Shogo Yokose

Effects of intraoperative administration of atrial natriuretic peptide

BACKGROUND Biological activity of endogenous atrial natriuretic peptide (ANP) may decrease during cardiopulmonary bypass. To evaluate the effects of intraoperative administration of exogenous ANP in patients undergoing cardiopulmonary bypass, we conducted a prospective randomized study. METHODS Eighteen patients undergoing mitral valve surgery were randomized to receive either ANP treatment (ANP group; n = 9) or no ANP treatment (control group; n = 9). Atrial natriuretic peptide was given immediately after initiation of cardiopulmonary bypass for 6 hours (0.05 microg x kg(-1) x min(-1)). Plasma ANP, brain natriuretic peptide and cyclic guanosine monophosphate (cGMP) levels, hemodynamic variables and renal function were assessed perioperatively. RESULTS Administration of ANP increased plasma cyclic guanosine monophosphate levels, urine output and fractional sodium excretion, and decreased preload, afterload and plasma brain natriuretic peptide levels significantly (p < 0.05). Plasma cyclic guanosine monophosphate levels correlated with plasma ANP levels (r = 0.95, p = 0.0001), correlated with fractional sodium excretion (r = 0.53, p = 0.02), and correlated inversely with systemic vascular resistance (r = -0.54, p = 0.02). CONCLUSIONS Intraoperative administration of ANP had potent effects on natriuresis and systemic vasodilation by elevating cyclic guanosine monophosphate levels. The results suggest that the technique is useful for the management of hemodynamics and water-sodium retention after cardiopulmonary bypass.

Doppler Echocardiographic Evaluation of Prosthetic Valves in Tricuspid Position

Doppler echocardiographic characteristics of 29 normally functioning prosthetic valves (23 mechanical, 6 biological) and 8 obstructed mechanical prostheses in the tricuspid position are reported. In normally functioning prostheses, peak velocity, mean pressure gradient, and pressure-half time were 1.25 ± 0.18 m·sec−1, 2.6 ± 1.1 mm Hg, and 122.6 ± 30.7 msec, respectively. Although no significant differences were seen in peak velocity and mean pressure gradient between mechanical and biological valves, the pressure half-time was significantly greater in biological valves. All normally functioning prostheses had a mean pressure gradient ⩽5.5 mm Hg and pressure half-time < 200 msec. In obstructed bileaflet valves, peak velocity was 1.66 ± 0.28 m·sec−1, mean pressure gradient was 6.1 ± 2.8 mm Hg, and pressure half-time was 265.8 ± 171.7 msec. These Doppler data were significantly greater than those in normally functioning valves where the mean pressure gradient was ⩽5.1 mm Hg and the pressure half-time was ⩽156 msec in all except one patient. Pathological obstruction of a tricuspid prosthesis can be strongly suspected in patients with a mean pressure gradient > 5.5 mm Hg and a pressure half-time > 200 msec on Doppler echocardiography.

Effects of angiotensin-converting enzyme inhibitor during warm blood cardioplegia

BACKGROUND Effects of captopril, an angiotensin-converting enzyme inhibitor, during warm blood cardioplegia were assessed in the blood-perfused, isolated rat heart. METHODS The isolated hearts were arrested for 60 minutes with warm blood cardioplegia given at 20-minute intervals and were reperfused for 60 minutes. The control group (n = 10) received standard cardioplegia and the captopril group (n = 10) received cardioplegia supplemented with captopril (2 mmol/L). Cardiac function, myocardial metabolism, and cardiac release of circulating adhesion molecules were assessed before and after cardioplegic arrest. RESULTS Left ventricular end-diastolic pressure and -dp/dt were significantly (p<0.05) lower and coronary blood flow was significantly (p<0.05) greater in the captopril group than the control group during reperfusion. The captopril group resulted in significantly (p<0.05) less cardiac release of lactate, thiobarbituric acid reactive substances during reperfusion. Cardiac release of intercellular adhesion molecule-1 was significantly (p<0.05) less in the captopril group at 60 minutes of reperfusion. CONCLUSIONS The results suggest that supplementation of captopril during warm blood cardioplegia provides superior myocardial protection by suppressing lipid peroxidation and leukocyte-endothelial cell interaction during reperfusion.

Successful repair of mesenteric ischemia in acute type A aortic dissection

A 64-year-old man with acute type A aortic dissection had superior mesenteric artery occlusion and marked metabolic acidosis. By an emergency laparotomy, bypass grafting from the left external iliac artery to the superior mesenteric artery was performed with great saphenous vein. After deep sedation and antihypertensive management in the intensive care unit, the acidosis resolved, and central repair was carried out. At 10 months postoperatively, his course has been uneventful without mesenteric complications.

Surgical treatment for graft stenosis after repair of an interrupted aortic arch: Report of two cases

We report herein two cases of patients who underwent successful reoperation for graft stenosis after repair of an interrupted aortic arch (IAA). The first patient was a 10-year-old girl who suffered from upper limb hypertension 9 years after her initial operation. Cardiac catheterization revealed a pressure gradient of 55mmHg across the repaired arch. At reoperation, a left subclavian turndown anastomosis was performed, following which the hypertension resolved and a cardiac catheterization done 5 years later demonstrated sufficient growth of the restored arch with no significant gradient. The second patient was a 17-year-old boy who suffered from general fatigue and intermittent hypertension 12 years after his initial operation. Cardiac catheterization revealed a gradient of 60mmHg across the repaired arch. He underwent an extraanatomic ascending to descending aortic bypass employing an additional 18-mm graft, and a postoperative cardiac catheterization showed no gradient between the ascending and descending aorta. Our experience has shown that IAA should be repaired without prosthetic grafts if possible. Although extraanatomic bypass is useful for reducing the operative risks at reoperation, a large graft should be used to avoid the need for a third operation. For young children expected to outgrow a second graft, performing an endogenous anastomosis, such as a left subclavian turndown anastomosis, should be considered as an alternative.

A SAM valve prosthesis in the mitral position: report of a case of long-term survival

No long-term survivals over 20 years after valve replacement with SAM (Sakakibara-Arai-Mera) valve prostheses have been described. We report a 57-year-old woman who survived for 31 years after mitral valve replacement with the SAM valve (Type M, 5M). Echocardiography revealed remarkable dilatation of the left atrium and moderate tricuspid regurgitation. Cineradiography, however, showed no restricted or asymmetric disc movement of the SAM valve. Cardiac catheterization revealed moderate pulmonary hypertension (64/30mmHg), with a mean pulmonary capillary wedge pressure of 25mmHg and a mean transprosthetic pressure gradient of 13mmHg. The mitral valve area was calculated to be 0.9 cm2. No findings of pannus overgrowth around the SAM valve were confirmed on echocardiograms or left ventriculograms. Although the diagnosis of prosthetic valve obstruction resulting from pannus formation was suspected, the patient strongly refused replacement of the SAM valve because of her poor prognosis with bilateral breast cancer with systemic metastases. We believe that this patient may be the last living patient with the SAM valve.