Masahiro Saigusa

OPTIMAL HEART RATE IN CARDIAC PACING IN CORONARY SCLEROSIS AND NON-SCLEROSIS

The main objects of cardiac pacing are to secure the best hemodynamic condition of the patient and to provide the greatest possible comfort. During longterm pacing of patients with atrioventricular block, we have learned that the greatest comfort is provided by adjusting the pacing rate to an arbitrary frequency which is termed the “optimal rate” and which varies from patient to patient. Our interest centered around the atrial rate because it was thought that hemodynamic conditions reflected upon the atrial rate. On the basis of clinical observations, hemodynamic studies, and subjective complaints from patients, we concluded that the optimal rate in ventricular pacing is obtained by making the atrial rate minimal. A comparison was made of the optimal rates thus set for patients with coronary sclerosis and non-sclerosis. Usually, the optimal pacing rate was determined as a range. This is explained by the theoretical analysis of our “circulatory function curve.”

Relationship of Plasma Aldosterone Concentration to Electrolytes and Acid-base Balance in Blood after Open Cardiac Surgery

Plasma aldosterone concentration was measured in 11 cardiac patients after open cardiac surgery, by the radioimmunoassay method, and the relationship of it to electrolytes and acid-base balance of blood was analyzed. Plasma aldosterone concentration was markedly elevated in patients with low cardiac output, who required postoperative drip infusion of Isoproterenol, and in addition, both remarkable metabolic alkalosis and increase of potassium excretion in urine were confirmed in these patients. Plasma aldosterone concentration correlated significantly with potassium excretion in urine and was inversely related with potassium balance. However, plasma potassium concentration or arterial pH had no correlation to it. Approximately an inverse correlation was found between the logarithm of the sodium/potassium ratio in urine and plasma aldosterone concentration. These data indicate that aldosterone is an important factor which produces potassium depletion after open cardiac surgery.

Transseptal left-heart catheterization with Swan-Ganz flow-directed catheter

Four cases of transseptal left-heart catheterization with the use of a Swan-Ganz flow-directed balloon-tipped catheter are reported. An 8.5F Teflon catheter covered with a Teflon tube (4 mm outer diameter) was inserted into the left atrium by the Brockenbrough technique. A Swan-Ganz catheter was then introduced into the left atrium through the Teflon tube and left-heart catheterization was performed. Unlike conventional methods, this method made it easier to insert a catheter into the left ventricle and also enabled advancement of the catheter into the aorta. Our experience suggests that this method is a valuable addition to cardiac catheterization laboratories.

Aortic homograft valve functioning for twenty-eight years in the tricuspid position

years in the tricuspid position To the Editor: The case history of a patient with a Hancock porcine heterograft valve (Medtronic, Inc, Minneapolis, Minn) implanted 22 years ago was reported by Wisheart.1 In 1971, we2 reported the replacement of a tricuspid valve with a preserved aortic valve homograft for Ebstein’s malformation. After 28 years, the patient is still alive and active with the homograft. A 12 year-old girl was admitted to our hospital for mild exertional dyspnea and polycythemia. On June 18, 1970, she underwent tricuspid valve replacement with an aortic homograft and suture closure of the atrial septal defect. The homograft was preserved in 70% alcohol for 7 weeks and was fixed to a Shumway-Angell ring (No. 26) by 2-layer continuous sutures. The reinforced valve was anchored to the “true anulus” of the tricuspid valve with interrupted sutures so as to leave the coronary sinus above it. No diastolic pressure gradient was detected between the right atrium and the ventricle. She was discharged from the hospital with sinus rhythm and has enjoyed an active life. The woman is now 41 years old and visited the outpatient clinic for a follow-up study after 28 years. Physical examination revealed no cyanosis and only a Levine grade 2/6 diastolic murmur over the precordium. An electrocardiogram showed complete atrioventricular block with a ventricular rate of 60 beats/min. Her condition was New York Heart Association class II. Echocardiographic study revealed a well-functioning homograft without evidence of calcification (Fig 1). A diastolic pressure gradient between the right atrium and the ventricle was estimated as 5 mm Hg. A color Doppler study showed moderate tricuspid regurgitation. Stark and associates3 reported that the longest surviving homograft conduit was 22.7 years in his series of patients with subpulmonary homograft conduits. Recently, Rizzoli and coauthors4 reported long-term results of prosthetic valve replacement in the tricuspid position, and the longest survival time was 27.8 years after insertion of a mechanical valve. However, the very long-term result of homografts in the right side of the heart is still unknown. Between 1967 and 1969, 5 patients survived the operation in our hospital with homografts in the aortic or tricuspid position. All 4 homografts in the aortic position were replaced within 9 years, 3 because of valve malfunction and 1 because of infectious endocarditis. On the other hand, the valve in the tricuspid position is still functioning, probably because of the low mechanical stress to the valve leaflets in the right side of the heart. In conclusion, the experience with our patient for more than a quarter of a century suggests the feasibility of homograft use in the tricuspid position, even in adolescents. Motohiro Kawauchi, MD Masahiro Saigusa, MD Akira Furuse, MDa Shinichi Takamoto, MD Department of Cardiothoracic Surgery Faculty of Medicine University of Tokyo 7-3-1, Hongo, Bunkyo-ku Tokyo, 113-8655, Japan JR Tokyo General Hospitala 2-1-3, Yoyogi, Shibuya-ku Tokyo, 151-8528, Japan 384 Letters to the Editor The Journal of Thoracic and Cardiovascular Surgery August 1999