Effects of wrapping tightness on acute cardiac function in dynamic cardiomyoplasty.

BACKGROUND: It has not been clarified how tightly the heart should be wrapped for maximal augmentation of cardiac function in cardiomyoplasty. METHODS: Hearts in acute failure induced by propranolol were wrapped with the left latissimus dorsi muscle, loosely (loose CMP), moderately (moderate CMP), and tightly (tight CMP) in each of 5 pigs. To measure the pressure between the latissimus dorsi muscle and the left ventricle (LV), a Millar pressure catheter with a latex balloon was placed on the anterior wall of the LV. Left ventricular wall tension was calculated according to Laplace's law, using the difference between the LV pressure and the balloon pressure. RESULTS: In the loose CMP, moderate CMP, and tight CMP groups, the mean balloon pressures during unassisted beats were 8.2, 10.4, and 13.2 mm Hg, respectively. During unassisted beats, the mean LV wall tension values were 38,683, 29,938 (p < 0.05 versus loose CMP), and 26,652 (p < 0.05 versus loose CMP) dynes/cm, respectively, the peak LV pressures were 76.8, 73.8, and 65 (p < 0.05 versus loose CMP) mm Hg, respectively, and the stroke volumes were 12.8, 9.2, and 8.5 (p < 0.05 versus loose CMP) mL, respectively. During assisted beats, the mean LV wall tension values were 20,059, 11,290, and 7,893 (p < 0.05 versus loose CMP) dynes/cm, respectively, the peak LV pressures were 94.1, 98.1, and 92.0 mm Hg, respectively, and the stroke volumes were 13.8, 11.6, and 9.4 (p < 0.05 versus loose CMP) mL, respectively. CONCLUSIONS: During unassisted beats, tight CMP (13 mm Hg) had the advantage of diminishing LV wall tension, but the disadvantage of diminishing LV pressure and stroke volume, compared with loose CMP (8 mm Hg). Moderate CMP (10 mm Hg), however, had the advantage of diminishing LV wall tension without a decrease in LV pressure and stroke volume.

Distinctive microcirculation of the brain during cerebral perfusion by observation with a CCD microscope.

Establishment of safer cerebral protection remains an important issue in reducing cerebral complications during aortic arch repair. Various cerebral perfusion techniques have been used. Recently, the usefulness of retrograde cerebral perfusion (RCP) combined with hypothermia was reported. The authors evaluated the cerebral microcirculation during RCP by direct observation with a charge-coupled device (CCD) microscope. In six craniotomied, anesthetized swine, cardiopulmonary bypass was established by arterial perfusion through the femoral artery and venous drainage from the right atrium. The authors observed cerebral arteriolae and venulae on the brain surface. Each swine was cooled to a brain temperature of 20 degrees C. Perfusion was stopped, RCP was initiated with oxygenated blood through the superior vena cava, and cerebral perfusion pressure (CPP) was gradually increased. During antegrade cerebral perfusion (ACP), homogeneous vascular flow was observed in all models. During RCP, retrograde vascular flow was generated in four of the six models, but homogeneous retrograde vascular flow was achieved in arteriolae and venulae in only two models at a CPP of greater than 20 mmHg. It is suggested that homogeneous and effective retrograde perfusion may not be achieved at a CPP of less than 20 mmHg, and that RCP causes uneven microcirculation of the brain with a disadvantageous effect on cerebral protection when compared with ACP.

Monitoring and regulating latissimus dorsi muscle performance for circulatory assist.

The purposes of this study were monitoring and regulating latissimus dorsi muscle (LDM) performance with muscle internal pressure and thickness, and with burst stimulation parameters, respectively. The unconditioned LDM flap of a pig was connected to a measurement system to examine force and contraction length. Internal pressure was measured using a catheter pressure transducer with a fluid-filled balloon inserted into the muscle, and correlated linearly with force during both contraction and relaxation. During contraction, thickness change correlated linearly with contraction length and the area enclosed within an internal pressure-thickness curve, and the X-axis was correlated linearly with muscle work. Stroke work increased incrementally according to the pulse width up to 6.72 msec or burst rate up to 120 Hz, and then plateaued at 240 Hz. The authors conclude that muscle work during contraction could be monitored with internal pressure and thickness, and that stroke work could be regulated with pulse width or burst rate.

Immunohistochemical morphometry of pancreatic islets in the cat.

The application of immunohistochemical technique with antisera for glucagon (Glu), insulin (Ins), somatostatin (Som) and pancreatic polypeptide (PP) to serial sections of the cat pancreas permitted the quantitative evaluation of the population of 4 endocrine cell types and that of the area, larger diameter and density of islets. The pancreas was divided macroscopically into the 4 portions, duodenal, gastric, anastomotic and splenic. The duodenal portion was characterized by the localization of PP-immunoreactive (IR) cell-rich islets, the dissemination of PP-IR cells in the exocrine parenchyma and the absence of Glu-IR cells. In the duodenal portion, the area, the larger diameter and the density of islets were significantly smaller than those in the other 3 portions. On the contrary, the other 3 portions were marked with the deficiency of PP-IR cells and the existence of Glu-IR cell-rich islets. Ins-IR cells, identified as compact cell masses without any other types of cells, occupied a major part of every islet, composing much the same population throughout the 4 portions. The Som-IR cell population appeared to be closely in parallel with the Glu-IR cell population in all of the portions. It is concluded that all islets are similar in the Ins-IR cell population, but different in the complementary arrangement of Glu- and PP-IR cells. Based on this difference, 2 types of islets can be classified.

Pituitary dependent hyperadrenocorticism in a cat.

A cat that was suspected some insulin resistance was diagnosed as pituitary dependent hyperadrenocorticism from an adrenocorticotropic hormone (ACTH) stimulation test, dexamethasone suppression test and measure of endogenous plasma ACTH concentration. Histopathological examination revealed chromophobe adenoma in pituitary gland and hyperplasia in adrenal cortex.

Anatomical localization of sympathetic postganglionic and sensory neurons innervating the pancreas of the cat.

Sympathetic postganglionic and sensory neurons were labeled by injecting a mixed solution of horseradish peroxidase and wheat germ agglutinin conjugated horseradish peroxidase into the splenic portion or the duodenal portion of the cat pancreas. Labeled postganglionic neurons (about 25,000 cells) were located bilaterally in the celiac and cranial mesenteric ganglia (91%), mainly in celiac ganglia, and in the paravertebral ganglia T5 to L7 (9%), especially in T13 to L2. Labeled sensory neurons (about 2,700 cells) were found bilaterally in the dorsal root ganglia T3 to L5, chiefly in T10 to L1. Some differences were found in the localization of labeled postganglionic and sensory neurons between the two portions of the pancreas. Injection in to the splenic portion revealed more labeled neurons in ganglia on the left side, while injection into the duodenal portion gave rise to a greater number of labeled neurons on the right side. Paravertebral and dorsal root ganglion cells innervating the splenic portion were concentrated in fewer ganglia than those supplying the duodenal portion. Compared to the splenic portion, the duodenal portion tended to be innervated by more cranially located neurons in paravertebral and dorsal root ganglia. These neurons probably control the secretion of the endocrine and exocrine pancreas, but the differences in the localization of the labeled neurons between the two portions may be related to the different intraabdominal positions of the two portions of the pancreas.

Immunohistochemical studies of neural elements in pancreatic islets of the cat.

The cat pancreas has a complex neural supply comprising adrenergic, cholinergic and peptidergic innervations. To elucidate the localization of neuropeptides and enzymes in neural elements of the cat pancreatic islets, single or double immunohistochemical staining was performed using avidin-biotin-peroxidase complex and/or peroxidase-antiperoxidase methods. In intrapancreatic ganglia, numerous galanin (Gal)- or vasoactive intestinal polypeptide (VIP) immunoreactive (IR) ganglion cells were seen. Many nitric oxide synthase (NOS)- or cholecystokinin (CCK). IR and a few bombesin (Bom)- or substance-P (SR)-IR ganglion cells were also observed. Intrapancreatic ganglion cells were surrounded by numerous VIP- or SP-IR, many Bom- or neuropeptide Y (NPY)-IR, several calcitonin gene-related peptide (CGRP)- or peptide histidine isoleucine IR and a few NOS- or CCK-IR nerve terminals. In pancreatic islets, many VIP-IR nerve terminals were located predominantly around insulin (Ins)-IR cell masses and many tyrosine hydroxylase-IR nerve terminals were demonstrated in the core of Ins-IR cell masses as well as around them. Gal-, NPY-, SP- or CGRP-IR nerve terminals were found much more frequently within Ins-immunonegative cell areas than in Ins-IR cell masses. These observations may provide a morphological basis for the possible transmitting or modulating role of neuropeptides in pancreatic islets of the cat.

Immunohistochemical colocalization of serotonin, aromatic L-amino acid decarboxylase and polypeptide hormones in islet A- and PP-cells of the cat pancreas.

To establish which monoamines are elaborated in the pancreatic islet cells of cats, the pancreatic tissue was studied by immunohistochemistry on serial or mirror tissue sections. Glucagon-containing A-cells reacted immunohistochemically with antisera directed against serotonin and aromatic L-amino acid decarboxylase, though the half of A-cells immunostained with glucagon antiserum did not show the colocalization with serotonin. Pancreatic polypeptide-containing PP-cells also showed immunoreactivity for antisera directed against serotonin and aromatic L-amino acid decarboxylase. However, PP-cells exhibiting immunoreactivity for serotonin were very few in number. The overlapping areas of the two types of cell represented only a small proportion of the PP-cells. Immunoreactivity for aromatic L-amino acid decarboxylase was observed within almost all A- and PP-cells. Since aromatic L-amino acid decarboxylase is an enzyme involved in the synthesis of serotonin, it is concluded that pancreatic islet A- and PP-cells in cats have the ability to elaborate serotonin. Contrarily, islet B- and D-cells showing immunoreactivity for insulin and somatostatin antisera, respectively, did not react with antisera directed against serotonin and aromatic L-amino acid decarboxylase.

[A surgically treated case of ruptured true aortic arch aneurysm in association with Stanford type A chronic dissection].

A 72-year-old woman was admitted to our hospital because of hemosputum. Enhanced CT showed ruptured true aortic arch aneurysm. True aortic arch aneurysm ruptured at distal portion of aneurysm. The aorta was chronically dissected from an entry proximal to ruptured portion, to ascending aorta. Ascending aorta to aortic arch was replaced with 20 mm gelatin sealed graft under selective cerebral perfusion with hypothermia. Post-operatively tracheostomy was done because of respiratory failure, and there was some leak from distal anastomosis portion which was 42 mm in diameter at the operation. So replacement of descending thoracic aorta was performed using elephant trunk of the previously replaced graft. Post-reoperative course has been uneventful. She weaned from respiratory support. True aortic arch aneurysm combined with Stanford type A dissection is very rare. We presented ruptured true aortic arch aneurysm in association with Stanford type A chronic dissection which had an entry in true aneurysm.

Blood supply to the latissimus dorsi muscle and muscle performance during co- or counterpulsatile stimulation for circulatory assist.

For the application of the latissimus dorsi muscle (LDM) to circulatory assist, the muscle is stimulated with co- or counterpulsation during the cardiac cycle. The purpose of this study was to evaluate the blood supply to the LDM and its muscular performance during each respective stimulation. The origin of the LDM was connected to a tension gauge, a potentiometer, and 1 kg of weight in series. The LDM was stimulated at a ratio of 1:1 of heart to muscle contraction for 10 min. Copulsatile stimulation made thoracodorsal arterial flow (TDF) predominant during cardiac diastole. In counterpulsatile stimulation, TDF occurred predominantly during cardiac systole. Between the 2 patterns of stimulation, no significant differences were observed in the mean TDF rate during 1 cardiac cycle. The maximal force, maximal contraction length, and power of the LDM also did not differ significantly. These results suggest that despite the difference of the TDF profile, LDM performance may be comparable between co- and counterpulsatile stimulation for the application of the LDM to circulatory assist.