Linda Mongero

Totally Endoscopic Atrial Septal Defect Repair With Robotic Assistance

Background—Computer (robotic) enhancement had emerged as a facilitator of minimally invasive cardiac surgery, and has been used to perform portions of intracardiac procedures via thoracotomy incisions. This report describes the next step in this progression—the first U.S. application of robotic technology for totally endoscopic open heart surgery. Methods and Results—Seventeen patients underwent repair of a secundum-type atrial septal defect (n=12) or patent foramen ovale (n=5) by a totally endoscopic approach, utilizing the Da Vinci robotic system. Cardiopulmonary bypass (CPB) was achieved peripherally. Cardioplegia was administered via the distal port of the arterial cannula after endo-balloon inflation. Via three port incisions in the right chest, pericardiotomy, bicaval occlusion, atriotomy, atrial septopexy, and atrial closure were performed by a surgeon seated at a computer console. A fourth 15-mm port was utilized for suction and suture passage by a patient-side assistant. The mean age of the patients was 47 years (range, 22 to 68). Aortic crossclamp time was 32 minutes (median), and CPB time was 122 minutes. In 16 patients, transesophageal echocardiography after 30 days confirmed successful repair. In one patient, a recurrent shunt was identified and repaired on postoperative day 5. Median length of stay (LOS) in the intensive care unit was 20 hours, and median hospital length of stay was 4 days. Conclusions—Robotic technology can be utilized to perform open heart procedures safely and effectively via totally endoscopic approaches. This technique represents an option for patients seeking a reliable ASD repair but wishing to avoid sternotomy or thoracotomy.

Isolated Cerebral Hypothermia by Single Carotid Artery Perfusion of Extracorporeally Cooled Blood in Baboons

OBJECTIVE Hypothermia has been demonstrated to protect the brain from ischemic or traumatic injury. Previous efforts to induce cerebral hypothermia have relied on techniques requiring total body cooling that have resulted in serious cardiovascular derangements. A technique to selectively cool the brain, without systemic hypothermia, may have applications for the treatment of neurological disease. METHODS After induction of general anesthesia in 12 baboons, the right common carotid artery and ipsilateral femoral artery were each occlusively cannulated and joined to a centrifugal pump. In a closed-circuit system, blood was continually withdrawn from the femoral artery, cooled by water bath, and infused through the common carotid artery with its external branches occluded. Pump flow was varied so that right carotid pressure approximated systemic blood pressure. In six animals, perfusate was cooled to decrease right cerebral temperature to < 19 degrees C for 30 minutes. In six animals, right cerebral temperature was decreased to < 25 degrees C for 3 hours. In those six animals, 133Xe was injected into the right carotid artery before, during, and after hypothermia. Peak radioactivity and washout curves were recorded from bilateral cranial detectors. Systemic warming was accomplished by convective air and warm water blankets. Esophageal, rectal, and bilateral cerebral temperatures were continuously recorded. RESULTS In animals cooled to < 19 degrees C, right cerebral temperature decreased from 34 degrees C to 18.5 +/- 1.1 degrees C (mean +/- standard deviation), P < 0.01, in 26 +/- 13 minutes. Simultaneously, left cerebral temperature decreased to 20.7 +/- 1.6 degrees C. During 30 minutes of stable cerebral hypothermia, esophageal temperature decreased from 35.1 +/- 2.3 degrees C to 34.2 +/- 2.2 degrees C, P < 0.05. In animals cooled to < 25 degrees C, right cerebral temperature decreased from 34 degrees C to 24.5 +/- 0.6 degrees C in 12.0 +/- 6.0 minutes, P < 0.01. Simultaneously, left cerebral temperature decreased to 26.3 +/- 4.8 degrees C. After 3 hours of stable cerebral hypothermia, esophageal temperature was 34.4 +/- 0.5 degrees C, P < 0.05. Right hemispheric cerebral blood flow decreased during hypothermia (26 +/- 16 ml/min/100 g) compared to values before and after hypothermia (63 +/- 29 and 51 +/- 34 ml/min/100 g, respectively; P < 0.05). Furthermore, hypothermic perfusion resulted in a proportionally increased radioactivity peak detected in the left cerebral hemisphere after right carotid artery injection of 133Xe (0.8 +/- 0.2:1, left:right) compared to normothermia before and after hypothermia (0.3 +/- 2 and 0.3 +/- 1, respectively; P < 0.05). Normal heart rhythm, systemic arterial blood pressure, and arterial blood gas values were preserved during hypothermia in all animals. CONCLUSION Bilateral cerebral deep or moderate hypothermia can be induced by selective perfusion of a single internal carotid artery, with minimal systemic cooling and without cardiovascular instability. This global brain hypothermia results from profoundly altered collateral cerebral circulation during artificial hypothermic perfusion. This technique may have clinical applications for neurosurgery, stroke, or traumatic brain injury.

Insertion of bicaval dual lumen extracorporeal membrane oxygenation catheter with image guidance.

Correct placement of the Avalon Elite Bicaval Dual Lumen catheter (Avalon Laboratories, LLC, CA) for single-site venovenous extracorporeal membrane oxygenation (VV ECMO) is safe using image guidance. Using this technique, 26 of 27 patients (96%) had uneventful placement of the cannula in the right internal jugular vein. One patient had a superior vena cava injury during serial dilation, and another patient required cannula repositioning for improved flows. We recommend using both fluoroscopy and transesophageal echocardiogram (TEE) for training purposes or during initial use of the Avalon Elite. As proficiency improves, TEE at the bedside provides an excellent standard of care. Double-lumen ECMO catheters can be effectively placed under image guidance with minimal need for repositioning.

Safe transport of critically ill adult patients on extracorporeal membrane oxygenation support to a regional extracorporeal membrane oxygenation center.

Patients with severe cardiac or pulmonary failure who require transport to specialized hospitals currently pose a challenge. Mechanical support in the form of extracorporeal membrane oxygenation (ECMO) may increase the safety of transporting such patients to an institution where they will have access to advanced medical therapy. Over 2.5 years, 17 patients were successfully cannulated and placed on a simplified ECMO circuit at other institutions and transported via ambulance to our hospital. Fourteen patients with acute respiratory distress syndrome (ARDS) were placed on venovenous (VV) ECMO. Two patients with isolated cardiogenic shock and one patient with ARDS were placed on venoarterial (VA) ECMO. The two cardiogenic shock patients were converted to a biventricular assist device shortly after arrival. The median unit-to-unit transport time was 60 minutes (interquartile range 50–92 minutes), and the median distance traveled was 23 miles (interquartile range 17–55 miles). There was no transport-related morbidity or mortality. The median duration of ECMO support was 8 days (interquartile range 4–11 days). Thirteen patients (76%) were successfully decannulated. Ten patients (59%) were weaned from the ventilator, and nine patients (53%) survived up to 3 months and were discharged from the hospital. Critically ill patients with severe ARDS or cardiogenic shock can be safely transported on VV or VA ECMO support to regional ECMO centers. As the indications and demands for ECMO support expand, so will the role for transporting patients on ECMO.

Safety and efficacy of aprotinin under conditions of deep hypothermia and circulatory arrest

Aprotinin has been successfully used to reduce blood loss and blood product requirements in patients undergoing primary and reoperative cardiac operations. Its safety and efficacy during profound hypothermia and circulatory arrest have been questioned, however. A retrospective review compared 24 patients who received aprotinin during complex aortic procedures under profound hypothermia and circulatory arrest with 24 age-matched patients undergoing similar procedures without aprotinin. Activated clotting time was maintained at longer than 500 seconds (kaolin activating agent) or longer than 750 seconds (celite). We observed no statistically significant difference in the incidence of neurologic events (p not significant) or myocardial infarctions (p not significant), and there was a trend toward reduced in-hospital mortality rate in aprotinin-treated patients. A higher incidence of postoperative renal dysfunction was encountered in aprotinin-treated patients. Aprotinin recipients had a significant reduction in requirements for postoperative homologous erythrocytes (p = 0.01). We conclude that aprotinin may be safely and effectively used in patients undergoing deep hypothermia and circulatory arrest.

Inhaled nitric oxide improves hemodynamics in patients with acute pulmonary hypertension after high-risk cardiac surgery.

Severe pulmonary hypertension and right-sided circulatory failure (RSCF) represent an increasing cause of morbidity and mortality in patients undergoing high-risk cardiac surgery. Increased pulmonary vascular resistance in the setting of cardiopulmonary bypass (CPB) may further lead to decreased blood flow across the pulmonary vascular bed; thereby decreasing left ventricular filling and cardiac output. Current management techniques for RSCF include both nonspecific vasodilator and inotropic agents (often limited by systemic hypotension) and the placement of right ventricular assist devices (associated with increased perioperative morbidity). Inhaled nitric oxide (NOi) represents a novel, specific pulmonary vasodilator that has been proven efficacious in these clinical settings. We evaluated 34 patients in 38 operations who underwent cardiac surgery at Columbia Presbyterian Medical Center, and who received NOi (20 ppm) through a modified ventilatory circuit for hemodynamically significant elevations in pulmonary vascular resistance. Nine patients underwent cardiac transplantation, three patients bilateral lung transplantation, 16 patients left ventricular assist device placement and 10 patients routine cardiac surgery. Patients receiving NOi exhibited substantial reductions in mean pulmonary artery pressure (mPAP) (34.6 ± 2.0 to 26.0 ± 1.7 mmHg, p < 0.0001), with improvements in systemic hemodynamics, mean arterial pressure (68 ± 3.1 to 75.9 ± 2.0 mmHg, p = 0.006). In five cases, patients could not be weaned from CPB until NOi was administered. Patients were maintained on NOi from 6 to 240 h postoperatively (median duration 36 h). Inhaled NO induces substantial reductions in mPAP and increases in both cardiac index and systemic blood pressure in patients displaying elevated pulmonary hemodynamics after high-risk cardiac surgery. NO is, therefore, a useful adjunct in these patients in whom acute pulmonary hypertension threatens right ventricular function and hemodynamic stability.

Endotoxin in pooled pericardial blood contributes to the systemic inflammatory response during cardiac surgery

Although endotoxin has been implicated as an important contributor to the systemic inflammatory response (SIR) during cardiopulmonary bypass (CPB), its source remains unclear. While gut translocation has traditionally been perceived as the primary source of endotoxemia, accumulation of endotoxin in pooled pericardial blood may represent an additional source of endotoxin that is continually reinfused into the CPB circuit. Eighteen patients undergoing primary coronary revascularization procedures were prospectively evaluated. Shed blood pooled in the pericardial space was returned to the CPB circuit through cardiotomy suction catheters at 45 min after placement of the aortic crossclamp. Simultaneous samples of pooled pericardial and peripheral arterial blood were obtained and analyzed by a limulus amebocyte lysate assay for the determination of endotoxin concentration, and an enzyme-linked immonosorbert assay for tumor necrosis factor (TNF-α) levels. Significant elevations in endotoxin were demonstrated in pooled pericardial blood samples compared with arterial blood (3.5 ± 0.5 vs 0.8 ± 0.2 pg/ml; p < 0.05). TNF-α levels were below the limits of detection in both samples. These data implicate pooled pericardial blood as an important primary source of endotoxin that, when continually reinfused throughout CPB, may contribute to the overall SIR. Because endotoxemia has been identified as an important predictor of adverse outcomes following cardiac surgery, removal of endotoxin antigen in shed pericardial blood, prior to its reinfusion into the CPB circuit, may provide a directed means to improve perioperative outcome without compromising established blood conservation techniques.

Preserved gastric tonometric variables in cardiac surgical patients administered intravenous perflubron emulsion.

Low gastric intramucosal pH (pHi) and an increased gastric-arterial Pco2 difference (CO2 gap) are markers of tissue hypoperfusion. Perfluorocarbons (PFCs) have a large oxygen-carrying capacity and release oxygen when encountering low tissue oxygen tension. Nine cardiac surgical patients instrumented for gastric tonometry were enrolled as part of a multicenter, randomized, single-blinded study of a PFC emulsion (perflubron emulsion [Oxygent™]). Patients were randomized to receive PFC (n = 4) or placebo (n = 5) after intraoperative autologous blood harvesting by acute normovolemic hemodilution. At baseline there were no intergroup differences in tonometric-, hemodynamic-, or oxygen delivery-derived variables, e.g., Control group (pHi, 7.37 ± 0.06; CO2 gap, 6.4 ± 1.3 mm Hg) versus PFC group (pHi, 7.38 ± 0.06; CO2 gap, 6.7 ± 1.5 mm Hg). After acute normovolemic hemodilution, pHi was significantly lower (P < 0.01) in the Control group (7.22 ± 0.25) than in the PFC group (7.44 ± 0.25), and CO2 gap was significantly higher (P < 0.001) in the Control group (23.4 ± 5.1 mm Hg) than in the PFC group (1.8 ± 0.8 mm Hg). These differences in tonometric variables persisted during surgery. The PFC group showed a significantly (P < 0.007) shorter time to first bowel movement postoperatively (2.0 ± 0.8 vs 5.4 ± 1.6 days). Time to consumption of solid food was also shorter in the PFC group and almost achieved statistical significance (P = 0.056).

180 ml and less: cardiopulmonary bypass techniques to minimize hemodilution for neonates and small infants.

Objective . To determine the efficacy of decreasing cardiopulmonary bypass (CPB) prime volume for neonates and small infants by using low prime oxygenators, small diameter polyvinyl chloride (PVC) tubing and removing the arterial line filter (ALF) in an effort to reduce intraoperative exposure to multiple units of packed red blood cells (PRBC). Methods. Two retrospective database studies comparing neonatal CPB prime volume were undertaken: Study 1 — A CPB circuit consisting of a 1/8 inch arterial line, a 3/16 inch venous line and a low prime oxygenator with 172 ml total circuit prime (n = 74) was compared to a circuit with a 3/16 inch arterial line, a 1/4 inch venous line and a higher prime oxygenator with a 350 ml total circuit prime ( n = 74). Study 2 — The 172 ml circuit (n = 389) was compared to a circuit that included an ALF and had a total circuit prime volume of 218 ml (n = 389). Results. Study 1— of the 74 neonates and small infants whose CPB prime volume was 350 ml, 19 were exposed to two or more intraoperative exogenous PRBC units while only 3 neonates and small infants in the 172 ml prime group (n = 74) received two or more units (p = 0.0002). Study 2 — of the 389 neonates and small infants where an ALF was used (prime volume 218 ml), 54 were exposed to two or more exogenous PRBC units while only 36 of the 389 patients where an ALF was not used (prime volume 172 ml) received two or more units of intraoperative PRBCs (p = 0.0436). Conclusion. Decreasing the neonatal and small infant extracorporeal circuit prime volume by as little as 46 ml resulted in significantly fewer multiple exposures to exogenous PRBC units. Perfusion (2007) 22, 327—331.

Electrocardiographic Artifacts During Cardiopulmonary Bypass

An electrocardiogram (ECG) free from interference is today a necessity for safe anesthetic management. Electrocardiogram artifacts caused by surgical cautery units, power lines, and muscle twitching and fasciculation have been recognized (14). More recently, ECG interference has been observed during extracorporeal shock wave lithotripsy (5) and during crystalloid administration through a fluid warming apparatus (6). During cardiopulmonary bypass (CPB) we have been experiencing another type of ECG artifact, which has not yet been reported. The purpose of this paper is to describe the characteristics and incidence of this interference, and to suggest an etiology and possibly a solution to the problem.