Coronary vasomotor response to phenylephrine in heart transplant patients.

BACKGROUND: Coronary vasomotor responses to sympathetic stimulation vary with endothelial-layer integrity or presence of atherosclerosis. Our study objective was to assess the effects of phenylephrine-induced alpha-adrenergic stimulation on coronary vasomotion in heart transplant recipients with and without graft atherosclerosis. METHODS: Intracoronary phenylephrine (alpha(1)-selective agonist) was injected in 6 control subjects, 9 recipients with angiographically normal coronary arteries and 8 recipients with mild or moderate atherosclerosis. Coronary flow velocity was measured using a Doppler guide-wire. The diameters of 3 epicardial segments of the left coronary artery and coronary blood flow and resistance were assessed at baseline, after infusion of increasing acetylcholine doses (10(-7) and 10(-6) mol/liter) and after phenylephrine (150- to 200-microg bolus). Systemic and coronary hemodynamic parameters were measured immediately after acetylcholine and 1, 3, 5, 7, 10 and 15 minutes after phenylephrine. RESULTS: Phenylephrine induced similar significant increases in rate pressure product in the 3 groups. Acetylcholine induced epicardial vasodilation in controls and vasoconstriction in transplant recipients. Phenylephrine induced epicardial vasodilation in controls and in angiographically normal recipients; subsequent vasoconstriction occurred in this last group. In the recipients with angiographic abnormalities, sustained vasoconstriction occurred. At peak phenylephrine effect, coronary blood flow (CBF) increased significantly (p < 0.001 vs baseline) in all 3 groups. Coronary resistance decreased in the 3 groups but the decrease was smaller in the recipients with angiographic abnormalities (p < 0.05 vs controls). CONCLUSIONS: In heart transplant patients, graft atherosclerosis unmasks the direct coronary vasoconstricting effects of pharmacologic alpha-adrenergic stimulation.

Transulnar versus transradial artery approach for coronary angioplasty: the PCVI-CUBA study.

OBJECTIVES: To compare in terms of efficacy and safety the transulnar to the transradial approach for coronary angiography and angioplasty. BACKGROUND: Opposite to the transradial approach, which is now widely used in catheterization laboratories worldwide, the ulnar artery approach is rarely used for cardiac catheterization. METHODS: Diagnostic coronarography, followed or not by angioplasty, was performed by transulnar or transradial approach, chosen at random. A positive (normal) direct or reverse Allen's test was required before tempting the radial or the ulnar approach, respectively. MACE were recorded till 1-month follow-up. Doppler ultrasound assessment of the forearm vessels was scheduled for all the angioplastied patients. RESULTS: Successful access was obtained in 93.1% of patients in the ulnar group (n = 216), and in 95.5% of patients in the radial group (n = 215), P = NS. One hundred and three and 105 angioplasty procedures were performed in 94 and 95 patients in ulnar and radial group, with success in 95.2% and 96.2% of procedures in ulnar and radial group, respectively (P = NS). Freedom from MACE at 1-month follow-up was observed in 93 patients in both groups (97.8% for ulnar group and 95.8% for radial group), P = NS. Asymptomatic access site artery occlusion occurred in 5.7% of patients after transulnar and in 4.7% of patients after transradial angioplasty. A big forearm hematoma, and a little A-V fistula were observed, each in one patient, in the ulnar group. CONCLUSION: The transulnar approach for diagnostic and therapeutic coronary interventions is a safe and effective alternative to the transradial approach, as both techniques share a high success rate and an extremely low incidence of entry site complications. The transulnar approach has the potential to spare injury to the radial artery in anticipation of its use as a coronary bypass conduit.

Coronary vasomotor response to the selective B1-kinin-receptor agonist Des-Arg9-bradykinin in humans.

OBJECTIVES: The aim of the present study was to assess the effects of selective B1-receptor stimulation with des-Arg9-bradykinin on coronary vasomotion in transplanted and non-transplanted patients. BACKGROUND: Bradykinin B1-receptors have been identified on endothelial and smooth muscle cells in human coronary arteries in vitro; however, their physiologic role in the coronary circulation is unknown. METHODS: Twelve heart transplant patients were compared with 10 control subjects at 3.2 +/- 2.2 months after surgery. Coronary flow velocity was measured using guide-wire Doppler. The diameter of 3 epicardial segments of the left coronary artery and coronary blood flow were assessed at baseline, immediately after infusions of increasing doses of des-arginine(Arg9)-bradykinin at estimated coronary blood concentrations of 5.4 x 10(-9), 5.4 x 10(-8), 5.4 x 10(-7) and 1.6 x 10(-6) mol/liter, and of acetylcholine at 10(-8), 10(-7) and 10(-6) mol/liter). RESULTS: Des-Arg9-bradykinin induced a similar decrease in all measured epicardial diameters in both groups and no change in coronary blood flow. Vasoconstriction was significant only at the 2 highest concentrations: -6 +/- 9% (p < 0.01) and -7 +/- 11% (p < 0.01) in control subjects, and -8 +/- 8% (p < 0.001) and -9 +/- 11% (p < 0.001) in heart transplant patients. Acetylcholine induced significant epicardial vasodilation in control subjects and vasoconstriction in transplant patients. The presence of allograft rejection did not modify the responses to des-Arg9-bradykinin with regard to both conductance and resistance vessels. CONCLUSIONS: Kinin B1-receptors exist and can be stimulated in humans. The vasoconstrictive action on epicardial coronary arteries of des-Arg(9)-bradykinin in humans argues for a predominant action of B1-receptor stimulation at the level of smooth muscle cells.

Percutaneous transulnar artery approach for diagnostic and therapeutic coronary intervention.

While the transradial approach is now a well-established alternative to the conventional femoral approach for cardiac catheterization, the ulnar artery is rarely used. The objective of this prospective study was to evaluate the feasibility and safety of transulnar catheterization for routine diagnostic and therapeutic coronary interventions. Among 210 consecutive patients referred for diagnostic coronary angiography and or angioplasty and screened for appropriateness of the ulnar approach, 172 (172 of 210, 82%) underwent attempted ulnar artery catheterization, which was successful in 158 (158 of 172, 91%). The 173 procedures successfully performed via the ulnar approach included 122 diagnostic coronary angiographies, 38 coronary angiographies followed by angioplasty, and 13 elective angioplasties. Access site complications consisted of one case each of silent ulnar artery thrombosis, pseudoaneurysm, and hematoma due to ulnar artery wall rupture during an unsuccessful catheterization attempt. No cardiac or systemic complications were recorded. The transulnar approach appears feasible and safe for routine coronary diagnostic and therapeutic interventions.

Early changes in coronary flow physiology after balloon angioplasty or stenting: a 24-hour Doppler flow velocity study.

To evaluate early changes in myocardial microcirculation after balloon or stent coronary angioplasty, we studied 57 patients undergoing coronary angioplasty with a Doppler-tipped guidewire, with (n = 26) or without stenting. Postprocedural quantitative coronary angiography and coronary flow velocity were measured after 10 min and 24 hr. As compared to stenting, no stenting was associated with a higher postprocedural stenosis rate (21% +/- 13% vs. 12% +/- 10%; P < 0.05), smaller coronary velocity reserve (CVR; 2.2 +/- 0.4 vs. 2.5 +/- 0.7; P = 0.04), and smaller relative CVR (0.8 +/- 0.2 vs. 1.1 +/- 0.3; P = 0.001). At 24 hr, CVR and relative CVR in the unstented group increased to the level in the stented group, mainly because of a decrease in basal average peak velocity (APV). Overall, there was a significant negative linear relation between CVR and APV variations during the 24-hr period. In the subgroups with persistent abnormalities, CVR variation was closely related to the basal APV/reference APV ratio. In conclusion, coronary reserve normalization can occur within 24 hr after coronary angioplasty and is closely dependent on postangioplasty APV. Myocardial distal resistances should be considered when interpreting postangioplasty CVR.

Empirical estimates of mean aortic pressure: advantages, drawbacks and implications for pressure redundancy.

Mean arterial pressure (MAP) is estimated at the brachial artery level by adding a fraction of pulse pressure (form factor; =0.33) to diastolic pressure. We tested the hypothesis that a fixed form factor can also be used at the aortic root level. We recorded systolic aortic pressure (SAP) and diastolic aortic pressure (DAP), and we calculated aortic pulse pressure (PP) and the time-averaged MAP in the aorta of resting adults (n=73; age 43+/-14 years). Wave reflection was quantified using the augmentation index. The aortic form factor (range 0.35-0.53) decreased with age, MAP, PP and augmentation index (each P<0.001). The mean form factor value (0.45) gave a reasonable estimation of MAP (MAP=DAP+0.45PP; bias=0+/-2 mmHg), and the bias increased with MAP (P<0.001). An alternative formula (MAP=DAP+PP/3+5 mmHg) gave a more precise estimation (bias=0+/-1 mmHg), and the bias was not related to MAP. This latter formula was consistent with the previously reported mean pulse wave amplification of 15 mmHg, and with unchanged MAP and diastolic pressure from aorta to periphery. Multiple linear regression showed that 99% of the variability of MAP was explained by the combined influence of DAP and SAP, thus confirming major pressure redundancy. Results were obtained irrespective of whether the marked differences in heart period and extent of wave reflection between subjects were taken into account. In conclusion, the aortic form factor was strongly influenced by age, aortic pressure and wave reflection. An empirical formula (MAP=DAP+PP/3+5 mmHg) that is consistent with mechanical principles in the arterial system gave a more precise estimate of MAP in the aorta of resting humans. Only two distinct pressure-powered functions were carried out in the (SAP, DAP, MAP, PP) four-pressure set.