T-wave changes in intermittent left bundle branch block. Pathogenesis and clinical significance

In patients with intermittent left bundle branch block (LBBB) it is common to observe T wave abnormalities in the right precordial leads during normally conducted beats. These changes have usually been interpreted as a result of anteroseptal ischemia. More recently it has been suggested that they may be the consequence of an electric phenomena secondary to the abnormal ventricular activation. However, the "benign" character of these abnormalities has never been confirmed by clinical studies. We have studied a group of 10 pts (3 males and 7 females), aging between 23 and 66 years (mean 41 +/- 8) with atypical precordial pain admitted to our institution, because of intermittent LBBB and T wave inversion in the right precordial leads during the normally conducted beats. All patients had normal left ventriculography and coronary angiograms. During the follow-up period (20 to 102 months, mean 4.7 years) they were subjected to serial clinical examinations, 24 hours ECG Holter monitoring echocardiogram and exercise thallium 201 scintigraphy. Within this period of observation, no patient developed symptoms or signs of cardiac involvement while all but three developed a stable LBBB (these three patients have been followed only for a limited period of time). Exercise thallium 201 scintigraphy showed in 4 patients a reversible septal perfusion defect during LBBB. We conclude that T wave abnormalities observed in the normally conducted beats in patients affected by intermittent LBBB have a favourable prognostic significance.(ABSTRACT TRUNCATED AT 250 WORDS)     

Colorectal cancer screening programme by faecal occult blood test in Tuscany: first round results.

Screening with faecal occult blood test (FOBT) has been shown to be effective in reducing mortality from colorectal cancer. Tuscany was the first region in Italy in which a screening programme for colorectal cancer by FOBT was initiated region-wide. The aim of the paper was to describe organizational aspects, a quality control model and the results of this experience. From June 2000 to December 2001, 192583 subjects aged 50-70 were invited to undergo a 1-day immunochemical test without any dietary restriction. A total of 78505 subjects (41%) performed the screening test, of whom 4537 responders had a positive test result (5.8%). Among them, 1122 refused any form of assessment or underwent a colonoscopy outside the screening referral centres, with an overall assessment compliance of 75.3%. Malignancies were found in 193 patients and at least a high-risk adenomatous polyp in 692 patients. In about a quarter of the positive subjects who underwent assessment, cancer or high-risk adenoma was detected. In conclusion, data from this experience supported the feasibility of biennial colorectal screening programme by FOBT, particularly regarding invitation compliance and positivity rate. Further efforts are necessary to implement screening extension and to improve data collection.     

The role of glutathione status in the protection against ischaemic and reperfusion damage: effects of N-acetyl cysteine

It is known that myocardial ischaemia causes a marked decline of cellular thiol pool and of protein sulphydryl groups content. Reperfusion under these conditions results in oxydative damage which is concomitant with poor recovery of mechanical function. We have evaluated the role of glutathione status in the protection against ischaemic and reperfusion damage by treating the isolated rabbit hearts with N-acetylcysteine (10(-6) M), a sulphydryl group donor. Ischaemic and reperfusion damage was determined in terms of mechanical function, rate of lactate and creatine kinase (CPK) release, mitochondrial function and tissue content of reduced (GSH) and oxidized (GSSG) glutathione and of protein sulphydryl groups (SH). After 60 mins of ischaemia (induced by reducing coronary flow from 24 to 1 ml/min) followed by 30 mins of reperfusion there was an increase of diastolic pressure to 51.6 +/- 3.5 mmHg with only a 22% recovery of systolic pressure, massive CPK release and a deterioration in mitochondrial function. Tissue contents of GSH and of protein SH were severely decreased, while those of GSSG were increased. The GSH/GSSG ratio was reduced from the aerobic value of 50 to 13.4, suggesting that an oxidative stress has occurred. N-acetylcysteine infused for 60 mins before ischaemia determined a 38% increase in tissue content of GSH with no major changes of GSSG or protein SH. The ischaemic-induced decrease of GSH and protein SH was also limited by pretreatment with N-acetylcysteine and there was no accumulation of GSSG after reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Assessment of myocardial perfusion with thallium-201 scintigraphy in exercise-induced left bundle branch block: diagnostic value and clinical significance.

Myocardial perfusion scintigraphy with thallium-201 was performed in 33 subjects (mean age 45 years, range 28-61) with exercise-induced, rate-dependent left bundle branch block (LBBB) in order to assess both the value of Thallium-201 myocardial imaging for the diagnosis of coronary artery disease (CAD) and the pathogenesis (ischaemic or not) of the conduction defect. Of the 33 patients evaluated, 16 had chest pain suggestive of CAD and 17 were asymptomatic. None had a history of prior myocardial infarction or clinical and echocardiographic signs of heart disease. LBBB appeared at a heart rate ranging from 70 to 160 b.min-1. Eighteen patients showed repolarization abnormalities (ST segment depression with deep inverted T waves) compatible with ischaemia, after QRS normalization. Thallium-201 myocardial uptake was normal in 12 subjects; in the remaining 21, reversible Thallium-201 defects were demonstrated in the septum (18 patients), septum and apex (2), and septum and infero-apical wall (1). No patient had irreversible defects and all had normal coronary angiography, with negative ergonovine tests for coronary artery spasm. The patients were followed up for a mean of 43 months (range 16-80). One patient died from sudden death, but no cardiac event occurred in the other patients. In conclusion, exercise Thallium-201 myocardial scintigraphy showed a high prevalence (64%) of reversible perfusion defects in a group of patients with exercise-induced LBBB without any evidence of CAD at angiography or coronary spasm at ergonovine test. Moreover, follow-up showed a relatively low rate of major cardiac events.     

Left ventricular dysfunction due to stunning and hibernation in patients

Left ventricular dysfunction is in most cases the consequence of myocardial ischemia. It may occur transiently during an attack of angina and usually it is reversible. It may persist over hours or even days in patients after an episode of ischemia followed by reperfusion, leading to the so-called condition of stunning. In patients with persistent limitation of coronary flow, left ventricular dysfunction may be present over months and years, or indefinitely in subjects with fibrosis, scar formation, and remodeling after myocardial infarction. Bowever, chronic left ventricular dysfunction does not mean permanent or irreversible cell damage. Bypoperfused myocytes can remain viable but akinetic. This type of dysfunction has been calledhibernating myocardium. The dysfunction due to hibernation can be partially or completely restored to normal by reperfusion. It is, therefore, important to clinically recognize a hibernating myocardium. In the present article we evaluate stunning and hibernation with respect to clinical decision making and, when possible, we refer to our ongoing clinical experience.     

Titanium dioxide nanotubes with triazine-methacrylate monomer to improve physicochemical and biological properties of adhesives

ObjectiveFormulate experimental adhesives containing titanium dioxide nanotubes (nt-TiO₂) or titanium dioxide nanotubes with a triazine-methacrylate monomer (nt-TiO₂:TAT) and evaluate the effect of these fillers on the physical, chemical, and biological properties of the adhesives.MethodsFirst, nt-TiO₂ were synthesized via a hydrothermal method. The nt-TiO₂ were mixed with a triazine-methacrylate monomer (TAT) to formulate nt-TiO₂:TAT, which were characterized by transmission electron microscopy (TEM). The nt-TiO₂, TAT, and nt-TiO₂:TAT were evaluated via Fourier Transform Infrared, Ultraviolet–visible, and micro-Raman spectroscopies. An experimental adhesive resin was formulated with bisphenol A glycerolate dimethacrylates, 2-hydroxyethyl methacrylate, and photoinitiator/co-initiator system. nt-TiO₂ or nt-TiO₂:TAT were incorporated at 2.5 wt.% and 5 wt.% in the adhesive. The base resin without nt-TiO₂ or nt-TiO₂:TAT was used as a control group. The adhesives were evaluated for antibacterial activity, cytotoxicity, polymerization kinetics, degree of conversion (DC), Knoop hardness, softening in solvent (ΔKHN%), ultimate tensile strength (UTS), 24 h- and 1 year- microtensile bond strength (μ-TBS).ResultsTEM confirmed the nanotubular morphology of TiO₂. FTIR, UV–vis, and micro-Raman analyses showed the characteristic peaks of each material, indicating the impregnation of TAT in the nt-TiO₂. Adhesives with nt-TiO₂:TAT showed antimicrobial activity against biofilm formation compared to control (p < 0.05), without differences in the viability of planktonic bacteria (p > 0.05). All groups showed high percentages of pulp cell viability. The polymerization kinetics varied among groups, but all presented DC above 50%. The addition of 5 wt.% of nt-TiO₂ and both groups containing nt-TiO₂:TAT showed higher values ??of Knoop hardness compared to the control (p < 0.05). The groups with nt-TiO₂:TAT presented lower ΔKHN% (p < 0.05) and higher UTS (p < 0.05) than the control group. After one year, the group with 5 wt.% of nt-TiO₂, as well as both groups containing nt-TiO₂:TAT, showed higher μ-TBS than the control (p < 0.05).SignificanceThe mixing of a triazine-methacrylate monomer with the nt-TiO₂ generated a filler that improved the physicochemical properties of the adhesive resins and provided antibacterial activity, which could assist in preventing carious lesions around tooth-resin interfaces. The set of physical, chemical, and biological properties of the formulated polymer, together with the greater stability of the bond strength over time, make nt-TiO₂:TAT a promising filler for dental adhesive resins.     

Left ventricular geometry correlates with early repolarization pattern in adolescent athletes

Some forms of early ECG repolarization QRS pattern (ERp) with J‐point elevation of 0.1 mV in two contiguous inferior and/or lateral leads with or without ST‐elevation are potentially associated with a higher arrhythmic risk in adults. We assessed the prevalence of ERp among non‐professional adolescent athletes and correlated it with age, sex, ethnicity, and structural and electric cardiac parameters. We retrospectively analyzed 414 ECGs obtained from young athletes referred to our center from 2006 to 2017. We found ERp in 22% of cases. In the ERp group, we found a greater percentage of black athletes, a higher systolic blood pressure, and lower heart rate (HR) compared with the group without ERp. This pattern was less frequent in female athletes. In athletes with ERp, the occurrence of ventricular ectopic beats was less frequent and QRS‐duration was shorter. They also exhibited greater (a) ECG‐based left ventricular hypertrophy (LVH), (b) left ventricular mass, and (c) relative wall thickness (RWT), suggesting a tendency to concentric geometry. At logistic regression analysis, we found that HR (OR 0.98 [0.96‐0.99] P = .013), QRS‐duration (OR 0.96 [0.94‐0.99], P = .003), LVH (OR 1.09 [1.05‐1.12], P < .001), and RWT (OR 1.08 [1.01‐1.16] P = .032) were significant predictors of ERp incidence. ERp is quite common in adolescent athletes and correlates with concentric LV remodeling. Specific clinical and ECG‐findings related to training such as lower HR, LVH, and QRS‐duration are also predictors of ERp. In adolescent non‐professional athletes, ERp is a benign finding associated with some structural and electric cardiac modifications induced by training.     

Myocardial "bridges". A new pathogenetic problem in angina without coronary obstruction (author's transl)]

Six patients showing at coronary angiography normal coronary arteries during dyastole, but a segmental constriction of the left anterior descending artery during systole, were studied. Four of these patients in which the degree of systolic artery narrowing was more evident had typical angina and positive stress test. In two of these cases, a probable idiopathic cardiac hypertrophy was present. The pathogenetic significance of the angiographic findings are discussed, on the basis of common knowledge of coronary physiology and of pathophysiology of angina with normal coronary arteries.