Acute hemodynamic benefit of multisite ventricular pacing after congenital heart surgery

BACKGROUND: Cardiac dysfunction after congenital heart surgery is a major cause of morbidity and mortality. Cardiac resynchronization through multisite ventricular pacing (MSVP) improves cardiac index and ventricular function, and lowers systemic vascular resistance (SVR) in adults with heart failure and interventricular conduction delay. METHODS: The acute hemodynamic effects of MSVP after congenital heart surgery were assessed. Twenty-nine patients (aged 1 week to 17 years) with prolonged QRS interval had atrial and ventricular unipolar epicardial temporary pacing leads placed at surgery. Group 1 consisted of patients with a single ventricle (n = 14); group 2 included patients with two-ventricle anatomy (tetralogy of Fallot, ventricular septal defect) undergoing ventricular surgery (n = 10); and group 3 included patients with two-ventricle anatomy undergoing other cardiac surgery (n = 5). At a mean postoperative day 1 (range, 0 to 6), blood pressure, systemic and mixed venous oxygen saturations, electrocardiograms, and echocardiograms were obtained before and after 20 minutes of MSVP. RESULTS: The QRS duration decreased with MSVP in all patients (mean, 23%, p < 0.005). Systolic blood pressure improved in all patients (mean, 9.7%, p < 0.005). Cardiac index improved in 19 of 21 patients tested, with no change in 2 patients (mean, 15.1%, p = 0.0001). In 2 patients, MSVP facilitated weaning from cardiopulmonary bypass. Echocardiographic mitral or tricuspid valve inflow was not significantly different with MSVP. CONCLUSIONS: Multisite ventricular pacing results in improved cardiac index and increased systolic blood pressure, and it can also facilitate weaning from cardiopulmonary bypass. Multisite ventricular pacing may be used as adjunct to standard postoperative treatment of cardiac dysfunction after congenital heart surgery.     

The treatment of intractable supraventricular tachycardia after open heart surgery by a continuous infusion of verapamil and ventricular pacing

Four patients who developed intractable supraventricular tachycardia (SVT) after open heart surgery were treated using a new therapeutic method of creating a pharmacological atrioventricular block by the continuous infusion of verapamil with ventricular pacing. Both the initial dose and the effective dose, being the verapamil dose necessary to maintain pharmacological atrioventricular block to prevent the recurrence of SVT, were surveyed with clinical results. The verapamil-induced hemodynamic changes observed 4 h and 8 b after treatment, as indicated by systolic arterial blood pressure, mean arteral blood pressure, heart rate, cardiac index, and urine volume, were compared with the values I h before treatment. After an initial low dose infusion of 0.07 ± 0.02 mg/kg · h had been given, an effective and safe dose of 0.11 ± 0.05 mg/ g · h was determined. Good hemodynamic and clinical results were achieved in all four patients who are now leading an active life. These results therefore encourage us to apply this therapeutic method for treating patients with intractable and recurrent SVT after open heart surgery.     

Atrial tachyarrhythmias and permanent pacing after pediatric heart transplantation.

BACKGROUND: Atrial tachyarrhythmias have been reported in as high as 50% of adult heart recipients. Limited information is available on arrhythmias in pediatric transplant patients. Our objective was to determine the prevalence and significance of atrial tachyarrhythmias and permanent pacing following pediatric heart transplantation. METHODS: A retrospective review of the medical records, electrocardiograms, and Holter recordings of all consecutive patients following heart transplantation at Children's Hospital, Boston (n = 104) and Lucile Packard Children's Hospital, Stanford (n = 123) was performed. The study group consisted of 227 patients with a median age at transplant of 10.2 yrs (1 day-23.3 yrs). RESULTS: Atrial tachyarrhythmias occurred in 32 patients (14%) at a median of 15 days post-transplant (1 day-9.2 yrs) and included atrial flutter (n = 13), atrial fibrillation (n = 7), ectopic atrial tachycardia (n = 5), atrioventricular reciprocating tachycardia or atrioventricular node reentry (n = 5), and other (n = 2). Atrial flutter was the only tachyarrhythmia associated with allograft rejection (6/13 atrial flutter vs. 0/7 atrial fibrillation vs. 0/5 ectopic atrial tachycardia, p = 0.03). Patients with atrial fibrillation had a 2.5 fold (95%CI 1.7-3.5) higher risk of death or retransplant compared to patients without atrial fibrillation. Ectopic atrial tachycardia tended to occur in younger recipients compared to atrial fibrillation and flutter (2.7 yrs vs 18.6 yrs and 8.5 yrs respectively, p = 0.06) and was associated with a benign clinical course. There was no association between atrial tachyarrhythmias and graft ischemic time, surgical technique, or coronary artery disease. Pacemakers were required in 12 patients (5.2%), 7 with sinus node dysfunction and 5 for intermittent complete atrioventricular block. There was no consistent association between the need for permanent pacing and coronary artery disease, rejection, or surgical technique. CONCLUSIONS: Atrial tachyarrhythmias and permanent pacing were uncommon in this cohort of pediatric heart transplant recipients. Association with cardiac rejection, clinical course, and mortality varied depending on the tachyarrhythmia mechanism.     

Mediastinal infection after open heart surgery

Mediastinal infection occurred in 29 of 2031 patients (1.4%) who underwent median sternotomy for cardiac operation at the National Heart, Lung and Blood Institute between 1956 and 1981. Factors associated with the development of mediastinitis included postoperative complications such as low cardiac output, respiratory insufficiency, reoperation for bleeding, repeat median sternotomy, and triple valve replacement. Factors that were not significantly associated with the development of mediastinitis included preoperative functional class, preoperative cardiac index, age, sex, weight, or presence of diabetes mellitus. The mortality rate in patients who developed mediastinitis was 52%. Factors associated with death included preoperative functional class III or IV, type of operation, type of organism involved, and the development of pneumonia. The mortality rate was significantly lower (35% versus 73%) in the patients who underwent mediastinal exploration for treatment. There was no difference in survival whether the wound was closed over drainage tubes or packed open. Hospital stay, however, was significantly prolonged in the patients whose wounds were packed open.     

Tubular dysfunction after open heart surgery

beta 2-microglobulin (BMG) and conventional renal function parameters (creatinine clearance (C-cr) etc.) were measured in 36 adult patients before and after open heart surgery (Group-2). Same study was performed in 14 adult patients abdominal surgery (Group-1). Urinary BMG concentration (U-BMG) increased remarkably in both groups immediately after surgery. U-BMG returned to the preoperative level on the 4th postoperative day (4-POD) in Group-1, and 7-POD in Group-2. The degree of increase in Group-2 was remarkable comparing with that in Group-1. The tubular dysfunction after surgery was believed to result in a marked rise in U-BMG, therefore, the later recovery and higher increase of U-BMG in Group-2 indicated that the tubular dysfunction after open heart surgery was severer comparing with that after abdominal surgery. On 7-POD, in Group-2, U-BMG was still abnormal in 13 cases, which suggested the prolonged tubular dysfunction after open heart surgery. A retrospective study to determine the risk factors of prolonged tubular dysfunction was performed in 34 patients in Group-2. Significant risk factors were preoperative blood urea nitrogen and urine osmolarity. Several factors were not significant including perfusion time, aortic alamp time, preoperative C-cr, U-BMG, serum creatinine concentration and free water clearance.     

Wound infections after open heart surgery

One-hundred and fifty patients undergoing open heart surgery were investigated for development of postoperative wound infections. These patients underwent midline sternotmy for various procedures like coronary artery bypass, valve replacements and repair of congenital defects. Sternal wound infections developed in 14 (9.3%) patients. Two patients of coronary bypass developed leg wound infections. Possible risk factors were evaluated by univariate analysis. Results indicated that length of stay in the ICU, re-exploration/resuturing and prolonged use of intravascular and urinary catheters and chest tubes were significantly associated with increased risk of wound infection (p value < 0.05).     

Clinical experience of mechanical ventricular support with centrifugal pump for severe ventricular failure after open heart surgery

Five adult patients (pts) with age 15-67 (mean 43) received mechanical circulatory support with centrifugal pump (Biomedicus, BP-80, Sarns centrifugal pump) for postcardiotomy profound shock. Three pts underwent left ventricular support (LVS) alone, and the other 2 required biventricular support (BVS). Duration of the LVS ranged from 33 to 240 hours (mean 126 hours) and the right ventricular support 92, 120 hrs. Pump flow rate was 1.1 to 2.5 (mean 1.9) L/min/m2. Sixteen pumps were used and the pump exchange was performed 9 times in five pts and an average perfusion time per pump was 57 hrs. Two of 3 pts with LVS alone survived and one died of multiorgan failure associated with right heart dysfunction. In two pts with BVS, one survived and the other died of persistent low cardiac output early after pump removal. As the complication during mechanical support, bleeding was seen in 3 pts and cerebral infarction in one. Although centrifugal pump has potential limitation in antithrombogenicity and durability, this device provides a simple and effective mechanical circulatory support.     

Postoperative nausea and vomiting after open heart surgery

We investigated the incidence of the postoperative nausea and vomiting (PONV) following cardiac surgery with cardiopulmonary bypass. We conducted a prospective study of 65 cases with direct interviews by anesthesiologists who are blind to this protocol every 6 hours during ICU stay. There were no differences in age, body mass index, dose of fentanyl, operating time, cardiopulmonary bypass time and ventilation time in ICU between PONV(+) and PONV(-). Incidence of PONV was 43%, but 70% of female patients complained of PONV. Prophylactic antiemetic strategy might be clinically relevant to female patients who are to undergo open heart surgery with cardiopulmonary bypass.     

Atrial septal dissection late after congenital heart surgery

Atrial septal dissection is a rare entity usually seen after surgical mitral valve repair, myocardial infarction, or endocarditis. This is a report of an atrial dissection in a young girl found on routine follow-up echocardiography after repair of atrial and ventricular septal defects. No identifiable predisposing risk was found prior to or at the time of surgical repair. Considerable risk of significant morbidity and even mortality attends atrial dissection due to the risk of rupture.