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Abstract: Hypertension (HT) is associated with left ventricular (LV) diastolic dysfunction and consequent left atrial (LA) dilatation. We investigated changes in LA size and phasic function by decade in patients with HT. Patients with mild or moderate HT (n = 122) were compared with a case controlled normal cohort (blood pressure <140/90 mm Hg). Biplane LA maximum, minimum, and pre ‘a’ wave volumes were measured; LA filling, passive emptying, and active emptying volumes and fractions were calculated. Transmitral inflow and pulsed wave mitral annular tissue Doppler velocity were measured as expressions of LV diastolic function. The HT group had larger LA maximum volumes compared with normal controls for all decades until the 8th decade. Subjects with HT in decade 4 had LA maximum volume similar to that of normal controls from decade 8 (27.8 ± 4.3 mL/m2 vs 25.6 ± 6.1 mL/m2 respectively, P = .22). Active emptying volume and fraction were higher in the HT group across all decades, while there was no difference between the HT and normal groups for passive emptying volume. LV mass and E/E′ ratio were significantly higher across all decades in the HT group. HT alters atrial dynamics significantly, with resultant increased LA volume and active emptying volume consequent to altered LV diastolic function. HT ‘accelerates’ the normal aging process with patients as early as decade 4 having similar LA size to that of normal controls in decade 8. This premature increase in LA volume may result in the future development of atrial fibrillation in HT patients. [Copyright &y& Elsevier]

Objectives: This study investigated changes in left atrial (LA) volumes and phasic atrial function, by deciles, with normal aging. Background: LA volume increase is a sensitive independent marker for cardiovascular disease and adverse outcomes. To use this variable more effectively as a marker of pathology and a gauge of outcome, physiological changes due to aging alone need to be quantitated. Methods: A detailed transthoracic echocardiogram was performed in 220 normal subjects; 89 (41%) were male and their age ranged from 20 to 80 years (mean 45 ± 17 years). Maximum (end-ventricular systole), minimum (end-ventricular diastole), and pre–a-wave volumes were measured using the biplane method of disks. LA filling, passive emptying, conduit and active emptying volumes, and fractions were calculated. Transmitral inflow, pulmonary vein flow, and pulsed-wave Doppler tissue imaging parameters were measured as expressions of left ventricular diastolic function. For purposes of analysis, subjects were divided by age deciles. Results: LA indexed maximum (0.05 ml/m2 per year) and minimum (0.06 ml/m2 per year) volume increased with age but only became significant in the eighth decade (26.0 ± 6.3 ml/m2, p = 0.02, and 13.5 ± 3.9 ml/m2, respectively; p < 0.001). Impaired left ventricular diastolic relaxation was apparent in decade 6 and was associated with a shift in phasic LA volumes so that LA expansion index and passive emptying decreased with increasing age, whereas active emptying volume increased. Conclusions: In normal healthy subjects, LA indexed volumes remain nearly stable until the eighth decade when they increase significantly. Therefore, an increase in LA size that occurs before the eighth decade is likely to represent a pathological change. Changes in phasic atrial volumes develop earlier consequent to age-related alteration in LV diastolic relaxation. [ABSTRACT FROM AUTHOR]

The aim of this study was to quantitate regional atrial contractility in patients with atrial fibrillation (AF) maintained in sinus rhythm after creating lines of block by intraoperative linear radiofrequency ablation for AF. We hypothesized that left atrial regional and global function remains impaired after radiofrequency ablation, despite restoration of sinus rhythm in this cohort. Patients with chronic AF maintained in sinus rhythm ≥6 months after radiofrequency ablation (n = 28) were studied and compared with a chronic AF group who, after standard electrical transthoracic cardioversion, were maintained in sinus rhythm for 6 months (n = 32) and a normal cohort (n = 32). Using color Doppler tissue imaging (CDTI), segmental atrial contraction was measured from annular, mid, and superior locations of the left atrium in both the apical 4- and 2-chamber views and of the right atrium in the apical 4-chamber view. Peak positive strain (SI) and atrial strain rate in early (E-sr) and late diastole (A-sr) were measured from mid and superior segments in both the apical 4- and 2-chamber views of the left atrium. The radiofrequency ablation group had significantly lower CDTI, SI, and A-sr values in all segments compared with both the cardioversion and normal groups. The cardioversion group had lower CDTI velocities than normal subjects. In the radiofrequency ablation group, CDTI velocities, SI, and A-sr values of the inferior and lateral segments were differentially and substantially lower than noted in other segments. In conclusion, patients with chronic AF have significant persistent left atrial dysfunction, despite restoration and maintenance of sinus rhythm. Additive global and regional atrial dysfunction was present in the radiofrequency ablation group suggestive of injury caused by the ablation process. These findings may have implications for selecting the duration of subacute and chronic anticoagulation after anatomic alteration of left atrial endocardium using radiofrequency ablation as a means of restoring sinus rhythm in chronic AF. [Copyright &y& Elsevier]

: BackgroundThe optimal technique for producing linear radiofrequency thermal lesions in myocardial tissue is unclear. We compared epicardial ablation on the beating heart with endocardial ablation after cardioplegia.: MethodsRadiofrequency lesions were produced using a multielectrode malleable handheld probe in ovine myocardium with three wall thicknesses. Detailed analysis of lesion dimensions was used to assess the effects of site of ablation, muscle thickness, and duration of ablation.: ResultsAfter epicardial atrial ablation, myocardial lesions were detected in all sections without macroscopically visible epicardial fat (n = 10), but only 43% (6/14) of sections with epicardial fat. Three of 24 atrial epicardial sections (13%) and 92% (23/25) of endocardial atrial lesion sections were clearly transmural. In thicker tissues lesion depth was independent of endocardial (right ventricle: 3.9 ± 1.1 mm, left ventricle: 3.8 ± 0.7 mm) or epicardial (right ventricle: 3.4 ± 0.6 mm, left ventricle: 4.3 ± 0.9 mm) ablation site. Epicardial lesions are less deep in thinner areas of myocardium (p = 0.003). Lesions were all wider than they were deep. There was no significant increase in lesion depth with the increase in ablation duration from 1 to 2 minutes.: ConclusionsLesions were unlikely to be transmural with either technique when the wall thickness was greater than about 4 mm. Epicardial fat has an important negative effect on epicardial lesion formation. Where epicardial fat is absent epicardially produced lesions penetrate less deeply when the wall thickness is small, possibly due to endocardial cooling by circulating blood. Prolongation of the duration of ablation from 1 to 2 minutes does not significantly increase lesion depth. [Copyright &y& Elsevier]