Toru Matayoshi

Intraoperative assessment of coronary artery bypass graft: transit-time flowmetry versus angiography.

BACKGROUND Transit-time flowmetry has been used to assess graft status intraoperatively. This study examines the validity of this method by comparing its results with the findings of simultaneously performed graft angiography. METHODS The left internal thoracic artery (LITA) anastomosed to the left anterior descending artery (LAD) was assessed intraoperatively with both transit-time flowmetry and graft angiography in 30 patients. The patients were stratified into two groups based on intraoperative angiographic findings. In 18 patients (group A), the LITA and the LAD were well filled with contrast medium and the anastomosis was widely patent. In the other 12 patients (group B), spastic LITA or LAD was observed. Postoperative angiography was also performed before discharge from the hospital. RESULTS The mean graft flow was 44.0 +/- 25.4 mL/min in group A and 23.4 +/- 10.0 mL/min in group B (p = 0.0129). Diastolic-dominant flow pattern was observed in both groups, and the ratio of peak diastolic flow to peak systolic flow and the percent diastolic time-flow integral were not statistically different between the groups. The pulsatility index was almost the same between the two groups and was acceptable in both. Postoperative angiography revealed that all grafts were patent without spasm or anastomotic stenosis. CONCLUSIONS LITA graft status is satisfactory when high graft flow with diastolic dominance is obtained. When there is vasospasm but no anastomotic problems, decreased graft flow with an acceptable pulsatility index and diastolic augmentation is observed.

Effects of atrial fibrillation on coronary artery bypass graft flow

OBJECTIVES No detailed studies exist of coronary artery bypass graft flow during atrial fibrillation. We examined the effects on bypass graft flow of atrial fibrillation following coronary artery bypass grafting. METHODS Immediately after surgical revisualization, atrial fibrillation was induced in 18 patients by high frequency atrial pacing. Hemodynamic variables were measured in sinus rhythm and atrial fibrillation. The graft flow in pedicled left internal thoracic artery grafts and in saphenous vein grafts was also measured using transit-time flowmetry. RESULTS Left internal thoracic artery graft flow had a greater diastolic component than saphenous vein graft flow, as shown by the percent diastolic time-flow integral (86 +/- 10% in the left thoracic artery and 62 +/- 12% in the saphenous vein, P < 0.0001). The induced atrial fibrillation caused significant deterioration in hemodynamics: heart rate and central venous pressure increased, and mean arterial pressure and cardiac index decreased (all P < 0.0025). In left internal thoracic artery grafts (n = 18) and also in saphenous vein grafts (n = 20), graft flow decreased significantly with atrial fibrillation (44.3 +/- 26.2 to 26.2 +/- 20.7 ml/min in the left internal thoracic artery, P = 0.0003; 39.7 +/- 15.6 to 33.3 +/- 14.3 ml/min in the saphenous vein, P = 0.001). The reduction in graft flow due to atrial fibrillation was much larger in left internal thoracic artery grafts than in saphenous vein grafts (P = 0.0008). CONCLUSIONS Direct measurement of coronary artery bypass graft flow shows that atrial fibrillation after surgery significantly reduces graft flow. The effect is much larger in left internal thoracic artery grafts with their strong diastolic component than in saphenous vein grafts.

Total Arch Replacement Under Flow Monitoring During Selective Cerebral Perfusion Using a Single Pump

BACKGROUND Flow in individual vessels is passively determined when a single pump is used for selective cerebral perfusion during aortic arch surgery. We installed a Doppler flowmeter in the circuit and measured flow in the supraaortic vessels to determine flow distribution during selective cerebral perfusion. METHODS We cannulated and perfused three supraaortic vessels using a single pump in 203 patients who underwent elective (n = 158) or emergency or urgent (n = 45) total arch replacement using a four-branched prosthetic graft. Flow rates in each branch were continuously monitored during selective cerebral perfusion. RESULTS The respective mean flow rates in the brachiocephalic, left common carotid, and left subclavian arteries and total flow rates were 5.8, 3.3, 3.4, and 12.5 mL·kg(-1)·min(-1). The ratios of flow in these vessels to total flow were 46.5%, 26.5%, and 27.0%, respectively, and they were not affected by the total flow rate. In-hospital mortality rates among the patients who underwent elective and emergency or urgent surgery were 1.9% (n = 3) and 11.1% (n = 5), respectively, and the rates of postoperative stroke were 2.5% (n = 4) and 8.9% (n = 4), respectively. Total flow in the supraaortic vessels during selective cerebral perfusion was significantly lower in patients with neurologic complications than in those without (732 versus 806 mL/min; p = 0.034). CONCLUSIONS Flow monitoring showed that selective perfusion using a single pump adequately distributed flow among all supraaortic vessels. This monitoring system might help to improve brain protection and outcomes during total aortic arch replacement.

Efficiency of an air filter at the drainage site in a closed circuit with a centrifugal blood pump: An in vitro study

In a closed circuit with a centrifugal blood pump, one of the serious obstacles to clinical application is sucking of air bubbles into the drainage circuit. The goal of this study was to investigate the efficiency of an air filter at the drainage site. We used whole bovine blood and the experimental circuit consisted of a drainage circuit, two air filters, a centrifugal blood pump, a membrane oxygenator, a return circuit, and a reservoir. Air was injected into the drainage circuit with a roller pump, and the number and size of air bubbles were measured. The air filter at the drainage site could remove the air bubbles (>40 &mgr;m) by itself, but adding a vacuum removed more bubbles (>40 &mgr;m) than without vacuum. Our results suggest that an air filter at the drainage site could effectively remove air bubbles, and that adding the filter in a closed circuit with a centrifugal blood pump would be safer.

Quantitative evaluation of hand cranking a roller pump in a crisis management drill

The heart-lung machines for open-heart surgery have improved over the past 50 years; they rarely break down and are almost always equipped with backup batteries. The hand-cranking procedure only becomes necessary when a pump breaks down during perfusion or after the batteries have run out. In this study, the performance of hand cranking a roller pump was quantitatively assessed by an objective method using the ECCSIM-Lite educational simulator system. A roller pump connected to an extracorporeal circuit with an oxygenator and with gravity venous drainage was used. A flow sensor unit consisting of electromagnetic sensors was used to measure arterial and venous flow rates, and a built-in pressure sensor was used to measure the water level in the reservoir. A preliminary study of continuous cranking by a team of six people was conducted as a surprise drill. This system was then used at a perfusion seminar. At the seminar, 1-min hand-cranking drills were conducted by volunteers according to a prepared scenario. The data were calculated on site and trend graphs of individual performances were given to the participants as a handout. Preliminary studies showed that each person’s performance was different. Results from 1-min drills showed that good performance was not related to the number of clinical cases experienced, years of practice, or experience in hand cranking. Hand cranking to maintain the target flow rate could be achieved without practice; however, manipulating the venous return clamp requires practice. While the necessity of performing hand cranking during perfusion due to pump failure is rare, we believe that it is beneficial for perfusionists and patients to include hand-cranking practice in periodic extracorporeal circulation crisis management drills because a drill allows perfusionists to mentally rehearse the procedures should such a crisis occur.

A new endo aortic occlusion balloon for limited access cardiac surgery: development and clinical evaluation.

In recent years, minimally invasive cardiac surgery (MICS), or limited access cardiac surgery, has been presented as a promising operative procedure. We developed a new balloon device that is inserted directly into the ascending aorta to stop the heart during limited access cardiac surgery. The balloon has a three lumen structure: balloon lumen port, cardioplegia/vent lumen port, and aortic root lumen port. This direct EAC balloon catheter, designed to be inserted directly into the ascending aorta, is different from the Heartport system. The Heartport EAC balloon catheter is inserted into the aorta via an artery in the lower limb, making lower limb arterial disease a key concern. Our Direct Endo Aortic Clamp (EAC) balloon overcomes this problem. The device was clinically used in seven cardiac cases. All patients were discharged within 5 postoperative days, confirming the utility of the device.

Extracorporeal circulation technical training DVD volume 1: basic operation and troubleshooting scenarios

The Committee of Education of the Japanese Society for Artifi cial Organs believes that the teaching of safety with respect to extracorporeal circulation technique is important. Consequently, a DVD titled “Measures to Resolve Incidents During Extracorporeal Circulation” (Fig. 1) was produced. It is the fi rst educational DVD on extracorporeal circulation (ECC) produced in Japan by the Japanese Society for Artifi cial Organs with cooperation from The Japanese Society of Extra-Corporeal Technology in Medicine (JaSECT). The production aimed at ensuring and improving safety during ECC. In this DVD, the maneuvers employed in crisis management drills are presented with narration and dialogue in Japanese. The learning objective was to promote appropriate action for specifi c situations when a problem related to ECC occurs. Additionally, the usefulness of safety devices, the proper location for pressure measurement, the locations for fi xing sensors, and other technical aspects are presented. This DVD helps perfusionists to confi rm the installation of safety devices and the location where the pressure of the oxygenator can be appropriately measured. When there is more than one solution to a problem, ideally such a DVD should cover all possible approaches to problem solving. However, we have chosen several incidents and only one solution for each is shown; the reason for this is that choices of solution change by the situation. This DVD was produced based on the information available in Japan concerning safety measures of extracorporeal technology in 2006, and we believe that this information is still applicable at the current time. An English translation of the DVD scenarios is given below with the authors’ comJ Artif Organs (2009) 12:278–282

Speed-controlled venovenous modified ultrafiltration for pediatric open heart operations

Although modified ultrafiltration after pediatric open heart operations is used by several clinical centers, the risk of complications is a matter of concern. This report describes a simple, reliable, and reproducible technique of speed-controlled venovenous modified ultrafiltration.

Open anastomosis of extracardiac conduit for total cavopulmonary connection decreases post-operative pleural effusion.

OBJECTIVE The goal of this study was to see whether the open anastomosis technique using vacuum-assisted venous drainage at the time of the Fontan procedure was associated with decreased post-operative pleural effusion. METHODS We analysed a subgroup of patients with a functional single ventricle who underwent non-fenestrated total cavopulmonary connection completion with the insertion of an extracardiac conduit as the sole or predominant procedure conducted by a single surgeon at a single institute, using either an open or closed anastomosis technique. RESULTS Median age and weight were 2.3 years, with a range from 1.3 to 27.6 years and 11.4 kilograms, with a range from 9.7 to 43 kilograms, respectively. The open anastomosis technique was associated with a shorter bypass run (p = 0.015), decreased surgical duration (p = 0.032), fewer pleural effusion days (p = 0.049), and lesser pleural effusion (p = 0.013) than closed anastomosis. Correlation analysis demonstrated a significant relationship between the amount of pleural effusion and surgical duration (correlation efficient, 0.535; p = 0.033). A logistic regression model showed that the open technique was associated with a 20-fold increase in the likelihood of having a total chest tube discharge of less than 300 millilitres (p = 0.027). CONCLUSIONS The open anastomosis technique shortens operative duration and bypass run, which in turn might contribute to decreased pleural effusion soon after the modified Fontan procedure.

Comparison of active and passive coronary perfusion in off-pump coronary artery bypass grafting

The myocardial protective effects of active and passive coronary perfusion were compared during off-pump coronary artery bypass grafting (OPCAB) in coronary stenosis model. An internal shunt tube was placed in the proximal left anterior descending arteries of adult dogs to produce a 75% coronary stenosis model. In 10 animals passive coronary perfusion was performed using an internal shunt tube placed in a pseudo-anastomotic site, and active coronary perfusion was performed through an external shunt tube. Ischemia was examined at normal and low blood pressure, based on hemodynamics, regional myocardial blood flow, and oxygen and lactate extraction in the perfused area. With passive perfusion, regional myocardial blood flow decreased and oxygen extraction and regional lactate production increased at normal blood pressure, indicating myocardial ischemia. Regional myocardial blood flow further decreased at low blood pressure. In contrast, regional myocardial blood flow with active perfusion did not change at normal or low blood pressure, and oxygen and lactate extraction were unchanged, indicating prevention of myocardial ischemia. Myocardial ischemia can occur with passive perfusion even at normal blood pressure. Active coronary perfusion that provides sufficient regional perfusion prevents myocardial ischemia during coronary artery anastomosis in OPCAB.