Six-year follow-up of the Toronto stentless porcine valve.

Stentless valves in the aortic position have been shown to have superior hemodynamic performance to stented valves and have now been shown to increase survival. We report the medium-term results from a single center of 229 Toronto (SPV) aortic valve replacements between 1994 and 2000. The mean age of the patients was 72 years (range, 41-87 years). The mean Euroscores were 6.2 (+/-0.13) and Parsonnet scores of 16.8 (+/-0.5). Concomitant coronary artery bypass grafting was performed in 125 (55%) of patients, eight patients had additional mitral valve replacements and ten were redo procedures. Hospital mortality was 3.5%. The mean follow-up period was 45 (7-81) months. The actuarial survival was 92.4% (+/-1.4%) at one year and 76.2% (+/-3.5%) at five years. There were 37 late deaths (4.7% per patient years). There were 3 patients with prosthetic valve endocarditis (0.38% per patient years), two of whom died. Stroke occurred in 13 patients (1.6% per patient years), five of whom died. None of these events were known to be valve related. There was no incidence of structural valve dysfunction and no valves have been explanted. At follow-up, the mean transvalvular gradient was 4.2 mm Hg (range, 0.9-12.7 mm Hg). No aortic incompetence (AI) was seen in 88% of patients with trivial or mild AI in 11% of patients and moderate AI in one patient. This series shows acceptable early and medium-term results in an elderly population with a high incidence of coronary artery disease.

Ventricular remodelling and revascularization in severe left ventricular dysfunction.

OBJECTIVE: To evaluate the role of surgical revascularization in the presence of severe, global impairment of left ventricular function without discrete aneurysm formation or mitral regurgitation. The high mortality and morbidity associated with this group, together with the limited benefits tend to prompt referral for cardiac transplantation. METHODS: Fifty-three patients initially referred for transplantation, in addition to coronary revascularization, underwent mitral annuloplasty (group A = 23), free wall remodelling by endoaneurysmorrhaphy (group B = 17) or mitral annuloplasty and free wall reconstruction (group C = 13). The mean ages were 59, 56 and 57 years for groups A, B and C, respectively. Detailed assessment of pre- and post-operative physical and psychological status were carried out. RESULTS: Follow-up was for a mean period of 22-26 months. All patients reported substantial improvement in quality of life, both physical and psychological parameters and in NYHA functional class status. Objective evidence of improvement in ejection fraction was seen in all three groups but especially in group A. There were five early deaths, four were due to inadequate revascularization due to the poor quality of target vessels. There were three late deaths and one patient that required transplantation. CONCLUSION: We conclude that patients with severe left ventricular dysfunction can be candidates for surgical revascularization and optimization of ventricular geometry with acceptable mortality. The importance of achieving complete revascularization is emphasized in this series.

Alterations in renal microcirculation during cardiopulmonary bypass.

BACKGROUND: This study was designed to investigate renal microvascular changes during cardiopulmonary bypass. METHODS: Kidneys were harvested from each of four groups of 6 pigs. Group A were anesthetized and heparinized only. The remaining three groups underwent cardiopulmonary bypass at 28 degrees C, group B for 30 minutes and groups C and D for 120 minutes; group D had an additional 30 minutes of normothermic perfusion at the end of the experiment. Renal cortical blood flow was measured using radiolabeled microspheres. Microvascular morphology was defined by corrosion casting and scanning electron microscopy. RESULTS: In group A, renal vascular resistance was 61+/-5.1 mm Hg x mL(-1) x min(-1). This value decreased to 28+/-7.8 in group B and 25+/-4.0 in group C (p < 0.05), and increased in group D to 40+/-4.1 (p < 0.05 versus groups A, B, and C). Cortical thickness, as measured by microvascular casts in groups A, B, and C, was 33, 34, and 31 mm, respectively, with equal distribution of the resin to the superficial and deep cortex but was significantly reduced in group D to 22 mm (p < 0.05 versus groups A, B, and C), with failure of the resin to fill the superficial cortical layer. Diameters of glomeruli as seen on the casts were 111+/-10.38 microm in group A, 100+/-9.24 microm in group B, and 82+/-4.4 microm in group C (p < 0.05 group A versus group C). The glomeruli from group D were still significantly smaller than group A (93+/-10.35 microm, p < 0.05). Mean glomerular capillary diameters were 4.65+/-0.26 microm in group A, 3.9+/-0.16 microm in group B, 3.6+/-0.19 microm in group C, and 3.65+/-0.3 microm in group D (p < 0.05 group A versus groups B, C, and D). CONCLUSIONS: Hypothermic nonpulsatile cardiopulmonary bypass decreased renal vascular resistance, but the superficial and deep layers of the cortex were perfused equally. Glomeruli were reduced in size because of capillary narrowing. This was consistent with diversion of blood through bypass channels. With restoration of normothermia, underperfusion of the superficial cortex occurred, with potential for damage to these nephrons during the increased metabolic demands of rewarming.

Osteonecrosis of the calcaneum in a heart transplant recipient.

Avascular necrosis affects 3% of transplant recipients. In the lower limb, the femoral heads or condyles may be involved. We report the hitherto unrecorded complication of avascular necrosis of the calcaneum. Conservative management resulted in resolution without long-term complications.

Back from the dead: extracorporeal rewarming of severe accidental hypothermia victims in accident and emergency.

Severe accidental hypothermia in an urban environment is usually associated with drug or alcohol abuse or serious illness in elderly or debilitated patients. In the presence of cardiovascular instability, extracorporeal rewarming by cardiopulmonary bypass is the gold standard of treatment of such patients. Three cases of profound hypothermia with circulatory collapse are presented. Each was successfully resuscitated to a full neurological recovery using this method in an accident and emergency (A&E) department, although one died later of respiratory complications. All three cases had a serum potassium in the normal range at the start of treatment. Where facilities exist, extracorporeal rewarming can be performed in A&E for patients with profound hypothermia and circulatory collapse. Cardiopulmonary resuscitation must be continued throughout the rewarming process.

Marfanoid aneurysm in donor aorta after transplantation.

A case is reported of dissecting aneurysm of the donor ascending aorta and root 4 years after orthotopic cardiac transplantation. The pathology raises the possibility of Marfan's syndrome in the donor.

Left atrial myxoma in a preschool child.

A case of left atrial myxoma successfully removed using cardiopulmonary bypass in a 5-year-old child is presented. Review of the literature emphasizes the rarity and clinically aggressive behavior of this tumor in this age group.

The effects of cardioplegic arrest and reperfusion on the microvasculature of the heart.

OBJECTIVES: Despite laboratory evidence of leucocyte involvement in reperfusion injury, cardiac surgical clinical trials do not support the therapeutic effectiveness of leucocyte filtration. Furthermore, the direct effects of crystalloid cardioplegia and reperfusion on the capillaries of the heart have yet to be elucidated. We tested the effects of cardioplegic arrest and reperfusion both with and without leucocyte depletion, in a model of cardiopulmonary bypass that mimics clinical cardiac surgical conditions. METHODS: Four groups of Landrace pigs were studied. Group A (n = 6) underwent 30 min of hypothermic (28 degrees C) cardiopulmonary bypass. Groups B (n = 6), C (n = 6) and D (n = 6) also had 90 min of cardioplegic arrest. Group C was then reperfused with whole blood, while Group D was reperfused with leucocyte-depleted blood. Microvascular methylmethacrylate corrosion casts were made at the end of the experimental period. Myocardial vascular anatomy was defined by electron microscopy and capillary abundance derived from this and from the weight of casts from representative areas. Leucocyte deposition was assessed using radioisotope-labelled leucocytes. Ischaemic damage to tissues was graded according to light and electron microscopic findings. RESULTS: In Group A the mean (+/- S.D.) vascular cast weight/volume of myocardium (density) was 125 +/- 9 mg/mm3. After cardioplegic arrest (Group B), it fell to 74 +/- 7 mg/mm3 (P < 0.0001) due to absence of capillaries, although arterioles, venules and non-nutritive bypass vessels remained patent. Following reperfusion with whole blood (Group C), capillary numbers partially recovered but luminal diameters were reduced with a cast density of 94 +/- 5 mg/mm3 (P < 0.0001 versus Group A and B). Leucocyte-depleted (87-92%) reperfusion in Group D did not affect cast density (90 +/- 3 mg/mm3; P = 0.17). Coronary vascular resistances in Groups C and D rose slightly, but not significantly, during reperfusion. CONCLUSIONS: Following cardioplegic arrest, microvascular changes are marked. These changes are partially reversed by 30 min reperfusion. Leucocyte depletion does not ameliorate these effects in this model.

Emergency bypass without bypass!

We present 2 cases of failed coronary angioplasty, with hemodynamic compromise, where emergency coronary artery bypass grafting was performed without cardiopulmonary bypass. The hypodynamic nature of the stunned myocardium in this circumstance allows this technique to be applied with relative ease to accessible vessels. As a consequence, reduced morbidity and hospital stay can be anticipated.

Acute-phase responses to cardiopulmonary bypass in children weighing less than 10 kilograms.

BACKGROUND: Cardiopulmonary bypass induces a systemic inflammatory response. This study investigated, in a pediatric population, cytokine-induced responses and their potential modification by intraoperative steroid administration. METHODS: Markers of the acute-phase response were measured perioperatively in 24 children weighing less than 10 kg undergoing cardiac operations. Those having operations with cardiopulmonary bypass were randomized to receive either no steroid (group I, n = 8) or 10 mg/kg methylprednisolone in the pump prime (group II, n = 10); patients undergoing nonbypass procedures were controls (group III, n = 6). RESULTS: In all groups, plasma interleukin-6 level was elevated (p < 0.01) above baseline throughout the post-operative period, peaking earlier in group I. Levels of C-reactive protein peaked at 48 hours, and postoperative core temperature was raised in all groups. Levels of interleukin-6 from 2 to 6 hours and C-reactive protein at 24 hours postoperatively were greater (p < 0.05) in group I than in group II. Maximum interleukin-6 level, C-reactive protein level, and temperature were all significantly greater in group I than in group III. Maximum interleukin-6 level correlated with maximum C-reactive protein level in group I only (rs = 0.76; p < 0.05) and showed no association with temperature. Duration of bypass did not correlate with levels of interleukin-6. CONCLUSIONS: This study demonstrated a marked acute-phase response to operation; the greater response to procedures with cardiopulmonary bypass was abrogated by intraoperative steroid administration. The importance of interleukin-6 as an inducer of acute phase proteins after bypass is supported by its association with C-reactive protein levels, but other factors must be important in the induction of pyrexia.

Postinfarction ventricular free wall rupture: strategies for diagnosis and treatment.

Ventricular free wall rupture is a recognized complication of myocardial infarction. In recent years, the widespread availability of echocardiography has enabled prompt antemortem diagnosis. Consequently, an avenue for lifesaving surgical intervention has emerged for this hitherto fatal condition. We review the pathology and discuss strategies for diagnosis, resuscitation, and definitive surgical intervention. We illustrate this review using our experience with a patient whose condition was diagnosed by transthoracic echocardiography and who successfully underwent emergency operation.