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Fixed left ventricular outflow tract obstruction in presumed hypertrophic obstructive cardiomyopathy: implications
C J Bruce1, R A Nishimura, A J Tajik
1Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic and Mayo Foundation, Rochester, Minnesota 55905, USA.
Insights
Not all hypertrophic obstructive cardiomyopathy (HOCM) patients have dynamic obstruction. Some have fixed left ventricular outflow tract (LVOT) obstruction, requiring specific surgical intervention for gradient relief.
Area of Science:
- Cardiology
- Cardiac Surgery
- Diagnostic Imaging
Background:
- Hypertrophic obstructive cardiomyopathy (HOCM) is often associated with dynamic left ventricular outflow tract (LVOT) obstruction.
- However, a subset of patients may present with fixed LVOT obstruction, necessitating accurate diagnosis for appropriate therapeutic strategies.
Observation:
- This study reviewed 4 patients with presumed HOCM who exhibited fixed LVOT obstruction.
- Echocardiographic findings included early-peaking LVOT Doppler signals or absence of systolic anterior motion of the mitral valve.
Findings:
- The causes of fixed LVOT obstruction identified were accessory mitral tissue, subaortic tunnel stenosis, and a subaortic ridge.
- Surgical relief of the fixed obstruction in all 4 patients successfully eliminated the ventricular outflow tract gradient.
Implications:
- The findings highlight that not all patients with presumed HOCM have dynamic obstruction; some have fixed LVOT obstruction.
- Accurate identification of fixed LVOT obstruction through comprehensive echocardiography is crucial for surgical management.
- Surgical intervention can effectively resolve the outflow tract gradient in these specific cases.
Background:
A subset of patients presenting with a presumed diagnosis of hypertrophic obstructive cardiomyopathy (HOCM) have a fixed left ventricular outflow tract (LVOT) obstruction. Recognition of this pathophysiologic abnormality is important in choosing therapy.
Methods:
Of patients referred for treatment of HOCM, 4 had fixed LVOT obstruction. Clinical and echocardiographic data and surgical findings were reviewed.
Results:
In the 4 patients with clinical features consistent with HOCM or HOCM-like conditions, echocardiography showed fixed LVOT obstruction with an early-peaking LVOT Doppler signal or absence of severe systolic anterior motion of the mitral valve. The causes of fixed obstruction included accessory mitral tissue with associated fibrous ring (1 patient), fixed subaortic tunnel stenosis (2 patients), and a discreet subaortic ridge (1 patient). After surgical relief of the fixed LVOT obstruction, all patients had relief of the ventricular outflow tract gradient.
Conclusions:
Not all patients with a presumed diagnosis of HOCM have isolated dynamic LVOT obstruction but may have isolated or additional fixed obstruction. Careful two-dimensional and Doppler echocardiography are needed to identify this subset of patients who are best treated surgically.