1) High output heart failure presents with classic signs and symptoms of volume overload and is characterized hemodynamically by high cardiac output (in the case we discussed today, CI of 16! where normal is 2.4 to 4 L/min/m^2) and very low calculated systemic vascular resistance.
2) Clinical high output heart failure is generally associated with flow through a fistula of greater than 2L/min.
3) The most common causes of high output heart failure in a Mayo Clinic series of 120 patients diagnosed between 2000 and 2014:
- Morbid Obesity (31%)
- Liver disease (22.5%), particularly cirrhosis
- AV shunts (22.5%)—including AV fistulas for dialysis, Hereditary Hemorrhagic Telangiectasia, Renal cell carcinoma, traumatic including iatrogenic from say groin access in cardiac cath or other surgical procedure
- Lung disease (16%)
- Myeloproliferative disorders (8%)
- Other important causes: anemia, hyperthyroidism, sepsis, Beriberi (thiamine/B1 deficiency), carcinoid, pregnancy
4) Nicoladoni-Branham sign: exaggerated Bezold-Jarisch reflex or a decrease in heart rate and increase in blood pressure that immediately follows the sudden occlusion of an arteriovenous (A-V) fistula. Since its description in 1890, it has been considered the standard test of the hemodynamic significance of an A-V fistula.
5) Complications of AV fistulas to be aware of with their associated exam findings (to be confirmed radiologically):
- Venous/arterial stenosis- local edema, strong pulse over the fistula decreased augmentation of the pulse (occlude fistula and the pulse is stronger a short distance away normally, but this will be less in stenosis)
- Infections- small pustular lesions if superficial, cellulitic appearance if deeper
- Aneurysm- rapidly enlarging bulge
- Ischemia/Steal Syndrome- hand ischemia with cyanosis, coolness, and diminished radial pulse