Background-Sodium nitroprusside is one of several agents considered effective for treating the no-reflow phenomenon during acute coronary interventions. However, the coronary hyperemic dose responses and systemic hemodynamic effects of intracoronary nitroprusside have yet to be determined in humans. The purpose of this study was to compare the hyperemic and hemodynamic responses of intracoronary nitroprusside to intracoronary adenosine in patients during cardiac catheterization with angiographically normal anterior descending arteries. Methods and Results-In 21 patients, coronary blood flow velocity (0.014-inch Doppler flow wire), heart rate, and blood pressure were measured in unobstructed left anterior descending coronary arteries at rest, after intracoronary adenosine (30-to 50-g boluses), and after 3 serial doses (0.3-, 0.6-, and 0.9-g/kg boluses) of intracoronary nitroprusside. Coronary reserve was calculated as hyperemia/basal coronary flow velocity. In an additional 9 patients with intermediate stenoses (53Ϯ7%), 14 fractional flow reserve (FFR) measurements (using 0.014-inch pressure wire) were performed with both intracoronary adenosine and nitroprusside (0.6 g/kg). Intracoronary nitroprusside produced equivalent coronary hyperemia with a longer duration (Ϸ25%) compared with intracoronary adenosine. Intracoronary nitroprusside (0.9 g/kg) decreased systolic blood pressure by Ͻ20%, with minimal change in heart rate, whereas intracoronary adenosine had no effect on these parameters. FFR measurements with intracoronary nitroprusside were identical to those obtained with intracoronary adenosine (rϭ0.97). Conclusions-Compared with adenosine, intracoronary nitroprusside produces an equivalent but more prolonged coronary hyperemic response in normal coronary arteries. Intracoronary nitroprusside, in doses commonly used for the treatment of the no-reflow phenomenon, can produce sustained coronary hyperemia without detrimental systemic hemodynamics. On the basis of FFR measurements compared with adenosine, sodium nitroprusside also appears to be a suitable hyperemic stimulus for coronary physiological measurements.

In some patients, myocardial ischemia after coronary artery bypass graft surgery has been attributed to a coronary steal phenomenon through a thoracic side branch originating from the left internal mammary artery (LIMA), even in the absence of subclavian or LIMA stenosis. To demonstrate that coronary flow through the LIMA is unchanged by occlusion of a LIMA side branch, we examined LIMA coronary flow velocity measurements (0.014" Doppler flow wire) in three patients at rest, during adenosine hyperemia, and again during hyperemia induced by left arm exercise before and again after the balloon occlusion of the thoracic side branch. For the three patients, no significant changes in resting or hyperemic flow were noted due to side-branch occlusion. Before side-branch occlusion, pharmacologic intra-arterial (adenosine) coronary flow reserve (hyperemic-to-basal flow velocity ratio) was 2.6, 1.5, and 3.2 and exercise flow reserve was 2.1, 1.3, and 1.2, respectively. After side-branch occlusion, pharmacologic coronary flow reserve was 2.5, 1.8, and 2.7 with exercise flow reserve of 1.8, 1.1, and 1.3, respectively. Under most ordinary circumstances, thoracic side-branch steal does not exist and that side-branch occlusion does not alter LIMA flow at rest or during pharmacologic or exercise-induced hyperemia. These data further suggest that a demonstration of the physiologic value of side-branch occlusion should precede surgical or percutaneous interruption of the thoracic artery in such patients.

Coronary angiography using 4 Fr catheters may reduce access site complications, promote better utilization of outpatient facilities, but at a cost of suboptimal image quality. To determine whether 4 Fr diagnostic angiography with power injection (Acist, Minneapolis, MN) was equivalent to 6 Fr manual technique, 101 unselected patients were randomized to transfemoral coronary angiography with 4 or 6 Fr catheters. Procedural characteristics, angiographic quality scores, and results of 90 min ambulation were analyzed. Coronary angiographic quality scores using 4 Fr and 6 Fr catheters were equivalent (left coronary artery 4.73 +/- 0.6 vs. 4.80 +/- 0.65, P = 0.28; right coronary artery 4.98 +/- 90.13 vs. 4.97 +/- 0.16, P = 0.48). However, 4 Fr left ventriculographic image score was lower (4.53 +/- 0.68 vs. 4.83 +/- 0.42, P = 0.0002), attributed, in part, to a smaller injected contrast volume (32 +/- 11 vs. 37 +/- 4 mL, P = 0.001). The total study contrast volume was significantly less in the 4 Fr group (119 +/- 35 vs. 159 +/- 52 mL, P = 0.001). Complications related to early ambulation at 90 min were similar and minimal in both groups. Compared to 6 Fr manual contrast injection technique, diagnostic angiography through 4 Fr catheters with power contrast injection resulted in equivalent coronary angiographic image quality, slightly reduced but diagnostic left ventricular image quality, and significantly less contrast volume. Four Fr angiography facilitates early ambulation without compromising safety and image quality.

Compared with 6F catheters, diagnostic coronary angiographic and ventriculographic images with 4F catheters can be obtained with equivalent results using less radiographic contrast volume. Whether 4F coronary angiography would be superior using a power-assisted, operator-controlled technique compared with manual technique is unknown. To determine whether 4F coronary angiography using operator-controlled power injection (Acist, Minneapolis, MN) was equivalent or superior to the 4F manual technique, 96 unselected patients undergoing transfemoral coronary angiography were randomized to 4F catheter using a power injection or manual technique. Procedural characteristics and angiographic quality scores were analyzed. Comparing the 4F manual with the 4F power-injection technique, coronary angiographic quality scores were equivalent (left coronary artery 4.7 +/- 0.5 vs. 4.7 +/- 0.6, P = 0.99; right coronary artery 4.94 +/- 0.2 vs. 4.88 +/- 0.1, P = 0.21). Left ventriculography scores were lower in 4F Acist with similar contrast volumes. The total study contrast volume was significantly less in the 4F Acist group (119 +/- 35 vs. 149 +/- 49 ml, P = 0.001). Compared with the 4F manual contrast injection technique, diagnostic angiography through 4F catheters with power contrast injection resulted in equivalent coronary angiographic image quality with significantly less radiographic contrast volume.

Fractional flow reserve (FFR) determinations have been demonstrated to be largely independent of changes in systemic hemodynamic changes. Herein, we describe a case of obstructive sleep apnea cyclically altering FFR measurements from normal to abnormal in a patient with an intermediately severe coronary narrowing following treatment for an acute coronary syndrome. To eliminate uncertainty, FFR measurements should be made if possible during suspended respiration.