Ventricular fibrillation induced by coagulating mode bipolar electrocautery during pacemaker implantation in Myotonic Dystrophy type 1 patient

The occurrence of ventricular fibrillation, induced by bipolar electrocautery during elective dual chamber pacemaker implantation, is reported in a patient affected by Myotonic Distrophy type 1 with normal left ventricular ejection fractionKey words: ventricular fibrillation, bipolar electrocautery, pacemaker implantation, Myotonic Dystrophy type 1     

The effect of atrial preference pacing on atrial fibrillation electrophysiological substrate in Myotonic Dystrophy type 1 population

P-wave dispersion is a non invasive indicator of intra-atrial conduction heterogeneity producing substrate for reentry, which is a pathophysiological mechanism of atrial fibrillation. The relationship between P-wave dispersion (PD) and atrial fibrillation (AF) in Myotonic dystrophy type 1 (DM1) patients is still unclear. Atrial Preference Pacing (APP) is an efficient algorithm to prevent paroxysmal AF in patients implanted with dual-chamber pacemaker. Aim of our study was to evaluate the possible correlation between atrial preference pacing algorithm, P-wave dispersion and AF burden in DM1 patients with normal cardiac function underwent permanent dual-chamber pacemaker implantation.We enrolled 50 patients with DM1 (age 50.3 ± 7.3; 11 F) underwent dual-chamber pacemaker implantation for various degree of atrioventricula block. The study population was randomized following 1 months stabilization period to APP algorithm features programmed OFF or ON. Patients were assessed every 3 months for the first year, and every 6 months thereafter up to 3 years. At each follow-up visit, we counted: the number of premature atrial beats, the number and the mean duration of AF episodes, AF burden and the percentage of atrial and ventricular pacing.APP ON Group showed lower number of AF episodes (117 ± 25 vs. 143 ± 37; p = 0.03) and AF burden (3059 ± 275 vs. 9010 ± 630 min; p < 0.04) than APP OFF Group. Atrial premature beats count (44903 ± 30689 vs. 13720 ± 7717 beats; p = 0.005) and Pwave dispersion values (42,1 ± 11 ms vs. 29,1 ± 4,2 ms, p = 0,003) were decreased in APP ON Group. We found a significant positive correlation between PD and AF burden (R = 0,8, p = 0.007).Atrial preference pacing algorithm, decreasing the number of atrial premature beats and the P-wave dispersion, reduces the onset and perpetuator factors of AF episodes and decreases the AF burden in DM1 patients underwent dual chamber pacemaker implantation for various degree of atrioventricular blocks and documented atrial fibrillation.Key words: atrial fibrillation, Myotonic Dystrophy, atrial preference pacing     

Non-furosemide-related renal calcifications in premature infants with bronchopulmonary dysplasia

Renal calcification is a known complication of long-term furosemide therapy in infants with bronchopulmonary dysplasia (BPD). In a prospective study the clinical course and long-term renal sequelae of renal calcifications of 19 consecutive premature neonates (birthweight < 1250 g) with bronchopulmonary dysplasia who did not receive furosemide were examined. Infants were divided into two different groups on the basis of ultrasound evidence of renal calcifications (RC group) or absence of renal calcifications (NRC group). Serial examinations, performed at the age of 1, 2, 3, 6, 9 and 12 months, showed that 12 infants at the mean age of 68.5 ± 12.8 days of life had renal calcifications (63%), and 3 of them had nephrolithiasis; 8 had bilateral renal calcifications. Among the 9 survivors, 2 had chronic renal calcifications at the age of 9 months; however, all normalized at the age of 12 months. Twelve infants received hydrochlorothiazide and spironolactone (63%), 17 had prolonged courses of xanthines and dexamethasone (89.5%), while furosemide was not part of the routine pharmacological administration. Statistical analysis showed that birthweight, gestational age, Apgar score and length of parenteral nutrition were comparable in the RC and NRC group infants. Mean serum creatinine, creatinine clearance, fractional sodium excretion and urinary calcium excretion values during the 12-month study period were comparable in the RC and NRC groups. Mechanical ventilation and hospital stay length were instead associated with renal calcification occurrence. The strongest indicator of renal calcification risk for this high-risk population is the severity of the unresolved acute lung disease, where different facets of respiratory management, other than the addition of furosemide, represent sufficient stimuli and renal injury to potentiate stone formation.     

The Pathology of Hancock Standard Porcine Valve Prosthesis: A 20-Year Span of Experience

A spectrum of events leading to tissue failure is responsible for late dysfunction of Hancock porcine valve xenografts: (a) Primary failure: dystrophic calcification, thrombosis, fibrous tissue overgrowth, primary tears, cuspal hematomas, and stent postbending. (b) Secondary failure: endocarditis and paravalvular leak. Dystrophic calcification is the main factor influencing long-term durability and accounts in our experience for 88% of primary failure, through different clinical presentations; particularly, incompetence by cusp tearing and egg-shell fragmentation is by far the most frequent mode of failure. Cusp degeneration by primary tears (in the absence of dystrophic calcification) is an uncommon event, due to lipid infiltration or to right coronary muscle shelf spontaneous or immuno-related disruption.     

Anomalies of the Systemic Venous Return: A Review

Congenital anomalies of the systemic venous connection to the heart represent a rather wide and heterogeneous group of malformations, whose physiological consequences may vary from nil to the most severe form of systemic arterial desaturation. The malformations may be summarized as follows: (1) Left superior vena cava connected to the coronary sinus, interrupted inferior vena cava and absent right superior vena cava that do not indicate surgical repair 'per se', but require some technical attention during open heart surgery performed for other anomalies; (2) Left superior vena cava connected to the left atrium, due to incorporation of the coronary sinus into the left atrial cavity, resulting in a right-to-left-shunt; (3) Right superior vena cava or inferior vena cava draining into the left atrium, both are extremely rare and require treatment for the ensuing right-to-left shunt; (4) Total anomalous systemic venous connection to the left atrium, usually combined with atrial isomerism and other very complex heart malformations; (5) Cor triatriatum dexter, which has been frequently diagnosed as an anomalous venous connection for its similar hemodynamic consequences. Such anomalies are reviewed with particular respect to their surgical implications.     

DDI Pacing in the Bradycardia-Tachycardia Syndrome

The bradycardia-tachycardia syndrome is a subgroup within the larger category of sinus node dysfunction. Pacing is often required to treat either the protracted asystolic spells following the spontaneous termination of a paroxysmal supraventricular tachyarrhythmia or to protect the patient from pharmacologically exacerbated bradycardias. While the optimal pacing mode for this subset of patients remains debatable, recent reports have favored the use of atrial ventricular sequential pacing with intact atrial sensing (DDI). This paper reports our experience with a series of 30 consecutive patients in whom the DDI mode was utilized as part of the management of this syndrome. DDI pacing has been demonstrated to be safe, extremely effective, and easy to use in this group of patients.     

Protected 1–3 segment of the peptaibol antibiotics alamethicin and hypelcin.

A study of the modes of folding and self-association of Z-Aib-l -Pro-Aib-OMe (the protected 1–3 segment of the peptaibol antibiotics alamethicin and hypelcin) in the solid state was performed using i.r. absorption and X-ray diffraction. The stereochemically constrained tripeptide molecules adopt a 4 ± 1 intramolecularly H-bonded form (β-turn), where the single intramolecular H-bond is found between the peptide N-H group of the Aib³ residue and the urethane C = O group of the N-blocking benzyloxycarbonyl moiety. This folded structure is stabilized by an intermolecular H-bond between the urethane N-H group of the Aib¹ residue and the peptide C = O group of the Pro² residue of a symmetry related molecule. According to the i.r. absorption data, in CH₂Cl₂ and TMP solutions the same intramolecularly H-bonded form occurs as that found in solid state. Compared to the situation in the solid state, in CH₂Cl₂ and TMP solvation of the urethane N-H group replaces self-association (through the same N-H group). The results are also discussed in relation to those obtained for other protected -Aib-X-Aib-(X = Aib, l -Ala, l -Val) tripeptide segments of peptaibol antibiotics.