Key result
Intravenous diltiazem constant rate infusion in healthy dogs resulted in a significantly lower systolic time interval compared to D5W (median 0.30 vs 0.32; P=0.046).
Why the study?
To determine whether echocardiographic LV systolic function, systemic blood pressure, and ECG findings change with an IV diltiazem constant rate infusion compared to control.
Does an intravenous continuous rate infusion of diltiazem decrease systolic function in healthy dogs?
RCT (n=10)
masked
randomized crossover
Does an intravenous continuous rate infusion of diltiazem decrease systolic function in healthy dogs?
In healthy dogs, a clinically accepted intravenous continuous rate infusion of diltiazem does not significantly decrease left ventricular systolic function or cause hypotension.
Diltiazem CRI does not impair LV systolic function in healthy dogs; leaves open effects in diseased hearts or clinical outcomes.
OBJECTIVE: To determine if left ventricular systolic function on echocardiography, systemic blood pressure, and electrocardiography change with a clinically accepted intravenous (IV) diltiazem constant rate infusion (CRI) compared to a control. ANIMALS: 10 healthy client-owned adult dogs. PROCEDURES: Prospective, masked, crossover study from May 27, 2021, to August 22, 2021. Dogs were randomized to receive diltiazem (loading dose of 240 μg/kg, IV followed by a CRI of 6 μg/kg/min for 300 minutes) or the same volume of 5% dextrose in water (D5W) administered IV followed by the opposite intervention after a 7-day washout. Blood pressure was monitored during each CRI, and echocardiographic and electrocardiographic studies were performed immediately before the CRI and during the last hour of the CRI. RESULTS: Postdiltiazem systolic time interval (STI) (median, 0.30; range, 0.16 to 0.34) was significantly lower than post-D5W STI (median, 0.32; range, 0.22 to 0.40; P = .046). All other echocardiographic parameters did not differ significantly between each of the groups after receiving diltiazem or D5W. Systemic blood pressure did not change significantly with either diltiazem (P = .450) or D5W (P = .940), and none of the dogs became hypotensive at any point in the study. Expectedly, negative dromotropy was observed with diltiazem. CLINICAL RELEVANCE: A significant decrease in left ventricular systolic function was not appreciated in healthy dogs receiving diltiazem at a clinically accepted intravenous infusion rate at this dosing regimen. Further studies are needed in dogs with cardiac disease.
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Whitehouse et al. (2023) conducted an RCT in healthy dogs (n=10). diltiazem vs. 5% dextrose in water (D5W) was evaluated on systolic time interval (STI) (p=.046). Intravenous diltiazem constant rate infusion in healthy dogs resulted in a significantly lower systolic time interval compared to D5W (median 0.30 vs 0.32; P=0.046).
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