[Two cases of complete transection of the thoracic aorta caused by blunt chest trauma].

Two patients with complete transection of the thoracic aorta, caused by blunt chest trauma, were survived after successful surgical repair. Only seven such cases are reported in the Japanese literature. The present cases were 52- and 28-year-old males injured in different accidents by rapid deceleration, both at collision with the rear of a parked trunk. The first case, on the fifth day of hospitalization, suddenly went into shock with severe thoracodorsal pain. The second case developed hemothorax soon after the accident. Both cases were diagnosed with angiography. The lesions were located in the upper portion of the descending aorta. The operations, performed on the 13th and 34th days after the respective accidents, combined median sternotomy with left thoracotomy through the 3rd intercostal space. The first case suffered complete transection of the aorta at the ductal ligament. In the second case, the intima and media of the descending aorta, at 8 cm below the branching of the left subclavian artery, were affected by complete transection. We operated with a V-A bypass of which cannulation was performed to right atrium and left femoral artery in the first case, and with an ascending aorta-left femoral artery bypass with a centrifugal pump in the second case. The lesions were repaired with 26 mm and 20 mm woven Dacron grafts, respectively. The patients have recovered sufficiently to do normal daily lives. In cases with circumferential transection of the thoracic aorta caused by blunt chest trauma, only those with pseudoaneurysm formation, who remain in a hemostatic state can be saved by surgery, We conclude that if the hemodynamic state is stable and blood pressure is strictly controlled in such cases, the elective operation can be performed.

[A case report of emergency surgery for ruptured thoracic aortic aneurysm into the right thoracic cavity].

Rupture of aneurysm of descending thoracic aorta into the right thoracic cavity is an uncommon manifestation and, therefore, carries a high mortality rate. Sixty seven-year-old female was referred to our hospital due to ruptured aneurysm of descending thoracic aorta into the right thoracic cavity. Emergency operation was performed to replace the ruptured descending thoracic aorta through a left thoracotomy and to remove huge hematoma in the right thoracic cavity through a right thoracotomy. Post-operative chest radiograph showed well-expanded right lung which appears to prevent a serious respiratory complication. The patient recovered uneventfully after seven days of respiratory support.

Left ventricular function during exercise after aortic valve replacement.

To evaluate the difference in left ventricular function during exercise after successful aortic valve replacement, left ventricular function was investigated using radionuclide angiography in 12 patients with normal resting left ventricular systolic function. Patients were divided into two groups: Group 1 was comprised of 5 patients after aortic valve replacement for aortic stenosis and group 2 was comprised of 7 patients for aortic insufficiency. Left ventricular ejection fraction increased significantly during exercise in both groups. The increase in systolic arterial pressure to left ventricular end-systolic volume was significantly larger in group 1 than group 2, whereas the increase in left ventricular end-diastolic volume was significantly larger in group 2 than group 1. Thus, increase in left ventricular contractility played an important role in regulating increased left ventricular ejection fraction during exercise in patients with aortic prostheses for aortic stenosis, whereas increase in left ventricular end-diastolic volume played an important role in patients with aortic prostheses for aortic insufficiency.

Effect of cardioplegic preservation on intracellular calcium transients.

Intracellular Ca2+ ([Ca2+]i) plays a pivotal role in the regulation of cardiac function. We investigated the effect of cardioplegic preservation on [Ca2+]i transients in the isolated and perfused guinea pig heart loaded with a fluorescent Ca2+ indicator (fura-2). The measurements of [Ca2+]i transients and isovolumetric left ventricular pressure revealed that [Ca2+]i transients and mechanical responses to [Ca2+]i were markedly altered during 15 minutes of normothermic global ischemia and after reperfusion. First, [Ca2+]i transients remained during ischemia without generation of active force of contraction. Such a manifestation of depressed sensitivity of the myofilaments to Ca2+ persisted for the first 5 minutes after reperfusion. Second, the amplitude of [Ca2+]i was diminished during ischemia and reperfusion. Third, diastolic [Ca2+]i was increased during ischemia and especially at the onset of reperfusion. Bolus infusion of cold St. Thomas' Hospital solution abolished [Ca2+]i transients and left ventricular pressure development at an end-diastolic level. Moreover, improved recovery of left ventricular function during reperfusion afforded by the hypothermic cardioplegia was intimately related to its ability to modulate impaired [Ca2+]i transients and mechanical responses to [Ca2+]i; improvement of systolic left ventricular function appears to be produced by restoration of Ca2+ sensitivity of the myofilaments and the amplitude of [Ca2+]i transients, whereas better diastolic compliance of the left ventricle is ascribed to significantly lower diastolic [Ca2+]i. These results may provide new insight into the mechanism of cardioplegic preservation on the basis of [Ca2+]i transients.

Effects of amiloride and an analogue on ventricular arrhythmias, contracture and cellular injury during reperfusion in isolated and perfused guinea pig heart.

The present study was designed to examine whether activation of Na+/H+ exchange and subsequent massive Ca2+ influx via Na+/Ca2+ exchange are involved in the pathogenesis of myocardial reperfusion injury. We tested the effects of 1 mM amiloride, which is known to inhibit both Na+/H+ and Na+/Ca2+ exchange, and 3 microM 5-(N-ethyl-N-isopropyl) amiloride (EIPA), which is known to act as a specific inhibitor against Na+/H+ exchange, on the incidence of ventricular arrhythmias, isovolumic left ventricular function and creatine kinase (CK) release during reperfusion after 15 or 30 min of global ischemia in the isolated and perfused guinea pig heart. Treatment of a normally perfused heart with amiloride decreased heart rate significantly and tended to increase coronary flow and left ventricular developed pressure (LVDP), whereas treatment with EIPA decreased all of these 3 measurements significantly. Treatment with amiloride or EIPA for 15 min before ischemia, and during reperfusion after 15 min of ischemia, under electrical pacing at 240 rpm to eliminate a negative chronotropic effect abolished ventricular tachycardia (VT) and ventricular fibrillation (VF) during reperfusion associated with highly significant inhibition of increases in left ventricular end-diastolic pressure (LVEDP) and CK release. Amiloride or EIPA pretreatment also inhibited the incidence of VF and increases in LVEDP and CK release significantly during reperfusion after 30 min of ischemia. However, amiloride was more effective in preventing these events than EIPA. The treatment with amiloride or EIPA only during reperfusion after 15 or 30 min of ischemia also decreased the incidence of VF and inhibited the increases in LVEDP and CK release significantly, though less effectively than the pretreatment modality. These results suggest that EIPA prevents ventricular arrhythmias, contracture and myocardial cellular injury during reperfusion after 15 min of ischemia by inhibiting Na+/H+ exchange, while amiloride exerts more powerful protection against these events than EIPA during reperfusion after 30 min of ischemia by inhibiting both Na+/H+ and Na+/Ca2+ exchange.

[The experimental study on long-term cardiac preservation: the efficacy of low-flow continuous perfusion with fluorocarbon].

We compared the effect of simple immersion and continuous perfusion on long-term cardiac preservation, and evaluated the effectiveness of perfusion with oxygenated fluorocarbon solution. The isolated rabbit hearts were preserved for 24 hours at 4 degrees C using the following five preservation techniques: (1) simple immersion with Collins M solution (Group I), (2) perfusion with oxygenated Collins M solution at a flow rate of 10 ml/hr (Group II), (3) perfusion with the same solution as in Group II at a flow rate of 20 ml/hr (Group III), (4) perfusion with oxygenated Collins M solution containing 10% fluorocarbon at a flow rate of 10 ml/hr (Group IV), (5) perfusion with the same solution as in Group IV at a flow rate of 20 ml/hr (Group V). The hearts of Group I showed a significant decrease of myocardial ATP and an increase of myocardial lactate during preservation compared to the hearts of perfusion groups. Assessment of isovolumic left ventricular function following 24-hour preservation using a support animal showed a significant decrease of Max dp/dt and increase of end-diastolic pressure in the hearts of Group I. Perfusion with fluorocarbon (Group IV and V) significantly increased oxygen consumption compared to Group II and III in association with minimum accumulation of myocardial lactate, indicating that aerobic metabolism during preservation is better maintained in the fluorocarbon-perfused hearts. Moreover, CPK release and myocardial water gain during preservation were significantly less, and left ventricular function following preservation was significantly better in these hearts. Increasing the flow rate from 10 ml/hr to 20 ml/hr resulted in sustained increase in perfusion pressure (1.80 +/- 0.53 to 3.70 +/- 0.34 mmHg) and myocardial water content (79.2 +/- 0.4 to 87.2 +/- 0.3%) during preservation in the hearts of Group III, but it did not further improve left ventricular function despite significant enhancement of myocardial oxygen uptake in both Group III and V. These results suggest that hypothermic low-flow continuous perfusion with oxygenated Collins M solution is superior to simple immersion with the same solution for long-term cardiac preservation, and that the addition of fluorocarbon to the perfusate enhances the efficacy of such a perfusion.

[Pseudomonas cepacia endocarditis successfully treated by surgery].

The patient was a 3-year-old female with coarctation of the aorta complicated by ventricular septal defect and mitral regurgitation. She underwent surgery for coarctation of the aorta at 7 months of age. We performed direct closure using a pledget for ventricular septal defect and valvoplasty with annuloplasty for mitral regurgitation. Infective endocarditis due to pseudomonas cepacia developed 3 months after the surgery, and echocardiography revealed vegetation in the ventricular septum and anterior leaflet of the mitral valve. After treatment with antibiotics, the second open heart surgery involving removal of the pledget used in the previous operation, reclosure of the ventricular septal defect, and mitral valve replacement was performed. The patient is healthy without recurrence of infective endocarditis 2 years and 2 months after the surgery.

Reperfusion injury induced by augumented oxygen uptake in the initial reperfusion period. Possible efficacy of extreme hemodilution.

This study was designed to investigate the relationship between myocardial oxygen consumption and oxygen-induced myocardial injury. Dog hearts were exposed to 40 min normothermic ischemia and then reperfused for 10 min with three oxygenated perfusates containing different hemoglobin concentrations and with moderate hemodilution. The experimental groups consist of a moderate hemodilution group (Group M) receiving 8 g/dl of hemoglobin, an extreme hemodilution group (Group E) given 4 g/dl of hemoglobin, and a hemoglobin-free autologous plasma group (Group F). Hearts in the non-ischemic control group (Group C) were also perfused with moderate hemodilution throughout. In Group C, Group M and Group E, the O2 tension of perfusates was maintained at about 100 mmHg and in Group F, at over 300 mmHg. Oxygen extraction at 5 min after reperfusion in Group C was 14%, in Group M and Group E less than 10%, but in Group F 70%. Oxygen consumption in Group F was more than twice that in Group E and surpassed that in Group C. Group M also showed a significant increase in oxygen consumption compared with Group E at 5 min after reperfusion. Among the ischemic groups, Group E showed improvement of left ventricular function almost comparable to Group C accompanied by a rapid decrease in myocardial lactate, improved preservation of myocardial adenine nucleotides and prevention of myocardial lipid peroxidation. In contrast, Group F showed persistently higher values of lipid peroxides and lactate, the poorest recovery of adenine nucleotides, and impairment of left ventricular function.(ABSTRACT TRUNCATED AT 250 WORDS)

Myocardial protection during open-heart surgery: preservation of myocardial metabolism and ultrastructure by cold coronary perfusion.

Myocardial protection by means of selective, continuous coronary perfusion with cold oxygenated blood of low flow rate and of low perfusion pressure is an excellent procedure both clinically and experimentally. This method should be particularly useful in poor-risk patients, for whom a maximal preservation of the myocardium is imperative.