Myocardial edema imaging in acute coronary syndromes.

Acute coronary syndromes (ACS) continue to be the most common morbid condition of industrialized nations. The advent of and technical improvements in revascularization and medical therapy have led to a steady decline in mortality rates. However, many patients who suffer unstable angina or myocardial infarction require further testing and risk stratification to guide therapeutic selection and prognosis assignment. Myocardial edema imaging with cardiac magnetic resonance (CMR) affords the ability to define the amount of myocardium at risk, refine estimates of prognosis and provide guidance for therapies with excellent sensitivity compared with standard clinical markers. This review will discuss the rationale for edema imaging, how it is performed using CMR, and potential clinical applications.

Persistent pulmonary hypertension after mitral valve surgery: does surgical procedure affect outcome?

BACKGROUND AND AIM OF THE STUDY: Recently published data suggest that prosthesis-patient mismatch is common after mitral valve replacement (MVR), and manifests as persistent pulmonary hypertension. The study aim was to determine the prevalence and severity of pulmonary hypertension after mitral valve surgery, including mitral valve repair, and to determine whether surgery type affects the prevalence of post-operative pulmonary hypertension. METHODS: Matched preoperative and > or =1 year postoperative Doppler estimates of right ventricular systolic pressure (RVSP) were evaluated in a cohort of 179 patients who underwent MVR or repair (33 after bioprosthetic valve replacement, 20 after mechanical valve replacement, 43 after physiological valve repair (predominantly for myxomatous disease), 78 after undersized annuloplasty for functional regurgitation, and five after repair of rheumatic stenosis). RESULTS: Patients undergoing repair of function mitral regurgitation had a lower left ventricular ejection fraction. The postoperative mean transmitral gradient was slightly higher for patients after bioprosthetic valve replacement (6.9 +/- 2.6 mmHg) compared to mechanical valve replacement (5.2 +/- 2.8 mmHg; p = 0.03), physiological repair (5.2 +/- 2.8 mmHg; p = 0.05), or repair of functional regurgitation (5.5 +/- 2.8 mmHg; p = 0.02). Pulmonary hypertension was common (present in 78% of patients before and 64% after surgery), and there were no significant differences between groups in the prevalence of postoperative pulmonary hypertension. The RVSP tended to decrease in all groups, but reached statistical significance only for patients undergoing bioprosthetic replacement (-9 +/- 24 mmHg; p = 0.04), mechanical replacement (-10 +/- 14 mmHg; p = 0.003) or physiological repair (-6 +/- 16 mmHg; p = 0.01). CONCLUSION: Pulmonary hypertension is common before and after mitral valve surgery. Although there were at least trends toward lower pulmonary artery pressures regardless of surgery type, significant decreases were noted only after MVR and physiological repair. A slightly higher postoperative mean transmitral gradient after bioprosthetic valve replacement may have contributed to postoperative pulmonary hypertension. The physiological repair of organic, non-rheumatic mitral regurgitation appears to offer favorable hemodynamics and a relatively low rate of postoperative pulmonary hypertension.

Simultaneous right and left heart real-time, free-breathing CMR flow quantification identifies constrictive physiology.

OBJECTIVES: The purpose of this study was to evaluate the ability of a novel cardiac magnetic resonance (CMR) real-time phase contrast (RT-PC) flow measurement technique to reveal the discordant respirophasic changes in mitral and tricuspid valve in flow indicative of the abnormal hemodynamics seen in constrictive pericarditis (CP). BACKGROUND: Definitive diagnosis of CP requires identification of constrictive hemodynamics with or without pericardial thickening. CMR to date has primarily provided morphological assessment of the pericardium. METHODS: Sixteen patients (age 57 ± 13 years) undergoing CMR to assess known or suspected CP and 10 controls underwent RT-PC that acquired simultaneous mitral valve and tricuspid valve inflow velocities over 10 s of unrestricted breathing. The diagnosis of CP was confirmed via clinical history, diagnostic imaging, cardiac catheterization, intraoperative findings, and histopathology. RESULTS: Ten patients had CP, all with increased pericardial thickness (6.2 ± 1.0 mm). RT-PC imaging demonstrated discordant respirophasic changes in atrioventricular valve inflow velocities in all CP patients, with mean ± SD mitral valve and tricuspid valve inflow velocity variation of 46 ± 20% and 60 ± 15%, respectively, compared with 16 ± 8% and 24 ± 11% in patients without CP (p < 0.004 vs. patients with CP for both) and 17 ± 5% and 31 ± 13% in controls (p < 0.001 vs. patients with CP for both). There was no difference in atrioventricular valve inflow velocity variation between patients without CP compared with controls (p > 0.3 for both). Respiratory variation exceeding 25% across the mitral valve yielded a sensitivity of 100%, a specificity of 100%, and an area under the receiver-operating characteristic curve of 1.0 to detect CP physiology. Using a cutoff of 45%, variation of transtricuspid valve velocity had a sensitivity of 90%, a specificity of 88%, and an area under the receiver-operating characteristic curve of 0.98. CONCLUSIONS: Accentuated and discordant respirophasic changes in mitral valve and tricuspid valve inflow velocities characteristic of CP can be identified noninvasively with RT-PC CMR. When incorporated into existing CMR protocols for imaging pericardial morphology, RT-PC CMR provides important hemodynamic evidence with which to make a definite diagnosis of CP.

Advances in CT angiography for peripheral arterial disease.

Multidetector CT scan (MDCT) has revolutionized the diagnosis of peripheral arterial disease. The most recent generation of CT scan systems increases the number of detector arrays, which allows further increases in volume coverage and acquisition of large volumes rapidly. These have provided advantages in vascular imaging. The introduction of dual-source scanners has allowed the possibility of tissue characterization in CT scans. This article briefly discusses the basic principles of MDCT and provides an overview of its application in vascular diseases.