Although studies with a sufficient number of minority patients are sparse, those available suggest that black Americans have a higher case fatality from coronary heart disease, but lesser amounts of atherosclerotic coronary artery disease. A possible explanation for this apparent paradox is that myocardial ischemia may be more prevalent with less coronary artery atherosclerosis in black Americans because of comorbid diseases or differences in coronary physiology. This could be secondary to excess hypertension and left ventricular hypertrophy in black Americans but may also be related to intrinsic or acquired differences in coronary artery autoregulation and vasoreactivity leading to depression in coronary blood flow and reserve. The proposed research will study mechanisms of excess coronary ischemia secondary to alterations in autoregulation and arteriolar vasoreactivity in black Americans with hypertension, varying degree of left ventricular hypertrophy and angiographically normal or mildly diseased coronary arteries. The intracoronary Doppler flow velocity guidewire together with quantitative coronary angiography will be used to study changes in coronary blood flow in man secondary to pharmacologic provocateurs known to induce arteriolar vasodilation. White Americans with similar demographic characteristics and equivalent amount of ventricular hypertrophy and coronary disease will be similarly studied in a parallel fashion for comparison. A control group of normal white and black Americans will be studied to detect unexpected intrinsic differences. Both endothelium dependent and independent induction of coronary arteriolar vasodilation will be studied. In 25% of patients with endothelium dependent defects in arteriolar vasodilation, retesting will be performed after intracoronary infusion of L-arginine, the precursor of endothelium dependent relaxing factor. Finally, the possibility of a rightward shift in coronary artery autoregulation in chronic hypertension will be investigated. This finding would necessitate that the lower limit of autoregulation occur at higher diastolic pressures, resulting in a drop-off of coronary perfusion at normal physiologic pressures and ischemia.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL050262-04
Application #
2226397
Study Section
Special Emphasis Panel (ZHL1-CSR-K (01))
Project Start
1992-09-30
Project End
1997-08-31
Budget Start
1995-09-01
Budget End
1996-08-31
Support Year
4
Fiscal Year
1995
Total Cost
Indirect Cost
Name
Albany Medical College
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
City
Albany
State
NY
Country
United States
Zip Code
12208
DeTommasi, Allison; Rogge, Scott; Houghton, Jan Laws (2003) Refractory vasomotor angina in subclinical hyperthyroidism demonstrating focal and segmental coronary vasoconstriction. J Invasive Cardiol 15:289-92
Houghton, Jan Laws; Strogatz, David S; Torosoff, Mikhail T et al. (2003) African Americans with LVH demonstrate depressed sensitivity of the coronary microcirculation to stimulated relaxation. Hypertension 42:269-76
Houghton, Jan L; Philbin, Edward F; Strogatz, David S et al. (2002) The presence of African American race predicts improvement in coronary endothelial function after supplementary L-arginine. J Am Coll Cardiol 39:1314-22
Chander, R; Kuhner, P A; Laws Houghton, J (2001) Endothelial dysfunction and progressive coronary atherosclerosis: sequential invasive studies in a patient with multiple cardiac risk factors. J Invasive Cardiol 13:601-4
Houghton, J L; Cerda, J; Smith, V E (2000) Basal and reserve renal artery blood flow: effect of endothelium-dependent and -independent vasoactive agonists and radiographic contrast medium in two patients. J Invasive Cardiol 12:211-5
Houghton, J L; Pearson, T A; Reed, R G et al. (2000) Cholesterol lowering with pravastatin improves resistance artery endothelial function: report of six subjects with normal coronary arteriograms. Chest 118:756-60
Houghton, J L; Davison, C A; Kuhner, P A et al. (1998) Heterogeneous vasomotor responses of coronary conduit and resistance vessels in hypertension. J Am Coll Cardiol 31:374-82
Houghton, J L; Smith, V E; Strogatz, D S et al. (1997) Effect of African-American race and hypertensive left ventricular hypertrophy on coronary vascular reactivity and endothelial function. Hypertension 29:706-14
Houghton, J L; Carr, A A; Strogatz, D S et al. (1997) Coronary vasomotor reactivity among normotensive African and white American subjects with chest pain. Am J Med 102:245-51
Houghton, J L; Smith, V E; Breisblatt, W M et al. (1996) Coronary vasomotor function in a normotensive, nondiabetic referral population with normal coronary arteriograms. Am J Cardiol 77:1241-4

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