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M Buchalter

Publications and source records attributed to M Buchalter.

7 recordsLinked to original sources
PubMed1994

Physiological pacing improves symptoms and increases exercise capacity in the elderly patient.

We evaluated the benefits of physiological pacing in the elderly by recruiting 13 subjects > 75 years of age, already fitted with a physiological pacing system. All had been paced for complete or Mobitz II heart block. Double blind cross over study was performed comparing exercise capacity, measuring distance walked on a 6-min walking test and time taken to climb two flights of stairs; and symptoms, evaluated by an activity of daily living questionnaire, in atrioventricular synchronous and ventricular pacing. Mean distance walked was significantly higher in atrioventricular synchronous than in ventricular pacing (360 +/- 65 m vs. 327 +/- 69 m; P < 0.01). No significant difference was found in the ability to climb stairs but there was a marked improvement in the symptomatic questionnaire score, 19 +/- 5 in physiological pacing increasing to 28 +/- 10 with ventricular. Physiological pacing in the elderly produces an increase in exercise tolerance and improves symptoms; therefore, age alone should not be a contraindication to a physiological system.

Activities of Daily Living↗
PubMed1992

A conical model to describe the nonuniformity of the left ventricular twisting motion.

The systolic contraction and fiber shortening in the left ventricle (LV) produces torsional moments in the myocardium, resulting in a gradient of angular displacements about the long axis. This is manifested as a counterclockwise rotation of the apex relative to the base, when viewed from the apex. Recent studies with magnetic resonance imaging (MRI), using noninvasive magnetic tags, have revealed three important properties of the LV twist: (a) The angle of twist (i.e., the angular rotation of a slice relative to the basal slice) is consistently higher at the endocardium as compared to the epicardium; (b) The twist increases towards the apex; and (c) Straight MRI-tagged radial lines at end-diastole (ED) are slightly curved at end-systole (ES), implying a nonlinear transmural variation of the twist. The present study suggests that the geometry of the LV at ES can be represented by a thick-walled hollow cone, and that the transmural twist patterns from ED to ES can be described using the continuum mechanics approach and a small strain analysis of an isotropic cone subjected to external torque. The predicted results are compared with the noninvasive MRI measurements of transmural twist in eight human volunteers. Given the epicardial angles of twist of each slice, the predicted endocardial angles of twist are in good correlation with the experimental findings (r = 0.86, slope = 1.09, SEE = 4.1 degrees). In addition, the model reliably describes the changes in the twist magnitude from apex to base (no significant difference from experimental values, P = 0.2), and predicts the curvilinear pattern at ES of the originally straight ED radial lines. Thus, the conical model with uniform properties of the LV, reliably predicts the nonuniformity of the twist patterns, implying that the LV twist is strongly affected by LV geometry.

Adult↗