Outcome of patients with hypertrophic obstructive cardiomyopathy after percutaneous transluminal septal myocardial ablation and septal myectomy surgery.

OBJECTIVES: This study was conducted to evaluate follow-up results in patients with hypertrophic obstructive cardiomyopathy (HOCM) who underwent either percutaneous transluminal septal myocardial ablation (PTSMA) or septal myectomy. BACKGROUND: Controversy exists with regard to these two forms of treatment for patients with HOCM. METHODS: Of 51 patients with HOCM treated, 25 were treated by PTSMA and 26 patients via myectomy. Two-dimensional echocardiograms were performed before both procedures, immediately afterwards and at a three-month follow-up. The New York Heart Association (NYHA) functional class was obtained before the procedures and at follow-up. RESULTS: Interventricular septal thickness was significantly reduced at follow-up in both groups (2.3 +/- 0.4 cm vs. 1.9 +/- 0.4 cm for septal ablation and 2.4 +/- 0.6 cm vs. 1.7 +/- 0.2 cm for myectomy, both p < 0.001). Estimated by continuous-wave Doppler, the resting pressure gradient (PG) across the left ventricular outflow tract (LVOT) significantly decreased immediately after the procedures in both groups (64 +/- 39 mm Hg vs. 28 +/- 29 mm Hg for PTSMA, 62 +/- 43 mm Hg vs. 7 +/- 7 mm Hg for myectomy, both p < 0.0001). At three-month follow-up, the resting PG remained lower in the PTSMA and myectomy groups (24 +/- 19 mm Hg and 11 +/- 6 mm Hg, respectively, vs. those before procedures, both p < 0.0001). The NYHA functional class was also significantly improved in both groups (3.5 +/- 0.5 vs. 1.9 +/- 0.7 for PTSMA, 3.3 +/- 0.5 vs. 1.5 +/- 0.7 for myectomy, both p < 0.0001). CONCLUSIONS: Both myectomy and PTSMA reduce LVOT obstruction and significantly improve NYHA functional class in patients with HOCM. However, there are benefits and drawbacks for each therapeutic method that must be counterbalanced when deciding on treatment for LVOT obstruction.

Percutaneous transluminal alcohol septal myocardial ablation after aortic valve replacement.

When left ventricular outflow tract obstruction develops after aortic valve replacement, few treatment choices have been available until now. We present a patient with prior aortic valve replacement who developed left ventricle outflow tract obstruction that was successfully treated with a percutaneous transcoronary myocardial septal alcohol ablation. This technique is a useful tool for the treatment of obstructive hypertrophic cardiomyopathy, especially in those patients with prior heart surgery.

Qualitative and quantitative effects of harmonic echocardiographic imaging on endocardial edge definition and side-lobe artifacts.

Harmonic imaging is a new ultrasonographic technique that is designed to improve image quality by exploiting the spontaneous generation of higher frequencies as ultrasound propagates through tissue. We studied 51 difficult-to-image patients with blinded side-by-side cineloop evaluation of endocardial border definition by harmonic versus fundamental imaging. In addition, quantitative intensities from cavity versus wall were compared for harmonic versus fundamental imaging. Harmonic imaging improved left ventricular endocardial border delineation over fundamental imaging (superior: harmonic = 71.1%, fundamental = 18.7%; similar: 10.2%; P <.001). Quantitative analysis of 100 wall/cavity combinations demonstrated brighter wall segments and more strikingly darker cavities during harmonic imaging (cavity intensity on a 0 to 255 scale: fundamental = 15.6 +/- 8.6; harmonic = 6.0 +/- 5.3; P <.0001), which led to enhanced contrast between the wall and cavity (1.89 versus 1.19, P <.0001). Harmonic imaging reduces side-lobe artifacts, resulting in a darker cavity and brighter walls, thereby improving image contrast and endocardial delineation.

Percutaneous transluminal septal myocardial ablation.

Percutaneous transluminal septal myocardial ablation (PTSMA) is a new, investigational, catheter-based treatment for severely symptomatic, medically refractory hypertrophic obstructive cardiomyopathy. A balloon catheter is used to cannulate and isolate the first or second septal perforator coronary artery. Following balloon inflation and intracoronary myocardial contrast echocardiography, ethyl alcohol is injected through the catheter lumen to cause proximal interventricular septum infarction and relief of outflow tract obstruction with improved patient symptoms. Septal scarring and thinning with reductions in the outflow tract gradients ensues over the following 6 to 12 weeks. Most patients have symptomatic improvement, at least moderate reductions in outflow tract gradients, and possibly improvement in exercise capacity. The most common procedural complication is the development of high-grade atrioventricular block necessitating implantation of a permanent pacemaker in 25% of patients. Compared with surgical myectomy, PTSMA has the advantage of being minimally invasive, easily repeated, and with relatively low major morbidity/mortality risk for patients with comorbid conditions. The findings from recently initiated international registries will be helpful in assessing the overall success and complication rates with PTSMA.

New imaging technology: measurement of myocardial perfusion by contrast echocardiography.

Myocardial perfusion imaging has long been a goal for the non-invasive echocardiographic assessment of the heart. However, many factors at play in perfusion imaging have made this goal elusive. Harmonic imaging and triggered imaging with newer contrast agents have made myocardial perfusion imaging potentially practical in the very near future. The application of indicator dilution theory to the coronary circulation and bubble contrast agents is fraught with complexities and sources of error. Therefore, quantification of myocardial perfusion by non-invasive echocardiographic imaging requires further investigation in order to make this technique clinically viable.

Comparison of tissue harmonic imaging with contrast (sonicated albumin echocardiography and Doppler myocardial imaging for enhancing endocardial border resolution.

Endocardial resolution during 2-dimensional echocardiography is technically limited in at least 10% to 15% of patients. Recently, several ultrasound imaging innovations have been introduced that may improve endocardial resolution and decrease the proportion of technically difficult studies. This study compares tissue harmonic imaging, intravenous sonicated albumin, and Doppler myocardial imaging in patients with technically difficult echocardiograms. Twenty-eight patients with known or suspected cardiac disease and poor baseline endocardial resolution were studied. Only harmonic imaging (conventional and optimized for tissue) was superior to baseline fundamental imaging (p <0.001). Harmonic imaging was superior to baseline imaging in all myocardial regions and in the majority of patients, including those with the worst baseline studies.

Tissue harmonic imaging: why does it work?

The recent utilization of harmonic frequencies in the imaging of both tissue and contrast agents has dramatically improved echocardiographic image quality. In contrast harmonics, the harmonic frequency energy is generated on reflection from the microbubble contrast agent. In tissue harmonics, the harmonic frequency energy is generated gradually as the ultrasonic wave propagates through the tissue. Critical to the utility of tissue-generated harmonic frequencies is their origin beyond the chest wall and their nonlinear relation to the fundamental frequency energy strength. These two characteristics of tissue-generated harmonics ensure that the echoes most likely to produce artifact are least likely to produce harmonic waves. Armed with an understanding of how these images are produced and with data emerging as to their clinical utility, we anticipate that harmonic imaging will become the standard for assessing regional and global left ventricular function in technically difficult studies.

Outcomes and cost implications of a clinical-based algorithm to guide the discriminate use of stress imaging before noncardiac surgery.

Approximately 8 million patients at risk for coronary artery disease undergo noncardiac surgery annually in the United States. This study defined the appropriateness and cost of evaluating these patients with stress imaging tests. Before noncardiac surgery, 178 consecutive patients were prospectively studied by stress imaging. Pretest cardiac risk (low, intermediate, high) was established by interviewing the referring physician and separately by a cardiologist on the basis of the nature of noncardiac surgery and Eagle's clinical criteria. Patients were followed-up for alterations in management and perioperative events until hospital discharge. Referring physicians and cardiologists identified low risk in 24% and 54% of patients, respectively (p < 0.0001). Of 96 patients identified as low risk by cardiologists, 75 had minor surgery and 21 had major surgery, but no clinical risk factors. In the remaining 82 patients with major surgery, ischemia and other severe abnormalities were detected in 19 (23%) patients. At follow-up, no perioperative complications occurred in minor surgery; one patient with major surgery but no clinical risk factors died from complications related to hypertrophic cardiomyopathy. Patients with at least one clinical risk factor undergoing major surgery but who did not have ischemia on stress testing (n = 63) had two complications (infarction and unstable angina). Intervention (revascularization and surgical cancellation) was probably the explanation for the absence of events in 19 patients with ischemia. With a weighted mean Medicare reimbursement ($386), the use of a simple selection algorithm based on noncardiac surgery and clinical risk to avoid testing low-risk patients would have an average cost of $214 per patient, representing a 45% savings.

Evaluation of left atrial appendage anatomy and function in recent-onset atrial fibrillation by transesophageal echocardiography.

Data regarding left atrial (LA) and LA appendage anatomy and function among patients with newly recognized atrial fibrillation (AF) who have not received long-term warfarin are currently unknown. To identify echocardiographic indexes which characterize those at increased risk for thrombus formation, we analyzed transesophageal echocardiographic studies in 100 consecutive patients with newly recognized AF (duration 2.6 +/- 0.3 week) who had not received long-term warfarin. Fourteen percent of patients had LA thrombi. LA thrombi were associated with larger LA appendages, more depressed LA appendage outflow velocities, and a higher prevalence of severe spontaneous LA contrast. Patients with spontaneous contrast had larger LA and LA appendage anatomy and lower LA appendage ejection velocity. Among patients presenting with their first episode of AF, greater LA appendage ejection and filling velocities and smaller LA and LA appendage sizes were seen among those with AF of <2 weeks duration compared with those with AF of >2 weeks. Thus, patients with recent onset AF and LA thrombi or spontaneous echo contrast have more dilated LA and LA appendage anatomy, and more depressed LA appendage systolic function. Data from patients with their first episode of AF suggests that AF is associated with rapid LA remodeling.