Atrial Pacing Lead Location Alters the Hemodynamic Effects of Atrial-Ventricular Delay in Dogs with Pacing Induced Cardiomyopathy

HETTRICK, D.A., et al .: Atrial Pacing Lead Location Alters the Hemodynamic Effects of Atrial Ventricular Delay in Dogs with Pacing Induced Cardiomyopathy. The role of atrial lead location in cardiovascular function in the presence of impaired ventricular dysfunction is unknown. We tested the hypothesis that left atrial (LA) and left ventricular (LV) hemodynamics are affected by alterations in AV delay and are influenced by atrial pacing site in dogs with dilated cardiomyopathy. Dogs   (n = 7)   were chronically paced at 220 beats/min for 3 weeks to produce cardiomyopathy and then instrumented for measurement of LA, LV end diastolic pressure (LVEDP) and mean arterial pressure (MAP), LA volume, LV short-axis diameter, and aortic and pulmonary venous blood flow. Hemodynamics were measured after instrumentation and during atrial overdrive pacing from the right atrial appendage (RAA), coronary sinus ostium (CSO) and lower LA lateral wall (LAW). The AV node was then ablated, and hemodynamics were compared during dual chamber AV pacing (right ventricular apex) from each atrial lead location at several AV delays between 20 and 350 ms. Atrial overdrive pacing from different sites did not alter hemodynamics. Cardiac output (CO), stroke volume, LVEDP, MAP and +dLVP/dt demonstrated significant (P < 0.05) variation with AV delay during dual chamber pacing. CO was higher during LAW pacing than RAA and CSO pacing (   2.3 ± 0.4   vs   2.1 ± 0.3   vs   2.0 ± 0.3 l/min   , respectively) at an AV delay of 120 ms. Also, MAP was higher in the LAW than RAA and CSO (   65 ± 9   vs   59 ± 9   vs   54 ± 11 mmHg   , respectively) at an AV delay of 350 ms. Atrial lead location affects indices of LV performance independent of AV delay during dual chamber pacing in dogs with cardiomyopathy. (PACE 2003; 26[Pt. I]:853–861)     

Initial Experience with a Co-Radial Bipolar Pacing Lead

A new type of endocardial bipolar pacing lead has been designed to overcome the potential drawbacks of the conventional coaxial bipolar pacing had. We prospectively evaluated the new co-radial bipolar pacing leads (Intermedics Thin Line), which are thinner (5 Fr vs 6—8 Fr) than standard coaxial bipolar leads. X-ray visibility and lead handling were subjectively assessed (excellent, good, adequate, or poor) at implant; lead impedance, sensitivity threshold, and pacing threshold were measured at implant, then at 1, 3. 6, 12, and 18 months. The results were as follows: 103 patients (51 M; age 63.8 ± 17.4 years) received 71 atrial (A) and 89 ventricular (V) leads. X-ray visibility was excellent in 59/103; good in 23/103; adequate in 11/103; and poor in 10/103. Overall handling was excellent in 56/71 A and 69/89 V; good in 11/71 A and 18/89 V; adequate in 3/71 A and 1/89 V; poor in 1/71 A and 1/89 V. There were two perioperative complications. At implant: impedance in A and V were 370.1 ± 74.7 and 501.5 ± 124.4 Ω, sensing thresholds in A and V were 3.0 ± 1.5 and 9.9 ± 5.0 mV, pacing thresholds at 0.45 ms in A and V were 0.59 ± 0.21 and 0.41 ± 0.15 volt, respectively. At 1, 3, 6. 12, and 18 months of follow-up: no pacing lead related complications were reported; pacing lead characteristics remained outstanding and stable. This new lead appears to have significant clinical advantages over the conventional coaxial bipolar pacing lead. Long-term follow-up is required to confirm its reliability and chronic performance characteristics.     

Scale development in zebrafish (Danio rerio)

In the course of an extensive comparative, structural and developmental study of the cranial and postcranial dermal skeleton (teeth and scales) in osteichthyan fishes, we have undertaken investigations on scale development in zebrafish (Danio (Brachydanio) rerio) using alizarin red staining, and light and transmission electron microscopy. The main goal was to know whether zebrafish scales can be used as a model for further research on the processes controlling the development of the dermal skeleton in general, especially epithelial–mesenchymal interactions. Growth series of laboratory bred specimens were used to study in detail: (1) the relationship of scale appearance with size and age; (2) the squamation pattern; and (3) the events taking place in the epidermis and in the dermis, before and during scale initiation and formation, with the aim of searching for morphological indications of epithelial-mesenchymal interactions. Scales form late in ontogeny, generally when zebrafish are more than 8.0 mm in standard length. Within a population of zebrafish of the same age scale appearance is related to standard length, but when comparing populations of different age the size of the fish at scale appearance is also related to age. Scales always appear first in the posterior region of the body and the squamation then extends anteriorly. Scales develop in the dermis but closely apposed to the epidermal–dermal boundary. Cellular modifications occurring in the basal layer of the epidermis and in the dermis before scale formation clearly indicate that the basal epidermal cells differentiate first, before any evidence of differentiation of the progenitors of the scale-forming cells in the dermis. This strongly suggests that scale differentiation could be initiated by the epidermal basal layer cells which probably produce a molecular signal towards the dermis below. Subsequently dermal cells accumulate close to the epidermis, and differentiate to form scale papillae. The late formation of the scales during ontogeny is due to a late colonisation of the dermis by the progenitors of the scale-forming cells. Because of their late formation during ontogeny and of their regular pattern of development, scales in zebrafish represent a good model for further investigations on the general mechanisms of epithelial-mesenchymal interactions during dermal skeleton development, and in particular for the study of the gene expression patterns.     

Acute pulmonary oedema following repair of congenital diaphragmatic hernia

Re-expansion pulmonary oedema is a rare form of pulmonary oedema, due to an increased capillary permeability, and is considered to be a reoxygenation injury. The first reported case of the occurrence of a re-expansion pulmonary oedema following the surgical treatment of a congenital diaphragmatic hernia in a young, healthy, 6-year-old child is described.     

Lichenoid tattoo reactions

Two young men, tattooed early in 1977 by the same London tattooist, both rapidly developed lichenoid lesions confined entirely to the red dyed areas.     

URINARY GLYCOSAMINOGLYCAN EXCRETION IN SYSTEMIC SCLEROSIS SUBSETS COMPARED WITH NORMAL CONTROLS

Urinary glycosaminoglycan (GAG) excretion was studied in 30patients with established systemic sclerosis and compared with30 normal controls. There was no significant difference in excretionvalues in the patient group as a whole, but in the group definedas ‘incomplete CREST’ urinary GAG values were lowerthan the group with ‘diffuse disease’ and controls. KEY WORDS: CREST, Proteoglycans     

Studies on Congenital Hemolytic Syndromes. IV. Gastrointestinal Absorption of Iron

1. Results of studies of gastrointestinal absorption of ferrous iron in normalchildren and those with heterozygous thalassemia were similar.

2. In one patient with absent erythropoiesis but severe anemia, no increasein the amount of iron absorbed was noted.

3. In sickle cell-hemoglobin C disease and hereditary spherocytosis havingonly slight anemia in the presence of increased erythropoiesis, normal amountsof iron were absorbed.

4. Patients with sickle cell anemia and thalassemia major in whom therewas active erythropoiesis and marked anemia absorbed abnormally largeamounts of iron. The amount absorbed by individuals with the latter diseasecould be reduced by administration of transfusions and concomitant suppression of erythropoiesis.

5. Usual values for serum iron and latent iron-binding capacity in severalcongenital hemolytic syndromes have been presented and their significancediscussed.

6. No specific effect on absorption was noted by increased or reducedamounts of tissue or serum iron or by reduced or increased latent iron-bindingprotein.

Submitted on June 20, 1961 Accepted on October 30, 1961