A Review of the Recent Advances of Cardiac Pacemaker Technology in Handling Complications.

The total number of annual pacemaker implantations continues to grow globally, and help patients with heart rhythm disorders with an improved quality of life and reduced mortality. The first implantable pacemakers appeared in 1965, characterized by their bulkiness, short battery life, and a single pacing mode. Innovation led to the modern pacemaker: a smaller system with improved battery life and capacity, and innovation in lead technology. Certain arrhythmia conditions may also qualify for leadless pacemaker implantation, thus eliminating the spectrum of complications that could occur with leads. Adverse events can be divided into acute (perforation, lead dislodgement, infection) and long-term (lead fractures, device infection, insulation failure). Traditional long-term complications with leads occur in 10% of patients, compared with device-related adverse effects observed in 6.7% of leadless pacemakers. Furthermore, cardiac pacemaker implantation results in quality of life improvements across all age groups. Large cardiac rehabilitation studies have demonstrated the effectiveness of exercise in reducing the physical complications involved with pacemaker implantation. Of the three randomized controlled trials examined, all of them reported some benefit of exercise in the intervention group compared with the control. The following review aims to discuss the multitude of pacemaker options potentially available for the clinician, complications, their course of management, and the path forward with innovations arising out of previous research within the field.

Early and long-term effects of colectomy and endorectal pullthrough on bile acid profile.

OBJECTIVE: Although total colectomy with mucosal proctectomy and endorectal pullthrough affects two sites critical to the enterohepatic circulation of bile acids, little information is available regarding the manner in which normal digestive physiology is altered by these procedures. This study defines the early and long-term effects of colectomy and endorectal pullthrough on bile acid profile and the long-term effects on biliary lipid metabolism. SUMMARY BACKGROUND DATA: Specific changes in bile acid absorption have been reported in patients after ileal resection. Recent studies from our laboratory indicate that in the early postoperative period, colectomy with endorectal pullthrough causes a significant decrease in gallbladder bile concentrations of total bile acids, cholesterol, phospholipids, and calcium. The observation by several authors that the pouch undergoes morphologic and perhaps functional adaptation suggest that these changes may be transient and perhaps reversible. METHODS: These studies were done in an awake, unanesthetized canine model that allows periodic sampling of gallbladder bile without creation of an external biliary fistula and its associated sequelae. Animals were ultimately randomly assigned to either laparotomy and gallbladder cannulation (N = 6), or gallbladder cannulation with total colectomy and ileorectal anastomosis (N = 7), or biliary cannulation, colectomy, mucosal proctectomy and endorectal pullthrough with ileal reservoir (N = 5). RESULTS: Six weeks after operation, colectomy and ileorectal anastomosis were associated with a significant alteration in the relative composition of bile acids in gallbladder bile. These early changes were manifested by a significant (p < 0.05) increase in taurocholic acid and a concomitant decrease in taurodeoxycholic acid. These changes became even more pronounced in the ileorectal anastomosis group 12 weeks after colectomy and ileorectostomy. Although similar changes in the relative concentrations of individual bile acids occurred in the 6-week endorectal animals, bile acid profile was restored to normal by 12 weeks. CONCLUSIONS: Colectomy with ileorectal anastomosis leads to early and significant changes in bile acid profile, which persist and become even more pronounced with time. In contrast, the construction of an ileal reservoir after colectomy facilitates restoration of a normal bile acid profile. We propose that these alterations in bile acid metabolism result from adaptation of the ileal reservoir as its mucosa assumes functional characteristics of normal colon.

Altered proximal tubule glucose metabolism in X-linked hypophosphatemic mice.

In the present study we examined renal proximal tubule glucose metabolism in the X-linked hypophosphatemic (Hyp/Y) mouse. Compared to those in its normal (+/Y) littermate, Hyp/Y mouse proximal tubules showed a higher rate of glucose production when using glutamine or alpha-ketoglutarate as a substrate. The glucose production rate was not, however, different when using malate or fructose as the substrate. PTH stimulated glucose production in +/Y, but not Hyp/Y, mouse proximal tubules. The PTH resistance in Hyp/Y mouse involves steps at and post-cAMP formation, because in Hyp/Y mouse proximal tubules PTH effects a lesser stimulation of cAMP generation, and addition of 8-bromo-cAMP failed to increase the glucose production rate. The rate of glucose utilization as a whole was not different in the two groups, but the rate of glucose metabolized through the pentose cycle (PC) pathway was markedly lower in Hyp/Y mouse proximal tubules. The lower PC activity in Hyp/Y mouse proximal tubules did not result from a defect of PC enzymes, because both glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase enzyme activities were intact, and phenazine methosulfate was able to stimulate PC activity. The higher rate of glucose production and the lower rate of PC activities persisted in the in vitro cultured Hyp/Y mouse proximal tubular cells. These results suggest that the altered glucose metabolism in the Hyp/Y mouse proximal tubule is not maintained by external influences and may be an abnormality intrinsic to these cells.