The haemodynamic performance of the Trifecta bioprosthesis was superior to that of the Magna Ease valve across all conventional prosthesis sizes, with almost no incidence of severe patient-prosthesis mismatch. The long-term follow-up is needed to determine whether these significant haemodynamic differences will persist, and influence clinical outcomes.
In animal experiments, elevating systolic pressures induces diastolic dysfunction and may contribute to congestion, a finding not yet translated to humans. Coronary surgery patients (63 ± 8 years) were studied with left ventricular (LV) pressure (n = 17) or pressure-volume (n = 3) catheters, immediately before cardiopulmonary bypass. Single-beat graded pressure elevations were induced by clamping the ascending aorta. Protocol was repeated after volume loading (n = 7). Consecutive patients with a wide range of systolic function were included. Peak isovolumetric LV pressure (LVP iso ) ranged from 113 to 261 mmHg. With preserved systolic function, LVP elevations neither delayed relaxation nor increased filling pressures. With decreasing systolic function, diastolic tolerance to afterload progressively disappeared: relaxation slowed and filling pressures increased (diastolic dysfunction). In severely depressed systolic function, filling pressures increased even with minor LVP elevations, suggesting baseline load-dependent elevation of diastolic pressures. The magnitude of filling pressure elevation induced in isovolumetric heartbeats was closely and inversely related to systolic performance, evaluated by LVP iso (r = -0.96), and directly related to changes in the time constant of relaxation s (r = 0.95). The maximum tolerated systolic LVP (without diastolic dysfunction) was similarly correlated with LVP iso (r = 0.99). Volume loading itself accelerated relaxation, but augmented afterloadinduced upward shift of filling pressures (7.9 ± 3.7 vs. 3.0 ± 1.5; P \ 0.01). The normal human response to even markedly increased systolic pressures is no slowing of relaxation and preservation of normal filling pressures. When cardiac function deteriorates, the LV becomes less tolerant, responding with slowed relaxation and increased filling pressures. This increase is exacerbated by volume loading.
New Findings r What is the central question of this study?The aim of the present study was to characterize the intraventricular pressure gradients (IVPGs) along the cardiac cycle, to correlate them with myocardial segmental asynchrony and to evaluate their response to regional myocardial ischaemia and ventricular afterload. r What is the main finding and its importance?We showed the existence of diastolic and systolic IVPGs in the left ventricle (LV) and demonstrated for the first time that normal gradient pattern is related to physiological asynchrony between basal and apical myocardial segments. Moreover, we showed that IVPG, a marker of normal left ventricular function, can be attenuated, lost entirely, or even reversed after regional acute ischaemia and afterload elevations.The aim of the present study was to characterize the intraventricular pressure gradients (IVPGs) througout the cardiac cycle, to correlate them with myocardial segmental asynchrony and to evaluate the effects of ischaemia and modulation by afterload. Open-chest anaesthetized rabbits (n = 6) were instrumented with pressure-tip micromanometers placed in the apex and outflow tract of the left ventricular (LV) cavity and with sonomicrometer crystals placed in the apex and base of the LV free wall to measure IVPGs and myocardial segment length changes during basal, afterloaded (aortic cross-clamping) and ischaemic conditions (left anterior descending coronary artery ligation). During early diastole (rapid filling), we recorded an IVPG (4.6 ± 0.7 mmHg) from the cardiac base towards the apex followed by an apex-to-outflow pressure gradient (3.6 ± 0.2 mmHg). During systole, we recorded an IVPG (0.6 ± 0.1 mmHg) from apex to outflow during early rapid ejection, which inverted during late slow ejection. Interestingly, the maximal rate of LV pressure fall occurred earlier and relaxation rate was faster in the base than in the apex. While shortening of basal segments was complete at the end of ejection, apical segments always showed a significant amount of postsystolic shortening. The IVPGs were entirely lost during ischaemia and attenuated by afterload elevations. During ischaemia, systolic shortening of the apical segment decreased, while postsystolic shortening increased. The present study confirms the existence of diastolic and systolic IVPGs in the LV and demonstrates, for the first time, that this normal gradient pattern is related to physiological asynchrony between basal and apical myocardial segments. Moreover, we show that the IVPG, a marker of normal left ventricular
The first Cox-maze procedure was performed in 1987, demonstrating the feasibility of a non-pharmacological treatment for atrial fibrillation (AF). Since then, surgery for AF has changed over time, in parallel with technological advances. Replacement of surgical incisions with linear ablation lines made a previously cumbersome procedure accessible to most surgeons, without compromising success. On the other hand, new ablation technologies paved the way for the development of minimally invasive surgery, which may potentially extend the scope of surgery to patients who would otherwise be deemed unsuitable. Nonetheless, literature on minimally invasive surgery is still scarce and randomized clinical trials currently under way are expected to shed light on some controversial issues. Moreover, successful AF treatment will probably rely on close collaboration between surgery and electrophysiology. Indeed, the hybrid procedure, though still in its very beginning, seems to combine the best of catheter and surgical ablation. However, further studies are warranted to determine the effectiveness of this promising strategy, especially in patients with persistent and longstanding persistent AF. Better understanding of AF pathophysiology as well as more accurate preoperative localization of AF triggers will bring about the possibility of tailoring specific lesion sets and ablation modalities to individual patients. This, in turn, will increase recovery and maintenance of sinus rhythm, with significant benefits in long-term outcomes.
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