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Left ventricular cavitary geometry and dynamic intracavitary left ventricular obstruction during dobutamine stress
Y Hashimoto1, C L Reid, J M Gardin
1Department of Medicine, University of California, Irvine, USA.
Insights
Dynamic left ventricular obstruction during dobutamine stress echocardiography is linked to a narrower left ventricular shape and increased contractility. This finding aids in understanding cardiac mechanics during stress tests.
Area of Science:
- Cardiology
- Echocardiography
- Physiology
Background:
- Dynamic intracavitary left ventricular obstruction is a recognized phenomenon during dobutamine stress echocardiography.
- Understanding the geometric and functional factors contributing to this obstruction is crucial for accurate diagnosis and patient management.
Purpose of the Study:
- To investigate the relationship between left ventricular cavity geometry and dynamic intracavitary left ventricular obstruction.
- To determine if specific baseline left ventricular dimensions predict the occurrence of obstruction during dobutamine stress.
Main Methods:
- 44 patients undergoing dobutamine stress echocardiography were evaluated.
- Left ventricular cavity geometry was assessed using the apical-to-mid-cavity dimension ratio (D1/D2).
- Left ventricular outflow tract Doppler velocity was measured at various stages of dobutamine infusion.
Main Results:
- Dynamic intracavitary left ventricular obstruction occurred in 23% of patients.
- Patients with obstruction had a significantly narrower left ventricular end-systolic dimension and a higher D1/D2 ratio at baseline.
- Higher D1/D2 ratio and increased left ventricular fractional shortening correlated with maximal outflow Doppler velocity.
Conclusions:
- Dynamic left ventricular intracavitary obstruction during dobutamine infusion is associated with a characteristic "narrower-waisted" left ventricular geometry.
- Increased left ventricular contractility is also linked to the development of this obstruction.
- These findings suggest that baseline ventricular shape and contractility are key determinants of dynamic obstruction during dobutamine stress.
Abstract:
To investigate the relationship between left ventricular cavity geometry and dynamic intracavitary left ventricular obstruction occurring during dobutamine stress echocardiography, we evaluated 44 patients who underwent dobutamine stress echocardiography. Dynamic intracavitary left ventricular obstruction appeared in 10 (23%) patients (Group 1), and was absent in the remaining 34 patients (Group 2), during dobutamine stress echocardiography. The ratio of the apicalto-narrowest mid-left ventricular minor-axis dimension (D1/D2), as an index of the left ventricular cavitary geometry, was measured in the baseline two dimensional apical long-axis view. The left ventricular out-flow blood Doppler velocity was measured in the apical long-axis or five-chamber view at each stage during dobutamine infusion. Left ventricular end-systolic dimension was smaller (21 +/- 4 mm v 29 +/- 6 mm; p< .01), percent fractional shortening of the left ventricle was greater (51 +/- 4% v 39 +/- 8%, P>.01), and D1/D2 was greater (1.13 +/- 0.08 v.0.96 +/- 0.09; p < .0001) in Group 1 than in Group 2 in the baseline echocardiogram. Maximal out flow blood Doppler velocity during dobutamine infusion correlated moderately with percent fractional shortening of the left ventricle (r = .53; P < .01) and D1/D2 (r = .60; P < .0001). Dynamic intracavitary left ventricular obstruction, defined as an elevated intracavitary Doppler flow velocity with late-systolic peaking, was not related to the presence of left ventricular hypertrophy or the development of hypotension during dobutamine infusion. We conclude that dynamic left ventricular intracavitary obstruction during dobutamine infusion is associated with a characteristic (narrower-waisted) left ventricular cavitary geometry and increased contractility.