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Retrograde internal mammary artery implantation
Retrograde internal mammary artery implantation Ary Blesovsky, F.R.C.S.* Cedric W. Deal, F.R.C.S.,** William J. Kerth, and Frank Gerbode, M.D.,**** San Francisco, Calif.
A renewed interest in revascularization of the heart has been stimulated by the development of coronary cineangiography1 and the angiographic demonstration of the high incidence of patency of the internal mammary artery after implantation into the heart.- Since the successful revascularization of the anterior part of the left ventricle, attention has been directed to the posterior myocardium to which the Vineberg procedure is not applicable.3 Many methods to revascularize this part of the heart are being tried in experimental From the Department of Cardiovascular Surgery, Presbyterian Medical Center, and the Institute of Medical Sciences, San Francisco, Calif. Aided in part by grants from U. S. Public Health Service, HE 5.149 and HE 06311. Received for publication Sept. 12, 1966. *Fellow, Department of Cardiovascular Surgery, Presbyterian Medical Center, and Department of Surgery, Stanford University School of Medicine, Palo Alto, Calif. Evarts A. Graham Travelling Fellow for 19651966 (sponsored by the American Association for Thoracic Surgery), and holder of a travelling grant from The Wellcome Trust, London, England. **Fellow, Department of Cardiovascular Surgery, Presbyterian Medical Center, and the Institute of Medical Sciences, San Francisco, Calif., and the Department of Surgery, Stanford University School of Medicine, Palo Alto, Calif., and Bay Area Heart Research Award. ***Director of Surgical Laboratory and Associate of Department of Cardiovascular Surgery, Presbyterian Medical Center, and the Institute of Medical Sciences, San Francisco, Calif. ****Chief of Cardiovascular Surgery, Presbyterian Medical Center, and the Institute of Medical Sciences, San Francisco, Calif., and Clinical Professor of Surgery, Stanford University School of Medicine, Palo Alto, Calif.
556
M.D.***
and clinical trials. We wish to report the results of experimental retrograde implantation of the internal thoracic (mammary) artery in a series of 11 dogs. This method was evaluated because of the accessibility of the vessel. Method Ameroid constrictors were placed on the right coronary and the circumflex branch of the left coronary arteries. The left internal mammary artery was freed by ligation or coagulation of side branches from its origin to the level of the fifth rib. It was transected proximally after ligation at its origin from the subclavian artery. In some dogs, simultaneous pressures were recorded in the distal part of the artery immediately after ligation and in the aorta (Table I ) . The mean pressure in the internal mammary averaged two thirds that in the aorta—the pulse pressure did not exceed 10 mm. Hg, and often the flow was not pulsatile. In a few dogs the vessel was allowed to bleed into a flask for 1 minute and the flow was measured (Table II). Flow was uniformly low when compared with flows of 160 to 200 ml. per minute from the distal end of an internal mammary artery freed of its intercostal branches from the second to the sixth intercostal spaces. The divided end of the vessel was ligated after taking pressure and flow measure-
Volume 53 Number 4 April, 1967
Retrograde internal mammary artery implantation
Table I. Retrograde mammary implant pressures (mm. Hg) Mammary Dog.
no.
1 2 3 4 5 6 7 8 9 10 11
Pulsatile
A orta Mean
Pulsatile
Mean
70 75 50 80 50 90 95 50 110 90
130/95 130/105 135/125 90/70 135/115 95/70 150/130 160/125 115/95 130/120 150/95
80 125 85 140 140 110 120 120
80/70 80/75 55/50 85/75
100/90 110/105 95/85
Table II. Retrograde flow from internal mammary artery Mean pressure {mm. Hg) 50 80 50 90 95 50
Flow (ml./min.)
7 13 20 36 34 14 24 36
State of
vessel
Patent Thrombosed Patent Thrombosed Thrombosed Patent Thrombosed Patent
Postmortem
angiogram
Coronary veins filled No intramyocardial vessels No intramyocardial vessels Coronary arteries filled via implant
Retrograde Transplant
Fig. 1. Diagram shows internal mammary artery implanted in tunnel deep to marginal branch of circumflex artery. Ameroid constrictor on circumflex artery is shown; a second one is placed on the right coronary artery.
557
5 5 8
Blesovsky
et al.
ments. One or two mediastinal branches were left bleeding and the terminal 2 to 2.5 cm. was implanted in a tunnel deep to the marginal branch of the circumflex artery (Fig. 1 ) . Angiograms were performed 3 to 7 months after operation: 75 per cent H y p a q u e solution was injected under pressure and films were taken on a SanchezPerez machine at two frames a second. The dogs were sacrificed and the implanted vessel was injected with a barium solution (Baridol).
Fig. 2. Injection of implanted mammary artery shows patency of vessel outside the heart, but no filling of intramyocardial vessels.
Table I I I . Retrograde coronary arteries)
implants (Ameroid
Status
Fig. 3. Injection of implanted vessel filled the coronary veins.
Fig. 4. Angiogram with opacification of mammary artery after retrograde implantation into the posterior myocardium. Note rapid disappearance of dye from anterior descending branch of left coronary artery and persistence of dye in implanted vessel 3 seconds later.
constrictors
A ngiogram (antemortem)
No.
Duration
5
3 wk.
Died
6
2 mo. 4 mo. 5 mo.
Sacrificed Sacrificed Sacrificed
Nonfilling Nonfilling
5 mo.
Sacrificed
Patent
5Vi mo. 7 mo.
Sacrificed Sacrificed
Patent Patent
to right and
circumflex
A ngiogram (postmortem) No intramyocardial vessels No intramyocardial vessels No intramyocardial vessels Veins filled Coronary arteries filled
Postmortem
findings
4 Thrombosed 1 Patent Thrombosed Thrombosed Patent Patent Minute lumen to vessel Lumen less than 1 mm.
Volume 53 Number 4
Retrograde internal mammary artery implantation
559
April, 1967
Results (Table III) Five dogs died within 3 weeks. In 4 of these the retrograde implant was thrombosed; in 1 it was patent to the myocardium but intramyocardial collaterals could not be demonstrated (Fig. 2). One dog lived for 2 months and was sacrificed because of severe heart failure; the implanted vessel was thrombosed. Five dogs lived longer than 3 months and each had antemortem angiograms made. The retrograde implant was opacified in 3
of these. In 1, the vessel was very thin and flow through it was slow; the anterior descending branch of the left coronary artery opacified on one frame, the implanted vessel remained opacified for six frames. At postmortem examination, the implanted vessel between the chest wall and myocardium was so narrowed that its lumen could not be cannulated. In the myocardial tunnel, the lumen was wider and a fine tube was introduced. The barium injection under high pressure outlined coronary veins (Fig. 3).
Fig. 5. Filling of coronary arteries by injection of implanted mammary vessel.
Journal of
5 6 0 Blesovsky et al.
In the second animal, the vessel opacified poorly. Intramyocardial collaterals could not be demonstrated by the Baridol injection. The third dog was the only one in which an intercoronary circulation was demonstrable. The vessel was patent by angiography at 3 and 7 months (Fig. 4 ) . The circulation through it was slow, however, opacifying for 5 seconds compared to 2 seconds for the anterior descending coronary artery. At postmortem the coronary arteries were filled from the implant (Fig. 5 ) . Of the 2 remaining animals that survived longer than 3 months, in which the retrograde implant did not opacify on angiocardiography, one implant was thrombosed and the other was patent but intramyocardial vessels were not demonstrated by the injection technique. Discussion It has been estimated that about 20 million patients in the United States could benefit from a successful procedure to revascularize an ischemic posterior myocardium.' Anatomically the internal mammary artery was easily implantable into the posterior myocardium by the retrograde technique. A retrograde pressure of two thirds of the aortic pressure was present, but the flow from the retrograde implant was disappointingly low. The results of this method in our hands have been poor. Of the 5 dogs in which the vessel remained patent as far as the myocardium, in only 1 were collateral connections to the coronary arteries present. The blood flow into the proximally transected mammary artery is via collaterals from the contralateral mammary, the intercostal arteries, and from the superior epigastric artery. The poor results in these experiments indicate that the collateral flow gives a circulation inadequate for the myocardium. These results are in striking contrast to the high rate of success of direct antegrade internal mammary implantations.3 The number of experiments in this series
Thoracic and Cardiovascular Surgery
Fig. 6. Injection study demonstrates patency of implanted vessel but absence of intramyocardial collaterals.
was small but was deliberately limited because the pressures and flows and patency rates obtained were poor when compared to the results obtained by other methods of myocardial revascularization being evaluated in this unit.'"7 Summary The retrograde implantation of the left internal mammary artery into the posterior myocardium was anatomically possible, the necessary length being obtained without tension. Our results indicate that for successful revascularization a higher pressure and flow are needed in the implanted vessel than were obtainable by this method. REFERENCES 1 Sones, F . J., Jr., and Shirey, E. K.: Cine Coronary Angiography, Mod. Concepts Cardiov. Dis. 3 1 : 735, 1962. 2 Effler, D. B„ Jones, F. M., Jr., Groves, K. L., and Suarez, E.: Increased Myocardial Perfusion by Internal Mammary Artery Implant, Ann. Surg. 158: 526, 1963. 3 Vineberg, A. M.: Development of Anastomosis Between Coronary Vessels and Transplanted Internal Mammary Artery, Canad. M. A. J. 55: 117, 1946. 4 Sones, F . M., Jr.: Discussion of Myocardial Revascularization,
J.
SURG. 50: 532, 1965.
THORACIC
&
CARDIOVAS.
Volume 53
Number 4
Retrograde internal mammary artery implantation
April, 1967
5 Kerth, W. J., Carapistolis, E. G., Sanchez, P. A., and Arguero, R.: Revascularization of the Posterior Myocardium With the Lengthened Internal Mammary Artery. In preparation. 6 Discussion of Pearce, Hyman, Brewer, Smith, and Creech: Myocardial Revascularization: Im-
561
plantation of Intercostal Artery, J. THORACIC & CARDIOVAS. SURG. 52: 809,
1966.
7 Blesovsky, A., Deal, C , Kerth, W. J., and Gerbode, F.: Revascularization of the Posterior Myocardium With a "Transplanted" Internal Mammary Artery. In preparation.
A renewed interest in revascularization of the heart has been stimulated by the development of coronary cineangiography1 and the angiographic demonstration of the high incidence of patency of the internal mammary artery after implantation into the heart.- Since the successful revascularization of the anterior part of the left ventricle, attention has been directed to the posterior myocardium to which the Vineberg procedure is not applicable.3 Many methods to revascularize this part of the heart are being tried in experimental From the Department of Cardiovascular Surgery, Presbyterian Medical Center, and the Institute of Medical Sciences, San Francisco, Calif. Aided in part by grants from U. S. Public Health Service, HE 5.149 and HE 06311. Received for publication Sept. 12, 1966. *Fellow, Department of Cardiovascular Surgery, Presbyterian Medical Center, and Department of Surgery, Stanford University School of Medicine, Palo Alto, Calif. Evarts A. Graham Travelling Fellow for 19651966 (sponsored by the American Association for Thoracic Surgery), and holder of a travelling grant from The Wellcome Trust, London, England. **Fellow, Department of Cardiovascular Surgery, Presbyterian Medical Center, and the Institute of Medical Sciences, San Francisco, Calif., and the Department of Surgery, Stanford University School of Medicine, Palo Alto, Calif., and Bay Area Heart Research Award. ***Director of Surgical Laboratory and Associate of Department of Cardiovascular Surgery, Presbyterian Medical Center, and the Institute of Medical Sciences, San Francisco, Calif. ****Chief of Cardiovascular Surgery, Presbyterian Medical Center, and the Institute of Medical Sciences, San Francisco, Calif., and Clinical Professor of Surgery, Stanford University School of Medicine, Palo Alto, Calif.
556
M.D.***
and clinical trials. We wish to report the results of experimental retrograde implantation of the internal thoracic (mammary) artery in a series of 11 dogs. This method was evaluated because of the accessibility of the vessel. Method Ameroid constrictors were placed on the right coronary and the circumflex branch of the left coronary arteries. The left internal mammary artery was freed by ligation or coagulation of side branches from its origin to the level of the fifth rib. It was transected proximally after ligation at its origin from the subclavian artery. In some dogs, simultaneous pressures were recorded in the distal part of the artery immediately after ligation and in the aorta (Table I ) . The mean pressure in the internal mammary averaged two thirds that in the aorta—the pulse pressure did not exceed 10 mm. Hg, and often the flow was not pulsatile. In a few dogs the vessel was allowed to bleed into a flask for 1 minute and the flow was measured (Table II). Flow was uniformly low when compared with flows of 160 to 200 ml. per minute from the distal end of an internal mammary artery freed of its intercostal branches from the second to the sixth intercostal spaces. The divided end of the vessel was ligated after taking pressure and flow measure-
Volume 53 Number 4 April, 1967
Retrograde internal mammary artery implantation
Table I. Retrograde mammary implant pressures (mm. Hg) Mammary Dog.
no.
1 2 3 4 5 6 7 8 9 10 11
Pulsatile
A orta Mean
Pulsatile
Mean
70 75 50 80 50 90 95 50 110 90
130/95 130/105 135/125 90/70 135/115 95/70 150/130 160/125 115/95 130/120 150/95
80 125 85 140 140 110 120 120
80/70 80/75 55/50 85/75
100/90 110/105 95/85
Table II. Retrograde flow from internal mammary artery Mean pressure {mm. Hg) 50 80 50 90 95 50
Flow (ml./min.)
7 13 20 36 34 14 24 36
State of
vessel
Patent Thrombosed Patent Thrombosed Thrombosed Patent Thrombosed Patent
Postmortem
angiogram
Coronary veins filled No intramyocardial vessels No intramyocardial vessels Coronary arteries filled via implant
Retrograde Transplant
Fig. 1. Diagram shows internal mammary artery implanted in tunnel deep to marginal branch of circumflex artery. Ameroid constrictor on circumflex artery is shown; a second one is placed on the right coronary artery.
557
5 5 8
Blesovsky
et al.
ments. One or two mediastinal branches were left bleeding and the terminal 2 to 2.5 cm. was implanted in a tunnel deep to the marginal branch of the circumflex artery (Fig. 1 ) . Angiograms were performed 3 to 7 months after operation: 75 per cent H y p a q u e solution was injected under pressure and films were taken on a SanchezPerez machine at two frames a second. The dogs were sacrificed and the implanted vessel was injected with a barium solution (Baridol).
Fig. 2. Injection of implanted mammary artery shows patency of vessel outside the heart, but no filling of intramyocardial vessels.
Table I I I . Retrograde coronary arteries)
implants (Ameroid
Status
Fig. 3. Injection of implanted vessel filled the coronary veins.
Fig. 4. Angiogram with opacification of mammary artery after retrograde implantation into the posterior myocardium. Note rapid disappearance of dye from anterior descending branch of left coronary artery and persistence of dye in implanted vessel 3 seconds later.
constrictors
A ngiogram (antemortem)
No.
Duration
5
3 wk.
Died
6
2 mo. 4 mo. 5 mo.
Sacrificed Sacrificed Sacrificed
Nonfilling Nonfilling
5 mo.
Sacrificed
Patent
5Vi mo. 7 mo.
Sacrificed Sacrificed
Patent Patent
to right and
circumflex
A ngiogram (postmortem) No intramyocardial vessels No intramyocardial vessels No intramyocardial vessels Veins filled Coronary arteries filled
Postmortem
findings
4 Thrombosed 1 Patent Thrombosed Thrombosed Patent Patent Minute lumen to vessel Lumen less than 1 mm.
Volume 53 Number 4
Retrograde internal mammary artery implantation
559
April, 1967
Results (Table III) Five dogs died within 3 weeks. In 4 of these the retrograde implant was thrombosed; in 1 it was patent to the myocardium but intramyocardial collaterals could not be demonstrated (Fig. 2). One dog lived for 2 months and was sacrificed because of severe heart failure; the implanted vessel was thrombosed. Five dogs lived longer than 3 months and each had antemortem angiograms made. The retrograde implant was opacified in 3
of these. In 1, the vessel was very thin and flow through it was slow; the anterior descending branch of the left coronary artery opacified on one frame, the implanted vessel remained opacified for six frames. At postmortem examination, the implanted vessel between the chest wall and myocardium was so narrowed that its lumen could not be cannulated. In the myocardial tunnel, the lumen was wider and a fine tube was introduced. The barium injection under high pressure outlined coronary veins (Fig. 3).
Fig. 5. Filling of coronary arteries by injection of implanted mammary vessel.
Journal of
5 6 0 Blesovsky et al.
In the second animal, the vessel opacified poorly. Intramyocardial collaterals could not be demonstrated by the Baridol injection. The third dog was the only one in which an intercoronary circulation was demonstrable. The vessel was patent by angiography at 3 and 7 months (Fig. 4 ) . The circulation through it was slow, however, opacifying for 5 seconds compared to 2 seconds for the anterior descending coronary artery. At postmortem the coronary arteries were filled from the implant (Fig. 5 ) . Of the 2 remaining animals that survived longer than 3 months, in which the retrograde implant did not opacify on angiocardiography, one implant was thrombosed and the other was patent but intramyocardial vessels were not demonstrated by the injection technique. Discussion It has been estimated that about 20 million patients in the United States could benefit from a successful procedure to revascularize an ischemic posterior myocardium.' Anatomically the internal mammary artery was easily implantable into the posterior myocardium by the retrograde technique. A retrograde pressure of two thirds of the aortic pressure was present, but the flow from the retrograde implant was disappointingly low. The results of this method in our hands have been poor. Of the 5 dogs in which the vessel remained patent as far as the myocardium, in only 1 were collateral connections to the coronary arteries present. The blood flow into the proximally transected mammary artery is via collaterals from the contralateral mammary, the intercostal arteries, and from the superior epigastric artery. The poor results in these experiments indicate that the collateral flow gives a circulation inadequate for the myocardium. These results are in striking contrast to the high rate of success of direct antegrade internal mammary implantations.3 The number of experiments in this series
Thoracic and Cardiovascular Surgery
Fig. 6. Injection study demonstrates patency of implanted vessel but absence of intramyocardial collaterals.
was small but was deliberately limited because the pressures and flows and patency rates obtained were poor when compared to the results obtained by other methods of myocardial revascularization being evaluated in this unit.'"7 Summary The retrograde implantation of the left internal mammary artery into the posterior myocardium was anatomically possible, the necessary length being obtained without tension. Our results indicate that for successful revascularization a higher pressure and flow are needed in the implanted vessel than were obtainable by this method. REFERENCES 1 Sones, F . J., Jr., and Shirey, E. K.: Cine Coronary Angiography, Mod. Concepts Cardiov. Dis. 3 1 : 735, 1962. 2 Effler, D. B„ Jones, F. M., Jr., Groves, K. L., and Suarez, E.: Increased Myocardial Perfusion by Internal Mammary Artery Implant, Ann. Surg. 158: 526, 1963. 3 Vineberg, A. M.: Development of Anastomosis Between Coronary Vessels and Transplanted Internal Mammary Artery, Canad. M. A. J. 55: 117, 1946. 4 Sones, F . M., Jr.: Discussion of Myocardial Revascularization,
J.
SURG. 50: 532, 1965.
THORACIC
&
CARDIOVAS.
Volume 53
Number 4
Retrograde internal mammary artery implantation
April, 1967
5 Kerth, W. J., Carapistolis, E. G., Sanchez, P. A., and Arguero, R.: Revascularization of the Posterior Myocardium With the Lengthened Internal Mammary Artery. In preparation. 6 Discussion of Pearce, Hyman, Brewer, Smith, and Creech: Myocardial Revascularization: Im-
561
plantation of Intercostal Artery, J. THORACIC & CARDIOVAS. SURG. 52: 809,
1966.
7 Blesovsky, A., Deal, C , Kerth, W. J., and Gerbode, F.: Revascularization of the Posterior Myocardium With a "Transplanted" Internal Mammary Artery. In preparation.