Background. Patients with essential arterial hypertension (EH) demonstrated abnormal vasodilator capacity either during increase in cardiac metabolic demand or during pharmacological vasodilatation. Morpho-functional damage to coronary microcirculation has been advocated as one of the major causes of impaired coronary flow reserve in this disease. Methods and results. To evaluate the role of microvascular impairment on regional myocardial blood flow (MBF) distribution, 16 patients with EH were evaluated by dynamic positron emission tomography (PET) and 13N-ammonia at rest and during atrial pacing (AP); their findings were compared with 8 normal subjects. In a subgroup of 10 patients the study was repeated after 6 months of antihypertensive therapy with calcium-channel blockers or angiotensin-converting enzyme inhibitors as part of a randomized, single blind pharmacological trial. The PET evaluation was performed after that therapy was discontinued for a week, to allow recovery of blood pressure at levels comparable with the pre-treatment study. All patients had normal coronary arteries, 10 had left ventricular hypertrophy by echocardiographic criteria, while 6 did not. Baseline mean MBF in patients with EH was not significantly different from control group (0.97 ± 2.7 ml/min/g and 0.94 ± 1, respectively, ns), significantly increased to 1.69 ± 42 during AP (p < .01); however, mean flow during AP was significantly lower than in controls (2.15 ± 73 ml/min/g; p < .01). MBF response to AP was similarly depressed in both hypertrophic and non-hypertrophic patients. Antihypertensive therapy in 10 patients significantly improved the MBF response to pacing tachycardia (1.6 ± 39 ml/min/g pre-treatment vs 2.06 ± 65 ml/min/g post treatment, p < .05), in absence of changes in left ventricular mass or in metabolic demand. Conclusions. An obvious impairment of MBF during pacing tachycardia was observed in EH patients with normal coronary arteries, apparently unrelated to the presence of myocardial hypertrophy. Antihypertensive therapy with calcium-channel blockers or angiotensin-converting enzyme inhibitors was able to normalize MBF values during tachycardia. PET allowed identification of early abnormalities in coronary microvascular function.
|Autori:||Parodi O; Neglia D; Palombo C; Sambuceti G.|
|Titolo:||Regional myocardial blood flow during pacing tachycardia in patients with arterial hypertension: The effect of therapy|
|Anno del prodotto:||1991|
|Appare nelle tipologie:||1.1 Articolo in rivista|