How His bundle pacing prevents and reverses heart failure induced by right ventricular pacing.

Ideal heart performance demands vigorous systolic contractions and rapid diastolic relaxation. These sequential events are precisely timed and interdependent and require the rapid synchronous electrical stimulation provided by the His-Purkinje system. Right ventricular (RV) pacing creates slow asynchronous electrical stimulation that disrupts the timing of the cardiac cycle and results in left ventricular (LV) mechanical asynchrony.

What Is the Heart? Anatomy, Function, Pathophysiology, and Misconceptions.

Cardiac dynamics are traditionally linked to a left ventricle, right ventricle, and septum morphology, a topography that differs from the heart's five-century-old anatomic description of containing a helix and circumferential wrap architectural configuration. Torrent Guasp's helical ventricular myocardial band (HVMB) defines this anatomy and its structure, and explains why the heart's six dynamic actions of narrowing, shortening, lengthening, widening, twisting, and uncoiling happen. The described structural findings will raise questions about deductions guiding "accepted cardiac mechanics", and their functional aspects will challenge and overturn them.

Effects of antegrade versus integrated blood cardioplegia on left ventricular function evaluated by echocardiographic real-time 3-dimensional speckle tracking.

Objective: The objective of this study was to evaluate left ventricular free wall and interventricular septal function by 2-dimensional transthoracic echocardiography and live/real-time 3-dimensional transthoracic speckle tracking echocardiography before and after on-pump cardiac surgery and to assess the effect of mode of cardioplegia delivery.

Methods: A total of 22 patients were studied 1 day before and 4 to 5 days after surgery. Cold blood cardioplegia was delivered by intermittent antegrade infusion or by the integrated method.

Ventricular structure-function relations in health and disease: Part I. The normal heart.

The heart's structure-function relationships explain normal cardiac dynamics and clarify how they are disrupted by disease. For 500 years, anatomists described circumferential and helical cardiac fibres, yet disagreed about their relationships. One current model is attributed to Torrent Guasp who described functional pathways, the helical ventricular myocardial band (HVMB) with two interconnected loops: an outer basal loop with transverse fibres surrounds an inner apical helical loop that is composed of oblique descending and ascending segments that create a conical apical vortex.

Ventricular structure-function relations in health and disease: part II. Clinical considerations.

Normal cardiac function of the left and right ventricles, together with the septum, is related to form/function interactions within the helical ventricular myocardial band. This knowledge is a prerequisite to understanding form/function interactions in diseases and for planning new treatments. Topics discussed include congestive heart failure in dilated hearts of ischaemic, valvar or nonischaemic origin as well as diastolic dysfunction.

Right ventricular architecture responsible for mechanical performance: unifying role of ventricular septum.

The right ventricle (RV) is composed of a free wall containing a wrap-around circumferential muscle at its base and a septum composed of helical fibers that are oblique and cross each other at 60° angles. This structure is defined by the helical ventricular myocardial band and defines RV function because the wrap-around transverse fibers constrict or compress to cause the bellows motion responsible for 20% of RV output, whereas the oblique fibers determine shortening and lengthening that produces 80% of RV systolic function. Clinical shortening is quantified by tricuspid annular plane systolic excursion and measured by echocardiography.

Surgical ventricular restoration: where do we go from here?

The surgical treatment for ischemic heart failure (STICH) trial concluded that the addition of surgical ventricular restoration (SVR) to coronary bypass grafting did not lead to improved survival in patients with dilated ischemic cardiomyopathy. Observational studies at multiple centers over the last 15 years have shown consistent improvement in global ventricular function and approximately 70 % long-term survival. The causes of this discrepancy are reviewed here and likely relate to how the STICH trial was conducted.

Two- and three-dimensional speckle tracking echocardiography: clinical applications and future directions.

Two-dimensional speckle tracking echocardiography (2D STE) is a novel technique of cardiac imaging for quantifying complex cardiac motion based on frame-to-frame tracking of ultrasonic speckles in gray scale 2D images. Two-dimensional STE is a relatively angle independent technology that can measure global and regional strain, strain rate, displacement, and velocity in longitudinal, radial, and circumferential directions. It can also quantify rotational movements such as rotation, twist, and torsion of the myocardium.