Donato A. Sisto

Left-to-right ventricular interaction with a noncontracting right ventricle.

UNLABELLEDnLeft ventricular systole is known to contribute to generation of right ventricular pressure and stroke volume. To study the interactions in a dilated noncontractile right ventricle after cardiopulmonary bypass we created a variable volume, neo-right ventricle by excision and replacement of the right ventricular free wall with a xenograft pericardial patch. We investigated the interactions in eight dogs with neo-right ventricle, instrumented to measure cardiac pressures and cardiac output in control conditions (n = 69) and during partial pulmonary artery occlusion (n = 50).nnnRESULTSnThe size of the neo-right ventricle was increased from original right ventricular volume V0 to V1 (V1 = V0 + 54 +/- 23 ml), V2 (V2 = V0 + 124 +/- 85 ml), and V3 (V3 = V0 + 223 +/- 162 ml). Cardiac output increased with increasing left ventricular end-diastolic pressure, indicating that the Frank-Starling mechanism was operating in the left ventricle. However, cardiac output decreased with increasing neo-right ventricular size (p < 0.001) and during pulmonary artery occlusion (p < 0.001). Maximal neo-right ventricular pressure was a linear function of the maximal left ventricular pressure at each neo-right ventricular size and decreased with the increase in neo-right ventricular size (p < 0.001), both in control conditions and during pulmonary artery occlusion (p < 0.004). Stroke work of the neo-right ventricle and left ventricle decreased with increasing neo-right ventricular size (p < 0.002). The relationship between neo-right ventricular stroke work and left ventricular stroke work at different neo-right ventricular sizes was linear both in control conditions and during pulmonary artery occlusion: in control Y = 0.24X (r = 0.968, n = 69); in pulmonary artery occlusion Y = 0.35X (r = 0.986, n = 50). In both conditions the intercept of the linear relationship was not significantly different from zero (p < 0.974 in control; p < 0.614 in pulmonary artery occlusion). The slope was significantly increased in pulmonary artery occlusion (p < 0.001).nnnCONCLUSIONnLeft ventricular contraction contributes 24% of left ventricular stroke work to the generation of right ventricular stroke work via the septum in the absence of a contracting right ventricle; this increases to 35% in the face of increased pulmonary afterload. This mechanism can maintain adequate global cardiac function in the case of a noncontracting right ventricle while right ventricular volume is kept small and afterload is not increased. The interventricular interaction of the ventricles must be considered when patients with postbypass right ventricular failure are treated.

Metabolic and immune effects of arginine in postinjury hyperalimentation

Nitrogen balance and thymic immune function studies were carried out in rats subjected to anesthesia, jugular vein catheterization, and bilateral femoral fractures, who were then given for 5 days: A) D5W; B) D20 FreAmine II (total arginine 1.55 gm/L); or C) D20 FreAmine III (4.05 gm of arginine/L). Administration of hypercaloric amino acid mixtures had strong positive effects on nitrogen retention and thymic function when compared to isotonic dextrose infusion. The administration of solution C had the most positive effect on nitrogen balance and on thymic immune function. The data suggest that increased arginine administration may prove beneficial to injured patients.

Thymic stimulatory actions of arginine.

Various arginine HCl supplements (0.5-3%), half added to a basal commercial rodent chow (1.8% arginine) and half to the drinking water, were given to 8- to 9-week-old male CBA/J mice for 6 days. Control animals were fed the basal chow and drank tap water. All mice ate and drank ad libitum. Weight gain and food intake were similar in all groups. All arginine supplements increased significantly: thymic weight (average 22%), thymic lymphocyte content (average 45%), and the in vitro reactivity of thymic lymphocytes judged by the incorporation of 3H-leucine into the TCA-precipitable protein fraction in response to stimulation by phytohemagglutinin and concanavalin A. All these thymic effects resulted from the 0.5% arginine hydrochloride supplement; further increases in arginine supplementation did not increase these effects. These data suggest that supplemental arginine may improve host defence mechanisms and thereby may play an important role in the care of severely injured or ill patients, since it is well established that their defense mechanisms are reduced.

New Applications of Two-Dimensional Transesophageal Echocardiography in Cardiac Surgery

This article describes new applications of two-dimensional transesophageal echocardiography (2D-TEE), including (1) detection of pleural fluid (PF) and atelectasis (AT), and (2) evaluation of various cannulation techniques. The left and right pleural spaces were visualized by rotating the probe counterclockwise and clockwise, respectively, from the four-chamber view. PF was depicted as a crescent-shaped echo-free space, enclosed by the lung and posterior chest wall on both sides. AT was often accompanied by PF and was depicted as a less echogenic area in the lung parenchyma. During removal of PF, the echo-free space gradually decreased in size to the point of disappearing completely, while the lung parenchyma expanded and became more echogenic. TEE was advantageous in detecting PF and AT located in the most dorsal parts of the pleural space and lung parenchyma. The aorta acted as an acoustic window on the left side. TEE was found useful in evaluating the cannulae position of the intraaortic balloon pump (IABP) and ventricular assist device (VAD), and femoral cannulae for cardiopulmonary bypass (CPB). During use of the IABP, the chamber and shaft were visualized clearly and both malposition of the catheter tip and malfunction of the balloon were easily detected. For VAD, TEE readily showed the collapse of the ventricular cavity due to excessive drainage of blood from the left ventricle, as well as the favorable result of immediate reduction of flow rate. For femorofemoral extracorporeal bypass, TEE detected improper position of the venous cannula. These new applications of TEE can be performed with minimal manipulation of the probe, enabling early detection of the problems and initiating timely and appropriate therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Thymic inhibition of wound healing: Abrogation by adult thymectomy

Abstract It has been previously observed that the thymus and wound respond in a similar manner, i.e., agents that enhance thymic function increase wound healing, while factors which decrease thymic function impair healing. In order to elucidate if the thymus has a direct influence on wounds, we have studied wound healing in adult rats who have undergone thymectomy at 4–8 weeks of age. In three separate experiments we found that thymectomized rats had fresh wound breaking strengths significantly greater than sham-thymectomized rats. There were no differences noted in the amount of reparative collagen accumulated in subcutaneously implanted polyvinyl alcohol sponges or in the breaking strength of wound strips fixed in 10% formalin, which maximally cross-links the collagen present; the ratios of fixed to fresh wound breaking strengths were significantly greater in sham-thymectomized rats. Rats who had undergone thymectomy with immediate intraperitoneal placement of Millipore chambers containing autologous thymic fragments had wound breaking strengths similar to sham-thymectomized or intact animals. We conclude that thymectomy at 4–8 weeks of age increases wound maturation and collagen cross-linking. This suggests that the thymus normally has an inhibitory effect on wound healing and a role of T-suppressor cells on this process is postulated.

Arginine Stimulates Thymic Immune Function and Ameliorates the Obesity and the Hyperglycemia of Genetically Obese Mice

The effect of 6-day dietary arginine supplementation on the weight gain, blood glucose, thymus weight, thymic lymphocyte content, and in vitro thymic lymphocyte immune reactivity was studied in obese (C57BL/6J-OB/)B) and heterozygous lean mice. Control mice were fed a commercial laboratory chow (1.8% arginine content) and drank tap water, while supplemented mice were given 0.5% arginine in the chow and 0.5% arginine solution for drinking. All mice ate and drank ad libitum. Supplemental arginine significantly decreased the weight gain (1.2 g vs. 2.2 g, p less than 0.01) and blood glucose levels (303 mg% vs 236 mg%, p less than 0.02) of the OB/OB mice; no such effects were noted in the lean heterozygotes, all of which had normal blood glucose levels. OB/OB mice had thymus glands which weighed less and contained significantly fewer lymphocytes than their lean littermates. In vitro mitogen-stimulated thymic lymphocyte protein synthetic rates were equal in chow-fed lean and OB/OB mice. In both groups, supplemental arginine significantly increased thymus weight, the number of thymic lymphocytes per gland, and thymic lymphocyte immunoreactivity in vitro. The hormonal secretagogue activity of arginine on the pituitary may explain its beneficial effects on the rate of weight gain, hyperglycemia, and depressed thymic immune function of OB/OB mice.

Is use of the intraaortic balloon pump in octogenarians justified

Increasing numbers of octogenarians are seen in the operating room or critical care unit with circumstances for which intraaortic balloon pump (IABP) assistance is appropriate, but it has been suggested that the complication rate for IABP use in octogenarians is excessive. From 1980 to 1990, 25 octogenarians needed an IABP in our institution, as an adjunct to operation in 20 patients (1 had repair of a ventricular rupture and 19 underwent coronary grafting); 5 patients did not have operation. The indications for IABP use were unstable angina, 12 (48%); cardiogenic shock, 10 (40%); and difficulty weaning off cardiopulmonary bypass, 3 (12%)--these 3 were the only ones who had insertion through a femoral cut-down. No serious insertion difficulties were noticed with the percutaneous route in the other 22 patients. Without operation, 4 of 5 patients died in the hospital (80%), and the 5th died 2 years 8 months after discharge. After operation, there were two hospital deaths (10%) and two late deaths, neither from cardiac causes. A fatal outcome occurred in 6 of 9 patients with cardiogenic shock. Intraaortic balloon pump-related complications were rare, minor, and unrelated to IABP assistance duration, which ranged from 24 to 146 hours (mean, 49.9 hours). No long-term vascular complications resulted. Hospital stay averaged 22.2 days. At follow-up from 9 to 81 months (mean, 51.8 months), of the 16 survivors, 12 (75%) were in New York Heart Association class I/II and 2 each were in classes III and IV.(ABSTRACT TRUNCATED AT 250 WORDS)

Transient Loss of Vision as the Presenting Symptom of Papillary Fibroelastoma of Aortic Valve

Cardiac papillary fibroelastomas are benign endocardial papillomas. They may arise from atrial or ventricular endocardium but most commonly are located in cardiac valves. Their papillary structure, with loose, friable projections, results in a high tendency for embolism. Tumor fragments often embolize to the coronary, systemic, or cerebral arterial systems. Thus, acute myocardial infarction, cerebrovascular accident, or peripheral arterial occlusion have resulted from these tumors. Retinal artery embolism is a rare complication of papillary fibroelastoma, and only five such patients have been reported in the English-language literature. We describe a 64-year-old woman who presented with transient painless loss of vision and was found to have a large papillary fibroelastoma on the right coronary cusp of the aortic valve by transesophageal echocardiography. The tumor was successfully removed at surgery.