[Responses of aortocoronary bypass graft flow to nitroglycerin, nifedipine and exercise test: a two-dimensional color Doppler echocardiographic study].
To assess the effects of coronary vasodilators and exercise on the blood flow dynamics of aortocoronary bypass grafts (ACBG), two-dimensional Doppler echocardiography was performed in 43 consecutive patients with ACBG of the left coronary artery. Doppler velocity signals of 14 internal mammary artery grafts (IMAG) and three saphenous vein grafts (SVG) were imaged in 15 patients using 5MHZ and 7.5MHZ convex-linear Doppler flow probes. Cross-sectional blood flow velocities and graft internal dimensions were continuously measured before and after the sublingual administration of nitroglycerin (0.3 mg) and nifedipine (20 mg), during isometric handgrip and bicycle ergometer exercise tests. 1. Regurgitant flow in isometric contraction time to early systole was observed in 14 of the 15 patients. Pulsatile diastolic blood flow with mean velocity of 14 +/- 6 cm/sec and volume of 49 +/- 25 ml/min was significantly higher than those in systole (7 +/- 7 cm/sec and 8 +/- 7 ml/min) as observed in IMAG and SVG. IMAG showed smaller vessel dimensions, higher flow velocities and lower flow volumes compared with those of SVG. 2. Nitroglycerin and nifedipine increased blood flow volumes (75 +/- 12%, 79 +/- 11%) and velocities (29 +/- 8%, 28 +/- 8%) due to dilatation of graft vessels (18 +/- 3%, 19 +/- 3%). Nifedipine, in contrast to nitroglycerin, induced sustained increases in graft flows. 3. Isometric handgrip and ergometer bicycle exercise tests increased blood flow volumes (34 +/- 9%, 61 +/- 14%) and velocities (31 +/- 11%, 42 +/- 12%) with elevation of double products (22 +/- 14%, 37 +/- 26%). Ergometer bicycle exercise induced similar responses in systole and diastole, whereas isometric handgrip test induced higher ratios of graft flow volume in systole (67 +/- 25%) compared to those in diastole (28 +/- 9%). In conclusion, two-dimensional color Doppler echocardiography is a promising means for the quantitative analysis of blood flow dynamics, assessments of the variable effects of coronary vasodilators and the physiological responses to exercise tests for the aortocoronary bypass graft flow in the early postoperative state.
Matsumura
M
M
First Department of Surgery, Saitama Medical School.
Kyo
S
S
Takamoto
S
S
Yokote
Y
Y
Omoto
R
R
D000368:Aged; D001783:Blood Flow Velocity / Q000187:drug effects / Q000502:physiology; D001026:Coronary Artery Bypass; D015150:Echocardiography, Doppler; D006801:Humans; D007387:Internal Mammary-Coronary Artery Anastomosis; D008297:Male; D008875:Middle Aged; D009543:Nifedipine / Q000494:pharmacology*; D005996:Nitroglycerin / Q000494:pharmacology*; D005082:Physical Exertion / Q000502:physiology*; D012501:Saphenous Vein / Q000601:surgery
D005996:Nitroglycerin; D009543:Nifedipine