Annotations
5.
6.
7.
8.
ischemic injury during cardiopulmonary bypass, Surgery 80:266, 1976. Ramsey, L. H., Puckett, W., Jose, A., and Lacy, W. W.: Pericapillary gas and water distribution volumes of the lung calculated from multiple indicator dilution curves, Circ. Res. 15:275, 1964. Buckberg, G. D., Towers, B., Paglia, D. E., Mulder, D. G., and Maloney, J. V.: Subendocardial ischemia after cardiopulmonary bypass, J. Thorac. Cardiovasc. Surg 64:669, 1972. Najafi, H., Lal, R., Khalili, M., Serry, C., Rogers, A., and Haklin, M.: Left ventricular hemorrhagic necrosis, Ann. Thorac. Surg. 12:440, 1971. Hottentrott, C. E., Towers, B., Kurkji, H. J., Maloney, J. V., Jr., and Buckbery, G.: The hazard of ventricular fibrillation in hypertrophied ventricles during cardiopulmonary bypass, J. Thorac. Cardiovasc. Surg. 66:742, 1973.
Diet in the Coronary
10.
11.
12.
Engelman, R. E., Levitsky, S., and Wyndham, Christopher, R. C.: Optimal conditions for reperfusion during cardiopulmonary bypass, Circulation 66(Suppl. 2):148, 1977. Griepp, R. B., Stinson, E. B., Oyer, P. E., Copeland, J. G., and Shumway, N. E.: The superiority of aortic crossclamping with profound local hypothermia for myocardial protection during aorta-coronary bypass grafting, J. Thorac. Cardiovasc. Surg. 70:995, 1975. Nelson, R. L., Fey, K. H., Follette, D. M., Livesay, J. J., Deland, E., Maloney, J. V., Jr., and Buckberg, G. D.: The critical importance of intermittent infusion of cardioplegic solution during aortic cross-clamping, Surg. Forum 27:241, 1976. Olinger, G. N., PO., J., Maloney, J. V., Jr., Muldner, D. G., and Buckberg, G. D.: Coronary revascularization in “high” versus “low-risk” patients: the role of myocardia; protection, Ann. Surg. 182:293, 1975.
Care Unit*
Despite the fact that in 1970 a poll of 3,600 doctors revealed 90 per cent to favor some form of diet therapy for their CCU patients,’ great confusion persists over what diet is best. We surveyed over 290 major medical centers using a questionnaire and asked chief dietitians if doctors used a routine CCU diet for the first 24 to 72 hours of admission. If the answer was negative, they were asked to fill out the remainder of the questionnaire using the most common diet ordered in the setting of acute myocardial infarction. No distinction was made between the first eight to twenty-four hours (where admittedly many patients receive nothing by mouth as their condition is stabilized) and the remaining 48 to 60 hours of the “acute” phase of coronary care.
Results Seventy-one per cent of the 290 institutions polled responded. About 60 per cent of dietitians acknowledged the use of a “routine CCU diet.” Caloric intake was evenly distributed across a wide range of choices: less than 1,000 calories in 13 per cent of cases; 1,000 to 2,000 calories in 8.5 per cent; 1,200 to 1,400 in 20.5 per cent; 1,400 to 1,600 in 16 per cent; 1,609 to 2,000 in 20 per cent; greater than 2,000 calories per day in 5.5 per cent; and variable intake in 16.5 per cent. Only about half of these diets were bland. Most institutions clearly favor three meals per day (64 per cent), although significant numbers of patients (25.5 per cent) receive multiple small feedings or snacks. While the majority of diets restrict cholesterol or saturated fat (65 per cent), roughly 22 per cent of these restrict cholesterol only. Salt restriction in the form of a 2g Na+ diet was restricted in almost 50 per cent of cases, although nearly 20 per cent of diets contain either no salt restriction or merely no added salt (about 4 Gm. of sodium). Overwhelmingly, CCU diets contain no potassium restriction. About half reduce roughage, either via low bulk foods or
*The opinions or assertions contained herein are those of the authors and are not to be construed as official or necessarily reflecting the views of the Medical Department of the Navy or the Naval Service at large.
130
9.
liquids, and relatively few (10 per cent) restrict carbohydrates. From this data we may infer that no consensus exists regarding what to feed the CCU patient. In fact, very little is known about the advantages and liabilities of different diets. It has been shown that many myocardial infarction patients consume less than 200 calories a day in the CCU. Such starvation diets may result in profound hypoglycemia: a cause of increased cardiac work;’ angina, or myocardial necro~is.‘-~ On the other hand, our data suggest that 40 per cent of hospitals feed their patients meals containing over 1,400 calories per day. Add to this at least 200 calories from “keepopen” intravenous solutions of dextrose and water, and it is apparent that many patients will arbitrarily be “overfed.” This may, at least theoretically, be attended by angina due to increased cardiac output with splanchnic dilatation. Intuitively, such problems might be lessened by the use of small frequent feedings, although there has been no clinical study to support this. Similarly, the bland diet, which our data shows to have wide acceptance, has not been proved to have any special physiologic merit. In individual cases it may be prudent to restrict foods known to be tolerated poorly. Similarly, cardiac stimulants are perhaps best avoided since they may increase heart rate and myocardial oxygen consumption. Hot and cold beverages, however, have been allowed with impunity without ill effects.’ Most CCU diets restrict fat and cholesterol, presumably because of the myocardial depressant effects of free fatty acids and the well-known association of lipids and coronary artery disease. However, it is curious that 22 per cent of diets contain restrictions in cholesterol only. It has been shown that the blood level of cholesterol is more susceptible to influence by the quantity and quality of fat in the diet than by the amount of cholesterol in it.* Cholesterol absorption from the bowel is dependent upon dietary fat intake.R Therefore, it does not make sense to restrict cholesterol without concurrently restricting dietary fat, especially saturated fat. How much salt should the CCU diet contain? Our question-
January,
1978, Vol. 95, No. 1
Annotations
naire shows that roughly half the country favors the 2 Gm. sodium diet. This practice presumably derives from earlier data that demonstrated decreased renal blood flow in congestive heart failure with secondary retention of salt and water. This degree of sodium restriction may be dangerous for many reasons, principally that in the presence of decreased cardiac output loss of extracellular sodium chloride may further decrease output.” An argument can also be made against unlimited salt intake since some Americans habitually consume large amounts of salt with their meals, and the risk of fluid overload and congestive heart failure in the presence of acute myocardial infarction is real. A reasonable compromise would appear to be a “no added salt diet,” which in most hospitals contain 3 to 4 Gm. of sodium, with alterations made according to clinical status. Over 90 per cent of institutions in our sample have no potassium restriction or supplementation in their CCU diets. This is probably due to an appreciation of the lability of serum potassium levels in situations of changing fluid status, acidosis, diuretic therapy, vomiting, and the like, with the need for frequent reassessment. Potassium liberalization would be helpful in the presence of hypokalemia, commonly due to frequent diuretic use, while potassium restriction would be appropriate where there is severe hyperkalemia or renal failure. No generalization about what constitutes optimal potassium intake is possible. Should bulk be restricted in the Coronary Care Unit diet? Liquid diets may reduce the risk of cardiac arrest by avoidance of the vasovagal and arrhythmia-producing effects of gasping or of straining during bowel movements. They may also reduce aspiration.‘” On the other hand, some patients find liquid or low bulk diets constipating, and under these circumstances increased bulk may be more desirable. Again, no universal recommendation regarding optimal bulk in the CCU diet can be made. Lastly, the topic of carbohydrate restriction was surveyed. Fully 30 per cent of institutions responding did not restrict carbohydrates in the Coronary Care Unit diet. We know of no data to support or refute this practice, but since glucose has been shown to be an important fuel source for the acutely I’ there seems to be no good reason to ischemic myocardium, selectively limit carbohydrate intake in the CCU. In conclusion, we have demonstrated widely differing practices in Coronary Care Unit diet therapy in the United States. Caloric intake should be individualized, and extremes such as overfeeding, which may predispose the patient to angina, or near-starvation diets, which predispose to hypoglycemia, are to be avoided. The diet should eliminate items likely to cause gastrointestinal intolerance in specific patients and be comfortably modified in bulk, ideally with multiple small feedings. Both cholesterol and fat should probably be limited.
American
Heart
Journal
Optimal salt intake will vary, but for uncomplicated cases a “no added salt” diet seems reasonable. Depending on circumstances, there may be benefit from increased or decreased dietary potassium. Metabolic needs of the infarction patient must be assessed daily, supplemented by regular determinations of clinical status, intake, output, serum glucose and electrolytes, and by act,ive consultation with the dietitian. Perhaps most important, what is needed is more scientifically determined information about how dietary intake during acute myocardial infarction affects cardiac metabolism and the clinical course of the CCU patient.
S. E. Warren, Lt., MC, USNR J. S. Alpert, Lt. Cdr., MC, USNR G. S. Francis, Lt. Cdr., MC, USNR Cardiology Division Dept. of Internal Medicine Naval Regional Medical Center San Diego, Calif. 92134 REFERENCES 1.
2.
3.
8. 9.
10.
11.
Wenger, N. K., Hellerstein, H. K., Blackburn, H., and Castranova, S. J.: Uncomplicated myocardial infarction. Current physician practice in patient management, J.A.M.A. 224:513, 1973. Feldschuh, J., and Yuceoglu, Y. Z.: Study of daily caloric intake of patients in the coronary intensive care unit, Angiology 26:334, 1975. Ernstene, A. C., and Altschule, M. D.: The effect of insulin hypoglycemia on the circulation, J. Clin. Invest. 10521-527, 1931. Friedberg, C. K.: Diseases of the Heart, 3rd ed., Philadelphia, 1966, W. B. Saunders Co., pp. 1661. Blotner H.: Coronary disease in diabetes mellitus, N. Engl. J. Med. 203:709, 1930. Turner, K. B.: Insulin shock as the cause of cardiac pain, AM. HEART J. 5:671, 1931. Cohen, I. M., Alpert, J. S., Francis, G. S., Vieweg, W. V. R., and Hagan, A. D.: Safety of hot and cold liquids in patients with acute myocardial infarction, Chest 7 1:450, 1977. Jones, R.: The way to a man’s heart. . attack, Ill. Med. J. Aug., 1973, pp. 125-126. Goldberger, E.: Dangers of a low sodium diet in the treatment of acute myocardial infarction, Am. J. Cardiol. 8:300, 1961. Christakes, G., and Winston, M.: Nutritional therapy in acute myocardial infarction, J. Am. Diet. Assoc. 63:235, 1973. Opie, L. H.: Metabolic response during impending myocardial infarction. I. Relevance of studies of glucose and free fatty acid metabolism in animals, Circulation 45:483, 1972.
131
5.
6.
7.
8.
ischemic injury during cardiopulmonary bypass, Surgery 80:266, 1976. Ramsey, L. H., Puckett, W., Jose, A., and Lacy, W. W.: Pericapillary gas and water distribution volumes of the lung calculated from multiple indicator dilution curves, Circ. Res. 15:275, 1964. Buckberg, G. D., Towers, B., Paglia, D. E., Mulder, D. G., and Maloney, J. V.: Subendocardial ischemia after cardiopulmonary bypass, J. Thorac. Cardiovasc. Surg 64:669, 1972. Najafi, H., Lal, R., Khalili, M., Serry, C., Rogers, A., and Haklin, M.: Left ventricular hemorrhagic necrosis, Ann. Thorac. Surg. 12:440, 1971. Hottentrott, C. E., Towers, B., Kurkji, H. J., Maloney, J. V., Jr., and Buckbery, G.: The hazard of ventricular fibrillation in hypertrophied ventricles during cardiopulmonary bypass, J. Thorac. Cardiovasc. Surg. 66:742, 1973.
Diet in the Coronary
10.
11.
12.
Engelman, R. E., Levitsky, S., and Wyndham, Christopher, R. C.: Optimal conditions for reperfusion during cardiopulmonary bypass, Circulation 66(Suppl. 2):148, 1977. Griepp, R. B., Stinson, E. B., Oyer, P. E., Copeland, J. G., and Shumway, N. E.: The superiority of aortic crossclamping with profound local hypothermia for myocardial protection during aorta-coronary bypass grafting, J. Thorac. Cardiovasc. Surg. 70:995, 1975. Nelson, R. L., Fey, K. H., Follette, D. M., Livesay, J. J., Deland, E., Maloney, J. V., Jr., and Buckberg, G. D.: The critical importance of intermittent infusion of cardioplegic solution during aortic cross-clamping, Surg. Forum 27:241, 1976. Olinger, G. N., PO., J., Maloney, J. V., Jr., Muldner, D. G., and Buckberg, G. D.: Coronary revascularization in “high” versus “low-risk” patients: the role of myocardia; protection, Ann. Surg. 182:293, 1975.
Care Unit*
Despite the fact that in 1970 a poll of 3,600 doctors revealed 90 per cent to favor some form of diet therapy for their CCU patients,’ great confusion persists over what diet is best. We surveyed over 290 major medical centers using a questionnaire and asked chief dietitians if doctors used a routine CCU diet for the first 24 to 72 hours of admission. If the answer was negative, they were asked to fill out the remainder of the questionnaire using the most common diet ordered in the setting of acute myocardial infarction. No distinction was made between the first eight to twenty-four hours (where admittedly many patients receive nothing by mouth as their condition is stabilized) and the remaining 48 to 60 hours of the “acute” phase of coronary care.
Results Seventy-one per cent of the 290 institutions polled responded. About 60 per cent of dietitians acknowledged the use of a “routine CCU diet.” Caloric intake was evenly distributed across a wide range of choices: less than 1,000 calories in 13 per cent of cases; 1,000 to 2,000 calories in 8.5 per cent; 1,200 to 1,400 in 20.5 per cent; 1,400 to 1,600 in 16 per cent; 1,609 to 2,000 in 20 per cent; greater than 2,000 calories per day in 5.5 per cent; and variable intake in 16.5 per cent. Only about half of these diets were bland. Most institutions clearly favor three meals per day (64 per cent), although significant numbers of patients (25.5 per cent) receive multiple small feedings or snacks. While the majority of diets restrict cholesterol or saturated fat (65 per cent), roughly 22 per cent of these restrict cholesterol only. Salt restriction in the form of a 2g Na+ diet was restricted in almost 50 per cent of cases, although nearly 20 per cent of diets contain either no salt restriction or merely no added salt (about 4 Gm. of sodium). Overwhelmingly, CCU diets contain no potassium restriction. About half reduce roughage, either via low bulk foods or
*The opinions or assertions contained herein are those of the authors and are not to be construed as official or necessarily reflecting the views of the Medical Department of the Navy or the Naval Service at large.
130
9.
liquids, and relatively few (10 per cent) restrict carbohydrates. From this data we may infer that no consensus exists regarding what to feed the CCU patient. In fact, very little is known about the advantages and liabilities of different diets. It has been shown that many myocardial infarction patients consume less than 200 calories a day in the CCU. Such starvation diets may result in profound hypoglycemia: a cause of increased cardiac work;’ angina, or myocardial necro~is.‘-~ On the other hand, our data suggest that 40 per cent of hospitals feed their patients meals containing over 1,400 calories per day. Add to this at least 200 calories from “keepopen” intravenous solutions of dextrose and water, and it is apparent that many patients will arbitrarily be “overfed.” This may, at least theoretically, be attended by angina due to increased cardiac output with splanchnic dilatation. Intuitively, such problems might be lessened by the use of small frequent feedings, although there has been no clinical study to support this. Similarly, the bland diet, which our data shows to have wide acceptance, has not been proved to have any special physiologic merit. In individual cases it may be prudent to restrict foods known to be tolerated poorly. Similarly, cardiac stimulants are perhaps best avoided since they may increase heart rate and myocardial oxygen consumption. Hot and cold beverages, however, have been allowed with impunity without ill effects.’ Most CCU diets restrict fat and cholesterol, presumably because of the myocardial depressant effects of free fatty acids and the well-known association of lipids and coronary artery disease. However, it is curious that 22 per cent of diets contain restrictions in cholesterol only. It has been shown that the blood level of cholesterol is more susceptible to influence by the quantity and quality of fat in the diet than by the amount of cholesterol in it.* Cholesterol absorption from the bowel is dependent upon dietary fat intake.R Therefore, it does not make sense to restrict cholesterol without concurrently restricting dietary fat, especially saturated fat. How much salt should the CCU diet contain? Our question-
January,
1978, Vol. 95, No. 1
Annotations
naire shows that roughly half the country favors the 2 Gm. sodium diet. This practice presumably derives from earlier data that demonstrated decreased renal blood flow in congestive heart failure with secondary retention of salt and water. This degree of sodium restriction may be dangerous for many reasons, principally that in the presence of decreased cardiac output loss of extracellular sodium chloride may further decrease output.” An argument can also be made against unlimited salt intake since some Americans habitually consume large amounts of salt with their meals, and the risk of fluid overload and congestive heart failure in the presence of acute myocardial infarction is real. A reasonable compromise would appear to be a “no added salt diet,” which in most hospitals contain 3 to 4 Gm. of sodium, with alterations made according to clinical status. Over 90 per cent of institutions in our sample have no potassium restriction or supplementation in their CCU diets. This is probably due to an appreciation of the lability of serum potassium levels in situations of changing fluid status, acidosis, diuretic therapy, vomiting, and the like, with the need for frequent reassessment. Potassium liberalization would be helpful in the presence of hypokalemia, commonly due to frequent diuretic use, while potassium restriction would be appropriate where there is severe hyperkalemia or renal failure. No generalization about what constitutes optimal potassium intake is possible. Should bulk be restricted in the Coronary Care Unit diet? Liquid diets may reduce the risk of cardiac arrest by avoidance of the vasovagal and arrhythmia-producing effects of gasping or of straining during bowel movements. They may also reduce aspiration.‘” On the other hand, some patients find liquid or low bulk diets constipating, and under these circumstances increased bulk may be more desirable. Again, no universal recommendation regarding optimal bulk in the CCU diet can be made. Lastly, the topic of carbohydrate restriction was surveyed. Fully 30 per cent of institutions responding did not restrict carbohydrates in the Coronary Care Unit diet. We know of no data to support or refute this practice, but since glucose has been shown to be an important fuel source for the acutely I’ there seems to be no good reason to ischemic myocardium, selectively limit carbohydrate intake in the CCU. In conclusion, we have demonstrated widely differing practices in Coronary Care Unit diet therapy in the United States. Caloric intake should be individualized, and extremes such as overfeeding, which may predispose the patient to angina, or near-starvation diets, which predispose to hypoglycemia, are to be avoided. The diet should eliminate items likely to cause gastrointestinal intolerance in specific patients and be comfortably modified in bulk, ideally with multiple small feedings. Both cholesterol and fat should probably be limited.
American
Heart
Journal
Optimal salt intake will vary, but for uncomplicated cases a “no added salt” diet seems reasonable. Depending on circumstances, there may be benefit from increased or decreased dietary potassium. Metabolic needs of the infarction patient must be assessed daily, supplemented by regular determinations of clinical status, intake, output, serum glucose and electrolytes, and by act,ive consultation with the dietitian. Perhaps most important, what is needed is more scientifically determined information about how dietary intake during acute myocardial infarction affects cardiac metabolism and the clinical course of the CCU patient.
S. E. Warren, Lt., MC, USNR J. S. Alpert, Lt. Cdr., MC, USNR G. S. Francis, Lt. Cdr., MC, USNR Cardiology Division Dept. of Internal Medicine Naval Regional Medical Center San Diego, Calif. 92134 REFERENCES 1.
2.
3.
8. 9.
10.
11.
Wenger, N. K., Hellerstein, H. K., Blackburn, H., and Castranova, S. J.: Uncomplicated myocardial infarction. Current physician practice in patient management, J.A.M.A. 224:513, 1973. Feldschuh, J., and Yuceoglu, Y. Z.: Study of daily caloric intake of patients in the coronary intensive care unit, Angiology 26:334, 1975. Ernstene, A. C., and Altschule, M. D.: The effect of insulin hypoglycemia on the circulation, J. Clin. Invest. 10521-527, 1931. Friedberg, C. K.: Diseases of the Heart, 3rd ed., Philadelphia, 1966, W. B. Saunders Co., pp. 1661. Blotner H.: Coronary disease in diabetes mellitus, N. Engl. J. Med. 203:709, 1930. Turner, K. B.: Insulin shock as the cause of cardiac pain, AM. HEART J. 5:671, 1931. Cohen, I. M., Alpert, J. S., Francis, G. S., Vieweg, W. V. R., and Hagan, A. D.: Safety of hot and cold liquids in patients with acute myocardial infarction, Chest 7 1:450, 1977. Jones, R.: The way to a man’s heart. . attack, Ill. Med. J. Aug., 1973, pp. 125-126. Goldberger, E.: Dangers of a low sodium diet in the treatment of acute myocardial infarction, Am. J. Cardiol. 8:300, 1961. Christakes, G., and Winston, M.: Nutritional therapy in acute myocardial infarction, J. Am. Diet. Assoc. 63:235, 1973. Opie, L. H.: Metabolic response during impending myocardial infarction. I. Relevance of studies of glucose and free fatty acid metabolism in animals, Circulation 45:483, 1972.
131
