Rahimtoola, Shahbudin H.

A total of 696 patients with atrial septal defect (ASD) of either the secundum (90.5%) or the sinus venosus (9.5%) type were operated on at the Mayo Clinic from 1954 through 1965. Pulmonary hypertension (PHT, defined as pulmonary artery systolic pressure of 60 mm Hg or greater) or chronic congestive cardiac failure (CCF) (or both) was associated with 80% of the hospital deaths. For the years 1958 through 1965 (531 cases), the hospital mortality for these three groups was 10% (three of 30), 14% (one of seven), and 18% (two of 11), respectively; only two (0.4%) of the remaining 483 patients died, and both were more than 45 years old (among a total of 93 patients more than 45 years old). There have been no operative deaths among those less than 45 years of age and without PHT or CCF (390 cases) in the years 1958 through 1965. No operative deaths occurred in the years 1963 through 1965. Of 16 patients 60 years or older (1954 through 1965), one has died. A 6- to 12-year follow-up was possible on 397 patients operated on from 1954 through 1960. In the absence of PHT or CCF, 330 survived operation. Among the 53 patients more than 45 years old, four died later (not definitely related to closure of ASD), three were not well, 32 were in excellent health, and 14 were lost to follow-up in 1966. Among the 277 patients less than 45 years old, 10 died later (all but one probably unrelated to closure of ASD), three were unwell, 186 were in excellent health, and 78 were lost to follow-up in 1966. Forty-two patients with PHT survived operation in the period from 1954 through 1960. Ten had pulmonary resistance of more than 640 dynes sec cm -5 ; four of these were well, two had died (with PHT), two had severe PHT, one was in CCF, and one was moderately disabled. Thirty-two had pulmonary resistances of 640 dynes sec cm -5 or less; three of these had died (unrelated to closure of ASD), five were moderately disabled, 16 were in excellent health, and eight were lost to follow-up in 1966. Eighteen patients with CCF survived operation in the period from 1954 through 1960. All had had grade IV disability (New York Heart Association classification). There were three late deaths (one due to severe pulmonary vascular disease and two unrelated to closure of ASD), one patient had grade IV disability, five had grades I to II disability, eight were in excellent health, and one was lost to follow-up in 1966. Paroxysmal arrhythmia occurred in 75 of 397 patients (19%) operated on from 1954 through 1960. In 53 patients it was present preoperatively and persisted postoperatively in 15 of them (28%); in an additional 22 it appeared for the first time after closure of the ASD.

The ratio of the mean systolic transaortic valvular gradient to the mean systolic left ventricular pressure times 100 yields a percentage that represents the portion of left ventricular pressure-volume work per stroke lost because of outflow-tract obstruction. The percentage of the left ventricular stroke work loss and the area of the aortic orifice have been estimated in 49 patients with aortic valvular stenosis and two open-chest dogs with varying degrees of supravalvular aortic constriction. Left ventricular stroke work loss of 30% or greater was associated with calculated aortic valve areas of 1.0 cm 2 (or 0.60 cm 2 /m 2 ) or less. These values are representative of serious obstruction to left ventricular outflow, that is, approximately 75% or greater reduction of normal orifice size. The calculation of the percentage of left ventricular stroke work loss, besides being simple, is based upon the most reliable measurements obtainable at left heart catheterization, that of the pressure pulses.

Ventricular performance was assessed before and after angiocardiography in 22 patients with normal left ventricle, mitral stenosis, aortic stenosis, and myocardial disease. The increased circulating blood volume known to occur after angiocardiography is a determinant of the increased ventricular pre-load. The after-load is unchanged. Patients with normal left ventricle and some patients with valve stenosis responded by an increase in the work performed and some had only a minimal or no increase. A group of patients with serious heart disease performed less work. If the ventricular response can be considered on the basis of the Frank-Starling principle, then the abnormal response of such patients is due to an altered length-tension relationship.

Data from 43 patients with common ventricle for whom satisfactory hemodynamic data are available are presented; these form 3.2% of the patients with congenital heart disease studied by means of catheterization at the Mayo Clinic. Selective biplane angiocardiography is essential for diagnosis of common ventricle. Associated cardiovascular anomalies are common, with transposition of the great vessels occurring in 84% of the patients. The right-to-left shunt present in all 43 patients results in desaturation of systemic arterial blood. The common ventricle receives all the systemic and pulmonary venous blood [see table in the PDF file] flows; yet complete mixing is uncommon in this chamber, for it occurred in only 16% of the patients who did not have severe pulmonary stenosis. Fifty-eight per cent had oxygenated blood directed preferentially to the systemic circuit ("favorable streaming"). This occurred most commonly with L-transposition and resulted in a higher oxygen saturation of systemic arterial blood. Obstruction to pulmonary flow (from pulmonary stenosis or pulmonary vascular disease) results in a larger right-to-left shunt and lower oxygen saturation of systemic arterial blood.

Introduction of a cardiac catheter into the pulmonary artery from the right heart is not possible in a substantial proportion of patients with transposition of the great vessels. It is necessary to obtain the pulmonary artery pressure and oxygen saturation value to evaluate the degree of pulmonary stenosis and the pulmonary vascular resistance. Twenty-three patients are described in whom this was accomplished by percutaneous suprasternal puncture. There was no mortality and there were no significant complications. The technique appears to be safe and reliable.

Measurements of flow and pressures related to the left heart were made on 21 patients immediately prior to and at intervals of 2 and 4 minutes after angiocardiography. These patients had normal mitral valves (group 1), mitral incompetence (group 2), or mitral stenosis (group 3). There was an increase in left ventricular end-diastolic pressure accompanied by an increase in "pulmonary artery wedge" (PA wedge) pressure in all patients. Patients with mitral valve disease generally develop higher PA wedge pressures; those with mitral stenosis develop, in addition, significantly increased mean diastolic and end-diastolic gradients across the mitral valve. These increased gradients in mitral stenosis are due to increased flow across the mitral valve, which results from a combination of increased cardiac output and decreased diastolic filling time. Diagnostic angiocardiography affords an opportunity of observing the effects of valve lesions at a higher flow rate and is particularly useful in those patients with normal PA wedge pressure and small gradients initially.

Cardiac output was determined by the indicator-dilution technic with injection of indicator into the ascending aorta, left ventricle, and pulmonary artery in 13 cases of mitral incompetence and in 15 control cases (normal or mild valvular obstruction). The ascending aortic dye curve is not involved in mitral incompetence in its primary circulation and was used for comparison. In normal subjects, there is no significant difference between the cardiac output obtained by injection of indicator into the ascending aorta and the left ventricle. The cardiac output obtained from indicator-dilution curves affected by mitral regurgitation in its primary circulation is underestimated by approximately 20 per cent. The effects of the coronary recirculated indicator particles on the disappearance slope would best explain the discrepancy. Even in the normal circulation, the inclusion of the coronary recirculated particles leads to a small underestimation of the cardiac output when the indicator is injected into the pulmonary artery.

The cardiovascular response to angiographic contrast medium was studied in 28 patients undergoing diagnostic angiocardiography under anesthesia. A transient phase of hypotension and tachycardia similar to that described by other authors was noted. Cardiac output was increased initially by 50 per cent and returned to the base line in 20 minutes. Peripheral blood flow increased by 100 per cent, apparently due to the direct effect of the hyperosmotic solution on the vascular smooth muscle. Hemodilution, maximal 2 to 4 minutes after injection of contrast medium, suggested a transient increase in circulating blood volume. Increased ventricular filling pressures, which were thought to be due to hypervolemia, were associated with increased left ventricular stroke work.