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Myocardial ischemia and ventricular arrhythmias in relation to left ventricular mass and resistance artery structure
I Sihm1, P Søgaard, A P Schroeder
1Department of Medicine and Cardiology, Aarhus University Hospital, Denmark.
Insights
Essential hypertension patients with left ventricular hypertrophy and permanent ST depression show increased peripheral vessel media:lumen ratio. This indicates similar hypertensive structural changes in myocardial resistance arteries.
Area of Science:
- Cardiology
- Vascular Biology
- Hypertension Research
Background:
- Essential hypertension is a major risk factor for cardiovascular disease.
- Left ventricular hypertrophy (LVH) and ventricular arrhythmias are common complications.
- The structural changes in peripheral and myocardial resistance arteries in hypertensive patients are not fully understood.
Purpose of the Study:
- To investigate the relationship between hypertensive structural changes in peripheral resistance arteries and cardiac alterations.
- To assess the media:lumen ratio in peripheral vessels in relation to left ventricular mass and arrhythmias.
Main Methods:
- Study included 83 essential hypertension patients (mean age 47 years).
- Measured media:lumen ratio of small resistance arteries using isometric myography.
- Assessed left ventricular mass (LVM) by echocardiography and ventricular arrhythmias by 48-h ambulatory ECG.
Main Results:
- 67% of patients had LVH; 75% showed ST depression; 45% had ventricular arrhythmias.
- Permanent ST depression correlated with greater LVM and more frequent arrhythmias.
- Patients with LVH and permanent ST depression had a significantly greater media:lumen ratio (11.6 +/- 2.9) compared to those with LVH but without permanent ST depression (9.8 +/- 2.0).
Conclusions:
- Hypertensive structural changes in peripheral resistance arteries may mirror those in myocardial resistance arteries.
- Permanent ST depression is associated with increased cardiac remodeling and arrhythmias in hypertensive patients.
- Findings suggest a link between systemic vascular changes and cardiac structural alterations in essential hypertension.
Abstract:
The study comprised 83 patients, mean (+/-SD) age 47 +/- 8 years, with essential hypertension. Systolic and diastolic blood pressure at inclusion were 171 +/- 16 and 110 +/- 7 mm Hg, respectively. Two small resistance arteries were dissected from a subcutaneous gluteal biopsy and mounted in an isometric small vessel myograph for measurement of the media:lumen ratio. Left ventricular mass (LVM) was estimated by echocardiography, and the occurrence of ventricular arrhythmias was assessed by ambulatory ECG for 48 h. Left ventricular hypertrophy (LVH) occurred in 67% of the patients. Systolic function was generally unimpaired. ST depression was found in 75%, and ventricular arrhythmias in 45%. Twenty-two patients had permanent ST depression, and they had also greater LVM and more frequent ventricular arrhythmias than those without permanent ST depression. The area under the ST trend curve of all significant ST depressions was correlated to the LVM (r = 0.42, p < 0.001). Patients with arrhythmias had significantly greater area under the ST trend curve of all significant ST depressions than patients without arrhythmias (p < 0.05). In patients with LVH and permanent ST depression, the media:lumen ratio of the peripheral vessels was greater than that of patients with LVH but without permanent ST depression (11.6 +/- 2.9 vs. 9.8 +/- 2.0, p < 0.01). This suggests that hypertensive structural changes similar to those observed in peripheral vessels might occur in the walls of myocardial resistance arteries.