Brockenbrough-Braunwald-Morrow sign
Brockenbrough-Braunwald-Morrow sign
The Brockenbrough–Braunwald–Morrow sign is a classic hemodynamic finding in hypertrophic obstructive cardiomyopathy (HOCM).
🔑 Key Points:
- Setting: Seen during cardiac catheterization when a premature ventricular contraction (PVC) is followed by a compensatory pause.
- Normal Response: After a PVC, the post-extrasystolic beat is usually stronger (increased stroke volume, stronger pulse pressure).
- In HOCM:
- The post-extrasystolic contraction increases LV contractility, but because of the dynamic LV outflow tract obstruction, instead of an augmented arterial pulse, there is a paradoxical decrease in the aortic pulse pressure.
- This paradoxical fall in pulse amplitude after a PVC is the Brockenbrough–Braunwald–Morrow sign.
🩺 Clinical Importance:
- Pathognomonic for HOCM with dynamic LVOT obstruction.
- Helps distinguish HOCM from fixed LV outflow obstruction (like valvular aortic stenosis), where the post-extrasystolic beat shows a normal rise in pulse pressure.
⚡ Mechanism:
- PVC → pause → increased filling → stronger contraction.
- Strong contraction exacerbates LVOT obstruction in HOCM.
- Result → Aortic pulse pressure falls, despite higher LV contractility.
✅ In summary:
The Brockenbrough–Braunwald–Morrow sign is a paradoxical fall in arterial pulse pressure after a PVC in HOCM, caused by worsening dynamic LVOT obstruction.
Brockenbrough-Braunwald-Morrow sign seen in
[A] Tetralogy of Fallot
[B] Mitral Valve Prolapse
[C] HOCM
[D] Pericardial Tamponade
Brockenbrough-Braunwald-Morrow sign
Brockenbrough–Braunwald–Morrow Sign: MCQs
A. Aortic stenosis
B. Hypertrophic obstructive cardiomyopathy
C. Mitral regurgitation
D. Pulmonary stenosis
It is a hemodynamic sign seen in hypertrophic obstructive cardiomyopathy during catheterization.
A. Increased preload causing enhanced stroke volume
B. Decreased afterload leading to better ejection
C. Post-extrasystolic potentiation with paradoxical fall in pulse pressure
D. Bradycardia-induced augmentation of filling
After a PVC, contractility increases, but in HOCM, obstruction worsens, so arterial pulse pressure falls instead of rising.
A. Cardiac catheterization
B. Echocardiography
C. MRI
D. CT angiography
It is classically demonstrated during cardiac catheterization after inducing a premature beat.
A. Falls significantly
B. Remains unchanged
C. Normal post-extrasystolic potentiation
D. Rises markedly
Post-extrasystolic potentiation increases LV systolic pressure, but paradoxically the arterial pulse pressure drops in HOCM.
A. Aortic stenosis
B. Mitral valve prolapse
C. Tricuspid regurgitation
D. Pulmonary hypertension
In aortic stenosis, the arterial pulse pressure increases after PVC, unlike the paradoxical fall in HOCM.
A. Left atrial
B. Left ventricular
C. Aortic
D. Pulmonary artery
The paradoxical fall is noted in the aortic pressure tracing despite increased LV systolic pressure.
A. Reduced preload
B. Increased contractility with systolic anterior motion of mitral valve
C. Vasodilation
D. Slower heart rate
Post-PVC, the increased contractility accentuates dynamic LVOT obstruction via SAM of the mitral valve.
A. Acute myocardial infarction
B. Chronic hypertension
C. Mitral stenosis
D. Hypertrophic obstructive cardiomyopathy with catheterization
It is specific for HOCM when elicited during invasive hemodynamic study.
A. Fixed subaortic stenosis
B. Hypertrophic obstructive cardiomyopathy
C. Dynamic LVOT obstruction
D. Idiopathic hypertrophic subaortic stenosis
Fixed subaortic obstruction behaves like valvular AS, so it does not demonstrate the paradoxical fall.
A. Assessing mitral regurgitation severity
B. Detecting pulmonary hypertension
C. Differentiating dynamic vs fixed LVOT obstruction
D. Evaluating right heart pressures
It helps distinguish dynamic obstruction in HOCM from fixed obstruction like AS.
A. Braunwald alone
B. Morrow alone
C. Wiggers
D. Brockenbrough, Braunwald, and Morrow
The sign is named after Brockenbrough, Braunwald, and Morrow who described it in HOCM.
A. Falls
B. Rises
C. No change
D. Becomes irregular
Normally, post-extrasystolic potentiation increases stroke volume and aortic pulse pressure.
A. Mitral stenosis
B. Dilated cardiomyopathy
C. Dynamic LVOT obstruction
D. Pulmonary embolism
The paradoxical response confirms the presence of dynamic LVOT obstruction in HOCM.
A. LV systolic pressure
B. Aortic pulse pressure
C. Mean arterial pressure
D. Right atrial pressure
The LV systolic pressure rises post-PVC due to potentiation, but the aortic pulse pressure falls.
A. Bradycardia
B. Increased venous return
C. Decreased contractility
D. Worsened LVOT obstruction
Increased contractility post-PVC worsens the obstruction, reducing forward flow into the aorta.
A. HOCM
B. Valvular aortic stenosis
C. Dynamic subaortic obstruction
D. IHSS
In valvular AS, the expected response post-PVC is increased aortic pulse pressure, not a fall.
A. Mid-diastolic murmur
B. Early diastolic murmur
C. Harsh systolic ejection murmur at left sternal border
D. Continuous murmur
HOCM produces a harsh systolic ejection murmur best heard at the left sternal border.
A. Dynamic LVOT obstruction
B. Pulmonary hypertension
C. Right-to-left shunting
D. Aortic regurgitation
It highlights the dynamic nature of LVOT obstruction in HOCM.
A. Diuretics
B. Inotropes
C. Vasodilators
D. Negative inotropes like beta-blockers
Beta-blockers reduce contractility, alleviating dynamic LVOT obstruction and thus the sign.
A. Coronary angiography
B. Pressure tracings showing LV–aortic gradient post-PVC
C. Echocardiographic Doppler of mitral inflow
D. Right heart catheterization
The hallmark is increased LV systolic pressure but decreased aortic pulse pressure post-PVC, confirming dynamic obstruction.
Published in Methodist DeBakey Cardiovascular Journal 2014 – Alejandro TrevinoJ. Buergler
All of the following are TRUE EXCEPT for the phenomena in above image
[A] Post PVC beat there is Paradoxical decline in arterial pulse pressure
[B] Post PVC Concomitant fall in left ventricular systolic pressure
[C] Seen in HOCM
[D] Post ectopic beat vigorous contraction increases the systolic obstruction and lowers systolic pressure
Mechanism of Brockenbrough-Braunwald-Morrow sign
Ectopic atrial and ventricular beats
- Ectopic atrial and ventricular beats are associated with a prolonged compensatory pause.
- During this pause, more extracellular calcium enters the cardiac muscle cells and gets stored in the sarcoplasmic reticulum.
- Increased concentrations of calcium in myocardial cells cause hypercontractility.
- This leads to a higher systolic and pulse pressure in normal hearts.
In HOCM – vigorous contraction in the post ectopic beat
- Increases the systolic obstruction
- Lowers systolic pressure and pulse pressure
