Timing of Left Heart Base Descent in Dogs With Dilated Cardiomyopathy and Normal Dogs

Abstract

The identification and assessment of myocardial failure in canine idiopathic dilated cardiomyopathy (DCM) is achieved using a variety of two-dimensional and Doppler echocardiographic techniques. More recently, the availability of tissue Doppler imaging (TDI) has raised the potential for development of new ways of more accurately identifying a disease phenotype. Nevertheless, TDI has not been universally adapted to veterinary clinical cardiology primarily because of the lack of information on its utility in diagnosis. We assessed the application of timing of left heart base descent using TDI in the identification of differences between DCM and normal dogs. The times from the onset of the QRS complex on a simultaneously recorded electrocardiograph to the onset (Q--S'), peak (Q--peak S'), and end (Q--end S') of the systolic velocity peak were measured in the interventricular septum (IVS) and the left ventricular free wall. The duration of S' was also calculated. The Q--S' (FW), Q--end S' (FW), and duration S' (FW) were correlated with ejection fraction in the diseased group (P < 0.05). In addition, Q--S', Q--peak S', Q--end S', and the peak S' velocity were prolonged in the diseased dogs at both the free wall and in the IVS (P < 0.01). The duration of S' was unaffected by disease status. These findings provide insight into the electromechanical uncoupling that occurs in canine DCM and identifies new TDI parameters that can be added to the range of Doppler and echocardiographic parameters used for detecting myocardial failure in the dog.

Global Left Ventricular Systolic Function Assessment

“…They observed that the intervals Q-beginning of S′, Q-end of S′ were extended and the maximum velocity of S′ was reduced in dogs with dilated cardiomyopathy. The S′ duration was not affected by the systolic dysfunction [43]. …”

“…These are the left heart base descent time intervals [43]. To obtain these time intervals, the S′ wave of the base of the interventricular septum or left ventricular free wall must be recorded using TDI.…”

Tissue Doppler and Strain Imaging in Dogs with Myxomatous Mitral Valve Disease in Different Stages of Congestive Heart Failure

“…Patients with intraventricular dyssynchrony were, independent of QRS width and EF, at significantly higher risk of cardiac events, 48,49 and LV systolic and diastolic mechanical dyssynchrony is reported to be common in patients with CHF 50 . Systolic velocity time‐to‐peak was longer in the lateral wall compared with that of IVS in dogs with DCM 9 …”

“…2 Tissue Doppler imaging (TDI) has been extensively evaluated in healthy dogs and in dogs with different heart diseases. [7][8][9][10][11][12][13] This relatively new technique allows quantitative assessment of segmental and global myocardial radial and longitudinal motion in systole and diastole, as well as accurate timing of events in relation to the QRS complexes on ECG recordings. TDI variables have been reported in dogs with MMVD and concomitant pulmonary hypertension.…”

Echocardiography

“…115,192,263,307,311,312,[468][469][470][471][472] Atrioventricular valve insufficiency is usually present (see Figure 8-52; Video 8-36, B to D), although the regurgitation is often mild when compared to dogs with primary valvular disease or to cats with diuretic therapy, especially if a precipitating cause is identified and reversible. 115,192,263,307,311,312,[468][469][470][471][472] Atrioventricular valve insufficiency is usually present (see Figure 8-52; Video 8-36, B to D), although the regurgitation is often mild when compared to dogs with primary valvular disease or to cats with diuretic therapy, especially if a precipitating cause is identified and reversible.…”