Pulmonary endothelial dysfunction after cardiopulmonary bypass in neonatal pigs

Pulmonary hypertension associated with cardiopulmonary bypass and cardiac surgery

BACKGROUND AND AIM

Pulmonary hypertension (PH) is frequently associated with cardiovascular surgery and is a common complication that has been observed after surgery utilizing cardiopulmonary bypass (CPB). The purpose of this review is to explain the characteristics of PH, the mechanisms of PH induced by cardiac surgery and CPB, treatments for postoperative PH, and future directions in treating PH induced by cardiac surgery and CPB using up-to-date findings.

METHODS

The PubMed database was utilized to find published articles.

RESULTS

There are many mechanisms that contribute to PH after cardiac surgery and CPB which involve pulmonary vasomotor dysfunction, cyclooxygenase, the thromboxane A2 and prostacyclin pathway, the nitric oxide pathway, inflammation, and oxidative stress. Furthermore, there are several effective treatments for postoperative PH within different types of cardiac surgery.

CONCLUSIONS

By possessing a deep understanding of the mechanisms that contribute to PH after cardiac surgery and CPB, researchers can develop treatments for clinicians to use which target the mechanisms of PH and ultimately reduce and/or eliminate postoperative PH. Additionally, learning about the most up-to-date studies regarding treatments can allow clinicians to choose the best treatments for patients who are undergoing cardiac surgery and CPB.

Aprotinin Impacts 8-Isoprostane after Coronary Artery Bypass Grafting

BACKGROUND AND AIMS:

The lungs participate in the modulation of the circulating inflammatory factors induced by coronary artery bypass grafting. We investigated whether aprotinin-which has been suggested to interact with inflammation-influences lung passage of key inflammatory factors after coronary artery bypass grafting.

MATERIAL AND METHODS:

A total of 40 patients undergoing coronary artery bypass grafting were randomized into four groups according to aprotinin dose: (1) high dose, (2) early low dose, (3) late low dose, and (4) without aprotinin. Pulmonary artery and radial artery blood samples were collected for the evaluation of calculated lung passage (pulmonary artery/radial artery) of the pro-inflammatory factors interleukin 6 and interleukin 8, 8-isoprostane, myeloperoxidase and the anti-inflammatory interleukin 10 immediately after induction of anesthesia (T1), 1 min after releasing aortic cross clamp (T2), 15 min after releasing aortic cross clamp (T3), 1 h after releasing aortic cross clamp (T4), and 20 h after releasing aortic cross clamp (T5).

RESULTS:

Pulmonary artery/radial artery 8-isoprostane increased in patients with high aprotinin dose as compared with lower doses (1.1 range 0.97 vs 0.9 range 1.39, p = 0.001). The main effect comparing high aprotinin dose with lower doses was significant (F(1, 38) = 7.338, p = 0.01, partial eta squared = 0.16) further supporting difference in the effectiveness of high aprotinin dose for pulmonary artery/radial artery 8-isoprostane.

CONCLUSION:

According to the pulmonary artery/radial artery equation, the impact of aprotinin on 8-isoprostane after coronary artery bypass grafting is dose dependent. Aprotinin may aid the lung passage of circulating factors toward a beneficial anti-inflammatory milieu.

The Impact of Lung Ventilation on Some Cytokines after Coronary Artery Bypass Grafting

Background and Aims:

Cardiopulmonary bypass induces a systematic inflammatory response, which is partly understood by investigation of peripheral blood cytokine levels alone; the lungs may interfere with the net cytokine concentration. We investigated whether lung ventilation influences lung passage of some cytokines after coronary artery bypass grafting.

Material and Methods:

In total, 47 patients undergoing coronary artery bypass grafting were enrolled, and 37 were randomized according to the ventilation technique: (1) No-ventilation group, with intubation tube detached from the ventilator; (2) low tidal volume group, with continuous low tidal volume ventilation; and (3) continuous 10 cm H2O positive airway pressure. Ten selected patients undergoing surgery without cardiopulmonary bypass served as a referral group. Representative pulmonary and radial artery blood samples were collected for the evaluation of calculated lung passage (pulmonary/radial artery) of the pro-inflammatory cytokines (interleukin 6 and interleukin 8) and the anti-inflammatory interleukin 10 immediately after induction of anesthesia (T1), 1 h after restoring ventilation/return of flow in all grafts (T2), and 20 h after restoring ventilation/return of flow in all grafts (T3).

Results:

Pulmonary/radial artery interleukin 6 and pulmonary/radial artery interleukin 8 ratios ( p = 0.001 and p = 0.05, respectively) decreased, while pulmonary/radial artery interleukin 10 ratio ( p = 0.001) increased in patients without cardiopulmonary bypass as compared with patients with cardiopulmonary bypass.

Conclusions:

The pulmonary/radial artery equation is an innovative means for the evaluation of cytokine lung passage after coronary artery bypass grafting. The mode of lung ventilation has no impact on some cytokines after coronary artery bypass grafting in patients treated with cardiopulmonary bypass.

Managing the inflammatory response after cardiopulmonary bypass: review of the studies in animal models

Objective

To review studies performed in animal models that evaluated therapeutic interventions to inflammatory response and microcirculatory changes after cardiopulmonary bypass.

Methods

It was used the search strategy ("Cardiopulmonary Bypass" ^(MeSH)) and ("Microcirculation" ^(MeSH) or "Inflammation" ^(MeSH) or "Inflammation Mediators" ^(MeSH)). Repeated results, human studies, non-English language articles, reviews and studies without control were excluded.

Results

Blood filters, system miniaturization, specific primers regional perfusion, adequate flow and temperature and pharmacological therapies with anticoagulants, vasoactive drugs and anti-inflammatories reduced changes in microcirculation and inflammatory response.

Conclusion

Demonstrated efficacy in animal models establishes a perspective for evaluating these interventions in clinical practice.

Use of a simply modified drainage catheter for peritoneal dialysis treatment of acute renal failure associated with cardiac surgery in infants

Acute renal failure (ARF) is a common complication in infants who undergo cardiac surgery in the intensive care unit. We report on a modified drainage catheter used in peritoneal dialysis (PD) for the treatment of ARF associated with cardiac surgery in infants. Thirty-nine infants with congenital heart disease undergoing cardiac surgery who developed ARF at our center between January 2009 and January 2012 were assessed. A modified drainage catheter for PD was used in these infants. Their demographic, clinical, and surgical data were analyzed. Thirty infants with ARF were cured by PD, and the other 9 died in the first 48 hours because of the severity of the acute cardiac dysfunction. All these infants were dependent upon mechanical ventilation during the postoperative period and used vasoactive drugs. In the survival group, the interval between the procedure and initiation of PD was 13.6 ± 6.5 (range, 6-30) hours. PD duration was 3.9 ± 0.9 (3-6) days. Minor complications were encountered in some patients (asymptomatic hypokalemia, hyperglycemia, and thrombocytopenia). These complications were readily treated by drugs or resolved spontaneously. Hemodynamics, cardiac function, and renal function improved significantly during PD. These data suggest that PD using a modified drainage catheter for ARF after cardiac surgery in infants is safe, feasible, inexpensive, and yields good results.

Postoperative use of oral sildenafil in pediatric patients with congenital heart disease

We sought to determine the efficacy of postoperative oral sildenafil therapy (OST) in pediatric patients with congenital heart disease (CHD). A retrospective review of 45 postoperative patients with CHD who received OST was performed. Patients were categorized into three groups according to clinical indications: (1) to stabilize pulmonary vascular reactivity after biventricular repair (group 1 [n = 15]), (2) to lower pulmonary vascular resistance after bidirectional cavopulmonary shunt (group 2 [n = 12]), and (3) to improve post-Fontan hemodynamics (group 3 [n = 18]). Thirty-four patients (34 of 45 [75.6%]) had received inhaled nitric oxide (iNO) while on OST. Mean pulmonary arterial pressure (mPAP), mean systemic blood pressure (mSBP), and peripheral oxygen saturation (SpO(2)) were recorded during the first 24 hours after the initiation of OST. In group 1, the baseline mPAP/mSBP ratio (0.60 +/- 0.17) decreased significantly after the second (0.46 +/- 0.14, p = 0.004) and fourth (0.50 +/- 0.18, p = 0.025) doses of OST. In group 2, baseline SpO(2) (71.0 +/- 12.3%) increased after the fourth dose (75.1 +/- 12.3%, p = 0.04) of OST, without significant changes in mPAP. In group 3, baseline mPAP (14.8 +/- 3.3 mmHg) decreased significantly after the first (13.9 +/- 2.8 mmHg, p = 0.025) and second (13.3 +/- 1.9 mmHg, p = 0.016) doses of OST, without changes in SpO(2). In thirty-one (31 of 34 [92%]) subjects, iNO was discontinued within a median of 2 days after the initiation of OST, without rebound phenomena. There were no OST-related complications. Sildenafil citrate can be used safely in postoperative pediatric patients with CHD. Benefits from OST may be manifested differently in various clinical settings.

Periodic acceleration (pGz) CPR in a swine model of asphyxia induced cardiac arrest. Short-term hemodynamic comparisons

BACKGROUND

Asphyxia is one of the most common causes of pediatric cardiac arrest, and becoming a more frequently recognized cause in adults. Periodic acceleration (pGz) is a novel method of cardiopulmonary resuscitation (CPR). pGz is achieved by rapid motion of the supine body headward-footward that generates adequate perfusion and ventilation during cardiac arrest. In a swine ventricular fibrillation cardiac arrest model, pGz produced a higher return of spontaneous circulation (ROSC), superior neurological outcome, less echocardiography evidence of post resuscitation myocardial stunning, and decreased indices of tissue injury. In contrast to standard chest compression CPR, pGz does not produce rib fractures. We investigated the feasibility of pGz in severe asphyxia cardiac arrest and assessed whether beneficial effects seen in the VF model of cardiac arrest could be realized.

METHODS AND RESULTS

Sixteen swine weight 4+/-1 kg were anesthetized, tracheally intubated, and instrumented to measure, hemodynamics and echocardiography. Asphyxia was induced by occlusion of the tracheal tube. After loss of aortic pulsations (median time 10 min) animals were observed for three additional minutes following which all were in cardiac arrest. The animals were then randomized to receive 10 min of pGz or standard chest compression ventilation performed with a commercial device (Thumper). A single dose of epinephrine (adrenaline) and sodium bicarbonate were given and defibrillation attempted if appropriate for a maximum of 10 min. Both groups received fractional inspired O2 concentration of 100% during CPR and after resuscitation. Four animals in each group (50%) had an initial ROSC, however only two of the four initial survivors remained alive 3h after ROSC. There were no significant differences in blood pressure, coronary perfusion pressure during CPR and after early ROSC between groups. pGz treated animals had significantly lower pulmonary artery pressure; 20+/-4 mmHg compared to Thumper 46+/-5 mmHg, 30 min after ROSC (p<0.01). Surviving animals in both groups had severe myocardial dysfunction at 30 min after ROSC. At necropsy, 25% of the Thumper treated animals had rib fractures, while none occurred in the pGz group.

CONCLUSIONS

In a lethal model of asphyxia cardiac arrest, pGz is equivalent to standard CPR, with respect to acute outcomes and resuscitation survival rates but is associated with significantly lower pulmonary artery pressures and does not produce traumatic rib fractures.

Risk factors for acute renal failure requiring dialysis after surgery for congenital heart disease in children

BACKGROUND

Limited data exist on the risk factors for acute renal failure (ARF) following cardiac surgery in children with congenital heart disease. This cohort study was conducted to examine this subject, as well as changes in the incidence of ARF from 1993 to 2002, the in-hospital mortality and the time spent in the intensive care unit (ICU).

METHODS

One thousand, one hundred and twenty-eight children, operated on for congenital heart disease between 1993 and 2002, were identified from our prospectively collected ICU database to obtain data on potential risk factors.

RESULTS

A total of 130 children (11.5%) developed ARF after surgery. A young age [> or =1.0 vs. <0.1 year; odds ratio (OR), 0.23; 95% confidence interval (CI), 0.12-0.46], high Risk Adjusted Classification of Congenital Heart Surgery (RACHS-1) score (OR, 2.72; 95% CI, 1.66-4.45) and cardiopulmonary bypass (CPB) (<90 min vs. none; OR, 2.68; 95% CI, 1.03-6.96; > or =90 min vs. none; OR, 12.94; 95% CI, 5.46-30.67) were independent risk factors for ARF. The risk of ARF decreased during the study period. Children with ARF spent a significantly longer time in the ICU (2-7 days vs. <2 days, P = 0.002; > or =7 days vs. <2 days, P < 0.001) compared with non-ARF patients, and showed increased in-hospital mortality (20% vs. 5%, P < 0.001).

CONCLUSION

A young age, high RACHS-1 score and CPB were independent risk factors for ARF after surgical procedures for congenital heart disease in children. The risk of ARF decreased during the study period. Children with severe ARF spent a longer time in the ICU, and the mortality in ARF patients was higher than that in non-ARF patients.

Oral Sildenafil Ameliorates Impaired Pulmonary Circulation Early After Bidirectional Cavopulmonary Shunt

We report a case of successful administration of oral sildenafil (ie, a phosphodiesterase-5 inhibitor) in an infant for impaired pulmonary circulation that caused early clinical deterioration after a bicavopulmonary shunt. The transpulmonary pressure gradient (ie, a clinical indicator of pulmonary circulation) was initially normalized by inhaled nitric oxide; however, an increase in transpulmonary pressure gradient and oxygen desaturation occurred after extubation and discontinuation of inhaled nitric oxide on postoperative day 1. Subsequent administration of oral sildenafil in stepwise doses resulted in normalization of transpulmonary pressure gradient and improved oxygen saturation with successful discontinuation of intravenous vasodilators. Our results suggest that oral sildenafil may be a potent adjunctive therapy for impaired postoperative pulmonary circulation after right heart bypass surgery.

Inhaled iloprost in eight heart transplant recipients presenting with post-bypass acute right ventricular dysfunction

BACKGROUND

During heart transplantation, weaning from cardiopulmonary bypass may be particularly laborious as a result of superimposed acute right ventricular dysfunction in the setting of pre-existing pulmonary hypertension. Research in recent years has focused on inhaled vasodilatory treatment modalities which selectively target the pulmonary circulation.

METHODS

We present a series of eight patients in whom inhaled iloprost, a synthetic prostacyclin analog, was used to treat pulmonary hypertension and right ventricular dysfunction detected by transesophageal echocardiography during a heart transplant procedure. In addition to conventional inotropic support, 20 mug of inhaled iloprost was administered via nebulized aerosol for a 20-min period. Complete sets of hemodynamic measurements were obtained before inhalation and during and after cessation of the inhalation period.

RESULTS

Inhaled iloprost decreased the transpulmonary gradient at the end of the inhalation period relative to baseline (8.2 +/- 1.6 mmHg vs. 11.2 +/- 0.9 mmHg, P < 0.05). The mean pulmonary artery pressure to systemic artery pressure ratio decreased over this period (0.24 +/- 0.07 vs. 0.44 +/- 0.09, P < 0.05). A statistically significant decrease in the pulmonary vascular resistance to systemic vascular resistance ratio was also observed (0.10 +/- 0.02 vs. 0.19 +/- 0.02, P < 0.05). Improved indices of right ventricular function were observed in echocardiographic monitoring.

CONCLUSION

During heart transplantation procedures, episodes of pulmonary hypertension can be successfully treated with inhaled iloprost administration, without untoward side-effects or significant systemic impact.

Neutrophil and platelet dynamics at organ level after cardiopulmonary bypass: an in vivo study in neonatal pigs

The aim was to investigate if organ dysfunction is a consequence of cell accumulation in the tissue and whether this accumulation is caused by the cardiopulmonary bypass (CPB) procedure. Twenty-six piglets were used in the sham group (sternotomy, n=12) or in the CPB group (sternotomy, CPB, n=14). Isotope-labeled autologous (99m)Tc-neutrophils (PMNs) and (111)In-platelets were infused and dynamically followed at organ level with a gamma camera before, during, and 4 h after termination of CPB. The CPB group showed a 49% increase in (99m) Tc-PMNs in the kidneys in the postoperative period compared to a decrease of 2% in the sham group. A less marked decrease was observed in the lungs and peripheral blood between the two groups. The increased radioactivity at organ level post-CPB could be due to changes in flow, extraction in the organ or accumulation of cells, especially in the kidneys and lungs, and might contribute to temporary organ dysfunction postoperatively.