Simulated left ventricular aneurysm and aneurysm repair in swine.

Patch reconstruction of left ventricular aneurysm may be superior to linear closure, but this hypothesis has not been tested experimentally. Accordingly, six anesthetized domestic pigs were instrumented to measure regional left ventricular wall thickening, stroke volume, systolic left ventricular pressure, and myocardial oxygen consumption. With total bypass and cardioplegia, a 6 by 8 cm Dacron patch was inserted into the anteroapical left ventricle. Simulations were as follows: left ventricular aneurysm, patch open; patch reconstruction, 50% patch plication; standard repair, ventriculotomy edges approximated. Global function, from stroke work (stroke volume x integral of left ventricular pressure)-left ventricular end-diastolic pressure curves, was depressed in all three simulations compared with control. A tendency for stroke work to be greater for standard repair than for left ventricular aneurysm and patch reconstruction at higher preloads was not statistically significant. Mechanical efficiency, from stroke work/myocardial oxygen consumption (joules per milliliter oxygen per beat), was 2.43 +/- 0.52 (mean +/- standard error of the mean) (control), 2.22 +/- 0.94 (standard repair), 1.27 +/- 0.39 (patch reconstruction), and 1.09 +/- 0.37 (left ventricular aneurysm) (no significant differences). Regional work was calculated as regional left ventricular wall thickening x integral of left ventricular pressure. The slope of the regional work-end-diastolic wall thickness relation decreased in the posterior wall 14.0 +/- 2.9 (control) versus 8.4 +/- 2.0 (left ventricular aneurysm), 6.9 +/- 1.4 (patch reconstruction), and 7.4 +/- 1.4 (standard repair) (p less than 0.05). In the anterior wall, contractility did not change significantly (7.4 +/- 1.2, control; 7.8 +/- 2.7, left ventricular aneurysm; 5.0 +/- 0.4, patch reconstruction; and 5.3 +/- 0.4, standard repair). Decreased end-diastolic wall thinning anteriorly suggested tethering. These results in the normal left ventricle suggest that patch ventriculoplasty is of no greater benefit than linear repair. Either repair may impede function of adjacent myocardium through restriction of regional diastolic lengthening.

Effects of perfusion-induced edema on diastolic stress-strain relations in intact swine papillary muscle.

The mechanism through which edema reduces left ventricular compliance has not been defined. Accordingly, diastolic properties of in situ left ventricular swine papillary muscles were studied in three groups: control (n = 6, 4 degrees to 6 degrees C), edematous (150 mOsm/L coronary perfusion, n = 6, 4 degrees to 6 degrees C), and ischemic contracture (n = 8, 28 degrees C). Lagrangian stress (sigma) and strain (epsilon) were calculated from slow stretch data and approximated by sigma = alpha(e beta epsilon-1). The natural logarithm of stress versus strain was linear over the physiologic range of 0.05 < strain < 0.40. Hypotonic perfusions (1 L x 3) progressively shifted the stress-strain relationship upward and to the left. Compared to baseline, alpha increased significantly (p < 0.05) after perfusion 3 (6.7 +/- 2.1 baseline, 12.2 +/- 6.6 perfusion 1, 12.7 +/- 3.5 perfusion 2, and 42.9 +/- 16.3 gm/cm2 perfusion 3). The constant beta did not change significantly (13.0 +/- 1.5 baseline, 13.1 +/- 1.6 perfusion 1, 13.2 +/- 1.6 perfusion 2, and 14.1 +/- 1.4 perfusion 3). Right ventricular water content increased after each perfusion (77.1% +/- 1.4% baseline, 81.6% +/- 1.3%, 84.7% +/- 1.5%, and 86.9% +/- 1.7%, p < 0.05). With ischemic contracture, alpha increased from 61.9 +/- 17.8 to 173.1 +/- 61.5 gm/cm2 (p > 0.05) and beta increased insignificantly from 6.5 +/- 0.6 to 10.6 +/- 1.8 (p = NS). In the control group all variables were unchanged after 210 minutes. We conclude that myocardial stiffness increases with myocardial edema. This may explain decreased compliance in the edematous left ventricle.

Effects of crystalloid, blood, and University of Wisconsin perfusates on weight, water content, and left ventricular compliance in an edema-prone, isolated porcine heart model.

Coronary perfusion with blood and cardioplegic solutions was examined in isolated, arrested, hypothermic porcine hearts. Myocardial water content, heart weight, and left ventricular diastolic pressure-volume curves were measured before and after coronary perfusion. Statistics were based on exponential curve fitting to pressure-volume data and analysis of variance. Thirty-two pig hearts were divided into five experimental groups and a control group; after control measurements, each experimental group underwent three successive coronary perfusions with 1 L of unmodified blood or a solution of controlled osmolarity, 150 mOsm/L (diluted Plegisol solution), 280 mOsm/L (Plegisol solution and albumin), 334 mOsm/L (University of Wisconsin solution), or 380 mOsm/L (Stanford solution). After each perfusion, measurements were repeated. All experiments were completed within 90 minutes. The first perfusion was delayed 20 minutes after excision of the heart to allow for instrumentation. Each experimental group demonstrated a statistically significant increase in heart weight and myocardial water content and a significant decrease in left ventricular compliance after perfusion. Changes were less pronounced with blood than crystalloids. Edema effects were minimized but not prevented by hyperosmolarity. University of Wisconsin solution appeared unique in minimizing progressive edema after the first perfusion. Over the 81 perfusions studied, changes in left ventricular compliance were linearly related to heart weight and water content. We conclude that in this model, in which edema sensitivity is increased by delayed perfusion and venous occlusion, edema is minimized but not eliminated by whole blood and University of Wisconsin solution. The model appears useful in assessing properties of cardioplegia vehicles intended for use in the injured myocardium.

Quantitative effects of myocardial edema on the left ventricular pressure-volume relation. Influence of cardioplegia osmolarity over two hours of ischemic arrest.

We previously studied edema and left ventricular pressure-volume relations in a porcine heart model in which edema occurred even with hyperosmolar crystalloid cardioplegia. This susceptibility to edema was attributed to venous occlusion and an initial 20-minute period of ischemia. Results did not demonstrate reversal of edema by hyperosmolar perfusates. Accordingly, in the present study, heart weight, myocardial water content, and left ventricular pressure-volume curves were measured before and after perfusion-induced edema in eight isolated, arrested, hypothermic porcine hearts. Cardioplegic solution was infused 2.1 +/- 0.8 minutes after the onset of ischemia, and the atrioventricular ring was not clamped during the administration of cardioplegic solution. Cardioplegic solution (1 L) was infused at intervals of 33 +/- 6 minutes at 4 degrees C. Solution osmolarity was 380 (Stanford solution) or 294 mOsm/L (Plegisol solution). The perfusion sequence was 380-1, 380-2, 294-1, 380-3. Pressure-volume relations were assessed with the use of left ventricular volume at a pressure of 10 mm Hg and the ventricular chamber stiffness constant, beta, derived from P = alpha e beta V. Perfusions 380-1 and 380-2 did not affect the pressure-volume curve. Perfusion 294-1 increased heart weight and water content (p < 0.05) and decreased left ventricular volume at 10 mm Hg compared with perfusions 380-1, 380-2, and 380-3. In addition, beta increased (0.023 +/- 0.005 versus 0.029 +/- 0.006, p < 0.05) after perfusion 294-1, compared with 380-1. Correlation coefficients for linear regressions between left ventricular volume at 10 mm Hg and heart weight and water content were r = 0.84 and r = 0.70, respectively. We conclude that under conditions similar to those used clinically, the left ventricle of the pig does not develop edema with Stanford solution (380 mOsm/L). Edema does follow Plegisol solution (294 mOsm/L) cardioplegia. Edema and reduced compliance are incompletely reversed by hypertonic cardioplegia. The porcine left ventricle can usefully replicate the clinical model.

Comparison of the one-and-a-half-year results of closure of patent ductus arteriosus by transcatheter coils placement with surgical ligation.

Patent ductus arteriosus (PDA) is a common type of congenital cardiovascular lesion. It usually needs surgical ligation in a full-term baby after 1 year of age. Transcatheter implantation of coils was introduced for the closure of small- to moderate-sized PDA in 1992. From November 1995 to November 1998, the authors closed the PDA in 153 patients by transcatheter implantation of coils and by surgical ligation in 10 patients. One hundred fourteen of them were studied for more than 1(1/2) years. The regular follow-up studies, including physical examination; electrocardiography; and pulsed, continuous-wave, and color Doppler flow mapping, were performed on day one and day 2, and 1 week, 1 month, 3 months, 6 months, and 1 year after the procedure. The results of the closure of PDA by surgical ligation or coil placement were compared and analyzed in all the patients.

The influence of myocardial edema after coronary perfusion on left ventricular compliance of isolated ischemic porcine hearts.

The effects of myocardial edema on left ventricular (LV) compliance were studied in the isolated, arrested, hypothermic porcine heart. Myocardial water content, heart weight, and diastolic pressure-volume curves were measured before and after coronary perfusion with different coronary perfusates used to induce edema. Five control hearts without coronary perfusion showed no significant changes in LV compliance after 90 minutes of ischemia as assessed by the exponential ventricular stiffness constants, beta, (0.016 +/- 0.003 vs 0.018 +/- 0.007) and by corresponding volume at 15 mmHg LV filling pressure (LVV-15, 77 +/- 15 ml vs 77 +/- 14 ml). Sixteen pig hearts were divided into three experimental groups; after control measurements, each group underwent coronary perfusion with one liter of a solution of graded osmolarity, 380 (n = 6), 280 (n = 5), or 150 (n = 5) mOsm/L. Following perfusion, measurements were repeated. Each group demonstrated increasing heart weight (233 +/- 16 g vs 259 +/- 24 g, 380 group; 186 +/- 23 g vs 228 = +/- 24 g, 280 group; 190 +/- 20 g vs 254 +/- 34g, 150 group; p less than 0.05) and decreasing LVV-15 (81 +/- 13 mL vs 67 +/- 10 mL, 81 +/- 11 mL vs 57 +/- 16 mL, 77 +/- 14 mL vs 21 +/- 11 mL, respectively, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Risk factors for mortality in primary isolated coronary artery bypass grafting surgery.

BACKGROUND AND PURPOSE: Identifying the risk factors for mortality in coronary artery bypass grafting (CABG) surgery is important to improve surgical results. The purpose of this study was to identify the risk factors for mortality in primary isolated CABG in a series of Taiwanese patients. METHODS: Medical records of 914 patients who underwent primary isolated CABG surgery in Veterans General Hospital-Taipei during the period from January 1, 1991, to December 31, 1995, were reviewed. Eighteen clinical and seven operative variables were included in the univariate and multivariate analyses to identify the determinants of mortality in CABG surgery. RESULTS: Thirty-one patients (3.4%) died within 30 days after surgery; 41 (4.5%) died during hospitalization for the procedure. After univariate and multivariate analyses, emergency surgery, history of myocardial infarction, concomitant peripheral artery occlusive disease (PAOD), and prolonged cardiopulmonary bypass (CPB) were found to be significant determinants of mortality in primary isolated CABG. Other variables, including age, sex, angina class, NYHA class, diabetes mellitus, the number of anastomoses, aortic cross-clamp time, stenosis of the left main coronary artery, the number of stenotic coronary arteries, history of congestive heart failure, and a left ventricular ejection fraction less than 35%, were not significant determinants of mortality. Patients undergoing emergency surgery were found to be at highest risk of mortality. CONCLUSIONS: Patients undergoing emergency surgery who had a history of myocardial infarction, concomitant PAOD, or prolonged CPB were at higher risk of mortality in CABG surgery. More comprehensive techniques in myocardial protection, surgical procedures, and postoperative care should be used in the treatment of high-risk patients to reduce mortality.

Absorbable PDS-II suture and nonabsorbable polypropylene suture in aortic anastomoses in growing piglets.

The long-term outcome of vascular anastomoses in children can be compromised by stenosis when the growth of the anastomosis does not match that of the vessels. This can be influenced by the suture material. We evaluated the suitability of the new generation of polydioxanone (PDS-II), an absorbable synthetic monofilament suture, in vascular surgery, in terms of permitting normal growth of aortic anastomoses. Ten piglets underwent primary end-to-end anastomosis of the thoracic aorta, five with PDS-II suture and five with conventional polypropylene (Prolene) suture. Six months after surgery, an aortogram was obtained for each animal. The piglets were then killed and the aortas were sent for pathologic examination. Complete absorption of suture material with slight dilatation of the anastomoses was found in all five pigs in the PDS-II suture group. We also found thrombus formation in one pig in this group. Mild stenosis of the anastomotic site was noted in all five pigs in the polypropylene suture group, but no intraluminal thrombus formation was seen. The degree of dilatation or stenosis within each group was not significantly different when intraluminal diameters were compared at three distinct sites in the reconstructed aorta (p > 0.05). The differences in vascular growth between the two groups were also not significant (p > 0.05). Histologic examination revealed less tissue reaction in the PDS-II suture group than in the polypropylene suture group. Thus, PDS-II seems to be a suitable suture material for anastomoses as far as vascular growth is concerned, but the possibility of aneurysm formation secondary to dilatation of the anastomotic site should be kept in mind.

Experimental implantation of human umbilical vein grafts in dogs.

Locally produced human umbilical vein grafts (HUVG), using glutaraldehyde as a stabilizing agent, were implanted into 24 mongrel dogs. Different arterial bypass procedures, using HUVG, were carried out in three experimental groups. In Group I, 2 dogs underwent femorofemoral crossover bypass procedures and 6 dogs received aortoiliac bypass procedures. Thrombus formation was found in all HUVG implants of Group I. In Group II, 8 dogs received abdominal aorta HUVG interposition. In Group III, 8 dogs received abdominal aorta HUVG bypass procedures. Patent HUVG implants without thrombus formation, demonstrated by postoperative angiogram, were found in 6 dogs of Group II and 5 dogs of Group III. Morphological and histological studies of the patent HUVG implants retrieved after sacrifice showed on sign of rejection, biodegeneration, or aneurysmal formation. Our preliminary experience with this cost-effective locally produced human umbilical vein graft material was promising and may pave the way to further clinical applications.

[Humoral factors in the modulation of sustained discharges of polymodal nociceptors].

By using a model of sustained discharges of polymodal nociceptors (PMN) due to injection of a compound algogenic substance into the skin in anesthetized rats, it was found that stimulation of the sciatic nerve inhibited or facilitated at first and then inhibited the PMN sustained discharges markedly. In a crossperfused preparation, stimulation of the sciatic nerve of donor rat caused the similar effects on sustained discharges of PMN of the recipient rat. Injection of the animal serum after stimulation of the sciatic nerve affected PMN activity obviously. The inhibitory course of most units could not be reversed by naloxone. In the animal tolerance to morphine, the effects of stimulation of the sciatic nerve could still be obtained. Preadministration of reserpine almost completely abolished the facilitatory effect. The results indicate that sustained activity of PMN could be modulated by some humoral factors due to somatic afferents. The inhibitory substances in the humoral factor seem to be both opioid and nonopioid in nature. The facilitatory substance seem to be a catecholamine.

Transcatheter stent treatment for congenital peripheral pulmonary arterial stenosis.

A total of 5 Johnson and Johnson stents were implanted in two patients with significant residual peripheral pulmonary arterial stenosis. These were a 15-year-old boy with post-open heart surgery for tetralogy of Fallot and a 3 8/12 year-old boy with D-transposition of great vessels. Immediately after balloon dilatation and implantation of the stents, the diameter of the narrowing pulmonary arteries increased significantly from 6.0 +/- 0.8 mm to 13.5 +/- 1.7 mm (P < 0.001) and the systolic pressure gradients across the stenosis of peripheral pulmonary artery dropped significantly from 33.0 +/- 16.0 mmHg to 10.2 +/- 4.4 mmHg (P < 0.01). One year later, repeated cardiac catheterization was performed on both patients. In the patient with tetralogy of Fallot, a 20 mmHg pressure gradient was found between the main and left pulmonary artery. This patient then received another stent implantation to release the residual stenosis. The boy with D-transposition of great vessels had only 9 mmHg gradient between main and right pulmonary artery. Transcatheter placement of the stent is a feasible and effective method to treat certain patients with significant pulmonary arterial stenosis if surgical correction can not be performed.

The pressure waveform of coronary sinus in human hearts.

BACKGROUND: The pressure waveform of coronary sinus in human hearts has never been well described. Retrograde cardioplegia perfusion has become a popular method of myocardial protection in recent years, and identification of the pressure waveform of the coronary sinus might help intubate the coronary sinus in retrograde cardioplegia perfusion by differentiating it from that of the right atrium. The purpose of this study is to identify the pressure waveform of the coronary sinus. METHODS: We inserted a catheter into the coronary sinus under direct vision via a right atriotomy after completion of open heart operation in eight patients. The pressure waveforms of coronary sinus and central venous line, as well as the electrocardiogram (EKG), were recorded simultaneously after the patient was stable and weaned from the cardiopulmonary bypass. The recorded pressure waveforms of coronary sinus and central venous line were compared. RESULTS: The pressure waveform of coronary sinus was found to have three peaks, more prominent than those of the central venous line waveform. CONCLUSIONS: The pressure waveform of coronary sinus could be distinguished from that of the central venous line. The difference might help coronary sinus cannulation for retrograde cardioplegia perfusion.

[Double aortic arch associated with severe left ventricular dysfunction--a case report].

A case of a 3-month-old male infant with severe LV dysfunction and a complete double aortic arch (both arches patient) is reported. The right dominant aortic arch runs retroesophageally to the right and joins with the left smaller arch to form the descending thoracic aorta on the right side while the ligamentum arteriosum was located in its normal position (the left side). Through a left thoracotomy, the smaller left arch and the ligamentum were divided to relieve the obstruction of the trachea from compression of the vascular ring. Postoperative convalescence was good. Further follow up of this patient after 9 months showed that there was neither any respiratory failure nor any heart failure sign present, though severe LV dysfunction persisted.

Influence of ventricular septal defect type on surgical results in children with tetralogy of Fallot.

BACKGROUND: Tetralogy of Fallot (TOF) with subpulmonary ventricular septal defects (VSD) is relatively more common among Orientals than among Occidentals. This study assessed the influence of type of VSD on surgical results in children with TOF. METHODS: Fifty-one patients with TOF (age range, 14 months to 11 years, mean 40.7 months, median 30 months, 29 boys, 22 girls) who underwent total correction by a single surgeon between January 1992 and December 1995 were retrospectively studied. Of the 51 patients, 17 patients with subpulmonary VSD were classified as group I. The remaining 34 patients with perimembranous VSD were classified as group II. All patients underwent a combined transatrial and transpulmonary surgical approach. Early postoperative results were evaluated 7 to 10 days after surgery and late postoperative results were evaluated 1 year after surgery. RESULTS: There were no statistically significant differences between the two groups in age, sex, body weight, pulmonary to systemic flow ratio, pulmonary to aortic annulus diameter ratio or preceding palliative shunt or balloon pulmonary valvuloplasty. Nevertheless, group I patients had better oxygen saturation preoperatively (84.2 +/- 4.4% vs 80.3 +/- 7.6%, p = 0.037). During surgery, the transannular patch rate was higher in group I (100% vs 73.5%, p = 0.003). The cardiopulmonary bypass time, postoperative stay in the intensive care unit, duration of chest tube placement, early postoperative residual VSD rate, and early and late postoperative residual pulmonary stenosis rate were not significantly different between the groups. However, late postoperative residual VSD rate was 33.3% in group I and 6.45% in group II, which was statistically significant (p = 0.029). There were no significant differences in arrhythmia between the two groups. CONCLUSIONS: Patients with TOF with subpulmonary VSD had a better preoperative oxygenation, higher transannular patch rate during surgery and a higher incidence of late residual VSD than those with TOF with perimembranous VSD.

Synchronous carotid endarterectomy and myocardial revascularization.

BACKGROUND: The management of the coexisting extracranial carotid and coronary disease is still controversial. We reviewed our experience in synchronous operation for both diseases in Veterans General Hospital-Taipei. METHODS: From Jan. 1988 to Nov. 1992, the synchronous carotid endarterectomy and myocardial revascularization were performed in nine patients with the mean age of 66.6 +/- 11 years. Five had symptomatic extracranial vascular disease or stabilized neurological deficits, and four had asymptomatic carotid bruits. Four had bilateral hemodynamically significant carotid stenosis. NYHA functional class III-IV was noted in three patients. Triple-vessel coronary disease was documented in 6 patients including one with left main lesion more than 50%. Eight had previous or recent myocardial infarction and four had moderate to severe left ventricular dysfunction noted on left ventriculography. RESULTS: All nine patients received unilateral carotid endarterectomy and a mean number of 2.8 distal anastomosis. Operative number of 2.8 distal anastomosis. Operative mortality within 30 days was zero and morbidity was noted in two patients. One patient was CVA and the other one was perioperative myocardial infarction. Late mortality occurred in previous two patients with morbidity. Late morbidity was mainly due to cardiac rather than neurological problems. CONCLUSIONS: If long-term natural history of coronary or carotid artery disease could be actually altered by surgery, a systemic evaluation for possible multifocal atherosclerosis is mandatory. By following a proposed guideline, synchronous operation is appropriate for a subgroup of patients with coexisting carotid and coronary artery disease.

Minimally-invasive, direct coronary artery bypass grafting.

BACKGROUND: Minimally-invasive, direct vision coronary artery bypass grafting (MIDCAB) is a new surgical technique performed via limited thoracotomy in a beating heart without cardiopulmonary bypass. METHODS: From June 1996 to December 1996, MIDCAB was performed in 12 patients (all male, average age, 65.9 years). In 11 patients with left anterior descending coronary artery lesions, thoracotomy was performed via the left, fourth intercostal space and the pericardium was incised to identify the target site. About 8 cm of the left internal mammary artery was harvested. Bilateral anterolateral thoractomy was performed in one patient with left anterior descending and right coronary artery lesions. Anastomosis was performed under direct vision in the beating heart without cardiopulmonary bypass. RESULTS: MIDCAB was performed successfully without morbidity. The patients' average stay in the intensive care unit was 1.8 days. No patient had any early cardiac event requiring additional surgery or percutaneous transluminal coronary angioplasty. Postoperatively, all patients were asymptomatic and their recovery was uneventful. CONCLUSIONS: Our initial experience indicates that MIDCAB offers good results and is a treatment option for selected patients with left anterior descending and/or right coronary artery lesions.

A new autoperfusion technique for aortic reconstruction of suprarenal aortic aneurysm.

Visceral ischemia is a serious factor in the postoperative morbidity and mortality of suprarenal aortic reconstruction. We reported two patients of suprarenal aortic aneurysm involving visceral arteries, who received successful Dacron graft replacement by using Pruitt-Inahara balloon catheters as an autoperfusion for preservation of the visceral organs. No visceral organ ischemia occurred postoperatively except in patient 2 who had preoperative chronic renal failure and persistent renal failure after the operation. The renal function recovered gradually during the follow-up period. Both patients are doing well at the present time. The new autoperfusion technique can directly deliver normothermic blood from the arterial cannula at proximal aorta to the individual visceral arteries by using the balloon perfusion catheters. It is simple, safe, easily instituted and the used products are readily obtainable. It allows the surgeon to provide an effective protection of visceral organs for the suprarenal aortic reconstruction.

Surgical repair of Ebstein's anomaly.

BACKGROUND: Ebstein's anomaly represents a congenital structural deformity of the tricuspid valve associated with a wide spectrum of morphologic and physiologic abnormalities. Valvuloplasty and tricuspid valve replacement are the main surgical treatments. Plication of the atrialized right ventricle and valvuloplasty of the tricuspid valve can achieve satisfactory clinical results. Two surgical techniques, known as Danielson's and Quaegebeur's methods, are often used clinically. This study was conducted to compare the postoperative results between both methods in treatment of Ebstein's anomaly. METHODS: Valvuloplasty of tricuspid valve and the plication of atrialized right ventricle were performed in 8 out of 17 patients with Ebstein's anomaly in our hospital from January 1986 to August 1996. Danielson's method was used in six of eight patients, and Quaegebeur's method was used in the remaining two patients. There were three males and five females, aged from 8 months to 61 years (mean: 14.1 years). RESULTS: All patients achieved clinical improvement in cardiothoracic ratio and heart functional class. Cardiac arrhythmia was the likely cause of death in two patients treated by Danielson's method, and one patient developed complete atrioventricular (A-V) block postoperatively. By Quaegebeur's method, all patients survived, but a permanent pacemaker was implanted for both patients due to their preoperative complete A-V block. CONCLUSIONS: Both methods achieved satisfactory postoperative results. However, Quaegebeur's method seems to be more effective because it provided a simultaneous reconstruction of both tricuspid valve and right ventricle without the need for additional excision of the right atrium.

Intravenous pretreatment with magnolol protects myocardium against stunning.

Magnolol, an antioxidant, has been reported to possess various protective effects on the cardiovascular system. However, its effect on myocardial stunning has not been elucidated. The purpose of this study was to investigate the antistunning effect of magnolol by evaluating the recovery of regional myocardial function after 10-minute coronary artery occlusion in anesthetized, open-chest rabbits. There was no significant hemodynamic change after intravenous infusion of magnolol. Systolic wall thickening fraction (WThF) measured with an epicardial Doppler sensor in animals pretreated with normal saline and vehicle solution remained significantly depressed (60 +/- 7% and 77 +/- 4% of baseline WThF, respectively) 3 hours after coronary artery reperfusion (CAR). Pretreatment with magnolol (10(-7) and 10(-6) g/kg, intravenous infusion) significantly enhanced the recovery of systolic wall thickening fraction (98 +/- 1 and 99 +/- 1% of baseline WThF, respectively) 60 minutes after CAR. This study demonstrated that intravenous pretreatment with magnolol protected myocardium against stunning.