Video-assisted thoracoscopic implantation of the left ventricular pacing lead for cardiac resynchronization therapy.

BACKGROUND: To study the feasibility and efficacy of video-assisted thoracoscopic (VAT) placement of the left ventricular pacing lead for cardiac resynchronization therapy (CRT) where the conventional transvenous coronary sinus approach has failed. METHODS: Seventeen patients underwent the VAT procedure. Indications for CRT were ischemic cardiomyopathy in six patients and nonischemic cardiomyopathy in 11. The procedure was performed under general anesthesia with single-lung ventilation. Three 2-cm incisions were used on the left chest wall to place the screw-in lead near the obtuse marginal arteries high on the lateral wall of the left ventricle (LV). RESULTS: The VATS approach was successful in 13/17 (76%) patients. Median procedure time was 75 minutes (range 55-135). A learning curve was observed that appeared to plateau at 75 minutes procedure time after four cases. Median length of hospital stay was 2 days (range 2-8) with one patient requiring intensive care. Satisfactory thresholds and impedances of 2.3 +/- 0.9 V/0.5 ms and 560 ohms, respectively, were achieved at mean follow-up of 226 days. All patients reported symptomatic benefit with reduction in New York Heart Association score from III preoperatively to II postoperatively. CONCLUSIONS: VAT placement of the epicardial pacing lead is feasible, safe, and efficacious. It should be considered in cases where the transvenous route has failed or as an alternative in prolonged or hazardous transvenous procedures.

Non-invasive measurement of peripheral venous oxygen saturation using a new venous oximetry method: evaluation during bypass in heart surgery.

Monitoring of mixed venous oxygen saturation (SvO(2)) is currently performed using invasive fibre-optic catheters. This procedure is not without risk as complications may arise from catheterization. This paper describes an alternative, non-invasive method of monitoring peripheral venous oxygen saturation (SxvO(2)) which, although it cannot replace pulmonary artery catheters, can serve as an adjunct/early warning indicator of when there is an imbalance in oxygen supply and demand. The technique requires the generation of an artificial venous pulse at the finger, thereby causing modulation of the venous blood volume within the digit. The blood volume changes are monitored using an optical sensor. Just as pulse oximetry utilizes the natural arterial pulse to perform a spectrophotometric analysis of the peripheral blood in order to estimate the arterial blood oxygen saturation, the proposed venous oximetry technique uses the artificially generated venous pulse to estimate SxvO(2). A prototype device was tested in a pilot study with patients undergoing heart surgery. Data from this study support the notion that the method is capable of tracking haemodynamic changes and suggests the technique is worthy of further development and evaluation.

Assessment of coronary artery bypass graft flow by intraoperative Doppler ultrasound technique.

A high frequency (10 MHz) Doppler ultrasound pencil probe was used to estimate flow in coronary artery bypass grafts in vitro and during cardiac surgery. In vitro, increasing the angle of the Doppler transducer in relation to flow caused underestimation of the Doppler derived flow, and using the external rather than internal vessel diameter to calculate cross sectional area caused significant overestimation. This overestimation was considerably greater for the internal mammary artery. Accurate flow estimation was obtained in vitro by the Doppler technique, but considerable variation occurred in patients studied during coronary artery bypass surgery. In conclusion, intraoperative Doppler ultrasound provides a qualitative assessment of phasic flow in coronary artery bypass grafts but is less accurate in quantifying absolute flow in these patients.

Bilateral and unilateral use of internal thoracic artery for myocardial revascularization. Comparison of extubation outcome and duration of hospital stay.

The left internal thoracic artery is usually used as arterial conduit for myocardial revascularization; however, there is an increasing popularity of bilateral use of this artery for grafting. We examined 180 patients with both types of arterial conduits to answer whether bilateral use of the internal thoracic artery makes the difference in postoperative extubation outcome and duration of hospital stay in comparison to the unilateral use of this conduit. Ninety-three patients with bilateral conduit and 87 patients with unilateral conduit, with comparable age, cardiopulmonary bypass, and aortic cross-clamp time have been studied. On the basis of statistical and retrospective analysis, we conclude that bilateral use of internal thoracic artery for myocardial revascularization prolongs required postoperative respiratory support (12.0 h against 7.6 h) not affecting the duration of the mean hospital stay.

Randomized comparison of ultrasonic aspiration versus conventional electrocautery for dissection of the human internal thoracic artery.

The most common technique currently employed to harvest the internal thoracic artery for coronary artery bypass grafting is conventional electrocautery. This study compared an alternative method, electrocautery with an ultrasonic aspirator, for harvesting the internal thoracic artery. Patients were randomly assigned to one of six experimental groups (conventional electrocautery, ultrasonic aspirator at settings of 60%, 80%, and 100% power output, and ultrasonic aspirator in 100% CAVI-Pulse modes 1 and 3). Ring segments of internal thoracic artery were studied in an organ bath. Contraction responses were elicited with 123 mmol/L potassium physiologic salt solution, KPSS, KPSS solution containing noradrenaline, and a cumulative noradrenaline dose-contraction curve. Relaxation studies were performed with the vasodilators acetylcholine, bradykinin, and sodium nitroprusside. Forty percent of the electrocauterized vessels were traumatized or damaged and failed to respond to contractile stimuli, whereas only 10% of the vessels in ultrasonic aspirator groups 60%, 80%, and 100% failed to respond. All vessels in the group harvested by ultrasonic aspirator in 100% CAVI-Pulse mode 1 responded, whereas 20% of the vessels in the group harvested by ultrasonic aspirator in 100% CAVI-Pulse mode 3 failed to respond. All settings of electrocautery with an ultrasonic aspirator produced a greater contractile response to KPSS and noradrenaline. Acetylcholine and sodium nitroprusside produced similar relaxations in all groups, but the bradykinin responses were significantly improved in all groups undergoing 100% electrocautery with an ultrasonic aspirator. These results suggest that 100% electrocautery with an ultrasonic aspirator, particularly in 100% CAVI-Pulse mode 1, resulted in less damage and trauma than conventional electrocautery during harvesting of the internal thoracic artery.

Contraction and relaxation of human internal mammary artery after intraluminal administration of papaverine.

The internal mammary artery has become the conduit of choice for coronary artery bypass grafting. Intraluminal papaverine treatment during operation reduces vasospasm and facilitates anastomosis. However, it has been suggested that papaverine may cause intimal damage, and accordingly we have investigated endothelial damage by comparing the responsiveness of internal mammary arteries before and after intraluminal exposure to papaverine (15 mg/mL). Control and papaverine-treated segments of internal mammary artery were obtained from 13 patients undergoing coronary artery bypass grafting and mounted as ring preparations in an organ bath. Cumulative dose contractions to noradrenaline were performed, and the dose producing a half maximal response was determined. Relaxation studies of submaximally contracted arteries were performed using the endothelium-dependent vasodilators acetylcholine and bradykinin and the endothelium-independent vasodilator sodium nitroprusside. In the human internal mammary artery the use of intraluminal papaverine increased the lumen size by 20% (p less than 0.05), and the contractions elicited by noradrenaline were significantly less in the papaverine group than in the control group (p less than 0.05). Endothelium-dependent relaxation to acetylcholine or bradykinin was not affected by papaverine treatment. Endothelium-independent relaxation was the same in both groups, with almost 100% relaxation achieved by sodium nitroprusside. These results indicate that intraluminal papaverine treatment during coronary artery bypass grafting causes a reduction of smooth muscle contraction and does not impair endothelium-dependent relaxation.

Comparative study of the hydrodynamic function of the CarboMedics valve.

The hydrodynamic function of each size of the CarboMedics valve was assessed in a pulsatile flow simulator. The mean pressure difference with respect to forward flow, regurgitant volumes, and total energy loss across each valve were analyzed. The results for the 23-mm aortic and 29-mm mitral CarboMedics valves were compared with those for the St. Jude Medical and Björk-Shiley Monostrut valves. Results showed good hydrodynamic function for each CarboMedics valve, although the pressure difference and total energy loss across the 19-mm aortic valve was high. The hydrodynamic function of the CarboMedics valve was comparable with that of the St. Jude Medical valve. Both valves showed similar leakage volumes, which were significantly larger than that for the Björk-Shiley Monostrut valve. On account of this the total energy loss in the Björk-Shiley valve was significantly less than that for the bileaflet valves in the aortic position. Concern remains for the continuing presence of high closed-valve regurgitation in the bileaflet valves.

Use of expandable wire stents for malignant airway obstruction.

The symptoms of progressive dyspnea and stridor in the setting of malignant airway obstruction are severe and distressing. Conservative nebulizer and oxygen therapy offer little relief, and conventional stenting with T tubes requires a tracheostomy. In this article, we describe our experience with stenting in the treatment of malignant mediastinal disease using the Gianturco expanding metal-wire stents. The technique of placement is simple and the procedure was successful in all 21 cases. Relief of stridor was immediate and the dyspnea usually abated. These benefits continued through the mean survival period after stenting of 134 days (range, 2 to 799 days). The patients required only brief hospitalization (2.83 days) before returning home or to the referring institution. It appears that expandable wire stents may offer a simple yet effective intervention in the palliative treatment of mediastinal malignancy.

Reliability of Allen's test in selection of patients for radial artery harvest.

BACKGROUND: Allen's test is widely used to assess the ulnar collateral blood supply of the hand before radial artery harvest for coronary bypass surgery. This study was performed to determine the optimum cut-off point for a positive Allen's test and the clinical reliability of Allen's test in this role. METHODS: Patients undergoing coronary artery bypass surgery were examined by independent observers using both Allen's test and a Doppler ultrasound test of the ulnar collateral circulation. RESULTS: We examined 93 hands in 47 patients; mean age was 63.6 years. Receiver operating characteristic analysis found that at a conventional cut-off of 6 seconds on Allen's test had a sensitivity of 54.5%, specificity of 91.7%, and diagnostic accuracy of 78.5%. At a cut-off of 5 seconds diagnostic accuracy was maximal (79.6%), with sensitivity of 75.8% and specificity of 81.7%; 100% sensitivity occurred at a cut-off of 3 seconds, with specificity of 27% and diagnostic accuracy of 52%. CONCLUSIONS: At no cut-off point does Allen's test perform satisfactorily as a discriminatory test. It should be replaced by more objective tests, such as Doppler ultrasound.

Midterm evaluation of the Tissuemed (Aspire) porcine bioprosthesis: 493 patients, 506 bioprostheses.

BACKGROUND: Valve durability has been a major concern with bioprostheses, and the Tissuemed (Aspire) porcine bioprosthesis was designed to provide a solution to structural valve failure. Because bioprostheses tend to fail by 8 years, the aim of our study was to determine its midterm durability and performance. METHODS: We reviewed 506 prostheses that were implanted in 493 patients (287 men; mean age 73 +/- 6 years) between 1991 and 1999. Preoperatively 316 (68%) patients were in New York Heart Association class III or IV. There were 417 (85%) aortic, 61 (12%) mitral, 13 (2.6%) aortic and mitral, and two (0.4%) tricuspid procedures. Concomitant procedures were performed in 163 (33%) patients. Follow-up was complete in 488 (98.9%) patients with a total cumulative follow-up of 1,402 patient-years. RESULTS: The 30-day mortality in this elderly population was 10% (95% confidence interval, 8 to 13), with no early valve-related deaths. Patients' survival at 8 years was 46% +/- 7%. This was influenced by the following factors: (1) the patient's age, being worse for those 70 years or older (p = 0.005); (2) those in New York Heart Association functional class III and IV (p = 0.004); (3) those in atrial fibrillation before the operation (p = 0.006); (4) those with poor left ventricular function (p = 0.009); and (5) those who had a previous cardiac operation (p = 0.003). Valve-related complications (expressed as percent per patient-year) were thromboembolism at 0.9%/patient-year; major hemorrhage at 1.4%/patient-year; bacterial endocarditis at 0.4%/patient-year; nonstructural dysfunction at 0.2%/patient-year, and reoperation at 0.2%/patient-year. At 8 years, freedom from thromboembolism was 93% +/- 7%, major hemorrhage, 90% +/- 4%, nonstructural dysfunction, 99% +/- 1%, structural valve failure, 100%, and reoperation, 99% +/- 1%. At follow-up, 98% of survivors were in New York Heart Association class I or II. CONCLUSIONS: Our study suggests that at 8 years, the Tissuemed (Aspire) porcine bioprosthesis is durable and has satisfactory performance with low complication rates.

Intraoperative and laboratory evaluation of skeletonized versus pedicled internal thoracic artery.

BACKGROUND: The skeletonization of internal thoracic artery is postulated to improve graft length, early blood flow, sternal blood supply, and postoperative respiratory function. Concern exists that skeletonization may injure internal thoracic artery, precluding good results of surgery. Reports on endothelial function of skeletonized internal thoracic artery are lacking. METHODS: A prospective assessment of early clinical outcomes of 357 consecutive patients undergoing coronary artery bypass grafting was performed: 287 patients with nonskeletonized and 70 with skeletonized left internal thoracic artery (LITA). The lengths of LITA and of its discarded distal segment, as well as free LITA blood flow, were measured. The dose-effect relationship for relaxation to acetylcholine was studied in the organ bath. RESULTS: Apart from a higher incidence of breaching the pleura with nonskeletonized LITA the clinical outcomes were comparable. The length of skeletonized LITA was 17.8+/-1.14 cm versus 20.3+/-0.52 cm skeletonized (p = 0.11). The length of discarded LITA was shorter in nonskeletonized artery (0.8+/-0.28 cm versus 2.6+/-0.49 cm; p = 0.022). The free LITA blood flow was 66.3+/-7.42 mL/min in nonskeletonized vessel versus 100.3+/-14.84 mL/min in skeletonized (p = 0.048). The acetylcholine-induced relaxation was similar in both groups (maximal relaxation, 80.7%+/-5.95% in nonskeletonized versus 72.9%+/-9.11% in skeletonized; not significant; negative logarithm of half-maximal effect, 7.43+/-0.18 versus 7.1+/-0.10, respectively; p = 0.063). CONCLUSIONS: Skeletonization does not damage the endothelial function of the LITA. Higher free blood flow and available LITA length should encourage the use of skeletonized LITA in clinical practice.

A multi-centre randomised controlled trial of minimally invasive direct coronary bypass grafting versus percutaneous transluminal coronary angioplasty with stenting for proximal stenosis of the left anterior descending coronary artery.

OBJECTIVES: To compare the clinical- and cost-effectiveness of minimally invasive direct coronary artery bypass grafting (MIDCAB) and percutaneous transluminal coronary angioplasty (PTCA) with or without stenting in patients with single-vessel disease of the left anterior descending coronary artery (LAD). DESIGN: Multi-centre randomised trial without blinding. The computer-generated sequence of randomised assignments was stratified by centre, allocated participants in blocks and was concealed using a centralised telephone facility. SETTING: Four tertiary cardiothoracic surgery centres in England. PARTICIPANTS: Patients with ischaemic heart disease with at least 50% proximal stenosis of the LAD, suitable for either PTCA or MIDCAB, and with no significant disease in another vessel. INTERVENTIONS: Patients randomised to PTCA had local anaesthetic and underwent PTCA according to the method preferred by the operator carrying out the procedure. Patients randomised to MIDCAB had general anaesthetic. The chest was opened through an 8-10-cm left anterior thoracotomy. The ribs were retracted and the left internal thoracic artery (LITA) harvested. The pericardium was opened in the line of the LAD to confirm the feasibility of operation. The distal LITA was anastomosed end-to-side to an arteriotomy in the LAD. All operators were experienced in carrying out MIDCAB. MAIN OUTCOME MEASURES: The primary outcome measure was survival free from cardiac-related events. Relevant events were death, myocardial infarction, repeat coronary revascularisation and recurrence of symptomatic angina or clinical signs of ischaemia during an exercise tolerance test at annual follow-up. Secondary outcome measures were complications, functional outcome, disease-specific and generic quality of life, health and social services resource use and their costs. RESULTS: A total of 12,828 consecutive patients undergoing an angiogram were logged at participating centres from November 1999 to December 2001. Of the 1091 patients with proximal stenosis of the LAD, 127 were eligible and consented to take part; 100 were randomised and the remaining 27 consented to follow-up. All randomised participants were included in an intention-to-treat analysis of survival free from cardiac-related events, which found a non-significant benefit from MIDCAB. Cumulative hazard rates at 12 months were estimated to be 7.1 and 9.2% for MIDCAB and PTCA, respectively. There were no important differences between MIDCAB and PTCA with respect to angina symptoms or disease-specific or generic quality of life. The total NHS procedure costs were 1648 British pounds and 946 British pounds for MIDCAB and PTCA, respectively. The costs of resources used during 1 year of follow-up were 1033 British pounds and 843 British pounds, respectively. CONCLUSIONS: The study found no evidence that MIDCAB was more effective than PTCA. The procedure costs of MIDCAB were observed to be considerably higher than those of PTCA. Given these findings, it is unlikely that MIDCAB represents a cost-effective use of resources in the reference population. Recent advances in cardiac surgery mean that surgeons now tend to carry out off-pump bypass grafting via a sternotomy instead of MIDCAB. At the same time, cardiologists are treating more patients with multi-vessel disease by PTCA. Future primary research should focus on this comparison. Other small trials of PTCA versus MIDCAB have now finished and a more conclusive answer to the original objective could be provided by a systematic review.

Signal averaged P wave compared with standard electrocardiography or echocardiography for prediction of atrial fibrillation after coronary bypass grafting.

OBJECTIVE: To define the clinical value of the signal averaged P wave (SAPW) and to compare it with the standard electrocardiogram (ECG), echocardiogram, and clinical assessment for the prediction of atrial fibrillation after coronary bypass grafting (CABG). DESIGN: Prospective validation cohort study. SETTING: Regional cardiothoracic centre. PATIENTS: 201 unselected patients undergoing first elective CABG were recruited over six months. Patients requiring concomitant valve surgery were excluded. MAIN OUTCOME MEASURES: Age, sex, cardiothoracic ratio, and cardioactive drugs were noted. P wave specific SAPW recordings, ECG, and M mode echocardiograms from which left atrial diameter was measured were performed within 24 hours of surgery. Filtered P wave duration (SAPWD), spatial velocity, and energy were calculated from the SAPW. From the ECG, lead II P wave duration, P terminal force in lead V1, total P wave duration, and isoelectric interval were measured. Patients had Holter monitoring for 48 hours postoperatively and daily ECGs until discharge. RESULTS: Two patients died (1%) and 10 were unsuitable for analysis (5%). Of the remaining 189, 51 (27%) had atrial fibrillation (AF) lasting > 1 hour at a mean of 2 (0.5 to 7) days after CABG. Of the variables examined, only SAPWD (AF group 148 (SD 12), v 142 (14) ms, P = 0.008) and male sex (AF group 96%, v 78%, P < 0.01) were significantly different. A prospectively defined SAPWD of > 141 ms predicted atrial fibrillation with positive and negative predictive accuracies of 34% and 83%. Logistic regression analysis identified both male sex and SAPWD as significant independent predictors of postoperative atrial fibrillation. CONCLUSIONS: Signal averaged P wave duration was a better predictor of atrial fibrillation after coronary bypass grafting than standard electrocardiographic or echocardiographic criteria. The predictive value of this test is such that it is likely to be useful in the design of prospective trials of prophylactic antiarrhythmic treatment but is of limited use using current techniques in the clinical management of individual patients.

Residual atrial fibrillation and clinical consequences following postoperative supraventricular arrhythmias.

AIMS: This retrospective study investigated whether the supraventricular arrhythmias (SVA) observed during cardiac surgery are limited to or persist beyond the postoperative period, their clinical consequences and whether they are influenced by preoperative and postoperative factors. METHODS: A total of 375 patients undergoing elective bypass graft surgery over a 15-month period by three surgeons were included. All patients had their preoperative medications continued to the day of surgery and prophylactic anti-arrhythmic medications were not used in any of the cases. Standard anaesthetic techniques were used. Rhythm disturbances were diagnosed by ECG. The arrhythmias were treated medically or by cardioversion. All patients were followed up for 6 months. RESULTS: Postoperative SVA occurred in 25% of patients. The commonest arrhythmia was atrial fibrillation (89.4%), followed by atrial flutter (6.4%) and supraventricular tachycardia (4.2%). In 89. 8% of the cases, the arrhythmias occurred within the first four postoperative days with a maximum incidence on the second day (27. 7%). Atrial fibrillation was still present in 50% of patients at hospital discharge and in 39% at 6 months follow up. Patients with arrhythmias had a prolonged hospital stay (7.7+/-2.6 vs. 6.0+/-2.6 days; P<0.05). There was no hospital mortality in the study and the incidence of postoperative stroke was equal in the sinus rhythm and arrhythmia patients (1.1%). SVA were more frequent when cardioplegia was used to protect the heart (32%) than with intermittent ischaemia (9%; P<0.001). At 6 months follow up, the patients receiving cardioplegia also had a higher prevalence of atrial fibrillation than those operated with intermittent ischaemia (41% vs. 22%; P<0. 05). The incidence of SVA and persistence of atrial fibrillation was unrelated to other preoperative and intraoperative factors. CONCLUSION: Postoperative supraventricular arrhythmias have a long-lasting effect on cardiac rhythm: patients with SVA have a high probability of remaining in atrial fibrillation at hospital discharge and 6 months after surgery. The occurrence of atrial fibrillation seems to be influenced by the type of myocardial protection used but this does not appear to exert harmful effects.

Preoperative and early postoperative assessment of the internal thoracic artery by transcutaneous duplex ultrasound in coronary artery bypass grafting.

We examined internal thoracic artery by transcutaneous duplex ultrasound in 26 patients on four occasions: 4 (+/-2) days before the operation, and 61 (+/-8) minutes, 5 days and 53 (+/-3) days postoperatively. There was dominant systolic flow in preoperative scans. After the operation a characteristic biphasic flow with increased peak diastolic velocity and a decrease in peak systolic/peak diastolic velocity ratio was detected in all patients. The pulsed Doppler spectrum was used to measure peak velocity, time averaged mean velocity and time averaged maximum velocity. Resting internal thoracic artery flows calculated using time averaged mean velocity were 30.9+/-5.4 ml/min preoperatively, 40.7+/-6.3 ml/min immediately after surgery, 41.1+/-8.2 ml/min at 5 days and 40.1+/-4.9 ml/min at 53 days. There were no significant changes in resting internal thoracic artery flow between early and late postoperative studies. Flow estimates calculated using 0.5 x time averaged maximum velocity or time averaged mean velocity showed good agreement. Early postoperative measurements appear to be a good predictor of later resting graft flow.

Chronic haemoptysis as delayed complication of ventricular aneurysmectomy.

Two patients developed a ventriculo-pulmonary fistula several years after original resection of a left ventricular aneurysm. Both presented with chronic mild haemoptysis. In the first case mild haemoptysis lasted nearly 19 months, and despite a battery of non invasive and invasive investigations, diagnosis was ultimately made via exploratory thoracotomy. In the second case mild haemoptysis lasted four months and finally manifested as a large haemoptysis. Diagnosis was made preoperatively using echocardiography. We recommend the use of echocardiography when haemoptysis occurs in a patient with a previous history of ventricular aneurysm repair.

Severe haemolysis with the St. Jude Medical prosthesis.

The St. Jude Medical prosthesis has become one of the most widely used mechanical heart valves because of its excellent haemodynamic function. Although subclinical haemolysis has been described with this prosthesis, there has only been a single report of frank haemolysis in the absence of a paravalvular leak. We report the occurrence of severe haemolysis in five patients following St Jude Medical prosthesis implantation, four of whom had combined aortic and mitral valve replacements. In no patient could the haemolysis be attributed either to a paravalvular leak or an obvious valve malfunction.

Clinical evaluation of the Björk-Shiley disc valve in the tricuspid position. Long-term results.

Between 1971 and 1981, 1210 Björk-Shiley prostheses were implanted. Of these, 79 were in the tricuspid position, comprising 30 triple valve replacements, 46 mitral plus tricuspid, and 3 isolated tricuspid replacements. The ages ranged from 10-55 years (mean 45 years). Sixty-three patients (80%) were in NYHA grades III or IV preoperatively. Thirteen patients died in hospital after surgery (16.5%). The 66 survivors have been followed for up to 16 years (mean 7.5 years). There have been 37 late deaths (7.5 per patient year). Twelve were valve-related: 4 tricuspid complications, 4 mitral complications, 2 prosthetic endocarditis, 1 aortic leak and 1 anticoagulant-related bleed. Twenty-one late deaths were not valve-related, and 4 causes of death are unknown. Expressed actuarially, survival at 5 years was 68%, and at 10 years, 49.4% +/- 12%. Freedom from valve-related death at 10 years was 80.7% +/- 7%. At last follow-up, 90% of the survivors were in NYHA class 1 or 2 with only modest signs of venous hypertension. The commonest life-threatening complication was obstruction of the tricuspid prosthesis by tissue ingrowth. This occurred in 7 patients (1.4% per patient year) 4 were re-operated upon and survived, 3 died. Doppler echocardiography has been carried out on 27 survivors of whom 5 had abnormal pressure-half times but only 3 of these were symptomatic. This series shows that function of the standard disc Björk-Shiley prosthesis in the tricuspid position compares favourably with other prostheses. The problem of tissue ingrowth can be diagnosed by echo Doppler and reoperation successfully carried out.

Protective influence of pretreatment with allopurinol on myocardial function in patients undergoing coronary artery surgery.

Xanthine oxidase is responsible for the release of free oxygen radicals during myocardial reperfusion. Allopurinol was shown to be an effective inhibitor of this reaction in the laboratory experiments, but not in patients. Thirteen male patients undergoing routine coronary artery bypass graft surgery were treated with allopurinol in doses of 15 mg/kg per day for 4 days before the operation. Haemodynamic function in the early period after cardiopulmonary bypass, ECG, enzyme release and ultrastructural findings in this group were compared with those in a control group of 13 male patients matched for age distribution and stage of coronary disease. Left ventricular stroke work index was higher in the treatment group 10 min (P less than 0.001) and 15 min after termination of cardiopulmonary bypass (P less than 0.01) and also 2 h later (P less than 0.02). In the early post-operative recovery phase fewer episodes of arrhythmia were observed in this group of patients (P less than 0.001). Electron microscopy studies of the myocardium and CK and CK-MB release showed no significant differences between groups. Thus, allopurinol may have a protective effect on the human ischaemic myocardium in the early period of reperfusion.

Carbomedics and St. Jude Medical bileaflet valves: an in vitro and in vivo comparison.

The hydrodynamic and haemodynamic function of 29 mm mitral and 23 mm aortic St Jude Medical (SJM) and CarboMedics (CM) heart valves have been compared in a pulsatile flow simulator in the laboratory and by doppler ultrasound in vivo. The laboratory studies showed that there was no significant difference in the pressure drop across the valves. The valves also had similar regurgitant volumes. Doppler ultrasound confirmed these results with a mean pressure drop of 12.9 +/- 5.5 mmHg across the CM aortic valves and 12.6 +/- 5.5 mmHg for the SJM aortic valves. The mean mitral diastolic pressure drops were 3.8 +/- 1.8 and 4.6 +/- 1.4 mmHg for the CM and SJM valves, respectively. Mild aortic regurgitation was detected in 5 of 14 patients in the CM group and 1 out of 6 patients in the SJM group, though none of the cases were clinically significant. Both the in vitro and in vivo results show these valves to have acceptable and comparable function.