The Murmur Newsletter - February 2018

 

 

By: Gina Pasieka, DVM, Diplomate, ACVIM (Cardiology)

 

The Vertebral Heart Scale (VHS) system was developed as a means of evaluating radiographic cardiac silhouette size by indexing heart size to body size using thoracic vertebrae as units of measure. Originally described by Dr. Buchanan, et al in 1991 for the use in dogs, it has since been substantiated in cats, ferrets and other exotic species. It is a quick diagnostic measurement that can be easily added to your daily practice.

How Can We Use VHS?

-VHS can be a useful tool when combined with history and physical exam findings to increase suspicion for the presence of heart disease or to monitor for progression over time. We know that Cavaliers with a VHS >12, with a sudden increased VHS rate of change, were diagnosed with CHF within a 9 month period.

-A VHS >9.3 was found to be highly specific for the presence of CHF in cats with dyspnea. The same study also determined that dyspneic cats with a VHS <8.0 were unlikely to be in heart failure.

-Both the PROTECT (treatment of preclinical DCM) and EPIC (treatment of preclinical MR disease) studies utilized an increased VHS as part of the criteria in determining the appropriate time to start Pimobendan.

Calculating Vertebral Heart Scale

1. Preferentially use a right lateral thoracic radiograph with T4-T12 vertebra clearly visible
2. Take the long axis measurement measuring from the carina of the mainstem bronchus to the apex of the cardiac silhouette
3. Take the short axis measurement at the widest part of the cardiac silhouette perpendicular to the long axis measurement.  For serial radiographic VHS comparison, it is often prudent to select an anatomic landmark for repeatability.  The approximate ventral aspect of the caudal vena cava is often chosen as this specific landmark.
4. Transfer both the long and short axis measurements separately starting at the cranial edge of T4 and count the number of vertebrae that fall within the caliper points
5. Add the two measurements: VHS = W + L

 

Dog	Extent of Cardiomegaly	Cat
8.5-10.7	Normal	6.8-8.1
10.8-11.9	Mild	8.2-8.5
12.0-12.9	Moderate	8.6-8.9
13.0-14.0	Severe	9.0-10.0
>14.0	Extreme	>10.0

 

Known Breed Normals

While the initial study determined normal VHS in dogs to be 8.5-10.7, other studies have shown some breed variations.  You will note that some breed normals lie well outside the originally documented “normal” VHS.

 

 

Breed	Normal	Reference
American Pit Bull Terrier	10.9 +/- 0.4	Lahm et al 2011
Beagle	10.5 +/- 0.4	Kraetschmer et al 2008
Belgian Malinois	9.58 +/- 0.53	Almeida et al 2015
Boston Terrier	11.7 +/- 1.4	Jepsen-Grant et al 2013
Boxer	11.6 +/- 0.8	Lamb et al 2002
Bulldog	12.7 +/- 1.7	Jepsen-Grant et al 2013
Cavalier King Charles	10.6 +/- 0.5	Lamb et al 2001
Dachshund	9.7 +/- 0.5	Jepsen-Grant et al 2013
Doberman	10.0 +/- 0.6	Lamb et al 2002
German Shepherd	9.7 +/- 0.8	Lamb et al 2001
Labrador	10.39 +/- 0.05	Jepsen-Grant et al 2013
Lhasa Apso	9.6 +/- 0.8	Jepsen-Grant et al 2013
Pomeranian	10.5 +/- 0.9	Jepsen-Grant et al 2013
Poodle	10.12 +/- 0.51	Fonsecapinto et al 2004
Pug	10.7 +/- 0.9	Jepsen-Grant et al 2013
Rottweiler	9.8 +/- 0.1	Marin et al 2007
Shih tzu	9.5 +/- 0.6	Jepsen-Grant et al 2013
Whippet	10.8 +/- 0.6	Bavegems et al 2005
Yorkie	9.9 +/- 0.6	Jepsen-Grant et al 2013

 

Other Factors Affecting VHS  

• Some studies have shown a very mild increase in VHS when measuring from the right vs. left lateral radiographs. Consider using the same projection when doing serial monitoring.
• Hemivertebrae could alter the measurement resulting in Bulldogs having higher VHS.
• There is an association between higher VHS and increased body condition scores
• Pericardial effusion in dogs was associated with VHS > 12, but it should also be associated with an increase in sphericity.
• Chronic moderate to severe anemia in both dogs and cats results in compensatory volume overload with an associated increase in VHS.
• Studies have shown normal VHS in puppies over 3 months of age while kittens maintain a higher VHS until 9 months of age.

 

****See last page for Works Cited Sections for “The Vertebral Heart Scale” 

 

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