Balloon‐Facilitated Delivery of a Left Ventricular Pacing Lead

While modern implant tools have contributed greatly to the success of cardiac resynchronization therapy, technical challenges remain. A common problem is the inability to advance left ventricular pacing leads into branch veins that are tortuous or arise at steep angles. In these cases, advancement of the lead causes it to buckle and prolapse into the coronary sinus or great cardiac vein. Lead prolapsed can be avoided by employing a balloon to temporarily obstruct the coronary sinus or great cardiac vein just upstream from the branch vein. The balloon redirects the force of advancement laterally into the branch vein, facilitating delivery. (PACE 2013; 36:e31–e34)     

Hypersomatostatinaemia in duodenal ulcer

Abstract A sensitive and specific radioimmunoassay of serum somatostatin has been developed that overcomes the problems encountered in earlier assays of peptide disintegration and the need for prior plasma extraction, which is known to result in artifactual loss of somatostatin. In 37 normal controls, a significant positive correlation between fasting serum gastrin and somatostatin concentrations, and a significant negative correlation between pentagastrin-stimulated maximal acid output and fasting serum somatostatin levels were observed. In the majority of 134 patients with active duodenal ulcer in whom the fasting serum somatostatin levels were normal, these relationships were absent. In the remaining 25% in whom the fasting serum somatostatin levels were abnormally raised, these relationships were retained. Following a mixed meal, circulating somatostatin levels remained unchanged in controls and patients as a group. These results suggest that: (i) in the normal state, fasting levels of circulating gastrin and somatostatin are closely related, and that acid secretion may paradoxically exert an inhibitory effect on fasting somatostatin levels; (ii) hypersomatostatinaemia identifies a subgroup of patients with duodenal ulcer in whom these relationships are retained; and (iii) somatostatin may not have a significant hormonal role in the postprandial state in man.     

Clinical and Angiographic Outcomes with Everolimus Eluting Stents for the Treatment of Cardiac Allograft Vasculopathy

Objectives

This study aimed to examine clinical efficacy, safety, and intermediate clinical outcomes with everolimus‐eluting stents (EESs) in patients with transplant coronary artery disease (TCAD).

Background

TCAD is a major cause of mortality in patients following orthotopic heart transplantation (OHT). Systemic everolimus in OHT patients has been shown to reduce TCAD. The safety and efficacy of an EES, the Xience V, have not been evaluated in this population.

Methods

Patients post‐OHT with hemodynamically significant CAD who underwent percutaneous coronary intervention (PCI) with EES were included. Participants were maintained on dual antiplatelet therapy for 1‐year post‐PCI. We examined procedural success, in‐hospital and 1‐year mortality, stent thrombosis, angiographic restenosis, and myocardial infarction rates. All patients had follow‐up angiography 1‐year after PCI. Target vessel revascularization (TVR), target lesion revascularization (TLR), in‐segment restenosis, target vessel failure (TVF), and lumen late loss were noted.

Results

PCI was performed in 34 de novo lesions in 21 patients, and 40 EES were placed. Procedural success rate was 100%. Average stent was 16.5 ± 5.1 mm long and 3.0 ± 0.6 mm in diameter. All patients had angiographic follow‐up (409 ± 201 days). There was no stent thrombosis, deaths, or myocardial infarctions during follow‐up. Two patients had focal in‐stent restenosis. TLR rate was 5.9% (2/34), and TVR rate was 11.1% (3/27). Quantitative coronary angiography (QCA) showed stenosis diameter to be 19.98 ± 17.57%.

Conclusions

Use of an EES is associated with a low incidence of TVR and TLR in patients with TCAD. Further studies are needed to determine whether PCI with EES changes long‐term outcomes. (J Interven Cardiol 2014;27:73–79)

     

Modeling the Interaction Between Propagating Cardiac Waves and Monophasic and Biphasic Field Stimuli:

Field-Induced Excitatory Responses Across Propagating Waves. Introduction: Biphasic (BP) defibrillation waveforms have been shown to be significantly more efficacious than equivalent monophasic (MP) waveforms. However, when defibrillation falls, it tends to do so first in distal regions of the heart where induced field gradient magnitudes are lowest. We tested the hypothesis that the improved efficacy of BP waveforms results from their enhanced ability to prevent the initiation of new postshock activation fronts behind preexisting; wavetails, rather than from any significantly improved ability to terminate preexisting wavefronts. Methods and Results: An idealized computer model of a one-dimensional cardiac strand was used to investigate the spatial and temporal interactions between an underlying propagation front (or tail) and uniform MP or BP field stimuli of various intensities. Axial discontinuities from intercellular junctions induced sawtooth patterns of polarization during such field stimuli, enabling the shocks to interact directly with all cells. MP and BP diastolic thresholds were essentially equal. All suprathreshold MP and BP field stimuli successfully terminated preexisting wavefronts by directly depolarizing tissue ahead of those fronts, thus blocking their continued progression. However, the postshock response at the wavetail was significantly dependent on the shape and strength of the administered field. Low-strength MP stimuli induced an all-or-none excitation response across the wavetail, producing a sharp spatial transmembrane voltage gradient from which a new sustained anterogradely propagating wavefront was initiated. In contrast, low-strength BP field stimuli induced a spatially graded excitatory response whose voltage gradient was insufficient to initiate such a wavefront. Higher-strength MP and BP stimuli both produced graded excitatory responses with no subsequent propagation. Conclusions: Shock-induced spatial “all-or-none” excitatory responses facilitate, and graded excitatory responses prevent, the postshock initiation of new propagating wavefronts. Moreover, BP field stimuli can induce such graded excitatory responses at significantly lower stimulus strengths than otherwise equivalent MP stimuli. Therefore, these results support an alternative “graded excitatory response” mechanism for the improved efficacy of BP over MP field stimuli in low gradient regions.     

Liver stem cells: when the going gets tough they get going

The ability of the liver to regenerate is widely acknowledged, and this is usually accomplished by the entry of normally proliferatively quiescent hepatocytes into the cell cycle. However, when hepatocyte regeneration is impaired, small bile ducts proliferate and invade into the adjacent hepatocyte parenchyma. In humans and experimental animals these ductal cells are referred to as oval cells, and their association with defective regeneration has led to the belief that they are the progeny of facultative stem cells. Oval cells are of great biological interest since they may represent a target population for hepatic carcinogens, and they may also be useful vehicles for ex vivo gene therapy for the correction of inborn errors of metabolism.
The ability of oval cells to differentiate into hepatocytes has been demonstrated unequivocally. However, this process only occurs when the regenerative capacity of hepatocytes is overwhelmed, and thus, unlike the intestinal epithelium, the liver is not behaving as a classical continually renewing stem cell-fed lineage.