Spontaneous coronary artery dissection in a pregnant woman.

BACKGROUND: Spontaneous coronary dissection is a rare condition occurring more often in women, with a higher frequency during the peripartum period. No specific etiology has been defined to describe this uncommon, yet often fatal phenomenon. CASE: A young woman presented at 36 weeks of a noncomplicated pregnancy with recent onset of diaphoresis, dyspnea, and tingling substernal chest discomfort. Upon evaluation, she developed cardiovascular collapse and ventricular fibrillation requiring aggressive resuscitative measures, eventually leading to extracorporeal membrane oxygenation. Right coronary artery dissection was ultimately diagnosed and treated with intracoronary angioplasty and stent placement. CONCLUSION: Spontaneous coronary dissection must be considered when evaluating a patient with a similar clinical presentation, given its overall mortality of more than 50% at presentation, particularly in the peripartum period.

Ultraharmonic myocardial contrast imaging: in vivo experimental and clinical data from a novel technique.

Myocardial contrast echocardiography (MCE) with high-mechanical-index (MI), triggered harmonic imaging is the best-established technique to date for the assessment of myocardial perfusion. A high signal-to-noise ratio, which is significantly influenced by precontrast tissue signals, is an important prerequisite. Our goal was to evaluate the efficacy of ultraharmonic MCE, a technique that rejects tissue signals by receiving signals beyond the second but below the third harmonic. Imaging was performed in 6 closed-chest dogs and in 15 healthy volunteers (11 of whom also had dipyridamole stress). Analyses of videointensity (VI) confirmed uniformly low precontrast tissue VI, a significant increase of postcontrast VI (before and after dipyridamole), and a significant decrease in VI after microbubble destruction. We conclude that ultraharmonic MCE produces low precontrast tissue signals, thus optimizing postcontrast myocardial opacification, and exhibits efficient microbubble destruction with use of multiple-frame triggering. Thus this new technique opens up a new possibility of further optimizing coronary microcirculation imaging with microbubbles.

Real-time myocardial blood flow imaging in normal human beings with the use of myocardial contrast echocardiography.

Triggered myocardial contrast echocardiography (MCE) has been used successfully to quantify myocardial blood flow and assess coronary stenosis in animal models, but practical considerations have limited its broad clinical use. Real-time MCE may have practical advantages to assess perfusion and real time myocardial blood flow in human beings. We compared real-time MCE with triggered imaging in 23 normal human volunteers by using an investigational ultrasound contrast agent (DMP-115) and a commercially available ultrasound platform (Acuson Sequoia). Peak myocardial opacification (reflecting myocardial blood volume) after contrast infusion was quantified digitally in gray scale units (GU). In 13 subjects, myocardial blood flow reserve was assessed during dipyridamole infusion with the use of intermittent destruction-replenishment techniques. Real-time MCE resulted in a 30- to 45-GU increase from baseline compared with a 20- to 70-GU increase with triggered imaging. Real-time MCE showed no statistical difference in opacification (P = .131 by analysis of variance) among any of the myocardial regions of interest. Triggered imaging resulted in heterogeneous opacification among the regions of interest (P < .05 by analysis of variance). Dipyridamole did not significantly change peak myocardial opacification (myocardial blood volume) for either technique. Quantification of flow reserve revealed that myocardial blood flow reserve for the dipyridamole group was 3.6 +/- 0.4 (mean +/- 1 standard error of the mean). Real-time MCE is feasible in normal human volunteers and provides homogenous opacification of the myocardium. Furthermore, quantification of myocardial blood flow with real-time MCE in normal human beings produces results that are consistent with the known physiology of the coronary microcirculation.

Power Doppler myocardial contrast echocardiography using an improved multiple frame triggered Harmonic Angio technique.

Although B-mode harmonic, intermittent-triggered myocardial contrast echocardiography (MCE) is a well-established technique, a variety of MCE techniques have been introduced recently to improve myocardial opacification. One such technique uses a power Doppler method in conjunction with multiple frame triggering (MFT), but has been limited by nonuniform microbubble destruction and blooming as well as motion artifacts. Utilizing two different contrast agents, Definity and Optison, we tested the feasibility of an improved version of Harmonic Angio MFT that utilizes a lower transmit frequency, reduced packet size, and more stringent wall filter in normal volunteers and in patients with known perfusion defects. The results showed that Harmonic Angio MFT produced fill frames with readily visible opacification and destruction frames with little visible opacification. The patterns of opacification also correlated with the expected perfusion patterns in both groups of subjects. Thus, Harmonic Angio MFT appears to be a promising new MCE technique.