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Effect of left ventricular hypertrophy secondary to systemic hypertension on left coronary artery flow dynamics
Insights
Hypertension-induced left ventricular hypertrophy impairs coronary blood flow, causing delayed diastolic inflow. This delay is linked to reduced coronary flow reserve in hypertensive patients.
Area of Science:
- Cardiology
- Physiology
- Medical Imaging
Background:
- Systemic hypertension frequently leads to left ventricular hypertrophy (LVH).
- The impact of hypertensive LVH on coronary blood flow dynamics is not fully understood.
- Phasic blood velocity patterns in coronary arteries are crucial for assessing myocardial perfusion.
Purpose of the Study:
- To characterize the phasic blood velocity patterns in the left anterior descending coronary artery (LAD) in patients with LVH secondary to systemic hypertension.
- To investigate the underlying causes of observed velocity pattern alterations.
- To determine the relationship between these patterns and coronary flow reserve.
Main Methods:
- Doppler catheter measurements of LAD blood velocities in 23 hypertensive patients with LVH and 13 controls.
- Patients with LVH had significantly elevated systolic/diastolic pressures (181/100 mm Hg).
- Coronary arteriograms were normal in all participants.
Main Results:
- Patients with hypertensive LVH exhibited delayed early diastolic inflow in the LAD.
- The diastolic rise time (TDR) of coronary flow was significantly prolonged in hypertensive LVH patients (145 ms vs. 66 ms).
- Prolonged TDR correlated with the degree of LVH and peak systolic pressure, and was associated with decreased coronary flow reserve.
Conclusions:
- Impaired early diastolic coronary arterial inflow is a key feature of pressure-overloaded LVH.
- Delayed diastolic inflow is associated with systolic vascular compression and impaired left ventricular relaxation.
- This delayed inflow is a significant factor contributing to reduced coronary flow reserve in hypertensive LVH.
Study Objective:
The aim was to clarify the characteristics of the phasic blood velocity pattern and their possible causes in left ventricular hypertrophy secondary to systemic hypertension.
Design:
Measurements of blood velocities in the left anterior descending coronary artery were made with a 20 MHz Doppler catheter with a top mounted annular crystal. All patients had normal coronary arteriograms.
Patients:
23 hypertensive patients [systolic/diastolic pressure: 181(SD 15)/100(4) mm Hg)] with left ventricular hypertrophy, and 13 atypical chest pain patients without left ventricular hypertrophy or any abnormal haemodynamic findings (normal controls) entered the study.
Measurements And Main Results:
The left anterior descending coronary artery blood velocity waveform in pressure overloaded left ventricular hypertrophy was characterised by delayed early diastolic inflow. The diastolic rise time of coronary flow (TDR), ie, the time from the beginning of diastole to peak velocity, was higher in patients with hypertensive left ventricular hypertrophy than in normal controls, at 145(56) v 66(15) ms, p less than 0.001. In patients with hypertensive left ventricular hypertrophy, TDR correlated well with the degree of hypertrophy (r = 0.83, p less than 0.01) and also with peak left ventricular systolic pressure (r = 0.62, p less than 0.01). The coronary flow reserve, calculated from the ratio of the diastolic mean velocity after intracoronary injection of papaverine to the resting flow velocity, decreased with prolongation of TDR (r = 0.58, p less than 0.02).
Conclusions:
(1) Impairment of early diastolic coronary arterial inflow is the most remarkable characteristic in pressure overloaded left ventricular hypertrophy; (2) preceding systolic vascular compression and impaired left ventricular relaxation correlate with the delayed early diastolic inflow; (3) the delayed inflow is an important possible cause of the decreased coronary flow reserve in the hypertensive left ventricular hypertrophy.