Adenosine thallium-201 tomography in evaluation of graft patency late after coronary artery bypass graft surgery.

OBJECTIVES: We sought to ascertain the utility of adenosine thallium-201 tomography for assessing graft stenoses late after coronary artery bypass graft surgery. BACKGROUND: Although pharmacologic perfusion imaging has been increasingly used in the assessment of patients with coronary artery disease, the value of this stress modality for detecting coronary artery bypass graft stenosis late after surgery is unknown. METHODS: We studied 109 patients who underwent both adenosine thallium-201 tomography and coronary angiography at 6.7 +/- 4.8 (mean +/- SD) years after coronary artery bypass graft surgery. Adenosine thallium-201 tomography was assessed quantitatively by computer-generated polar maps of the myocardial thallium-201 activity. RESULTS: On coronary angiography, significant graft stenoses were present in 68 patients, 65 of whom had a corresponding perfusion defect as shown by thallium-201 tomography (sensitivity 96%). Significant stenoses were present in 107 (37.8%) of 283 grafts. The overall specificity by quantitative tomography was 61%. Seventy percent of the apparently false positive perfusion defects could be explained on the basis of unbypassed native disease or by the presence of fixed defects in patients with previous myocardial infarction. CONCLUSIONS: Thus, results of adenosine thallium-201 tomography are nearly always abnormal in patients with late coronary graft stenosis. Most of the false positive defects appear to be due to either unbypassed native disease or a previous myocardial infarction.

The early morning rise in blood pressure is related mainly to ambulation.

The marked increase in cardiovascular events that occur in the early morning hours could be related to a significant rise in blood pressure at this time but there is uncertainty as to whether this rise in pressure occurs before, at, or after awakening. Automatic blood pressure and pulse measurements were taken twice on 15 normotensive subjects and three times on 11 untreated hypertensive subjects starting before the onset of sleep and at 10 min intervals for 1 h before and 60 to 90 min after awakening. In random order, all subjects either remained supine or immediately arose and ambulated on the first two occasions. The hypertensives had a third study involving ingestion of 10 mg nifedipine after awakening and remaining supine for the next 60 min. The blood pressure and pulse changed little before and after awakening if the subjects remained supine. They rose rapidly and significantly immediately upon arising. The rise in pressure upon arising was blunted by the prior ingestion of nifedipine. The early morning rise in blood pressure and pulse is mainly related to arising from bed. Possible ways to reduce the abrupt rise in blood pressure and the increase in cardiovascular events that occur after arising are suggested.

Alpha-blocker therapy of hypertension. An unfulfilled promise.

For various reasons, the alpha 1-receptor blocker prazosin has been used infrequently as initial therapy for hypertension. The introduction of additional agents of this class with properties different from prazosin provides slower onset of action, which should reduce the degree of first-dose and postural hypotension and a longer duration of action, which allows for once-a-day dosage. A summary of the published data on efficacy, side effects, and special properties of this class of agents indicates that they will probably be used more extensively, particularly because of their ability to improve lipid and glucose-insulin metabolism.

Influence of adjunctive balloon angioplasty on coronary blood flow after rotational atherectomy.

Rotational atherectomy is being performed with increasing frequency in a distinct subset of patients whose lesion characteristics are unfavorable for conventional balloon angioplasty. Although satisfactory luminal enlargement can be accomplished with the use of rotational atherectomy alone in some patients, adjunctive balloon angioplasty is necessary in most patients, to obtain a minimal residual angiographic result. To demonstrate responses associated with rotational atherectomy results, serial coronary blood flow measurements were obtained in a patient undergoing rotational atherectomy for unstable angina. Adjunctive balloon angioplasty resulted in normalization of post-stenotic coronary flow reserve. Recanalization by rotablator alone may not normalize coronary flow despite a satisfactory angiographic result.

Transesophageal echocardiography in critically ill patients: feasibility, safety, and impact on management.

Transesophageal echocardiography (TEE) is being used with increasing frequency in critically ill patients in whom transthoracic echocardiography (TTE) is often unsatisfactory in providing much needed information. We reviewed the indications, feasibility, and clinical impact of TEE in the intensive care setting at our institution. TEE was performed in 77 critically ill patients (age range 19 to 83 years) in whom TTE was inadequate or inconclusive. The general indications for performing a TEE were as follows: Hemodynamic instability (41%), possible endocarditis (34%), possible embolic source (21%), and possible aortic dissection (4%). In the subset of patients with hemodynamic instability, severe native mitral regurgitation was the most common underlying cause (25%), followed by hypovolemia after cardiac surgery (22%). TEE was feasible in all patients, 47% of whom were on mechanical ventilation. Two patients required stabilization before TEE, including a femoral artery-to-vein bypass in a patient with shock from a prosthetic valve obstruction. Complications, none of which proved to be fatal, occurred in two. Echocardiography led to a significant change in patient management in 46 of the 77 patients (60%), of which 48% was due solely to TEE. In these patients (n = 37), the TEE findings led to a change in medical management in 19% and to surgical intervention in 29%. While TTE remains the first line of diagnostic ultrasound and Doppler in critically ill patients, it can be technically difficult or inconclusive. In this setting, TEE provides a safe and powerful diagnostic tool that can help guide patient management.

Determination of angiographic (TIMI grade) blood flow by intracoronary Doppler flow velocity during acute myocardial infarction.

BACKGROUND: This study compared angiographically graded coronary blood flow with intracoronary Doppler flow velocity in patients during percutaneous transluminal coronary angioplasty (PTCA) for acute myocardial infarction. Different TIMI angiographic flow grades (flow grades based on results of the Thrombolysis in Myocardial Infarction trial) have been associated with different clinical results after reperfusion for acute myocardial infarction. However, intracoronary blood flow velocity has not been compared with the angiographic method of determining flow grade in patients. METHODS AND RESULTS: Coronary flow velocity (measured by use of a Doppler guidewire) during primary or rescue PTCA in 41 acute myocardial infarction patients was compared with TIMI grade and cineframes-to-opacification count. Before PTCA, 34 patients had TIMI grade 0 or 1, 5 had TIMI grade 2, and 2 had TIMI grade 3 flow in the infarct artery. Flow velocity was similar among patients with TIMI grades 0, 1, or 2 but was lower than in those with TIMI grade 3 flow (9.4 +/- 5.4 versus 16.0 +/- 5.4 cm/s for TIMI grades < or = 2 versus TIMI grade 3, respectively; P < .05). After PTCA, 1 patient had TIMI grade 1, 5 had TIMI 2, and 35 had TIMI 3 flow. Poststenotic flow velocity increased from 6.6 +/- 6.1 to 20.0 +/- 11.1 cm/s (P < .01). TIMI grade 3 flow increased to 21.8 +/- 10.9 cm/s (P < .05 versus before PTCA). Although post-PTCA flow velocity correlated with angiographic cineframes-to-opacification count (r = .45; P < .02) for TIMI grade 3, there was a large overlap with TIMI grades < or = 2 that had low flow velocity (< 20 cm/s). Nine of 11 clinical events (unstable angina and coronary artery bypass graft surgery) occurred in patients with low coronary flow velocity. CONCLUSIONS: Determination of flow velocity after reperfusion may enhance patient characterization and provide the physiological rationale for clinical variations after reperfusion therapy.

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.