MOFFITT CARDIOLOGY REPORT PEARLS 3/14/17: High-Output Heart Failure and Ashman Phenomenon!

Thanks to Kat and Neal for presenting two interesting cases for cardiology report! We’ll focus today’s pearls on some questions that came up during our discussion:

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Top Pearls:

  1. In an anemic patient with signs of volume overload, consider high-output heart failure.
  2. In a young patient with a-fib and no structural heart disease, consider an accessory pathway.
  3. Ashman phenomenon is a rate-dependent RBBB in atrial fibrillation.

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For those who want more info:

High-Output Heart Failure:

Definition: Heart failure with elevated cardiac output. Though cardiac output should be normalized to body size, generally a normal CO at rest is approximately 5-6L/min, so anything above that range is high-output. To normalize for body size, calculate the cardiac index (CI = CO/BSA). High-output is best defined by resting cardiac index above the normal range (2.5-4L/min/m2).

Clinical Manifestations: HR is usually 85-105 bpm but is often higher with some causes such as thyrotoxicosis. Look for a bounding pulse with quick upstroke, widened pulse pressure, “pistol-shot” sounds auscultated over the femoral arteries (Traube’s sign), subungual capillary pulsations (Quincke’s pulse), enlarged heart on exam, a mid-systolic murmur, and an S3 due to increased rate of ventricular filling.

Causes:

  • Physiologic (excitement, anxiety, stress, exercise, pregnancy, fever)
  • Morbid obesity

 

  • AV shunts (HD fistula, HHT, Paget disease of bone, RCC)
  • Cirrhosis

 

  • COPD and CTD involving the lungs
  • Leukemia, MM, myelofibrosis
  • Sepsis
  • Hyperthyroidism
  • Anemia (as in the case we discussed today)

 

  • Wet beriberi (thiamine deficiency)
  • Carcinoid
  • Severe dermatologic disorders (e.g. psoriasis)

The most common causes are obesity (30%), cirrhosis (22%), AV shunts (22%), lung disease (16%), and myeloproliferative disorders (8%).

 

Atrial Fibrillation in a Young Person:

We came up with a differential with YY’s help:

  • Structural heart disease (LAE, MVP, MR, MS, cardiac mass, cor triatrium)
    • Hypertrophic CM (the most common associated arrhythmia is a-fib!)
  • Metabolic disorders (hyperthyroidism, catecholamine excess)
  • Substances (alcohol, drugs, caffeine)
  • WPW

 

  • Familial a-fib

 

Ashman Phenomenon:

Ashman phenomenon is a rate-related bundle branch block in atrial fibrillation. Usually it will be RBBB because the RBB generally has a longer refractory period than the LBB.

The His Purkinje refractory period normally shortens as the heart rate increases (so our ventricular rate can actually speed up as needed, e.g. for exercise!) and lengthens as the heart rate slows. In a-fib, where the R-R intervals change with each beat, the refractory period can change beat to beat as well. If there is a “long cycle” (ie. a long R-R interval), the refractory period (particularly of the RBB) will lengthen, and thus the beat following the long cycle will have a RBBB pattern.

It can be tough to distinguish Ashman phenomenon from a PVC. Ashman should have a long RR followed by a short RR with a RBBB pattern, as pictured below:

Ashman_phenomenon_in_AF

 

Evernote: https://www.evernote.com/shard/s272/sh/aaa4d908-8027-4300-8e0d-c3544f85b49e/25ece8f137aa284e316b2d1442dcdf40

 

Have a great day everyone!

SamMy

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