Effects of defibrillator implantation testing on myocardial metabolism.

BACKGROUND: The effects of fibrillation/defibrillation episodes (FDEs) during defibrillator implantation on myocardial metabolism were investigated at various defibrillation energies in patients with different cardiac pathologies. METHODS: Myocardial lactate extraction (MLE) was examined during defibrillation threshold (DFT) testing in patients with either coronary artery disease (CAD, n = 20) or non-ischemic cardiomyopathy (CM, n = 10). Defibrillation pulses were released 15 seconds after induced fibrillation. A test cycle of four FDEs separated by 2-minute intervals was applied in each case. RESULTS: Mean MLE decreased significantly from 28 +/- 4% before FDEs to 8 +/- 5% immediately after all episodes in CAD patients, but recovered to 27 +/- 7% within 2 minutes even in patients with reduced left-ventricular function. In patients with CM mean MLE decreased markedly from 29 +/- 3% to -11 +/- 3% immediately after each FDE but increased to baseline (33 +/- 8%) within the recovery period. MLE changes were independent of defibrillation energy in all cases. CONCLUSIONS: Myocardial lactate production, suggesting cardiac ischemia, was observed in patients with CM, but not in patients with CAD. But recovery of myocardial lactate extraction was not faster in CAD patients, indicating that the fixed FDE cycle used was well tolerated by all patients.

Mediastinitis after cardiac surgery--epidemiology and current treatment.

Mediastinal infection is a feared complication observed after 0.4%-5% of cardiac operations. Even today the mortality remains as high as 20%-40%. We discuss the aetiology, mechanisms, prevention, diagnosis, and medical management. The staging system for mediastinal wound infections developed at a joint conference of German cardiac surgical centres is presented. The use of parenteral polyvalent immunoglobulins is also discussed.

Atrial fibrillatory electrogram measurement allows atrial lead placement in patients who develop atrial fibrillation during permanent dual chamber pacemaker implantation.

The benefit of DDD(R) pacing is proven even in patients with intermittent atrial fibrillation. Atrial fibrillation developing during dual chamber pacemaker implantation creates a difficult problem. Maneuvers to reestablish a stable atrial rhythm often are required if atrial fibrillation sets in. This study was performed to determine if atrial lead placement can be performed with acceptable long-term results in the presence of atrial fibrillation. Twenty-one patients in whom atrial fibrillation developed during permanent pacemaker implantation were included in this study. In 12 patients, episodes of intermittent atrial fibrillation had been documented before the procedure. Screw-in leads were used in 15 patients and J-shaped passive fixation leads in 6 patients. All leads were bipolar. The intraoperative atrial fibrillation electrogram amplitudes ranged from 0.9 to 3.2 mV (mean 1.8 +/- 0.6 mV). One patient required lead revision due to a high atrial pacing threshold after conversion to SR. One patient remained in atrial fibrillation at 3-month follow-up. The other 20 patients converted to SR, 11 of whom had intermittent atrial fibrillation with successful mode switch activation. P wave amplitudes were 2.8 +/- .6 mV (range 1.4 to 4.0 mV) after conversion to SR. The mean atrial pacing threshold was 1.1 +/- 0.5 V (range 0.5 to 3.5 V). Placement of atrial leads in patients who develop atrial fibrillation during pacemaker implantation is feasible; fibrillatory electrogram amplitudes showed a good correlation with the atrial signal after conversion to an organized atrial rhythm (r = 0.698). Acceptable atrial pacing thresholds can be expected as well.

Myocardial lactate extraction during repeated fibrillation/defibrillation episodes in defibrillator implantation testing.

Intraoperative testing with several fibrillation/defibrillation episodes (FDEs) is routinely performed during defibrillator implantation. Testing is considered safe even in patients with severe cardiac impairment, provided the recovery timespans and number of FDEs are adapted to the individual patient. Myocardial lactate extraction (MLE) was examined in two testing protocols. In 30 patients with coronary artery disease defibrillator implantations were performed under intravenous anesthesia. A percutaneous catheter was positioned into the coronary sinus (CS) underfluoroscopy. Two groups were randomly formed: group A (n = 20, mean number of FDEs: 4.2/patient) with 2 minutes waiting time between FDEs, and group B (n = 10, mean number of FDEs 4.1/patients) with 10 minutes between FDEs. Defibrillation pulses were released 15 seconds after T wave shock induced fibrillation. To estimate MLE, arterial and CS blood samples were collected before and after each FDE. After the last FDE, samples were obtained after 5, 10, and up to 20 minutes. In group A, MLE fell from a baseline value of 29.6% +/- 3.6% before the FDEs to 7.8% +/- 5.4% immediately after the episodes. MLE recovered to 27.2% +/- 6.5% within 1 minute and overshot to 35.6% +/- 5.8% within 5 minutes. In group B, MLE decreased from 37.6% +/- 7.5% to 15.1% +/- 8.1% immediately after each FDE and rose to its original value (33.6 +/- 7.8) within the 5-minute recovery period. MLE decreased immediately after each FDE, and recovered within 1 minute even in poor left ventricular function. For full MLE recovery a 2-minute wait between episodes is sufficient, if the total number of FDEs does not exceed four.

Coronary artery bypass grafting in a patient with type II heparin associated thrombopenia.

Two types of heparin-associated thrombopenia can be distinguished. Patients with the type II condition present a particularly difficult management problem when they require full anticoagulation. There is no consensus about the proper anticoagulation management for type II patients who have to undergo cardiopulmonary bypass. The case is reported of a type II heparin-associated thrombopenia patient who underwent successful aortocoronary saphenous vein grafting. Sodium-danaparoid was used for anticoagulation. The anti-factor Xa level was kept below the value reported in the literature for patients undergoing cardiopulmonary bypass. No fibrin formation was observed during the time of cardiopulmonary bypass, nor was any severe postoperative haemorrhage seen, as is frequently described in the literature.

Intravascular ultrasound (IVUS) examination reverses therapeutic decision from percutaneous intervention to a surgical approach in patients with alterations of the left main stem.

Intravascular ultrasound (IVUS) represents a new method to assess vessel lumen and wall morphology. To prospectively evaluate the usefulness of IVUS for further therapeutic decisions in left main stem (LM) lesions with unclear angiographic definition, this study was launched. We studied 56 patients with significant stenosis of the LAD and/or LCX arteries and questionable LM morphology. 30-MHz IVUS catheters with 2.9 or 3.2 F outer diameters were used. A significant luminal reduction of the left main stem was defined as an area stenosis greater than 50% or a minimal luminal diameter smaller than 3 mm as determined by IVUS. 36 of 56 patients (61%) fulfilled these criteria. Additionally, 12 patients showed a ruptured plaque within the LM. 30 of these 36 patients were originally thought to be candidates for angioplasty. After positive IVUS 34 of these 36 patients were sent to surgery. No perioperative ischemic complications occurred. In angiographically unclear left main stem findings. IVUS establishes a definitive diagnosis. After IVUS confirmation of significant left main stem pathology operative management should be the preferred approach as compared to transluminal coronary interventions. However, prospective randomized studies are needed to define the most efficient approach.

Single-lung transplantation in a patient with cystic fibrosis and an asymmetric thorax.

We report metachronous single-lung transplantation for cystic fibrosis after contralateral pneumonectomy. Kyphoscoliosis and mediastinal shift required careful donor-lung sizing with computed tomography and was not dependent on typical parameters. Severe reperfusion injury was treated with nitric oxide, C1-esterase inhibitor, and continuous venovenous hemodialysis. The patient was extubated on the fifth postoperative day and is alive and well. We conclude that single-lung transplantation after contralateral pneumonectomy for patients with cystic fibrosis and an asymmetric chest and evident lung volume mismatch may be an acceptable functional therapeutic option.

Results of cardiac operations in five kidney transplant patients.

Because of the paucity of literature reports about cardiac operations in renal-transplant patients we performed a retrospective study encompassing all such patients operated upon in our institution in 1993 and 1994. During this time 5 renal transplant patients underwent cardiac surgical procedures between 1 and 9 years after transplantation: in 4 patients coronary artery bypass grafting (CABG) was carried out and in one patient aortic valve replacement. We analyzed pre-, peri-, and postoperative data. Late results were obtained by questionnaire from the patients' primary physicians. Short- and long-term results were excellent. Mortality was 0%. At late follow-up (8-23 months) all patients were in NYHA class II or better. Postoperatively all patients experienced a clear improvement of their cardiac symptoms. None of the transplanted kidneys deteriorated. One patient who had to undergo intermittent hemodialysis preoperatively improved so much that she did not require any dialysis postoperatively. Although the total number of patients in this study is limited we believe it can be stated that renal transplant patients can undergo cardiac operations with generally good results.

Bilateral inferior vena cava with azygos continuation but without congenital heart disease complicates routine venous cannulation for cardiopulmonary bypass in an adult.

Attempted venous cannulation with a dual-stage cannula for cardiopulmonary bypass in routine coronary revascularization led to the discovery of an abnormal inferior vena cava in a 65-year-old patient. The operative and postoperative course of the patient were not affected by the inferior caval anomaly. The detailed infradiaphragmatic venous anatomy was elucidated later by MRI and showed bilateral inferior caval veins with azygos continuation. Although this malformation of the inferior cava is rare in adults, the occurrence should be known. Quick recognition and handling should be achieved if detected during cannulation for cardiopulmonary bypass.

One-year experience with the Edwards stentless "Prima" aortic bioprosthesis.

The aortic stentless bioprothesis are expected to have an improved hemodynamic function because of their lack of a sewing ring and stents. From April 1993 to March 1994 we implanted aortic Edwards "Prima" stentless bioprotheses in 21 patients suffering from aortic valve disease. In some patients additional cardiac procedures (CABG, MVR, tricuspid valve anuloplasty) were performed. The patients' age ranged from 56 to 78 years. The size of the bioprothesis ranged from 23 mm to 29 mm in diameter. We used either the subcoronary or the "mini-root" continuous suture technique. Aortic cross-clamp time ranged from 52 min to 128 min. There was no operative mortality. The intraoperative measurements showed that the pressure gradient across the aortic valve was very low or even undetectable. The echocardiographic control after 1 year revealed very good valve function. Our initial experience with this new valve shows a very good short-term result with an only slightly longer cross-clamp time. Since the valve has not been available for a long line, long-term results could not yet be observed.

Autologous bone transplant after sternal resection.

Two patients underwent subtotal sternal resection for tumors of the sternum. Anatomical and functional reconstruction was performed with bone fragments harvested from the internal lamina of both iliac wings. There were no infections and no instabilities. Late postoperative follow-up included CT-scan of the thorax and pulmonary function testing, which was not compromised. We conclude that this surgical approach is very efficient in regard to function and chest wall stability.

Exposing the circumflex coronary artery: the heartflip technique.

A method to expose the circumflex coronary artery in its course in the atrioventricular groove is introduced. No special equipment or assistance is required. This method also can be applied to expose the obtuse marginal branches of the circumflex coronary artery. Adverse effects have not been observed.

Postoperative disruption of an internal prong-type caval filter--a case report.

A prong-type caval filter fractured and disintegrated within 4 months after its implantation in a 21-year-old woman. The fragments and the disrupted filter were removed surgically and the vena cava was plicated. Seven similar cases were found in the literature. Possible etiologic factors and measures to avoid this complication are discussed.

One-stage intrathoracic repair of extended aortic aneurysms.

Aneurysms of the entire thoracic aorta are usually approached in two to three stages. From 1990 to 1994, we performed one-stage aortic replacement from the root to the diaphragm in 16 patients (8 men and 8 women with a mean age of 55.7 years, range 49 to 73). There were 11 type A dissections, 7 of which were acute. Six patients underwent aortic valve reconstruction; seven had aortic root replacement by Bentall or Cabrol techniques. In two cases, the innominate artery had to be replaced by a vascular graft separately in addition to reimplantation of the supraaortic branches as an island flap into the arch prosthesis. In eight cases, a median sternotomy was used; eight had a bilateral transverse thoracotomy. The procedure was performed under deep hypothermic circulatory arrest in all cases (mean duration 50.5 min, range 38 to 62 min). Two patients, both operated upon for an acute dissection, expired perioperatively: one due to a bronchopneumonia, and one because of a thrombosed Cabrol graft to the right coronary artery. No patient developed bleeding or neurological complications. At a mean follow-up of 26.9 months (1 to 50 months), all patients discharged from the hospital were still alive. Four patients underwent subsequent thoracoabdominal aortic replacement. This experience suggests that complete thoracic aortic replacement can be performed in a single session with an operative risk comparable to that of the conventional two-stage approach. The bilateral transverse thoracotomy affords excellent exposure. The lack of spinal cord ischemia may be the result of spinal cord protection with hypothermic circulatory arrest and use of the open-clamp technique.