Body surface mapping using an ECG belt to characterize electrical heterogeneity for different left ventricular pacing sites during cardiac resynchronization: Relationship with acute hemodynamic improvement.

BACKGROUND: Electrical heterogeneity (EH) during cardiac resynchronization therapy may vary with different left ventricular (LV) pacing sites. OBJECTIVE: The purpose of this study was to evaluate the relationship between such changes and acute hemodynamic response (AHR). METHODS: Two EH metrics-standard deviation of activation times and mean left thorax activation times-were computed from isochronal maps based on 53-electrode body surface mapping during baseline AAI pacing and biventricular (BiV) pacing from different pacing sites in coronary veins in 40 cardiac resynchronization therapy-indicated patients. AHR at different sites was evaluated by invasive measurement of LV-dp/dtmax at baseline and BiV pacing, along with right ventricular (RV)-LV sensing delays and QRS duration. RESULTS: The site with the greatest combined reduction in standard deviation of activation times and left thorax activation times from baseline to BiV pacing was hemodynamically optimal (defined by AHR equal to, or within 5% of, the largest dp/dt response) in 35 of 40 patients (88%). Sites with the longest RV-LV and narrowest paced QRS were hemodynamically optimal in 26 of 40 patients (65%) and 28 of 40 patients (70%), respectively. EH metrics from isochronal maps had much better accuracy (sensitivity 90%, specificity 80%) for identifying hemodynamically responsive sites (∆LV dp/dtmax ≥10%) compared with RV-LV delay (69%, 85%) or paced QRS reduction (52%, 76%). Multivariate prediction model based on EH metrics showed significant correlation (R2 = 0.53, P <.001) between predicted and measured AHR. CONCLUSION: Changes in EH from baseline to BiV pacing more accurately identified hemodynamically optimal sites than RV-LV delays or paced QRS shortening. Optimization of LV lead location by minimizing EH during BiV pacing, based on body surface mapping, may improve CRT response.

The Proliferative Activity of Mammary Epithelial Cells in Normal Tissue Predicts Breast Cancer Risk in Premenopausal Women.

The frequency and proliferative activity of tissue-specific stem and progenitor cells are suggested to correlate with cancer risk. In this study, we investigated the association between breast cancer risk and the frequency of mammary epithelial cells expressing p27, estrogen receptor (ER), and Ki67 in normal breast tissue. We performed a nested case-control study of 302 women (69 breast cancer cases, 233 controls) who had been initially diagnosed with benign breast disease according to the Nurses' Health Studies. Immunofluorescence for p27, ER, and Ki67 was performed on tissue microarrays constructed from benign biopsies containing normal mammary epithelium and scored by computational image analysis. We found that the frequency of Ki67(+) cells was positively associated with breast cancer risk among premenopausal women [OR = 10.1, 95% confidence interval (CI) = 2.12-48.0]. Conversely, the frequency of ER(+) or p27(+) cells was inversely, but not significantly, associated with subsequent breast cancer risk (ER(+): OR = 0.70, 95% CI, 0.33-1.50; p27(+): OR = 0.89, 95% CI, 0.45-1.75). Notably, high Ki67(+)/low p27(+) and high Ki67(+)/low ER(+) cell frequencies were significantly associated with a 5-fold higher risk of breast cancer compared with low Ki67(+)/low p27(+) and low Ki67(+)/low ER(+) cell frequencies, respectively, among premenopausal women (Ki67(hi)/p27(lo): OR = 5.08, 95% CI, 1.43-18.1; Ki67(hi)/ER(lo): OR = 4.68, 95% CI, 1.63-13.5). Taken together, our data suggest that the fraction of actively cycling cells in normal breast tissue may represent a marker for breast cancer risk assessment, which may therefore impact the frequency of screening procedures in at-risk women. Cancer Res; 76(7); 1926-34. ©2016 AACR.

Ultrasound for routine lumbar puncture.

OBJECTIVES: The objective was to determine if use of ultrasound (US) by emergency physicians (EPs) to localize spinal landmarks improves the performance of lumbar puncture (LP). METHODS: This was a prospective, randomized, controlled study conducted in a county teaching hospital. Subjects, adults 18 years of age or older who were to receive LPs for routine clinical care in the emergency department (ED), were randomized either to undergo US localization of the puncture site or to have the puncture site determined by palpation of spinal landmarks. Primary outcomes were the number of needle insertion attempts and success of the procedure. Secondary outcomes were pain associated with the procedure, time to perform the procedure, number of traumatic taps, and patient satisfaction with the procedure. RESULTS: One-hundred patients were enrolled in the study, with 50 in each study group. There were no significant differences between the two groups in terms of age, sex, body mass index (BMI), indication for LP, or ease of palpation of landmarks. For both primary outcomes and secondary outcomes there were no significant differences between those undergoing US localization and those with palpation alone. CONCLUSIONS: These data do not suggest any advantage to the routine use of US localization for LP insertion, although further study may be warranted to look for benefit in the difficult to palpate or obese patient subgroups.

Transcription factor genes Smad4 and Gata4 cooperatively regulate cardiac valve development. [corrected]

We report that the dominant human missense mutations G303E and G296S in GATA4, a cardiac-specific transcription factor gene, cause atrioventricular septal defects and valve abnormalities by disrupting a signaling cascade involved in endocardial cushion development. These GATA4 missense mutations, but not a mutation causing secundum atrial septal defects (S52F), demonstrated impaired protein interactions with SMAD4, a transcription factor required for canonical bone morphogenetic protein/transforming growth factor-ß (BMP/TGF-ß) signaling. Gata4 and Smad4 genetically interact in vivo: atrioventricular septal defects result from endothelial-specific Gata4 and Smad4 compound haploinsufficiency. Endothelial-specific knockout of Smad4 caused an absence of valve-forming activity: Smad4-deficient endocardium was associated with acellular endocardial cushions, absent epithelial-to-mesenchymal transformation, reduced endocardial proliferation, and loss of Id2 expression in valve-forming regions. We show that Gata4 and Smad4 cooperatively activated the Id2 promoter, that human GATA4 mutations abrogated this activity, and that Id2 deficiency in mice could cause atrioventricular septal defects. We suggest that one determinant of the phenotypic spectrum caused by human GATA4 mutations is differential effects on GATA4/SMAD4 interactions required for endocardial cushion development.

Genome-wide identification of mouse congenital heart disease loci.

Empirical evidence supporting a genetic basis for the etiology of congenital heart disease (CHD) is limited and few disease-causing mutations have been identified. To identify novel CHD genes, we performed a forward genetic screen to identify mutant mouse lines with heritable CHD. Lines with recessive N-ethyl-N-nitrsourea-induced CHD-causing mutations were identified using a three-generation backcross. A hierarchical screening protocol was used to test the hypothesis that the fetal-to-neonatal circulatory transition unmasks the specific structural heart defects observed in CHD. Mice with heart defects were efficiently ascertained by selecting for pups exhibiting perinatal lethality and characterizing their cardiac pathology. A marked increase of perinatal lethality was observed in the mutagen-treated cohort compared with an untreated backcross population. Cardiac pathology on perinatal lethals revealed cardiovascular defects in 79 pups from 47 of 321 mutagenized lines. All identified structural abnormalities were analogous to previously described forms of human CHD. Furthermore, the phenotypic recurrence and variance patterns across all lines were similar to human CHD prevalence and recurrence patterns. We mapped the locus responsible for heritable atrioventricular septal defects in six lines (avc1-6). Our screen demonstrated that 'sporadic' CHD may have major genetic component and established a practical, efficient approach for identifying CHD candidate genes.

sonic hedgehog is required in pulmonary endoderm for atrial septation.

The genesis of the septal structures of the mammalian heart is central to understanding the ontogeny of congenital heart disease and the evolution of cardiac organogenesis. We found that Hedgehog (Hh) signaling marked a subset of cardiac progenitors specific to the atrial septum and the pulmonary trunk in the mouse. Using genetic inducible fate mapping with Gli1(CreERT2), we marked Hh-receiving progenitors in anterior and posterior second heart field splanchnic mesoderm between E8 and E10. In the inflow tract, Hh-receiving progenitors migrated from the posterior second heart field through the dorsal mesocardium to form the atrial septum, including both the primary atrial septum and dorsal mesenchymal protrusion (DMP). In the outflow tract, Hh-receiving progenitors migrated from the anterior second heart field to populate the pulmonary trunk. Abrogation of Hh signaling during atrial septal progenitor specification resulted in atrial and atrioventricular septal defects and hypoplasia of the developing DMP. Hedgehog signaling appeared necessary and sufficient for atrial septal progenitor fate: Hh-receiving cells rendered unresponsive to the Hh ligand migrated into the atrium in normal numbers but populated the atrial free wall rather than the atrial septum. Conversely, constitutive activation of Hh signaling caused inappropriate enlargement of the atrial septum. The close proximity of posterior second heart field cardiac progenitors to pulmonary endoderm suggested a pulmonary source for the Hh ligand. We found that Shh is required in the pulmonary endoderm for atrial septation. Therefore, Hh signaling from distinct pulmonary and pharyngeal endoderm is required for inflow and outflow septation, respectively. These data suggest a model in which respiratory endoderm patterns the morphogenesis of cardiac structural components required for efficient cardiopulmonary circulation.

A molecular pathway including Id2, Tbx5, and Nkx2-5 required for cardiac conduction system development.

The cardiac conduction system is an anatomically discrete segment of specialized myocardium that initiates and propagates electrical impulses to coordinate myocardial contraction. To define the molecular composition of the mouse ventricular conduction system we used microdissection and transcriptional profiling by serial analysis of gene expression (SAGE). Conduction-system-specific expression for Id2, a member of the Id gene family of transcriptional repressors, was identified. Analyses of Id2-deficient mice demonstrated structural and functional conduction system abnormalities, including left bundle branch block. A 1.2 kb fragment of the Id2 promoter proved sufficient for cooperative regulation by Nkx2-5 and Tbx5 in vitro and for conduction-system-specific gene expression in vivo. Furthermore, compound haploinsufficiency of Tbx5 and Nkx2-5 or Tbx5 and Id2 prevented embryonic specification of the ventricular conduction system. We conclude that a molecular pathway including Tbx5, Nkx2-5, and Id2 coordinates specification of ventricular myocytes into the ventricular conduction system lineage.

Bedside ultrasound for difficult lumbar puncture.

Lumbar puncture is a common procedure performed in the emergency department for evaluation of several life-threatening conditions, including meningitis and subarachnoid hemorrhage. We describe the use of bedside ultrasound to assist in performance of the lumbar puncture in situations where the standard "blind" technique of needle insertion using palpable spinal landmarks is likely to be difficult or to fail. Use of ultrasound to guide lumbar puncture needle placement was originally reported 30 years ago in the Russian literature. More recently, ultrasound has been used for guiding needle placement for epidural and spinal anesthesia by anesthesiologists and for diagnostic lumbar puncture on infants by radiologists.

Hydrogen sulfide consumption measured at low steady state concentrations using a sulfidostat.

Although >10 microM hydrogen sulfide typically is toxic to eukaryotic cells, <1 microM sulfide is rapidly consumed and oxidized. To measure sulfide consumption in such low concentrations, we built a "Sulfidostat." The apparatus uses a sulfide-specific electrode to measure the concentration of free sulfide. The electrode is connected to a computer that controls a syringe pump. The pump injects Na(2)S solution into the sample chamber to maintain a constant concentration. Since the response of the electrode to low sulfide concentrations at neutral pH had not been previously validated, that was measured. Then using the Sulfidostat, the rate of sulfide consumption is the rate at which it is pumped into the sample to maintain a constant concentration. The protozoan Tetrahymena pyriformis was used to demonstrate the apparatus; maximum sulfide consumption occurred near 0.5 microM sulfide at a rate of 250 nmol (g protein)(-1) s(-1). That is higher than the rate calculated from the disappearance of sulfide following a bolus addition, a difference that can be explained by the slow response of the electrode and by reversible binding of sulfide by the cells. The Sulfidostat can measure sulfide consumption at concentrations lower than previously have been possible.

Impact of normalized myocardial perfusion after successful angioplasty in acute myocardial infarction.

OBJECTIVES: We sought to evaluate and validate the ability of the angiographic myocardial blush grade to risk stratify patients after successful angioplasty in acute myocardial infarction (AMI). BACKGROUND: Although epicardial Thrombolysis In Myocardial Infarction (TIMI)-3 flow is restored in >90% of patients undergoing primary percutaneous coronary intervention (PCI), normal myocardial perfusion may be present less frequently and may detrimentally impact survival. METHODS: A cohort of 173 consecutive patients undergoing intervention within 24 h of AMI onset were studied. High-risk features of this population included failed thrombolysis in 39%, cardiogenic shock in 17% and saphenous vein graft culprit in 11% of patients. RESULTS: Despite the restoration of TIMI-3 flow in 163 (94.2%) patients, myocardial perfusion, as evidenced by normal contrast opacification of the myocardial bed subtended by the infarct artery (myocardial blush), was normal in only 29.4% of patients with TIMI-3 flow following PCI, and in no patient with TIMI 0 to 2 flow. In patients in whom TIMI-3 flow was restored, survival was strongly dependent on the myocardial perfusion grade; one-year cumulative mortality was 6.8% with normal myocardial blush, 13.2% with reduced myocardial blush and 18.3% in patients with absent myocardial blush (p = 0.004). CONCLUSIONS: Abnormal myocardial perfusion is present in most patients following primary or rescue PCI in AMI, despite restoration of brisk epicardial coronary flow. In high risk patients achieving TIMI-3 flow after intervention, the myocardial blush score may be used to stratify prognosis into excellent, intermediate and poor survival. Further study is warranted to examine whether adjunctive mechanical or pharmacologic strategies can further improve myocardial perfusion and survival of patients with acute myocardial infarction undergoing intervention.

The Principle of Maximum Chiral Discrimination: Chiral Recognition in Permethyl-beta-cyclodextrin.

Five guest molecules, isomenthone, pulegone, 1-fluoro-1-phenylethane, 1-phenylethanol, and 2-methylbutanoic acid, binding to permethyl-beta-cyclodextrin, a chiral host molecule, have been simulated by molecular dynamics techniques. From the simulations we find the preferred binding site to be the interior of the macrocyclic cavity. A new technique was used for locating the host's most enantiodiscriminating domain, which was also found to be inside the macrocyclic cavity. It is concluded that this particular host molecule displays its enhanced chiral discriminating capacity because of this spatial coincidence. Also evaluated in this paper are the types and magnitudes of intermolecular forces responsible for diastereomeric complexation and chiral discrimination; in both cases the short-range dispersion forces dominate. This study illustrates the "principle of maximum chiral recognition", the idea that maximum chiral recognition can be achieved by maintaining a spatial congruence between the host's domain of greatest enantiodifferentiation with the guest's preferred binding site.