Salvage transvenous rapid atrial pacing to terminate atrial flutter after cardiac operations.

Atrial flutter occurring after cardiac operations normally responds well to atrial overdrive pacing through epicardial atrial pacing wires and medication. When this fails, transvenous atrial overpacing offers an attractive alternative. We performed the procedure 29 times in 25 patients. Sinus rhythm returned acutely after 25 procedures in 21 patients and persisted with medication in 20 patients at follow-up. The procedure was well tolerated by all.     

Temporary epicardial pacing after cardiac surgery: a practical review. Part 2: Selection of epicardial pacing modes and troubleshooting

The first part of this two-part review discussed the indications for various types of epicardial pacing systems and an overview of the routine care of a pacemaker-dependent patient. Dual chamber temporary pulse generators now feature many of the refinements developed initially for use in permanent pacemakers. Few of these are utilised in the immediate postoperative period, often solely due to lack of familiarity with all but basic functions. The second part of the review deals with the selection of pacing modes. Troubleshooting real and apparent pacemaker malfunctions, including manual adjustment of parameters such as the AV interval, post atrial refractory period and upper rate limit, to avoid over- and undersensing, cross-talk and pacemaker-mediated tachycardia will also be addressed.     

Determination of thresholds of external cardiac pacing during anesthesia

The efficacy of transcutaneous pacing was studied in 33 patients during general anaesthesia. The temporary pacing was effective in all cases. Stimulation thresholds ranged from 85 to 150 mA (mean : 110 +/- 17). In all 33 patients, external pacing was effective in producing a pulse without significantly reducing arterial pressure. Stimulation thresholds were only influenced by electrode position; age, weight, thoracic diameter and cardiothoracic ratio did not have any effect on them. No adverse effects of transcutaneous pacing were recorded. Transcutaneous pacing can be an alternative to transvenous right ventricular endocardiac pacing in the operating room in some circumstances.     

Temporary left ventricular pacing improves haemodynamic performance in patients requiring epicardial pacing post cardiac surgery.

OBJECTIVE: In the 1990s, sequential atrio-ventricular pacing demonstrated haemodynamic benefit relative to right ventricular pacing in patients with sinus rhythm requiring pacing post cardiopulmonary bypass. The benefit of biventricular pacing has been demonstrated in non-surgical patients with severe left ventricular dysfunction. It was hypothesised that left ventricular pacing would increase cardiac output in surgical patients. We report the findings of a prospective trial of left ventricular pacing with active lead placement on the anterior or posterior left ventricular surface, compared to standard practice of active lead placement on the right ventricular surface. METHODS: Twenty five patients with left ventricular dysfunction underwent pacing with active lead placement on the right ventricle (control), the anterior left ventricle and the posterior left ventricle in random order, with each pacing mode of 10 min duration, following cardiopulmonary bypass. Haemodynamic parameters were measured with a thermodilution pulmonary artery catheter. Patients provided their control values. RESULTS: In the 25 patients studied, pacing with the active lead posteriorly on the left ventricle increased cardiac index from 2.74 to 3.08 l/min per m2 (P=0.019). Significant increases in mean arterial pressure with the use of this pacing mode were observed. There were no complications relating to application or removal of the left ventricle pacing leads. CONCLUSIONS: Left ventricular pacing with active lead placed on the postero-lateral left ventricular wall affords haemodynamic benefit to cardiac surgical patients.     

Simplified physiological pacing after cardiac surgery

Temporary pacing wires are routinely placed at the end of cardiac surgery. These pacing wires are helpful in maintaining patients with postoperative bradycardias, and physiological pacing is also more desirable in critically ill patients. We herein report our simplified procedure for atrial pacing. This technique uses commercially available intravenous pacing catheters. The catheter is passed through the skin, and its tip is placed at the pericardial oblique sinus just between the right and left pulmonary veins. Atrial pacing is then initiated with a temporary pulse generator. This procedure is simple and effective for patients undergoing cardiac surgery. We also report two clinical cases that satisfactorily underwent atrial pacing using this procedure.     

Oropharyngeal dysphagia after cardiac operations

Background. As many as 15% of hospitalized patients have oropharyngeal dysphagia. The incidence and causes of postoperative oropharyngeal dysphagia (OD) in patients having cardiac operations are poorly documented and the best treatment is uncertain. We undertook a study to evaluate OD in patients having cardiac operations.

Methods. As part of a quality improvement project, all patients operated on in 1998 and 1999 were monitored for the signs or symptoms of OD. Patients with OD had diagnostic and therapeutic interventions to limit adverse outcomes. At the end of the 2-year evaluation period, patient risk factors, diagnoses, results of interventions, and outcomes were measured.

Results. Thirty-one out of 1,042, patients (3%) had OD. OD is more common in older patients (p < 0.0001) with diabetes (p = 0.02), renal insufficiency (p = 0.012), hyperlipidemia (p = 0.046), and preoperative congestive heart failure (p < 0.0001), and in those having noncoronary artery bypass procedures (p < 0.0001). One patient with OD died from respiratory arrest, presumably secondary to aspiration. Modified barium swallow (MBS) identified oral dysphagia in 2 patients, pharyngeal dysphagia in 7 patients, and both oral and pharyngeal dysphagia in 17 patients. One patient had a structural defect (cervical osteophyte) causing dysphagia and 4 patients had no identifiable cause of dysphagia on MBS. Postoperative neurologic complications are more common in patients with OD. Ten of 31 patients (32%) with OD had some new neurologic complication after operation compared with 36 of 1,011 (3.5%) who had a postoperative neurologic problem without OD. In 19 patients with OD no cause for swallowing difficulty was identified. Specifically, no metabolic, myopathic, or infectious abnormalities were identified in any patient with OD. Hospital charges were significantly increased in patients with OD ($69,320 versus $36,087, p < 0.0001). Therapy consisting of modification of eating behavior and swallowing technique and in some severe cases enteral or parenteral feeding was successful in all patients except 1, but 4 patients required more than 4 months of supportive care before return to oral feeding was possible.

Conclusions. OD is associated with increased cost and morbidity. Older patients with diabetes, preoperative heart failure, and renal insufficiency are at increased risk for OD. Early recognition and intervention is likely to result in satisfactory outcome but may be associated with a protracted postoperative course.     

Temporary A-V sequential pacing using transluminal pacing electrodes

A case is presented which describes the initiation of atrialventricular (A-V) sequential pacing using atrial epicardial wires and an in situ transluminal ventricular pacing probe. A 68year-old female with a permanent A-V sequential pacemaker was scheduled for elective aortocoronary bypass. Following sternotomy, pacing function was converted to ventricular pacing (WI) with the use of electrocautery. A Chandler® V-pacing probe was introduced through a Paceport® (American Edwards) pulmonary artery catheter and with a paced increase in ventricular rate, the cardiac output increased from 2.8 to 3.2 L · min^-1. At the conclusion of cardiopulmonary bypass the patient was in sinus rhythm at a rate of 67 · min^-1 and was paced to a faster rate using bipolar atrial epicardial wires. The patient subsequently developed intermittent heart block so temporary A-V sequential pacing was established using atrial epicardial wires and the in situ ventricular pacing probe. Pacing was achieved at routine generator output settings of seven milliamps (mA) for both atrium and ventricle and at an A-V interval of 0.120 sec. This resulted in an immediate increase in cardiac output from 3.3 to 4.1L- min^-1. The compatability of these two pacing systems offers an increased margin of safety in cardiac surgery patients requiring atrial pacing, who are at risk for developing postoperative heart block.     

Prediction of risk in noncardiac operations after cardiac operations

To determine the preoperative variables affecting the mortality rate and the development of severe complications in patients who have had myocardial revascularization or a valve replacement and who then undergo a noncardiac operation, we retrospectively studied data from 120 such patients over the 5 years from 1982 through 1986. Thirty-six percent of patients had a noncardiac operation during the first month after the cardiac operation. The mortality rate was 11%, and the morbidity rate was 56%. The statistical comparison of the predictive accuracy of postoperative complications of three simple, widely used classifications (American Society of Anesthesiologists physical status, New York Heart Association classification, Massachusetts General Hospital cardiac risk index) demonstrated the superiority of the simplified three-class cardiac risk index (Massachusetts General Hospital-cardiac risk index; predictive accuracy of 84%). In a multivariate discriminant analysis of 21 variables in this population, five variables (myocardial infarction in previous 6 months, S3 gallop or jugular vein distention, arrhythmia on last preoperative electrocardiogram, emergency operation, delay between cardiac and noncardiac operation) were identified as being the most predictive of a postoperative complication. When these variables were used in the function (DF3) obtained by linear discriminant analysis, the prediction accuracy of a postoperative complication reached 83%. Performance of the new models in a prospective validation population remained satisfactory (75% for Massachusetts General Hospital-cardiac risk index three-class index and 72% for DF3). Extensive statistical analysis of our data tested by a validation study provided simple predictive models based on clinical variables easily available even in emergency situations.     

Permanent cardiac pacing after the Fontan procedure

Permanent cardiac pacing after a Fontan procedure is complicated by complex cardiovascular anatomy. Of 332 patients undergoing the Fontan procedure at the Mayo Clinic, we evaluated 15 who postoperatively required permanent pacing (mean age 16.5 years, range 4 to 31 years). Underlying congenital cardiac defects included univentricular heart in nine patients, double-outlet right ventricle in three, and tricuspid atresia in three. The indication for pacing was postoperative heart block in seven patients, congenital heart block in five, postoperative sick sinus syndrome in two, and heart block because of previous operation in one. Pacemakers were implanted immediately postoperatively in 11 patients and 12 to 57 months later in four patients. VVI systems were used in nine patients, DDD in four, AAI in one, and a Medtronic Activitrax VVI in one. All ventricular leads were epicardial. Four atrial leads were transvenous endocardial and one was epicardial. Three patients died 4, 9, and 69 months later of causes unrelated to pacing. Among the 12 survivors, mean follow-up was 34 months (range 1 to 107 months). Two patients had a total of three episodes of loss of ventricular capture because of increased chronic thresholds. Our current approach to pacing after a Fontan procedure includes (1) intraoperative placement of temporary atrial and ventricular electrodes, (2) intraoperative attachment of a permanent ventricular epicardial lead for congenital or surgically induced high-grade atrioventricular block, (3) postoperative insertion of transvenous atrial leads if dual-chamber pacing is indicated, and (4) use of programmable pulse generators with high output capability.     

Influence of external cardiac pacing on cerebral oxygenation measured by near‐infrared spectroscopy in children after cardiac surgery

Background: The brain of children in the early period after repair of congenital heart defects with cardiopulmonary bypass (CPB) may be more vulnerable to hemodynamic changes because of impaired cerebral autoregulation. During postoperative testing of the external temporary safety pacer, we performed desynchronizing ventricular pacing (VVI) while monitoring cerebral oxygenation using near‐infrared spectroscopy (NIRS). Methods: We prospectively investigated 11 children (6 girls, 5 boys). Mean age was 6.1 months (±3.8 months) and mean weight: 5.3 kg (±1.5 kg). We performed measurements at four study steps: baseline I, VVI pacing, baseline II and atrial pacing (AOO) to exclude effects of higher heart rate. We continuously measured the effects on hemodynamic and respiratory parameters as well as on cerebral tissue oxygenation index (TOI). Hemoglobin difference (HbD) was calculated as a parameter for cerebral blood flow (CBF). Results: Ventricular pacing leads to a significant decrease in arterial blood pressure and central venous saturation accompanied by an immediate and significant decrease in TOI (63.3% ± 7.6% to 61.5% ± 8.4% [P < 0.05]) and HbD (0.51 ± 1.8 μmol·l⁻¹ to −2.9 ± 4.7 μmol·l⁻¹ [P < 0.05]). Conclusion: Cardiac desynchronization after CPB seems to reduce CBF and cerebral oxygenation in children.     

Chylopericardium after cardiac operations in children

BACKGROUND: Chylopericardium is a rare complication after operation for congenital heart disease. The incidence and clinical outcomes in a large cohort of surgical patients are unknown. METHODS: We retrospectively reviewed the clinical records spanning more than 12 years in a single institution of 16 children with chylopericardium after cardiac operation. RESULTS: We identified 16 patients with chylopericardium between 1985 and 1997. Chylopericardium was isolated in 7 patients. Twelve patients required pericardial drainage. Patients with isolated chylopericardium presented late and were treated initially as having postpericardiotomy syndrome. Three patients underwent thoracic duct ligation. There were two late deaths unrelated to the chylothorax. Associated diagnoses were internal jugular vein thrombosis and recurrent pulmonary vein obstruction (1 of 16 patients), an associated syndrome but not Turner or Noonan (10 of 16), superior cavopulmonary or total cavopulmonary anastomosis (7 of 16), atrioventricular septal defect repair (5 of 16), and repair of tetralogy of Fallot (2 of 16). CONCLUSIONS: Percutaneous drainage to relieve tamponade together with a low-fat or medium-chain triglyceride diet results in resolution in most cases of postoperative chylopericardium. If a pericardial effusion enlarges, fails to clear on aspirin therapy, or presents late after hospital discharge, diagnostic pericardial tap and a low-fat diet are indicated.