Brockenbrough phenomenon

Brockenbrough phenomenon

Brockenbrough–Braunwald–Morrow Sign — MCQs

Q1. The Brockenbrough–Braunwald–Morrow sign is most classically associated with which condition?
In HOCM, post-extrasystolic beats increase contractility but worsen dynamic LVOT obstruction, causing a paradoxical fall in aortic pulse pressure.
Q2. During catheterization, what paradoxical observation defines the sign after a PVC?
After a PVC, LV contractility rises, but dynamic LVOT obstruction worsens, so aortic pulse pressure paradoxically falls.
Q3. Which invasive procedure is used to elicit the Brockenbrough sign?
Simultaneous LV and aortic pressure tracings are required to observe the paradoxical fall in aortic pressure after a PVC.
Q4. What hemodynamic change after a PVC contributes to demonstrating the sign?
PVC produces a compensatory pause, increasing filling and causing post-extrasystolic potentiation, which worsens LVOT obstruction.
Q5. How does this sign differentiate HOCM from fixed aortic stenosis?
Fixed aortic stenosis increases stroke volume post-extrasystole, raising aortic pressure; paradoxical fall is specific to HOCM.
Q6. Which pressure tracing pattern is observed with the sign?
LV contracts more forcefully after PVC, but dynamic obstruction reduces aortic pressure.
Q7. Which structural abnormality underlies dynamic LVOT obstruction producing this sign?
Dynamic LVOT obstruction is caused by asymmetric septal hypertrophy and SAM of the mitral leaflet narrowing the outflow tract.
Q8. Which maneuver likely augments the Brockenbrough sign?
Reducing preload/afterload reduces LV cavity size, worsening obstruction (Valsalva, nitrates).
Q9. Which drug would reduce the Brockenbrough sign by lessening dynamic obstruction?
Beta-blockers reduce contractility and heart rate, decreasing SAM and LVOT obstruction.
Q10. Post-extrasystolic LV pressure increase with DECREASED aortic pressure indicates:
This pattern is classic for dynamic LVOT obstruction in HOCM.
Q11. True or False: The Brockenbrough sign can be observed noninvasively on cuff BP after a PVC.
Catheterization is required; noninvasive measurements are unreliable.
Q12. What does “post-extrasystolic potentiation” refer to?
The beat following an extrasystole has increased contractility due to calcium handling and longer filling time.
Q13. Echocardiographic finding commonly accompanying the sign?
SAM of the mitral valve contributes to dynamic LVOT obstruction producing the Brockenbrough sign.
Q14. Most accurate clinical use of the Brockenbrough sign?
It is an invasive confirmation during catheterization when LV and aortic tracings are recorded.
Q15. Expected pressure change during post-extrasystolic beat in HOCM?
LV generates higher pressure, but dynamic obstruction reduces downstream aortic pressure.
Q16. Which intervention acutely relieves dynamic obstruction?
Beta-blockers reduce contractility and heart rate, increasing LV filling and reducing obstruction.

Brockenbrough–Braunwald–Morrow Sign — MCQs

Q17. The Brockenbrough–Braunwald–Morrow sign is most classically associated with which condition?
In HOCM, a post-extrasystolic beat increases contractility but worsens dynamic LVOT obstruction producing a paradoxical fall in aortic pulse pressure — the Brockenbrough–Braunwald–Morrow sign.
Q18. During catheterization, what is the paradoxical observation that defines the sign after a PVC?
After a PVC the LV contractility rises, but in HOCM the dynamic outflow tract obstruction worsens so the aortic pulse pressure falls despite increased LV pressure.
Q19. The Brockenbrough–Braunwald–Morrow sign is elicited during which invasive procedure?
The sign requires simultaneous LV and aortic pressure tracings (left-sided catheterization) to observe the paradoxical fall in aortic pressure relative to LV pressure after a PVC.
Q20. Which immediate hemodynamic event following a PVC contributes to demonstrating the sign?
PVC produces a compensatory pause, increasing diastolic filling and leading to post-extrasystolic potentiation — a stronger LV contraction which worsens dynamic LVOT obstruction in HOCM.
Q5. How does the Brockenbrough–Braunwald–Morrow sign help differentiate HOCM from fixed aortic stenosis?
In fixed aortic stenosis the post-extrasystolic beat increases stroke volume and aortic pulse pressure; the paradoxical fall is specific to dynamic obstruction like HOCM.

The Brockenbrough phenomenon, also known as the Brockenbrough-Braunwald-Morrow sign, is a diagnostic finding in patients with hypertrophic obstructive cardiomyopathy (HOCM). It is a paradoxical response to a premature ventricular contraction (PVC), characterized by a decrease in arterial pulse pressure following the ectopic beat. 

The paradoxical response

To understand the Brockenbrough phenomenon, it is useful to compare a healthy heart’s response to a PVC with that of an HOCM heart.

 Normal HeartHOCM Heart
Response to PVCA PVC is followed by a compensatory pause, which gives the left ventricle extra time to fill with blood. Following the Frank-Starling law, the longer diastolic filling time leads to an increase in the next contraction’s force and stroke volume.The compensatory pause still occurs, and the extra filling time increases the force of the next contraction. However, in HOCM, the augmented contraction causes the muscular septum and mitral valve to obstruct the left ventricular outflow tract (LVOT).
Resulting Pulse PressureThe stronger contraction and increased stroke volume lead to a stronger pulse and a wider arterial pulse pressure following the PVC.The LVOT obstruction dramatically decreases the amount of blood that can be ejected from the ventricle. This leads to a paradoxical decrease in the arterial pulse pressure, despite a stronger ventricular contraction.

Clinical significance

The Brockenbrough phenomenon is an important sign for diagnosing and managing HOCM. 

  • It distinguishes the condition from other causes of LVOT obstruction, such as fixed valvular aortic stenosis, where the pulse pressure typically increases after a PVC.
  • Since many HOCM patients do not have a resting gradient, this maneuver can be used during a cardiac catheterization to confirm dynamic LVOT obstruction.
  • It can also be used during and after invasive procedures, such as alcohol septal ablation or surgical myectomy, to determine the degree of obstruction and confirm the success of the treatment. 
  • Query successful

The Brockenbrough phenomenon, more formally known as the Brockenbrough-Braunwald-Morrow Sign, is a specific hemodynamic finding used in the diagnosis of Hypertrophic Obstructive Cardiomyopathy (HOCM).

Brockenbrough Phenomenon

The phenomenon describes a paradoxical response in the heart’s pressures during the beat immediately following a Premature Ventricular Contraction (PVC) or other premature beat.

Normal Post-PVC ResponseBrockenbrough Phenomenon (HOCM)
Arterial Pulse Pressure: ↑ (Increase)Arterial Pulse Pressure: ↓ (Decrease)
Left Ventricular (LV) Systolic Pressure: ↑ (Increase)LV Systolic Pressure: ↑ (Increase)
LV Outflow Tract (LVOT) Gradient: Remains low or absentLVOT Gradient: ↑ (Increases significantly)

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Mechanism

  1. Premature Contraction (PVC): An ectopic beat occurs, followed by a compensatory pause (a longer-than-normal delay before the next beat).
  2. Increased Preload: The prolonged pause allows for increased diastolic filling of the left ventricle, leading to a greater end-diastolic volume (EDV).
  3. Post-Extrasystolic Potentiation: According to the Frank-Starling mechanism, the greater stretch from the increased EDV leads to a more forceful subsequent contraction (increased contractility).
  4. Paradoxical Response in HOCM: In a normal heart, this more forceful contraction would increase the stroke volume and thus the arterial pulse pressure. However, in HOCM, the greater force:
    • Worsens LVOT Obstruction: The forceful contraction causes the hypertrophied septum and the mitral valve leaflet (Systolic Anterior Motion or SAM of the mitral valve) to obstruct the outflow tract more severely.
    • Increases LV Pressure/Gradient: This increased obstruction leads to a significant increase in the pressure within the left ventricle (high LV systolic pressure) to push blood out.
    • Decreases Arterial Pulse Pressure: Due to the severe obstruction, less blood is ejected into the aorta (decreased stroke volume), which causes a drop in the arterial pulse pressure despite the forceful LV contraction.

Clinical Significance

The presence of the Brockenbrough sign is highly suggestive of dynamic left ventricular outflow tract obstruction, a characteristic feature of Hypertrophic Obstructive Cardiomyopathy (HOCM). It is typically documented in a cardiac catheterization laboratory by simultaneously measuring the left ventricular and aortic pressures.

The second part of your request, “table cl points”, is not standard medical terminology related to the Brockenbrough phenomenon. Assuming you were asking for the Chemical or Critical Limits/Points related to the phenomenon or HOCM diagnosis, the relevant values are hemodynamic gradients:

Critical Hemodynamic Points (Gradients)

MeasurementCritical Value (CL)
Resting LVOT Gradient≥30 mmHg
Provoked LVOT Gradient≥50 mmHg
Brockenbrough SignParadoxical decrease in arterial pulse pressure with a concomitant increase in LV systolic pressure after a PVC, often resulting in a post-PVC gradient of ≥30 mmHg or more (confirming dynamic obstruction).

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