Steven C. Herrmann

Coronary Hyperemic Dose Responses of Intracoronary Sodium Nitroprusside

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-&mgr;g boluses), and after 3 serial doses (0.3-, 0.6-, and 0.9-&mgr;g/kg boluses) of intracoronary nitroprusside. Coronary reserve was calculated as hyperemia/basal coronary flow velocity. In an additional 9 patients with intermediate stenoses (53±7%), 14 fractional flow reserve (FFR) measurements (using 0.014-inch pressure wire) were performed with both intracoronary adenosine and nitroprusside (0.6 &mgr;g/kg). Intracoronary nitroprusside produced equivalent coronary hyperemia with a longer duration (≈25%) compared with intracoronary adenosine. Intracoronary nitroprusside (0.9 &mgr;g/kg) decreased systolic blood pressure by <20%, 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 (r =0.97). 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.

Comparison of myocardial contrast echocardiography derived myocardial perfusion reserve with invasive determination of coronary flow reserve

AIMS Invasive measurements of coronary flow reserve (CFR) by Doppler flow wire are an established method for determining coronary blood flow physiology. Myocardial contrast echocardiography (MCE) is a potential non-invasive method for quantifying myocardial blood flow (MBF). However, few studies have compared MCE-derived myocardial perfusion reserve (MPR) with Doppler flow wire-derived CFR, measured simultaneously in human subjects. This study aimed to correlate MCE-derived MPR with Doppler flow wire-derived CFR. METHODS AND RESULTS Ten patients with at least two angiographically normal coronary arteries underwent simultaneous invasive Doppler flow wire measurements and MCE imaging at rest and at peak hyperaemia. Hyperaemia was induced by intravenous adenosine infusion. Doppler-derived CFR was calculated as the ratio of hyperaemic to baseline average peak red blood cell velocity. MPR was calculated as the hyperaemic to baseline ratio of the following parameters: myocardial blood volume (MBV), myocardial microbubble velocity (MMV), and MBF. MCE was performed using real-time and triggered imaging with contrast infused intravenously by bolus and continuous methods. Regardless of whether the contrast was infused by bolus or continuous methods, Doppler flow wire-derived CFR had a stronger correlation with MPR derived by MBV (r=0.8, P=0.05) than with MPR derived by microbubble velocity (r=0.3, P>0.05) or MBF (r=0.4, P>0.05). Real-time imaging with continuous infusion provided better correlation with CFR than triggered imaging methods or bolus administration. CONCLUSION Myocardial perfusion reserve derived by real-time infusion MBV measurements correlates with Doppler flow wire-derived CFR. Therefore, MPR may be a potential surrogate for Doppler flow wire-derived CFR in patients with angiographically normal coronary arteries.

Efficacy of Atropine as a Chronotropic Agent in Heart Transplant Patients Undergoing Dobutamine Stress Echocardiography

Background: After heart transplant (HTX), the heart is completely denervated. While sympathetic reinnervation is likely to occur, there is conflicting evidence regarding parasympathetic reinnervation. Accordingly, it is unclear if atropine is efficacious as a chronotropic agent in HTX patients undergoing dobutamine stress echocardiography (DSE), since cholinergic cardiac stimulation is required for atropine to exert its effect. The purpose of this study was to demonstrate that atropine can sufficiently increase the heart rate (HR) in HTX patients undergoing DSE. Methods: A retrospective review was performed on 68 HTX patients who underwent DSE as part of their routine annual HTX follow‐ups. Dobutamine was administered in the standard fashion of 10, 20, 30, 40, 50 mcg/kg per minute with blood pressure and electrocardiographic monitoring. If target HR was not attained, atropine was administered to aid in achieving 85% of maximum age‐predicted HR. Results: Mean patient age was 58 ± 10 years. Mean period since transplant was 9 ± 4 years. Forty‐seven (69%) patients received dobutamine only, and 21 (31%) required additional atropine to reach target HR. Of the 21 patients who received atropine, 10 (48%) reached target HR. Neither time from transplant, age, gender, resting HR, medications, nor atherosclerotic risk factors predicted responsiveness to atropine. Those responding to dobutamine had a significantly greater resting HR than those receiving additional atropine. Conclusions: The adjunctive use of atropine in HTX patients during DSE aids in reaching 85% of maximum predicted HR in some patients. Furthermore, resting HR may predict the additional need of atropine during DSE.

Influence of percutaneous transluminal coronary rotational atherectomy with adjunctive percutaneous transluminal coronary angioplasty on coronary blood flow

The purpose of this study was to examine the influence of sequential percutaneous transluminal coronary rotational atherectomy (PTCRA) and coronary angioplasty on coronary blood flow reserve in patients. Rotational coronary atherectomy restores lumen patency by partially ablating fibrocalcific plaque, releasing microparticulate debris into the distal coronary circulation. Adjunctive balloon angioplasty is usually performed to optimize the angiographic luminal dimensions. Serial alterations in coronary physiology have not been reported. Fourteen lesions in 13 patients were treated by sequential rotational atherectomy followed by adjunctive balloon angioplasty. Poststenotic baseline coronary blood flow velocity was measured by using a Doppler flow wire (FloWire, Cardiometrics, Inc., Mountain View, Calif.), and coronary blood flow was calculated by using the distal vessel cross-sectional area obtained by quantitative coronary angiography. Data were acquired at baseline and during hyperemia (12 to 18 microg of intracoronary adenosine), before and after PTCRA, and again after balloon angioplasty. The mean stenosis decreased from 76 percent +/- 12 percent at baseline to 21 percent +/- 11 percent at the completion of the procedure (p<0.01). The minimal luminal diameter (by quantitative coronary angiography) was 0.7 +/- 0.4 mm at baseline, increased to 1.9 +/- 0.4 mm after rotational atherectomy (p<0.01), and increased to 2.4 +/- 0.5 mm after balloon angioplasty (p<0.01 versus baseline and PTCRA). Distal (poststenotic) coronary blood flow at baseline was 47 +/- 23 ml/min and 57 +/- 38 ml/min during hyperemia. After PTCRA, coronary blood flow increased to 104 +/- 59 ml/min and to 132 +/- 73 ml/min with hyperemia. After adjunctive angioplasty, coronary blood flow was 84 +/- 40 ml/min (p=not significant [NS] vs PTCRA) and increased to 143 +/- 81 ml/min with hyperemia (p=NS vs PTCRA). The poststenotic coronary flow reserve increased from an initial value of 1.1 +/- 0.2 ml/min to 1.3 +/- 0.3 ml/min after PTCRA (p=NS vs baseline) and to 1.6 +/- 0.3 ml/min after adjunctive balloon angioplasty (p<0.01 vs p=NS vs PTCRA). PTCRA significantly increased resting coronary blood flow. Adjunctive balloon angioplasty did not significantly augment resting or hyperemic coronary blood flow more than that achieved by rotational atherectomy alone. These data demonstrate that PTCRA alone improves baseline coronary blood flow with minimal additional physiologic change after adjunctive balloon angioplasty.

Intravascular ultrasound and fractional flow reserve of equivocal left main stenosis in patients with Takayasu's arteritis: impact on surgical decision-making.

A 40-year-old white woman was transferred from an outside hospital to our facility. Six months prior to admission, the patient experienced transient right visual loss for 2 days associated with sharp neck pain. A temporal artery biopsy at that time was negative for temporal arteritis. Over the ensuing several months, the patient had increasing episodes of intermittent vision loss in the right eye associated with right-sided neck pain. Two weeks prior to admission, the patient experienced right facial numbness and slurred speech lasting several hours. She was seen in the emergency room and sent home after a head CT was unrevealing. Several days later, the patient had a syncopal episode. She was diagnosed with panic attacks and again sent home. One week later, the patient was admitted to an outside hospital with right facial numbness and weakness, right facial droop, right upper and lower extremity weakness, and headaches. A magnetic resonance angiogram (MRA) of the aortic arch and branch vessels revealed total occlusion of the right brachiocephalic trunk at its origin. She was then transferred to our facility for further evaluation and treatment. Her past medical history was significant for bipolar disorder, hysterectomy secondary to cervical cancer, and hypercholesterolemia. Her home medications were Ativan, Zoloft, Zyprexa, and Premarin. She was allergic to codeine, Ceclor, sulfa, and iodine. Her father had three strokes by the age of 63. Hypertension was noted in several family members. The patient smokes one pack a day for the past 20 years. Review of systems included intermittent substernal pressure-like chest pain that radiates to the left shoulder. The patient was admitted to the neurology service at St. Louis University Hospital. Further questioning revealed a 6-month history of exertional chest pressure with associated dyspnea on exertion with a 1-week history of chest pressure occurring at rest with increasing frequency. There was also a history of presyncope and syncopal episodes with movement of the right upper extremity and right upper extremity claudication. On physical examination, her blood pressure was 90/60 in the right arm and 120/70 in the left arm. Skin, head, eye, ear, and throat examination revealed decreased visual acuity in the right eye. There was no jugular venous distention. There was a left carotid and left supraclavicular bruit. Cardiac examination revealed a normal first and second heart sound, with a regular rate rhythm and rhythm and no murmurs, rubs, or

Feasibility of Performing Real-Time Myocardial Contrast Echocardiography During Clinical Dobutamine Stress Echocardiography in Technically Difficult Patients:

Myocardial contrast echocardiography (MCE) has emerged as an alternative to nuclear medicine perfusion imaging. The aim of this study was to evaluate the feasibility of performing and the interpretation of MCE for perfusion imaging in a clinical laboratory. The study population consisted of 150 consecutive patients referred for dobutamine stress echocardiography (DSE) to determine the presence of myocardial ischemia. Echocardiographic perfusion images were digitized at rest and at peak dobutamine infusion for later review. A total of 12 myocardial segments in the apical four and two chamber views were graded as no perfusion, minimal perfusion, definite perfusion, or not able to evaluate. Of 3600 possible segments, a total of 2926 (81%) were able to be graded at either rest or peak dobutamine. At rest, 79% of segments were graded for perfusion (1419 of 1800 segments). At peak dobutamine infusion, 84% of segments were graded for perfusion (1507 of 1800 segments). The results demonstrate that MCE is clinically feasible to perform and interpret during DSE on a routine daily basis.