Pharmacological vs Exercise Stress Echocardiography for Detection of Cardiac Allograft Vasculopathy.

OBJECTIVE: To test the hypothesis that exercise and dobutamine would provide levels of cardiac stress that are comparable to those achieved in a general stress test population, and to one another, in heart transplant recipients. PATIENTS AND METHODS: From February 10, 2015, to December 31, 2017, 81 patients underwent exercise stress (N=45) or dobutamine stress (N=36) echocardiography at a mean ± SD of 11±14 years (range, 1-29 years) after heart transplant. Hemodynamic and inotropic responses were compared between groups, and to a prior test, longitudinally. The primary outcome was peak heart rate (HR) × systolic blood pressure (SBP). RESULTS: Peak exercise HR × SBP × 10-3 was a mean ± SD of 24.9±4.9 mm Hg/min for exercise stress vs 21.2±3.4 mm Hg/min during dobutamine stress (P<.001). In 35 patients who underwent a dobutamine stress test followed later by another dobutamine stress test, peak HR × SBP changed by 4.2%±16% (P=.05). In 25 patients who underwent a dobutamine stress test followed later by an exercise stress test, peak HR × SBP increased by 12%±23% (P=.002 vs serial dobutamine stress tests). Peak exercise HR did not correlate with time since heart transplant, patient age, or graft age. Peak dobutamine HR correlated modestly with patient age (r 2 =0.28). Inotropic responses were similar in both groups. Overall, patients preferred exercise stress testing to dobutamine stress tests. Dobutamine stress testing was more expensive than exercise stress tests. CONCLUSION: Exercise induces a level of cardiac stress that is equal to or greater than dobutamine-induced stress, at lower cost, in heart transplant recipients who express preference for exercise stress testing.

Cardiopulmonary Resuscitation in Adults and Children With Mechanical Circulatory Support: A Scientific Statement From the American Heart Association.

Cardiac arrest in patients on mechanical support is a new phenomenon brought about by the increased use of this therapy in patients with end-stage heart failure. This American Heart Association scientific statement highlights the recognition and treatment of cardiovascular collapse or cardiopulmonary arrest in an adult or pediatric patient who has a ventricular assist device or total artificial heart. Specific, expert consensus recommendations are provided for the role of external chest compressions in such patients.

Liquid Ventilation for the Induction of Ultrafast Hypothermia in Resuscitation Sciences: A Review.

Liquid ventilation was initially proposed for lung lavage and respiratory support. More recently, it was also investigated as an experimental strategy for ultrafast cooling or organ preservation during ischemic disorders. The goal of this article is to identify and review the studies that investigated liquid ventilation in the field of resuscitation sciences. An exhaustive analysis of the literature was performed using the Medline database up to 15th September 2015. Articles were selected according to their relevance. All articles focusing on respiratory support were excluded. On the basis of 76 retrieved studies from the Medline database, 29 were included in this review. All studies were experimental reports and most of them investigated the cooling properties of liquid ventilation in animal models of experimental cardiac arrest or coronary artery occlusion in rabbits or pigs. Animal studies demonstrated a wide range of potential applications of total liquid ventilation in resuscitation sciences. This strategy is able to provide ultrafast cooling, independent of the body weight. In animal models of cardiopulmonary resuscitation, it was shown to provide potent benefits widely linked to cooling rapidity.

Total liquid ventilation offers ultra-fast and whole-body cooling in large animals in physiological conditions and during cardiac arrest.

INTRODUCTION: Total liquid ventilation (TLV) can cool down the entire body within 10-15 min in small animals. Our goal was to determine whether it could also induce ultra-fast and whole-body cooling in large animals using a specifically dedicated liquid ventilator. Cooling efficiency was evaluated under physiological conditions (beating-heart) and during cardiac arrest with automated chest compressions (CC, intra-arrest). METHODS: In a first set of experiments, beating-heart pigs were randomly submitted to conventional mechanical ventilation or hypothermic TLV with perfluoro-N-octane (between 15 and 32 °C). In a second set of experiments, pigs were submitted to ventricular fibrillation and CC. One group underwent continuous CC with asynchronous conventional ventilation (Control group). The other group was switched to TLV while pursuing CC for the investigation of cooling capacities and potential effects on cardiac massage efficiency. RESULTS: Under physiological conditions, TLV significantly decreased the entire body temperatures below 34 °C within only 10 min. As examples, cooling rates averaged 0.54 and 0.94 °C/min in rectum and esophageous, respectively. During cardiac arrest, TLV did not alter CC efficiency and cooled the entire body below 34 °C within 20 min, the low-flow period slowing cooling during CC. CONCLUSION: Using a specifically designed liquid ventilator, TLV induced a very rapid cooling of the entire body in large animals. This was confirmed in both physiological conditions and during cardiac arrest with CC. TLV could be relevant for ultra-rapid cooling independently of body weight.

Evaluation of lung recovery after static administration of three different perfluorocarbons in pigs.

BACKGROUND: The respiratory properties of perfluorocarbons (PFC) have been widely studied for liquid ventilation in humans and animals. Several PFC were tested but their tolerance may depend on the species. Here, the effects of a single administration of liquid PFC into pig lungs were assessed and compared. Three different PFC having distinct evaporative and spreading coefficient properties were evaluated (Perfluorooctyl bromide [PFOB], perfluorodecalin [PFD] and perfluoro-N-octane [PFOC]). METHODS: Pigs were anesthetized and submitted to mechanical ventilation. They randomly received an intra-tracheal administration of 15 ml/kg of either PFOB, PFD or PFOC with 12 h of mechanical ventilation before awakening and weaning from ventilation. A Control group was submitted to mechanical ventilation with no PFC administration. All animals were followed during 4 days after the initial PFC administration to investigate gas exchanges and clinical recovery. They were ultimately euthanized for histological analyses and assessment of PFC residual concentrations within the lungs using dual nuclei fluorine and hydrogen Magnetic Resonance Imaging (MRI). Sixteen animals were included (4/group). RESULTS: In the PFD group, animals tended to be hypoxemic after awakening. In PFOB and PFOC groups, blood gases were not significantly different from the Control group after awakening. The poor tolerance of PFD was likely related to a large amount of residual PFC, as observed using MRI in all lung samples (≈10% of lung volume). This percentage was lower in the PFOB group (≈1%) but remained significantly greater than in the Control group. In the PFOC group, the percentage of residual PFC was not significantly different from that of the Control group (≈0.1%). Histologically, the most striking feature was an alveolar infiltration with foam macrophages, especially in the groups treated by PFD or PFOB. CONCLUSIONS: Of the three tested perfluorocarbons, PFOC offered the best tolerance in terms of lung function, gas exchanges and residuum in the lung. PFOC was rapidly cleared from the lungs and virtually disappeared after 4 days whereas PFOB persisted at significant levels and led to foam macrophage infiltration. PFOC could be relevant for short term total liquid ventilation with a rapid weaning.

Review of novel clinical applications of advanced, real-time, 3-dimensional echocardiography.

Advances in computer processing speed and memory along with the advent of the microbeam former that can sample an entire crystal of the ultrasound transducer made possible the performance of 3-dimensional echocardiography in real time (RT3DE). The miniaturization of a 3-dimensional transducer permitting its extension to transesophageal mode rapidly expanded its use in a variety of conditions. Recent development of user-friendly automated/semiautomated cropping and display software may make it rather simple, even for the novice to gather useful information from RT3DE. We discuss the background, technique, and cutting-edge research and novel clinical applications of advanced RT3DE, including left ventricular dyssynchrony assessment, 3-D speckle tracking, myocardial contrast echocardiography, complete 4-dimensional (4-D) shape and motion analysis of the left ventricle, 4-D volumetric analysis of the right ventricle, 3-D volume rendering of the mitral valve, and other percutaneous and surgical procedural applications.

Therapeutic Hypothermia: What's Hot about Cold.

Reducing body temperature to 33 °C in patients who have been resuscitated from cardiac arrest but who remain comatose can ameliorate anoxic encephalopathy and improve recovery. Experimental animal studies have suggested that cooling to 33 °C also aids the resuscitative process itself, facilitating the resumption of spontaneous circulation (ROSC). The mechanism of cooling benefit is probably the reduction of metabolic demand of most organs, and reduced production of toxic metabolites and reactive oxygen species. External cooling by application of ice or pads through which cold water circulates is effective but requires up to 8 hours to achieve the target temperature of 33 °C. Our goal was to develop a faster method of cooling that could be initiated during cardiopulmonary resuscitation. In anesthetized swine, we induced ventricular fibrillation by passing alternating current down an electrode catheter in the right ventricle. We then ventilated the animals' lungs with liquid perfluorocarbons (PFCs), a technique known as total liquid ventilation (TLV). Perfluorocarbons are oxygen-carrying modules; we pre-oxygenated the PFCs by bubbling 100% O(2) through the solution for 2 minutes before use, and pre-cooled the PFCs to -15 °C. The cold oxygenated PFCs reduced pulmonary artery temperature (a surrogate for myocardial temperature) to 33 °C in about 6 minutes. Using this technique we achieved ROSC in 8 of 11 (82%) animals given TLV versus 3 of 11 (27%) control animals receiving conventional CPR without PFCs (P<0.05). We also compared the cold TLV technique with the administration of intravenous iced saline to achieve hypothermia. Both the cold TLV and cold saline techniques produced rapid hypothermia, but we could achieve ROSC in only 2 of 8 (25%) animals given cold saline versus 7 of 8 (88%) given cold TLV. This result is likely due to the rise in right atrial pressure and corresponding reduction in coronary perfusion pressure caused by volume loading with IV saline, in addition to the higher pO(2) associated with pre-oxygenated PFCs. Cold TLV is a promising technique for achieving rapid intra-arrest and post-resuscitation hypothermia in patients experiencing cardiac arrest.

The impact of prolonged rotary ventricular assist device support upon ventricular geometry and flow kinetics.

BACKGROUND: The aim of this study was to determine the impact of prolonged left ventricular assist device (VAD) support on cardiac ventricular geometry and VAD flow kinetics. METHODS: Nineteen patients with end-stage heart failure underwent the implantation of HeartMate II rotary flow VADs. Left and right ventricular geometry and VAD flow kinetics were assessed by transthoracic echocardiography early (7 ± 1 days) and late (113 ± 21 days) after VAD implantation. RESULTS: Left ventricular end-diastolic internal dimension decreased by 21% and 35%, respectively, early and late after VAD implantation (n = 19; P < .001 vs before VAD implantation). Right ventricular end-diastolic internal dimension did not decrease at either time. Hemodynamic trends were similar. VAD inflow obstruction by myocardium was observed in eight patients, seven of whom demonstrated significantly increased variation of VAD inflow during the cardiac cycle ("pulsatility") detected by Doppler studies. Medical or surgical intervention returned VAD flow patterns toward baseline in seven of eight patients with VAD obstructions. CONCLUSIONS: Prolonged rotary VAD support unloads the left ventricle, with modest effects on the right ventricle. These changes are often associated with alterations of VAD flow kinetics, requiring therapeutic intervention. These findings indicate the usefulness of echocardiographic surveillance in patients undergoing prolonged VAD support.

Part 6: electrical therapies: automated external defibrillators, defibrillation, cardioversion, and pacing: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.

The recommendations for electrical therapies described in this section are designed to improve survival from SCA and life-threatening arrhythmias. Whenever defibrillation is attempted, rescuers must coordinate high-quality CPR with defibrillation to minimize interruptions in chest compressions and to ensure immediate resumption of chest compressions after shock delivery. The high first-shock efficacy of newer biphasic defibrillators led to the recommendation of single shocks plus immediate CPR instead of 3-shock sequences that were recommended prior to 2005 to treat VF. Further data are needed to refine recommendations for energy levels for defibrillation and cardioversion using biphasic waveforms.

Exercise-induced left ventricular systolic dysfunction in women heterozygous for dystrophinopathy.

BACKGROUND: Mutations in the X-linked gene encoding dystrophin cause skeletal and cardiac muscle diseases in men. Female "carriers" also can develop overt disease. The purpose of this study was to ascertain the prevalence of cardiac contractile abnormalities in dystrophinopathy carriers. METHODS: Twenty-four dystrophinopathy heterozygotes and 24 normal women each underwent standard exercise stress echocardiography. RESULTS: Heterozygotes demonstrated mildly lower left ventricular ejection fractions (LVEFs) at rest compared with controls (0.56 + or - 0.10 vs 0.62 + or - 0.07, P = .02). After exercise, the mean LVEF fell to 0.53 + or - 0.14 in heterozygotes but rose to 0.73 + or - 0.07 in controls (P < .001). Twenty-one of 24 dystrophinopathy heterozygotes demonstrated > or = 1 of the following: abnormal resting LVEF, abnormal LVEF response to exercise, or exercise-induced wall motion abnormality. CONCLUSIONS: Women heterozygous for dystrophinopathy demonstrate significant left ventricular systolic dysfunction, which is unmasked by exercise. This finding has mechanistic implications for both inherited and acquired cardiac disease states.

Perfluorocarbon induced intra-arrest hypothermia does not improve survival in a swine model of asphyxial cardiac arrest.

BACKGROUND: Pulseless electrical activity is an important cause of cardiac arrest. Our purpose was to determine if induction of hypothermia with a cold perfluorocarbon-based total liquid ventilation (TLV) system would improve resuscitation success in a swine model of asphyxial cardiac arrest/PEA. METHODS: Twenty swine were randomly assigned to control (C, no ventilation, n=11) or TLV with pre-cooled PFC (n=9) groups. Asphyxia was induced by insertion of a stopper into the endotracheal tube, and continued in both groups until loss of aortic pulsations (LOAP) was reached, defined as a pulse pressure less than 2mmHg. The TLV animals underwent asphyxial arrest for an additional 2min after LOAP, followed by 3min of hypothermia, prior to starting CPR. The C animals underwent 5min of asphyxia beyond LOAP. Both groups then underwent CPR for at least 10min. The endpoint was the resumption of spontaneous circulation maintained for 10min. RESULTS: Seven of 9 animals achieved resumption of spontaneous circulation (ROSC) in the TLV group vs. 5 of 11 in the C group (p=0.2). The mean pulmonary arterial temperature was lower in total liquid ventilation animals starting 4min after induction of hypothermia (TLV 36.3+/-0.2 degrees C vs. C 38.1+/-0.2 degrees C, p<0.0001). Arterial P(O)(2) was higher in total liquid ventilation animals at 2.5min of CPR (TLV 76+/-12mmHg vs. C 44+/-2mmHg; p=0.03). CONCLUSION: Induction of moderate hypothermia using perfluorocarbon-based total liquid ventilation did not improve ROSC success in this model of asphyxial cardiac arrest.