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Aortic Insufficiency
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Aortic Insufficiency F. HENRY ELLIS, JR. JOHN W. KIRKLIN
THE use of plastic materials in cardiovascular surgery has received considerable impetus in recent years, and their use has made it possible to attack surgically another form of acquired cardiac disease, namely aortic insufficiency. Efforts to replace or reconstruct damaged cardiac valves by transplanted tissues, such as fascia, segments of pericardium, veins or arteries, have not met with uniform success. The experimental work of Hufnagel, leading to the development and clinical use of a plastic valve to counteract some of the deleterious physiologic effects of free aortic insufficiency, has been a noteworthy achievement. DEFINITION
Aortic insufficiency is a condition in which the aortic valves fail to close completely during diastole, with a resultant regurgitation of blood into the left' ventricle during this period of the cardiac cycle. It may be the result of syphilis, rheumatic fever, bacterial endocarditis or rarely, trauma. The impression existed formerly that aortic insufficiency as a relatively pure lesion was uncommon in rheumatic fever. It is becoming more and more apparent that rheumatic fever is responsible for a significant number of cases of aortic insufficiency. Fusion of the aortic cusps occurs in this disease, resulting in a deformed valve that may fail to close during diastole. Varying degrees of stenosis of the valvular orifice may accompany aortic insufficiency due to rheumatic fever. Interference with the normal function of the aortic valve occurs in about a third of all cases of syphilitic aortitis. The leaflets of the valve become cicatrized and incompetent as a result of inflammatory changes in the underlying aortic wall. Primary syphilitic valvulitis probably does not occur. The lateral parts of the aortic cusps coalesce with the aortic wall, leading to separation of the commissures. Dilatation of the aortic ring is usually present also, adding to the incompetency of the valve. Syphilitic involvement of the ostia of the coronary arteries is another accompaniment of syphilitic cardiovascular disease. 1035
1036
F. Henry Ellis, Jr., John W. Kirklin PATHOLOGIC PHYSIOLOGY
As a consequence of failure of the aortic valve to close properly, blood regurgitates into the left ventricle during diastole. The regurgitant stream may amount to 50 per cent of the volume of blood ejected from the left ventricle during systole. This volume, added to the volume of blood entering the left ventricle from the left atrium, produces initial ventricular volumes and tensions that are greater than normal, leading to a stronger systolic contraction and a larger systolic discharge. The stroke volume may be as much as twice the normal amount in order to maintain a normal rate of circulation. This added load on the left ventricle leads to left ventricular hypertrophy. It becomes increasingly difficult for the left ventricle to maintain an adequate cardiac output in the face of the reflux of large volumes of blood. Dilatation of the left ventricle follows, and this chamber may attain huge proportions in this disease. A relative mitral stenosis may occur, the result possibly of partial closure of the mitral valve due to the regurgitant aortic stream. When this occurs, the so-called Austin Flint murmur is produced. Dilatation of the mitral valvular ring and mitral insufficiency occur as left ventricular dilatation progresses. The ultimate result is increased pressure in the pulmonary trunk, with strain and eventual failure of the right side of the heart. The contour of the pressure pulse in aortic insufficiency differs significantly from normal (see Fig. 254, a, page 921). The greater force of systolic ejection and the lessened aortic diastolic pressure allow a more rapid, earlier and more nearly complete ejection of blood from the left ventricle than are present normally. The rise in the ascending limb of the aortic pressure pulse is sharper than normal. There is pronounced amplification of the systolic pulse in peripheral vessels. Because of the rapid initial systolic ejection, the pressure in the aorta decreases rapidly during the latter part of systole, producing an early decline in the peripheral pulse. A further decrease in pressure occurs during diastole as a result of regurgitation during this period of the cardiac cycle, leading to a diastolic pressure that is less than normal and an increased pulse pressure. DIAGNOSIS
Aortic insufficiency may give few symptoms until late in the course of the disease, at which time angina pectoris and congestive heart failure appear. Once symptoms occur, a rapidly downhill course ensues. Life is usually measured in months from the onset of symptoms in the syphilitic form of aortic insufficiency, despite good medical management. The outlook in patients who have aortic insufficiency due to rheumatic fever is somewhat better; however, failure, once it occurs, is difficult to control by medical means.
1037
A ortic Insufficiency
Examination discloses a blowing diastolic murmur in the third and fourth interspaces just to the left of the sternum. It is best heard during expiration with the patient erect or bent slightly forward. The murmur also may be heard at the apex but should not be confused with a mitral diastolic murmur, which is rumbling in quality and occurs later in the cardiac cycle. An associated diastolic murmur, the afore-mentioned Austin Flint murmur, may occur at the apex in the absence of mitral valvular disease. The heart is enlarged to the left. Extreme degrees of left ventricular enlargement may be seen in this condition. The pulse is collapsing (Corrigan) in nature, and there is a wide pulse pressure, with decreased diastolic and increased systolic pressures. Thoracic roentgenograms disclose a large heart that is increased in size in a downward direction to the left, with a rounded apex. The electrocardiogf!tm in uncomplicated cases reveals evidence of left ventricular hypertrophy. The contours obtained during studies of intra-arterial aortic and arterial pressure pulses may demonstrate features characteristic of aortic insufficiency. Brief reference to these features already has been made. INDICATIONS FOR OPERATION
Since the operation at present available for this disease does not result in complete physiologic cure, only those patients whose symptoms are severe and progressive are considered by us as candidates for operation. To date we have not denied the operation to any patient because of the severity of his cardiac failure. However, we frequently have advised against operation in patients who are doing reasonably well. It is apparent that the indications for operation will change should a more nearly perfect physiologic operation be available. TECHNIQUE OF OPERATION
The patient is placed in the right lateral decubitus position and the left side of the thorax is entered through the bed of the resected fifth rib. The aorta is mobilized from the origin of the left subclavian artery for a distance of 8 to 10 em., the intercostal vessels being carefully ligated and divided. A previously sterilized Hufnagel valve is selected to fit the patient's aorta. Two nylon rings with multiple points of fixation are used to anchor this valve; these rings, together with their attached ligatures, are passed around the intact aorta. A special valve holder designed by Dr. JD Mortensen is used to grasp the valve and fit it in place (Fig. 302). The aorta is occluded by use of Potts aortic clamps and is divided beyond the curve of the aortic arch, where the aorta is straight. A small segment of aorta is excised. The distal end of the divided aorta is grasped with Allis clamps and held open while the valve is inserted into the lumen. One of the previously placed nylon rings is placed over the groove in the valve and closed tightly by a ring-
1038
F. Henry Ellis, Jr., John W. Kirklin
holding clamp while the encircling ligature is tied snugly. The proximal end of the valve is inserted into the proximal part of the aorta and fixed in place in a similar manner by tying the ligature that encircles the other nylon ring. The ring clamp and valve holder are removed. A dilute solution of heparin is injected into the artificial valve and as much air as possible is removed. The distal aortic clamp is opened first and then the proximal one is removed. Both clamps are released slowly. The site at which the valve is inserted is:covered with a thin sheet of polyvinyl sponge (Ivalon). This not only.,helps to muffle the sound of the working valve but is added protection should the aortic wall be cut through by the nylon rings. The total time of aortic occlusion should not exceed 15 minutes; it averages from six to eight minutes. This is well within the time limit beyond which neurologic damage may occur from ischemia of the spinal cord. The use of hypothermia is not required.
Fig. 302. Mortensen valve holder grasping a Hufnagel valve. In foreground are the two nylon rings with multiple points of fixation. The encircling ligatures are in place. RESULTS OF OPERATION
It has been demonstrated experimentally that approximately 75 per cent of aortic reflux is controlled by placing the valve just distal to the left subclavian artery. Physiologic studies on patients on whom we have performed this operation show that about 66 per cent of the output of the left ventricle passes through the Hufnagel valve in the descending aorta. Only one death has occurred in the hospital in our small group of eight patients in whom the Hufnagel valve has been inserted. One death took place several months after the patient returned home. The remaining six patients appear to be improved symptomatically, although none has returned to completely normal activity. Our experience is too limited to allow an accurate evaluation of the operation. In spite of this, it is our belief at present that available evidence indicates that the operation is of value and is advisable in patients who have severe symptoms from aortic insufficiency. Like aortic stenosis,
--Aortic Insufficiency
1039
however, this is a disease for which a perfect operation is not available as yet. Further developments may allow performance of a more nearly perfect physiologic procedure; when this is available, surgical correction of aortic insufficiency will be indicated more often.
Aortic Insufficiency F. HENRY ELLIS, JR. JOHN W. KIRKLIN
THE use of plastic materials in cardiovascular surgery has received considerable impetus in recent years, and their use has made it possible to attack surgically another form of acquired cardiac disease, namely aortic insufficiency. Efforts to replace or reconstruct damaged cardiac valves by transplanted tissues, such as fascia, segments of pericardium, veins or arteries, have not met with uniform success. The experimental work of Hufnagel, leading to the development and clinical use of a plastic valve to counteract some of the deleterious physiologic effects of free aortic insufficiency, has been a noteworthy achievement. DEFINITION
Aortic insufficiency is a condition in which the aortic valves fail to close completely during diastole, with a resultant regurgitation of blood into the left' ventricle during this period of the cardiac cycle. It may be the result of syphilis, rheumatic fever, bacterial endocarditis or rarely, trauma. The impression existed formerly that aortic insufficiency as a relatively pure lesion was uncommon in rheumatic fever. It is becoming more and more apparent that rheumatic fever is responsible for a significant number of cases of aortic insufficiency. Fusion of the aortic cusps occurs in this disease, resulting in a deformed valve that may fail to close during diastole. Varying degrees of stenosis of the valvular orifice may accompany aortic insufficiency due to rheumatic fever. Interference with the normal function of the aortic valve occurs in about a third of all cases of syphilitic aortitis. The leaflets of the valve become cicatrized and incompetent as a result of inflammatory changes in the underlying aortic wall. Primary syphilitic valvulitis probably does not occur. The lateral parts of the aortic cusps coalesce with the aortic wall, leading to separation of the commissures. Dilatation of the aortic ring is usually present also, adding to the incompetency of the valve. Syphilitic involvement of the ostia of the coronary arteries is another accompaniment of syphilitic cardiovascular disease. 1035
1036
F. Henry Ellis, Jr., John W. Kirklin PATHOLOGIC PHYSIOLOGY
As a consequence of failure of the aortic valve to close properly, blood regurgitates into the left ventricle during diastole. The regurgitant stream may amount to 50 per cent of the volume of blood ejected from the left ventricle during systole. This volume, added to the volume of blood entering the left ventricle from the left atrium, produces initial ventricular volumes and tensions that are greater than normal, leading to a stronger systolic contraction and a larger systolic discharge. The stroke volume may be as much as twice the normal amount in order to maintain a normal rate of circulation. This added load on the left ventricle leads to left ventricular hypertrophy. It becomes increasingly difficult for the left ventricle to maintain an adequate cardiac output in the face of the reflux of large volumes of blood. Dilatation of the left ventricle follows, and this chamber may attain huge proportions in this disease. A relative mitral stenosis may occur, the result possibly of partial closure of the mitral valve due to the regurgitant aortic stream. When this occurs, the so-called Austin Flint murmur is produced. Dilatation of the mitral valvular ring and mitral insufficiency occur as left ventricular dilatation progresses. The ultimate result is increased pressure in the pulmonary trunk, with strain and eventual failure of the right side of the heart. The contour of the pressure pulse in aortic insufficiency differs significantly from normal (see Fig. 254, a, page 921). The greater force of systolic ejection and the lessened aortic diastolic pressure allow a more rapid, earlier and more nearly complete ejection of blood from the left ventricle than are present normally. The rise in the ascending limb of the aortic pressure pulse is sharper than normal. There is pronounced amplification of the systolic pulse in peripheral vessels. Because of the rapid initial systolic ejection, the pressure in the aorta decreases rapidly during the latter part of systole, producing an early decline in the peripheral pulse. A further decrease in pressure occurs during diastole as a result of regurgitation during this period of the cardiac cycle, leading to a diastolic pressure that is less than normal and an increased pulse pressure. DIAGNOSIS
Aortic insufficiency may give few symptoms until late in the course of the disease, at which time angina pectoris and congestive heart failure appear. Once symptoms occur, a rapidly downhill course ensues. Life is usually measured in months from the onset of symptoms in the syphilitic form of aortic insufficiency, despite good medical management. The outlook in patients who have aortic insufficiency due to rheumatic fever is somewhat better; however, failure, once it occurs, is difficult to control by medical means.
1037
A ortic Insufficiency
Examination discloses a blowing diastolic murmur in the third and fourth interspaces just to the left of the sternum. It is best heard during expiration with the patient erect or bent slightly forward. The murmur also may be heard at the apex but should not be confused with a mitral diastolic murmur, which is rumbling in quality and occurs later in the cardiac cycle. An associated diastolic murmur, the afore-mentioned Austin Flint murmur, may occur at the apex in the absence of mitral valvular disease. The heart is enlarged to the left. Extreme degrees of left ventricular enlargement may be seen in this condition. The pulse is collapsing (Corrigan) in nature, and there is a wide pulse pressure, with decreased diastolic and increased systolic pressures. Thoracic roentgenograms disclose a large heart that is increased in size in a downward direction to the left, with a rounded apex. The electrocardiogf!tm in uncomplicated cases reveals evidence of left ventricular hypertrophy. The contours obtained during studies of intra-arterial aortic and arterial pressure pulses may demonstrate features characteristic of aortic insufficiency. Brief reference to these features already has been made. INDICATIONS FOR OPERATION
Since the operation at present available for this disease does not result in complete physiologic cure, only those patients whose symptoms are severe and progressive are considered by us as candidates for operation. To date we have not denied the operation to any patient because of the severity of his cardiac failure. However, we frequently have advised against operation in patients who are doing reasonably well. It is apparent that the indications for operation will change should a more nearly perfect physiologic operation be available. TECHNIQUE OF OPERATION
The patient is placed in the right lateral decubitus position and the left side of the thorax is entered through the bed of the resected fifth rib. The aorta is mobilized from the origin of the left subclavian artery for a distance of 8 to 10 em., the intercostal vessels being carefully ligated and divided. A previously sterilized Hufnagel valve is selected to fit the patient's aorta. Two nylon rings with multiple points of fixation are used to anchor this valve; these rings, together with their attached ligatures, are passed around the intact aorta. A special valve holder designed by Dr. JD Mortensen is used to grasp the valve and fit it in place (Fig. 302). The aorta is occluded by use of Potts aortic clamps and is divided beyond the curve of the aortic arch, where the aorta is straight. A small segment of aorta is excised. The distal end of the divided aorta is grasped with Allis clamps and held open while the valve is inserted into the lumen. One of the previously placed nylon rings is placed over the groove in the valve and closed tightly by a ring-
1038
F. Henry Ellis, Jr., John W. Kirklin
holding clamp while the encircling ligature is tied snugly. The proximal end of the valve is inserted into the proximal part of the aorta and fixed in place in a similar manner by tying the ligature that encircles the other nylon ring. The ring clamp and valve holder are removed. A dilute solution of heparin is injected into the artificial valve and as much air as possible is removed. The distal aortic clamp is opened first and then the proximal one is removed. Both clamps are released slowly. The site at which the valve is inserted is:covered with a thin sheet of polyvinyl sponge (Ivalon). This not only.,helps to muffle the sound of the working valve but is added protection should the aortic wall be cut through by the nylon rings. The total time of aortic occlusion should not exceed 15 minutes; it averages from six to eight minutes. This is well within the time limit beyond which neurologic damage may occur from ischemia of the spinal cord. The use of hypothermia is not required.
Fig. 302. Mortensen valve holder grasping a Hufnagel valve. In foreground are the two nylon rings with multiple points of fixation. The encircling ligatures are in place. RESULTS OF OPERATION
It has been demonstrated experimentally that approximately 75 per cent of aortic reflux is controlled by placing the valve just distal to the left subclavian artery. Physiologic studies on patients on whom we have performed this operation show that about 66 per cent of the output of the left ventricle passes through the Hufnagel valve in the descending aorta. Only one death has occurred in the hospital in our small group of eight patients in whom the Hufnagel valve has been inserted. One death took place several months after the patient returned home. The remaining six patients appear to be improved symptomatically, although none has returned to completely normal activity. Our experience is too limited to allow an accurate evaluation of the operation. In spite of this, it is our belief at present that available evidence indicates that the operation is of value and is advisable in patients who have severe symptoms from aortic insufficiency. Like aortic stenosis,
--Aortic Insufficiency
1039
however, this is a disease for which a perfect operation is not available as yet. Further developments may allow performance of a more nearly perfect physiologic procedure; when this is available, surgical correction of aortic insufficiency will be indicated more often.