title: Comparative effects of amlodipine and benazepril on left atrial pressure in dogs with experimentally-induced mitral valve regurgitation.
abstract: BACKGROUND
  One of the purposes of treatment for dogs with mitral regurgitation (MR) is lowering left atrial pressure (LAP). There has been few study of the amlodipine in dogs with MR and amlodipine's effect on LAP has not been fully evaluated in a quantitative manner because of difficulties in directly measuring LAP. The objective of our study was to compare the short-term effects of amlodipine (0.2 mg/kg PO q12h) vs benazepril (0.5 mg/kg PO q12h), on LAP and echocardiographic parameters in five beagle dogs with experimentally-induced MR. LAP of eight dogs that has own control were measured using radiotelemetry system at baseline and again on days 1, 2, 3, 4, 5, 6, 7 of the drug administration.
  
  
  RESULTS
  Mean LAP decreased significantly after amlodipine (11.20 ± 4.19 mmHg vs 14.61 ± 3.81 mmHg at baseline, p < .01) but not after benazepril treatment (13.19 ± 3.47 mmHg, p > .05). LAP was lower after 7 days of amlodipine treatment than after 7 days of benazepril treatment. Significant reduction was seen for the first time 4 days after the administration amlodipine. The rate of the maximal area of the regurgitant jet signals to the left atrium area (ARJ/LAA) of the amlodipine treatment was significantly lower (p < .05) after 7 days compared to baseline. Other echocardiographic parameters did not change significantly.
  
  
  CONCLUSIONS
  LAP was significantly decreased after amlodipine treatment in dogs with surgically-induced MR but not after benazepril treatment. Although this study did not focus on adverse effects, amlodipine may be an effective drug for helping the patients with acute onset of severe MR, such as rupture of chordae tendinae or end stage patients were the LAP is likely to be elevated. Additional studies in clinical patients with degenerative mitral valve disease and acute chordal rupture are warranted because the blood-pressure lowering effects of amlodipine can decrease renal perfusion and this can further activate the RAAS.
authors.affiliation: Department of Veterinary Surgery, Faculty of Veterinary Medicine, Tokyo University of Agriculture and Technology, Tokyo, Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Suzuki
authors.forename: Ryuji
authors.initials: R
authors.lastname: Fukushima
authors.forename: Taisuke
authors.initials: T
authors.lastname: Ishikawa
authors.forename: Yuta
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Lina
authors.initials: L
authors.lastname: Hamabe
authors.forename: Soomin
authors.initials: S
authors.lastname: Kim
authors.forename: Rieko
authors.initials: R
authors.lastname: Yoshiyuki
authors.forename: Noboru
authors.initials: N
authors.lastname: Machida
authors.forename: Ryou
authors.initials: R
authors.lastname: Tanaka
mesh_terms: D017311:Amlodipine / Q000494:pharmacology*; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D016279:Atrial Function, Left / Q000187:drug effects*; D001552:Benzazepines / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D004285:Dogs; D004452:Echocardiography; D005260:Female; D008297:Male; D008944:Mitral Valve Insufficiency / Q000473:pathology / Q000662:veterinary*
chemical_list: D000959:Antihypertensive Agents; D001552:Benzazepines; D017311:Amlodipine; C044946:benazepril