Left ventricular outflow obstruction: a complication of mitral valvuloplasty.

Thirty-two patients with severe mitral regurgitation underwent Carpentier mitral valvuloplasty. Postoperatively, three of these patients developed clinical and echocardiographic evidence of left ventricular outflow tract obstruction. None of these patients had asymmetric septal hypertrophy or preoperative echocardiographic demonstration of systolic anterior motion of the mitral valve. Outflow obstruction postoperatively was caused by systolic anterior motion of the mitral valve. Because this potential complication of Carpentier mitral valvuloplasty produced significant hemodynamic effects in two patients, echocardiography should be routinely performed after this operation.

Anterior leaflet procedures during mitral valve repair do not adversely influence long-term outcome.

OBJECTIVES: This study was done to assess the impact of anterior mitral leaflet reconstructive procedures on initial and long-term results of mitral valve repair. BACKGROUND: It has been suggested that involvement of the anterior leaflet in mitral valve disease adversely affects the long-term outcome of mitral valve repair. Our policy has been to aggressively repair such anterior leaflets with procedures that include triangular resections in some cases. METHODS: From June 1979 through June 1993, 558 consecutive Carpentier-type mitral valve repairs were performed. The anterior mitral leaflet and chordae tendineae were repaired in 156 patients (mean age 58 years). The procedures included anterior chordal shortening in 78 patients (50%), anterior leaflet resections in 44 (28%), resuspension of the anterior leaflet to secondary chordae in 42 (27%) and anterior chordal transposition in 27 (17%). Concomitant cardiac surgical procedures were performed in 75 patients (48%). RESULTS: The operative mortality rate was 2.5% (2 of 81) for isolated mitral valve anterior leaflet repair and 3.8% (6 of 156) for all mitral valve anterior leaflet repair. Freedom from reoperation at 5 and 10 years was, respectively, 89.7% (n = 160) and 83.4% (n = 24) for the entire series of 558 patients, 91.9% (n = 51) and 81.2% (n = 10) for patients with anterior leaflet procedures, 88.8% (n = 109) and 84.4% (n = 14) for patients without anterior leaflet procedures and 91.7% (n = 118) and 88.9% (n = 18) for patients without rheumatic disease. Logistic regression showed that rheumatic origin of disease (odds ratio 2.99), but not anterior leaflet repair, increased the risk for reoperation. CONCLUSIONS: These results demonstrate that expansion of mitral valve techniques to include anterior leaflet disease yields immediate and long-term results equal to those seen in patients with posterior leaflet disease.

Multiple valve operation for advanced valvular heart disease: results and risk factors in 513 patients.

To assess the results and incremental risk factors affecting outcome after multiple-valve operation in the early blood cardioplegia era of cardiac surgery, follow-up data (mean +/- SD 3.1 +/- 2 years) were obtained on 97% of 513 patients (mean age +/- SD 58.8 +/- 10.5 years) who underwent a multiple-valve procedure between June 1976 and August 1985. Preoperatively 41% of patients were in New York Heart Association functional class III and 54% in class IV. Three groups accounted for 98.6% of the patients: 57.7% had an aortic and mitral valve procedure, 29% had a mitral and tricuspid valve procedure and 11.9% had a triple-valve procedure. The overall hospital mortality rate was 12.5% and overall 5-year survival rate was 67.1%. Hazard function analysis for all deaths revealed systolic pulmonary artery pressure (p less than 0.0001), age (p = 0.005), triple valve procedure (p less than 0.005), concomitant coronary bypass operation (p less than 0.005) and prior cardiac surgery (p less than 0.002) as the significant incremental risk factors predicting decreased survival in the early hazard phase; diabetes (p less than 0.005) predicted decreased survival in the late hazard phase. Postoperatively the condition of 80% of the patients improved to functional class I or II; only 0.6% remained in functional class IV. The 5-year rate of freedom from late combined valve-related morbidity was 81.7% and that of freedom from late combined valve-related morbidity and mortality was 71.7%. These results demonstrate excellent clinical improvement and late survival after multiple valve operation in patients with advanced valvular heart disease, justifying aggressive surgical therapy in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic valve replacement for aortic stenosis in persons aged 80 years and over.

Seventy-one patients aged greater than or equal to 80 years (mean +/- standard deviation 82 +/- 2) with aortic stenosis or mixed stenosis and regurgitation underwent aortic valve replacement alone (n = 35, group 1) or in combination with a coronary artery bypass procedure without any other valve procedure (n = 36, group 2). Preoperatively, 91% had severe cardiac limitations (New York Heart Association class III or IV). Hospital mortality was 12.7% overall (9 of 71), 5.7% (2 of 35) for group 1 and 19.4% (7 of 36) for group 2. Perioperatively, 1 patient (1.4%) had a stroke. Survival from late cardiac death at 1 and 3 years was 98.2 and 95.5%, respectively, for all patients, 100% for patients who underwent isolated aortic valve replacement, and 96.3 and 91.2%, respectively, for patients who underwent aortic valve replacement plus coronary artery bypass. Eighty-three percent of surviving patients had marked symptomatic improvement. Freedom from all valve-related complications (thromboembolism, anticoagulant, endocarditis, reoperation or prosthetic failure) was 93.3 and 80.4% at 1 and 3 years, respectively. Thus, short- and long-term morbidity and mortality after aortic valve replacement for aortic stenosis in patients aged greater than or equal to 80 years are encouragingly low, although the addition of coronary artery bypass grafting increases short- and long-term mortality.

Utility of transesophageal echocardiography during port-access minimally invasive cardiac surgery.

In this study, we sought to determine the use of transesophageal echocardiography (TEE) as the primary imaging technique to assist in the placement of endovascular catheters during minimally invasive, port-access cardiac surgery. The recent development of endovascular catheters that are placed via the femoral artery and vein has enabled patients to be placed on cardiopulmonary bypass without the need for direct visualization of the heart or great vessels via sternotomy. This has allowed cardiac surgery to be performed through smaller thoracotomy incisions. Placement of these catheters has previously been performed with fluoroscopic guidance, which has major imaging limitations. Thirty-six patients underwent port-access cardiac surgery at our institution during the study period. All patients underwent intraoperative TEE. We used TEE to visualize the coronary sinus os, right atrium and superior vena cava, and thoracic aorta to assist with placement of the coronary sinus catheter, venous cannula, and endoaortic clamp. Twenty patients underwent mitral valve surgery, 14 patients coronary artery bypass grafting, 1 patient aortic valve replacement, and 1 patient repair of an atrial septal defect by the port-access approach. TEE was able to adequately visualize the cardiac structures and assist in the placement of the endovascular catheters in all patients. Fluoroscopy was only helpful as an aid to TEE for placement of the coronary sinus catheter. TEE is an excellent imaging modality for the proper placement of these new endovascular catheters, obviating the need for fluoroscopy, except to be on standby and for placement of the coronary sinus catheter.

Aneurysms of the descending aorta. Surgical experience in 48 patients.

Uniformity of opinion does not exist concerning an optimal surgical strategy for descending aortic aneurysms. In order to assess the impact of surgical technique on operative mortality, morbidity, late outcome, we reviewed 48 consecutive patients operated upon from 1976 to 1980. Average age was 61 years, and 37 patients (77%) were men. The average interval of aortic occlusion in the Gott shunt group was 48 minutes, which was significantly longer than that of patients operated upon without shunts (30 minutes). No patient in the Gott shunt group had postoperative paraplegia, but it was noted in two patients (18%) treated without a shunt. Operative deaths in patients with Gott shunts were caused by cardiac (two patients), neurologic (one patient), pulmonary (one patient), and abdominal (two patients) factors. A pulmonary embolus caused the single postoperative death in the "no shunt" group, and another patient died intraoperatively. A group of seven patients were treated by temporary femoral vein--femoral artery bypass because of extensive aneurysmal disease, advanced associated major systemic disorders, or anticipated excessive hemorrhage when the aneurysm was opened. All patients survived free of neurologic sequela, but one developed a reversible intraoperative coagulopathy. This study underscores the safety and usefulness of the femoral vein--femoral artery bypass in treating certain descending thoracic aneurysms and reinforces the importance of several technical guidelines concerning the proper insertion and use of the Gott shunt. These guidelines would have significantly reduced the observed operative morbidity and mortality.

Aneurysms of the ascending aorta and transverse arch: surgical experience in 80 patients.

Aneurysms of the ascending aorta and transverse arch constitute formidable surgical challenges. To assess the impact of surgical techniques on operative morbidity and mortality and late results, we reviewed 80 consecutive patients operated from 1976 through 1980. Average age was 52 years and 81% were male. The operative mortality was 17.5% (14 deaths). In patients with aneurysm of the ascending aorta, operative deaths were due to cardiac factors (three patients), neurologic factors (three patients), cardiac factors (two patients), and exsanguination (one patient) accounted for the six operative deaths in patients with transverse arch aneurysms. Two late neurologic deaths occurred in this group. The following conclusions were reached when the surgical techniques were reviewed: Annuloaortic ectasia is best treated by insertion of a conduit with reimplantation of coronary ostia. Dissections are optimally managed by Dacron graft insertion in the ascending aorta and valve replacement. Aortic valve resuspension was done in six patients, with three undergoing subsequent aortic valve replacement for insufficiency. Aneurysms of the transverse arch treated with profound hypothermia and circulatory arrest were associated with fewer neurologic complications, and the operations were more expeditiously completed. Eleven of 80 patients (14%) had or subsequently needed additional surgical procedures on the aortic valve (insufficiency) or the distal aorta.

Experiences with the Carpentier techniques of mitral valve reconstruction in 103 patients (1980-1985).

A total of 103 patients, age range 2 to 77 years, had some type of Carpentier reconstruction for mitral insufficiency. The mitral insufficiency resulted from ruptured chordae in 52, prolapse in 13, rheumatic fever in 16, coronary disease in eight, congenital disease in nine, and endocarditis in five. Multiple abnormalities were usually present. Four patients had severe calcification of the anulus. A reconstruction was accomplished in almost all patients. A ring annuloplasty was performed in all but two small children, but annuloplasty alone was adequate in only 17 patients. Fifty-eight had resection of 1 to 4 cm of diseased mitral leaflet. In 23 patients, chordal transposition or shortening was employed. Aortic leaflet repair was done in 28. Shortened, fused chordae (one to eight) were divided in 13 patients. Additional procedures performed in 28 patients included coronary bypass in 14. A successful repair was accomplished in all but one patient (moderate residual insufficiency). Two late hospital deaths were unrelated to the mitral repair. Following hospital discharge, ring dehiscence necessitated repeat operation in one patient. Thromboembolism produced a permanent minor neurological deficit in only one patient. There have been no late recurrences of insufficiency. Recurrent endocarditis necessitated valve replacement in three patients. A late Doppler evaluation of 95 patients for mitral insufficiency revealed none in 82, a trace in 12, and moderate insufficiency in one. Late catheterization in 16 patients revealed no insufficiency. The data suggest that reconstruction, rather than prosthetic valve replacement, can be successfully performed in over 90% of patients with nonrheumatic, noncalcified mitral valves. A much wider use of the technique seems strongly indicated.

Resuscitative retrograde blood cardioplegia. Are amino acids or continuous warm techniques necessary?

This experiment was designed to determine the relative degree of cardiac functional recovery provided by various forms of resuscitative retrograde blood cardioplegia after global ischemic injury. Twenty-four dogs were subjected to 20 minutes of normothermic global myocardial ischemia followed by 60 minutes of cardioplegic arrest by one of three methods: group 1, standard cold blood cardioplegia with a cold terminal dose (n = 8); group 2, aspartate-glutamate-enhanced blood cardioplegia with warm induction and terminal enhancement (n = 8); and group 3, continuous warm blood cardioplegia (n = 8). Sonomicrometry was used to analyze left ventricular function for maximal elastance and preload recruitable stroke work area. Data were recorded at baseline and after 30 and 60 minutes of unloaded reperfusion. The results showed improved early recovery of preload recruitable stroke work area, but not of maximal elastance, after reperfusion of ischemic hearts with warm resuscitative blood cardioplegic solution enhanced with amino acids. The functional improvement provided by this technique was transient, however, and no significant differences were detectable among the groups after 60 minutes of unloaded reperfusion. Neither amino acid enhancement nor continuous warm cardioplegia offered a significant advantage in functional recovery over the standard method of cold blood cardioplegia reperfusion.

Biventricular distribution of cold blood cardioplegic solution administered by different retrograde techniques.

Although retrograde cardioplegia has been shown to provide adequate overall protection to the myocardium, delivery of cardioplegic solution to the right ventricle and septum is poor. We used an animal model of occlusion of the left anterior descending coronary artery to study the effects of modifying the conditions of retrograde cardioplegia administration on delivery to the right and left ventricles. Adult mongrel dogs (n = 12) were each given five retrograde injections of microsphere-labeled cardioplegic solution at 10-minute intervals. Four injections were made directly into the coronary sinus with ostial balloon occlusion at the following dosages and pressures: (1) 10 ml/kg at 30 mm Hg, (2) 20 ml/kg at 30 mm Hg, (3) 10 ml/kg at 50 mmHg, and (4) 20 ml/kg at 50 mm Hg. A fifth dose (20 ml/kg) was given directly into the right atrium at 50 mm Hg. Delivery of cardioplegic solution to the left and right ventricles was significantly reduced when the right atrial route was compared with the coronary sinus route at the same dosage and pressure (for left ventricle, 6.0% +/- 1.4% versus 22.7% +/- 11.4%/100 gm, p less than 0.001; for right ventricle, 0.7% +/- 0.2% versus 4.1% +/- 0.4%/100 gm, p less than 0.001). Septal delivery was less than that to the anterior and posterior left ventricle (10.4% +/- 1.3% versus 30.3% +/- 3.9% and 27.9% +/- 3.1%/100 gm, p less than 0.0001) for all injections. Delivery to the body of the right ventricle was less than that to the inflow and outflow tracts (1.8% +/- 0.2% versus 4.5% +/- 0.7% and 8.4% +/- 1.5%/100 gm, p less than 0.0001). These results indicate that, in this model, (1) the right atrial route provides less overall cardioplegic solution to both ventricles than direct retrograde coronary sinus cardioplegia and (2) regional abnormalities in distribution with direct retrograde coronary sinus cardioplegia are not affected by changes in the dosage or pressure of injection.

Role of amino acids and enhancement cardioplegia in routine myocardial protection. Experimental results.

The purpose of this study was to determine the effects of the addition of amino acids to blood cardioplegic solution and the value of terminal cardioplegia enhancement techniques in routine myocardial protection. Forty-five open-chest adult dogs were instrumented with sonomicrometry crystals to measure left ventricular long axis, midequatorial short axis, and wall thickness. The aorta was clamped for 120 minutes of cardiopulmonary bypass. Animals were randomly separated into four myocardial protection groups: (1) blood cardioplegic solution with amino acids and no terminal cardioplegia (n = 12); (2) blood cardioplegic solution with amino acids and warm amino acid terminal cardioplegia (n = 11); (3) blood cardioplegic solution with amino acids and cold amino acid terminal cardioplegia (n = 12); and (4) blood cardioplegic solution plus cold terminal cardioplegia (no amino acids, n = 10). Data for preload recruitable stroke work were obtained by inflow occlusion before bypass (baseline) and at 30 and 60 minutes after reperfusion and analyzed for changes in x-intercept and slope. A significant rightward shift in x-intercept did not occur in any group. When cardiac function was expressed as a percentage of baseline preload recruitable stroke work slope, improved functional recovery was seen at both 30 and 60 minutes in groups 2 (88.6% and 91.8%), 3 (85.8% and 86.9%), and 4 (88.6% and 92.6%) compared with group 1 (77.3% and 79.2%, p < 0.05). No significant difference was found in the degree of functional recovery among groups 2, 3, and 4. These results suggest that for myocardial protection of 2 hours in nonischemic hearts, a terminal dose of blood cardioplegic solution before unclamping is beneficial, but this positive effect is independent of amino acid supplementation and temperature.

Experience with twenty-eight cases of systolic anterior motion after mitral valve reconstruction by the Carpentier technique.

Systolic anterior motion of the mitral valve with left ventricular outflow tract obstruction after Carpentier-type mitral reconstruction with ring annuloplasty has led some surgeons to abandon an otherwise successful repair or to avoid use of a rigid ring. To assess the long-term significance of such motion, we studied 439 patients undergoing Carpenter mitral reconstruction at our institution between March 1981 and June 1990. The hospital mortality rate was 4.8% (21/439) overall and 3.7% (9/243) for isolated mitral reconstruction. Systolic anterior motion was found in 6.4% (28/438) after the operation, and 2.3% (10/438) had a coexisting left ventricular outflow tract gradient (mean 53 mm Hg). Of the 28 patients with systolic anterior motion, 27 (96.4%) had leaflet prolapse, 17 (60.7%) had undergone more than a 3 cm resection of the posterior leaflet, and two (7.1%) had preexisting idiopathic hypertrophic subaortic stenosis. All patients were treated medically, 14 with negative inotropic agents. Follow-up echocardiograms at a mean of 32 months demonstrated the disappearance of systolic anterior motion in 13 of 28 patients (46.4%) and resolution of the outflow tract gradient in 10 of 10 (100%). At follow-up only one patient was in New York Heart Association class III or IV and required reoperation for rheumatic mitral insufficiency. These data demonstrate that systolic anterior motion after Carpentier mitral reconstruction with ring annuloplasty is not prevalent and should be managed medically in most cases. Associated left ventricular outflow tract obstruction resolves with medical treatment.

The effects of different techniques of internal mammary artery harvesting on sternal blood flow.

We investigated chest wall blood flow in a canine model to determine if the technique used to harvest the mammary artery has a differential effect on residual chest wall blood flow. Eight dogs underwent bilateral internal mammary artery mobilization; one artery was harvested as a pedicle and the other was harvested as a skeletonized vessel. Residual blood flow to the chest wall distribution of each artery was measured with radioactive microspheres. Chest wall blood flow was significantly decreased from preharvest levels after internal mammary artery mobilization regardless of the technique used. Tissue blood flows decreased to 46.9%, 22.1%, and 41.2% of baseline values for the manubrium (p < 0.01), sternum (p < 0.001), and ribs (p < 0.05), respectively. Residual sternal blood flow on the side of the skeletonized vessel was significantly greater than on the side of the pedicle graft (2.60 +/- 0.68 versus 1.27 +/- 0.27 cm3/min/100 gm, p < 0.001). We conclude that minimization of tissue mobilization during internal mammary artery harvesting may reduce sternal devascularization. This finding may have clinical significance with respect to lowering the incidence of sternal wound complications in coronary bypass surgery using the internal mammary artery as a bypass conduit.

Single and multivessel port-access coronary artery bypass grafting with cardioplegic arrest: technique and reproducibility.

OBJECTIVES: Although minimally invasive coronary artery bypass grafting is now feasible, using this technique to perform anastomoses on the beating or fibrillating heart may yield poorer graft patency than the standard open techniques that use cardioplegic arrest. This study tested the feasibility and anastomotic reproducibility of minimally invasive coronary bypass using newly developed port-access coronary artery bypass technology (Heartport, Inc., Redwood City, Calif.), which allows endovascular cardiopulmonary bypass, cardiac venting, aortic occlusion, and cardioplegic arrest for internal thoracic artery-coronary artery anastomoses. METHODS: Nineteen dogs had thoracoscopic takedown of either single (n = 14) or bilateral (n = 5) internal thoracic arteries followed by minimally invasive coronary bypass with cardioplegic arrest, done by means of the port-access system. The anastomotic technique was modified after the fourth animal by switching from a microscope to a 2.5 cm oval port and performing a conventional anastomosis with operative loupes. The adequacy of delivery of cardioplegic solution, ventricular decompression, and anastomotic patency was assessed. RESULTS: The crossclamp and bypass times were 50 +/- 15 minutes and 87 +/- 28 minutes (mean +/- standard deviation), respectively. The mean myocardial temperature after cardioplegia was 17 degrees +/- 1 degree C and the aortic pressure (-3 +/- 9 mm Hg) and pulmonary artery pressure (4 +/- 1 mm Hg) were low throughout the procedure. All animals were weaned from bypass without inotropic agents. Angiograms and autopsies demonstrated successful thoracic artery takedown and anastomotic patency in 18 of 19 animals, with 100% anastomotic patency after the technique had been modified after the fourth animal. CONCLUSION: This study describes a reproducible technique for minimally invasive coronary bypass that allows myocardial protection, anastomotic precision, and predictable thoracic artery graft patency. Clinical trials are indicated.

Late functional and hemodynamic status of surviving patients following insertion of the left heart assist device.

Since July, 1978, we have inserted a roller pump type of left heart assist device between the left atrium and ascending aorta in 35 patients. There were no significant complications related to use of the device. Seventeen patients recovered sufficiently to have the device removed. There were four early deaths, 60 to 120 days following removal of the device. Three of these patients died of septic complications and one patient died as a result of a cardiac arrest. Of the 13 long-term survivors, seven are working and six are retired. Five patients have mild to moderate cardiac symptoms, whereas eight others are completely asymptomatic. In three patients the ejection fraction was significantly lower than preoperatively; however, in all other patients the ejection fraction either stayed the same or improved postoperatively. We conclude that this type of left heart assist device can provide adequate cardiac support in patients with profound left ventricular dysfunction following cardiac operations. Furthermore, surviving patients generally have satisfactory long-term cardiac function and are leading productive lives.

The role of the activated clotting time in heparin administration and neutralization for cardiopulmonary bypass.

Precise guidelines for heparin administration and neutralization during cardiopulmonary bypass (CPB) are not established. To a large extent, the uncertainty originates from a disparity between the heparin dosage, the plasma heparin concentration, and the clinical heparin effect. We investigated these relationships in 44 consecutive patients at New York University Medical Center. Following serial loading doses of heparin (2 and 4 mg/kg) there was a wide variation in both the measured clinical heparin effect (activated clotting time--ACT) and the plasma heparin concentration. When the Act was compared to the heparin concentration, there was no linear relationship noted after heparin does commonly employed for CPB. The calculated heparin sensitivity varied over a fourfold range and was not related to the baseline antithrombin III activity. At the completion of CPB, heparin was neutralized with a 2 mg/kg protamine dose regardless of the total heparin dose. Heparin levels fell from 4.17 +/- 1.29 to 0.19 +/- 0.20 units/ml. Additional protamine was given to 49% of the patients as the ACT had not returned to pre-heparin levels. The total protamine dose rarely exceeded 3 mg/kg. This technique resulted in the administration of 30% to 50% less protamine than predicted by other commonly used protocols. In the subsequent 4 hours after protamine administration, heparin levels remained insignificant. Mild heparin rebound was found in two patients (4.5%) but was not associated with excessive bleeding. Following bypass a comparison of heparin levels and ACTs demonstrated the ACT to be a poor indicator of residual circulating heparin. These data show: (1) that neither the heparin dosage nor the plasma heparin concentration can accurately predict the magnitude of the clinical heparin effect in patients undergoing CPB and emphasize the importance of the ACT as the best available measurement of safe anticoagulation, (2) heparin "rebound" was not clinically significant, and (3) heparin was neutralized with 2 to 3 mg/kg protamine in virtually all patients, regardless of the total heparin dose.

Long-term survival with partial left heart bypass following perioperative myocardial infarction and shock.

During the period from July 1, 1978 to Dec. 31, 1980, we employed a partial left heart bypass (left atrium to ascending aorta) in 16 patients who could not be weaned from cardiopulmonary bypass with inotropic agents and the intra-aortic balloon pump. Flow rates up to 3,500 ml/min could be obtained with this device. Eight of the 16 patients survived and left the hospital. One patient died of a cardiac arrest 4 months postoperatively and one has recurrent angina and moderate congestive heart failure 24 months postoperatively. Six patients are well 5 to 17 months after discharge. Seven of the eight deaths were characterized by progressive myocardial failure. One patient died of ventricular fibrillation 18 hours after discontinuation of the left heart bypass. All survivors had significant improvement in ventricular function 12 to 24 hours afer institution of the left heart bypass, which was continued for 16 to 68 hours. These results indicate that early institution of left heart bypass in seriously ill patients can provide satisfactory long-term results.

Adjunctive left ventricular unloading during myocardial reperfusion plays a major role in minimizing myocardial infarct size.

Although prompt institution of reperfusion following coronary artery occlusion has been shown to limit myocardial infarct size, significant "reperfusion injury" may result. We investigated in a canine model whether maintenance of the left ventricle in an unloaded state during the initial reperfusion period following acute myocardial ischemia would result in greater limitation of infarct size or modify the development of reperfusion injury. Group I (control, n = 6) underwent 6 hours of occlusion of the left anterior descending coronary artery without further intervention. In both Group II (n = 6) and Group III (n = 6), the snare was released after 2 hours and hearts were reperfused for 4 hours. In Group III only, the left ventricle was maintained in an unloaded state throughout the entire reperfusion interval via pulsatile left atrial-femoral artery bypass. The results showed that reperfusion of the left ventricle in an unloaded state resulted in significantly improved limitation of both infarct size (area of infarct/area at risk = 16.6% for Group III versus 72.0% for Group I and 55.4% for Group II, p less than 0.001) and area of microvascular damage (area of microvascular damage/area at risk = 4.8% for Group III versus 30.6% for Group II, p less than 0.001). These results indicate that although myocardial reperfusion of the type provided by thrombolysis and/or angioplasty techniques does result in limitation of infarct size when compared to no reperfusion, this limitation is not optimal unless the left ventricle is unloaded during the initial reperfusion period.

Assisted venous drainage presents the risk of undetected air microembolism.

OBJECTIVES: The proliferation of minimally invasive cardiac surgery has increased dependence on augmented venous return techniques for cardiopulmonary bypass. Such augmented techniques have the potential to introduce venous air emboli, which can pass to the patient. We examined the potential for the transmission of air emboli with different augmented venous return techniques. METHODS: In vitro bypass systems with augmented venous drainage were created with either kinetically augmented or vacuum-augmented venous return. Roller or centrifugal pumps were used for arterial perfusion in combination with a hollow fiber oxygenator and a 40-micrometer arterial filter. Air was introduced into the venous line via an open 25-gauge needle. Test conditions involved varying the amount of negative venous pressure, the augmented venous return technique, and the arterial pump type. Measurements were recorded at the following sites: pre-arterial pump, post-arterial pump, post-oxygenator, and patient side. RESULTS: Kinetically augmented venous return quickly filled the centrifugal venous pump with macrobubbles requiring continuous manual clearing; a steady state to test for air embolism could not be achieved. Vacuum-augmented venous return handled the air leakage satisfactorily and microbubbles per minute were measured. Higher vacuum pressures resulted in delivery of significantly more microbubbles to the "patient" (P <.001). The use of an arterial centrifugal pump was associated with fewer microbubbles (P =.02). CONCLUSIONS: Some augmented venous return configurations permit a significant quantity of microbubbles to reach the patient despite filtration. A centrifugal pump has air-handling disadvantages when used for kinetic venous drainage, but when used as an arterial pump in combination with vacuum-assisted venous drainage it aids in clearing air emboli.

Surgical repair of type A aortic dissection by the circulatory arrest-graft inclusion technique in sixty-six patients.

During an 8-year period (1984 to 1991) 66 patients (mean age 59 years, range 26 to 84 years) with type A aortic dissection (60 ascending aorta tears, 6 arch tears; 35 acute, 31 chronic) had surgical repair by a continuous suture-graft inclusion technique. Hypothermic circulatory arrest (16 degrees C) was used in 58 patients (35/35 acute, 23/31 chronic; mean arrest time 26 minutes, range 10 to 55 minutes). Fifty-two patients had hemiarch repair and 6 had total arch replacement. Aortic valve disease necessitated treatment in 38 patients (1 valved conduit, 20 valve replacements, 17 valve repairs). Recently 11 patients had valve repair by reconstruction of the native aortic root, by means of techniques similar to those used for homograft valve insertion. Operative mortality was 9% (14% acute, 3% chronic). Stroke occurred in 2 patients (3%) and was fatal in both. Variables suggestive of increased operative risk by univariate analysis were acuteness (p = 0.12), visceral ischemia (p = 0.12), and preoperative shock (p = 0.13). No variable was significant by multivariate analysis. Overall actuarial survival at 48 months was 77%, with 3 late deaths from a ruptured distal aneurysm. Late computed tomography or magnetic resonance imaging scan was done in 28 patients at a mean interval of 33 months. These studies identified 1 patient with a pseudoaneurysm requiring reoperation and 3 patients with contained flow between the graft and the wrap. Three patients required late operation: 1 for pseudoaneurysm, 1 for arch dissection, and 1 for repair of a distal aneurysm.