Yukiyasu Sezai

Low-dose continuous infusion of human atrial natriuretic peptide during and after cardiac surgery

BACKGROUND We evaluated the effects of human atrial natriuretic peptide (hANP) during cardiopulmonary bypass (CPB). METHODS Forty patients undergoing coronary artery bypass grafting were investigated. A group of patients given hANP for 24 hours from the start of CPB (hANP group) was compared with a non-hANP group. Parameters examined were hemodynamics, urine volume, dosage of furosemide, respiratory index, pleural effusion, ANP, cyclic guanosine monophosphate, renin activity (renin), angiotensin-II, aldosterone, and glomerular filtration rate. RESULTS Central venous pressure, systemic vascular resistance index, and pulmonary vascular resistance index were significantly lower in the hANP group than in the non-hANP group. The hANP group showed significantly higher levels of ANP, cyclic guanosine monophosphate, glomerular filtration rate, and respiratory index, and significantly lower levels of renin, angiotensin-II, aldosterone, and pleural effusion, as compared with the non-hANP group. The dosage of furosemide was significantly lower and the urine volume was significantly larger in the hANP group. CONCLUSIONS hANP can satisfactorily compensate for the shortcomings of CPB by decreasing the peripheral vascular resistance, suppressing the renin-angiotensin-aldosterone system, and exerting a strong diuretic effect.

Optimal treatment of type B acute aortic dissection: long-term medical follow-up results.

BACKGROUND The aim of this study is to assess the long-term outcome of medical treatment and determine recent surgical indications for type B acute aortic dissection. METHODS In the last 8 years, 79 patients were admitted to our hospital with type B acute aortic dissection. We medically treated patients at the time of onset, regardless of the aortic diameter and blood patency status in the false lumen. If the maximum diameter of dissected aorta exceeded 60 mm in any stage, early or elective surgery was performed. The mean follow-up duration was 41.2 months. We evaluated operation free rate and actuarial survival rate. RESULTS Thirteen patients underwent early or elective operations of the descending aorta. At the time of onset, the maximum aortic diameter of these patients was significantly larger than that of medically managed patients (55.8 +/- 4.4 mm vs 44.6 +/- 8.2 mm; p = 0.0004). Two patients underwent emergency axillo-femoral bypass for leg ischemia. Of the other 64 patients, who were medically managed, 2 patients had type A dissection develop during follow-up, 3 died during the initial hospital stay (1 from rupture, 1 from bronchial asthma, and 1 from gut ischemia), and 1 died of pneumonia 6 months after onset. Operation free rate was 98.6% at 1 month, 90.0% at 1 year, 78.7% at 3 years, and 69.5% at 8 years. Actuarial survival rate of medically managed patients was 98.4% at 1 month and 93.5% at 8 years. CONCLUSIONS Medical treatment of type B acute aortic dissection produced good results. Surgical intervention for type B dissection should be done when the maximum aortic diameter exceeds 60 mm.

The Role of Pulsatility in End-Organ Microcirculation After Cardiogenic Shock

To estimate the effectiveness of pulsatility in end-organ microcirculation after cardiogenic shock, experimental studies using swine were done. Cardiogenic shock was produced in 14 pigs by ligating the left anterior descending branches so that mean aortic pressure dropped to 60% of the control value. After inducing shock, left atrial to ascending Ao bypass was initiated. A pneumatic pulsatile pump (Zeon Medical Inc, Tokyo, Japan) was used in seven pigs (Group P) and a centrifugal pump (BP-80, BioMedicus Inc, Minneapolis, MN) in seven (Group NP). In both groups, about half the usual cardiac output was supported for 3 hr, maintaining mean aortic pressure at approximately 100 mm Hg. The pulse pressure was 36.6 +/- 4.6 mm Hg in Group P, and 14.3 +/- 1.5 mm Hg in Group NP. Epicardial and endocardial regional flows recovered after assist in both groups. There were no significant differences between the two groups. However, liver tissue flow, renal cortex flow, and stomach mucous flow in Group P was significantly higher than those of Group NP after support (p < 0.05). In addition, arterial blood ketone ratio in Group P was 0.61 +/- 0.13 vs 0.39 +/- 0.06 in Group NP, a significant difference (p < 0.05). These results suggest that in uneven blood flow distribution of end organs after cardiogenic shock, pulsatility was effective in improving and maintaining function and microcirculation of end organs, preventing multiorgan failure.

Effect of pulsatile and nonpulsatile assist on heart and kidney microcirculation with cardiogenic shock.

To estimate microcirculation of the heart and kidney in pulsatile and nonpulsatile-assisted circulation, a comparison study was done using a swine model. Acute myocardial infarction was made by ligation of the left coronary artery branches. After cardiogenic shock, animals were divided into 3 groups as follows: Group C (n = 6), no assist provided; Group NP (n = 6), assisted by a nonpulsatile pump (Bio-Medicus BP-80); Group P (n = 6), supported by a pulsatile pump (Nippon Zeon). Left coronary artery flow, endocardial and epicardial regional flows, and renal cortex and medulla tissue blood flows were measured. Left coronary artery flow and endocardial and epicardial tissue blood flows decreased in cardiogenic shock, and they recovered to the control level soon after support in both Group N and Group P. Renal medulla and cortex tissue blood flows decreased in cardiogenic shock, and these flows did not recover in either Group N or P. However, cortex blood flow in Group P did improve, but it did not improve in Group N. These results suggested that pulsatile assist was more effective than nonpulsatile assist for microcirculation after cardiogenic shock to avoid deterioration of major organ functions.

Evaluation of valve sound and its effects on ATS prosthetic valves in patients’ quality of life

BACKGROUND We interviewed patients and carried out frequency analyses to compare the closing sounds of ATS and St. Jude Medical (SJM) prosthetic valves. METHODS Forty-five patients undergoing valve replacements using ATS valves were investigated. We interviewed patients at 1 month and 1 year after the operation, and carried out frequency analysis to investigate the prosthetic valves closing sound. RESULTS According to the results of the interviews, 84.4% of patients with ATS valves were not aware of the valve sounds. ATS valves scored significantly lower than SJM valves on audibility of the valve sound, disturbance during daytime, sleep disturbance, request for replacement with a soundless prosthetic valve, audibility to others, and noise index. According to the frequency analysis on the prosthetic valves closing sound, the sound peak of the ATS valves was around 1.2 kHz, and the sound pressure of the ATS valves was significantly lower than that of the SJM valves. CONCLUSIONS Though a further long-term observation on thromboembolism and hemolysis is needed for evaluation of prosthetic valves, the ATS valve is presently considered to impart a better quality of life.

Efficacy of continuous low-dose human atrial natriuretic peptide given from the beginning of cardiopulmonary bypass for thoracic aortic surgery.

PurposeCardiac surgery performed under cardiopulmonary bypass (CPB) causes abnormalities of the renin-angiotensin-aldosterone system, resulting in decreased urine output and an accumulation of water in the third space. We studied the efficacy of continuous low-dose human atrial natriuretic peptide (hANP) in patients undergoing thoracic aortic surgery.MethodsWe divided 40 patients undergoing thoracic aortic surgery into two groups: the hANP group, which received 0.02 μg/kg per minute of hANP and the non-hANP group, which did not. The hemodynamics, urine output, intensive care unit (ICU) and hospital stay, bleeding volume, homologous blood transfusion volume, furosemide dose, corrected KCl volume, and postoperative respiratory, hepatic, and renal function were compared in the two groups.ResultsThe urine output during CPB and from CPB weaning to return to ICU was significantly better in the hANP group. The bleeding volume, homologous blood transfusion volume, furosemide dose, and corrected KCl volume were all significantly less in the hANP group.ConclusionsThese findings support the consensus that hANP exerts its diuretic effects to their full potential when administered continuously at low doses during thoracic aortic surgery. We found it to be effective for postoperative hemostasis and for preventing ischemic reperfusion injury.

Heat and pain sensations induced by arterial injection of low-osmolality contrast media: a comparison of patients' discomfort with ionic saline, nonionic glucose, and vasodilator nitrate.

C linical symptoms such as heat and pain are two of the most frequent and finpleasant adverse effects experienced after intravascular injection of iodinated contrast media. Recently, nonionic dimeric contrast media (iotrolan, iiodixanol) have been developed [1], and their osmolality has been reduced to the physiologic level. However, subjective discomforts associated with these contrast media have not yet been eliminated. Although it has been established that heat and pain are caused mainly by tile high osmolality of the contrast media [2], it is possible that other factors also may play active roles. The aim of this study was to determine what factors and mechanisms are involved in causing heat and pain from the administration of the contrast media presently being used. The following agents were analyzed in our study: glucose as a model of a nonionic agent, saline (NaCl) as a model of an ionic agent, and nitrate as a vasodilator. Clinical studies on heat and pain induced by contrast media have been conducted [1, 3-7], but studies with test solutions involving actual patients have not been reported [8, 9]. Our study was designed to obtain the expression of sensations, which could be obtained only from human volunteers.

Experiences of Postcardiotomy Assist: Pneumatic Ventricular Assist Device or Venoarterial Bypass with Percutaneous Cardiopulmonary Support

From October 1982 to the present, 16 patients have been supported by a pneumatic ventricular assist device (VAD). Since April 1990, we have introduced a venoarterial bypass (VAB) with percutaneous cardiopulmonary support (PCPS) system. This PCPS system was used in 12 patients. The long-term survival rate of PCPS cases (41%) was much better than that of VAD cases (19%). The main cause of death in VAD cases was multiple organ failure (MOF). Although VAB was initiated more recently than VAD, the duration on support was longer in the VAD group than in the VAB group. Because of the longer support duration and the presence of many patients with MOF, coagulopathy deteriorated more readily in the VAD group than in the VAB group. In the case of postcardiotomy cardiopulmonary bypass weaning or low-output syndrome (LOS), the VAB with PCPS system should be applied first under intraaortic balloon pumping assist because of its simplicity and low cost. Thereafter, VAD should be applied in cases refractory to VAB support.

Coronary Microcirculation During Left Heart Bypass with a Centrifugal Pump

To estimate coronary microcirculation during left heart bypass (LHB), we performed an experimental comparison study of LHB and intraaortic balloon pumping (1ABP). LHB was performed with a BioMedicus BP-80 pump supporting half of the flow of cardiac output whereas the IABP was pumped in a 1:1 mode for cardiogenic shock in a swine model. Coronary circulations were analyzed by electromagnetic flowmeter, pulsed Doppler velocimeter, and laser Doppler flowmeter. Left ventricular end-diastolic pressure (LVEDP) was reduced significantly by LHB. Although there was no significant difference in epicardial flow between the LHB and IABP groups, endocardial flow was increased significantly by LHB. In the LHB group, the systolic reverse wave of the coronary velocity called a myocardial invalid circulation was reduced remarkably. There was a significant inverse correlation between endocardial flow and LVEDP. These results suggested that LHB was more effective for myocardial microcirculation than was IABP.

Comparative study of harvest-site complications following coronary artery bypass grafting between the radial artery and the saphenous vein in identical patients.

PurposeThe aim of this study was to assess the early outcome for complications associated with the radial artery harvest site, in comparison to using the saphenous vein, in patients harvested for both vessels.MethodsDuring the last 2 years, 134 radial arteries were used in 133 patients, and the saphenous vein was also concomitantly used in 94 patients. We assessed the post-harvest forearm perception using a questionnaire that contained two statements regarding pain and numbness in those 94 patients. The incidences of the harvest-site hematoma and infection were also compared between both the arms and legs where the grafts were harvested.ResultsNumbness of the harvest site was indicated in 26.6% (radial artery) and 33.0% (saphenous vein), respectively (P = 0.4252). Hematoma was found in 6.4% and 12.8%, respectively (P = 0.2152). On the other hand, the incidences of pain and wound infection were significantly lower in the radial artery sites (pain: 1.1% vs 23.4%, P = 0.0002; infection: 2.1% vs 11.7%, P = 0.0182).ConclusionsOur early experience suggests that the use of the radial artery is safe and also demonstrates a lower incidence of harvest-site complications than saphenous vein harvesting in patients where both vessels are used as harvest sites.