Cardiac surgery and heparin induced thrombocytopaenia (HIT): a case report and short review.

This patient presented for emergency cardiac surgery following two episodes of thrombocytopaenia, one before and one associated with exposure to unfractionated heparin in a seven-week period of intensive care management. Although the diagnosis of heparin induced thrombocytopaenia (HIT) was uncertain on clinical grounds when assessed by current criteria, the positive antibody status directed management in accordance with the internationally recognised guidelines published by the American College of Chest Physicians (ACCP) Evidence-based Clinical Practice Guidelines. An alternative anticoagulant to unfractionated heparin was indicated for cardiopulmonary bypass. Bivalirudin was selected because of recent literature supporting its safe use.

MRI of partial anomalous pulmonary venous return (scimitar syndrome).

We report a case of anomalous pulmonary venous drainage into the inferior vena cava (scimitar syndrome). Cine MRI and 3-D contrast-enhanced MR angiography provides an non-invasive diagnostic technique in the evaluation of anomalous pulmonary venous return.

Reoperation and coarctation of the aorta: the need for lifelong surveillance.

BACKGROUND: We report a series of reoperations in 23 patients who had undergone previous aortic coarctation repair. METHODS: The medical records of these patients were reviewed, and the patients were followed up by telephone interview. Mean age at reoperation was 25 years. There was a mean of 18 years between initial coarctation repair and reoperation. Indications for reoperation included recoarctation (9 patients), aortic aneurysm (8), aortobronchial fistulas with exsanguinating hemorrhage (2), subaortic stenosis (1), ruptured thoracic aneurysm (1), ruptured sinus of Valsalva aneurysm (1), and supramitral stenosing ring (1). RESULTS: There were no specific intraoperative complications. Three patients required reexploration for bleeding. An acutely ischemic lower limb developed in 1 patient secondary to a common femoral artery embolus, which necessitated embolectomy. CONCLUSIONS: Reoperation for postcoarctation repair patients can be performed with good results. Sudden life-threatening hemorrhage due to aortobronchial fistulas in patients having undergone Dacron patch aortoplasty, as well as long-term obstructive phenomena seen anywhere along the left ventricular outflow tract, make lifelong surveillance of these patients mandatory.

Use of the Medtronic Freestyle valve as a right ventricular to pulmonary artery conduit.

BACKGROUND: We have used the Medtronic Freestyle bioprosthesis as a right ventricular to pulmonary artery conduit recently in an attempt to overcome some of the problems associated with homografts and stented xenografts. The aim of this study was to review the performance of this prosthesis. METHODS: Prospectively collected data for patients having Freestyle bioprostheses implanted as a right ventricular to pulmonary artery conduit were reviewed to assess clinical outcome and echocardiographic results. RESULTS: Thirteen patients aged 13 days to 22.5 years (median, 7.9 years) underwent either primary repair (n = 5) or change of conduit (n = 8) using the Freestyle bioprosthesis. One neonate with truncus arteriosus died postoperatively of pulmonary hypertension. One conduit was explanted 27 months after repair of neonatal truncus arteriosus. There has been no incidence of significant prosthetic regurgitation, thromboembolism, or endocarditis at mean follow-up of 10.1 months (range, 2 weeks to 29 months). CONCLUSIONS: The Medtronic Freestyle valve is a reliable pulmonary valve substitute in the short term. Early results justify continued clinical use of the device in this setting with close follow-up.

Transcaval repair of the sinus venosus syndrome.

BACKGROUND: Surgical correction of the sinus venosus syndrome has been associated with sinus node dysfunction and venous obstruction postoperatively. We present the long-term follow-up of a lateral transcaval approach, which closes the atrial communication and corrects the partial anomalous pulmonary venous connection to the superior vena cava with the use of a simple pericardial patch. METHODS: The records of 66 patients undergoing repair between April 1981 and April 1997 were examined. Mean age at repair was 10.2 years (range, 1.5-65 years; median, 5 years). Six patients had a left superior vena cava, 4 had an additional atrial septal defect, and 2 had coronary artery bypass grafts. Immediate and long-term follow-up included physical examination, electrocardiography, transthoracic echocardiography, and use of a 24-hour ambulatory Holter monitor. Sinus node function, incidence of significant arrhythmia, and evidence of mechanical venous obstruction were assessed. RESULTS: Follow-up data were available for 64 (97%) patients for a mean follow-up of 4.1 years (range, 1-9 years). There were no deaths. No evidence of residual atrial septal defect, superior vena cava, or venous obstruction were found by echocardiography. On electrocardiography all patients were in sinus rhythm, with no arrhythmia seen. Holter monitoring was performed at a mean of 7.3 years postoperatively. All patients had normal sinus node function, and no sustained atrial arrhythmia was seen. CONCLUSION: Transcaval repair is a simple technique that does not interfere with sinus node function. There is no evidence to suggest that this approach leads to venous obstruction.

Mechanism, localization and cure of atrial arrhythmias occurring after a new intraoperative endocardial radiofrequency ablation procedure for atrial fibrillation.

OBJECTIVES: The purpose of this study was to test a new pattern of radiofrequency ablation for atrial fibrillation (AFib) intended to optimize atrial activation, and to demonstrate the usefulness of catheter techniques for mapping and ablation of postoperative atrial arrhythmias. BACKGROUND: Linear radiofrequency lesions have been used to cure AFib, but the optimal pattern of lesions is unknown and postoperative tachyarrhythmias are common. METHODS: A radial pattern of linear radiofrequency lesions (Star) was made using an endocardial open surgical approach in 25 patients. Postoperative arrhythmias were induced and characterized during electrophysiological studies in 15 patients. RESULTS: The AFib was abolished in most patients (91%), but atrial flutter (AFlut) occurred in 96% of patients postoperatively. At postoperative electrophysiological studies, 37 flutter morphologies were studied in 15 patients (46% spontaneous, cycle length [CL] 223 +/- 25 ms). Seven mechanisms (lesions discontinuity, n = 6; focal mechanism, n = 1) of AFlut were characterized in six patients. In these cases, flutter was abolished using further catheter radiofrequency ablation. In the remaining cases, flutter was usually localized to an area involving the interatrial septum, but no critical isthmus was identified for ablation. After 16 +/-10 months, 15 patients (65%) were asymptomatic with (n = 3) or without (n = 12) antiarrhythmic medications. Eight (35%) patients had persistent arrhythmias. Postoperative atrial electrical activation was near physiological. CONCLUSIONS: The AFib maybe abolished using a radial pattern of linear endocardial radiofrequency lesions, but postoperative AFlut is common even when lesions are made under optimal conditions. Endocardial mapping techniques can be used to characterize the flutter mechanisms, thus enabling subsequent successful catheter ablation.

Commissuroplasty: a method of valve repair for mitral and tricuspid endocarditis.

BACKGROUND: We describe our experience with a technique of cusp commissuroplasty to reconstruct atrioventricular valves damaged by endocarditis of the commissure and adjacent cusps. METHODS: We operated on 3 patients with mitral endocarditis and one patient with previous tricuspid endocarditis. Infected leaflet tissue was excised from each side of the commissure, leaving a defect between one quarter and one third of the valve area. Using the technique of valve commissuroplasty, leaflet remnants were reapposed at the cut edges to obliterate the commissure. The residual D-shaped defect between the apposed leaflets and annulus was either closed directly or patched with pericardium, depending on the size of the defect. RESULTS: Constructing unicommissural mitral and bicuspid tricuspid valves restored leaflet continuity. One patient was lost to follow-up. Postoperative echocardiography performed at a mean interval of 14.7 months showed competent and nonobstructed valves. There was no recurrent endocarditis at a mean follow-up time of 15.7 months. CONCLUSIONS: The technique of cusp commissuroplasty can be used to reconstruct atrioventricular valves that have been damaged by endocarditis of the commissure and adjacent cusps.

Right ventricular dysfunction in congenitally corrected transposition of the great arteries.

Although right ventricular (RV) dysfunction is an important complication in subjects with congenitally corrected transposition of the great arteries, its pathogenesis is poorly understood. We assessed the role of RV myocardial perfusion and found perfusion defects at rest in all 20 patients, involving 4.6 +/- 2.3 of a total of 12 segments; the extent of the resting perfusion defects correlated inversely with the RV ejection fraction.

Tunnelling versus open harvest technique in obtaining venous conduits for coronary bypass surgery.

BACKGROUND: The tunnelling as opposed to the open harvest technique for harvesting long saphenous vein for coronary artery bypass procedures is a less frequently used technique as it requires more handling of the vein and this may induce trauma. This study aims to compare the degree of endothelial denudation and donor site morbidity between the two different harvest techniques. METHODS: Saphenous vein segments in 78 patients (45 in tunnelling versus 33 in open harvest group) undergoing coronary artery bypass procedures were examined by light microscopy and graded according to the extent of endothelial denudation varying from grade 1 (most preserved) to grade 6 (>90% endothelial denudation). Clinical parameters relating to donor site morbidity including leg wound pain and infection were also assessed. RESULTS: There was no statistical difference in the age, sex, macroscopic vein quality, length and time taken to harvest the veins between the two groups. The tunnelling technique always used thigh saphenous vein whereas nearly a third of veins harvested by the open harvest technique were lower leg veins (P=0.001). The tunnelling technique resulted in an endothelial score of 2.5 compared with 3.3 for the open harvest technique (P < 0.001). In addition, saphenous vein tunnelling resulted in significantly less leg wound pain (1.2 vs. 1.8, P=0.001), no leg wound infection (compared with 12.2% in open harvest group, P=0.02) and produced cosmetically more acceptable scars. Furthermore, length of hospital stay was significantly prolonged to 19.3 days in those with leg wound infection compared to 8.7 days in those without leg wound infection (P < 0.001). CONCLUSIONS: These results show that saphenous vein tunnelling is an attractive alternative to the open harvest technique in obtaining venous conduits for coronary artery bypass procedures.

Ventricular assist devices in pediatric cardiac surgery.

BACKGROUND: Early experience in other centers with pediatric assist devices has been favorable. METHODS: Prospectively we examined our first 13 patients between January 1992 and September 1994. RESULTS: Thirteen children underwent ventricular assistance at Royal Alexandra Hospital for Children. Age ranged from 4 days to 30 months, weight from 2.9 kg to 17 kg. Ventricular assistance was employed from 1.5 hours to 190 hours. Of 12 surgical patients, 8 required left ventricular assistance to be weaned from cardiopulmonary bypass after correction of congenital defects, and 4 required support in the postoperative period for refractory low cardiac output. A child was supported after a kick to the chest by a horse caused cardiogenic shock. All 13 patients initially responded to ventricular assistance and 7 remain alive. Of the deaths, 2 were neurologic, 2 due to myocardial failure, and 2 to sepsis. The major complications in the first days were hemorrhage and tamponade. Later problems included thrombosis of the circuit despite systemic heparinization, and a cannula-related tear to the anterior mitral leaflet. The 7 survivors are well after 3 to 32 months. CONCLUSIONS: Despite the mortality and complications, we are encouraged by these results, in the light of almost certain death for all 13 patients without ventricular assistance.

Salvage of infected truncus repair using rifampicin-impregnated gelatin-sealed graft.

An infant suffered sternal infection and ventricular septal patch dehiscence after a truncus arteriosus repair. Successful reoperation used rifampicin-impregnated gelatin-sealed Dacron to repair the recurrent ventricular septal defect and replace the contaminated conduit. This was an effective solution to a potentially lethal surgical complication.

Localized supravalvar aortic stenosis: a new technique for repair.

The deformity in supravalvar aortic stenosis includes generalized thickening of the tissues of the aortic root with a fairly normal sized aortic valve ring. The thickened tissues may obstruct the origins of the left and right coronary arteries. We have repaired 2 cases with complete excision of the stenosing ring below the level of the commissures of the aortic valve into the sinuses, to the level of the left and right coronary arteries.

Effect of ventriculotomy on postinfarction ventricular tachycardia in a canine model.

The antiarrhythmic efficacy of ventriculotomy without further resection or ablation was evaluated in 15 dogs with reliably inducible ventricular tachycardia after experimental myocardial infarction. The dogs were placed on cardiopulmonary bypass and assigned to one of two treatment groups: (1) cardiopulmonary bypass only (control) - 5 dogs, (2) ventriculotomy through the infarct scar - 10 dogs. The effects on induction of ventricular tachycardia were evaluated 2 and 4 weeks postoperatively and infarct histology was examined at the termination of the experiment. All of the control dogs maintained inducible ventricular tachycardia postoperatively. In contrast, ventriculotomy abolished arrhythmia induction in 6 of 10 dogs (p < 0.05). Ventriculotomy resulted in destruction of the surviving subepicardial myocardium overlying the infarct, which is a feature of arrhythmogenic areas in this model of postinfarction ventricular tachycardia. In conclusion, inducibility of ventricular tachycardia in this canine model of myocardial infarction is unaffected by thoracotomy and cardiopulmonary bypass, and is therefore well suited to investigation of surgical antiarrhythmic interventions. Ventriculotomy results in subepicardial scarring and is significantly antiarrhythmic. This effect should be taken into account when evaluating any adjunctive procedure in this model.

Optimal approach to the mitral valve: dissection of the interatrial groove.

Surgical exposure of the mitral valve has challenged surgeons for more than 30 years. Many ingenious, but often complex approaches have been devised during this time. Using the dissection of the interatrial groove to bring the left atrial incision more anterior and medial, we have achieved excellent exposure in more than 300 mitral valve procedures. This simple technique does not lengthen the procedure and is not associated with an increased risk of either early or late morbidity.

Congenital obstruction of the caudal vena cava in a dog.

A 16-week-old female Rottweiler was examined because of labored breathing and abdominal distention. Ascites, hepatomegaly, and pleural effusion were detected during physical and radiographic examinations. Selective angiography revealed a stenotic lesion at the junction of the caudal vena cava and the right atrium. A fibrous diaphragm with a pin-hole orifice was observed at surgery. Clinical signs of disease resolved after successful removal of the membranous obstruction.

Use of desmopressin in the management of aspirin-related and intractable haemorrhage after cardiopulmonary bypass.

Desmopressin (DDAVP) has been used both prophylactically and therapeutically in the management of excessive bleeding after cardiopulmonary bypass. A series of four consecutive cases is presented in which DDAVP was used to treat excessive bleeding, associated with aspirin antiplatelet therapy in three cases and after all other measures had failed in one. The therapeutic use of DDAVP in aspirin-related bleeding after bypass has not been reported previously. There was no measured haemodynamic effect of the regimen used. Bleeding ceased promptly after administration of DDAVP in all cases. No morbidity was observed in any of the patients. The indications for use of DDAVP and postulated mechanisms of action are discussed.

Comparison of early and late dimensions and arrhythmogenicity of cryolesions in the normothermic canine heart.

Little is known about myocardial cryoablation at normothermia and the effect of cryoprobe head size and duration of freeze on final lesion volume. In the present study, cryolesions were created with a carbon dioxide cryoprobe with two head sizes (cylindrical head 6 mm diameter and large circular head 18 mm diameter) in the normothermic canine heart during cardiopulmonary bypass. The duration of freeze (exposure time) varied from 2 to 3 or 4 minutes and the effects on immediate and chronic lesion size were evaluated. Lesions produced by epicardial exposures were compared with intramyocardial lesions created by placing the cylindrical head in a 6 mm stab incision. A minimum of four lesions were created in each dog. Lesion size was evaluated at 0 minutes (iceball) and 24 hours (two dogs), 7 days (one dog), or 4 weeks (five dogs). Iceball diameter was approximately 5 mm larger than chronic lesion diameter regardless of head size or exposure time. Prolongation of exposure time from 2 to 3 minutes resulted in significant increases in the volume of epicardial lesions (cylindrical head: 280 +/- 100 mm3 versus 740 +/- 200 mm3, p = 0.001; circular head: 1200 +/- 100 mm3 versus 2300 +/- 500 mm3, p = 0.007) because of increases in diameter and depth. No further increase in lesion size was observed when exposure time was prolonged from 3 to 4 minutes. A 3-minute intramyocardial exposure with the cylindrical head placed in a stab incision enabled production of transmural lesions (16 +/- 2 mm deep). Two and 4 weeks postoperatively, dogs underwent electrophysiologic study from the right and left ventricular apices. No animals had inducible ventricular tachycardia despite the heterogeneous configuration of the multiple cryolesions. In conclusion, it is possible to produce rapid and predictable ablation of clinically useful volumes of myocardium during normothermic bypass with the use of currently available equipment. Under these conditions, an exposure time of 3 minutes is optimal for a liquid carbon dioxide cryoprobe. Cryolesions should be overlapped by at least 2.5 mm to produce continuous areas of ablation. Multiple cryolesions do not form a chronic substrate for ventricular tachycardia.

Management of ascending aortic dissection: experience with the USCI intraluminal prosthesis and a method of aortic valve repair.

Ten consecutive cases of acute ascending aortic dissection operated on using the USCI intraluminal prosthesis from 1983 to 1986 were reviewed. Diagnosis was achieved by conventional angiography in six cases, by intraarterial digital subtraction angiography in one case, by computerized tomography (CT) scan in two cases and by echocardiography and abdominal ultrasound in one case. An entry site was seen in only five out of six conventional angiograms. At operation six of the 10 had a degree of tamponade. Aortic regurgitation was seen five times, due to dissection in four cases and to Marfan's disease in one. The entry site was controlled in eight cases. Repair using intraluminal prosthesis only was achieved in five cases. Aortic valve repair was added in four out of 10 cases, and in one of these an aorta-to-right coronary graft was also added. One case required aortic valve replacement. A method of aortic valve repair is presented. There were nine survivors, 1-36 months postoperatively. Of these, eight were asymptomatic on no medication. One had severe aortic regurgitation noted 2 months postoperatively and has mildly reduced exercise tolerance. Surgical treatment can be planned if the presence of dissection is proven and involvement of the ascending aorta is demonstrated. Early surgery is important, since six of the 10 cases in this series had tamponade. The intraluminal graft will reliably redirect flow to the true lumen and exclude the dissection from the pericardium. Aortic valve repair can be successful though late replacement may be necessary in some cases. Control of the entry site is not essential to achieve a good clinical result.