[Tricuspid annuloplasty].

Isolated tricuspid valve disease is rare. In approximately 75% of the cases, the tricuspid regurgitation (TR) is caused by dilatation of right ventricle, tricuspid annulus, and pulmonary hypertension. The presence of TR associated with left-sided valve disease, especially mitral, is very common. According to ACC/AHA 2006 Guidelines for the management of patients with valvular heart disease, severe TR should be treated during operations for multivalvular disease (class I, level of evidence : C). Tricuspid annuloplasty is indicated even for mild TR in patients undergoing mitral valve surgery when there is pulmonary hypertension or tricuspid annular dilatation (class IIa, level of evidence : C). Techniques to deal with a dilated tricuspid valve annulus with normal leaflets and chordal structures include placation of the posterior leaflet annulus (bicuspidization), semicircular purse-string reduction of the anterior and posterior leaflet annuli (DeVega technique), and rigid or flexible rings or bands placed to reduce the annular size and achieve leaflet coaptation. The procedure is easy and safe. However, further studies are mandatory in cases of mild functuional TR to achieve better long-term outcome in patients with mitral valve disease undergoing mitral valve surgery.

Which factors predict the recovery of natural heart function after insertion of a left ventricular assist system?

BACKGROUND: Recent reports have demonstrated that use of a left ventricular assist system (LVAS) can initiate recovery of cardiac function, and subsequent weaning from the LVAS has attracted considerable interest. In this study we investigated reliable predictors of LVAS weaning. METHODS: Eighty-two patients underwent LVAS implantation between April 1994 and July 2006 at our institution. Cardiac function was restored in 8 patients, who were weaned from LVAS after a mean of 5 months (Group R). Thirty-three patients remained on LVAS support for >1 year (Group N) because natural heart function did not show adequate improvement. We retrospectively evaluated the differences between these two groups. Group R was younger, and had a shorter duration of heart failure than Group N (23.4 vs 36.7 years and 13.3 vs 56.1 months, p < 0.01, respectively). Pathologic findings showed that the interstitial fibrosis score was lower in Group R (p < 0.01). Three months after LVAS insertion, B-type natriuretic peptide (BNP) and fractional shortening (FS) were more favorable (66.6 +/- 46 vs 264.5 +/- 170 pg/ml, p < 0.01, and 23 +/- 17.1 vs 12 +/- 9.1%, p < 0.05, respectively) in Group R. Furthermore, Group R received a higher dose of beta-blocker (15.4 +/- 8.4 vs 5.8 +/- 3.9 mg, p < 0.05). CONCLUSIONS: Younger age, shorter history of heart failure, and less interstitial fibrosis were effective predictors of weaning from LVAS. Restoration of natural heart function was more rapid and more persistent in candidates for LVAS explantation, and presence of beta-blocker played a prominent role in improving cardiac function after LVAS implantation.

Redo aortic valve replacement with ''porcelain'' aorta in an aortitis patient. A case report.

We report a successful reoperation of aortic valve replacement with the severely calcified, ''porcelain'' aorta due to Takayasu's disease. The patient was a 46-year-old female diagnosed with aortic prosthetic valve failure. Takayasu's aortitis had been noted at 17 years old and the patient underwent aortic valve replacement for aortic regurgitation at age 32. Chest CT scan revealed severe circumferential calcification of the whole thoracic aorta. Echocardiography revealed 100 mmHg of pressure gradient across the aortic prosthetic valve with pannus formation. Replacement of the aortic prosthetic valve was performed using the selective cerebral perfusion method under deep hypothermia. The postoperative course was uneventful without any neurological disorder. Selective cerebral perfusion was a useful method to avoid cross clamping in severely calcified ascending aortic.

The role of diastolic pump flow in centrifugal blood pump hemodynamics.

We tried to verify the hypothesis that increases in pump flow during diastole are matched by decreases in left ventricular (LV) output during systole. A calf (80 kg) was implanted with an implantable centrifugal blood pump (EVAHEART, SunMedical Technology Research Corp., Nagano, Japan) with left ventricle to aorta (LV-Ao) bypass, and parameters were recorded at different pump speeds under general anesthesia. Pump inflow and outflow pressure, arterial pressure, systemic and pulmonary blood flow, and electrocardiogram (ECG) were recorded on the computer every 5 ms. All parameters were separated into systolic and diastolic components and analyzed. The pulmonary flow was the same as the systemic flow during the study (p > 0.1). Systemic flow consisted of pump flow and LV output through the aortic valve. The ratio of systolic pump flow to pulmonary flow (51.3%) did not change significantly at variable pump speeds (p > 0.1). The other portions of the systemic flow were shared by the left ventricular output and the pump flow during diastole. When pump flow increased during diastole, there was a corresponding decrease in the LV output (Y = -1.068X + 51.462; R(insert)(2) = 0.9501). These show that pump diastolic flow may regulate expansion of the left ventricle in diastole.

Prospective comparative study of brain protection in total aortic arch replacement: deep hypothermic circulatory arrest with retrograde cerebral perfusion or selective antegrade cerebral perfusion.

BACKGROUND: The purpose of this study was to compare the results of total aortic arch replacement using two different methods of brain protection, particularly with respect to neurologic outcome. METHODS: From June 1997, 60 consecutive patients who underwent total arch replacement through a midsternotomy were alternately allocated to one of two methods of brain protection: deep hypothermic circulatory arrest with retrograde cerebral perfusion (RCP: 30 patients) or with selective antegrade cerebral perfusion (SCP: 30 patients). Preoperative and postoperative (3 weeks) brain CT scan, neurological examination, and cognitive function tests were performed. Serum 100b protein was assayed before and after the cardiopulmonary bypass, as well as 24 hours and 48 hours after the operation. RESULTS: Hospital mortality occurred in 2 patients in the RCP group (6.6%) and 2 in the SCP group (6.6%). New strokes occurred in 1 (3.3%) of the RCP group and in 2 (6.6%) of the SCP group (p = 0.6). The incidence of transient brain dysfunction was significantly higher in the RCP group than in the SCP group (10, 33.3% vs 4, 13.3%, p = 0.05). Except in patients with strokes, S-100b values showed no significant differences in the two groups (RCP: SCP, prebypass 0.01+/-0.04: 0.05+/-0.16, postbypass 2.17+/-0.94: 1.97+/-1.00, 24 hours 0.61+/-0.36: 0.60+/-0.37, 48 hours 0.36+/-0.45: 0.46+/-0.40 microg/L, p = 0.7). There were no intergroup differences in the scores of memory decline (RCP 0.74+/-0.99; SCP 0.55+/-1.19, p = 0.6), orientation (RCP 1.11+/-1.29; SCP 0.50+/-0.76, p = 0.08), or intellectual function (RCP 1.21+/-1.27; SCP 1.05+/-1.15, p = 0.7). CONCLUSIONS: Both methods of brain protection for patients undergoing total arch replacement resulted in acceptable levels of mortality and morbidity. However, the prevalence of transient brain dysfunction was significantly higher in patients with the RCP.

[Aortoesophageal fistula due to ruptured thoracic aortic aneurysm: case report of successful primary reconstruction of esophagus].

We report a successful surgical case of 78-year-old woman with aortoesophageal fistula subsequent to the operation for sealed rupture of thoracic aortic aneurysm. She underwent one-stage operation consisted of esophagectomy, transmediastinal interposition of the stomach and esophagogastroanastomosis, to re-establish the gastrointestinal tract. The patient recovered well postoperatively without infection.

Relationship of blood pressure and pump flow in an implantable centrifugal blood pump during hypertension.

The purpose of this study was to evaluate the real time relationship between pump flow and pump differential pressure (D-P) during experimentally induced hypertension (HT). Two calves (80 and 68 kg) were implanted with the EVA-HEART centrifugal blood pump (SunMedical Technology Research Corp., Nagano, Japan) under general anesthesia. Blood pressure (BP) in diastole was increased to 100 mm Hg by norepinephrine to simulate HT. Pump flow, D-P, ECG, and BP were measured at pump speeds of 1,800, 2,100, and 2,300 rpm. All data were separated into systole and diastole, and pump flow during HT was compared with normotensive (NT) conditions at respective pump speeds. Diastolic BP was increased to 99.3+/-4.1 mm Hg from 66.5+/-4.4 mm Hg (p<0.01). D-P in systole was under 40 mm Hg (range of change was 10 to 40 mm Hg) even during HT. During NT, the average systolic pump flow volume was 60% of the total pump flow. However, during HT, the average systolic pump flow was 100% of total pump flow volume, although the pump flow volume in systole during HT decreased (33.1+/-5.7 vs. 25.9+/-4.0 ml/systole, p<0.01). In diastole, the average flow volume through the pump was 19.6+/-6.9 ml/diastole during NT and -2.2+/-11.1 ml/diastole during HT (p<0.01). The change in pump flow volume due to HT, in diastole, was greater than the change in pump flow in systole at each pump speed (p<0.001). This study suggests that the decrease of mean pump flow during HT is mainly due to the decrease of the diastolic pump flow and, to a much lesser degree, systolic pump flow.

Continuously maintaining positive flow avoids endocardial suction of a rotary blood pump with left ventricular bypass.

This study showed the usefulness of maintaining positive pump flow to avoid endocardial suction and as an assist bypass. Three calves were implanted with centrifugal pumps. Hemodynamics and pump parameters were measured at varying pump speeds (from 1,100 to 2,300 rpm). In each test pump, speed was adjusted to create 3 hemodynamic states: both positive and negative flow (PNF), positive and zero flow (PZF), and continuously positive flow (CPF). The pump flow volume was determined during systole (Vs) and diastole (Vd). Vs in PNF was 29.6 ml and was not significantly different from Vs in PZF (p > 0.15). Vd in PNF was significantly different from Vd in PZF (p < 0.05). All bypass rates of PNF were over 30% of pulmonary flow. All PZF bypass rates were between the PNF rate and the CPF rate. These data showed that PZF satisfied the minimum requirement of assist flow and was under 100% bypass. Thus, PZF may avoid endocardial suction.

Surgery in three-channeled aortic dissection. A 31-patient review.

OBJECTIVE: Three-channeled aortic dissection with 2 adjacent false lumens present is rare. METHODS: The 31 patients whose dissections we treated surgically accounted for 7.3% of the 426 patients with aortic dissection treated surgically between 1978 and May 1999. The 17 men and 14 women ranged in age from 24 to 77 years (mean: 45 +/- 12 years). Marfan syndrome was present in 18. Pain was observed at different times in 20. computed tomography scanning and magnetic resonance image proved useful in preoperative diagnosis. The morphology of the 1st and 2nd false lumens was Stanford type A + B in 13, type B + B in 15, type A + A in 2, and localized abdominal dissection in 1. RESULTS: Descending aortic replacement was done in 18 patients, thoracoabdominal aortic replacement in 7, ascending aortic replacement in 3, and others in 3. Five patients died in hospital and later during follow-up for 1-181 months (mean, 57 +/- 55 months). CONCLUSIONS: Pain recurring in patients with aortic dissection should alert the physician to the possibility of 3-channeled dissection and the necessity of surgery. The incidence of such dissection is high in patients with Marfan syndrome.

Valved conduit operation for aortic regurgitation associated with Behçet's disease.

OBJECTIVES: Aortic regurgitation associated with Behçet's disease is rare, and prosthetic valve detachment after aortic valve replacement is one of the most serious complications reported. We have investigated the surgical results of valved conduit operation in 8 patients. METHODS: Between 1987 and April 1999, 8 patients underwent surgery. There were 7 males and 1 female, and their ages ranged from 33 to 60 years (mean, 48 +/- 10 years). The valved conduit procedure was a modified Bentall operation. RESULTS: One patient died of arrhythmia during the hospital stay. The follow-up period in the other 7 patients ranged from 1 to 138 months after surgery (mean, 74 months). None of these 7 patients died during the follow-up period. Valve detachment needing redo-operation occurred in 1 patient, and he underwent a valved conduit operation again. CONCLUSIONS: Valved conduit reconstruction is indicated in patients with aortic regurgitation caused by Behçet's disease, in whom prevention of valve detachment is difficult even by current valve fixation methods.

Transmural necrosis of the esophagus secondary to acute aortic dissection.

A case of transmural ischemic necrosis of the esophagus secondary to aortic dissection is presented. A 66-year-old woman with acute type A aortic dissection underwent total arch replacement with a technique of deep hypothermic arrest and retrograde cerebral perfusion. Postoperatively she had hematemesis, and endoscopic examination revealed circumferential mucosal necrosis and desquamation of the lower esophagus. She died of multiple organ failure on postoperative day 74. Autopsy demonstrated transmural necrosis of the esophagus secondary to ischemia. Ischemia of the esophagus secondary to aortic dissection is extremely rare.

Preoperative demonstration of the Adamkiewicz artery by magnetic resonance angiography in patients with descending or thoracoabdominal aortic aneurysms.

OBJECTIVE: Investigating the possibility of magnetic resonance angiography (MRA) to visualize the Adamkiewicz artery of as a preoperative study of thoracic aortic aneurysms. METHODS: From February 1998 to March 1999, 26 consecutive patients who had aneurysms of the thoracoabdominal or descending aorta underwent preoperative MRA to visualize the Adamkiewicz artery. Mean age was 60.5+/-11.5 years. Fifteen patients had non-dissecting aneurysm and 11 had aortic dissections. Nineteen patients underwent replacement of the aneurysms, four patients underwent endovascular stent-graft repair, and three patients were discharged without treatment of aneurysm. MRA was performed on a 1.5-T system (Magnetom, Siemens) and data acquisition was repeated two times following injection of gadolinium-DTPA. Source images were reconstructed with multiplanar reconstruction and maximum intensity projection. Criteria for the Adamkiewicz artery of were that the artery ascends from the dorsal branch of the intercostal or lumbar artery to the anterior mid-sagital surface of the spinal cord in the early phase. RESULTS: The Adamkiewicz arteries were demonstrated in 18 patients (69%). These arteries were originated from the left intercostal or lumbar arteries in 13 (72.2%) patients and from the right in 5 (27.8%) and from the Th8 branch in three, Th9 in seven, Th10 in two, Th11 in four, and L1 in two. All patients had graft replacement of the aorta using a partial bypass. All intercostal or lumber arteries, which were visualized as the origin of the Adamkiewicz artery, were reattached to the grafts. No spinal cord injury occurred. CONCLUSION: Preoperative detection the Adamkiewicz artery was possible by MRA and was very useful to reduce the incidence of ischemic injury of the spinal cord during surgery of the thoracoabdominal or descending aorta.

Surgical considerations of occlusive lesions associated with Takayasu's arteritis.

OBJECTIVE: Takayasu's arteritis is an inflammatory vascular disease of unknown etiology that affects the aorta and its main branches, requiring surgical intervention due to occlusive lesions. We studied early and late surgical results. METHODS: Between 1979 and December 1998, 46 patients--1 man and 45 women aged 15 to 72 years (mean: 46 +/- 13 years)--with occlusive lesions caused by Takayasu's arteritis underwent surgery. Preoperative steroids were administered to 22 patients having inflammation. Diagnosis indicating surgery included obstructive cervical vessel disease in 13 patients, obstructive coronary artery disease in 19, aortic coarctation in 15, and abdominal branch stenosis in 3. Surgical procedures involved bypass grafting in 31 (cervical vessel bypass in 13, ascending-abdominal aortic bypass in 4, axillary artery-abdominal aortic bypass in 10, descending-abdominal aortic bypass in 1, abdominal branch bypass in 3), coronary artery bypass grafting in 10, and coronary ostial endarterectomy in 9. RESULTS: Four (8.7%) died during hospitalization. Follow-up ranged from 1 to 240 months (mean: 117 months). Eight suffered late deaths and 6 patients died of cardiovascular problems. The total actuarial survival rate was 76.2% at 5 years and 70.5% at 10 years. CONCLUSIONS: Steroid therapy before and after surgery appears to affect the overall prognosis positively in patients with Takayasu's arteritis.

A surgically treated case of Takayasu's arteritis complicated by aortic dissections localized in the ascending and abdominal aortae.

Because complication by aortic dissection is markedly rare in patients with Takayasu's arteritis, a limited number of reports have been published regarding surgically treated cases of Takayasu's arteritis that is complicated by aortic dissection. When graft replacement of the ascending aorta and aortic arch and extra-anatomic bypass grafting were performed in a 72-year-old japanese woman with Takayasu's arteritis, which was complicated by aortic dissections localized in the ascending and abdominal aortae, the postoperative course of this patient was satisfactory. It was considered that the media became friable in this patient because of the presence of Takayasu's arteritis and that hypertension that persisted for a long time caused the independent development of aortic dissections in the ascending and abdominal aortae.

Three-channeled aortic dissection in Marfan syndrome.

Among the various types of aortic dissection, three-channeled aortic dissection, in which two adjacent false lumens are present, is rarely observed. The authors surgically treated 20 Marfan syndrome patients with this type of dissection, who accounted for 29.4% of 68 patients with aortic dissection in Marfan syndrome and who were surgically treated in the authors' institution prior to July 1999. Patient age ranged from 24 to 51 years (mean of 40 years). The male:female ratio was 13:7. Valved conduit procedure had been performed previously in 14 patients. Pain was observed at various times in 13 patients. Computed tomography scanning and magnetic resonance imaging were useful for preoperative diagnosis. The morphology of the first and second false lumens was Stanford type A + type B in 10 patients and type B + type B in 10 patients. Re-entry of the second false lumen was observed in five patients. The descending aorta was replaced in 13 patients, thoracoabdominal aortic replacement was performed in five, extra-anatomic bypass in one patient and iliac artery-superior mesenteric artery bypass in one. Four patients died in hospital. There were three late deaths during a follow-up of 1-208 months (mean of 51 months). When pain recurs in Marfan patients with aortic dissection, three-channeled dissection should be suspected and subsequent surgery is required. The incidence of this dissection is high in patients with Marfan syndrome.

Native heart complications after heterotopic heart transplantation: insight into the potential risk of left ventricular assist device.

BACKGROUND: In heterotopic heart transplantation, the donor heart is connected parallel to the recipient's diseased heart. Recipients continue to have risks, such as arrhythmia, thromboembolism, valvular heart disease, and ischemic heart disease which can develop in the native heart. It may serve as a clinical model to study long-term pathophysiologic processes in the native heart of patients with a left ventricular assist device. METHOD: We analyzed the prevalence of long-term complications related to the native heart in the heterotopic heart transplant and attempted to gain insight into the potential risk to a native heart after receiving a left ventricular assist device. RESULTS: Between December 1984 and December 1994, 16 patients (13 men, 3 women, ranging in age from 37 to 60 years) underwent heterotopic heart transplant at the University of Pittsburgh. The 1- and 5-year survival rate after the transplant was 81% and 44%, respectively. Actuarial freedom from complications related to the native heart after 1 year and 4 years was ventricular arrhythmia: 85%, 75%; ischemic disease: 85%, 64%; valvular disease: 100%, 88%; and thromboembolism: 85%, 58%. Of these complications, thromboembolism was not considered in determining actuarial freedom from complications because thromboembolism should be regarded as a device-related complication rather than as a native-heart-related complication for left ventricular assist device recipients. Consequently, actuarial freedom from all complications excluding thromboembolism was 70% after 1 year and 50% after 4 years. In addition, the hazard function curve remains constant up to 80 months after the operation without significant differences among the yearly ratios. CONCLUSIONS: This analysis suggests that cautious observation of the native heart's long-term performance is necessary for the left ventricular assist device recipient.

Is distal anastomosis only to the true channel in chronic type B aortic dissection justified?

BACKGROUND: We investigated long-term outcomes of the distal false lumen of the aorta and aortic branches after distal anastomosis of the graft only to the true lumen in chronic type B aortic dissection. METHODS: From November 1979 until June 1998, we treated 98 patients without Marfan syndrome who had chronic type B aortic dissection and underwent replacement of the descending aorta, 79 of whom had distal anastomosis to the true lumen only. The celiac artery originated from the false lumen in 11 patients, superior mesenteric artery in 5, right renal artery in 19, and left renal artery in 16. RESULTS: There were 12 (15.1%) early deaths. Spinal cord ischemia was detected in 5 patients. Postoperative follow-up was achieved in 67 patients, and 13 patients died. Postoperative survival at 10 years was 67.6% +/- 7.1%. Eight patients had complete occlusion of the distal false lumen, 54 patients had occlusion of the false lumen down to the celiac artery, and 5 patients had a patent false lumen. Four patients required further replacement of the thoracoabdominal aorta. CONCLUSIONS: In non-Marfan patients with chronic type B aortic dissection, the false lumen distal to the graft anastomosis was likely to be thrombosed when the graft was anastomosed to the true lumen only. Postoperative visceral circulation was not compromised, but spinal cord ischemia is a problem that remains to be solved.

Early and long-term results of surgery for aneurysms of the thoracic aorta in septuagenarians and octogenarians.

OBJECTIVE: The purpose of this study was to demonstrate early and long-term results of surgery for thoracic aortic aneurysm in patients over 70 years of age compared with those of patients under 70 years and to clarify the clinical problems peculiar to this subset of patients. PATIENTS AND METHODS: Of 1157 patients who underwent surgery for thoracic aortic aneurysm from 1978 to December 1997, 261 who were 70 years or older were selected for analysis. Mean age at the time of surgery was 74.4 +/- 3.5 years. Aneurysms were atherosclerotic in 177 patients and aortic dissection in 84. Acute aortic dissection was found in 25 patients and ruptured aneurysm in 44. The control group consisted of 896 patients under 70 years. Preoperative complications such as AAA, peripheral arterial disease, emphysema, and old cerebral infraction were more common in the older group. Operative procedures consisted of replacement of the ascending aorta or hemiarch in 51 patients, total arch replacement in 75, distal arch replacement in 35, descending aorta replacement in 75, replacement of the thoracoabdominal aorta in 28, and extra-anatomical repair and others in 15. The technique of extracorporeal circulation was selective cerebral perfusion in 69 patients, deep hypothermic circulatory arrest in 90, femoro-femoral bypass in 39, left heart bypass in 12, and temporary aorto-arterial bypass in 30, and others in 21. RESULT: Early mortality was 21% (54 patients), which was greater than that of the control group (113 patients, 13%, P < 0.01). The incidence of postoperative stroke, transient brain dysfunction, and respiratory problems was higher in the study group (P < 0.01 in all). Mean duration in ICU among survivors was 9.3 +/- 20.2 days and that of the control group was 5.9 +/- 2.8 days (P < 0.01). In a recent series (from 1991 to 1997) postoperative mortality improved to 15.6% (30/192 patients) in the study group however this result was still inferior to that of the control group (8.6%, 39/452, P = 0.03) however mortality of emergency surgery during the same periods was still high (31%, 11/35 patients). Logistic regression analysis revealed that significant risk factors for postoperative hospital death were surgery before 1991, age over 70 years, preoperative cardiac problems, aneurysm rupture, postoperative stroke, low output syndrome, bleeding, and acute renal failure. Postoperative follow-up was obtained in 408 patients/year and the longest period was 10.2 years. Late deaths were documented in 31 patients. Five-year and 10-year survival were 61.2 +/- 5.7% and 31.3 +/- 16.4%, respectively. In the control group the 5-year and 10-year survival were 78.0 +/- 2.1% and 62.5 +/- 4.0%, respectively (P = 0.03). However, survival of the early survivors in the study group was similar with that of the age-matched normal population. Aortic reoperation was performed in 13 patients. Freedom from aortic reoperation was 86.7 +/- 4.2% at 5 years and 80.5 +/- 7.1% at 10 years in the study group and 83.4 +/- 1.8% at 5 years and 64.1 +/- 13.3% at 10 years in the control group (P = 0.27). CONCLUSION: Although recent advances have been achieved, early and long-term results of surgery for thoracic aortic aneurysm in patients older than 70 years were less satisfactory compared with those of patients under 70 years of age, especially in patients who required emergency surgery. Preoperative disorder of the vital organ systems was considered to be the main causative factor for high mortality, however, pertinent surgical strategies are necessary to improve the outcome of elderly patients.

[A case report of total aortic reconstruction and choice of staged operation in Marfan syndrome].

A 37-year-old man with Marfan syndrome underwent four operations for extensive cardiovascular disease. He was diagnosed as having AAE, AR and DeBakey type I aortic dissection. First, Bentall operation using Piehler procedure and total aortic arch replacement using retrograde cerebral perfusion and profound hypothermia at 18 degrees C were performed on May 11, 1994. Second, repair of leakage of the right coronary artery anastomosis and grafting for the descending thoracic aortic aneurysm were performed on December 3, 1994. Y-type grafting for the AAA was performed on December 21, 1996. Last, grafting for TAAA was performed under hypothermia at a rectal temperature of 20 degrees C on November 17, 1997. This surgical strategy of staged operation for extensive cardiovascular disease in Marfan syndrome is an effective method. Regular follow-up by CT is necessary for deciding the time and method of reoperation.

Rotary blood pump flow spontaneously increases during exercise under constant pump speed: results of a chronic study.

Many types of rotary blood pumps and pump control methods have recently been developed with the goal of clinical use. From experiments, we know that pump flow spontaneously increases during exercise without changing pump control parameters. The purpose of this study was to determine the hemodynamics associated with the long-term observation of calves implanted with centrifugal blood pumps (EVAHEART, Sun Medical Technology Research Corporation, Nagano, Japan). Two healthy female Jersey calves were implanted with devices in the left thoracic cavity. A total of 22 treadmill exercise tests were performed after the 50th postoperative day. During exercise, the following parameters were compared with conditions at rest: heart rate, blood pressure, central venous oxygen saturation (SvO2), pump speed, and pump flow. The pump flow in a cardiac cycle was analyzed by separating the systole and diastole. Compared to the base data, statistically significant differences were found in the following interrelated parameters: the heart rate (66.8 +/- 5.2 vs. 106 +/- 9.7 bpm), mean pump flow (4.8 +/- 0.2 vs. 7.0 +/- 0.3 L/min), and volume of pump flow in diastole (26.0 +/- 1.8 vs. 13.5 +/- 2.5 ml). During exercise, the volume of pump flow in systole was 3 times larger than that measured in diastole. Blood pressure, SvO2, and pump speed did not change significantly from rest to exercise. These results suggested that the mean pump flow depends on the systolic pump flow. Therefore, the increase in the mean pump flow during exercise under constant pump speed was caused by an increase in the heart rate.