Echocardiographic Estimation of Left Atrial Pressure in Beagle Dogs with Experimentally-Induced Mitral Valve Regurgitation

Abstract

ABSTRACT. Non-invasive and immediate estimation of left atrial pressure (LAP) is very useful for the management of mitral regurgitation (MR), and many reports have assessed echocardiographic estimations of LAP to date. However, it has been unclear of which examination and evaluate article possess the best accuracy for the MR severity. The present research aims to establish the echocardiographic estimation equation of LAP that is well applicable for clinical MR dogs. After the chordae tendineae rupture was experimentally induced via left atriotomy in six healthy beagle dogs (three males and three females, two years old, weighing between 9.8 to 12.8 kg), a radio telemetry transmitter catheter was inserted, which allows the continuous recordings of LAP without the use of sedation. Approximately 5 weeks after the surgery, echocardiographic examination, indirect blood pressure measurement, measurement of plasma atrial natriuretic peptide (ANP) and LAP measurement by way of the radio telemetry system was performed simultaneously. Subsequently, simple linear regression equations between LAP and each variable were obtained, and the equations were evaluated whether to be applicable for clinical MR dogs. As a result, the ratio of early diastolic mitral flow to early diastolic lateral mitral annulus velocity (E/Ea) had the strongest correlation as maximum LAP=7.03*(E/Ea)-54.86 (r=0.74), and as mean LAP=4.94*(E/Ea)-40.37 (r=0.70) among the all variables. Therefore, these two equations associated with E/Ea should bring more precise and instant estimations of maximum and mean LAP in clinical MR dogs.KEY WORDS: atrial natriuretic peptide, mitral annulus velocity, mitral inflow, radio telemetry system. J. Vet. Med. Sci. 73(8): 1015-1024, 2011 Mitral valve regurgitation (MR), secondary to degenerative mitral valve apparatus disease (MVD), is one of the most common cardiac disorders in dogs [1]. Although surgical interventions such as mitral valve repair [11] and replacement [3] have been reported, most owners do not pursue these surgical options due to the cost or the small number of facilities able to perform such interventions. Therefore, most patients follow appropriate drug therapy on the basis of adequate evaluation of clinical symptoms.In dogs with moderate to severe MR, left atrial pressure (LAP) rises markedly as a result of volume overload and regurgitation [1,27]. Echocardiography has been one of the most valuable modalities for evaluating left atrial and ventricular dilation and slower MR velocity which is caused by the elevated LAP [7]. A number of reports have described the echocardiographic estimation of LAP and its alternative, which is the left ventricular filling pressure (LVFP), in humans [5,6,20] and in veterinary medicine [21,26]. Recently, the usefulness of isovolumic ventricular relaxation time (IVRT) [24], pulmonary venous flow (PVF) [14], plasma atrial natriuretic peptide (ANP) concentration [2,17] and tissue Doppler imaging (TDI) [10] have also been reported as noninvasive assessment of LAP in volume ove...

Evaluation of Left Ventricular Function in Healthy Retrievers Using Standard and 2D Speckle-Tracking Echocardiography

“…TDI-derived E/E′ was demonstrated to be a good indicator of increased LA pressure, caused by volume overload and mitral regurgitation, and an important predictor of congestive heart failure in dogs with myxomatous mitral valve disease [ 1 , 29 ]. The MPI, also obtained via TDI, is a comprehensive index of global myocardial function, which was demonstrated to correlate well with both systolic and diastolic cardiac performance in dogs [ 1 , 30 ].…”

Right ventricular systolic and diastolic function assessed by two-dimensional speckle tracking echocardiography in dogs with myxomatous mitral valve disease

“…Even in asymptomatic dogs without substantial left heart remodeling due to MMVD, cases with echocardiographic findings indicating increased left atrial pressure were classified into the B1 group and the respective PH probability groups. Increased left atrial pressure was estimated according to increased early-diastolic transmitral flow velocity (>1.4 m/s) and ratio of early-diastolic transmitral flow velocity to early-diastolic myocardial velocity of the septal mitral annulus (>13) [17,32,38]. Peak TR velocity was obtained from the right parasternal long-axis view, short-axis view at the level of the heart base, and/or the left parasternal apical four-chamber view [13,31,44].…”

Echocardiography

“…This image is often obtained from a right parasternal long-axis view (see Figure 8-44, C). 181,306 However, the ratio of E/E' that predicts CHF is probably higher than for cardiomyopathy, likely in the range of 13 to 15 in chronic, spontaneous disease, 148 similar to values observed in people with primary MR. 299 Lower ratios (>9.1) predicted a mean LA pressure of >20 mm Hg in experimental MR of acute onset, 308 emphasizing the need to tailor the "ratios" for the underlying disease and chronicity when attempting to predict elevated pulmonary venous pressures. Some examiners prefer to turn off tur-with E/A reversal (Grade 1 diastolic dysfunction) is good evidence for mild MR and normal LA pressures in a dog with endocardiosis, and it indicates a low imminent risk of CHF.…”

“…119,176,182,185,187,190,297,298 Some relevant factors include active myocardial relaxation, ventricular fiber restoring forces (recoil), myocardial stiffness, chamber compliance, pericardial restraint, ventricular interaction, and LA contractility. 45,143,145,151,176,180,181,188,189,191,193,208,225,[302][303][304][305][306][307][308][309][310] The concepts are advanced, and the details are beyond the scope of this introductory chapter. The interplay among these factors is dynamic and complex.…”

“…27,105,[117][118][119][120]135,136,139,148,154,166,171,172,174,175,[202][203][204][205][206]210,217,219,222,229,230,235,241,259,260,262,294,295,306,311,313,[319][320][321][322][323][324][325][326][327][328][329][330][331][332][333]…”