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In an effort to shorten the hospital stay after implantation of a permanent cardiac pacemaker, some physicians have begun performing pacemaker implantation on an ambulatory basis. To assess the potential safety of shortening the duration of hospitalization after pacemaker implantation, we reviewed the complications that occurred in 100 consecutive patients after pacemaker implantation and noted the time after the implantation when the complications occurred. In our study group, all complications that necessitated invasive intervention occurred within 24 hours after the pacemaker implantation. Complications that necessitated noninvasive programming occurred as long as 72 hours after implantation, and all could have been safely corrected at the time of follow-up had the patient been dismissed at the 24-hour period. Although we do not believe that ambulatory pacemaker implantation should be routinely implemented at this time, the practice of dismissing patients at 24 hours after pacemaker implantation and scheduling subsequent outpatient follow-up seems to be safe and effective.

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Tissue-valved prosthetic extracardiac conduits fail in 6% to 30% of patients within 5 years of implantation. Failure is caused both by valve degeneration and by conduit peel formation. This report describes a technique, performed in 16 children, in which an obstructed right ventricle-to-pulmonary artery valved conduit was removed and a new conduit constructed using the conduit bed as the posterior wall and a patch of xenograft pericardium (n = 10), homograft dura mater (n = 5), or Dacron (n = 1) as the roof of the conduit. One child with pulmonary hypertension required a Björk-Shiley pulmonary valve; in the others no valve was inserted. This technique simplifies conduit replacement, allows for a generous-sized outflow tract that may grow with patient growth, and uses material unlikely to become obstructed.

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Spontaneous closure of congenital ventricular septal defect occurs commonly in infants and young adults. Occurrence in adults--patients older than 21 years--however, is rare. For this reason, we report on spontaneous closure of a congenital ventricular septal defect in a patient older than 26 years. This case was documented by catheterization before and after spontaneous closure. They proposed mechanisms of spontaneous closure are briefly reviewed.

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Intra-aortic balloon pump counterpulsation required as an adjunct during weaning from cardiopulmonary bypass or for circulatory support in the immediate postoperative period was analyzed in 2,498 patients undergoing valve replacement between December, 1972, and September, 1981. A total of 140 successful insertions were performed in 155 attempts. Ninety-five of these patients were from a homogeneous cohort of 1,908 patients undergoing valve replacement with porcine xenografts and were analyzed for factors that might be useful predictors of the need for balloon pump support. Univariate analysis of individual factors delineated preoperative characteristics in patients having mitral valve replacement and intraoperative factors in all patients that correlated with use of the balloon pump. Multivariate analysis revealed a subset of male patients with mitral valve and coronary disease most likely to require counterpulsation. Overall survival rate was markedly reduced at 30 days (balloon counterpulsation plus valve replacement, 50% +/- 5%; valve replacement only, 96% +/- 5%; p less than 0.001) and at 1 year (balloon counterpulsation plus valve replacement, 38% +/- 5%; valve replacement only, 89% +/- 1%, p less than 0.001) if balloon pumping was required. The entire group of 140 patients were retrospectively analyzed for factors predictive of survival. Patients requiring balloon pumping who had a preoperative diagnosis of aortic regurgitation had a lower 1 year survival rate (13% +/- 9%) than the total subgroup undergoing balloon counterpulsation (36% +/- 4.0%) (p = 0.002). Similarly patients treated by balloon counterpulsation who had postoperative renal failure had a significantly lower 1 year survival rate (17% +/- 5%) than those without renal failure (66% +/- 6%) (p = 0.003). The survival rate of patients who required this therapeutic modality after valve replacement is poor. Other methods of hemodynamic support are necessary.

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The effect of preserving the heart and lungs with hypothermia and Collins solution was studied in 13 mongrel dogs undergoing combined heart-lung transplantation. The five control animals who underwent an immediate transplant following Collins solution perfusion had small increases in extravascular lung water when measured 2.5 hours posttransplant as seen in a previous study. The eight animals who had hypothermic preservation following Collins solution perfusion had significantly higher extravascular lung water than controls (16.3 +/- 1.8 ml/kg in preserved animals; 11.2 +/- 1.7 ml/kg in controls p less than 0.05). The level of lung water reached at 2.5 hours postoperatively was similar to that reached with a previously reported, unacceptable preservation technique. Survival beyond this point was poor due to severe pulmonary edema. We conclude that the use of this solution, given under the experimental conditions which we describe, is not acceptable for hypothermic preservation of the heart and lungs for combined transplantation.

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Six to thirty percent of right ventricular-to-pulmonary arterial (RV-PA) valved conduits in children fail within 5 years. Experience with correction of tetralogy of Fallot has shown that a competent pulmonary valve is not essential for excellent late results in most patients. Between March 1980 and November 1984, 26 patients who were 12.5 +/- 3.3 years old underwent conduit replacement 6.7 +/- 2.4 years after definitive repair of congenital heart defects in which a xenograft RV-PA valved conduit had been used. A new Dacron tube graft (n = 15) or pericardial (n = 8), dura mater (n = 2), or Dacron patch (n = 1) over the previous conduit bed was used as replacement. Preoperative mean right ventricular systolic pressure was 90.5 +/- 20 mm Hg and mean gradient across the conduit was 67.9 +/- 24.5 mm Hg. After replacement with a nonvalved conduit, right ventricular systolic pressure was reduced to 45.2 +/- 10.8 mm Hg (p less than .001), with a gradient of 8.9 +/- 7.6 mm Hg (p less than .001). There were no operative deaths. Follow-up at 19.5 +/- 14.9 months (range = 0 to 53) showed that all patients were in New York Heart Association class I (n = 21) or class II (n = 5). In the absence of pulmonary hypertension, hypoplastic pulmonary arteries, significant right ventricular dysfunction, or unrepaired tricuspid regurgitation, replacement of an obstructed conduit with a nonvalved conduit gives excellent early results and may diminish the need for late reoperation.

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The presence of unrecognized partial anomalous pulmonary venous connection may cause complications of pulmonary infarction and right-to-left shunting in patients undergoing the modified Fontan procedure. These complications can be prevented by identification of any anomalous pulmonary venous connection at preoperative cardiac catheterization.

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The effect of hypothermic preservation of the heart and lungs with a crystalloid solution was evaluated in 12 mongrel dogs receiving heart-lung allografts. Six animals served as controls and received an immediate heart-lung transplant. Six animals were in the experimental group and received a heart-lung transplant after 5 hours of preservation at 4 degrees C following perfusion of both organs with a crystalloid solution. Physiological function of the heart and lungs was studied for 20 hours after transplantation. While cardiac function was minimally depressed following preservation, pulmonary function testing demonstrated significantly greater increases in extravascular lung water in experimental animals, suggesting that an ischemic lung injury occurred with this preservation technique. The model allows for future evaluation of other methods of combined preservation of both the heart and lungs for transplantation.

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The feasibility of clinical heart-lung transplantation requires a better understanding of the physiological consequences of the operation, heart-lung denervation, and the quality of graft preservation. An acute canine model was used to evaluate heart-lung function during the first 24 hours after transplantation. Measurements of cardiopulmonary dynamics were performed in 5 donor animals and compared sequentially after transplantation in the respective recipients. Orthotopic allotransplantation was performed on cardiopulmonary bypass with moderate hypothermia after perfusion of both the heart and lung with a clinical cardioplegic solution (4 degrees C; potassium chloride, 30 mEq/L; mannitol, 20 gm/L). Postoperatively, the animals were ventilated continuously and anesthetized. Hemodynamic variables were monitored, and measurements were made of arterial and venous oxygen, carbon dioxide, saturation, and pulmonary mechanics. Cardiac output and a derived measurement of lung water were determined. Pulmonary vascular resistance, arteriovenous shunt, resistance, and compliance were calculated. At the termination of the experiment, significant differences were observed between donor and recipient lung-water levels (7.7 +/- 0.9 ml/kg versus 12.0 +/- 3.1 ml/kg, respectively; p less than 0.05); 100% arterial oxygen tension (509 +/- 37 mm/Hg versus 227 +/- 114 mm/Hg, respectively; p less than 0.01); and pulmonary compliance (38 +/- 18 ml/cm H2O versus 11 +/- 4 ml/cm H2O, respectively; p less than 0.05). Arteriovenous shunt increased from 12.2 +/- 4 to 16.5 +/- 5% (p = 0.2). This model evaluates the technique currently employed clinically and will be used in the future to compare methods of heart-lung preservation with the goal of allowing distant heart-lung procurement.

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Although surgeons and anesthesiologists are constantly warned of the danger of hypokalemia following mechanical bowel preparations during the peri- and intraoperative periods, the amount and significance of this problem have not been quantitated. Therefore, the magnitude of the potassium (K+) depletion resulting from three to four days of mechanical bowel preparation was measured in a randomized, prospective fashion in 53 patients. The 27 patients in Group I received intravenous and/or oral potassium chloride supplementation during the preoperative bowel preparation, while the 26 patients in Group II received no supplementation. In an additional five patients, renal and colonic excretory potassium losses were measured to determine if they correlated with preoperative serum potassium levels. All patients had a standard preparation consisting of clear liquid diet (15 mmol K+/day), magnesium citrate orally, enemas, and oral antibiotics. Serum K+ levels in patients in Group I decreased from control levels of 4.01 + 0.41 mmol/1 to 3.71 +/- 0.58 (P less than 0.01) despite an average of 60 mmol potassium chloride supplementation during the preparation. The serum potassium levels in patients in Group II decreased from 4.13 + 0.69 mmol/1 to 3.43 +/- 0.53 (P less than 0.001) during the preparation. Measurement of stool K+ content revealed values that varied considerably between patients and that did not correlate with immediate preoperative serum levels. Urinary K+ measurement showed little renal compensation during the preparation and it did not significantly correlate with preoperative serum levels either.

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During a 7-year period, intraaortic balloon pumping (IABP) was attempted in 319 cardiac surgical patients. The indications for IABP were stringent and consisted of unsuccessful discontinuation of cardiopulmonary bypass (39%), anticipated failure (40%) to wean from cardiopulmonary bypass, postoperative low cardiac output, or intractable ventricular tachyarrhythmias (15%). IABP support was successfully instituted in 280 patients and was unsuccessful in 39 patients ("controls"). These two groups were comparable except for an older mean age and a higher ejection fraction in controls. Operative mortality rates were 45% and 62% for IABP and control groups, respectively (p = 0.077). This difference was most evident in coronary artery bypass patients, in whom the decision to institute IABP counterpulsation was made intraoperatively before attempted discontinuation of cardiopulmonary bypass. Two years postoperatively the actuarial survival rate was 45 +/- 3% for the IABP group and 23 +/- 9% for the control group (p = 0.006). After exclusion of operative deaths, however, these survival rates were 81 +/- 3% and 60 +/- 20%, respectively (p = NS). The average hospital charge incurred by IABP patients was threefold greater than that of uncomplicated cardiac surgical procedures. We conclude that IABP counterpulsation is therapeutic for some cardiac surgical patients, but its benefits cannot be defined easily. The long-term survival rates for patients with advanced disease requiring IABP support perioperatively are poor and warrant continued development of more effective methods of mechanical circulatory assistance and heart replacement.

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