Noninvasive neuromodulation and thalamic mapping with low-intensity focused ultrasound.

OBJECTIVE Ultrasound can be precisely focused through the intact human skull to target deep regions of the brain for stereotactic ablations. Acoustic energy at much lower intensities is capable of both exciting and inhibiting neural tissues without causing tissue heating or damage. The objective of this study was to demonstrate the effects of low-intensity focused ultrasound (LIFU) for neuromodulation and selective mapping in the thalamus of a large-brain animal. METHODS Ten Yorkshire swine ( Sus scrofa domesticus) were used in this study. In the first neuromodulation experiment, the lemniscal sensory thalamus was stereotactically targeted with LIFU, and somatosensory evoked potentials (SSEPs) were monitored. In a second mapping experiment, the ventromedial and ventroposterolateral sensory thalamic nuclei were alternately targeted with LIFU, while both trigeminal and tibial evoked SSEPs were recorded. Temperature at the acoustic focus was assessed using MR thermography. At the end of the experiments, all tissues were assessed histologically for damage. RESULTS LIFU targeted to the ventroposterolateral thalamic nucleus suppressed SSEP amplitude to 71.6% ± 11.4% (mean ± SD) compared with baseline recordings. Second, we found a similar degree of inhibition with a high spatial resolution (∼ 2 mm) since adjacent thalamic nuclei could be selectively inhibited. The ventromedial thalamic nucleus could be inhibited without affecting the ventrolateral nucleus. During MR thermography imaging, there was no observed tissue heating during LIFU sonications and no histological evidence of tissue damage. CONCLUSIONS These results suggest that LIFU can be safely used to modulate neuronal circuits in the central nervous system and that noninvasive brain mapping with focused ultrasound may be feasible in humans.

Coronary stent implantation technique: prolonged inflation time maximizes stent expansion.

OBJECTIVES: To determine whether longer periods of stent balloon inflation result in greater minimal luminal diameter (MLD) as measured by quantitative coronary analysis (QCA), and to determine whether measured size correlated with that predicted by pressure-diameter nomograms. METHODS: Seventy-four stents were implanted in 52 patients. Stent acquisitions at a steady inflation pressure were taken at 10 s, 30 s, and 60 s. The stent MLD at each of these intervals was measured by QCA. Comparisons were made between (1) stent diameter obtained at these time intervals; and (2) nomogram-predicted pressure-related stent diameters. RESULTS: Measured stent size increased significantly between each time point measured, with the most marked increment in size (0.15 ± 0.02 mm) observed between 10 s and 30 s (P<.0001), with a smaller but still significant increment between 30 s and 60 s (0.06 ± 0.02 mm; P=.0034). Although there was good correlation between measured size and expected size at 10 s and 30 s (r² = 0.60 and 0.58, respectively), the correlation at 60 s inflation was strongest (r² = 0.65). CONCLUSIONS: Longer durations of stent inflation increase MLD. A minimum duration of 30 seconds is recommended. However, even after 60 s, the MLD does not match the nomogram-derived expected diameter.

Prospective peer review of regional percutaneous interventional procedures: a tool for quality control and revalidation.

AIMS: Current quality measures of percutaneous coronary intervention (PCI) procedures are based on the incidence of major adverse cardiac events (MACE). This crude marker ignores the many clinical nuances that make for sound decision making in PCI. We have established a prospective peer review audit tool to determine the quality of PCI within our cardiac network, which consists of five PCI hospitals serving a population of 1.4 million people in Sussex, UK. METHODS AND RESULTS: Analysis of 10% of all PCI cases selected at random each month by a non-clinical audit manager is made by a rotating panel of two PCI operators and one cardiac surgeon. Each PCI case is assessed for anatomical suitability, lesion severity, strategic appropriateness and final outcome. Panel findings were reported back to the operator and the audit manager. A total of 326 cases were assessed by the review committee. Results were disseminated to individual operators. Coronary anatomy and lesion severity were considered appropriate for PCI in 94.2% and 96.0% of cases, respectively. Appropriateness of strategy was confirmed in 86.2% and the outcome considered satisfactory in 90.8%. A total of 242 subsequent cases were analysed to assess practice trends. This analysis demonstrated a statistically significant improvement in clinical decision making with respect to appropriateness of strategy (from 86.2% to 92.6%; p=0.004). CONCLUSIONS: Prospective peer review of percutaneous coronary intervention cases by a rotating regional committee is valuable in ensuring procedural quality.

Economic analysis of the use of coronary calcium scoring as an alternative to stress ECG in the non-invasive diagnosis of coronary artery disease.

OBJECTIVE: To conduct an economic analysis (EA) of coronary calcium scoring (CCS) using a 0 score, as alternative to stress electrocardiography (sECG) in diagnosing coronary artery disease (CAD). METHOD: A decision tree was constructed to compare four strategies for investigation of suspected CAD previously assessed in the formulation of clinical guidelines for the United Kingdom (UK) to two new strategies incorporating CCS. Sensitivity (96%; 95% CI 95.4-96.4%) and specificity (40%; 95% CI 38.7-41.4%) values for CCS were derived from a meta-analysis of 10,760 patients. Other input variables were obtained from a previous EA and average prices for hospital procedures in the UK. A threshold of £30,000/Quality-adjusted Life Year (QALY) was considered cost-effective. RESULTS: Using net monetary benefit calculations, CCS-based strategies were found to be cost-effective compared to sECG equivalents at all assessed prevalence of CAD. Using CCS prior to myocardial perfusion scintigraphy (MPS) and catheter angiography (CA) was found to be cost-effective at pre-test probabilities (PTP) below 30%. CONCLUSIONS: Adoption of CCS as an alternative to sECG in investigating suspected stable angina in low PTP population (<30%) would be cost-effective. In patients with PTP of CAD >30%, proceeding to MPS or CA would be more cost-effective than performing either CCS or sECG. KEY POINTS: Coronary calcium scoring (CCS) is useful for assessing coronary artery atherosclerosis It can be performed with multi-detector CT, which is now widely available It plays a role in excluding disease in suspected stable angina Our study assesses its role in this setting as alternative to stress-ECG Adoption of CCS as an alternative to sECG could prove cost-effective.

Rescue angioplasty for failed fibrinolysis--long-term follow-up of a large cohort.

BACKGROUND: Fibrinolysis remains an important treatment for ST-elevation myocardial infarction, but fails to achieve adequate reperfusion in a significant proportion of cases. "Rescue" angioplasty is seen as the preferred treatment strategy in most contemporary centers although the literature provides conflicting evidence. METHODS: We retrospectively reviewed all cases of rescue angioplasty performed at our cardiothoracic center from July 1999 to June 2008. The diagnosis of failed lysis was made on the basis of an ECG demonstrating failure of ST segment resolution >50% at 90 min. Periprocedural data was taken from a dedicated procedural database and mortality data obtained from the UK Office of National Statistics. RESULTS: A total of 316 cases were performed. Patients were aged 61 ± 11 years. Thirty-day mortality was 8.9%. Thirty-day mortality in those presenting with cardiogenic shock was 50%, and in those requiring blood transfusion was also 50%. Thirty day mortality in those with TIMI III flow at the end of the procedure was significantly less than in those in whom this was not the case (6.6% vs. 23.3%; P < 0.001). One year mortality for the entire cohort was 10.1%. Longer-term follow-up revealed after 5.2 ± 2.3 years, survival in this cohort was 83%. Significant bleeding requiring blood transfusion occurred in 2.5% of cases. CONCLUSIONS: We have shown that rescue angioplasty can be performed with good procedural success rates and excellent long-term results. Limiting bleeding complications and achieving TIMI III flow appear to be major determinants of achieving good long term results.