Ryuichi Morita

Angiographic demonstration of no-flow anatomical patency of internal thoracic-coronary artery bypass grafts

To clarify the no-flow situation of the stringlike internal thoracic artery graft, we angiographically examined such grafts by temporarily occluding the recipient coronary artery with a percutaneous transluminal coronary angioplasty balloon and were able to reveal anatomical patency of the internal thoracic artery graft in 2 patients 1 year and 3 years after the operations. Thus, there is a possibility that internal thoracic artery grafts may continuously maintain anatomical patency even under no-flow situations just like nonfunctioning collateral vessels and may function properly later as a graft when the native coronary flow decreases. Also, this angiographic technique can be a new method for detecting anatomical patency of no-flow and functionally closed internal thoracic artery grafts.

Systolic and diastolic function after patch reconstruction of left ventricular aneurysms

Left ventricular function after patch reconstruction for postinfarction left ventricular aneurysms is largely unknown. In this study, 16 patients with an anteroseptal-lateral left ventricular aneurysm were treated by reconstruction of the left ventricle using a Dacron patch. Coronary artery bypass grafting was performed concomitantly in 9 patients. The size of the patch used was 57% +/- 19% of the resected myocardial scar area, including the sewing cuff area to be sutured. In these patients, the ejection fraction increased significantly from 0.28 +/- 0.12 to 0.39 +/- 0.12 (p = 0.007) at rest and from 0.32 +/- 0.14 to 0.41 +/- 0.10 (p = 0.008) during exercise. The left ventricular end-diastolic pressure and left ventricular end-diastolic volume index were reduced significantly from 14 +/- 7.0 to 8 +/- 3.2 mm Hg (p = 0.032), and from 178 +/- 116 to 92 +/- 21 mL/m2 (p = 0.016). The peak filling rate was improved significantly from 1.2 +/- 0.47 to 1.8 +/- 0.6/s (p = 0.048) postoperatively. The ratio of the peak flow velocity during the atrial kick phase to the peak flow velocity in the rapid filling phase, at the level of the mitral valve, improved (p = 0.016) after operation and remained improved up to 16 to 24 months after operation. Patch reconstruction of the left ventricle resulted in the recovery of systolic and diastolic function soon after operation, which has persisted into the late postoperative period.

Lower extremity ischemia secondary to internal thpraciccoronary artery bypass grafting

Vascular complications associated with the use of the internal thoracic artery as a conduit for coronary artery bypass are infrequent. However, acute limb-threatening ischemia can occur after the use of the internal thoracic artery for myocardial revascularization when this vessel forms an important collateral to an obstructed aortoiliac artery system. Although this is a rare complication, the consequences are devastating. Due to the risk of peripheral vascular insufficiency, we now perform simultaneous revascularization of the myocardium and the lower extremity when an internal thoracic artery that appears to be a major collateral to the ipsilateral aortoiliac system is used.

A pathohistological and biochemical study of arteriosclerosis in the internal thoracic artery, a vessel commonly used as a graft in coronary artery bypass surgery

Pathohistological and biochemical studies were conducted on the severity of arteriosclerosis in the internal thoracic artery (ITA), an artery commonly used for coronary artery bypass grafting (CABG). For the pathohistological examination, 26 bilateral ITAs and 13 left anterior descending coronary arteries (LADs) obtained in full length from 13 autopsy cases, none of which had died of arteriosclerotic heart disease, were used. The ratio of the thickness of the intima to that of the media (R) was used as the index for arteriosclerosis. ITAs and LADs were classified as grades I to IV according to the value of R. The R of the ITAs was approximately 1/10 that of the LADs (P<0.01). Most ITAs showed a low arteriosclerotic grade, with no variation in arteriosclerosis along their length and a low R in all segments. No difference was found between right and left ITAs. Biochemical examination was conducted on 12 ITAs and 11 LADs, obtained from 12 different and unselected autopsy cases. The lipid content in the vascular wall was determined to evaluate the severity of arteriosclerosis, with the following results: Total cholesterol, 5.5±1.8 and 17.8±13.6 μg/mg wet weight (P<0.05); triglyceride, 90.4±90.3 and 114.4±117.2 μg/mg wet weight (n.s.); and phospholipid, 7.4±3.9 and 11.2±3.9 μg/mg wet weight (P<0.05), respectively, for the ITAs and LADs. These findings thus demonstrate that arteriosclerosis of the ITA in Japanese people is very mild, compared to that of the LAD in the same individuals.

Exercise coronary flow reserve of bilateral internal thoracic artery bypass grafts

We attempted to quantify the exercise coronary flow reserve in 20 patients with bilateral internal thoracic artery grafts to the left coronary arteries (group I) who had complete revascularization. The coronary sinus blood flow was measured by the continuous thermodilution method both at rest and during exercise (50 W for 8 to 9 minutes) approximately 1 month after the operation. These results were compared with 30 patients treated with an internal thoracic artery and saphenous vein grafts to the left coronary arteries (group II) and 9 patients with saphenous vein grafts alone to the left coronary arteries (group III). There were no differences among the three groups in age, sex, number of vessels involved, heart rate, double products, left ventricular (LV) end-diastolic pressure, LV ejection fraction, LV end-diastolic volume, or LV mass at the time of study. None of the 59 patients in the study had abnormally enlarged LV end-diastolic volume or increased LV mass. The postoperative coronary sinus blood flow per 100 grams of LV mass at rest was similar among the three groups (73.0 +/- 28.4 mL/min per 100 g LV mass in group I, 73.4 +/- 31.1 mL/min per 100 g LV mass in group II, and 75.9 +/- 28.5 mL/min per 100 g LV mass in group III [not significant]) and significantly (p < 0.01) increased by exercise, although the differences between groups during exercise were not significant (158.9 +/- 45.9, 153.5 +/- 72.1, and 148.3 +/- 60.0 mL/min per 100 g LV mass, respectively [not significant]).(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamics and coronary blood flow during exercise after coronary artery bypass grafting with internal mammary arteries in children with Kawasaki disease.

BackgroundSaphenous vein grafts (SVG) and internal mammary artery (IMA) grafts have been used for coronary artery bypass grafting. In adult patients with bypass grafting for atherosclerotic coronary artery disease, IMA grafts have been reported to have long-term patency; however, results are conflicting on whether the graft is sufficient to meet increased myocardial oxygen demand during exercise. There have been no studies on hemodynamics and blood flow during exercise after bypass grafting with IMA in pediatric patients with Kawasaki disease. Methods and ResultsWe studied 17 pediatric patients with Kawasaki disease (average age, 7.5 ± 3.1 years), who underwent coronary artery bypass grafting with the IMA. The average number of coronary artery bypass grafts was 2.1 ± 0.7/patient. For all patients, the left IMA was anastomosed to the left anterior descending coronary artery; for eight patients, the right IMA was also anastomosed to the right coronary artery. In addition, 11 SVGs were used. The postoperative patency rates after 1 month were 100% with the IMA graft and 91% with SVG. One year after the operation, the patency rates were 100% with IMA and 50%o with SVG. Hemodynamics during exercise were measured with a bicycle ergometer, and coronary sinus blood flow was measured by the continuous thermodilution method in six patients. The relation between ALVEDP (the difference between left ventricular end-diastolic pressure at rest and during exercise) and ASVI (the difference between the stroke volume index at rest and during exercise) was analyzed. Four of six patients had reduced cardiac function before operation (ALVEDP, positive; ASYI, negative). However, after the operation, all patients demonstrated improvements in cardiac function during exercise (ALVEDP, positive; ASVI, positive). Coronary sinus flow per left ventricular mass increased after operation from 70 ± 46 to 87 ± 56 ml/min at rest (p < 0.05) and from 139 ± 118 to 183 ± 150 ml/min during exercise (p < 0.05). ConclusionsIn conclusion, this study reveals improvements in both hemodynamics and coronary blood flow during exercise after coronary artery bypass grafting with IMA grafts in pediatric patients with Kawasaki disease.

Different responses of coronary artery and internal mammary artery bypass grafts to ergonovine and nitroglycerin in variant angina

The dynamic responses of a coronary artery and an internal mammary artery (IMA) graft to pharmacological intervention were examined by arteriography in 5 patients with variant angina who had undergone coronary artery bypass grafting with an in situ IMA to the left anterior descending coronary artery. Preoperative electrocardiographic findings included elevated ST segments in chest leads during attacks of angina, and all patients had severe fixed lesions in addition to marked spasm of the left anterior descending coronary artery after the administration of ergonovine maleate. Postoperatively with ergonovine stimulation, complete occlusion or marked subtotal narrowing was again observed at the primary fixed lesion in the proximal portion of the left anterior descending coronary artery, but the IMA graft and the coronary artery distal to the anastomotic site maintained satisfactory patency with no further occurrence of anginal pain or ST segment elevation. By computer-assisted graphic analysis, which allows highly reproducible measurements of vascular internal diameters, the diameter of the IMA showed only small changes under ergonovine (p = not significant) or nitroglycerin (p less than 0.05) stimulation in contrast to the marked vascular reactivity of the coronary artery (p less than 0.05 and less than 0.01, respectively). These findings indicate that the IMA graft is unresponsive to ergonovine at least in the amount required to produce coronary artery spasm in patients with variant angina and fixed lesions. The IMA graft appears to function well from a clinical and pharmacological viewpoint in patients with variant angina.

Relations of preoperative hemodynamics and coronary blood flow to improved left ventricular function after valve replacement for aortic regurgitation

In this study of the limits of reversibility of left ventricular function after aortic valve replacement for aortic regurgitation, measurements were made of pre- and postoperative coronary blood flow and left ventricular volumes. Eighteen patients who had undergone aortic valve replacement for pure aortic regurgitation using the Björk-Shiley valve or the Bicerval valve were restudied an average of 8 +/- 3 months after surgery. Postoperative left ventricular end-systolic and end-diastolic volumes returned to near normal values. The slight left ventricular wall thickening apparent before surgery remained unchanged after surgery and, consequently, left ventricular mass, though somewhat reduced, remained abnormally high. Ejection fraction, which was low preoperatively, returned to normal postoperatively. Total coronary sinus blood flow decreased after surgery, but coronary sinus blood flow per 100 g of left ventricular mass increased. This recovery of coronary flow per unit mass was believed to cause the improvement in left ventricular function. A significant correlation was found between postoperative systolic function and preoperative left ventricular end-systolic and end-diastolic volumes, wall thickness and, especially, left ventricular mass, the latter indicating that, if preoperative left ventricular mass is less than 350 g/m2, postoperative improvement of systolic function is attainable. Another significant correlation was indicated by measurements of coronary sinus blood flow per 100 g of left ventricular mass. If this is greater than 35 ml/min before surgery, a postoperative improvement in systolic function to within the normal range may be expected.

Left atrial plication combined with mitral valve surgery in patients with a giant left atrium

The benefits of performing left atrial plication during mitral valve surgery for patients with a giant left atrium were evaluated by analyzing the short- and long-term surgical results and changes in the left atrial dimension (LAD) and respiratory function of 30 patients. Of the 30 patients, 2 (7%) died of multiple organ failure on postoperative days 26 and 117, but no other deaths occurred during the mean follow-up of 5.9±2.1 years. Valve thrombosis was observed in one patient and cerebral complications with no residual deficit were observed in two patients, with a 9-year event-free rate of 87±7%. The LAD decreased significantly from 69.0±8.5 mm to 53.7±9.1 mm (P<0.01) shortly after surgery, and this decrease was maintained even 5 years after surgery (53.3±11.4 mm). The cardiothoracic ratio decreased from 74.8±8.3% to 62.8±9.0% (P<0.01) and the vital capacity of the lungs increased from 71.1±18.0% to 82.9±22.2% (P<0.01). Thus, we conclude that performing left atrial plication during mitral valve surgery is safe and effective for patients with a giant left atrium.

A New Method of Closing the Ventricular Septal Defect in Corrected Transposition of the Great Arteries

A new method of closing a perimembranous malalignment ventricular septal defect (VSD) in corrected transposition of the great arteries (TGA) of the [S,L,L] type is presented. The method consists of combined approaches to the VSD through both a right atriotomy and an aortotomy without a ventriculotomy. The VSD is patched obliquely from the morphological right ventricular side of the septum, cranially through the aortic valve to the left ventricular side of the septum, caudally through the mitral valve. Although this method has been successfully applied in only one adult patient, some advantages may be expected: (1) prevention of trauma to the His bundle, which runs along the anterosuperior rim of the VSD on the left ventricular side; and (2) prevention of trauma to the tricuspid, mitral, and aortic valves without having to open the ventricles. We believe that this new method warrants a further trial as possibly better for closure of the VSD in corrected TGA of the [S,L,L] type.