Page 294 - Clinical Small Animal Internal Medicine

262 Section 3 Cardiovascular Disease

should be initiated for rate control before dobutamine to Holter is advised within 1–2 weeks to assess VA control
VetBooks.ir avoid life‐threatening tachycardia. Dobutamine is typi- or rate control in the case of AF, and medications adjusted
accordingly. One cannot expect to eliminate VA but
cally administered for <72 hours due to the development
of receptor refractoriness. If dobutamine is not available
is a reasonable goal (preferably reduction of >80%). In
or feasible, then oral pimobendan should be started as rather a reduction of the frequency, complexity, and HR
soon as possible. the case of AF, HR targets must be individualized to what
Sodium nitroprusside is a potent mixed vasodilator appears to be optimal for the patient based on the assess-
that may be added as a CRI for the treatment of severe ments above, but a general guideline is a target mean HR
life‐threatening edema. Blood pressure must be moni- <125 bpm on Holter or <140–150 bpm in hospital.
tored very frequently, preferably invasively and continu-
ously. Side‐effects include hypotension (which can be Prognosis
quickly resolved by stopping or decreasing the dose due
to its very short duration of action), and rarely cyanide Dogs with preclinical disease may go several years with-
toxicity with high dose and prolonged use (>72 hours). out clinical signs, so the diagnosis does not imply imme-
With the initiation of all of these infusions, careful atten- diate risk of morbidity or mortality. Data on the length of
tion must be paid to the volumes of fluids being admin- this phase are lacking for most breeds except the
istered, and solutions should be concentrated as much as Doberman and IW. Based on the PROTECT trial, the
possible to reduce the total volume being administered. median time to CHF or SD following diagnosis of occult
Following stabilization, weaning of IV medications and disease in Dobermans was 718 days in the pimobendan‐
transition to the oral medications discussed above (as for treated group and 441 in the placebo group. IW may
outpatient) is carried out. have a very prolonged preclinical phase, with an average
For the refractory CHF patient (those with advanced of 48 months in a recent clinical trial.
CHF that continue to have clinical signs despite standard Unless a reversible underlying cause is identified (e.g.,
therapy – ACVIM stage D), management strategies taurine deficiency, primary tachyarrhythmia), the prog-
include confirming owner compliance with current nosis for DCM is often poor once overt clinical disease
medications, identifying complicating concurrent condi- (CHF) develops, with most survival times being in
tions (poorly controlled or new arrhythmias, systemic months. The median survival time in a large retrospec-
diseases such as hyperadrenocorticism, neoplasia, infec- tive study with mostly overt dogs was 19 weeks, with
tious or inflammatory conditions), and changing medi- one‐year and two‐year survival rates of 28% and 14%,
cation strategies. The latter can include an increase in respectively. Fifty percent of dogs were euthanized for
the frequency or change in route of furosemide adminis- their heart disease in this study, while 40% died from
tration (IV bolus or CRI for short periods), addition of their heart disease, and 3% died for other reasons,
diuretics such as spironolactone or hydrochlorothiazide emphasizing the almost inevitably terminal nature of
(the latter should be accompanied by a reduction in furo- this disease. In the Doberman, one‐year survival rates of
semide dose), stricter sodium restriction, increase in 10% or less have been reported, and treatment with tri-
inodilator and/or ACEI dose, or short‐term parenteral ple therapy (ACEI, furosemide, pimobendan) yielded a
positive inotrope (dobutamine) or vasodilator (nitro- median survival time of 130 days. IW may have a better
prusside) administration as described above. prognosis once in CHF, with median survival time
of five months in those dying of their disease but
Follow‐up/Monitoring of Overt DCM 14 months in those still alive at the time of writing of
The focus of follow‐up is respiratory status (respiratory one study.
rate and effort, degree of pulmonary edema or pleural Factors associated with shorter time to CHF or SD in
effusion on thoracic radiography), renal status and elec- the PROTECT trial included an increase in LVESD
trolyte balance (renal chemistry and electrolytes), body index, increased baseline HR, and ≥4 VPCs on a 3‐min
condition and hydration (body weight, body condition ECG. Factors associated with negative prognosis in overt
score [BCS]), HR and rhythm (auscultation, ECG or DCM have included increased LVESV index, decreased
Holter), and perfusion (body temperature, blood pres- EF, presence of pulmonary edema on radiographs, pres-
sure, renal chemistry, electrolytes). These assessments ence of ascites, presence of VPCs on ECG, increased
may be made as frequently as weekly at the initiation of serum creatinine, decreased plasma protein, Great Dane
therapy to every 1–2 months once patients are stable. breed, and restrictive transmitral flow pattern on
While ACEI and pimobendan doses are often optimized Doppler echocardiography. Factors associated with
at the onset, diuretic doses are adjusted to balance pul- increased risk of SD in Dobermans include larger LVEDV,
monary and renal/hydration needs. Following initiation presence of VT, VPCs with instanteous HR ≥260 bpm,
of or change in dose of AAs, recheck ECG or ideally and higher cTnI.