High flow demand on small arterial coronary bypass conduits promotes graft spasm.

Despite the superior long-term patency of arterial grafts, surgeons are often reluctant to use arterial grafts on coronary vessels that supply large areas of myocardium because postoperative shock may occur. We hypothesized that supramaximal flow through small arterial conduits would decrease distal intraluminal pressure, thereby reducing afterload on the smooth muscle and rendering the arterial graft vulnerable to spasm. Fourteen internal thoracic and eight gastroepiploic arteries were harvested from adult pigs (220 to 250 pounds). Arteries were mounted on a computer-controlled perfusion system with inflow pressure at 80 mm Hg and outflow resistance adjusted to simulate normal (in situ) or supramaximal (coronary artery bypass graft) flow demands. Artery pressures and flow rates were measured at baseline and after norepinephrine was added to the system. Internal thoracic arteries had no hemodynamic response to norepinephrine at normal flow. Under supramaximal flow demands, large internal thoracic arteries (2.5 to 3.0 mm) had no hemodynamic response to norepinephrine. However, for small internal thoracic arteries (2.1 to 2.9 mm), norepinephrine reduced distal internal thoracic arterial pressure (63.2 +/- 2.2 to 27.0 +/- 1.9 mm Hg) and flow rate (99.4 +/- 5.0 to 45.4 +/- 2.7 ml/min, median effective dose = 9.12 x 10(-9) mol/L). Under normal flow demands, the flow rate in gastroepiploic arteries (1.0 to 2.0 mm diameter) decreased (14.1 +/- 0.5 to 4.8 +/- 0.8 ml/min, p < 0.05) only at high concentrations of norepinephrine (median effective dose = 1.26 x 10(-6) mol/L). Supramaximal flow demands reduced distal gastroepiploic arterial pressure (77.5 +/- 0.5 to 49.5 +/- 3.8 mm Hg, p < 0.05), which resulted in a greater decrease in flow rate (80.0 +/- 3.7 to 6.8 +/- 1.6 ml/min, p < 0.05) at lower concentrations of norepinephrine, (median effective dose = 3.24 x 10(-8) mol/L, p < 0.05). In four studies in internal thoracic arteries and eight in gastroepiploic arteries, arteries were cut in half, reattached, and reperfused. The proximal half of the internal thoracic artery did not respond to norepinephrine, but the distal half had a 53% +/- 7% decrease in flow. Both gastroepiploic artery halves reacted and flow rate decreased by 88% +/- 2% (proximal half) and 89% +/- 3% (distal half). In conclusion, small arterial conduits develop large transconduit pressure gradients under supramaximal flow demands. Under these conditions, arteries are very sensitive to vasoconstrictors and flow may cease with higher drug concentrations.(ABSTRACT TRUNCATED AT 400 WORDS)

Pulmonary artery balloon counterpulsation in the management of right heart failure during left heart bypass.

Pulmonary artery balloon counterpulsation was instituted in 10 pigs when right ventricular failure limited cardiac output. Global myocardial depression was produced by infusion of propranolol, and the left ventricle was fully supported by left heart bypass. A stable model of failure was achieved in six pigs. Following application of pulmonary artery balloon counterpulsation right atrial pressure decreased from 18.2 +/- 2.1 to 15.9 +/- 2.5 mm Hg (p less than 0.05). Cardiac output increased from 416 +/- 94 to 758 +/- 127 ml/min (p less than 0.001). Right ventricular stroke work increased from 0.29 +/- 0.07 to 0.65 +/- 0.12 gm X m. (p less than 0.05). There was no cardiac output before or after institution of balloon counterpulsation in four pigs studied during ventricular fibrillation or asystole. We conclude that pulmonary artery balloon counterpulsation improved cardiac output and right ventricular stroke work in a model of right ventricular failure where the pulmonary circulation was unaltered and the left ventricle supported by left heart bypass. Balloon counterpulsation was not effective during ventricular fibrillation or asystole. Pulmonary artery balloon counterpulsation should be considered when right ventricular failure limits cardiac output during left heart bypass.

Pericardial fluid adenosine in ischemic and valvular heart disease.

Adenosine released by ischemic myocardial cells stimulates coronary artery vasodilation. Measurement of adenosine concentrations in pericardial fluid in animal models of myocardial ischemia has been used to study the process of adenosine release. To determine whether pericardial fluid adenosine concentrations are increased in human ischemic heart disease, adenosine concentrations were measured in pericardial fluid in 23 subjects undergoing open-heart surgery for coronary artery disease. The results were compared with adenosine concentrations measured in pericardial fluid obtained from 20 subjects undergoing surgery for valvular heart disease. Adenosine concentrations also were measured in pleural fluid obtained during internal mammary artery bypass grafting. Adenosine concentrations were significantly increased in subjects with coronary artery disease compared with fluid obtained from subjects with valvular heart disease (2.47 +/- 0.24 vs 1.36 +/- 0.21 [SEM] microM [p = 0.0013]). Adenosine concentrations were higher in pleural fluid than pericardial fluid from the same individuals. Adenosine concentrations were significantly correlated with pericardial fluid cell counts and lactate dehydrogenase concentrations (r = 0.48; p = 0.0012 and r = 0.77, p = 0.0001, respectively). The results are consistent with myocardial release of adenosine in ischemic heart disease. If adenosine concentrations in pericardial fluid approximate those in myocardial interstitial fluid, sufficient adenosine is present to stimulate adenosine receptor activation in coronary artery smooth muscle.

Bilateral vs single internal thoracic artery grafting for left main coronary artery occlusion.

This study was conducted to compare the coronary flow distributed by single and bilateral internal thoracic artery (ITA) grafts in the setting of the left main coronary occlusion. Ten dogs underwent coronary artery bypass grafting through a left thoracotomy, off pump, using a brief local occlusion to perform the anastomosis. Dogs were randomly assigned to receive either a single left ITA (LITA) graft to the circumflex coronary artery (CFX), or bilateral ITA grafts, with additional placement of the right ITA (RITA) to the left anterior descending artery (LAD). After the grafts were placed, the left main coronary artery was ligated. Electromagnetic flows were obtained in the LAD and the CFX proximally and distally to ITA grafts in both groups before grafting and after grafting. ITA flow in situ was also measured before rotation from the chest wall. Total left ventricular flow requirements were satisfied equally well by either a single LITA graft (116.7 +/- 11.6 mL/min) or bilateral ITA grafts (total, 116.8 +/- 9.6 mL/min divided as LITA, 55.9 +/- 7.4 mL/min; RITA, 60.9 +/- 12.0 mL/min). When two grafts were replaced, competitive flow in the proximal regions of both native vessels was noted, although basal flow requirements were maintained. When an individual graft was occluded in the bilaterally grafted system, the remaining graft immediately recruited the additional flow, demonstrating that either right or left ITA can support flow demands five to six times higher than in situ chest wall flow (RITA, 21.9 +/- 3.1 mL/min; LITA, 22.3 +/- 4.9 mL/min). These data suggest that in this canine model, a single ITA graft can support the entire flow requirements of the left ventricle. Assuming no intervening stenosis is present in native coronary systems, bilateral ITA grafting may provide a margin of safety, but under resting conditions, provides no perfusion advantages over a single ITA graft.

Instrumentation for minimally invasive internal thoracic artery harvest.

The anterior fourth interspace minithoracotomy is our current choice for exposure of the anterior myocardial wall for minimally invasive coronary bypass grafting procedures. This approach provides direct access to the left anterior descending coronary artery for anastomosis, and good exposure of the midsegment of the internal thoracic artery. We describe the use of instrumentation that facilitates the harvest of the left internal thoracic artery under direct vision. The use of this retractor system, which elevates the third and fourth and depresses the second and first ribs, permits better visualization of the internal thoracic artery and allows for proximal internal thoracic artery harvest without rib resection.

Anastomotic complications in minimally invasive coronary bypass grafting.

BACKGROUND: Anterior wall myocardial revascularization through a left anterior minithoracotomy is an increasingly accepted procedure. Technical failure at the anastomotic site, promoting persistent or recurrent angina, is known to occur and may be underrecognized. This report summarizes the incidence of technical failure in an initial clinical experience and describes potential causes of early postoperative complications. METHODS: Between December 1995 and May 1996, 15 patients underwent left internal mammary artery-to-left anterior descending artery revascularization without extracorporeal circulation. The surgical indication was single-vessel coronary disease in all patients. We exposed the left anterior descending artery target site through a 10-cm left anterior fourth space thoracotomy. The fourth costal cartilage was resected and the left internal mammary artery was harvested under direct visualization. Two 4-0 polypropylene sutures snared in tourniquets proximal and distal to the anastomotic site were used to obtain a bloodless field and stabilization of the left anterior descending artery. RESULTS: All patients had procedures initially deemed successful based on disappearance of angina or postoperative transthoracic Doppler examination of the internal mammary artery 3 to 5 days postoperatively. However, 3 patients presented with recurrent angina at 2, 6, and 8 weeks. Angiography or direct visualization at operation demonstrated the technical complication (stenosis at the anastomotic site in 2 and snare injury in the native vessel in 1). Two patients required reoperation. CONCLUSIONS: Initial results with minimally invasive coronary bypass grafting have generated great enthusiasm worldwide, but there is no consensus on how the procedure should be performed. These results suggest that a nonstabilized anastomosis results in an unacceptable failure rate. Furthermore, sutures encircling the left anterior descending artery should not be used for vessel stabilization as injury of the artery may occur.

Successful VATS ligation of a large anomalous branch producing IMA steal syndrome after MIDCAB.

The occurrence of a flow "steal phenomenon" from a large branch of the internal mammary artery (IMA) is rare and its pathogenesis is still controversial. We describe a case of a patent large anomalous left IMA branch which produced recurrent angina 3 years post MIDCAB. Transcatheter coil obliteration of the vessel produced symptomatic relief. However, six months later, chest pains recurred in association with unwinding of the coil and recannulization of the collateral vessel. Successful ligation of the culprit branch using a VATS approach is presented.

Methylene blue guidance for simplified resection of a lung lesion.

A 60-year-old patient returned 1 year after right pneumonectomy with a new primary squamous cell carcinoma of the left lower lobe. Using fluoroscopic guidance, the lesion and the shortest track to the surface were marked by methylene blue preoperatively. The lesion was easily excised by wedge resection without the need for manipulation or deflation of the lung.

A rational approach to the selection of an assist device for the failing right ventricle.

Assist devices have become available for the treatment of right ventricular (RV) failure. The present study assesses the efficacy of pulmonary artery balloon counterpulsation (PABC) in restoring RV output to normal levels. In a porcine model of RV failure during left heart bypass, PABC restored RV output to normal, provided that the RV output was not depressed to less than 50% of baseline values. When RV failure was more severe, PABC was not effective in restoring RV output to base line. This study suggests that a rational approach should be developed for the use of right heart assist devices. In moderately severe RV failure, PABC may be successful in restoring cardiac output to normal. However, in extreme failure a right heart bypass is necessary.

The hemodynamic effects and mechanism of action of pulmonary artery balloon counterpulsation in the treatment of right ventricular failure during left heart bypass.

The efficacy of pulmonary artery balloon counterpulsation (PABC) was evaluated in improving right ventricular (RV) output during left heart bypass for global cardiac failure. In 13 pigs, a 40-ml balloon was positioned within a graft anastomosed to the pulmonary artery distal to the pulmonary valve, and left heart bypass was instituted from the left atrium to the carotid artery. Global myocardial failure was produced by an infusion of propranolol (range, 25 to 78 mg). In this model, RV output decreased despite volume loading to a right atrial pressure of 15 mm Hg and atrioventricular sequential pacing at 100 beats per minute. Pulmonary artery balloon counterpulsation increased both RV output (from 519 +/- 76 to 1,117 +/- 110 ml/min; p less than 0.01) and RV systolic stroke work (from 1.3 +/- 0.4 to 2.3 +/- 0.6 gm-m; p less than 0.01). Right atrial pressure decreased (from 15.5 +/- 0.9 to 10.7 +/- 1.0 mm Hg; p less than 0.01) in 8 of the pigs studied during RV failure. In 5 pigs, ventricular fibrillation occurred without a stable model of RV failure, and there was no cardiac output before or after counterpulsation. The mechanism of action of PABC was studied by placing a flow probe around a large branch of the right pulmonary artery. During RV failure, balloon inflation caused flow through the pulmonary circulation, and ventricular systole resulted in filling of the graft. During ventricular fibrillation, balloon inflation and deflation produced only a to-and-fro movement of blood in the pulmonary artery branch without net forward flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Serious wound infections after minimally invasive coronary bypass procedures.

BACKGROUND: Minimally invasive coronary artery bypass grafting has become an increasingly accepted therapy for selected patients with single-vessel coronary artery disease. Reported morbidity has focused on anastomotic problems, but the occurrence of serious wound complications after these procedures has not been well documented. METHODS: We reviewed our institutional experience with 35 patients to look for the incidence of serious wound complications. RESULTS: Three patients had serious wound problems after minithoracotomy for coronary artery bypass graft procedures. This represents an overall 9% wound morbidity rate and a 100% rate in the obese women. CONCLUSIONS: Wound complications at the incision site after minithoracotomy coronary artery bypass graft procedures seem to occur distinctly in obese women with redundant breasts.

The effects of cardioplegic arrest on right atrial function.

Atrial electrical and mechanical activity persists during cardioplegic arrest. It has been postulated that atrial ischemia may occur and cause deterioration in atrial function. This study was designed to assess the effect of cardioplegic arrest on right atrial function. Twenty-one pigs were placed on cardiopulmonary bypass (CPB), and the right atrium was isolated from the circulation by snaring both venae cavae and incising the coronary sinus. The tricuspid valve was closed through a small right ventriculotomy, and baseline atrial function was assessed using a compliant balloon in the atrium. Fourteen pigs underwent one hour of cardioplegic arrest (7 with cardioplegia alone [CCA group] and 7 with the addition of topical hypothermia [CCA + TH group]) followed by one hour of normothermic reperfusion. Seven other pigs were placed on CPB for the same period of time (CPB group). Atrial electrical and mechanical activity persisted at 45 beats per minute in the CCA group but was virtually abolished in the CCA + TH group. Cardioplegic arrest caused considerable deterioration in right atrial function (developed pressure, 18.9 +/- 0.8 [baseline] versus 14.1 +/- 0.7 mm Hg; p less than 0.05; first derivative of atrial pressure [dP/dt], 187 +/- 19 versus 134 +/- 25 mm Hg per second; p less than 0.05; 60 minutes of reperfusion and balloon volume of 20 ml). It was not affected by topical cooling. Right atrial developed pressure was maintained, but dP/dt was significantly reduced in the CPB group. This study suggests that cardioplegic arrest does not protect the atrium.

Clinical experience with the video-assisted saphenectomy procedure for coronary bypass operations.

BACKGROUND: Leg wound complications after saphenectomy are frequent after coronary bypass operations and have a detrimental effect on postoperative quality of life and treatment cost. To reduce morbidity, we evaluated a new technique of video-assisted vein harvest. METHODS: Between March 1996 and October 1996, 50 patients had video-assisted saphenectomy (VAS) and 40 patients had the standard open technique (control group). An additional 13 patients had both procedures (hybrid group). Level of pain, edema, and wound complications were evaluated at discharge and at 2, 4, and 6 weeks postoperatively. RESULTS: The mean operating time for VAS patients was slightly higher than for control (60.6+/-24.7 minutes versus 53.2+/-21.1 minutes; p > 0.05). The average incision length in VAS patients was 13.8+/-8.8 cm for an average of 3.3 grafts per patient. Three VAS procedures were aborted, two because of time constraints, and one because of bleeding, and a segment of vein was lost to injury. The VAS group had considerably less early postoperative pain than the control group (1.7+/-1.2 versus 4.1+/-1.4 [1 = mild, 10 = severe]; p < 0.005) and edema was similar for both groups. Patients in the hybrid group reported less pain in the VAS-operated leg. Serious wound infection occurred in 4 patients, with 2 patients in the control group requiring reoperation for drainage and flap reconstruction. CONCLUSIONS: Based on this initial experience, VAS harvesting, although initially more time consuming, is a rapidly mastered technique, results in shorter overall incision length, and is associated with considerably less postoperative pain than the standard open technique.

Toward a better understanding of the etiology of left ventricular dysfunction after mitral valve replacement: an experimental study with possible clinical implications.

The relatively high morbidity and mortality of mitral valve replacement (MVR) appears to be related to an impairment in left ventricular (LV) function. This two-part investigation was designed to assess the effect of MVR on global LV function in an isolated heart preparation and to evaluate whether a mitral prosthesis with a flexible annulus would be of benefit. In Part I (14 pigs), the effects of each step in MVR were studied. Division of the chordae tendineae caused a severe deterioration in LV function (systolic pressure, 180 +/- 13 versus 120 +/- 10 mm Hg; p less than 0.05; developed pressure, 167 +/- 13 versus 108 +/- 11 mm Hg; p less than 0.05; first derivative of LV pressure [dP/dt], 2,630 +/- 300 versus 1,610 +/- 180 mm Hg/sec; p less than 0.05; balloon volume, 30 ml). Fixation of the mitral annulus prior to division of the chordae tendineae resulted in a small decrease (not significant) in LV function but had no effect after the chordae tendineae were divided. In Part II (10 pigs), two mitral annular prostheses were studied: a standard rigid prosthesis and a prosthesis of identical size but with a flexible annulus. LV function was better with the flexible than the rigid prosthesis (systolic pressure, 118 +/- 10 versus 89 +/- 5% control, p less than 0.02; developed pressure, 120 +/- 11 versus 87 +/- 5% control; p less than 0.02; dP/dt, 119 +/- 10 versus 85 +/- 4% control; p less than 0.02; balloon volume, 30 ml).(ABSTRACT TRUNCATED AT 250 WORDS)

A physiological approach to surgery for acute rupture of the papillary muscle.

There is controversy regarding the optimal management of patients in whom acute papillary muscle rupture develops. This study evaluates the effect of division of the anterolateral papillary muscle on left ventricular (LV) function and compares two methods of treatment--mitral valve replacement (MVR) and mitral valve repair. Thirteen pigs were placed on cardiopulmonary bypass, and interventions were performed in an isolated beating heart preparation. LV function was assessed with a compliant intraventricular balloon at baseline, after division of the anterolateral papillary muscle (Divided), after repair of the divided papillary muscle (Repair), and finally after MVR. Division of the anterolateral papillary muscle caused a significant deterioration in LV function. Function was maintained at this level after mitral valve repair but deteriorated with MVR. Developed pressure measured at baseline was 179 +/- 13 mm Hg; Divided, 148 +/- 11 mm Hg (p less than 0.05 versus baseline); Repair, 149 +/- 15 mm Hg; and MVR, 95 +/- 8 mm Hg (p less than 0.05 versus Divided) at a balloon volume of 20 ml. These results suggest that LV function is impaired by papillary muscle rupture. Repair of the ruptured papillary muscle is associated with better LV function than is MVR.

Role of graft flow measurement technique in anastomotic quality assessment in minimally invasive CABG.

BACKGROUND: Anastomotic quality is currently the critical issue in minimally invasive coronary surgery. Although little is known about its effectiveness, surgeons routinely assess grafts intraoperatively using flow probes. This study was designed to determine whether mean flow and the pattern of flow tracing in internal mammary artery grafts obtained with a transit-time flow probe are reliable indicators of anastomotic quality. METHODS: Mongrel dogs (n = 14, 30 to 35 kg) underwent off-pump left, right, or left and right internal mammary artery to left anterior descending artery anastomosis (23 grafts). Moderate to severe degrees of stenosis were created at the anastomosis by an additional suture. Internal mammary artery graft flow was measured before and after the stenosis was created with the left anterior descending artery occluded. Angiography was performed at random postoperatively to validate the degree of stenosis. Mean flow and flow tracing morphology were compared under various degrees of stenosis. RESULTS: There were no significant differences in mean graft flow or the morphology of the flow tracing between patent (<15%), mild (<25%), moderate (<50%), and moderately severe (<75%) stenosis. However, mean graft flow decreased (p < 0.05) with severe stenosis (>75%). CONCLUSIONS: Although differences in mean graft flow and graft flow morphology were detectable in anastomoses with severe stenosis (>75%), they were indistinguishable in anastomoses with mild (<25%) to moderately severe (<75%) stenosis. Flow measurement techniques are valuable tools intraoperatively, but surgeons should exercise caution in their interpretation.

Experimental supplemental vein grafting and hypoperfusion syndrome.

An additional saphenous vein graft (SVG) sometimes is required to the same coronary system if acute internal thoracic artery (ITA) graft flow is inadequate. These experiments were conducted to determine the consequences produced by ITA-SVG dual grafting. Fourteen dogs each received two coronary grafts (without bypass, using local occlusion) to the proximal circumflex coronary artery, using the ITA and an SVG, and then the circumflex artery was ligated proximally. Simultaneous flow in both grafts was determined at rest and after pharmacologic (adenosine, phenylephrine) or physiologic (cardiac pacing) stimulation. Serial angiography was performed during the first 4 weeks after grafting to determine patency patterns of the ITAs and SVGs. In the resting heart, flow was 7.5 +/- 1.6 mL/min (17.5%) in the ITA graft and 35.3 +/- 5.2 mL/min (82.5%) in the SVG (mean +/- standard deviation [% total distal perfusion]), and the combined flow was not significantly different from the original native flow. Intravenous adenosine (0.2 mg.kg-1.min-1) preferentially increased both the total ITA flow and its fractional contribution to total distal perfusion (18.4 +/- 3.2 [31.1%]; p < 0.05 versus rest). Saphenous vein graft flow was not changed significantly (40.3 +/- 6.0 mL/min), in part due to a modest decrease in arterial pressure. In contrast, intravenous phenylephrine (0.003 mg.kg-1.min-1) decreased both absolute ITA flow and its relative contribution to distal perfusion (6.1 +/- 1.1 [10.9%]; p < 0.05 versus rest), despite an increased systemic perfusion pressure, which increased SVG flow significantly (50.1 +/- 4.8 [89.1%]; p < 0.05 versus rest).(ABSTRACT TRUNCATED AT 250 WORDS)

Competitive flow from a fully patent coronary artery does not limit acute mammary graft flow.

The shriveled, stenotic mammary graft sometimes observed after internal mammary artery (IMA) to coronary artery bypass grafting has been attributed to competitive flow from the insufficiently stenosed native coronary vessel. To study further the effects of native coronary artery competing flow on IMA graft flow, 10 dogs (mean weight, 23.5 +/- 3.69 kg) underwent coronary artery bypass grafting using the pedicled left IMA anastomosed to a normal, fully patent proximal circumflex (CFX) coronary artery. The procedure was performed through a left thoracotomy, off pump, using a brief local occlusion to perform the anastomosis. Native in situ IMA flow, CFX flow distal to the anastomosis, and IMA graft flow were measured using calibrated electromagnetic flow probes. When the CFX proximal to the anastomosis was occluded transiently, IMA flow increased to supply 100% of the previously measured distal CFX flow (60.2 +/- 7.9 mL/min). When both the IMA graft and CFX proximal to the anastomosis were patent, total distal perfusion was maintained (58.9 +/- 7.8 mL/min) and relative IMA graft flow (26.5 +/- 3.3 mL/min) was proportional to the relative diameter of the IMA graft to the native coronary artery (r = 0.96). The mean flow in the IMA in situ on the chest wall before its division was 23.8 +/- 8.1 mL/min. These results suggest that, at least acutely in a canine model, IMA graft flow is maintained above in situ levels even when grafted to a completely patent coronary artery and that acute competitive flow probably does not cause mammary artery shriveling.

Effect of chronic native flow competition on internal thoracic artery grafts.

Residual competitive flow from the native coronary artery has been proposed as a mechanism that reduces flow in an internal thoracic artery graft (ITA), resulting in narrowing and ultimately failure of the graft. Results from acute experiments have indicated that competitive flow from a fully patent native artery did not abolish ITA graft flow. The present study was designed to examine the consequences of dynamic flow competition between the native vessel and the ITA graft in a chronic model. Fifteen mongrel dogs underwent coronary artery bypass grafting using the pedicled left ITA anastomosed to the normal, fully patent circumflex (CFX) coronary artery. The procedure was performed through a sterile thoracotomy, without systemic cardiopulmonary bypass, using a brief local occlusion to construct the anastomosis. Intraoperatively, ITA flow was measured in situ on the chest wall, before the pedicle was mobilized. Internal thoracic artery graft and distal CFX flow were measured after the anastomosis was completed, with and without brief occlusion of the proximal CFX. Angiography was performed 72 hours, 4 weeks, and 8 weeks later; graft patency and diameter were evaluated. After 8 weeks, open-chest direct flow measurements comparable with the intraoperative assessment were obtained. Two grafts (13%) occluded early, the technical result of poor anastomotic construction. In the 13 remaining animals, all grafts were widely patent at all time points. Internal thoracic artery flow in situ averaged 10.9 +/- 7.8 mL/min (mean +/- standard deviation), and was maintained after grafting (11.5 +/- 4.4 mL/min; p = not significant).(ABSTRACT TRUNCATED AT 250 WORDS)

Right ventricular failure. Pathophysiology and treatment.

The cardiac surgeon is faced with RV failure in two main situations: in isolation or in patients with left-sided cardiac assist. Adequate volume loading, correction of acidosis and oxygenation, cardiac pacing, pharmacologic agents, and systemic intra-aortic balloon pumping allow stabilization in most of these patients. When these measures fail, some form of mechanical assistance of the right ventricle becomes necessary. Balloon counterpulsation in the pulmonary artery improves RV output but does not restore the systemic perfusion if the right ventricle is profoundly depressed. When the right ventricle is profoundly depressed, a mechanical assist pump is the only device capable of restoring systemic perfusion. Like the left ventricle, the right ventricle, given time and support, can recover enough function to allow weaning from the assist device and survival.