Non-invasive assessment of left ventricular relaxation property using color M-mode-derived intraventricular pressure
K Matsuura1, M B T Bach2, K Takahashi3
1Department of Veterinary Surgery, Tokyo University of Agriculture and Technology, Japan.
Insights
Intraventricular pressure gradients (IVPGs) in cats increase with heart rate and shorter isovolumic relaxation times, offering a new non-invasive method to assess feline heart function.
Area of Science:
- Veterinary Cardiology
- Cardiac Physiology
- Diagnostic Imaging
Background:
- Diastolic dysfunction is an early indicator of feline hypertrophic cardiomyopathy (HCM).
- The diastolic intraventricular pressure gradient (IVPG) facilitates left ventricular filling.
- Assessing IVPG is crucial for understanding feline diastolic function.
Purpose of the Study:
- Evaluate color Doppler M-mode for non-invasive IVPG calculation in cats.
- Determine normal IVPG ranges in healthy cats.
- Investigate the influence of heart rate and left ventricular function on IVPG.
Main Methods:
- Prospective cross-sectional study involving 106 healthy cats.
- Quantitative analysis of color Doppler M-mode images to estimate total and segmental IVPGs.
- Non-invasive assessment of left ventricular relaxation properties.
Main Results:
- Established normal ranges for total (0.76 mmHg), basal (0.34 mmHg), and mid-apical (0.42 mmHg) IVPGs.
- IVPGs increased with heart rate (HR) and shorter isovolumic relaxation time (IVRT).
- Increased IVPG correlated with increased mitral inflow velocity.
Conclusions:
- Feline IVPGs are influenced by HR and IVRT, suggesting a normal physiologic response.
- Color Doppler M-mode offers a viable non-invasive method for IVPG assessment in cats.
- Further research is needed to explore segmental IVPG changes in feline HCM.
Introduction:
Diastolic dysfunction is an early clinical feature of feline hypertrophic cardiomyopathy (HCM). The left ventricular filling in early diastole is facilitated by the diastolic intraventricular pressure gradient (IVPG). The study objectives were to evaluate color Doppler M-mode-derived IVPG calculation in cats as a non-invasive assessment of the left ventricular relaxation property to determine the normal ranges of peak IVPG in cats and investigate the influence of left ventricular function and heart rate (HR).
Animals:
One hundred and six client-owned apparently healthy cats.
Methods:
Prospective cross-sectional study. Quantitative analysis of color Doppler M-mode images was used to estimate total and segmental IVPGs non-invasively.
Results:
The total IVPG was 0.76 mmHg (95% reference interval (RI): 0.28-1.29 mmHg), the basal IVPG 0.34 mmHg (95% RI: 0.07-0.63 mmHg), and the mid-apical IVPG 0.42 mmHg (95% RI: 0.15-0.71 mmHg). Total and segmental IVPG increased with HR (P < 0.003), while segmental percent IVPG was HR independent. A short isovolumic relaxation time (IVRT) and a high mitral annular velocity in early diastole were associated with an increase in total IVPG (P = 0.008 and P = 0.009, respectively) adjusted for HR. An increase in IVPG was associated with an increase in mitral inflow velocity (P < 0.001).
Conclusions:
Feline IVPGs increase with HR and a short IVRT, which was believed to be a normal physiologic adrenergic response associated with an increased sympathetic tone. Future studies of segmental IVPG changes in feline HCM are needed to evaluate the clinical applicability of color Doppler M-mode estimated IVPGs in feline cardiology.
