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J Thorac Cardiovasc Surg 2003;126:1672
© 2003 The American Association for Thoracic Surgery

Letters to the editor

Reply to the editor

Ioannis K. Toumpoulis, MDa, Constantine E. Anagnostopoulos, MDa, George E. Drossos, MDa

a Department of Cardiac Surgery, University Hospital of Ioannina, Ioannina, Greece

We thank Madhavan for his interest in our work. We have addressed these issues as follows, in reverse order:

We did not measure blood pressure and heart rate in the vitamin C group because we were unaware that this would be necessary.1,2 We did measure just the blood pressure before and 2 hours after the oral administration of 2 g vitamin C in 6 volunteers (2 smokers and 4 nonsmokers). We found no change in arterial blood pressure after the administration of 2 g vitamin C, but the heart rate was reduced by 5% to 10% in 4 subjects (2 smokers and 2 nonsmokers). We recommend repetition of this trial by others.

The changes in diameter of the radial artery were statistically significant in all four groups (Table 1). The mean percentage increases in radial diameter were 7.38% in the control group and 18.75% in the smoking group (P = .004 when analyzed by t test or P = .004 when analyzed by Mann-Whitney U test). Also, the mean percentage increases in radial diameter was 15.88% in patients with coronary artery disease who received vitamin C and 7.76% in patients with coronary artery disease who received diltiazem (P = .037 when analyzed by t test or P = .016 when analyzed by Mann-Whitney U test).


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  		TABLE 1. Diameter (expressed in mm) of radial arteries (mean ± SD) at baseline and 2 hours after the oral administration of 2 g vitamin C in four groups of 15 subjects each

 
Lumen surface area measurement was chosen because the Acuson equipment that we used exhibits it (Figure 1 in the original article). With respect to not using the {pi}r2 formula, we assumed that all readers are aware of the meaning of our statement: "All lumen surface areas (derived from the estimated lumen diameter) are expressed in square millimeters" in the Methods section of our article.

Diameter measurements from the original data are given in Table 1 as desired by Madhavan. As to the new findings in Greek patients from a remote mountain region of Epirus, on a typical Mediterranean diet, without discontinuation of multiple medications before the administration of vitamin C, and notably heavy smokers, it appears that vitamin C plus "something" does indeed cause endothelium-independent vasodilation in the radial artery of our patients. In addition, the objective of our work is to protect a vessel that is excessively handled during harvesting for coronary artery bypass grafting.3 Therefore our study with ultrasonographic probing, which may be excessive (as many as 5 minutes of manipulation of the radial artery) does not necessarily imply a systemic effect. Perhaps the study may be furthered by studying other populations and arteries.4,5

References

  1. Hirai N, Kawano H, Hirashima O, Motoyama T, Moriyama Y, Sakamoto T, et al. Insulin resistance and endothelial dysfunction in smokers: effects of vitamin C. Am J Physiol Heart Circ Physiol. 2000;279:H1172–1178[Abstract/Free Full Text]
  2. Duffy SJ, Gokce N, Holbrook M, Hunter LM, Biegelsen ES, Huang A, et al. Effect of ascorbic acid treatment on conduit vessel endothelial dysfunction in patients with hypertension. Am J Physiol Heart Circ Physiol. 2001;280:H528–534[Abstract/Free Full Text]
  3. Rosenfeldt FL, He GW, Buxton BF, Angus JA. Pharmacology of coronary artery bypass grafts. Ann Thorac Surg. 1999;67:878–888[Abstract/Free Full Text]
  4. Hornig B, Arakawa N, Kohler C, Drexler H. Vitamin C improves endothelial function of conduit arteries in patients with chronic heart failure. Circulation. 1998;97:363–368[Abstract/Free Full Text]
  5. Cross JM, Donald AE, Nuttall SL, Deanfield JE, Woolfson RG, Macallister RJ. Vitamin C improves resistance but not conduit artery endothelial function in patients with chronic renal failure. Kidney Int. 2003;63:1433–1442[Medline]

Related Article

Reply to the editor
Mitsunori Ohta, Noriyoshi Sawabata, Hajime Maeda, and Hikaru Matsuda
J. Thorac. Cardiovasc. Surg. 2003 126: 1671. [Extract] [Full Text] [PDF]




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