Cardiopulmonary resuscitation with a novel chest compression device in a porcine model of cardiac arrest: improved hemodynamics and mechanisms.

OBJECTIVES: The goal of this study was to determine the magnitude and mechanisms of hemodynamic improvement of an automated, load-distributing band device (AutoPulse, Revivant Corp., Sunnyvale, California) compared with conventional cardiopulmonary resuscitation (C-CPR). BACKGROUND: Improved blood flow during cardiopulmonary resuscitation (CPR) enhances survival from cardiac arrest. METHODS: AutoPulse CPR (A-CPR) and C-CPR were performed on 30 pigs (16 +/- 4 kg) 1 min after induction of ventricular fibrillation. Aortic and right atrial pressures were measured with micromanometers. Regional flows were measured with microspheres; A-CPR and C-CPR were performed with 20% anterior-posterior chest compression, with (n = 10) and without (n = 10) epinephrine. A pressure transducer was advanced down the airways during chest compressions (n = 10), and magnetic resonance imaging (MRI) was performed. RESULTS: AutoPulse CPR improved coronary perfusion pressure (CPP) (aortic - right atrial pressure) without epinephrine (A-CPR 21 +/- 8 mm Hg vs. C-CPR 14 +/- 6 mm Hg, mean +/- SD, p < 0.0001) and with epinephrine (A-CPR 45 +/- 11 mm Hg vs. C-CPR 17 +/- 6 mm Hg, p < 0.0001). AutoPulse CPR improved myocardial flow without epinephrine and cerebral and myocardial flow with epinephrine (p < 0.05). AutoPulse CPR also produced greater myocardial flow at every CPP (p < 0.01). With A-CPR, high airway pressure was noted distal to the carina, which corresponded to an area of airway collapse on MRI, and which was not present with C-CPR. CONCLUSIONS: AutoPulse CPR improved hemodynamics over C-CPR in this pig model. AutoPulse CPR with epinephrine can produce pre-arrest levels of myocardial and cerebral flow. The improved hemodynamics with A-CPR appear to be mediated through airway collapse, which likely impedes airflow and helps maintain higher levels of intrathoracic pressure.

Pulmonary vein anatomy in patients undergoing catheter ablation of atrial fibrillation: lessons learned by use of magnetic resonance imaging.

BACKGROUND: This study sought to define the technique and results of magnetic resonance imaging (MRI) of pulmonary vein (PV) anatomy before and after catheter ablation of atrial fibrillation (AF). METHODS AND RESULTS: Twenty-eight patients with AF underwent ablation. Patients underwent gadolinium-enhanced MRI before and 6 weeks after their procedures. A control group of 27 patients also underwent MRI. Variant PV anatomy was observed in 38% of patients. AF patients had larger PV diameters than control subjects, but no difference was observed in the size of the PV ostia among AF patients. The PV ostia were oblong in shape with an anteroposterior dimension less than the superoinferior dimension. The left PVs had a longer "neck" than the right PVs. A detectable PV narrowing was observed in 24% of veins. The severity of stenosis was severe in 1 vein (1.4%), moderate in 1 vein (1.4%), and mild in 15 veins (21.1%). All patients were asymptomatic, and none required treatment. CONCLUSIONS: This study demonstrates that AF patient have larger PVs than control subjects and demonstrates the value of MRI in facilitating AF ablation. The benefits of preprocedural MRI of PVs include the ability to evaluate the number, size, and shape of the PVs. MRI also provides an assessment of the severity of PV stenosis.

Public access defibrillation in the Caribbean: the time has come

Recent technological advances in resuscitation equipment and procedures have opened the door for some developing countries to consider implementing early defibrillation programmes. This is particularly true in the Caribbean, where urbanisation is rapidly altering the nature of health problems, and public expectations of healthcare delivery is rapidly rising. However before an SCD victim in the Caribbean can expect to be rescued from a cardiac arrest there is much work to be done. 'Core ACLS' courses that emphasise the critical aspects of ACLS, coupled with widespread teaching programmes aimed at educating the general public about cardiovascular resuscitation, should be initiated. Before full advantage can be taken of recent technological advances, and emergency medical systems can become a reality in the Caribbean, a comprehensive approach to the introduction of resuscitative practices should be considered (AU)