Influence of a vital capacity maneuver on pulmonary gas exchange after cardiopulmonary bypass.

OBJECTIVE: To investigate the effect of a single, vital capacity breath (vital capacity maneuver [VCM]), administered at the end of cardiopulmonary bypass (CPB), on pulmonary gas exchange in patients undergoing coronary artery bypass graft surgery. DESIGN: Prospective, randomized, double-blind study. SETTING: University-affiliated hospital. PARTICIPANTS: Forty patients scheduled for elective coronary artery bypass graft surgery and early tracheal extubation. INTERVENTIONS: Patients were randomized to 1 of 2 groups. VCM patients received a VCM at the conclusion of CPB. Control patients received no VCM. MEASUREMENTS AND MAIN RESULTS: Intrapulmonary shunt (Q(S)/Q(T)), arterial oxygenation (PaO2), and alveolar-arterial oxygen gradients (P(A-a)O2) were measured after induction of anesthesia, CPB, intensive care unit (ICU) arrival, and extubation. The duration of postoperative intubation was recorded for each group. Q(S)/Q(T) increased significantly 30 minutes after CPB in the control group (15.7 +/- 1.8% to 27.4 +/- 2.6%; p = 0.01). In the VCM group, a small decrease in Q(S)/Q(T) occurred (16.1 +/- 2.0% to 14.9 +/- 2.0%). After ICU arrival and extubation, no significant difference in Q(S)/Q(T) existed between the 2 groups. With the exception of a higher P(A-a)O2 in the control group at induction of anesthesia, no differences in PaO2 or P(A-a)O2 were present between the 2 groups at any measurement interval. Patients who received a VCM were extubated earlier than the control group (6.5 +/- 2.1 hours v 9.4 +/- 4.2 hours; p = 0.01). CONCLUSION: The use of a VCM prevented an increase in Q(S)/Q(T) from occurring in the operating room. Although a VCM did not influence pulmonary gas exchange in the ICU, its application in the operating room appears to exert a beneficial effect on tracheal extubation times after cardiac surgery.

Evaluation of oxygen extraction ratio as a physiologic transfusion trigger in coronary artery bypass graft surgery patients.

BACKGROUND: Approximately 20 percent of all allogeneic blood transfusions are administered in connection with coronary artery bypass graft (CABG) operations. Transfusion practices vary across the country. The whole-body oxygen extraction ratio (O2 ER) reflects the adequacy of the patient's response to acute normovolemic anemia with an O2 ER of approximately 50 percent being shown to be an appropriate transfusion trigger. The present study monitored the O2 ER in patients undergoing CABG and determined if transfusion practices would have been different if an O2 ER > or = 45 percent were used as a transfusion trigger. STUDY DESIGN AND METHODS: Seventy patients with a postoperative Hct < = 25 percent were the test subjects. Arterial and mixed venous contents were determined before the operation, in the intensive care unit after the operation, and 12 hours after the operation. RESULTS: There were no deaths. Forty-one patients received allogeneic transfusion. These patients were older, weighed less, and had a preoperative Hct lower than the nontransfused patients. There were no significant differences between transfused and nontransfused patients with respect to postoperative Hct (21.0 +/- 0.4 vs. 22.2 +/- 0.4), cardiac index (2.5 +/- 0.1 vs. 2.7 +/- 0.1), O2 delivery (6.4 +/- 0.3 vs. 6.7 +/- 0.3), O2 consumption (2.5 +/- 0.1 vs. 2.5 +/- 0.1), and O2 ER (38.3 +/- 1.7 vs. 37.5 +/- 1.5). In the transfusion group, 7 of 21 patients had a postoperative O2 ER > or = 45 percent, while 3 of 35 in the nontransfused group had that result. CONCLUSION: The use of O2 ER as a transfusion trigger as part of a transfusion algorithm could lead to a reduction in allogeneic blood transfusion.

Multi-site dual surface monophasic action potential mapping of atrial repolarization in vivo: is atrial repolarization a two- or three-dimensional process?

Although the atrial free wall is a thin structure, atrial depolarization has been shown to have aspects of three-dimensionality. This study asks whether the same is true for atrial repolarization. By using a multi-element dual-surface probe, monophasic action potentials (MAPs) were recorded simultaneously at several opposing sites on the right atrial endocardial and epicardial surfaces in six open-chest pigs. The times of depolarization and repolarization were marked in recordings during sinus, paced rhythms, and during infusions of cold saline to the epicardial surface, which generated a temperature gradient across the atrial wall. Repolarization times were similar on endocardial and epicardial surfaces in some sites, but others showed significant differences during sinus and paced rhythms. Cold saline infusion produced a significant lengthening of MAP duration, and this was more pronounced on the atrial endocardial sites than on the epicardial sites. The observed differences in endocardial and epicardial repolarization times may be due to the presence of atrial pectinate muscles on the endocardial surface. These results suggest that in some regions atrial repolarization is a three-dimensional process. Possible limitations of this study include the fact that the depth of view of MAPs recorded from the atrial wall may extend to the opposing surface.

False aneurysm of the right internal mammary artery. Late rupture after sternotomy.

This report describes a late, near-fatal rupture of a false aneurysm of the right internal mammary artery subsequent to coronary artery bypass grafting. The patient presented to us in shock due to hemorrhaging, 8 weeks after bypass surgery that had been complicated by sternal fracture, dehiscence, and infection. Emergent thoracotomy and suture ligation controlled the hemorrhage. To the best of our knowledge, this is the 1st reported case of late massive hemorrhage caused by injury to an internal mammary artery after sternotomy. The literature is reviewed and discussed.

Method for creation of the aortotomy site for saphenous vein grafts.

Saphenous vein coronary artery bypass grafting requires a proximal anastomosis of the vein to the aorta. A variety of techniques have been described to create the aortotomy. We have developed a four-sided knife (Xcision Scalpel; patent pending, Research Medical, Inc, Midvale, UT) that facilitates the creation of a more uniform circular aortotomy. The purpose of this communication is to describe the knife and the technique for its use.

Effect of triiodothyronine on graft function in a model of heart transplantation.

BACKGROUND: Brain death is associated with neuroendocrine changes that result in impaired metabolism, reduced myocardial energy stores, and deteriorating cardiac function. As a result of these changes, a substantial number of normal human hearts are not considered suitable for transplantation. In the hope of preventing these complications and stabilizing the condition of cardiac donors, we compared the function of transplanted hearts from brain-dead rats that received triiodothyronine (T3) (n = 6) with that of hearts from a group that received a placebo (n = 5). METHODS: This experiment was designed to be both blinded and randomized. Brain death was achieved by bilateral carotid ligation and inflation of an intracranial balloon. Triiodothyronine or placebo was administered in a blinded, randomized fashion. The brain-dead donors were then supported with conventional techniques for 2 hours after which time heterotopic transplantation was performed using hypothermic preservation and a working heart model. Hemodynamics of the transplanted hearts were assessed 48 hours postoperatively. RESULTS: The hearts from donors that had been pretreated with T3 were found to have a significantly higher (p < 0.005) peak left ventricular pressure than the hearts from the placebo-treated group (137 +/- 17 mm Hg versus 115 +/- 15 mm Hg). Left ventricular end-diastolic pressure was significantly lower (p < 0.01) in the T3-treated group (5.2 +/- 2.2 mm Hg) compared with the placebo-treated group (6.9 +/- 0.5 mm Hg). There was also a significantly higher (p = 0.03) maximal first derivative of left ventricular pressure in the T3-treated group compared with the placebo-treated group (4,876 +/- 1,348 mm Hg/s versus 3,344 +/- 1,016 mm Hg/s). Finally, the cardiac output in the group given T3 was 93 +/- 16 mL/min compared with 61 +/- 22 mL/min in the group given the placebo (p < 0.01). CONCLUSIONS: Hearts from brain-dead rats that had received T3 before transplantation showed improved postoperative function. The experimental design of predonation brain death, cold immersion storage, and transplantation in a working heart model should make these data more relevant clinically than those previously reported.

Heart transplantation charges: status 1 versus status 2 patients.

BACKGROUND: The current health care environment mandates closer scrutiny of health care dollar allocation. To better understand the distribution of heart transplantation costs, we reviewed hospital and physician billing of patients who underwent orthotopic heart transplantation between August 1988 and September 1993. METHODS: This study is a retrospective review of 107 consecutive cases. Charges and clinical results of United Network for Organ Sharing status 1 patients (n = 46), including 17 bridge to transplantation patients, were compared with those of United Network for Organ Sharing status 2 patients (n = 57). Charges were converted to 1992 dollars. RESULTS: During the first 12 months of the study, 77% of heart transplantations were performed in United Network for Organ Sharing status 2 patients, whereas over the last 12-month period, 25% of the transplantations were performed in status 2 patients. No significant differences were found in age, gender, type of cardiomyopathy, or survival between the status 1 and status 2 groups. The length of hospitalization for the status 1 group ranged from 8 to 138 days (mean 49 days) as opposed to 5 to 82 days (mean 17.5 days) for the status 2 group (p < 0.0001). Pretransplantation hospital charges were significantly higher for the status 1 group ($47,917 to $341,215, mean $109,116) when compared with status 2 ($0 to $10,035, mean $250) (p < 0.0001). No significant difference was found in posttransplantation hospital charges between status 1 ($47,917 to $210,027, mean $95,379) and status 2 patients ($48,093 to $380,745, mean $102,265). Total charges were significantly higher (p < 0.0001) for the status 1 group ($89,910 to $512,331, mean $239,375) when compared with the status 2 group ($63,885 to $455,680, mean $128,594). Total transplantation charges for the study period were $18,341,108. This amount could have paid for 77 status 1 transplantations or 143 status 2 transplantations. CONCLUSIONS: If current trends continue and the donor pool remains the same, most transplant recipients will be status 1, resulting in a comparable number of transplantations performed at twice the charges.

Risk stratification in patients bridged to cardiac transplantation.

Patient selection is considered one of the most important factors influencing success in bridge to transplant procedures. However, to date it has been difficult to identify predictors of mortality in this population using univariate or multivariate analysis. In 1988, we developed a scoring system using 21 clinical variables that could be calculated rapidly at the bedside while evaluating potential candidates. Points were designated to these variables using a scale of 1 to 3, 1 having the least adverse effect on survival and 3 the most. Patients received a value of 0 for each variable that did not apply. This scoring system was used in a retrospective analysis for 15 bridge to transplant patients. The results showed a significant difference (p < 0.003) between the 8 survivors (mean score, 5.75 +/- 2.19) and the 7 nonsurvivors (mean score, 11.71 +/- 3.45). Since 1989, we have prospectively calculated the scores in an additional 27 patients. Based on the score, all 42 patients were divided into three groups: group I had scores of 1 to 5; group II, 6 to 10; and group III, 11 to 16. The mean score for group I (16 patients) was 3.69 +/- 1.25. All group I patients survived. Group II patients (n = 15) had a mean score of 7.87 +/- 1.36 and a survival rate of 53%. The mean score for group III (n = 11) was 13 +/- 1.73. Thirty-six percent of these patients survived. Comparison of survival and mean scores among the three groups was statistically significant (p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Left ventricular cannula obstruction in a patient with previous ventricular aneurysmectomy.

Cannula position is an important factor influencing optimal ventricular assist device function. A case of inflow cannula malposition resulting in suboptimal left ventricular assist device performance is presented. A discussion of alternative techniques and diagnosis is provided.

Noncardiac operations in patients supported with mechanical circulatory support devices.

BACKGROUND: Recent advances in technology as well as refinements of patient selection criteria have improved results of ventricular assistance in patients with end-stage heart disease. With a "normal" cardiac output and the resultant improvement in end-organ perfusion, some patients revert to normal or near normal physiology. Seven patients supported with cardiac assist devices who have undergone general surgical, nonassist device related procedures with the assist device in place are presented. STUDY DESIGN: This is a historical review of seven cases. RESULTS: The surgical procedures included three cholecystectomies, one dialysis catheter placement, and one thoracoscopy. Six patients had Thoratec ventricular assist devices (Thoratec Laboratories Corp., Berkeley, CA) and one was supported with a Jarvik (Symbion, Inc., Tempe, AZ) total artificial heart. In one patient, postcholecystectomy bleeding was the only complication that may have been directly attributable to having an assist device in place. Four patients underwent successful transplantation and three patients died, two during support and one after transplantation. CONCLUSIONS: As heart transplant waiting lists become longer and when permanent ventricular assist devices become available, an increasing number of patients on ventricular assistance will have noncardiac related pathology requiring operative intervention. In our experience, patients supported on mechanical assist devices tolerated these procedures well.

Mechanical circulatory support of the failing heart.

Over the past 30 years, there have been significant pharmacological and technological advances in the treatment of cardiogenic shock. Although most patients who develop cardiogenic shock can be effectively treated with conventional therapy, including inotropic and vasodilating drugs and intra-aortic balloon pumps, a significant number of patients have ventricular failure that is refractory to conventional therapy. For these patients, the prognosis is poor unless the deleterious effects of cardiogenic shock can be reversed. For some, cardiac revascularization or the repair of mechanical defects reverses the hemodynamic deterioration. However, there are subgroups of patients in whom an advanced form of mechanical circulatory support is necessary for myocardial recovery or in whom recovery will never occur, but who may be candidates for cardiac transplantation.

Tricuspid valve replacement after orthotopic heart transplantation.

Atrioventricular valvular regurgitation is a known complication after cardiac transplantation. In this communication, we describe a case of progressively severe tricuspid insufficiency that ultimately necessitated tricuspid valve replacement. The patient has done well clinically since valve replacement, and a postoperative cardiac catheterization demonstrated normal right heart hemodynamics. A discussion of proposed causes and a review of the literature are provided.

Circulatory assist devices in congestive heart failure.

This article discusses the use of mechanical circulatory assist devices to support patients who have developed heart failure that has become refractory to more conventional treatment. Included is a description of the various devices available, the respective advantages and disadvantages of each, and a general discussion of the indications for mechanical circulatory support.