Selective pacing sites.

he right ventricular apex (RVA) has always been the most used pacing site, because it is easily accessible and provides a stable lead position with a low dislodgment rate. However, it is well-known that long-term right ventricular apical pacing may have deleterious effects on left ventricular function by inducing a iatrogenic left bundle branch block, which can have strong influences on the left ventricle hemodynamic performances. More specifically, RVA pacing causes abnormal contraction patterns and the consequent dyssynchrony may cause myocardial perfusion defects, histopathological alterations, left ventricular dilation and both systolic and diastolic left ventricular dysfunction. All these long-term changes could account for the higher morbidity and mortality rates observe in patients with chronic RVA pacing compared with atrial pacing. This observation led to the reassessment of traditional approaches and to the research of alternative pacing sites, in order to get to more physiological pattern of ventricular activation and to avoid deleterious effects. Then, attempts were made with: right ventricular outflow tract (RVOT) pacing, direct His bundle pacing (DHBP), parahisian pacing (PHP) and bifocal (RVA + RVOT) pacing. For example, RVOT pacing, especially in its septal portion, is superior to the RVA pacing and it would determine a contraction pattern very similar to the spontaneous one, not only because the septal portions are the first parts to became depolarized, but also for the proximity to the normal conduction system. RVOT is preferable in terms of safety too. DHBP is an attractive alternative to RVA pacing because it leads to a synchronous depolarization of myocardial cells and, therefore, to an efficient ventricular contraction. So it would be the best technique, however the procedure requires longer average implant times and dedicated instruments and it cannot be carried out in patients affected by His bundle pathologies; furthermore, due to the His bundle fibrous area, higher pacing thresholds are required, causing accelerated battery depletion. For all these reasons, PHP could be considered an important alternative to DHBP, to be used on a large scale. Finally, bifocal pacing in CRT candidates, provides better acute hemodynamic performance than RVA pacing, derived from a minor intra- and interventricular dyssynchrony, expressed also by the QRS shortening. Then, bifocal pacing could be taken into account when RVA pacing is likely to be the origin of serious mechanical and electrical dyssynchrony or when CRT is contraindicated or technically impossible. So, whatever chosen as selective pacing site, you must look also at safety, effectiveness and necessary equipment for an optimal pacing site.

Marshall's vein persistence: a rare and occasional finding during pacemaker implantation.

In adults the oblique vein of Marshall is usually absent or very thin, and it is hard to be found. In this case report we describe a case of persistence observed during pacemaker implantation.

Carotid intimal-media thickness and endothelial function in young patients with history of myocardial infarction.

AIM: The aim of the study was to evaluate the prevalence of carotid atherosclerosis and endothelial dysfunction in 45 young patients (38 mens and 7 females) with myocardial infarction (MI), age 29-45, mean age 42+/-3 years, to verify its possible role as a marker of coronary atherosclerosis. METHODS: Vascular echography was performed to verify the presence of carotid atherosclerosis and/or endothelial dysfunction in 45 young patients with MI and in 45 healthy control subjects well matched for age and sex. RESULTS: We observed a normal intima media thickness (IMT) only in 30% of patients with juvenile myocardial infarction (JMI) compared with 66% in the control group (P<0.0001) and 34% of patients showed an increased IMT compared with 24% of healthy subjects (P<0.0001). Compared with control subjects, patients with JMI had lower flow-mediated reactivity of the brachial arteries (P<0.05). There was a negative linear relationship between flow-mediated dilation and IMT (P<0.001). The severity of coronary artery disease (CAD) was correlated with increased IMT and with a lower flow-mediated dilation. Finally, multiple regression analysis, demonstrated that both brachial-artery reactivity and carotid IMT were significantly and independently correlated with severity of CAD. CONCLUSIONS: Structural (carotid atherosclerosis) and functional changes (endothelial dysfunction) were present at an early age in the arteries of persons with history of JMI.

In-hospital stay of patient with acute coronary syndrome with or without diabetes mellitus.

AIM: Type 2 diabetes is associated with an increase in the risk of coronary heart disease, by a factor of two to four. The scientific community has suggested that all patients with diabetes could be treated as if they had a prior coronary heart disease. METHODS: A computer review of 11-year prevalence (from 1991 to 2002) of type 2 diabetes among 3242 patients admitted to the Intensive Coronary Care Unit of the Division of Cardiology of the University Hospital ''Paolo Giaccone'', Palermo, was carried out, with the diagnosis of ST elevation myocardial infarction (STEMI) (51%), non ST elevation myocardial infarction (NSTEMI) (6%) or unstable angina (UA) (43%). RESULTS: Prevalence of type 2 diabetes was 31.5% on the overall population; in particular, a higher prevalence was found among STEMI affected patients (37% of the diabetic patients). The average number of days of an in-hospital stay was of 10.4+/-3.1 for diabetic patients without complications (N.=602) and of 15.9+/-4.4 for diabetic patients with clinical complications (N.=421) as compared with non diabetic patients non complicated (N.=1821) or complicated (N.=398), with an average in-hospital stay of 7.4+/-1 and 12.8+/-3.2 days respectively; P<0.005. CONCLUSIONS: Diabetic patients with acute coronary syndrome had more clinical complications (41.1% vs 17.9%, P=0.0001) and a longer in-hospital stay period, resulting in an increased management costs, in comparison with non diabetic patients.

Short term prognostic role of NT-proBNP in patients after myocardial infarction.

AIM: The clinical and prognostic role of cardiac natriuretic peptides (CNP) in patients with heart failure is well known; recently, several studies have evaluated the possibility of using CNP to evaluate their potential prognostic role in patients with acute coronary syndromes (ACS). The aim of this study was to evaluate the short term prognostic value of NT-proBNP in 70 patients admitted for ACS. METHODS: The authors studied 70 patients with ACS, evaluating, at admission, clinical-anamnestic, instrumental and laboratory characteristics including NT-proBNP plasma levels. Patients were monitored in a 6-month-follow-up to record adverse fatal events and their possible correlation with baseline characteristics. RESULTS: The incidence of adverse events during the follow-up period was 28% (10 patients). In patients with adverse events, the authors observed lower left ventricle ejection fraction (P=0.01), higher prevalence of ST elevation myocardial infarction (P=0.03) and higher NT-proBNP levels (P=0.03), compared to those without adverse events. Moreover, the logistic regression analysis underlined how ST elevation myocardial infarction (P=0.05) and higher NT-proBNP levels (P=0.05) were the only predictive variables for adverse events during the follow up period. CONCLUSIONS: This study demonstrates the short term prognostic role of NT-pro BNP in patients admitted for ACS.

Prognostic role of endothelial dysfunction and carotid intima-media thickness in patients undergoing coronary stent implantation.

AIM: Impaired endothelial function and increased carotid intima-media thickness are key events in the atherosclerotic process and predict future cardiovascular events in subjects with and without coronary artery disease. The purpose of this study was to investigate whether the vasodilator response to increased flow in the brachial artery and the presence of carotid lesions may have a prognostic significance for in-stent restenosis in patients undergoing coronary angioplasty. METHODS: The study population included 58 patients undergoing percutaneous coronary intervention (PCI) with stenting and at least 10 months of follow-up. All patients underwent ultrasound detection of brachial artery reactivity 30 days after PCI. Flow mediated dilatation (FMD) was investigated after 5 minutes of occlusion of the artery and nitroglycerin mediated dilation (NMD) was investigated after administration of sublingual nitrates. Vascular echography was performed to measure intima media thickness (IMT) of carotid arteries. At baseline we evaluated all the established traditional cardiovascular risk factors. We also subdivided our study cohort according to values of FMD in patients with FMD above and patients below the median value. RESULTS: Patients with FMD above the median value showed higher prevalence of hypertension (P=0.002), diabetes (P=0.02) and carotid IMT (P=0.006) than those below the median. Brachial FMD was inversely correlated (P=0.001) to carotid IMT. At the end of follow-up clinical events occurred in nine patients. In a multivariate analysis, including all the variables evaluated at baseline, carotid IMT (P=0.02), level of glycemia (P=0.001), a lower FMD (P=0.005) and presence of carotid plaque remained the only variables predictive of restenosis. CONCLUSIONS: Evaluation of FMD and carotid IMT may provide important prognostic information in patients undergoing PCI.

Carotid and peripheral atherosclerosis in patients who underwent primary percutaneous coronary intervention and outcome associated with multifocal atherosclerosis.

AIM: The aim of our study was to determine if patients with multifocal atherosclerosis have a worse prognosis than patients with atherosclerosis only in the coronary bed. METHODS: We studied 45 subjects admitted to intensive coronary care unit of the Division of Cardiology with the diagnosis of acute myocardial infarction (AMI). Traditional cardiovascular risk factors were investigated and laboratory analysis included measurement of plasma lipids, glycemia, fibrinogen and high-sensitivity-C-reactive protein (hs-CRP). Each patient underwent coronary-angiography as well as carotid and peripheral arterial ultrasound examination. A follow-up of 13+/-2 months was performed. RESULTS: We found that the severity of coronary atherosclerosis is significantly associated with the presence of carotid (P<0.05) and peripheral atherosclerosis (P<0.005). Markers of inflammation, hs-CRP (P<0.005) and fibrinogen (P<0.05), were significantly associated with multifocal atherosclerosis. We have shown that an increased number of coronary vessels with atherosclerotic stenosis is associated with a higher value of carotid (P<0.0001) and peripheral intima media thickness (P<0.0001). During 13 months of follow-up the incidence of fatal or non fatal events was 18%. The multivariate analysis showed that the variables independently associated with fatal and non fatal events were: male sex (P<0.001), family history of cardiovascular disease (P<0.005), hypertension (P<0.01), diabetes mellitus (P<0.05), higher levels of total cholesterol (P<0.05), smoking habit (P<0.05), and multifocal atherosclerosis (P<0.05). CONCLUSIONS: The ultrasound examination of carotid and peripheral atherosclerotic lesions may be useful in placing patients with AMI in a category of higher risk of cerebrovascular and cardiovascular events. Moreover, the precocious identification of patients at risk can suggest a more aggressive pharmacological treatment and a more accurate follow-up in order to avoid future events.

Isolation procedure for bovine retinal rod outer segments.

An isolation procedure to obtain rod outer segments from cattle retinas is reported. Centrifugation of homogenates in discontinuous and continuous sucrose density gradients yields purified photoreceptor cell outer segments. Assay of the final preparation for rhodopsin content gives a ratio of 2.4 for DO280nm/DO498nm.