Lowering of blood pressure and coronary blood flow in isolated systolic hypertension.
BACKGROUND
In essential hypertension, the lower limit of autoregulation of coronary flow shifts to higher perfusion and the hypertensive ventricle is at a higher than normal risk of ischemia, and less able to tolerate acute reduction of coronary perfusion pressure. Little is known about pattern of coronary flow in isolated systolic hypertension, a pathologic condition in which the elevated systolic blood pressure is associated with a lower than normal vascular compliance and normal or slightly greater than normal mean arterial pressure and vascular resistance.


OBJECTIVE
To evaluate the effects of rapid normalization of blood pressure on coronary blood flow in isolated systolic hypertension.


METHODS
We subjected 20 patients with isolated systolic hypertension to intraoperative hemodynamic and transesophageal echocardiographic monitoring during peripheral vascular surgery. Coronary flow velocity integrals and diameters in the left anterior descending coronary artery were evaluated under baseline conditions and after normalization of blood pressure, which occurred spontaneously during anesthesia (10 cases; group 1A) or was induced by infusion of nitrate (10 cases, group 1B).


RESULTS
After normalization of systolic blood pressure integrals decreased significantly only for patients in group 1A; percentage changes of diameter were significantly greater for patients in group 1B. Therefore, coronary blood flow after normalization of systolic blood pressure increased for patients in group 1B (by 28+/-25%) and decreased for patients in group 1A (by 30+/-21%). Changes in integrals were inversely related to those in diameter (r= -0.72, P < 0.001); for patients in group 1A changes in coronary perfusion pressure and diameter were related to those of integrals (r= 0.94; P < 0.0005).


CONCLUSIONS
In isolated systolic hypertension, despite there being similar changes of the systolic blood pressure, administration of nitrates caused a marked increase of coronary flow through direct effects on coronary circulation, whereas spontaneous normotension was associated with a significant reduction of coronary flow.
Tamborini
G
G
Centro Cardiologico, Fondazione Monzino, IRCCS, Centro di Studio per le Ricerche Cardiovascolari del CNR, Milan, Italy. gtamborini@cardiologicomonzino.it
Maltagliati
A
A
Trupiano
L
L
Berna
G
G
Sisillo
E
E
Salvi
L
L
Pepi
M
M
D000368:Aged; D018686:Anesthetics, Intravenous; D001794:Blood Pressure / Q000187:drug effects*; D003326:Coronary Circulation / Q000187:drug effects*; D003975:Diazepam; D004452:Echocardiography; D017548:Echocardiography, Transesophageal; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D005996:Nitroglycerin / Q000627:therapeutic use; D013599:Systole / Q000187:drug effects; D014665:Vasodilator Agents / Q000627:therapeutic use
D018686:Anesthetics, Intravenous; D014665:Vasodilator Agents; D005996:Nitroglycerin; D003975:Diazepam