Quantification of lumen stenoses with known dimensions by conventional angiography and computed tomography: implications of using conventional angiography as gold standard.

BACKGROUND: Quantitative coronary angiography (QCA) has inherent limitations for displaying complex vascular anatomy, yet it remains the gold standard for stenosis quantification. OBJECTIVE: To investigate the accuracy of stenosis assessment by multi-detector computed tomography (MDCT) and QCA compared to known dimensions. METHODS: Nineteen acrylic coronary vessel phantoms with precisely drilled stenoses of mild (25%), moderate (50%) and severe (75%) grade were studied with 64-slice MDCT and digital flat panel angiography. Fifty-seven stenoses of circular and non-circular shape were imaged with simulated cardiac motion (60 bpm). Image acquisition was optimised for both imaging modalities, and stenoses were quantified by blinded expert readers using electronic callipers (for MDCT) or lumen contour detection software (for QCA). RESULTS: Average difference between true and measured per cent diameter stenosis for QCA was similar compared to MDCT: 7 (+/-6)% vs 7 (+/-5)% (p=0.78). While QCA performed better than MDCT in stenoses with circular lumen (mean error 4 (+/-3)% vs 7 (+/-6)%, p<0.01), MDCT was superior to QCA for evaluating stenoses with non-circular geometry (mean error 10 (+/-7)% vs 7 (+/-5)%, p<0.05). In such lesions, QCA underestimated the true diameter stenosis by >20% in 9 of 27 (33%) vs 1 of 29 (3%) in lumen with circular geometry. CONCLUSIONS: QCA often underestimates diameter stenoses in lumen with non-circular geometry. Compared to QCA, MDCT yields mildly greater measurement errors in perfectly circular lumen but performs better in non-circular lesions. These findings have implications for using QCA as the gold standard for stenosis quantification by MDCT.

Assessment of coronary arterial restenosis with phase-contrast magnetic resonance imaging measurements of coronary flow reserve.

BACKGROUND: After successful percutaneous coronary arterial revascularization, 25% to 60% of subjects have restenosis, a recurrent coronary arterial narrowing at the site of the intervention. At present, restenosis is usually detected invasively with contrast coronary angiography. This study was performed to determine if phase-contrast MRI (PC-MRI) could be used to detect restenosis noninvasively in patients with recurrent chest pain after percutaneous revascularization. METHODS AND RESULTS: Seventeen patients (15 men, 2 women, age 36 to 77 years) with recurrent chest pain >3 months after successful percutaneous intervention underwent PC-MRI measurements of coronary artery flow reserve followed by assessments of stenosis severity with computer-assisted quantitative coronary angiography. The intervention was performed in the left anterior descending coronary artery in 15 patients, one of its diagonal branches in 2 patients, and the right coronary artery in 1 patient. A PC-MRI coronary flow reserve value /=70% and >/=50%, respectively. CONCLUSIONS: Assessments of coronary flow reserve with PC-MRI can be used to identify flow-limiting stenoses (luminal diameter narrowings >70%) in patients with recurrent chest pain in the months after a successful percutaneous intervention.

Rotational atherectomy.

Rotational atherectomy is used most often to treat stenoses that are calcified, located at an arterial ostium or at the site of a bifurcation, or resulting from in-stent restenosis. The atherectomy device debulks soft and calcified plaque while minimizing injury to adjacent normal arterial segments. In a randomized comparison with excimer laser and balloon angioplasty, rotational atherectomy achieved a statistically higher procedural success rate without an increased incidence of major complications. Patients with lesions that were more complex derived the greatest benefit from rotational atherectomy. To date, rotational atherectomy usually is performed in conjunction with a) the intracoronary infusion of a "cocktail" containing verapamil, heparin, and nitroglycerin; b) the intravenous infusion of a glycoprotein IIb/IIIa receptor antagonist, such as abciximab; c) a stepped burr approach, leading to a burr:artery ratio of 0.8; d) burr rotations <30 seconds in duration; e) avoidance of burr deceleration; and f) low-pressure balloon angioplasty. Under these circumstances, it has a procedural success rate of 98% and a major complication rate of <2%.

Percutaneous mitral balloon valvuloplasty.

Almost all mitral stenosis (MS) is rheumatic in etiology. The patient with MS who is symptomatic despite medical therapy should undergo percutaneous mitral balloon valvuloplasty or mitral valvular surgery (commissurotomy or replacement). The choice of procedure is determined by patient preference and the echocardiographic morphologic features of the valvular and subvalvular apparati. With balloon valvuloplasty, the rate of success is > 90%. At institutions where operators are experienced with balloon valvuloplasty and open surgical commissurotomy, their acute and long-term results are comparable. Balloon valvuloplasty occasionally is associated with complications, including death in 0 to 1%, moderate or severe valvular regurgitation in 3 to 5%, and systemic embolization in 1 to 3%.

Late revascularization reduces mortality in survivors of myocardial infarction.

In survivors of acute myocardial infarction, the restoration of antegrade flow in the infarct-related coronary artery may improve prognosis by a mechanism that is independent of its influence on left ventricular systolic performance. Furthermore, survival may be improved even when antegrade flow is restored days or even weeks after the acute event. In several retrospective studies of survivors of infarction, we and others have shown a) that long-term survival is substantially better in those with-as opposed to those without-antegrade flow in the infarct-related coronary artery, and b) that the mechanical restoration of flow in an occluded infarct-related artery (accomplished with balloon angioplasty or bypass grafting) markedly improves long-term survival. The late restoration of antegrade flow in the infarct-related artery appears to render the so-called border zone of infarction less electrically unstable, thereby reducing the likelihood of ventricular tachyarrhythmias and sudden death.

Thrombolysis versus primary percutaneous transluminal coronary angioplasty for acute myocardial infarction.

For the patient with acute myocardial infarction (MI), both primary percutaneous transluminal coronary angioplasty (PTCA) and intravenous thrombolytic therapy are effective in restoring antegrade coronary blood flow, improving left ventricular systolic function, and reducing mortality. Primary PTCA is effective when performed quickly by experienced operators. It is the preferred therapy in the patient a) with a contraindication to thrombolytic therapy, b) aged 70 years or older, and c) in whom thrombolytic therapy is likely to be ineffective (ie, the patient with cardiogenic shock). Thrombolytic therapy is widely available and can be given quickly and easily. As a result, it remains the treatment of choice for most patients with acute MI. The goal of therapy for the patient with acute MI is the rapid and sustained restoration of coronary blood flow. For the individual patient, the better therapy-primary PTCA or thrombolytic therapy-is the one that can be given more safely and expeditiously.

Aggressive versus conservative therapy in unstable angina.

In patients with unstable angina, non-Q-wave, and Q-wave myocardial infarction, atherosclerotic plaque rupture leads to a variable amount of platelet adhesion and aggregation, vasoconstriction, and partially or totally occlusive thrombus formation. This article focuses on the role of aggressive (routine angiography and revascularization) versus conservative (maximal medical therapy, with catheterization and revascularization reserved for those with spontaneous or provable ischemia) management of the patient with unstable angina.

Visualization and functional assessment of proximal and middle left anterior descending coronary stenoses in humans with magnetic resonance imaging.

BACKGROUND: Coronary artery bypass grafting improves survival in patients with >70% luminal diameter narrowing of the 3 major epicardial coronary arteries, particularly if there is involvement of the proximal portion of the left anterior descending (LAD) coronary artery. Measurement of coronary flow reserve can be used to identify functionally important luminal narrowing of the LAD artery. Although magnetic resonance imaging (MRI) has been used to visualize coronary arteries and to measure flow reserve noninvasively, the utility of MRI for detecting significant LAD stenoses is unknown. METHODS AND RESULTS: Thirty subjects (23 men, 7 women, age 36 to 77 years) underwent MRI visualization of the left main and LAD coronary arteries as well as measurement of flow in the proximal, middle, or distal LAD both at rest and after intravenous adenosine (140 microgram/kg per minute). Immediately thereafter, contrast coronary angiography and when feasible, intracoronary Doppler assessments of coronary flow reserve, were performed. There was a statistically significant correlation between MRI assessments of coronary flow reserve and (a) assessments of coronary arterial stenosis severity by quantitative coronary angiography and (b) invasive measurements of coronary flow reserve (P<0.0001 for both). In comparison to computer-assisted quantitative coronary angiography, the sensitivity and specificity of MRI for identifying a stenosis >70% in the distal left main or proximal/middle LAD arteries was 100% and 83%, respectively. CONCLUSIONS: Noninvasive MRI measures of coronary flow reserve correlated well with similar measures obtained with the use of intracoronary Doppler flow wires and predicted significant coronary stenoses (>70%) with a high degree of sensitivity and specificity. MRI-based measurement of coronary flow reserve may prove useful for identification of patients likely to obtain a survival benefit from coronary artery bypass grafting.

Predictive value of prominent right atrial V waves in assessing the presence and severity of tricuspid regurgitation.

Neither "prominent" right atrial V waves nor an elevated mean right atrial pressure reliably predicts the presence of moderate or severe tricuspid regurgitation. On the other hand, the absence of prominent right atrial V waves and an elevated mean right atrial pressure are relatively specific for the absence of moderate or severe tricuspid regurgitation.

Platelet glycoprotein IIb/IIIa receptor blockade: lessening the risk of coronary interventions.

For the patient undergoing percutaneous coronary intervention, the administration of a platelet glycoprotein IIb/IIIa receptor blocker reduces the incidence of a periprocedural nonfatal myocardial infarction and the need for unplanned emergency stenting. In the diabetic patient undergoing intracoronary stenting, the use of a platelet glycoprotein IIb/IIIa receptor blocker appears to decrease the need for subsequent target vessel revascularization. There is considerable evidence in support of the use of glycoprotein IIb/IIIa receptor inhibitors in all categories of patients--"high-risk" patients, "low-risk" patients, and those undergoing primary angioplasty for acute myocardial infarction--and for the full armamentarium of percutaneous procedures (angioplasty, directional atherectomy, rotational atherectomy, and intracoronary stenting).

The Eisenmenger syndrome in adults.

For this article, the literature on the pathophysiology, clinical features, natural history, prognosis, and management of the Eisenmenger syndrome in adults was reviewed. English-language articles from 1966 to the present were identified through a search of the MEDLINE database by using the terms Eisenmenger, congenital heart disease, and pulmonary hypertension. Selected cross-referenced articles were also included. Articles on the pathophysiology, clinical presentation, evaluation, natural history, complications, and treatment of the Eisenmenger syndrome in adults were selected, and descriptive and analytical data relevant to the practicing physician were manually extracted. The Eisenmenger syndrome is characterized by elevated pulmonary vascular resistance and right-to-left shunting of blood through a systemic-to-pulmonary circulation connection. Most patients with the syndrome survive for 20 to 30 years. The hemostatic changes associated with the syndrome may lead to thromboembolic events, cerebrovascular complications, or the hyperviscosity syndrome. Erythrocytosis is present in most patients, but excessive phlebotomy may cause microcytosis and exacerbate the symptoms of hyperviscosity. Other complications associated with the Eisenmenger syndrome include hemoptysis, gout, cholelithiasis, hypertrophic osteoarthropathy, and decreased renal function. Pregnancy or noncardiac surgery is associated with a high mortality rate in patients with the Eisenmenger syndrome. Because most pediatric patients with the Eisenmenger syndrome survive to adulthood, primary care physicians should have a thorough understanding of the syndrome; its associated complications; and medical and surgical management, especially with regard to the appropriate timing of phlebotomy and lung or heart-lung transplantation. In addition, patients with the syndrome should undergo routine follow-up at a tertiary care center that has physicians and nurses with special expertise in congenital heart disease. In patients with the Eisenmenger syndrome who are pregnant or require noncardiac surgery, a multidisciplinary approach should be used to reduce the excessive mortality associated with these conditions.

Intracardiac shunts resulting from transseptal catheterization for ablation of accessory pathways in otherwise normal hearts.

In a series of 14 patients undergoing transseptal catheterization for ablation of left-sided accessory pathways, hydrogen appearance time was used to detect left-to-right shunting after removal of the catheter. Six of the 12 patients who had no evidence of shunt before catheterization had evidence of shunting after the procedure.