Comparison of different porcine models simulating myocardial cold ischemia of pediatric donor hearts.

BACKGROUND: Our team previously identified a stem cell-derived cardioprotective additive that can be added to standard cardioplegia to extend myocardial viability during prolonged myocardial cold ischemic time (CIT) in rodent models. The purpose of this study was to utilize a porcine model to compare in-vivo versus ex-vivo porcine simulation of CIT that accompanies cardiac transplantation in humans, in order to determine an optimal method for translation of our studies to larger animals. METHODS: Eight 39-55 kg Yorkshire X pigs were randomly assigned to either in-vivo or ex-vivo simulation. After administration of general anesthesia and endotracheal intubation, baseline measurement of left ventricular performance was obtained via transesophageal echocardiography (TEE). After midline sternotomy and heparin administration, the aorta was cross-clamped and two liters of HTK-Custodiol were introduced via the aortic root. The in-vivo method utilized cold ischemic heart storage in the chest cavity while supporting the experimental animal with cardiopulmonary bypass (CPB). The ex-vivo method involved standard cardiac procurement, cold ischemic storage outside of the body, and subsequent cardiac reperfusion utilizing cardiac reanimation in a Langendorff heart perfusion mode. After CIT, measurements of post-ischemic left ventricular performance were obtained via echocardiography. Results are presented as: Mean ± Standard Deviation (Median, Minimum-Maximum). RESULTS: Weight (kilograms) was similar in the in-vivo group and the ex-vivo group: 44 ± 1.8 (44, 42-46) versus 44 ± 5.1 (43.5, 39-51), respectively. Cold ischemic time (minutes) was longer in the ex-vivo group: 360 ± 0 (360, 360-360) versus 141 ± 26.7 (149, 102-163). Temperature (degrees Celsius) was colder in the ex-vivo group: 8 ± 0 (8, 8-8) versus 16.5 ± 4.2 (16, 12-16).In the in-vivo group, baseline ejection fraction and ejection fraction after CIT were: 48.25% ± 14.95% (48.5%, 33%-63%) and 41.25% ± 22.32% (41.5%, 20%-62%), respectively. In the ex-vivo group, baseline ejection fraction and ejection fraction after CIT were: 56.4% ± 5.9% (57%, 50%-67%) and 60.4% ± 7.7% (61.5%, 51.9%-67%), respectively. CONCLUSION: The ex-vivo technique is suitable to evaluate cardioplegia additives that may substantially extend myocardial tolerance to cold ischemia.

George Daicoff: A Pioneering Surgeon and Humanitarian of The Southern Thoracic Surgical Association.

George Daicoff was a true pioneer who excelled in patient care, research, teaching, and advocacy; he performed cardiac surgery on thousands. He trained at Mayo Clinic under the tutelage of John Kirklin in 1966. He served on the faculty at University of Florida from 1967 to 1977 and became Chief of Thoracic and Cardiovascular Surgery at University of Florida. He then served as Chief of Cardiovascular Surgery at All Children's Hospital from 1977 to 1998. In 1972, he was one of 13 founding members of the Congenital Heart Surgeons' Society (CHSS), and in 1973, he was one of 10 surgeons to attend the first meeting of CHSS. Dr Daicoff won the 1970 Southern Thoracic Surgical Association President's Award for best scientific paper, and the 1996 Southern Thoracic Surgical Association Osler Abbot Award. In 2015, the Southern Thoracic Surgical Association Congenital Heart Surgery President's Award was named the George Daicoff Award.

Case report: double lung en bloc procurement from a donor after arterial switch operation.

The growing unmet demand for suitable organ donors increases each year. Despite relative contraindications for thoracic organ donation after previous cardiac surgery, experienced programmes and surgeons can successfully utilise the lungs from select donors who have undergone prior cardiac surgery. This is the first reported case of double lung en bloc procurement from a donor who had a previous arterial switch operation as an infant.

Safe sternal reentry in patients with large thoracic aortic pseudoaneurysms.

Sternal reentry for ascending aorta pseudoaneurysm repair presents a formidable challenge because of the risk of aneurysm rupture and hemorrhage. We describe two cases of large pseudoaneurysms at high risk for rupture during sternal reentry in which the chest was safely entered by use of an anterior sternal retraction technique. Several other methods for sternal reentry have been reported; however, the reliability and efficiency of the described technique make it the preferred method for sternal reentry for pseudoaneurysms at our institution.

Close antiplatelet therapy monitoring and adjustment based upon thrombelastography may reduce late-onset bleeding in HeartMate II recipients.

OBJECTIVES: Bleeding is the most common complication of HeartMate II and is partially attributable to platelet dysfunction; however, antiplatelet therapy is arbitrary in most centres. We investigated how antiplatelet therapy adjustment with thrombelastography affects late-onset bleeding. METHODS: Thrombelastography was used to adjust antiplatelet therapy in 57 HeartMate II recipients. Kaplan-Meier survival curves and Cox proportional hazard ratio model were used to identify predictors of late-onset bleeding in univariate and multivariate analysis. Finally, late-onset bleeding rate in our study was compared with the reported rates in other studies in the literature, all of which did not use any test to monitor or adjust antiplatelet therapy. RESULTS: Mean follow-up was 347 days. Eighteen late-onset bleeding events occurred in 12 patients, a late-onset bleeding rate of 12/57 (21%) or 0.21 events/patient-year. The Kaplan-Meier survival curves demonstrated that late-onset bleeding was more common in the destination therapy cohort (P = 0.02), in patients older than 60 years (P = 0.04) and in females (P = 0.01), none of which was significant in multivariate analysis at a significance level of 0.05. To further investigate the higher bleeding rate in elderly patients, thrombelastography parameters were compared between younger and older patients at the age cut-off of 60 years which demonstrated a prothrombotic change the day after device implantation in younger patients that was absent in the elderly. There was also a trend towards higher requirement for antiplatelet therapy in younger patients while on device support, but the difference did not reach statistical significance. The average late-onset or gastrointestinal bleeding rate among seven comparable studies in the literature that did not use any monitoring test to adjust antiplatelet therapy was 0.49 events/patient-year. CONCLUSIONS: Our study implicates that antiplatelet therapy adjustment with thrombelastography may reduce late-onset bleeding rate in HeartMate II recipients. Bleeding was more common in the elderly recipients and analysis of thrombelastography data suggests that a less aggressive antiplatelet therapy regimen could potentially lower bleeding rate in this vulnerable population.

Technical pearls for swine lung transplantation.

BACKGROUND: Since the advent of ex vivo lung perfusion (EVLP), there has been increased focus on swine models of lung transplantation; however, the anatomic differences between human and swine lungs and the technical challenges in performing porcine lung transplantation are not well described in the surgical literature. METHODS: Surgically important anatomic variations are described, and the technical measures taken to address them during harvest and transplantation are introduced. RESULTS: There are three surgically important anatomic variations in pigs. First, the right cranial lobe bronchus arises directly from the trachea, which makes right lung transplantation technically challenging if not prohibitive. Second, the left hemi-azygos vein is fully developed and courses upward through the posterior mediastinum, where it crosses the left pulmonary hilum and drains directly into the coronary sinus. During transplantation, this vein is ligated and dissected away to expose the underlying left pulmonary hilar structures. Third, the right inferior pulmonary vein crosses the midline to drain into the left atrium immediately adjacent to the left inferior pulmonary vein. During donor lung preparation, the right inferior pulmonary vein is ligated distally from the left atrium, which leaves an adequate atrial cuff around the left sided pulmonary veins for later anastomosis. CONCLUSION: Experimental porcine lung transplantation is technically demanding. We have found recognition of the above described anatomical differences and technical nuances facilitate transplantation and provide reproducible results.

Discrepancies between clinical and autopsy diagnoses in lung transplant recipients.

We sought to investigate the role of autopsy diagnoses in lung transplantation by comparing the clinically derived cause of death with autopsy deduced cause of death in a cohort of lung transplant recipients. We retrospectively reviewed all consecutive autopsy findings on lung transplant recipients transplanted between March 1994 and March 2007. We reviewed medical records and our lung transplant database to determine the clinical diagnosis of cause of death based on the clinical assessment and discharge summary at the time of death. Our study showed that 21% of the autopsies performed on lung transplant recipients at our institution revealed findings unsuspected at the time of death. Myocardial infarction, pulmonary embolism, high grade acute cellular rejection and infections were the most frequently missed diagnoses. The autopsy remains a useful tool in confirming diagnostic accuracy in lung transplant recipients.

Ventricular assist device implantation in the pediatric population: does pump size selection and associated hemodynamics impact outcomes?

The use of pediatric ventricular assist devices (VADs) continues to evolve with the availability of smaller blood pumps. We examine the correlation of implanting appropriate sized blood pumps with a lower incidence of VAD related complications (VADRC). A 7-year retrospective review was undertaken for all pediatric VAD patients. Optimal VAD hemodynamics were defined as cardiac index of 2.7 L/m2 and rate of 80 beats per minute (bpm) with complete fill/empty of the blood pump. Patient/blood pump size match, VAD rate and fill/empty ratios were calculated (optimum = 1.0) and then correlated with incidence of VADRC. The study included 22 patients, mean age 9.77 years (6 mo-18 yrs) and mean body surface area (BSA) of 1.14 m2 (0.14 m2-2.32 m2), who underwent VAD implantation. VADRC included death while on support (n = 5), bleeding requiring reoperation (n = 8), hemolysis (n = 2), neurologic events (n = 2), thrombus formation (n = 3), and infection (n = 3). Six patients were bridged to transplant without any VADRC. This subset of patients had a mean blood pump size match ratio of 0.98, VAD rate ratio of 0.92 and fill/empty ratio of 1.00. Patients with VADRC (n = 16) were found to have a mean blood pump size match ratio of 0.72, VAD rate ratio of 0.72 and fill/empty ratio of 0.78. We report a series of pediatric patients with wide ranging BSA receiving VAD implantation. Selection of appropriate sized blood pumps can be correlated with decreased VADRC.

Late unilateral pulmonary edema in single lung transplant recipients.

In this study we describe 3 single lung transplant recipients who developed unilateral pulmonary edema in the setting of cardiac and renal dysfunction. All 3 patients responded to diuresis with clinical and radiographic improvement. Unilateral cardiogenic pulmonary edema should be considered in the differential diagnosis of dyspnea and unilateral radiographic infiltrates in single lung transplant recipients.

Intraoperative contralateral pneumothorax during single-lung transplantation.

Contralateral intraoperative tension pneumothorax is a rare complication of thoracic surgical procedures. Here we present three cases of tension pneumothorax that developed during single-lung transplantation for emphysema and pulmonary fibrosis. To the best of our knowledge, this is only the second report of contralateral intraoperative tension pneumothorax during single-lung transplantation. A high index of clinical suspicion is required for the detection of this potentially catastrophic complication.

Effect of sildenafil on pulmonary artery pressure, systemic pressure, and nitric oxide utilization in patients with left ventricular assist devices.

BACKGROUND: Pulmonary artery hypertension can complicate the early postoperative care of patients with left ventricular assist devices (LVADs). Inhaled nitric oxide (INO) is frequently used to manipulate pulmonary resistance after LVADs have been placed. We evaluated the effect of oral sildenafil therapy on pulmonary artery pressure, systemic pressure, and nitric oxide utilization. METHODS: After Institutional Review Board approval, the records of 10 consecutive adult patients with LVADs and pulmonary hypertension who received sildenafil were reviewed. Demographics, surgical history, INO use, inotrope requirements, and hemodynamic response to oral sildenafil at multiple intervals were collected. Hemodynamic data were analyzed with a two-way analysis of variance of repeated measures with correction for multiple comparisons. RESULTS: There were 8 men and 2 women with 6 Heartmate XVE LVADs and 4 Thoratec LVADs (both, Thoratec, Pleasanton, California). When weaning was attempted, 8 patients who received INO demonstrated rebound pulmonary hypertension or increased right heart dysfunction. All patients were on inotropic therapy with dobutamine and milrinone. Sildenafil produced a significant reduction in pulmonary artery systolic pressure within 90 minutes of oral administration (p = 0.042). Significant changes in systolic blood pressure, mean arterial pressure, systemic vascular resistance, and heart rate were not observed. All 8 patients receiving INO were weaned within 12 hours without recurrent pulmonary hypertension. All 10 patients were weaned from inotropic support within 72 hours. No patient suffered right-side heart failure requiring intervention. CONCLUSIONS: Oral sildenafil represents a useful adjunctive therapy for patients with LVADs. In our series, it provided additional reduction of pulmonary artery pressure, and facilitated weaning from INO and inotropes without deleterious hemodynamic consequences.

Managing the post-left ventricular assist device patient.

The implantation of ventricular assist devices allows the opportunity for patients with intractable heart failure to have improved quality and quantity of life. The devices may be implanted after failed attempts to wean from bypass, as a bridge to transplantation, or as destination therapy. Key issues following the implantation of assist devices include the prevention of right ventricular failure, appropriate pharmacologic management, prevention and management of infection, and detection and treatment of device dysfunction.

Comamonas (Pseudomonas) testosteroni endocarditis.

Comamonas testosteroni has rarely been implicated as a human pathogen. We report a case of infectious endocarditis due to this organism, occurring in a 49-year-old man. The posterior leaflet of the mitral valve contained a 1 x 1 cm vegetation and showed myxoid degeneration and acute inflammation. The patient had no evidence of reinfection after 32 months. The infection was almost certainly community acquired, as is usually true for this organism.

Oral sildenafil reduces pulmonary hypertension after cardiac surgery.

BACKGROUND: Treatment of postoperative pulmonary hypertension with intravenous (IV) pulmonary vasodilators is hampered by the lack of selectivity. Inhaled nitric oxide produces selective pulmonary vasodilation; however, it requires a special device, and weaning can cause rebound. Oral sildenafil is a phosphodiesterase type V inhibitor. Sildenafil can produce sustained pulmonary vasodilatation in patients with hypoxic or primary pulmonary hypertension; however, experience with postoperative pulmonary hypertension is limited. We report our initial experience with eight patients who received oral sildenafil as adjunctive therapy for postoperative pulmonary hypertension METHODS: We reviewed the charts of eight adult patients with postoperative pulmonary hypertension who received oral sildenafil (25 to 50 mg) to facilitate weaning of IV (milrinone, nitroglycerine, and sodium nitroprusside) and inhaled (nitric oxide) pulmonary vasodilators. Hemodynamic data were recorded before and 30 and 60 minutes after the initial dose of sildenafil. RESULTS: After the initial dose of sildenafil, mean pulmonary artery pressure was reduced by 20% and 22% at 30 and 60 minutes, respectively (p < 0.05). Pulmonary vascular resistance index decreased by 49% and 44% at 30 and 60 minutes, respectively (p < 0.05). Sildenafil had no clinically significant effects on cardiac index, mean arterial pressure, or systemic vascular resistance. Subsequent doses of sildenafil were administered at regular intervals, allowing successful weaning of concomitant pulmonary vasodilators. CONCLUSIONS: Oral sildenafil is an effective agent for treatment of postoperative pulmonary hypertension and can be used to facilitate weaning of inhaled and IV pulmonary vasodilators.

Measurement of cardiac output before and after cardiopulmonary bypass: Comparison among aortic transit-time ultrasound, thermodilution, and noninvasive partial CO2 rebreathing.

OBJECTIVES: A noninvasive continuous cardiac output system (NICO) has been developed recently. NICO uses a ratio of the change in the end-tidal carbon dioxide partial pressure and carbon dioxide elimination in response to a brief period of partial rebreathing to measure CO. The aim of this study was to compare the agreement among NICO, bolus (TDCO), and continuous thermodilution (CCO), with transit-time flowmetry of the ascending aorta using an ultrasonic flow probe (UFP) before and after cardiopulmonary bypass (CPB). DESIGN: Prospective, observational human study. SETTING: Veterans Affairs Medical Center Hospital. PARTICIPANTS: Sixty-eight patients. METHODS: Matched sets of CO measurements between NICO, TDCO, CCO, and UFP were collected in 68 patients undergoing elective CABG at specific time periods before and after separation from CPB. After anesthetic induction, all patients had an NICO sensor attached between the endotracheal tube and the breathing circuit, a PAC floated into the pulmonary artery for TDCO and CCO monitoring, and a UFP positioned on the ascending aorta and used for the reference CO. Bland-Altman analysis was used to compare the agreement among the different methods. MEASUREMENTS AND MAIN RESULTS: Bland-Altman analysis of CO measurements before CPB yielded a bias, precision, and percent error of 0.04 L/min +/- 1.07 L/min (44.8%) for NICO, 0.18 L/min +/- 1.01 L/min (41.7%) for TDCO, and 0.29 L/min +/- 1.40 L/min (57.5%) for CCO compared with simultaneous UFP CO measurements, respectively. After separation from CPB (average 29 mins), bias, precision, and percent error were -0.46 L/min +/- 1.06 L/min (37.3%) for NICO, 0.35 L/min +/- 1.39 L/min (46.1%) for TDCO, and 0.36 L/min +/- 1.96 L/min (64.7%) for CCO compared with UFP CO measurements, respectively. CONCLUSIONS: Before initiation of CPB, the accuracy for all 3 techniques was similar. After separation from CPB, the tendency was for NICO to underestimate CO and for TDCO and CCO to overestimate it. NICO offers an alternative to invasive CO measurement.