The Effect of Furosemide on Left Atrial Pressure in Dogs with Mitral Valve Regurgitation

Abstract

Background: The effects of furosemide on left atrial pressure (LAP) in dogs with mitral regurgitation (MR) have not been documented in a quantitative manner and between different routes of administration.Objective: To document LAP and echocardiographic parameters in MR dogs administered furosemide IV or PO, in order to document changes in LAP after furosemide treatment.Animals: Five healthy Beagle dogs (3 males and 2 females; aged 2 years) were used. Methods: Experimental, cross-over, and interventional study. LAP was measured before the administration of furosemide, and 30 minutes, 1, 1.5, 2, 3, 4, 5, 6, 8, 12, and 24 hours after administration. Furosemide 1, 2, or 4 mg/kg IV, PO or placebo was administered.Results: LAP was significantly decreased with all administrations of furosemide but not after placebo (P o .05, respectively). The max reduction was observed 1 hour (1 mg/kg IV, 15.04 AE 7.02 mmHg), 3 hours (2, 4 mg/kg IV, 13.28 AE 8.01, 9.23 AE 4.92 mmHg), 4 hours (1 mg/kg PO, 14.68 AE 11.51 mmHg), and 5 hours (2, 4 mg/kg PO, 13.19 AE 10.52, 10.70 AE 7.69 mmHg). E wave and E/Ea were significantly decreased corresponding to the reduction of LAP after administration of 2 and 4 mg/kg (P o .05, respectively).Conclusions and Clinical Importance: LAP was decreased in proportion to the dosage of furosemide, which did not significantly differ between IV and PO of the same dosages. E wave and E/Ea might be useful for the treatment evaluation of furosemide.Key words: Radio telemetry system; Total circulating blood volume; Transmitral blood flow.M itral valve disease is the most common cardiac disease in dogs. As many as three quarters of all dogs with signs of congestive heart failure suffer from mitral regurgitation (MR) caused by myxomatous degeneration of the valve leaflets or the chordae tendineae.1,2 MR increases the left atrial pressure (LAP) which potentially results in left atrial dilation. Elevated LAP causes pulmonary edema that can lead to cough, dyspnea, and even death.3 Therefore, LAP needs to be reduced to avoid these clinical signs.Furosemide, a loop diuretic, has a strong diuretic effect and is commonly used for the treatment of pulmonary edema in patients with MR. 4 Furosemide reduces the total circulating blood volume, which in turn reduces the LAP or the left ventricular filling pressure, and leads to the clinical improvement of the patients. [5][6][7][8][9] There are several administration routes for furosemide, including IV, PO, SC, and IM. Pharmacokinetics of furosemide has been compared between IV and PO administration. However, the effects of furosemide on LAP in dogs with MR have not been well documented in a quantitative manner because there are some difficulties in measuring LAP directly. We have previously reported the 24-hour LAP profiles of and the effect of angiotensin-converting enzyme (ACE) inhibitors on experimentally induced MR dogs with a radio telemetry system. 10,11 The previous study has demonstrated that this system is useful for the evaluation of hemodynamic changes that occur...

Effects of a Sustained‐Release Form of Isosorbide Dinitrate on Left Atrial Pressure in Dogs with Experimentally Induced Mitral Valve Regurgitation

“…In this study, LAP was significantly decreased by administration of 5 and 10 mg/kg sr‐ISDN. Compared with our previous study, the effect of high‐dose sr‐ISDN on reducing the maximum values of LAP was nearly equal to that of diuretic . This result suggests that high dose of sr‐ISDN has a significant effect on LAP.…”

“…The dogs underwent a surgical procedure to induce MR, and a transmitter catheter was implanted in the left atrium. The surgical procedure and postoperative care were conducted according to our previous report . Thoracic radiography and echocardiography were performed to evaluate pulmonary venous congestion and cardiac dilatation.…”

“…Measurement parameters were left atrial to aortic root ratio (LA/AO), left ventricular end‐diastolic diameter (LVEDD), fractional shortening (FS), forward stroke volume (SV), cardiac output (CO), peak transmitral early diastolic wave (E wave) velocity, and mitral annulus velocities (Ea). The procedure of echocardiographic measurements was conducted according to our previous report . All the echocardiography recordings were stored on the internal hard drive of the echocardiograph and transmitted to the DICOM server online…”

Comparative effects of amlodipine and benazepril on Left Atrial Pressure in Dogs with experimentally-induced Mitral Valve Regurgitation

“…Other echocardiographic parameters did not change significantly. We previously have reported that E wave and E/Ea can be used for the evaluation of preload after administration of high doses of furosemide, and have monitored the reduction of LAP in the short-term [16]. However, present study suggests that it is difficult to evaluate the reduction of LAP after administration of amlodipine by using E wave and E/Ea.…”

“…However, 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. We have previously used a radiotelemetry system to report the effects of angiotensin-converting enzyme (ACE) inhibitors and furosemide in dogs with experimentally-induced MR [14-16], and we believe this system would be useful for evaluation of hemodynamic changes after administration of amlodipine.…”