Page 328 - Feline Cardiology

Chapter 21: Systemic Hypertension 337

Candidate for antihypertensive therapy
Treat existing TOD & concurrent diseases
Institute disease-specific therapy, where appropriate

Avoid high dietary NaCl intake

Consider disease-specific antihypertensives for
chronic kidney disease, hyperthyroidism,
pheochromocytoma, hyperaldosteronism

Institute first agent

Re-evaluate in 7-10 days (1-3 days if emergency):
Has BP reached target risk level without side effects?

Yes No

Re-evaluate Hypotensive (BP < 120/80 mmHg) Risk category too high: Increase dosage
in 1-3 months or other side effects: reduce interdose interval,
Decrease dosage, increase interdose interval, - OR -
or change therapeutic agent(s). add another agent
Re-evaluate at appropriate interval.

Re-evaluate in 7-10 days
(1-3 days if emergency):
Has BP reached target
risk level without side effects?

Yes No Systemic Hypertension
Figure 21.11. Algorithm demonstrating the process of treatment decision-making in animals with systemic hypertension. Reproduced
with permission from ACVIM Consensus Statement.

pertensive medications may be initiated if systemic certain to try and reduce it’ ” (Hay 1931). Accordingly,
hypertension persists. Fourth, follow­up is undertaken the first step in treating cats with systemic hypertension
and the approach is adjusted based on progress and is to ensure that they are indeed truly and repeatably
subsequent results. Patients with successfully managed pathologically hypertensive (see “Differential Diagnosis,”
systemic hypertension rarely show dramatic, immediate above) and that hypertensive diseases are optimally
improvements. Rather, the signs of success for treatment managed.
of hypertension include maintenance of the status quo The optimal approach to treating systemic hyperten­
if decompensation has never occurred, or if it has, sta­ sion in cats is presented in Figure 21.11. Once extrane­
bilization and gradual improvement without relapse. ous artifacts that might have increased BP readings are
Systemic hypertension must be confirmed to be real eliminated and underlying diseases are properly
(accurate measurement of BP) prior to initiation of BP­ managed, the drug of choice for treatment of persistent
lowering drugs. While delayed implementation of anti­ hypertension is amlodipine (Norvasc; available in 2.5 mg
hypertensive therapy can allow life­threatening ocular tablets). A typical initial dosage is 0.625 mg [1/4 tablet]
or intracranial crises to develop, the reverse situation PO q 24 h for most cats, and this is adjusted based on
where patients who are not truly hypertensive are inad­ response. A mean decrease in systolic BP from 198 mm Hg
vertently given antihypertensive medications is equally to 155 mm Hg was noted in spontaneously hypertensive
troublesome and possibly more common. Hay was cats receiving amlodipine 0.08–0.23 mg/kg PO q 24 h,
probably observing poor control of confounding factors, with some authors recommending up to double this
and resultant overdiagnosis of systemic hypertension, amount if both warranted and clinically tolerated by the
when writing, in 1930: “There is some truth in the saying patient. Amlodipine has demonstrated efficacy in hyper­
that the greatest danger to a man with a high blood tensive cats, both with regard to direct blood pressure­
pressure lies in its discovery, because ‘then some fool is lowering effects (Henik et al. 1997) and improvement in