Yoshie Ochiai

Comparative study of retrograde and selective cerebral perfusion with transcranial Doppler

BACKGROUND Retrograde cerebral perfusion (RCP) is a simple technique and is expected to provide cerebral protection. However, its optimum management and limitations remain unclear. Transcranial Doppler has been used to monitor cerebral perfusion. Using this Doppler technique, we compared cerebral blood flow for RCP with that for selective cerebral perfusion. METHODS Thirty-two consecutive patients underwent elective surgical repair of an aortic aneurysm involving the aortic arch at Kyushu University Hospital. Retrograde cerebral perfusion was used in 15 patients and selective cerebral perfusion, in 17 patients. Continuous measurement of middle cerebral artery blood flow velocities was performed by transcranial Doppler technique. RESULTS Retrograde middle cerebral artery blood flow velocities during RCP could be measured in only 3 patients, whereas middle cerebral artery blood flow velocities during selective cerebral perfusion could be measured in all but 1 woman. The increase in middle cerebral artery blood flow velocities after RCP was significantly greater than that after selective cerebral perfusion. CONCLUSIONS The measurement of middle cerebral artery blood flow velocities with transcranial Doppler technique is practicable during selective cerebral perfusion but difficult during RCP. The increase in middle cerebral artery blood flow velocities after RCP indicates reactive hyperemia and reflects the critical decrease in cerebral blood flow during this type of perfusion.

Novel device to change left ventricular shape for heart failure treatment: device design and implantation procedure.

The Myocor Myosplint is designed to decrease left ventricular (LV) wall stress by changing LV shape, thus improving contractile function in dilated hearts. This shape change is accomplished by surgically placing three Myosplints perpendicular to the LV long axis, drawing the LV walls inward, and creating a symmetric, bilobular LV. Specially designed instruments aid in the precise delivery of these devices. The purpose of this study was to test the safety and feasibility of the procedure in dogs. Dilated cardiomyopathy was induced in 40 healthy dogs (26.3 ± 1.7 kg) by ventricular pacing at 230 beats per minute for an average of 25 ± 4 days. Using epicardial echocardiography, we placed the Myosplints across the LV chamber, avoiding the major coronary arteries, papillary muscles, and mitral valve. Once placed, the Myosplints were used to draw the LV walls inward to a prescribed distance. In all cases, we successfully implanted three Myosplints without using cardiopulmonary bypass. There were no complications related to the device or procedure. Myosplint implantation to change LV shape is safe and repeatable on a beating cardiomyopathic canine heart. Further study of the procedure will be needed in humans.

Inhibition of lipid peroxidation with the lazaroid U74500A attenuates ischemia-reperfusion injury in a canine orthotopic heart transplantation model☆☆☆★★★♢

BACKGROUND The lazaroid U74500A is a 21-aminosteroid that inhibits lipid peroxidation and attenuates ischemia-reperfusion injury. We examined the effect of U74500A on heart preservation with the use of a clinically relevant canine orthotopic heart transplantation model. METHODS AND RESULTS Six donor dogs (group L) were pretreated intravenously with U74500A (10 mg/kg), and the dogs without pretreatment served as a control (group C, n = 6). The donor heart was preserved in cold University of Wisconsin solution for 24 hours. The heart was then transplanted orthotopically. Myocardial biopsy was performed to measure the adenosine triphosphate level at the end of ischemia. Before reperfusion, recipients in group L received another dose of U74500A (10 mg/kg) intravenously. After 3 hours of reperfusion, left ventricular function was evaluated by left ventricular pressure-volume relations with the use of a Millar catheter and conductance catheter, thereby deriving the slope of the end-systolic pressure-volume relation, the slope of the stroke work-- end-diastolic volume relation, and the slope of the maximum dP/dt--end-diastolic volume relation. At the same time, serum creatine kinase MB isoenzyme and lipid peroxide levels were measured. The slopes of the end-systolic pressure-volume relation, the stroke work--end-diastolic volume relation, and the maximum dP/dt--end-diastolic volume relation for group L were significantly higher than those for group C. The adenosine triphosphate levels for group L were significantly higher than those for group C. Serum creatine kinase MB isoenzyme and lipid peroxide levels for group L were significantly lower than those for group C. CONCLUSIONS Inhibition of lipid peroxidation by the administration of U74500A was effective for 24-hour canine cardiac preservation. These results indicate that U74500A is a promising agent for heart allograft preservation.

Mid-term follow-up of the status of Gore-Tex graft after extracardiac conduit Fontan procedure

OBJECTIVE Extracardiac conduit Fontan procedure (ECFP) using Gore-Tex graft has been performed with increasing frequency for the patients with functional single ventricle. However, lack of growth potential and longevity of the conduit are consistent concerns and main points of criticism of the ECFP. In this study, we investigated the mid-term status of the Gore-Tex graft used in the ECFP by comparing the internal diameter of the graft with the inferior vena cava (IVC) diameter at 1 month and 5.2 years after the ECFP. METHODS Of 79 patients who underwent ECFP using Gore-Tex graft between November 1997 and December 2007, 33 patients who had completed cardiac catheterization at 1 month (21-73 days) and 5.2 years (3.3-9.6 years) after the ECFP were included in this study. We measured the internal diameter of the Gore-Tex graft and IVC at both catheterizations retrospectively. RESULTS The size of the Gore-Tex graft used in the ECFP was 16 mm in 17 patients, 18 mm in 9 patients, and 20mm in 7 patients. Laminar flow through the conduits was maintained without any stenosis or kinking of the graft in these 33 patients. No intervention or reoperation related to the extracardiac conduit has been required. There were no significant differences in mean cross-sectional area (CSA) of the conduits at 1 month versus 5.2 years after the ECFP for each conduit size, and no significant changes in the conduit-to-IVC CSA ratio (0.98+/-0.40 vs 0.82+/-0.21 for 16 mm, 1.09+/-0.30 vs 0.92+/-0.33 for 18 mm, and 1.16+/-0.55 vs 0.94+/-0.44 for 20mm conduit). CONCLUSIONS The conduit CSA and conduit-to-IVC CSA ratio remained unchanged in small caliber grafts down to 16 mm at 5.2 years after the ECFP. However, further investigation is necessary to evaluate the fate of the Gore-Tex graft and late hemodynamics in the patients with small conduits after they achieve full somatic growth.

An evaluation of the use of new Doppler methods for detecting longitudinal function abnormalities in a pacing-induced heart failure model.

BACKGROUND Doppler tissue echocardiography and color M-mode Doppler flow propagation velocity have proven useful in evaluating cross-sections of patients with left ventricular (LV) dysfunction, but experience with serial changes is limited. PURPOSE AND METHODS We tested their use by evaluating the temporal changes of LV function in a pacing-induced congestive heart failure model. Rapid ventricular pacing was initiated and maintained in 20 dogs for 4 weeks. Echocardiography was performed at baseline and weekly during brief pacing cessation. RESULTS With rapid pacing, LV volume significantly increased and ejection fraction (57%-28%), stroke volume (37-18 mL), and mitral annulus systolic velocity (16.1-6.6 cm/s) by Doppler tissue echocardiography significantly decreased, with ejection fraction and mitral annulus systolic velocity closely correlated (r = 0.706, P <.0001). In contrast to the mitral inflow velocities, mitral annulus early diastolic velocity decreased steadily (12.3-7.3 cm/s) resulting in a dramatic decrease in mitral annulus early/late (1.22-0.57) diastolic velocity with no tendency toward pseudonormalization. The color M-mode Doppler flow propagation velocity also showed significant steady decrease (57-24 cm/s) throughout the pacing period. Multiple regression analysis chose mitral annulus systolic velocity (r = 0.895, P <.0001) and propagation velocity (r = 0.782, P <.0001) for the most important factor predicting LV systolic and diastolic function, respectively. CONCLUSIONS Doppler tissue echocardiography and color M-mode Doppler flow could evaluate the serial deterioration in LV dysfunction throughout the pacing period. These were more useful in quantifying progressive LV dysfunction than conventional ehocardiographic techniques, and were probably relatively independent of preload. These techniques could be suitable for longitudinal evaluation in addition to the cross-sectional study.

Bilateral Axillary Arterial Perfusion in Surgery on Thoracic Aorta

Bilateral axillary arterial cannulation for selective cerebral perfusion might minimize cerebral embolic complications during surgery on the ascending aorta and aortic arch. From March 2002 through February 2004, bilateral axillary arterial perfusion was applied in 12 consecutive patients (mean age, 61.3 years). Operative procedures were total arch replacement in 8 patients, hemiarch replacement in 1, and ascending aorta replacement in 3. Antegrade selective cerebral perfusion was established through vascular grafts anastomosed to the bilateral axillary arteries and a perfusion catheter placed directly into the left carotid artery. Bilateral axillary arterial perfusion through the grafts was successful in all patients. There were no early or late deaths and no incidence of neurologic deficit. There were no complications related to cannulation of the axillary arteries. Bleeding, temporary renal failure, acute respiratory distress syndrome, and graft infection occurred in one patient each; all recovered from these complications. Bilateral axillary arterial perfusion is feasible and effective for brain protection during surgery on the ascending aorta and aortic arch.

Preload-adjusted maximal power: a novel index of left ventricular contractility in atrial fibrillation.

Background: Left ventricular contractility in atrial fibrillation is known to change in a beat to beat fashion, but there is no gold standard for contractility indices in atrial fibrillation, especially those measured non-invasively. Objective: To determine whether the non-invasive index of contractility “preload-adjusted PWRmax” (maximal ventricular power divided by the square of end diastolic volume) can accurately measure left ventricular contractility in a beat to beat fashion in atrial fibrillation. Methods: Atrial fibrillation was induced experimentally using 60 Hz stimulation of the atrium and maintained in 12 sheep; four received diltiazem, four digoxin, and four no drugs (control). Aortic flow, left ventricular volume, and left ventricular pressure were monitored simultaneously. Preload-adjusted PWRmax, the slope of the end systolic pressure–volume relation (Emax), and the maximum rate of change of left ventricular pressure (dP/dtmax) were calculated in a beat to beat fashion. Results: Preload-adjusted PWRmax correlated linearly with load independent Emax (p < 0.0001) and curvilinearly with load dependent dP/dtmax (p < 0.0001), which suggested the load independence of preload-adjusted PWRmax. After five minutes of diltiazem administration, preload-adjusted PWRmax, dP/dtmax, and Emax fell significantly (p < 0.0001) to 62%, 64%, and 61% of baseline, respectively. Changes were not significant after five minutes of digoxin (103%, 98%, and 102%) or in controls (97%, 96%, and 95%). Conclusions: Preload-adjusted PWRmax correlates linearly with Emax and is a useful measure of contractility even in atrial fibrillation. Non-invasive application of this method, in combination with echocardiography and tonometry, may yield important information for optimising the treatment of patients with atrial fibrillation.

Use of transesophageal echocardiography for postoperative evaluation of right ventricular function.

BACKGROUND No method has been available to assess the right ventricular (RV) pressure-volume relation in the operating room or intensive care unit. Left ventricular cross-sectional area measured by echocardiography using the technology of automated border detection has been used to construct left ventricular pressure-area (P-A) loops. In the human right ventricle, however, this approach has not been validated. METHODS We recorded RV P-A loops in 14 patients in the intensive care unit using transesophageal echocardiography. Multiple RV P-A loops were obtained by reducing preload with intravenous nitroglycerin, thereby elucidating the end-systolic P-A relation. RESULTS With an incremental dose of dobutamine, the slope of the RV end-systolic P-A relation increased (from 4.56+/-2.42 to 7.34+/-3.62 mm Hg/cm2, p<0.01), with no change in the x-axis intercept, which implied increased contractility. Furthermore, in the operating room we validated the use of RV cross-sectional area as a surrogate for RV volume by demonstrating the close correlation between the stroke area (maximal RV area minus minimal RV area) and stroke volume (r = 0.962; p<0.0001). CONCLUSIONS Transesophageal echocardiography with automated border detection is a promising tool for elucidating RV function through the analysis of RV P-A loops.

Cleveland clinic CorAide blood pump circulatory support without anticoagulation.

The Cleveland Clinic CorAide left ventricular assist system consists of a permanently implantable centrifugal pump in which the rotating assembly is completely suspended and noncontacting. A series of chronic animal in vivo studies were conducted to evaluate the biologic effects of CorAide circulatory support without the use of anticoagulation therapy. The CorAide pump was implanted in six calves (five calves for 21 to 32 days and one calf for 95 days). The first five calves received intravenous heparin during the early postoperative periods (2–7 days). Heparin administration was then discontinued and no other anticoagulant drugs were used for the duration of the experiments. The last calf did not receive any anticoagulant except for a bolus dose of heparin (200 U/kg) during surgery. Hemodynamics were stable in all six calves, with a mean pump flow of 5.6 ± 1.2 L/min and mean arterial pressure of 100 ± 4 mm Hg. The blood pump surfaces were clean of thrombus in all six calves. Significant findings at autopsy were limited to one case of renal infarction. There was no incidence of mechanical failure, bleeding, or device infection. The CorAide pump can be safely run with minimal or no anticoagulant therapy.

Effect of phosphodiesterase III inhibitor on contractility, afterload, and vascular capacitance during right heart bypass preparation.

OBJECTIVES Phosphodiesterase III inhibitors, which have both positive inotropic and vasodilatory effects, occasionally cause hypotension due to afterload reduction and possibly due to preload reduction caused by the increase in vascular capacitance. METHODS Six open-chest adult mongrel dogs were used to compare the effects on left ventricular contractility, afterload, and vascular capacitance of the phosphodiesterase III inhibitor, olprinone, with those of dobutamine using a right-heart-bypass model. Contractility and afterload were evaluated by the left ventricular pressure-volume relations with the use of a conductance catheter to derive the end-systolic elastance (Ees) and the effective arterial elastance (Ea). Vascular capacitance change was evaluated by reservoir volume change under a constant bypass flow (80 ml/kg per minute). RESULTS Ees increased significantly both with dobutamine (7.6 +/- 2.8 to 14.3 +/- 4.8 mmHg/ml, p < 0.05) and with olprinone (7.6 +/- 2.9 to 11.5 +/- 4.2 mmHg/ml, p < 0.05). Ea did not change with dobutamine (14.4 +/- 3.5 to 14.5 +/- 3.6 mmHg/ml, p = 0.9), whereas it decreased with olprinone (14.0 +/- 4.1 to 11.4 +/- 3.8 mmHg/ml, p = 0.093). Reservoir volume increased after the infusion of dobutamine (-94.0 +/- 39.8 ml), and decreased after the infusion of olprinone (-114.0 +/- 62.3 ml). The difference was statistically significant (p = 0.007). The reservoir volume change indicated that vascular capacitance decreased with dobutamine, and increased with olprinone. CONCLUSIONS Pre- and afterload reduction of olprinone combined with the positive inotropic effect are useful in treating congestive heart failure and managing low cardiac output syndrome after cardiac surgery.