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Effect of captopril treatment on total and central vascular capacitance in dogs with chronic heart failure

R I Ogilvie1, D Zborowska-Sluis

  • 1Clinical Pharmacology Service, Toronto Hospital, Ontario, Canada.

Journal of Cardiovascular Pharmacology
|September 1, 1994
PubMed

Insights

Captopril treatment improved cardiac preload in dogs with heart failure induced by chronic rapid right ventricular pacing. This study shows potential benefits of converting enzyme inhibition in managing heart failure complications.

Area of Science:

  • Cardiology
  • Pharmacology
  • Physiology

Background:

  • Chronic rapid right ventricular pacing (RRVP) at 250 beats/min induces heart failure characterized by low cardiac output (CO) and reduced vascular capacitance.
  • Heart failure models are crucial for investigating therapeutic interventions.
  • Converting enzyme inhibition is a potential therapeutic strategy for heart failure.

Purpose of the Study:

  • To investigate the effect of converting enzyme inhibition with captopril on cardiac preload in a canine model of heart failure induced by RRVP.
  • To compare the outcomes of captopril-treated dogs with untreated dogs subjected to RRVP.

Main Methods:

  • Eight splenectomized dogs received captopril (6.4 mg/kg daily) for 3 days before and 35 days after RRVP initiation.
  • A control group of 5 untreated dogs underwent RRVP for 32 days.
  • Systemic arterial pressure (Psa), CO, right atrial pressure (Pra), pulmonary capillary wedge pressure (Ppcw), total peripheral resistance (TPR), mean circulatory filling pressures (Pmcf), total vascular compliance and capacitance, and central blood volume (CBV) were measured.

Main Results:

  • Both groups showed similar reductions in Psa and CO, and increases in Pra and TPR.
  • Untreated dogs exhibited higher Ppcw (18.4 vs. 12.1 mm Hg), higher Pmcf (12.6 vs. 8.4 mm Hg), lower vascular compliance (1.9 vs. 2.6 ml/mm Hg/kg), and lower total vascular capacitance (50 vs. 68 ml/kg) compared to treated dogs.
  • Severe ascites occurred in 4 of 5 untreated dogs versus 1 of 8 treated dogs.

Conclusions:

  • Captopril treatment mitigated the adverse effects of RRVP on cardiac preload and vascular capacitance in this heart failure model.
  • Converting enzyme inhibition with captopril demonstrates a protective effect against severe fluid accumulation (ascites) in heart failure.
  • These findings suggest captopril may be beneficial in managing heart failure complications associated with chronic RV pacing.

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