Alan R. Kerr

Long-Term Survival and Valve-Related Complications in Young Women With Cardiac Valve Replacements

BACKGROUND The type of cardiac valve replacement associated with the lowest health risks for young women who may undergo pregnancies is unknown. We investigated which valve type was associated with greatest patient and valve survival and the effect of pregnancy on valve loss. METHODS AND RESULTS In this retrospective study, all women 12 to 35 years old who underwent valve replacements between 1972 and 1992 at Greenlane Hospital were identified, and follow-up was available in 93%. The 232 women were followed up for 1499 patient-years. Ten-year survival of women with mechanical (n=178), bioprosthetic (n=73), and homograft (n=72) valves was 70% (95% CI, 59% to 83%), 84% (95% CI, 72% to 99%), and 96% (95% CI, 91% to 100%), P=0.002. After adjustment for confounding variables, the relative risk (RR) of death with mechanical compared with bioprosthetic valves was 2.17 (95% CI, 0.78 to 5.88). Thromboembolic events occurred in 45% of women with mechanical valves within 5 years, compared with 13% with bioprosthetic valves, P=0.0001. Valve loss at 10 years was higher in bioprosthetic valves [82% (95% CI, 62% to 92%)] than in mechanical [29% (95% CI, 17% to 39%)] or homograft [28% (95% CI, 12% to 41%)] valves, P=0.0001. Pregnancy was not associated with increased bioprosthetic (RR, 0.96; 95% CI, 0.68 to 1. 35), homograft (RR, 0.65; 95% CI, 0.37 to 1.13), or mechanical (RR, 0.54; 95% CI, 0.27 to 1.08) valve loss. CONCLUSIONS Although 10-year valve survival was greater with mechanical than bioprosthetic valves, mechanical valves may be associated with reduced patient survival in young women. Thromboembolic complications, often with long-term sequelae, were common with mechanical valves. Pregnancy did not increase structural deterioration or reduce survival of bioprosthetic valves.

Prosthetic repair of coarctation of the aorta with particular reference to Dacron onlay patch grafts and late aneurysm formation.

Prosthetic material was used in the repair of coarctation of the aorta in 72 patients followed for 8 months to 24 years after operation. False aneurysms occurred late postoperatively in 1 of 17 instances when a tube graft was used to replace the resected aorta and in 1 of 2 patients when the graft bypassed the obstructed area. A Dacron onlay patch graft (DOPG) was used in 52 patients as the primary method of repair, to revise a previous repair or as an adjunct to another procedure at the time of initial operation. True or false late aneurysm occurred between 6 and 18 years postoperatively in 5 of the 38 patients in whom a DOPG was used for primary repair of the coarctation or to revise an earlier repair, an actuarial incidence of 38% at 14 years. Diagnosis of aneurysm formation late postoperatively depends on awareness of this complication and careful assessment of lateral as well as posteroanterior chest radiographs. DOPG should be avoided whenever possible.

Coronary surgery after recurrent myocardial infarction: progress of a trial comparing surgical with nonsurgical management for asymptomatic patients with advanced coronary disease.

A randomized trial of surgical vs nonsurgical management was carried out in men 60 years of age or younger who had recovered from a recurrent myocardial infarction. Of 205 patients considered, 100 had few or no symptoms and had coronary vessels favorable for bypass grafting; these patients fulfilled the trial conditions and were randomized (50 surgical and 50 nonsurgical). In 41 patients (elective nonsurgical group), randomization was not considered justifiable because of relatively unfavorable coronary anatomy or severe left ventricular dysfunction. Nineteen patients had elective surgery because of disabling angina despite full medical treatment or because of significant left main coronary stenosis. In 45 patients, coronary angiography was not undertaken because of medical contraindications or reluctance of the patient to enter the study.Actuarial survival curves (mean follow-up 4.5 years) show an annual mortality rate of 3–4% per year for all investigated patients, and no advantage for the randomized surgical over the randomized nonsurgical group. The results suggest that in the absence of disabling angina or left main coronary artery stenosis, coronary artery surgery need not be advised for survivors of recurrent infarctions who have severe coronary artery disease. Moreover, the prognosis for the group of patients not treated surgically appears to be better than has been previously described.

Ultrasonic imaging of the coronary arteries in open-chest humans: evaluation of coronary atherosclerotic lesions during cardiac surgery.

We explored techniques that would allow the surgeon to localize coronary artery lesions demonstrated angiographically or to supplement angiographic information in patients who are undergoing coronary artery bypass procedures by intraoperative scanning of the coronary arteries using ultrasound. A 9-MHz electronically focused water-path ultrasound scanner was first used to image the coronary arteries in three anesthetized, open-chest sheep. In a subsequent study, 10 human subjects undergoing cardiac surgery for valve replacement who had normal coronary angiograms were scanned during heart surgery to provide images of normal coronary arteries. The ultrasoundprobe was sterilized with gas and placed directly on the beating heart by the surgeon. In the third phase of this study, 21 patients with coronary artery disease were scanned and the ultrasonic appearance of their imaged coronary lesions was compared to independently interpreted angiographic estimates of percent obstruction, with close correlation (r = 0.91). The ultrasound scan could be used to identify lesions in vessels beyond proximal occlusions, which are not visualized well angiographically, and could localize thesite of lesions to determine placement of saphenous vein bypass grafts. This new technique may provide a method of evaluating coronary atheroscleroticlesions during coronary artery surgery and aid decisions regarding placement of saphenous vein grafts.

Gram Stain, Culture, and Histopathological Examination Findings for Heart Valves Removed because of Infective Endocarditis

Retrospective chart review was undertaken for 480 patients who underwent a total of 506 valve replacements or repair procedures for infective endocarditis. The influence of preoperative antimicrobial treatment on culture, Gram stain, and histopathological examination findings for resected valve specimens was examined. When valves were removed before the end of treatment, organisms were seen on the Gram stain of ground valve material performed in the microbiology laboratory and on Gram-stained histopathological sections in 231 (81%) of 285 and 140 (67%) of 208 specimens, respectively (P=.0007). Gram-positive cocci were either cultured from or observed in excised valve tissue in 42 (67%) of 63 episodes involving negative preoperative blood cultures. Positive Gram stain results for microbiological specimens should be reintroduced into the definite pathological criteria for infective endocarditis. When deciding on how long to continue antimicrobial therapy after valve replacement for endocarditis, valve culture results should be the only laboratory finding taken into account, because it takes months for dead bacteria to be removed from sterile vegetations.

Assessment and follow-up of patients with ventricular septal defect and elevated pulmonary vascular resistance

Cardiac catheterization was undertaken in 87 patients (for a total of 89 studies) with ventricular septal defects, including 58 patients with moderate or severe elevation of pulmonary arteriolar resistance. When resting resistance was less than or equal to 7.9 U . m2, it always decreased with isoproterenol and no postoperative problems were experienced with pulmonary vascular obstructive disease. In 36 patients resting resistance measured greater than or equal to 8 U . m2. In 17 of these patients it decreased to less than 7 U . m2 with isoproterenol. Fifteen patients were operated on and postoperative problems with pulmonary vascular disease were experienced only in the single patient whose repair broke down. Surgery was undertaken in 4 of 19 patients in whom resistance did not decrease to less than 7 U . m2 with isoproterenol and advanced pulmonary vascular disease was evident in the 3 patients with follow-up observation. Correlation between measured resistance and other hemodynamic parameters was only fair. A pulmonary to systemic resistance ratio greater than or equal to 0.75 always indicated high absolute resistance but resistance ratios less than 0.75 were found quite frequently in the group with limited response to isoproterenol. These data argue that a reliable estimate of resistance, less than 7 U . m2, with a vasodilator predicts a good postoperative response regardless of measurements at rest or other hemodynamic parameters. Although observations on postoperative progress of patients with resistance greater than 7 U . m2 with a vasodilator are limited, a good postoperative course is unlikely unless resistance can be lowered to a level close to 7 U . m2.

Bacteriological Outcome after Valve Surgery for Active Infective Endocarditis: Implications for Duration of Treatment after Surgery

BACKGROUND There has been no systematic evaluation of outcome after surgery for infective endocarditis with respect to duration of antibiotic treatment. METHODS We performed a retrospective chart review of episodes of valve surgery for active infective endocarditis at Green Lane Hospital (Auckland, New Zealand) for 1963-1999. We recorded the duration of antibiotic treatment before and after valve surgery; the extent of infection at operation; Gram stain, culture, and histopathological testing results for valve samples; and the bacteriological outcome after surgery. The primary outcome measure was relapse, defined as endocarditis due to the same species within 1 year after surgery. RESULTS For the 358 patients in our study, the median duration of follow-up was 4.8 years. Thirty-two patients (9%) had 36 subsequent episodes of endocarditis. Relapse occurred after 3 (0.8%) of the operations (95% CI, 0.2%-2.0%). Relapse of infection was unrelated to the duration of antibiotic treatment before or after surgery, positive valve culture results, positive Gram stain results, or perivalvular infection. Since 1994, we have reduced the duration of antibiotic treatment by approximately 7 days for those with positive valve culture results and by approximately 14 days for those with negative valve culture results, without any increase in the number of relapses. CONCLUSIONS Relapse is an uncommon event following surgery for endocarditis. Commonly suggested indications for prolonging postoperative treatment are not associated with higher relapse rates, and their relevance is debatable. We conclude that it is unnecessary to continue treatment for patients with negative valve culture results for an arbitrary 4-6-week period after surgery. Two weeks of treatment appears to be sufficient, and, for those operated on near the end of the standard period of treatment, simply completing the planned course should suffice.

Extracardiac conduit with a limited maze procedure for the failing Fontan with atrial tachycardias

BACKGROUND Atrial arrhythmias are a frequent late complication of Fontan procedures. Conversion to an extracardiac conduit combined with reducing right atrial size should improve hemodynamics and reduce the development of tachyarrhythmias. More effective control may be achieved by interrupting atrial arrhythmia circuits and atrial pacing. METHODS Between May 1997 and October 2001, 6 patients underwent a revision of their intracardiac Fontan anastomosis. The conversion included an extracardiac conduit insertion, limited right atrial maze procedure, and pacemaker placement. Ages ranged from 14 to 34 years (mean, 22.8 years) at an average of 14.6 +/- 4.4 years after their original Fontan procedure. All of the patients had medically uncontrollable atrial tachyarrhythmias with markedly reduced exercise tolerance. RESULTS All of the patients survived with an average hospital stay of 16.7 days. Exercise tolerance has improved in all 6 patients, and atrial tachycardias have either decreased (n = 2) or disappeared (n = 4). Two patients are taking antiarrhythmic medications other than digoxin. Follow-up is a mean of 28.5 months. CONCLUSIONS Limited right atrial maze procedure, atrial size reduction, and pacemaker implantations are worthwhile additions to simple conversion to an extracardiac conduit in the failing Fontan.

Late Outcome After Coronary Artery Bypass Graft Surgery in Patients <40 Years Old

BACKGROUND Randomized trials confirm the long-term efficacy of coronary artery bypass graft surgery (CABG), although there are no randomized data in patients < 40 years old. Because these patients have been reported to have an early recurrence of symptoms, the long-term postoperative outcome was examined. METHODS AND RESULTS The long-term outcome of patients (n = 221) < 40 years old undergoing CABG at Green Lane Hospital, New Zealand, from 1970 to 1992 was determined. The 30-day mortality rate was 1.8% for initial and 9.5% for redo CABG. The median times to angina or myocardial infarction (recurrent ischemic event), further intervention, and death were 6.0, 9.6, and 14.2 years, respectively. Factors associated with increased late mortality on univariate analysis included end-systolic volume (ESV) > or = 80 mL (P = .004; 10-year mortality 19% versus 39% ESV > or = 80 mL), no internal mammary conduit (P = .01), no lipid-modifying therapy (P = .005), and no postoperative aspirin use (P = .0002); the latter was also associated with increased recurrent ischemic events (P = .04) or increased reintervention (P = .02). On stepwise logistic regression analysis, factors associated with increased late mortality were increasing ESV (P = .004), no internal mammary artery conduit (P = .009), diabetes (P = .04), and no postoperative aspirin (P = .02); the latter was also associated with increased recurrent ischemic events (P = .02). Hypercholesterolemia (> or = 6.5 mmol/L) was present in 65% of patients at presentation and 45% at follow-up. CONCLUSIONS To attempt to prevent recurrent ischemia or late death, patients < 40 years old who require CABG should receive internal mammary conduits, aspirin, lipid-modifying therapy, therapy to inhibit ventricular dilatation, and strict diabetes management.

Coronary revascularisation in young adults

OBJECTIVE To evaluate the long-term outcome of coronary artery bypass surgery (CABG) in patients < 40 years old and to determine factors predictive of adverse outcomes. METHODS Retrospective review of data on 220 patients who underwent isolated CABG at Green Lane Hospital, New Zealand from 1970 to 1992. RESULTS The actuarial survival after surgery was 91, 74 and 50% at 5, 10 and 15 years, respectively. Recurrence of ischaemic symptoms occurred at a median time of 72 months, and only 20% of patients remained asymptomatic 10 years after CABG. Univariate analysis of potentially adverse surgical factors showed that patients who had prolonged bypass time (> or = 100 min, P < 0.007) had increased late mortality. There were two distinct operative eras with respect to the use of IMA conduits (4% pre 1985, 87% post 1984) The relationship between IMA conduits use and survival was significant on time independent analysis (P < 0.02), but was not using the log-rank test. Preoperative clinical characteristics associated with increased late mortality were impaired left ventricular function (end-systolic volume (ESV) > or = 80 ml, P = 0.008; ejection fraction < 40%, P = 0.0005), and lack of aspirin use either pre- or post-operatively (P < 0.0001). Multivariate analysis indicated that reduced ejection fraction (P = 0.04) and prolonged bypass time (P = 0.05) was associated with an increased risk of late death. Aspirin therapy (P = 0.001) was associated with decreased late mortality. Cumulative events rate of reintervention and mortality was reduced in female patients (P = 0.0009). At review, 45% of patients had total cholesterol > 6.5 mmol/l. CONCLUSION To avoid the early recurrence of symptoms, the need for reintervention and late mortality, young patients should receive IMA conduits, cardioplegia as myocardial protection, aspirin and therapy to modify/ameliorate their risk factors including dyslipidaemia, diabetes and left ventricular dysfunction.