electrical conduction, tachycardia in left bundle branch block resulted in incomplete relaxation during filling, particularly of the late activated left ventricular lateral wall. This further resulted in reduced left ventricular diastolic distensibility and elevated diastolic pressures and thus amplified the benefits of cardiac resynchronization therapy in this setting. |
| Databáze: | OpenAIRE |
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