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[Left ventricular diastolic reserve during acute pressure loading in hypertrophic cardiomyopathy and dilated
Y Yokote1, M Okamoto, E Sakura
1First Department of Internal Medicine, Hiroshima University, School of Medicine.
Insights
Diastolic reserve is impaired in hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) patients under acute pressure loading. Echocardiography revealed reduced early diastolic filling capacity in these conditions.
Area of Science:
- Cardiology
- Cardiovascular Physiology
- Echocardiography
Context:
- Assessing left ventricular diastolic function is crucial for understanding heart disease.
- Acute pressure loading is a common physiological stressor that can reveal underlying cardiac dysfunction.
- Hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) are distinct conditions affecting ventricular structure and function.
Purpose:
- To evaluate left ventricular diastolic reserve during acute pressure loading.
- To analyze changes in mitral flow velocity patterns using pulsed Doppler echocardiography.
- To compare diastolic response between HCM, DCM, and control subjects.
Summary:
- Systolic blood pressure was elevated by methoxamine infusion in 11 HCM, 9 DCM, and 11 control subjects.
- Left ventricular dimensions and mitral flow velocity patterns were measured before and after pressure loading.
- Diastolic reserve was found to be impaired in both HCM and DCM, with disturbances potentially reflected in the early diastolic phase.
Impact:
- Findings suggest impaired diastolic reserve in HCM and DCM during acute pressure challenges.
- The study highlights the utility of Doppler echocardiography in assessing diastolic dysfunction.
- Results indicate that early diastolic filling may be a sensitive indicator of diastolic impairment in these cardiomyopathies.
Abstract:
To evaluate left ventricular diastolic reserve during acute pressure loading, changes in mitral flow velocity patterns before and after the elevation of blood pressure were analyzed by pulsed Doppler echocardiography in 11 cases of hypertrophic cardiomyopathy (HCM), nine cases of dilated cardiomyopathy (DCM), and 11 control subjects. Systolic blood pressure was elevated 25% above basal values by methoxamine infusion (0.01 mg/kg/min). Before and after methoxamine, left ventricular dimension and mitral flow velocity pattern were obtained by M-mode and pulsed Doppler echocardiography, respectively. The peak velocity in the rapid filling and atrial contraction phases and time-velocity integrals were measured from the flow pattern. After methoxamine, left ventricular diastolic dimension was significantly increased in all groups, from 43.8 +/- 4.7 mm to 47.4 +/- 4.9 mm in the control subjects, from 43.7 +/- 6.3 mm to 47.2 +/- 6.0 mm in HCM, and from 57.9 +/- 6.4 mm to 60.6 +/- 5.9 mm in DCM. Left ventricular systolic dimension was significantly increased from 48.6 +/- 8.4 mm to 52.8 +/- 8.3 mm in DCM, but not in the control subjects or HCM. The peak velocity in the rapid filling phase was significantly increased from 60 +/- 16 cm/sec to 69 +/- 14 cm/sec in the control subjects and tended to be increased from 44 +/- 13 cm/sec to 52 +/- 12 cm/sec in HCM. The extent of this increase tended to be less in HCM. However, the peak velocity in the rapid filling phase tended to decrease in DCM. There were no consistent trends of changes in the peak velocity in the atrial contraction phase in any groups. The mitral velocity integral increased from 502 Hz-sec to 621 Hz-sec in the controls and from 525 Hz-sec to 613 Hz-sec in HCM, but it did not increase in DCM. These findings suggest that there is impaired diastolic reserve during acute pressure loading in HCM and DCM and that the diastolic disturbance might be reflected in the early diastolic phase, rather than in the late diastolic phase.