Pulsation-pressure relationship in experimental aneurysms: Observation of aneurysmal hysteresis

Abstract

In this study the pulsation-pressure relationship in an experimental model of aneurysms was analyzed. In addition, we have examined pulsatility of the aneurysmal wall reinforced by Cuglielmi Detachable Coils (GDC). Bifurcation (BAn), aneurysms (LAn) and bilobar (BiA) aneurysms were produced in 15 mongrel dogs. The aneurysmal dome was constructed from a segment of the external jugular vein which was sutured to the window performed on the' apex of bifurcation of the ECA and lingual artery (BAn) or,on the ECA (LAn). One set of the GDC (diameter 5 mm, length 20 cm) were inserted into the aneurysm. Intra- aneurysmal pressure> aneurysmal pulsation, ECG and femoral artery pressure were recorded. Results showed that an experimental aneurysm pulsates in synchrony with the intraaneurysmal pressure and aneurysmal pulsation is proportional to the aneurysmal size. Pulsation profile also depends on the aneurysmal type (BAn, LAn, BiA). The looped pressure-pulsation curve indicates that aneurysms exhibit property of hysteresis. For the same pressure the aneurysm is smaller during the ascending (systolic) portion of the blood pressure wave. Insertion of catheter into the aneurysm and subsequent release of the GDC did not elicit any measurable changes of the intraaneurysmal pressure. Aneurysm reinforced by GDC showed smaller pulsation and the hysteresis was reduced as well. It was concluded that aneurysmal hysteresis could be an important factor resulting in degeneration of aneurysmal wall since it is known that hysteresis accelerates degeneration of all fibrous elements, predominantly of elastic fibers. GDC seems to buffer the intra-aneurysmal hemodynamic forces and hence they might have a stabilizing effect on the aneurysmal wall. [Neurol Res 1996; 18: 377-382]     

Patent foramen ovale

INTRODUCTION: Intentional or unintentional placement of a pacemaker lead into the left ventricle is an uncommon clinical entity that is associated with a high risk for systemic embolization and enormous difficulties in case of explantation. Unintentional implantation through a patent foramen ovale via the mitral valve is the usual pathway for this malposition. METHODS: We report a case where a pacemaker lead was placed intentionally into the left ventricle via a patent foramen ovale for biventricular pacing for resynchronization therapy. Later, the patient developed life-threatening pacemaker lead-associated endocarditis with sepsis. Emergency open heart surgery for lead removal was necessary in the form of a reoperation after bypass graft surgery a number of years earlier. CONCLUSION: Although it is technically feasible to implant the pacemaker lead into the left ventricle via a patent foramen ovale, we consider this option to be obsolete for use with a biventricular pacemaker, due to the multitude of risks, which can, in part, be life-threatening for the patient.     

Key High‐efficiency Practices of Emergency Department Providers: A Mixed‐methods Study

Objective

The objective of this study was to determine specific provider practices associated with high provider efficiency in community emergency departments (EDs).

Methods

A mixed‐methods study design was utilized to identify key behaviors associated with efficiency. Stage 1 was a convenience sample of 16 participants (ED medical directors, nurses, advanced practice providers, and physicians) identified provider efficiency behaviors during semistructured interviews. Ninety‐nine behaviors were identified and distilled by a group of three ED clinicians into 18 themes. Stage 2 was an observational study of 35 providers was performed in four (30,000‐ to 55,000‐visit) community EDs during two 4‐hour periods and recorded in minute‐by‐minute observation logs. In Stage 3, each behavior or practice from Stage 1 was assigned a score within each observation period. Behaviors were tested for association with provider efficiency (relative value units/hour) using linear univariate generalized estimating equations with an identity link, clustered on ED site.

Results

Five ED provider practices were found to be positively associated with efficiency: average patient load, using name of team member, conversations with health care team, visits to patient rooms, and running the board. Two behaviors, “inefficiency practices,” demonstrated significant negative correlations: non–work‐related tasks and documentation on patients no longer in the ED.

Conclusions

Average patient load, running the board, conversations with team member, and using names of team members are associated with enhanced provider productivity. Identification of behaviors associated with efficiency can be utilized by medical directors, clinicians, and trainees to improve personal efficiency or counsel team members.

     

Hypertension in a Brazilian Urban Slum Population

Low- and middle-income countries account for the majority of hypertension disease burden. However, little is known about the distribution of this illness within subpopulations of these countries, particularly among those who live in urban informal settlements. A cross-sectional hypertension survey was conducted in 2003 among 5649 adult residents of a slum settlement in the city of Salvador, Brazil. Hypertension was defined as either an elevated arterial systolic (≥140 mmHg) or diastolic (≥90 mmHg) blood pressure. Sex-specific multivariable models of systolic blood pressure were constructed to identify factors associated with elevated blood pressure. The prevalence of hypertension in the population 18 years and older was 21 % (1162/5649). Men had 1.2 times the risk of hypertension compared with women (95 % confidence intervals (CI), 1.05, 1.36). Increasing age and lack of any schooling, particularly for women, were also significantly associated with elevated blood pressure (p < 0.05). There was also a direct association between men who were black and an elevated blood pressure. Among those who were hypertensive, 65.5 % were aware of their condition, and only 36.3 % of those aware were actively using anti-hypertensive medications. Men were less likely to be aware of their diagnosis or to use medications (p < 0.01 for both) than women. The prevalence of hypertension in this slum community was lower than reported frequencies in the non-slum population of Brazil and Salvador, yet both disease awareness and treatment frequency were low. Further research on hypertension and other chronic non-communicable diseases in slum populations is urgently needed to guide prevention and treatment efforts in this growing population.     

Polymorphonuclear granulocytes in rheumatic tissue destruction VIII. Considerations on the inflammatory cartilage destruction in chronic arthritides in comparison with liver injuries by PMN's

Inflammatory cartilage destruction in chronic arthritides is usually regarded as the process owing to chondrocytic chondrolysis or ingrowth of pannus tissue. Besides these two mechanisms a third one-cartilage degradation directly mediated by polymorphonuclear granulocytes (PMN's) of the synovial fluid-seems to be underestimated. There is growing evidence that PMN's are involved in several non-bacterial organ destructions (e.g., alcoholic hepatitis); thus, two case reports are presented demonstrating cartilage destruction by PMN's via the synovial fluid. It is shown by light and electron microscopy that in florid rheumatoid arthritis, PMN's from the inflamed synovial fluid can gain access to the cartilaginous surface. The adherence of PMN's to the superficial matrix, eventually mediated by immunocomplexes, may activate these cells with the subsequent secretion of destructive enzymes as well as reactive oxygen species. Cartilage degradation may be the consequence. From the morphological findings it is deduced that this mechanism may have important implications for inflammatory cartilage loss.     

Gene therapy of hepatocellular carcinoma in vitro and in vivo in nude mice by adenoviral transfer of the Escherichia coli purine nucleoside phosphorylase gene

Expression of viral or bacterial enzymes in tumor cells to convert nontoxic prodrugs into highly toxic metabolites is an attractive gene-therapeutic approach for the treatment of hepatocellular carcinoma (HCC). The Escherichia coli purine nucleoside phosphorylase (PNP) converts purine analogs into freely diffusible metabolites, which are highly toxic to dividing and nondividing cells. We investigated the antitumor effects of PNP in the human HCC cell lines, HepG2, Hep3B, and HuH-7, and performed a comparison with herpes simplex thymidine kinase (TK). The genes for PNP, TK, and enhanced green fluorescent protein (EGFP) were delivered to HCC cells by identical adenoviral vectors. Fludarabine and ganciclovir (GCV) served as prodrugs for PNP and TK, respectively. Expression of PNP highly sensitized HCC cells to fludarabine treatment. Fludarabine concentrations between 0.5 and 1 microg/mL killed 100% of the cells expressing PNP with no detectable toxicity in control cells expressing EGFP. Expression of PNP in as few as 10% of HCC cells induced efficient killing of most bystander cells. Expression of TK followed by GCV treatment produced a potent growth inhibition but failed to kill all TK-expressing HCC cells. More importantly, the TK system exhibited a lower degree of bystander effect. Adenoviral delivery of PNP followed by fludarabine administration prevented subcutaneous and intrahepatic tumor formation in nude mice and was also effective for the treatment of established tumors. These results demonstrate the potential of the PNP/fludarabine system for the treatment of HCC.     

Diagnostic value of intraoperative swabs of heart valves in infective endocarditis

BACKGROUND AND AIM OF THE STUDY: Intraoperative swabs of heart valves are obtained regularly from patients undergoing heart valve surgery for infective endocarditis (IE) in order to confirm the preoperative diagnosis and to adjust the antibiotic regimen. The study aim was to assess the diagnostic value of intraoperative swabs of heart valves in IE. METHODS: A total of 83 patients was referred for surgical treatment of active IE between October 1994 and May 1999. Preoperatively, microorganisms were isolated using a minimum of two positive blood cultures; results were compared with those obtained from intraoperative heart valve swab cultures. RESULTS: Preoperatively, 73 patients (88%) had a positive blood culture, and 10 (12%) had culture-negative endocarditis. The intraoperative swab confirmed the preoperative diagnosis in 31 cases (37%). Bacteria were isolated in three of the ten patients with preoperative culture-negative IE. Despite positive histopathological findings in seven patients, no microorganisms were cultured either pre- or intraoperatively. Among the remaining 42 patients (51%) with active IE, 25 valve cultures were sterile and 17 valve swabs were presumed to be contaminated. CONCLUSION: In patients with active IE in whom the causative agent could be isolated and identified before surgery, intraoperative valve swabs did not contribute further to patient management. In isolating contaminants, the risk of inappropriate modification of the antibiotic regimen is imminent. The diagnostic validity in culture-negative IE appears negligible.