What is the management approach for a patient with a sigmoid septum on echocardiogram (echo)?

Management of Sigmoid Septum on Echocardiogram

In most patients with sigmoid septum discovered on echocardiography, no specific treatment is required as this represents a benign age-related morphological change associated with hypertension and aging, but symptomatic patients with left ventricular outflow tract obstruction (LVOTO) should be treated with negative inotropic agents (beta-blockers first-line, with disopyramide as second-line), and surgical intervention should generally be avoided due to risk of severe complications. 1, 2

Initial Assessment and Risk Stratification

Determine Clinical Significance

• Assess for symptoms: Most patients with sigmoid septum are asymptomatic and require no intervention, as this finding represents adverse ventricular-arterial coupling related to age and blood pressure rather than true cardiovascular disease 1

• Evaluate for LVOTO: Measure resting LVOT gradient and perform provocative maneuvers (Valsalva) during echocardiography, as LVOTO may only manifest in hypercontractile states 3, 2

• Look for systolic anterior motion (SAM): SAM of the mitral valve can occur with sigmoid septum and indicates dynamic obstruction, particularly during Valsalva maneuver 3, 4

Distinguish from Hypertrophic Cardiomyopathy

The critical distinction between sigmoid septum and HCM has major management implications:

• Sigmoid septum characteristics: Basal septal hypertrophy with increased angulation between aorta and LV cavity, typically in elderly patients with hypertension history, normal LV septum/posterior wall ratio (approximately 1.0), and hypercontractile LV function 1, 2

• Features favoring HCM over sigmoid septum: Family history of HCM, right ventricular hypertrophy, marked ECG repolarization abnormalities or Q-waves, severe diastolic dysfunction, late gadolinium enhancement at RV insertion points on CMR, and LV septum/posterior wall ratio >1.3 1

• Regression with blood pressure control: If wall thickness decreases with 6-12 months of tight systolic blood pressure control (<130 mmHg), this strongly confirms hypertensive etiology rather than HCM 1

Management Algorithm

Asymptomatic Patients (Majority)

• No specific treatment required: Sigmoid septum without symptoms or LVOTO is a benign finding that does not require intervention 1

• Optimize blood pressure control: Target systolic BP <130 mmHg, as hypertension is the primary underlying etiology 1

• Avoid measurement errors: When measuring LVOT diameter for aortic stenosis assessment, measure closer to the annulus to avoid the septal bulge, as basal septal hypertrophy can confound accurate LVOT measurement 5

Symptomatic Patients with LVOTO

First-line therapy: Beta-blockers

• Initiate beta-blocker therapy (e.g., metoprolol 40-60 mg daily) as first-line treatment for symptomatic LVOTO caused by sigmoid septum 4, 2

• Beta-blockers reduce LVOT gradient by mean of 40.9 mmHg in responsive patients and provide symptomatic improvement in 80% of treated patients 2

Second-line therapy: Disopyramide

• Add disopyramide 200 mg daily if beta-blockers alone are insufficient 4, 2

• Disopyramide provides additional mean reduction of 24.2 mmHg in LVOT gradient in patients who tolerate treatment 2

• Cibenzoline (200 mg daily) has also been reported effective when combined with beta-blockers 4

Avoid surgical intervention

• Myectomy is generally contraindicated: Unlike HCM, surgical myectomy for sigmoid septum carries high risk of severe complications including drastic exacerbation of mitral regurgitation, ventricular septal defect, complete heart block requiring permanent pacemaker, and prolonged mechanical ventilation 6

• Consider PTSMA only in refractory cases: Percutaneous transluminal septal myocardial ablation has been reported successful in isolated cases with dramatic symptom improvement, but experience is extremely limited 3

Critical Perioperative Considerations

Anesthetic Management

• Avoid epinephrine and other positive inotropes: These agents can precipitate or worsen LVOTO and cause severe hemodynamic deterioration in patients with sigmoid septum 7

• Use phenylephrine for hypotension: Pure alpha-agonists increase afterload without increasing contractility, which helps relieve LVOTO 7

• Maintain adequate preload: Volume loading helps maintain LV cavity size and reduces LVOTO 7

• Monitor with TEE when available: Intraoperative transesophageal echocardiography allows real-time diagnosis of LVOTO and SAM, guiding appropriate hemodynamic management 7

Common Pitfalls and Caveats

• Misdiagnosis as HCM: Sigmoid septum can be mistaken for HCM, leading to inappropriate ICD placement or genetic counseling; key distinguishing features are age, hypertension history, normal septal/posterior wall ratio, and absence of family history 1

• Inappropriate use of inotropes: Positive inotropic agents (epinephrine, dobutamine, dopamine) can cause catastrophic hemodynamic collapse in patients with sigmoid septum and should be avoided 7

• Surgical complications: Unlike HCM where myectomy is standard therapy, myectomy for sigmoid septum can cause severe MR exacerbation, VSD, and complete heart block; medical management should be exhausted first 6

• Missed dynamic obstruction: LVOTO may only be apparent with provocative maneuvers (Valsalva, exercise), so resting gradients alone are insufficient to exclude clinically significant obstruction 3

• LVOT measurement errors: Sigmoid septum can cause underestimation of LVOT diameter when measuring too apically, leading to overestimation of aortic stenosis severity by continuity equation 5