Anesthetic management of the patient with low ejection fraction.

The number of patients with heart failure presenting for surgery continues to rise, and anesthesiologists are increasingly being called upon to provide quality, safe care in the operating room for patients with low ejection fraction (EF). Perioperative goals in the management of these patients include maintaining forward flow, promoting inotropy without inducing or exacerbating ischemia, and returning patients to their preoperative level of function after surgery. Oftentimes, these goals can be met with pharmacologic support, including the use of calcium channel blockers, phosphodiesterase inhibitors, and novel agents, such as nesiritide and levosimendan. Many patients with diminished EF have implantable cardioverter-defibrillators (ICDs) in place. These devices can be complex to manage, and concern often arises regarding electromagnetic interference from monopolar cautery. Although simply placing a magnet on the device will often disable the antitachycardia interventions of an ICD, this is not always the case. The safest way to manage an ICD in the perioperative period is to interrogate and reprogram the device before and after surgery. Another helpful device in dealing with patients with low EF, particularly those in acute cardiogenic shock, is the intra-aortic balloon pump. These devices can serve a critical role in managing patients who have inadequate responses to pharmacologic therapy or in whom vasopressor and inotropic support are suboptimal because of concerns for increasing myocardial work. With full understanding of available pharmacologic agents, and an appreciation of the capabilities of ICDs and intra-aortic balloon pumps, anesthesiologists will be better equipped to meet the perioperative needs of the patient with low EF.

Acute Effects of Pacing at Different Ventricular Sites on Left Ventricular Rotational Mechanics in a Porcine Model.

OBJECTIVE: The purpose of this study was to examine the acute effects of pacing at different ventricular sites on hemodynamics and left ventricular (LV) rotational mechanics using speckle-tracking echocardiography (STE) in a porcine model. DESIGN: A prospective laboratory investigation. SETTING: University research laboratory. PARTICIPANTS: Yorkshire pigs. INTERVENTIONS: In 9 pigs, after midline sternotomy, epicardial pacing was performed from the right ventricular outflow tract (RVOT), right ventricular apex (RVA), and LV free wall. MEASUREMENTS AND MAIN RESULTS: Two-dimensional STE and conductance catheter-derived LV pressure-volume measurements were made to determine the impact of pacing from various sites on LV rotational parameters (twist/untwist) and hemodynamics. RVOT pacing caused the least decrease in end-systolic pressure from baseline (-9.5%), when compared with RVA (-19.1%) and LV (-23.4%). Systolic and diastolic parameters (Emax, Tau) also were different among RVOT (4.7±0.8 mmHg/mL, 32±4 ms), RVA (3.9±0.7 mmHg/mL, 37±6 ms), and LV sites (3.6±0.8 mmHg/mL, 42±7 ms). Similar to the effects of pacing on hemodynamics, RVOT pacing better preserved LV twist (11.1±1.8 v 8.6±1.7, 5.9±0.7 °) and untwisting rate (64.6±8.5 v 56.2±5.3, 48.2±8.5 °/s) when compared with RV apical pacing and LV pacing. Furthermore, prolongation of conduction from LV lateral to anteroseptal at LV base (26.5±3.8 v 13.8±3.3 ms, p<0.05) and LV midpapillary muscle level (35.6±5.6 v 14.1±2.4 ms, p<0.05) was observed with LV pacing compared with RVOT pacing. CONCLUSIONS: The present data showed that the LV twist/untwist and cardiac systolic and diastolic function were least affected by RVOT pacing. This finding may be explained by the proximity of this location to the native ventricular conduction system.