Protection of the ischemic myocardium during percutaneous transluminal coronary angioplasty

Therapeutic balloon coronary angioplasty provides a useful model for studying the effects of epicardial coronary artery occlusion in conscious humans. In addition, it is a potent model in which the effectiveness of interventions designed to ameliorate ischemia can be evaluated. Whereas intravenous beta-adrenergic blocking drugs and nitrates appear to have a limited protective effect, the regional (i.e., intracoronary) use of beta-adrenergic blocking drugs and calcium antagonists seem more potent. Currently, coronary venous retroperfusion with arterial blood does not appear practical, and the intraaortic balloon is a useful adjunctive measure in relatively few patients undergoing percutaneous transluminal coronary angioplasty. In contrast, the direct anterograde delivery of oxygen-rich blood or fluorocarbons holds promise as a reliable means of providing local myocardial protection. If ischemia could be markedly reduced, percutaneous transluminal coronary angioplasty might be applied safely in more high-risk clinical settings. In addition, if prolonged balloon inflation could be performed, there might be an increase in primary success rate and possibly a reduction in restenosis rate.     

Protection of ischemic myocardium by whole-body hypothermia after coronary artery occlusion in dogs

Anesthetized dogs were cooled to a core body temperature of 26°C. or maintained at a body temperature of 37°C. during periods of 5 and 10 hours of LAD coronary artery occlusion. Subsequent macroscopic dehydrogenase enzyme mapping showed that ischemic injury was 25 per cent less after 5 hours of coronary occlusion and 20 per cent less after 10 hours of occlusion in hypothermic dogs than in normothermic controls. The heart rate and left ventricular minute work in hypothermic dogs decreased to roughly half the levels measured in normothermic animals, while left ventricular contractility was 10 to 40 per cent lower in hypothermic dogs than in normothermic dogs. However, cardiac index and left ventricular end-diastolic pressure were unchanged by whole-body cooling. Thus, hypothermia appeared to diminish the oxygen requirements of the ischemic myocardium without reducing the performance of the heart as a pump. Hypothermia may be useful as a therapeutic adjunct to myocardial revascularization or pharmacologic interventions.     

Substernal goiters. 218 operated cases]

The authors are presenting a retrospective study on 218 retrosternal goiters operated between 1968 and 1991. 33% of the goiters were incidentally discovered on a plain X-ray of the chest. Symptoms of compression were present in 50.5% of patients and hyperthyroidism in 16.5%. Respiratory manifestations were more frequent and more severe in patients aged 70 and more. Moreover 90% of those old patients were symptomatic. Goiters migrated anteriorly in 57.7% of cases, posteriorly in 33.9%, both anteriorly and posteriorly in 5.5%. Type of migration was unknown in 2.5%. 3.7% were malignant. 27 patients with respiratory symptoms received corticosteroids to reduce the airway compression. Among 52 patients with hyperthyroidism, 36 were given antithyroid drugs. Among them, some received corticosteroid drugs in order to reduce risks of mediastinal compression. A simple cervicotomy was adequate in 92.7% of case and was completed by sternotomy in 7.3%. The operation was iterative for relapsing or forgotten thoracic goiters in 24 cases. Morbidity was slight even for sternotomized patients. Mortality was noted in 2 cases (0.9%) one of them operated on for poorly-differentiated and suffocating carcinoma of the thyroid. We advise a straightforward surgical attitude as a result of the slight morbidity and mortality, even in sternotomized patients in order to avoid severe compressive complications of the airways.     

Protection of the ischemic dog myocardium with carnitine

In 25 open chest anestheslzed dogs, left anterior descending coronary arterial blood flow was measured with an electromagnetic flowmeter while aortic blood pressure and epicardlal electrocardiograms were recorded. Ischemia was produced in the left anterior descending arterial bed by decreasing mean flow to one third of control levels for a 5 minute period with a micrometer snare device. This produced an increase in S-T segment deviation greater than 4 mv in the ischemic bed. Control and ischemic left anterior descending arterial bed tissue samples were obtained by drill biopsy and were analyzed for adenosine triphosphate (ATP) and creatine phosphate levels and adenlne nucleotide translocase activity. The ATP levels decreased from 5.6 ± 1.2 to 3.6 ± 1.4 μmoles/g, and creatine phosphate decreased from 15.3 ± 4.6 to 5.8 ± 3.8 μmoles/liter. The adenine nucleotide translocase activity decreased from an average control value of 42,957 ± 9,480 to 29,100 ± 6,609 disintegrations per minute (dpm)/mg during the 5 minute period of ischemia. With the ischemia maintained, 100 mg/cc of L-carnitine was infused into the ischemic left anterior descending arterial bed at a rate of 1 cc/min for 5 minutes (17 dogs), and 80 mg/kg of D-L carnltine was given intravenously in 8 dogs. The epicardial S-T segment deviation decreased to approximately 2 mv after the carnltine infusion, with ischemia maintained. A third biopsy sample of the ischemic bed showed that the ATP level had increased to 5.2 ± 1.1 and the creatine phosphate to 10.8 ± 4.8 moles/g; the adenine nucleotide translocase activity had increased to 37,800 ± 7,210 dpm/mg. In 9 dogs ventricular fibrillation developed at this level of ischemia before infusion of carnitine, whereas only one dog had fibrillation at comparable levels of ischemia after infusion.

These results support the hypothesis that infusion of carnitine may benefit the ischemic myocardium by maintaining tissue levels of free carnitine, reversing inhibition of adenine nucleotide translocase by long chain acyl coenzyme A esters and in this manner restoring mitochondrial function.     

Immediate and long-term results of surgery of the tricuspid valve. APropos of 62 operated cases]

Operative and late results in a series of patients operated on the tricuspid valve (replacement or annuloplasty) at the moment of surgery upon mitral and aortic valves are reported. Functional tricuspid insufficiency carries a greater risk than organic tricuspid disease. Considering the duration of the underlying mitral disease, four grades are set up for the mitro-tricuspid patient allowing for prognosis and indication of the type of surgery to be done on the tricuspid valve.     

Stenosis of the common trunk of the left coronary artery. Personal experience with 17 patients]

The Authors have presented the clinical, hemodynamic, coronary arteriographic and left ventriculographic findings, and the results of medical and surgical treatment in 17 patients with main left coronary artery disease (MLCA). Clinically MLCA disease can only be suspected, in the AA's experience, if a patient presents with markedly positive exercise stress test and/or unstable angina. Coronary arteriography and left ventriculography confirmed the high incidence of associated 2-3 vessel coronary artery disease and of severe left ventricular segmental wall motion abnormalities. Surgical results and clinical follow up have indicated a better prognosis and quality of life in operated, compared with medically treated patients. Our experience confirms that MLCA disease is a dangerous clinical entity, which, when suspected, must be managed with proper indication to coronary arteriography and aorto-coronary bypass surgery, both associated, in our experience, with acceptable morbidity and mortality and good long term results.     

Effects of perhexiline maleate on coronary flow distribution in the ischemic canine myocardium.

Intravenous perhexiline maleate in a canine preparation with fixed coronary flow increases coronary diastolic pressure. It also redistributes coronary flow so as to preserve endocardial flow. Myocardial oxygen consumption was reduced and lactate uptake enhanced by the drug. It had no effect upon the threshold for ischemic-induced left ventricular failure.     

Immediate results of percutaneous mitral valvuloplasty using Inoue catheter. Personal experience in the first 15 cases]

Mitral valvuloplasty with an Inoue balloon catheter was performed at our institution in 15 patients affected by mitral stenosis. All were severely symptomatic (class NYHA III or IV). Transthoracic and transesophageal echocardiography showed a mitral score less than 10 (Wilkins criteria). Patients with thrombi in the left atrium and those with important mitral regurgitation were excluded. The mitral valve area increased from 0.98 +/- 0.2 to 1.89 +/- 0.4 cm2 and the transvalvular gradient decreased from 18.2 +/- 7.5 to 6.7 +/- 3.7 mmHg. There was a small increase of the mitral regurgitation. Two complications occurred during the procedure: the first was a haemopericardium, which was percutaneously drained, and the other a rupture of the anterior mitral leaflet with acute, severe mitral regurgitation necessitating urgent surgical correction. Applying the criteria of Herrmann, the results were optimal in 11 and suboptimal in 3 cases.     

Oxygen utilization and coronary vascular reserve in the ischemic myocardium following acute coronary occlusion in the dog.

Oxygen extraction ratio (OER), oxygen consumption, heat production index, and flow (measured both as venous outflow and heat clearance) were measured in an area of myocardium to be rendered ischemic by acute occlusion of the anterior descending coronary artery. Prior to occlusion a linear relation was established between heat clearance and venous outflow. Heat production index and OER also showed a relationship, but its precise mathematical nature is not yet clear. Acute artery occlusion produced a rise in OER (from 58.4 to 84.4%) and a fall in both venous outflow (30.7%) and heat clearance (35.4%); heat production index fell over 1 hr by 57.3% and thereafter remained unchanged. Oxygen consumption changes were variable but mainly showed a reduction. In the unstressed anaesthetized dog, OER was not maximal but with acute ligation rose markedly, in isolated instances to 100%. It is suggested that increase in OER might be an important component of coronary vascular reserve, that it might in part, at least, be mediated by diversion of blood from relatively non-nutritional channels to channels in which, especially under conditions of cardiac stress, extraction of oxygen can be maximum.     

Tissue and coronary venous pH in ischemic canine myocardium

Summary: The relationship between changes in myo-cardial tissue pH and local coronary venous pH during and after transient occlusion of the left anterior descending artery was investigated in 6 open chested an-esthesized dogs. Tissue pH was recorded with a needle pH electrode, and coronary venous pH with a specially designed catheter tip pH electrode. Myocardial tissue pH fell steadily after coronary occlusion, and had fallen by 0.107±0.043 pH units (mean±SD, n=12 occlusions) after 150 s. On reperfusion there was a further small fall in tissue pH to 0.138±0.035 units before tissue pH returned to control. In contrast, the fall of coronary venous pH during ischemia was small (0.15±0.027 after 150 s, n=12 occlusions). Within 5 s of reperfusion, a large fall in venous pH occurred, reaching a maximum of 0.150±0.072 at 20–30 s after reperfusion. During ischemia changes in tissue pH are poorly represented by changes in coronary venous pH. The size of the early change of venous pH during the reperfusion washout of retained metabolites is a better estimate of the fall of tissue pH. Measurement of metabolites in the coronary sinus of man during the washout after the end of an ischemic intervention such as atrial pacing is superior to measurements performed during pacing in providing biochemical evidence of myocardial ischemia.     

Aorto-coronary by-pass. Personal experience based on 342 cases operated on between April 1971 and December 1974 (author's transl)]

The authors report on the casuistry of aorto-coronary by-pass operations they performed between April 1971 and December 1974, discussing the criteria which indicate the necessity of operating, the principles of the operative techniques, and the results obtained. Out of a total of 342 operated cases, there was an operative mortality (within 30 days) of 3% in isolated by-pass cases, and 4% if one includes associated operations. In 3,5% of patients, postoperative necrosis was present. Almost the same values were found in the smaller group (66 cases) which underwent urgent by-pass operations. The authors consider that the aorto-coronary by-pass operation is a very useful treatment, both for stable and unstable angina, as long as the anatomo-functional conditions exist.