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Relation between electrocardiographic repolarisation changes and mechanical events in left ventricular hypertrophy
Insights
Electrocardiographic "strain" in left ventricular hypertrophy is linked to impaired early diastolic relaxation, not systolic dysfunction. Abnormal electrical recovery in these patients may occur independently of other factors.
Area of Science:
- Cardiology
- Physiology
Background:
- Left ventricular hypertrophy (LVH) can affect ventricular function.
- Electrocardiographic (ECG)
- strain
- patterns are observed in some LVH patients.
Purpose of the Study:
- To investigate the relationship between ECG
- strain
- and ventricular function in patients with LVH.
- To differentiate electrical abnormalities from mechanical dysfunction.
Main Methods:
- Utilized digitized M-mode echocardiography and 12-lead ECGs.
- Studied 64 patients with pressure overload LVH, 21 with hypertrophic cardiomyopathy, and 14 athletes.
Main Results:
- Patients with ECG
- strain
- exhibited prolonged diastolic intervals and reduced early diastolic wall thinning.
- Systolic function (fractional shortening, peak velocity of circumferential fibre shortening) was normal in both strain and non-strain groups.
- Athletes showed shorter electromechanical systole with synchronous T wave termination and minimum cavity dimension.
Conclusions:
- Abnormal electrical recovery in LVH is closely associated with impaired early diastolic relaxation.
- This impaired relaxation can be dissociated from systolic function, cavity dimension, and increased myocardial mass.
- The normal relationship between electrical and mechanical systole is maintained even with reversed repolarization polarity.
Abstract:
The relation between ventricular function and the presence of electrocardiographic "strain" in patients with left ventricular hypertrophy was examined using digitised M mode echocardiography and 12 lead electrocardiograms in 64 patients with pressure overload, 21 with hypertrophic cardiomyopathy, and 14 athletes. Although all had increased left ventricular mass, those with strain had a prolonged interval from minimum cavity dimension to mitral valve opening and a reduced rate of early diastolic posterior wall thinning and dimension increase compared with those with normal ST segments and T waves. Both groups had normal systolic function (fractional shortening and peak velocity of circumferential fibre shortening), and the time between the termination of the T wave and minimum dimension was similar. In athletes, however, electromechanical systole was shorter than normal, and the end of the T wave and minimum cavity dimension were synchronous. It is concluded that abnormal electrical recovery in left ventricular hypertrophy is closely related to impaired early relaxation and may be dissociated from impaired systolic function, cavity dimension, interventricular conduction delay, and the presence of increased mass alone. The normal relation between electrical and mechanical systole is preserved even when the polarity of repolarisation is reversed.