The principles of metabolic therapy for heart disease

Metabolic therapy involves the administration of a substance normally found in the body to enhance a metabolic reaction within the cell. This may be achieved in two ways. First, for some systems, a substance can be given to achieve greater than normal levels in the body so as to drive an enzymic reaction in a preferred direction. Second, metabolic therapy may be used to correct an absolute or relative deficiency of a cellular component. Thus, metabolic therapy differs greatly from most standard cardiovascular pharmacologic therapy such as the use of ACE Inhibitors b-blockers, statins and calcium channel antagonists that are given to block rather than enhance cellular processes. In this review we highlight some metabolic substances that have potential benefit in treating heart disease or improving outcomes after cardiovascular interventions. Glucose-insulin-potassium therapy is protective against myocardial ischaemia by elevating myocardial glycogen levels. Coenzyme Q(10) is a lipid-soluble antioxidant that plays a crucial role in cellular ATP production. Magnesium orotate, a key intermediate in the biosynthetic pathway of glycogen, has been shown to improve the energy status of the cell and improve recovery from cardioplegic arrest. The amino acid aspartate plays an important role in providing energy substrates for oxidative phosphorylation in the myocyte. By improving cellular energy production, metabolic therapy has the potential to benefit cardiac function during the stress of cardiac surgery, myocardial infarction and cardiac failure.

The Clinical Application of Metabolic Therapy for Cardiovascular Disease

Metabolic therapy involves the administration of a substance normally found in the body to enhance a metabolic reaction within the cell. This may be achieved in two ways. Firstly, for some systems a substance can be given to achieve greater than normal levels in the body so as to drive an enzymic reaction in a preferred direction. Secondly, metabolic therapy may be used to correct an absolute or relative deficiency of a cellular component. Thus, metabolic therapy differs greatly from most standard cardiovascular pharmacologic therapies such as the use of ACE Inhibitors, beta-blockers, statins and calcium channel antagonists that are given to block rather than enhance cellular processes.

OUTCOME AND QUALITY OF LIFE AFTER CARDIAC SURGERY IN OCTOGENARIANS

BACKGROUND

Cardiac surgery is being performed with increasing frequency in octogenarians. The purpose of the present study was to determine the outcome and quality of life of octogenarians after cardiac surgery in a single surgeon series and in a newly established cardiac surgery unit.

METHODS

Prospective data collection and analysis were undertaken of octogenarians having cardiac surgery from 1997 to 2003 by a single surgeon in a single institution. The outcome was compared to septuagenarians operated on by the same surgeon in the same time frame, specifically to see if there were any significant differences in outcomes between these two close age groups. Follow up was conducted by sending a questionnaire, interviewing patients or their general practitioner.

RESULTS

There were significantly less octogenarians with airway disease but more with class III and IV New York Heart Association heart failure. There were no significant differences in the incidence of left main disease, urgent operations, renal impairment and cerebrovascular disease between the two groups. There was a trend towards increased operative mortality in octogenarians when the group was taken as a whole (8%vs 2%, P = 0.052). They also had a significantly higher incidence of respiratory failure (6%vs 2%, P = 0.029). The incidence of stroke, renal failure and low cardiac output was not significantly different between the two groups. Blood product usage was significantly higher in octogenarians (19%vs 9%, P = 0.042), but re-operation for bleeding was not significantly different (3%vs 4%). Intensive care unit median length of stay was significantly longer in the case of Octogenarians (1.0 vs 0.9 days, P = 0.039), but the duration of hospital stay was similar (6.5 vs 6.4 days, P = 0.165). Follow up was 94.5% complete, 85% of the octogenarians responded to the questionnaire sent to them. All patients were free of angina, 98% of them had improved by at least one New York Heart Association heart failure class and 86.7% felt that they were less dependent on others after cardiac surgery. In retrospect, 94.2% said that they would have the procedure again.

CONCLUSION

Octogenarians can be operated on with acceptable mortality and morbidity to achieve significant improvement in quality of life. The outcome of surgery in these patients in a new unit is comparable with established units.

Cardiac surgery in Australian octogenarians: 1996-2001

BACKGROUND

The number of octogenarians receiving cardiac surgery is increasing. Concerns regarding the outcomes and significant expense required to provide this service have not been addressed because no prospective medium term outcomes of Australian octogenarians have been published.

METHODS

Prospective analysis was undertaken of octogenarians having cardiac surgery from 1996 to 2001 in three hospitals of moderate case volume (400 patients per year) by: in-hospital audit and data acquisition, 1-year direct patient follow up in rooms, and a final follow up in late 2001 directly with the patient either in rooms or via telephone questionnaire.

RESULTS

Sixty-four patients had cardiac surgery. All patients were severely disabled by symptoms (CCVS: III-IV, NYHA: III-IV) preoperatively, 14% were advised not to proceed with a surgical option but did so. Total operative in-hospital mortality was 6.3% (elective: 0%, urgent: 10.5%, P = 0.05), major complications were few 10.9% (seven patients; stroke: 1.6%, deep sternal infection: 1.6%, myocardial infarction: 1.6%, reoperation: 4.8%). At 1 year, despite 95% being free of significant cardiovascular symptoms (CCVS/NYHA: I-II), nearly one in five (19%) would not have proceeded with the surgery. However, at the final follow up (mean time: 2.8 years), freedom from cardiovascular symptoms remained high (95%), 94% remained independent and their quality of life was significantly better than before surgery. Although 59% suffered worsening of additional medical conditions, these conditions had a minor impact on their quality of life. Ninety-eight per cent would recommend cardiac surgery. Actuarial survival for all patients and for hospital survivors at 4 years was 67.9 +/- 4.1% and 74.2 +/- 4%, respectively.

CONCLUSION

Medium-term follow up of Australian octogenarians who were offered cardiac surgery revealed that 94% remain independent and with an excellent quality of life. Age alone must not be a barrier to access to cardiac surgery.

Outcomes of cardiac surgery in nonagenarians: a 10-year experience

BACKGROUND

With an increasing awareness of health issues and greater emphasis on preventive medicine, the general population is living longer and healthier lives than ever before. Physicians are taking care of older patients, many of whom may require cardiac surgical procedures. Improving cardiopulmonary bypass technology allows for safer procedures with reduced morbidity and mortality even in older patients.

METHODS

We have performed a retrospective analysis of 42 consecutive nonagenarian patients who underwent open-heart procedures over a 10-year period (1993 to 2002) at our institution. Their demographic profiles, operative data, perioperative results, and long-term outcomes were recorded and analyzed.

RESULTS

Twenty-two women and 20 men with an age range of 90 to 97 years (mean, 91.4 years) had open-heart surgery over the study period. The complication rate was 67% overall, consisting of 7% respiratory (pneumonia, respiratory failure, reintubation), 7% hemorrhagic or embolic (postoperative bleeding, cerebral vascular accident), 12% infectious (wound infection, sepsis), and 31% new arrhythmia (atrial fibrillation, atrial flutter, ventricular tachycardia, ventricular fibrillation). Despite these complication rates, average hospital stay was 17.5 days (median, 11 days), with an intensive care unit stay of 12.0 days (median, 5 days). Thirty-day survival was 95% and survival to discharge was 93% (three deaths total; one cardiac arrest at hospital day 134 and two perioperative deaths; one ventricular arrhythmia, one cerebral vascular accident). The only statistically significant risk factor of mortality was emergency surgery. Currently, 81% are still alive an average of 2.53 years since surgery (range, 0.16 to 7.1 years).

CONCLUSIONS

With improving techniques and greater attention to detail, the select nonagenarian can safely undergo cardiac surgery.

Cardiac surgery in octogenarians--The Green Lane Hospital Experience 1995-1998

BACKGROUND

An increasing number of patients aged 80 years and over are being considered and accepted for cardiac surgery.

AIM

To review the experience of surgery in this elderly group of patients at our institution.

METHODS

Hospital records of octogenarians undergoing surgery between January 1995 and September 1998 were reviewed and follow-up was obtained by general practitioner (GP) and patient questionnaires.

RESULTS

Thirty-seven patients underwent cardiac surgery. The mean age was 82.8+/-1.4 years (range 80.8 to 86.2 years). Twenty-three (62%) were male. All were independent pre-operatively with severe symptoms and minor co-existing morbidity. All operations were urgent except two (emergency). Twenty patients (54%) had isolated coronary surgery, six (16%) aortic valve replacement alone, and 11 (30%) combined surgery. There were four (11%) early deaths and five (14%) peri-operative neurological events. The mean duration of post-operative intensive care stay was 2.4+/-3.9 days (range 0.05 to 16, median 1.0) and post-operative hospital stay 14.0+/-13.9 days (range 0 to 79, median 11). At the time of follow-up (mean duration 20.0+/-11.2 months) two further patients had died (non-cardiac). Twenty-six of the 31 survivors were living at home (23 independently), one with relatives, and four in residential care. Their cardiac symptoms were well controlled. The GPs of all hospital survivors, and all surviving patients themselves, felt that cardiac surgery had been beneficial.

CONCLUSIONS

Cardiac surgery in the very elderly has been reserved for those with severe disease or symptoms and little co-morbidity. Early mortality is higher than for the general population undergoing cardiac surgery, but post-operative resource use is acceptable and the intermediate-term outcome for survivors is good.

Cardiac surgery in octogenarians: can elderly patients benefit? Quality of life after cardiac surgery

BACKGROUND

Increasing numbers of the very old are presenting for cardiac surgical procedures. There is little information about quality of life after hospital discharge in this group.

METHODS

From March 1995 to February 1997, 127 patients older than 80 years at operation (mean age, 83+/-2.5 years; range, 80 to 92 years) were entered into the cardiac surgery database and analyzed retrospectively. The RAND SF-36 Health Survey and the Seattle Angina Questionnaire were used to assess quality of life by telephone interview (mean follow-up, 15.7+/-6.9 months). No patient was lost to follow-up.

RESULTS

Operations included coronary artery bypass grafting (65.4%), coronary artery bypass grafting plus valve replacement (15.8%), and isolated valve replacement (14.2%). Preoperatively, 63.8% were in New York Heart Association class IV. Thirty-day mortality was 7.9%, and actuarial survival was 83% (70% confidence interval, 79% to 87%) at 1 year and 80% (70% confidence interval, 75% to 85%) at 2 years. Preoperative renal failure significantly increased the risk of early death (relative risk, 3.96) as did urgent or emergent operation (relative risk, 6.70). In addition, cerebrovascular disease (relative risk, 3.54) and prolonged ventilation (relative risk, 3.82) were risk factors for late death. Ninety-five patients (92.2%) were in New York Heart Association class I or II at follow-up. Seattle Angina Questionnaire scores for anginal frequency (92.3+/-18.9), stability (94.4+/-16.5), and exertional capacity (86.8+/-25.1) indicated good relief of symptoms. SF-36 scores were equal to or better than those for the general population of age greater than 65 years. Of the survivors, 83.7% were living in their own home, 74.8% rated their health as good or excellent, and 82.5% would undergo operation again in retrospect.

CONCLUSION

Octogenarians can undergo cardiac surgical procedures at a reasonable risk and show remarkable improvement in their symptoms. Elderly patients benefit from improved functional status and quality of life.

[Arterial myocardial revascularization in the 9th decade of life. Personal results and review of the literature]

The rate of the population being 80 years of age and even older, has an increasing tendency in the Federal Republic of Germany. In 1996, a total of 87,372 patients received surgery supported by the heart-lung-machine, 2,383 patients out of these (2.7%) were 80 years of age and older. In view of the limited life expectance, the arterial revascularization in this age category is faced with controverse discussions. We analysed our patients in relation to this aspect. Between January 1, 1995 and June 30, 1997, 4,338 patients underwent surgery supported by the heart-lung-machine. Hundred and fifty-five out of these (3.6%) were in the 9th decade of life. Seventy-seven patients out of the 155 (49.7%, 34 women, 43 men, 80 to 88 years old, mean: 82 years of age) underwent an isolated myocardial revascularization. We performed 55 (71%) elective, 16 (21%) urgent and 6 (8%) emergency surgeries. Twelve patients (15.6%) solely received venous bypasses (Group I), 65 (84.4%) additionally also received unilateral bypasses of the internal mammaria artery (IMA) (Group II). Three patients died at our facility (3.9%), 3 further patients died during the follow-up treatment in outlying hospitals, the in-patient mortality rate in Group I therefore presented a rate of 8.3%, in Group II 7.7% and in total, a rate of 7.8%. In 1996, the in-patient mortality rate could be reduced to 3.6%. The follow-up observation time ranged between 7 and 138 weeks (median 44 weeks). The survival rate for patients with an IMA-bypass after 1 year was 86.3%, after 2 years 77%, and for the entire collective 85.3% and 75%. Whereas 96% of the patients could pre-operatively be related to Class III or IV of the NYHA-classification, 55 of the 63 survivors (87%) belonged to Class I (6%) or II (81%). Two Group I patients (22.2%), 3 Group II patients (5.6%) and 7.9% of the total collective complained about repeated angina symptoms. The myocardial revascularization with the internal mammaria artery performed on patients in the 9th decade of life, achieves an acceptable morbidity and mortality compared to solely venous coronary bypasses. The more prolonged follow-up observation period will clarify, whether the arterial myocardial revascularization also proves to be the superior method in this age category.

Comparison of quality of life after coronary and/or valvular cardiac surgery in patients > or =75 years of age with younger patients

Quality of life after cardiac surgery appeared to be comparable in patients aged > or =75 years and younger patients. Preoperative depression had more impact on postoperative well-being in the elderly compared with younger patients.

Coenzyme Q10 improves the tolerance of the senescent myocardium to aerobic and ischemic stress: studies in rats and in human atrial tissue

The inferior recovery of cardiac function after interventional cardiac procedures in elderly patients compared to younger patients suggests that the aged myocardium is more sensitive to stress. We report two studies that demonstrate an age-related deficit in myocardial performance after aerobic and ischemic stress and the capacity of CoQ10 treatment to correct age-specific diminished recovery of function. In Study 1 the functional recovery of young (4 mo) and senescent (35 mo) isolated working rat hearts after aerobic stress produced by rapid electrical pacing was examined. After pacing, the senescent hearts, compared to young, showed reduced recovery of pre-stress work performance. CoQ10 pretreatment (daily intraperitoneal injections of 4 mg/kg CoQ10 for 6 weeks) in senescent hearts improved their recovery to match that of young hearts. Study 2 tested whether the capacity of human atrial trabeculae (obtained during surgery) to recover contractile function, following ischemic stress in vitro (60 min), is decreased with age and whether this decrease can be reversed by CoQ10. Trabeculae from older individuals (> or = 70 yr) showed reduced recovery of developed force after simulated ischemia compared to younger counterparts (< 70 yr). Notably, this age-associated effect was prevented in trabeculae pretreated in vitro (30 min at 24 degrees C) with CoQ10 (400 MicroM). We measured significantly lower CoQ10 content in trabeculae from > or = 70 yr patients. In vitro pretreatment raised trabecular CoQ10 content to similar levels in all groups. We conclude that, compared to younger counterparts, the senescent myocardium of rats and humans has a reduced capacity to tolerate ischemic or aerobic stress and recover pre-stress contractile performance, however, this reduction is attenuated by CoQ10 pretreatment.

Coenzyme Q10 treatment improves the tolerance of the senescent myocardium to pacing stress in the rat

OBJECTIVE

In elderly patients the results of cardiac interventions are inferior to those in the young. A possible contributing factor is an age-related reduction in cellular energy transduction during the intervention which may induce aerobic or ischemic stress. To investigate whether coenzyme Q10 (CoQ10) improves the response to aerobic stress, functional recoveries of senescent and young rat hearts after rapid pacing were compared with or without CoQ10.

METHODS

Young (4.8 +/- 0.1 months) and senescent (35.3 +/- 0.2 months) rats were given daily intraperitoneal injections of CoQ10 (4 mg/kg) or vehicle for 6 weeks. Their isolated hearts were rapidly paced at 510 beats per minute for 120 min to induce aerobic stress without ischemia.

RESULTS

In senescent hearts pre-pacing cardiac work was 74% and oxygen consumption (MVO2) 66% of that in young hearts. CoQ10 treatment abolished these differences. After pacing, the untreated senescent hearts, compared to young, showed reduced recovery of pre-pacing work, (16.8 +/- 4.3 vs. 44.5 +/- 7.4%; P < 0.01). CoQ10 treatment in senescent hearts improved recovery of work, (48.1 +/- 4.1 vs. 16.8 +/- 4.3%; P < 0.0001) and MVO2 (82.1 +/- 2.8 vs. 61.3 +/- 4.0%; P < 0.01) in treated versus untreated hearts respectively. Post-pacing levels of these parameters in CoQ10 treated senescent hearts were as high as in young hearts.

CONCLUSIONS

(1) Senescent rat hearts have reduced baseline function and reduced tolerance to aerobic stress compared to young hearts. (2) Pre-treatment with CoQ10 improves baseline function of the senescent myocardium and its tolerance to aerobic stress.

Carotid artery surgery in the octogenarian

BACKGROUND

The value of carotid surgery is largely dependent on the safety of the procedure. With changes in population life expectancy, increasing numbers of elderly patients are being considered for surgery.

METHODS

In the present paper, the results of 113 patients (octogenarians: > 80 years of age) who underwent carotid endarterectomy in the 17 years prior to 1994 are reported. This group composed 6.2% of the 1818 patients treated in the period, 665 (36.6%) operations were performed on patients 50-65 years inclusive and 1040 (57.2%) on patients aged 66-80 years inclusive.

RESULTS

The overall peri-operative stroke rate was 2.5% and the postoperative mortality was 1.9% with no statistical difference apparent between the age groups despite hemispheric strokes being the most common indication for operation in the octogenarian group (29.5%) and the least common indication in the youngest age group (16.2%, P <0.01). Long-term follow up (2-7 years) of octogenarian patients undergoing carotid surgery suggested maintenance of pre-operative levels of living independence.

CONCLUSIONS

The results of the study indicated that octogenarian patients should not be denied carotid endarterectomy on the basis of age alone and that results comparable to those of younger patients can be anticipated.

Cardiac surgery in nonagenarians

OBJECTIVES AND BACKGROUND

The purpose of this study was to document our initial experience with patients 90 years of age and older and to determine whether cardiac surgery is justified in this age group. Cardiac surgery in octogenarians has proven to be a successful and worthwhile procedure. A small group of nonagenarians with severe coronary artery disease (CAD) and aortic valve disease refractory to medical therapy have been considered for surgery.

METHODS

Fourteen patients aged 90 or more underwent cardiac surgery for symptomatic CAD or aortic valvular disease refractory to medical therapy. Eight patients underwent isolated coronary artery bypass grafting (CABG) and six patients underwent aortic valve replacement (AVR). All patients were in NYHA Class IV preoperatively.

RESULTS

Hospital mortality occurred in one patient (7%). Hospital morbidity occurred in 10 patients (71%) and included 7 cardiac, 5 neurological, 1 gastrointestinal, 1 infectious, and 1 pulmonary event. All survivors left the hospital symptomatically improved. The mean length of stay was 26 days. Four CABG patients went on to die at a mean of 2 years and 2 months, and 3 remain alive at a mean of 2 years and 4 months. Three AVR patients expired at a mean of 3 years and 4 months, and 3 remain alive at 4 years and 1 month.

CONCLUSIONS

Cardiac surgery in carefully selected nonagenarians is justified and can be performed with acceptable results.