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[Importance of sequential atrioventricular pacing in obstructive myocardiopathy with atrioventricular block]
Insights
Atrioventricular block (AVB) in hypertrophic obstructive cardiomyopathy worsens intraventricular pressure gradients. Sequential atrioventricular pacing effectively manages this complication by restoring atrial contribution to ventricular filling.
Area of Science:
- Cardiology
- Cardiac Electrophysiology
- Cardiovascular Medicine
Background:
- Hypertrophic obstructive cardiomyopathy (HOCM) is a complex condition often associated with dynamic intraventricular pressure gradients.
- Atrioventricular block (AVB) is a potential complication that can significantly alter cardiac hemodynamics.
Observation:
- A case study details a patient with HOCM experiencing worsening intraventricular pressure gradients upon the development of 2nd-degree AVB.
- The increased gradient was linked to diastolic lengthening, reduced aortic diastolic pressure, and diminished ventricular volume due to loss of atrial systole in complete AVB.
Findings:
- Second-degree AVB increased the intraventricular pressure gradient from 36 to 128 mmHg.
- Complete AVB led to a 33 mmHg gradient, which resolved with restored atrial systole via spontaneous or paced atrial contraction.
- Sequential atrioventricular pacing normalized the pressure gradient by ensuring proper atrial-ventricular synchrony.
Implications:
- This case highlights the critical role of atrial-ventricular synchrony in managing HOCM with AVB.
- Sequential atrioventricular pacing emerges as a potentially optimal pacing strategy for HOCM patients with complete AVB.
- Understanding these hemodynamic interactions is crucial for guiding therapeutic interventions in complex cardiac conditions.
Abstract:
A case of atrioventricular block (AVB) complicating hypertrophic obstructive cardiomyopathy is reported and analysed with respect to the results of cardiac catheterisation. The installation of 2nd degree AVB was associated with an increase of the intraventricular pressure gradient from 36 to 128 mmHg. This aggravation was related to the lenghtening of diastole which lowered the aortic diastolic pressure and allowed a more forceful ventricular contraction with a reduction in the calibre of the intraventricular stenosis. The sudden lenghtening of diastole also led to an increased contractility of the following systole. In complete AVB the increased gradient was related to a reduction in ventricular volume secondary to the loss of atrial systole. The 33 mmHg pressure gradient disappeared when spontaneous atrial systole or an atrial systole provoked by sequential atrioventricular pacing preceded ventricular contraction. Sequential atrioventricular pacing would seem to be the most appropriate pacing technique in hypertrophic obstructive cardiomyopathy complicated by complete AVB.