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- Vánky, Farkas B., et al.
(författare)
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Does glutamate influence myocardial and peripheral tissue metabolism after aortic valve replacement for aortic stenosis?
- 2006
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Ingår i: Clinical Nutrition. - : Elsevier BV. - 0261-5614 .- 1532-1983. ; 25:6, s. 913-922
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Tidskriftsartikel (refereegranskat)abstract
- Background & aims Glutamate plays an important role for myocardial metabolism in association with ischaemia. Patients with coronary artery disease characteristically demonstrate increased uptake of glutamate. Improved recovery of myocardial metabolism and haemodynamic state after coronary surgery has been reported in patients treated with glutamate infusion. However, the effect of glutamate has not been studied after other cardiac surgical procedures. In addition, the effects of glutamate on peripheral tissue metabolism remain to be described. Methods Twenty patients undergoing surgery for aortic stenosis were studied after randomisation to blinded infusion of glutamate or saline during 1 h immediately after skin closure. Myocardial and leg tissue metabolism were assessed with organ balance techniques. Results Postoperative glutamate infusion induced a marked increase in myocardial and leg tissue uptake of glutamate. This was associated with a significant uptake of lactate in the heart. The negative arterial–venous differences of amino acids and free fatty acids across the leg were significantly smaller in the glutamate group. Haemodynamic state remained stable and did not differ between groups. Conclusion The heart and peripheral tissues consumed the exogenously administered glutamate after surgery for aortic stenosis. Potentially favourable effects of glutamate on myocardial and peripheral tissue metabolism are suggested.
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- Vanky, Farkas B, et al.
(författare)
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Long-Term Consequences of Postoperative Heart Failure After Surgery for Aortic Stenosis Compared With Coronary Surgery
- 2007
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Ingår i: Annals of Thoracic Surgery. - : Elsevier BV. - 0003-4975 .- 1552-6259. ; 83:6, s. 2036-2043
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Tidskriftsartikel (refereegranskat)abstract
- Background: Although postoperative heart failure is a major determinant of operative mortality in cardiac surgery it has received little attention in the literature, and long-term consequences remain to be addressed. Therefore, the impact of postoperative heart failure on long-term survival in relation to other risk factors was studied. Methods: All patients undergoing aortic valve replacement (AVR) for aortic stenosis from 1995 through 2000 in the southeast region of Sweden (n = 398) were compared with a cohort, matched for age and sex, undergoing coronary artery bypass grafting (CABG [n = 398]). Risk factors for 5-year mortality were analyzed. Results: Forty-five AVR and 47 CABG patients required treatment for postoperative heart failure. Thirty-day, 1-year, and 5-year mortality in patients with and without postoperative heart failure after AVR were 6.7% versus 1.4% (p = 0.05), 8.9% versus 4.0% (p = 0.13), and 42.2% versus 14.2% (p < 0.0001) respectively. Corresponding results in the CABG group were 21.3% versus 1.1% (p < 0.0001), 25.5% versus 3.1% (p < 0.0001), and 36.2% versus 11.1% (p = 0.0015). Postoperative heart failure, preoperative renal dysfunction, procedure-associated stroke, body mass index less than 19 kg/m2, older age, preoperative atrial fibrillation, and preoperative anemia turned out as independent risk factors for 5-year mortality after AVR. In the CABG group, postoperative heart failure, diabetes mellitus, older age, and procedure-associated stroke emerged as independent risk factor for 5-year mortality. Conclusions: Postoperative heart failure was associated with high early mortality after CABG whereas the grave consequences of postoperative heart failure after AVR for aortic stenosis became evident only with time. © 2007 The Society of Thoracic Surgeons.
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- Vánky, Farkas B., et al.
(författare)
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Myocardial metabolism before and after valve replacement for aortic stenosis
- 2006
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Ingår i: Journal of Cardiovascular Surgery. - 0021-9509 .- 1827-191X. ; 47:3, s. 305-313
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Tidskriftsartikel (refereegranskat)abstract
- AIM: Post ischemic disturbances of myocardial metabolism that may contribute to postoperative heart failure and are accessible to metabolic treatment have been identified early after coronary surgery. Knowledge derived from these studies may not be applicable to other patient groups. Therefore we studied myocardial energy metabolism in patients operated for isolated aortic stenosis. METHODS: Twenty patients undergoing isolated aortic valve replacement (AVR) because of aortic stenosis without significant regurgitation were studied before and immediately after surgery. Myocardial uptake of oxygen and energy substrates was assessed with coronary sinus catheter technique. RESULTS: Free fatty acids (FFA) were the main source of myocardial energy before and after AVR. A significant uptake of lactate was only recorded preoperatively. A significant uptake of glutamate of the same magnitude as previously described in coronary patients was found pre- and postoperatively. Postoperatively a relative decrease of myocardial oxygen extraction ratio (P<0.001) and oxygen consumption (P=0.14) by approximately 20% was observed. CONCLUSION: Preoperative and postoperative metabolic adaptation with substantial uptake of glutamate, previously claimed to be due to chronic or repetitive ischemia, was demonstrated. The results indicate that oxidative metabolism had not fully recovered when the procedure was completed. However, the potentially unfavorable postoperative metabolic state with predominant reliance on FFA as energy source was out-balanced by the unloading effect of AVR with a reduction in myocardial oxygen extraction.
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- Vánky, Farkas B., et al.
(författare)
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Risk factors for postoperative heart failure in patients operated on for aortic stenosis
- 2006
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Ingår i: The Annals of Thoracic Surgery. - : Elsevier BV. - 0003-4975. ; 81:4, s. 1297-1304
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Tidskriftsartikel (refereegranskat)abstract
- Background Risk factors for postoperative heart failure (PHF) have not been specifically studied in valve surgery although it has been acknowledged that patient variables may have a more profound influence on postoperative outcome than valve-related factors. Methods All patients undergoing isolated aortic valve replacement for aortic stenosis from January 1995 to December 2000 in the southeast region of Sweden were studied (n = 398). Forty-five patients with aortic valve replacement required treatment for PHF. Univariate and multivariate logistic regression analysis was carried out to identify risk factors for PHF. Results Thirty-day mortality was 6.7% versus 1.4% for patients with and without PHF, respectively (p = 0.05). With regard to clinical presentation of aortic stenosis, angina was associated with reduced risk, whereas history of congestive heart failure increased the risk for PHF. Five preoperative (hypertension, history of congestive heart failure, severe systolic left ventricular dysfunction, pulmonary hypertension, preoperative hemodynamic instability) and two intraoperative (aortic cross-clamp time, intraoperative myocardial infarction) variables were identified as independent risk factors for PHF. Patient–prosthesis mismatch did not influence the risk of PHF significantly. Conclusions Postoperative heart failure was associated with a marked increase in postoperative mortality and morbidity. Risk factors for PHF were variables indicating preexisting myocardial dysfunction, increased right or left ventricular afterload, and intraoperative myocardial injury. Our results highlight issues concerning cross-clamp time and myocardial protection, particularly for patients with preoperatively compromised myocardial function. Asymptomatic patients with significant aortic stenosis should be considered for surgery before substantial echocardiographic evidence of left ventricular dysfunction or increased pulmonary artery pressure develops.
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- Vánky, Farkas, 1964-
(författare)
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Surgery for aortic stenosis : with special reference to myocardial metabolism, postoperative heart failure and long-term outcome
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Postoperative heart failure (PHF) remains a major determinant of the outcome after cardiac surgery. However, characteristics of and risk factors for PHF after valve surgery have received little attention.Post-ischaemic disturbances of myocardial metabolism that may contribute to PHF and are amenable to metabolic treatment have been identified early after coronary surgery (CABG). Knowledge derived from these studies may not be applicable to other patient groups. We therefore studied myocardial energy metabolism in 20 elective patients undergoing aortic valve replacement (AVR) for isolated aortic stenosis (AS). The metabolic studies indicated that myocardial oxidative metabolism had not fully recovered when the procedure was completed. Free fatty acids were the only major substrates taken up by the heart. Signs of preoperative and postoperative metabolic adaptation with substantial uptake of glutamate, previously demonstrated in patients with coronary artery disease, were found. Postoperative infusion of glutamate, (2 mL/kg body weight and hour of 0.125 M solution) based on assessment of myocardial glutamate requirements in CABG patients, resulted in a two-fold increase in myocardial glutamate uptake and a seven-fold increase in AV differences across the leg. This was associated with a significant myocardial uptake of lactate and metabolic changes in the leg suggesting mitigation of net amino acid loss and peripheral tissue lipolysis.Characteristics of and risk factors for PHF were evaluated in 398 patients undergoing isolated AVR for AS from 1 January 1995 to 31 December 2000. These were compared with 398 patients, matched for age and sex, undergoing on-pump isolated CABG. Forty-five AVR and 47 CABG patients fulfilled criteria for PHF and these were studied in detail. PHF usually presented at weaning from cardiopulmonary bypass. After CABG it was closely associated with preoperative ischaemic events and intraoperatively acquired myocardial infarction. Potential causes and eliciting events of PHF after AVR for AS were obvious only in one-third of the patients. Risk factors for PHF after AVR for AS indicated either pre-existing myocardial dysfunction, increased right or left ventricular after-load, or intraoperatively acquired myocardial injury. PHF was associated with high early mortality after CABG, whereas the consequences of PHF after AVR for AS became evident only with time, resulting in a 42% five-year mortality. Although PHF had a different temporal impact on late mortality after CABG and AVR for AS, it emerged as the statistically most significant risk factor for mortality occurring within 5 years from surgery both after AVR for AS and after CABG. Potential implications of our findings include needs for greater focus on preoperative surveillance of patients with AS for optimal timing of surgery, mitigation of intraoperatively acquired myocardial injury and tailoring of treatment for PHF. Furthermore, the findings have implications for long-term follow up of AS patients after surgery.
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