Aortic Cannula Research Articles

An in vitro fluid dynamic study of pediatric cannulae: the value of animal studies to predict human flow.

A challenge to the development of pediatric ventricular assist devices (PVADs) is the use of the aortic cannulae attached to the devices. Cannulae used for pediatric application have small diameters and large pressure drops. Furthermore, during the development of the 12cc Penn State pediatric PVAD, particle image velocimetry (PIV) illustrated that hematocrit levels, through changes in blood viscoelasticity, affected the fluid dynamics. The objective of this study is to compare the fluid dynamics of a pediatric viscoelastic blood analog and a goat viscoelastic blood analog within the PVAD aortic cannula. Two acrylic models were manufactured to model the aortic cannula (6 mm and 8 mm diameters). PIV data was collected to examine the flow at the outlet of the VAD and in the aortic cannula at heart rates of 50 and 75 beats per minute (bpm). Three planes of data were taken, one at the centerline and two 1.5 mm above and below the centerline. Three more planes of data were taken orthogonal to the original planes. While a 75 bpm heart rate was used to represent normal operating conditions, a 50 bpm heart rate represented use of the PVAD during weaning. At 75 bpm, differences were evident between the two different fluids and the two models. Separation zones developed in the plane below the centerline for the higher hematocrit pediatric blood analog. This study raises question to the usefulness of animal testing results in regard to how well they predict the outcome of pediatric patients.

Thoracoabdominal aortic aneurysm repair using hypothermic cardiopulmonary bypass and circulatory arrest.

Thoracoabdominal aortic aneurysm repair using hypothermic cardiopulmonary bypass and circulatory arrest.

Surgical Experience of Ascending Aorta and Aortic Valve Replacement in Patient with Calcified Aorta

BackgroundThe conventional method of aortic cross-clamping is very difficult and increases the risk of cerebral infarct due to embolism of the calcified aorta in these patients. Accordingly, we analyzed our experience with 11 cases of ascending aorta and aortic valve replacement with hypothermic circulatory arrest.Materials and MethodsFrom January 2002 to December 2009, 11 patients had ascending aorta and aortic valve replacement with hypothermic arrest at our hospital. We performed a retrospective study.ResultsThere were 5 males and 6 females, with a mean age of 68 years (range, 44 to 82 years). Eight patients had aortic stenosis, and 3 patients had aortic regurgitation. An aortic cannula was inserted into the right axillary artery in 3 patients and ascending aorta in 6 patients. Two patients with aortic regurgitation had a remote access perfusion catheter inserted though the right femoral artery. The mean cardiopulmonary bypass time was 180 minutes (range, 110 to 306 minutes) and mean hypothermic circulatory arrest time was 30 minutes (range, 20 to 48 minutes). The mean rectal temperature during hypothermic circulatory arrest was 21℃ (range, 19℃ to 23℃). No patient had any new onset of cerebral infarct or cardiovascular accident after surgery. There was no hospital mortality. Early complications occurred in 1 patient who needed reoperation due to postoperative bleeding. Late complications occurred in 1 patient who underwent a Bentall operation due to prosthetic valve endocarditis. The mean follow-up duration was 32 months (range, 1 month to 8 years) and 1 patient died suddenly due to unknown causes after 5 years.ConclusionPatients with a calcified aorta can be safely treated with a technique based on aorta and aortic valve replacement under hypothermic circulatory arrest.

A102 Side-hole type送血カニューレの流動特性解析と臨床評価による妥当性の検討(A1-1 生体流体工学1)

A102 Side-hole type送血カニューレの流動特性解析と臨床評価による妥当性の検討(A1-1 生体流体工学1)

The influence and function mechanism of hyperbaric oxygen pretreatment on myocardial ischemia reperfusion injury in rats

Background and objectiveIn recent years, coronary atherosclerotic heart disease become the major disease which is harmful to human health with a rising the trend of incidence. The world health organisation...

Successful Use of Hirudin During Cardiac Surgery Using Minimized Extracorporeal Circulation in Patients With Heparin-Induced Thrombocytopenia

In this case series, we describe our successful use of a reduced hirudin dosage as an anticoagulant during cardiac surgery using minimized extracorporeal circulation in patients with heparin-induced thrombocytopenia.

Minimally invasive aortic valve replacement via right anterior minithoracotomy: Early outcomes and midterm follow-up

FIGURE 1. A, Axial plane shows the right position of the aorta with respect t feasibility of cannulating the ascending aorta and replacing the aortic valve throu ment. AC, Aortic cannula; AT, aortic tourniquet; XC, crossclamp; LVV, left ven From the Department of Cardiothoracic Surgery, Fondazione G. Monasterio, CNR—Regione Toscana, Massa, Italy. Disclosures: Authors have nothing to disclose with regard to commercial support. Received for publication Jan 28, 2011; revisions received April 26, 2011; accepted for publication May 17, 2011; available ahead of print July 4, 2011. Address for reprints: Antonio Miceli, MD, Fondazione G. Monasterio, CNR-regione Toscana, 54100 Massa, Italy (E-mail: antoniomiceli79@alice.it). J Thorac Cardiovasc Surg 2011;142:1577-9 0022-5223/$36.00 Copyright 2011 by The American Association for Thoracic Surgery doi:10.1016/j.jtcvs.2011.05.011

Epi-aortic ultrasound for cannulating the true lumen of a thoracic dissection — A case report

The application of epi-aortic ultrasound to identify and cannulate the true lumen of a dissecting descending thoracic aneurysm for which left atrial–femoral partial bypass was required is described. Because of scarring and inflammation, cannulation of the femoral artery could not be accomplished. For placement of the cannula in the descending aorta, we used an epi-aortic probe to identify the true lumen of the dissection and to direct the guidewire appropriately. The aortic cannula was passed over the wire and its position was also confirmed by ultrasound. Left atrial to descending aorta bypass was initiated without complications.

Numerical simulation of hemodynamics in the ascending aorta induced by different aortic cannulas

There is still a lack of quantitative information concerning optimal blood flow in the aorta and in the carotid arteries during extracorporeal circulation (ECC). Problems are not only based on the location of the aortic cannula, they are furthermore associated with the cannula design itself and the effects on blood cells and aortic wall shear stresses. We simulated a two-phase fluid flow induced by different cannulas in the ascending aorta during ECC. Three commercially available cannulas were examined according to their influence on red blood cells (RBC). Additionally, mass flow in the carotid vessels and wall shear stresses acting on the aortic wall were evaluated. A constant volume flow of blood (3.4 L/min) was applied. Numerical results demonstrate a strong relation between the mass flow rate in the carotid vessels and the geometry of the aortic outflow cannula. RBC distributions both in the aorta and the carotid vessels changed depending on cannula geometry. Maximum blood velocities, shear stresses on the aortic wall, and the fluid mechanical load acting on RBCs varied depending on each cannula design. This numerical approach demonstrates the significant influence of the cannula design on the distribution of RBCs in the carotid vessels during ECC.

Cannulation of the innominate artery for surgery of acute thoracic aortic aneurysm (surgical movie)

We present a new simplified technique for arterial cannulation of the innominate artery for extracorporal circulation in thoracic aneurysms. Access is gained via a minor enlargement of a standart median sternotomie. First, with the pericardium still closed, incision of the innominate artery superior to the innominate vein is performed. After heparin is given a 20–22 French straight aortic cannula is inserted and the flow directed to the aortic arch. Later for inspection or replacement of the arch the cannula is again turned by 180 degrees and the flow reduced to 1–1.5l/min at 28°C while the artery is clamped and the arch opened. For reperfusion the same cannula is left in place and again turned by 180 degrees in order to achieve a direct antegrade flow.

Implanted CardioWest-t total artificial heart: three-dimensional computed tomography reconstruction

Fig. 1. Post-implantation 3D computed tomography (CT) scan (multidetector CT dual source — 64 slices, Siemens, Erlangen, Germany) reconstruction of the CardioWest-t total artificial heart (TAH) showing the satisfactory position of the device in the chest of the patient (Video 1) (patient consensus was obtained). The left artificial ventricle is connected via the left atrial inflow connector to the left atrium, and via the aortic outflow cannula to the aorta. The right artificial ventricle is connected via the right atrial inflow connector to the right atrium and via the pulmonary artery outflow cannula to the pulmonary artery. The two driveline conduits are tunneled through the chest wall. After rethoracotomy for bleeding of the patient, the 3D CT scan evaluation showed no blood leak or torsion and kinking of both atria and great vessels, and the satisfactory position of the device components as well. § This report was carried out within the PhD Program in ‘Transplantation’ awarded by Rome Tor Vergata University, Italy, in cooperation with the Deutsches Herzzentrum Berlin, Germany. * Corresponding author. Address: Department of Cardiac Surgery and Transplantation, S. Camillo Hospital, P.za C. Forlanini n.1, 00151 Rome, Italy. Tel.: +39 06 5870 4401; fax: +39 06 5870 4706. E-mail address: antonioloforte@yahoo.it (A. Loforte).

Transaortic Endoclamp for Mitral Valve Operation through Right Minithoracotomy in 369 Patients

: The effects and benefits of a transaortic endoclamp for mitral valve operation through right minithoracotomy have not been established. : The records were examined in 671 patients undergoing mitral valve operation using aortic cannulation through a 6-cm right minithoracotomy in the fourth intercostal space. The ascending aorta was cannulated with a 24-Fr cannula through a 12-mm port in the first intercostal space. The experience from 1998 to 2006 with aortic endoclamping (group A, N = 436) was compared with the experience from 2006 to 2009 with external aortic clamping (group B, N = 235). Aortic endoclamping was achieved with a 30 mL endoclamp introduced through the aortic cannula into the ascending aorta to provide aortic endoclamping, anterograde cardioplegia, and root venting. Percutaneous femoral venous cannulation was used. : Group A and group B had similar demographics. Endoclamp availability (group A) resulted in significantly less fibrillatory arrest (no clamping) in 67 of 436 (15%) versus 104 of 235 (44%) patients in group B (P = 0.001). In patients with aortic clamping, endoclamp (group A) versus external clamp (group B) was not a determinant of clamp time or pump time. Hospital and late outcomes were not different between groups. No patient complications could be attributed to the endoclamp. : Aortic endoclamping requires no more clamp or pump time than external clamping and can provide a more bloodless field than ventricular fibrillation without obstructing hardware. Aortic endoclamping is a safe alternative for mitral surgery through right minithoracotomy.

Transaortic endoclamp for mitral valve operation through right minithoracotomy in 369 patients.

: The effects and benefits of a transaortic endoclamp for mitral valve operation through right minithoracotomy have not been established. : The records were examined in 671 patients undergoing mitral valve operation using aortic cannulation through a 6-cm right minithoracotomy in the fourth intercostal space. The ascending aorta was cannulated with a 24-Fr cannula through a 12-mm port in the first intercostal space. The experience from 1998 to 2006 with aortic endoclamping (group A, N = 436) was compared with the experience from 2006 to 2009 with external aortic clamping (group B, N = 235). Aortic endoclamping was achieved with a 30 mL endoclamp introduced through the aortic cannula into the ascending aorta to provide aortic endoclamping, anterograde cardioplegia, and root venting. Percutaneous femoral venous cannulation was used. : Group A and group B had similar demographics. Endoclamp availability (group A) resulted in significantly less fibrillatory arrest (no clamping) in 67 of 436 (15%) versus 104 of 235 (44%) patients in group B (P = 0.001). In patients with aortic clamping, endoclamp (group A) versus external clamp (group B) was not a determinant of clamp time or pump time. Hospital and late outcomes were not different between groups. No patient complications could be attributed to the endoclamp. : Aortic endoclamping requires no more clamp or pump time than external clamping and can provide a more bloodless field than ventricular fibrillation without obstructing hardware. Aortic endoclamping is a safe alternative for mitral surgery through right minithoracotomy.

Measurement of Hemodynamic Energy at Different Vessels in an Adult Swine Model

Extra hemodynamic energy is one of the major benefits of pulsatile flow, improving blood flow to vital organs. But most (80%) of the hemodynamic energy generated from pulsatile flow is damped by the extracorporeal circuit. Most models devised to minimize hemodynamic energy loss have been in vitro pediatric models. The purpose of this study was to measure hemodynamic energy in different vessels of different organs with an in vivo adult swine model. An extracorporeal circuit was constructed for seven Yorkshire swine using a pulsatile pump (Twin-Pulse Life Support). The mean arterial pressure (MAP), energy equivalent pressure (EEP), and surplus hemodynamic energy (SHE) at the renal artery, carotid artery, aortic cannula site, and postoxygenator site were measured simultaneously before starting the pump and at the pump rates of 25, 35, and 45 bpm. The MAP of the renal or carotid artery was 40.0%-51.2% of the postoxygenator site. The EEP and SHE of both arteries were 11.6%-13.0% and 5.5%-7.4% of the postoxygenator site, respectively. The MAP and EEP of both arteries after starting the pump were lower than at baseline. The SHE of the renal artery after starting the pump was significantly higher than at baseline. The SHE of the carotid artery increased substantially after starting the pump although not statistically significantly. There was a significant hemodynamic energy loss in both arterial sites compared with the postoxygenator site. Also, a difference in hemodynamic energy loss was observed in vessel-to-vessel or vessel-to-circuit site comparison. This difference creates a bias in studying pulsatility and its effects. Therefore, the measurement method of hemodynamic energy must be standardized and the measurement site clarified to yield accurate study results.

Avoiding Stroke During Cardiac Surgery

The life saving benefits of cardiac surgery are frequently accompanied by negative side effects such as stroke, that occurs with an incidence of 2%-13% dependent to type of surgery. The etiology is most likely multifactorial with embolic events considered as main contributor. Although stroke presents a common complication, no guidelines for any routine use of pharmacological substances or non-pharmacological strategies exist to date. Non-pharmacological strategies include monitoring of brain oxygenation and perfusion with devices such as near infrared spectroscopy and Transcranial Doppler help. Epiaortic and transesophageal echocardiography visualize aorta pathology, enabling the surgeon to sidestep atheromatous segments. Additionally can the use of specially designed aortic cannulae and filters help to reduce embolization. Brain perfusion can be improved by using antero- or retrograde cerebral perfusion during deep hypothermic circulatory arrest, by tightly monitoring mean arterial blood pressure and hemodilution. Controlling perioperative temperature and glucose levels may additionally help to ameliorate secondary damage. Many pharmacological compounds have been shown to be neuroprotective in preclinical models, but clinical studies failed to confirm these results so far. Remacemide, an NMDA-receptor-antagonist showed a significant drug-based neuroprotection during cardiac surgery. Other substances currently assessed in clinical trials whose results are still pending are acadesine, an adenosine-regulating substance, the free radical scavenger edaravone and the local anesthetic lidocaine. Stroke remains as significant complication after cardiac surgery. Non-pharmacological strategies allow perioperative caregivers to detect injurious events and to ameliorate stroke and its sequelae. Considering the multi-factorial etiology though, stroke prevention will likely have to be addressed with an individualistic combination of different strategies and substances.

Experimental Fluid Dynamics of Transventricular Apical Aortic Cannulation

To clarify the flow pattern from a transventricular apical aortic cannula, hydrodynamic analysis of transventricular apical aortic cannulation (apical cannulation) was performed using particle-image velocimetry in a glass aortic model. Simulated apical cannulation using a 7-mm Sarns Soft-Flow cannula and the newly developed 7-mm apical aortic cannula was compared with standard aortic cannulation. The flow-velocity, streamline, and distribution of magnitude of the strain rate tensor (function of shear stress) were analyzed. Streamline analysis revealed a steady and organized flow profile in apical cannulation as compared with that in standard aortic cannulation. The magnitude of the strain rate tensor decreased within a few centimeters from the exit of the apical cannula.

A multicenter randomized controlled trial to assess the feasibility of testing modified ultrafiltration as a blood conservation technology in cardiac surgery

Modified ultrafiltration is a technique after cardiopulmonary bypass whereby blood withdrawn from the aortic cannula is passed across a semipermeable membrane to hemoconcentrate. Unblinded trials have suggested that modified ultrafiltration is efficacious for blood conservation. The objective of this trial was to assess the feasibility of a model testing modified ultrafiltration in which all members of the surgical team were blinded to the intervention. Patients (<65kg) undergoing procedures involving cardiopulmonary bypass were randomized to undergo either modified ultrafiltration (n=29) or sham (circulation without an interposed filter, n=36) for 15minutes. The circuit was shielded from all members of the team except the perfusionist. A questionnaire was administered to determine the blinding success. Modified ultrafiltration resulted in a removal of 1000+/-251mL of fluid and a reduction in the pump balance (1025+/-807 vs 1804+/-838; P < .001) with an increase in hemoglobin immediately after intervention (increase of 7.7+/-8.8g/L in modified ultrafiltration vs 3.8+/-5.1g/L in sham; P=.04). Introduction or increase in dose of vasopressors was more frequent in the modified ultrafiltration group (52% vs 28%; P=.048). Differences in red cell transfusion rates between groups did not reach statistical significance (P=.59). Blinding was successful for the anesthetist (blinding index 0.13 [95% confidence interval, 0.11-0.38] and the intensivist (blinding index, 0.09 [95% confidence interval, 0.14-0.31]) but not for the surgeon (blinding index, 0.24 [95% confidence interval, 0.05-0.42]). The compliance rate for the transfusion protocol was greater than 90%. Modified ultrafiltration was effective for hemoconcentration after cardiopulmonary bypass in patients of low body weight, but it is associated with an increased need for vasopressor support. The anesthetist and intensivist were successfully blinded to the intervention.

An Aortic Cinch to Quell Suture Line Bleeding

Bleeding from an aortic suture line or cannula site may be difficult to control, especially in the patient with a fragile or dilated aorta. This method of wrapping a vascular graft around the aorta to relieve tension on the suture line and control bleeding is simple and effective, and it facilitates obtaining the proper tension of the wrapped graft.

Hydrodynamics of Aortic Cannulae During Extracorporeal Circulation in a Mock Aortic Arch Aneurysm Model

This study was designed to analyze flow pattern, velocity, and strain on the aortic wall of a glass aortic arch aneurysm model during the extracorporeal circulation, and to elucidate the characteristics of flow pattern in three different aortic cannulae. Different patterns of large vortices and helical flow were made by each cannula. With the curved end-hole cannula, the high velocity flow (approximately 0.6-0.8 m/s) was blowing to the aneurismal wall without attenuating the strain rate tensor (approximately 0.2-0.25/s). With the dispersion cannula and the Soft-Flow cannula, cannular jet was attenuated in the ascending aorta creating a large vortex at a velocity less than 0.5 m/s, and the strain rate tensor on the aneurismal wall was small (less than 0.15/s). In conclusion, end-hole cannula should not be used in the operation of aortic arch aneurysm. Dispersion-type aortic cannulae were less invasive on the aortic arch aneurismal wall, but particular attention to alternative cannulation sites should be paid in cases with severe atherosclerosis on the ascending aortic wall.

Development of Arterial Blood Supply in Experimental Liver Metastases

In this study, we present a mechanism for the development of arterial blood supply in experimental liver metastases. To analyze the arterialization process of experimental liver metastases, we elucidated a few key questions regarding the blood supply of hepatic lobules in mice. The microvasculature of the mouse liver is characterized by numerous arterioportal anastomoses and arterial terminations at the base of the lobules. These terminations supply one hepatic microcirculatory subunit per lobule, which we call an arterial hepatic microcirculatory subunit (aHMS). The process of arterialization can be divided into the following steps: 1) distortion of the aHMS by metastasis; 2) initial fusion of the sinusoids of the aHMS at the tumor parenchyma interface; 3) fusion of the sinusoids located at the base of the aHMSs, which leads to the disruption of the vascular sphincter (burst pipe); 4) incorporation of the dilated artery and the fused sinusoids into the tumor; and 5) further development of the tumor vasculature (arterial tree) by proliferation, remodeling, and continuous incorporation of fused sinusoids at the tumor-parenchyma interface. This process leads to the inevitable arterialization of liver metastases above the 2000- to 2500-mum size, regardless of the origin and growth pattern of the tumor.