Patient Selection for Biventricular Pacing

Biventricular Pacing. Introduction: Biventricular pacing improves functional status in the majority of patients with drug‐refractory heart failure, dilated cardiomyopathy, and interventricular conduction delay. The aim of this study was to analyze the baseline clinical and functional data of a cohort of patients implanted with a biventricular stimulation system in a single‐center experience, to verify if the pathophysiologic characteristics of patients affect outcome, and to determine if preliminary identification of the right candidates for the new therapy is possible with noninvasive parameters. Methods and Results: Since March 1999, 52 patients with advanced heart failure (idiopathic cardiomyopathy 50%, ischemic cardiomyopathy 35%, other etiology 15%) and left bundle branch block underwent cardiac resynchronization and were followed prospectively. Paired analysis over mean (± SD) follow‐up of 348 ± 154 days showed an overall significant decrease of QRS width (baseline 194 ± 33.2 msec vs follow‐up 159.6 ± 20.1 msec), New York Heart Association (NYHA) functional class (baseline 3.2 ± 0.5 vs follow‐up 2.3 ± 0.5), quality‐of‐life score (baseline 54 ± 25 vs follow‐up 25 ± 16), and increase of maximal VO₂ (baseline 12.6 ± 2.5 mL/kg/min vs follow‐up 15.0 ± 3.3 mL/kg/min). There were 80% responders (documented, persistent decrease ≥1 NYHA class) and 20% nonresponders (same NYHA class or decline of status; need for heart transplant; death due to progressive pump failure). No significant differences in baseline clinical and functional variables between the two subgroups were observed. In responders, there was a highly significant global improvement of all variables; in nonresponders, no parameters changed between baseline and follow‐up. Conclusion: These data confirm the role of biventricular pacing in improving the functional status of the great majority of a selected patient population having advanced heart failure and left bundle branch block with wide QRS complex. Basal demographic, clinical, and functional characteristics are not helpful in preliminary selection of responders. Simple evaluation of NYHA class confirms favorable outcome (improvement of functional and hemodynamic status).     

Relevance of Echocardiographic Evaluation of Right Ventricular Function in Patients Undergoing Cardiac Resynchronization Therapy

Aims: Right ventricular (RV) dysfunction is a marker of poor prognosis in heart failure (HF) patients. It is still unclear whether RV function might influence response to cardiac resynchronization therapy (CRT).
Methods: Forty-four consecutive patients with HF, large QRS, and either intraventricular or interventricular dyssynchrony underwent echocardiographic evaluation before, 1 month after, and 6 months after CRT. Response to CRT was considered in case of significant LV reverse remodeling, defined as the occurrence of LV end-systolic volume (LVESV) reduction ≥15% at 6 months.
Results: All echocardiographic indexes of baseline RV function and dimensions were significantly more impaired in nonresponders versus responders to CRT: tricuspid annular plane systolic excursion (TAPSE 15 ± 4 mm vs 20 ± 5 mm, P = 0.001), RV systolic pulmonary artery pressure (RVSP 39 ± 14 mmHg vs 27 ± 8 mmHg, P = 0.02), RV end-diastolic area (RVEDA 23 ± 6 cm² vs 16 ± 3 cm² P < 0.001), RV end-systolic area (RVESA 16 ± 6 cm² vs 8 ± 2 cm², P = 0.001), and RV fractional area change (30 ± 12% vs 48 ± 8%, P < 0.001). All the indexes of RV function significantly correlated with the percentage of LVESV reduction after CRT. Severe RV dysfunction was defined as TAPSE ≤14 mm and the population was stratified into two groups based on baseline TAPSE ≤ or > 14 mm. As compared to those with high TAPSE (n = 30), patients with low TAPSE (n = 14) were less likely to show LV reverse remodeling after CRT (76% vs 14%, P < 0.001).
Conclusions: Our study suggests that RV function significantly affects response to CRT. Poor LV reverse remodeling occurs after CRT in patients with HF having severe RV dysfunction at baseline.     

Respiratory patterns during sleep in Down's syndrome: importance of central apnoeas

Obstructive sleep apnoea episodes have been reported repeatedly in Down's syndrome (DS) patients as a consequence of the presence of predisposing malformations or intercurrent pathology of the upper airways. There are no data on respiratory patterns of uncomplicated Down's syndrome subjects. In order to evaluate the eventual effects of central nervous system (CNS) impairment on respiration in DS, we studied the respiratory patterns during sleep of a group of 10 DS subjects, aged 8.6–32.2 y, without relevant upper airway pathology. In order to control the possible effects of sleep structure and mental retardation on the results obtained, we compared the findings in DS with those obtained from a group formed by subjects affected by fragile X syndrome (six males and one female, aged 10.0–15.42 y), another genetically determined type of mental retardation. Sleep structure was similar in both groups; however, DS subjects showed significantly higher indices of central sleep apnoea and of oxygen desaturation than fragile X patients (P<0.005). As far as DS individuals were considered, a significant preponderance of central, as opposed to obstructive, sleep apnoeas was found (89.4% vs. 9.4%, respectively; 1.2% were mixed) which showed a significant age-related increase. Central respiratory pauses were mostly preceded by sighs, which occurred more frequently during sleep stages 1 and REM, and were often organized in long sequences of periodic-like breathing. During REM sleep, they were less frequently preceded by sighs and by body movements than during NREM sleep. Obstructive sleep apnoeas occurred more often during REM sleep and were more rarely preceded by sighs or by body movements. Both central and obstructive apnoeas induced significant oxygen desaturation in 50–69.6%. Sleep structure was not significantly modified by apnoeas and oxygen desaturation. We hypothesize that the increase in central sleep apnoeas is related to a dysfunction of the central respiratory control at a brainstem level in DS.     

Biventricular Pacing via a Persistent Left Superior Vena Cava: Report of Four Cases

GASPARINI, M., et al .: Biventricular Pacing via a Persistent Left Superior Vena Cava: Report of Four Cases. Persistence of left superior vena cava (LSVC) is an uncommon finding during pacemaker implantation, which may be particularly relevant in performing LV transvenous pacing. Rarely, it is further complicated by the presence of atresia of the coronary sinus ostium (CSO). This article reports the authors experience with biventricular pacing (Biv-P) in this unusual clinical setting. From October 1999 to April 2002, 158 patients underwent biventricular pacing. In four of them (mean age 62.2 years), the presence of a persistent LSVC draining into the coronary sinus (CS) was detected at implantation, associated with atresia of the CSO in two patients. A common characteristic was the angiographic finding of a large CS with few tributaries. The LV leads were successfully positioned in the middle cardiac vein in three patients and in a posterolateral vein in one patient. All vessels were large and their cannulation via downstream CS catheterization required the lead to be manipulated through sharp angles. Mean fluoroscopic exposure and procedural times were not significantly different from the overall Biv-P population. In all patients, at a mean follow-up of 11 months, sensing and capture threshold remained stable and a significant decrease in NYHA functional class and increase in LVEF were noted. The direct lead placement in large CS tributaries in the presence of persistent LSVC was feasible and safe. The leads remained stable up to a mean follow-up of nearly 1 year. (PACE 2003; 26[Pt. II]:192–196)     

Affinity purification of a difficult-sequence protein

A biotinylated derivative of a designed, difficult-sequence protein (the Minibody, Bianchi, E., Tramontano, A., Sollazzo, M. & Pessi, A. (1993) Int. J. Peptide Protein Res. 41 , 385–393) which represented only 3.7% of the crude, cleaved material was quantitatively recovered with about 70% purity, in a single step, by affinity chromatography on immobilised avidin. Purification to homogeneity was then easily achieved by preparative HPLC. This highly effective purification scheme must be contrasted with the previously shown multidimen- sional, low-yield chromatographic protocol. Since no facilitation of the purification had been obtained by capping alone, this result suggests that capping is useful only in conjunction with affinity chromatography.