early assessment of hemodynamic status after repair of tetralogy of fallot: a comparison of 24 hour...

Early Assessment of Hemodynamic Status After Repair of Tetralogy of Fallot: A Comparison of 24 Hour (Intensive Care Unit) and 1 Year Postoperative Data in 98 Patients

PETER LANG, MD, CARL W. CHIPMAN, RN, HAROLD SIDEN,

ROBERTA G. WILLIAMS, MD, WILLIAM I. NORWOOD, MD, and ALDO R. CASTANEDA, MD

Hemodynamic data obtained in the intensive care unit, immediately after repair of tetralogy of Fallot, were compared with measurements obtained at 1 year postoperative catheterization in 98 Infants and children. Eight of 12 patients who had pulmonary artery oxygen saturation of 80% or greater in the intensive care unit had a pulmonary to systemic flow ratio greater than 1.5 at catheterization; all 79 patients who had a pulmonary artery oxygen saturation of less than 80% in the intensive care unit had a pulmonary to systemic flow ratio of 1.5 or less at catheterization. Five of six patients who had a right ventricular outflow tract pressure gradient greater than 40 mm Hg in the intensive care unit had a gradient greater than 40 mm Hg at catheterization; 7 of 81 patients who had a right ventricular outflow tract gradient of 40 mm Hg or less in the intensive

care unit had a gradient greater than 40 mm Hg at catheterization. The addition of measurements of right ventricular pressure and the right ventricular to systemic arterial pressure ratio in the intensive care unit did not improve sensitivity in identifying patients with a right ventricular outflow tract gradient greater than 40 mm Hg at catheterization.

Intensive care unit measurement of pulmonary artery oxygen saturation is valuable for determining the presence or absence of a significant left to right shunt after repair of tetralogy of Fallot and should be considered an adjunct to patient management. Intensive care unit measurement of the right ventricular outflow tract gradient identifies patients with a significant right ventricular outflow tract gradient at catheterization but is not highly sensitive.

The results of the present surgical treatment of tetralogy of Fallot have progressed to a point where operative mortality and morbidity are exceedingly low1r2; present concerns focus on the timing of surgery,3-5 variations in surgical technique,6 and late hemodynamic results.7,8 Patients who remain symptomatic after surgery often have identifiable persistent structural abnormalities.9

From the Departments of Cardiology and Cardiovascular Surgery, The Children’s Hospital Medical Center, and the Departments of Pediatrics and Surgery, Harvard Medical School, Boston, Massachusetts. This study was supported in part by Grant HL05624 from the National Heart, Lung, and Blood Institute. National Institutes of Health, Bethesda, Maryland. Manuscript received December 15, 1961; revised manuscript received February 17, 1962, accepted March 5, 1962.

Address for reprints: Peter Lang, MD, Department of Cardiology, Children’s Hospital Medical Center, 300 Longwood Avenue, Boston, Massachusetts 02 115.

It has been demonstrated that myocardial performance will be adversely affected by such defects.‘O The purpose of the present investigation was to determine whether patients with residual defects can be identified in the immediate postoperative period so that appropriate treatment can be undertaken without delay. Accord- ingly, hemodynamic data obtained in the early (24 hour) postoperative period are compared with those obtained i year after surgery. _

Postoperative assessment of hemodynamic status after repair of tetralogy of Fallot has been routine at this medical center since 1974. Catheters are placed in the left atrium, right atrium, pulmonary artery (through the right ventricular free wall), and a peripheral systemic artery at the time of surgery. Simultaneous determination of the oxygen saturation of blood samples obtained through these catheters allows determination of

October 1982 The American Journal of CARDIOLOGY Volume 50 795

HEMODYNAMICS AFTER TETRALOGY REPAIR-LANG ET AL

FIGURE 1. “Truth” tables relating immediate postoperative data to pulmonary to systemic flow ratio 1 year after surgery in all 98 patients. A, intensive care unit (CU) pulmonary arterial oxygen saturation (PAO$) of 80% or greater as predictive of 1 year postoperative catheterization (Cath) pulmonary to systemic flow ratio (Qp/Qs) greater than 1.5. 6, intensive care unit Qp/Qs greater than 1.5 as predictive of catherization Qp/Qs greater than 1.5. C, intensive care unit step-up in oxygen saturation from right atrium to pulmonary artery of 10% or greater as predictive of catheterization QplQs greater than 1.5.

Cath Qp/O,

=-IS 51.5

Sensitivity 100% Specificity 96% Frediiive Vahe 0 67% PredictiveValue 100%

a pulmonary to systemic flow ratio. A pressure recording of a pullback of the pulmonary artery catheter from the pulmonary artery across the right ventricular outflow tract to the right ventricle allows determination of obstruction at this level. These measurements are rou- tinely performed 24 hours after surgery. In addition, 1 year postoperative hemodynamic evaluation by cardiac catheterization is recommended to all patients who have undergone repair of tetralogy of Fallot.

ratio of 1.1. The right ventricular outflow tract gradient was determined by subtracting the peak distal pulmonary arterial systolic pressure from the peak right ventricular systolic pressure recorded during the same catheter pullback.

Analysis of data: “Truth” tables were constructed com- paring immediate postoperative data with those obtained at 1 year postoperative catheterization. Immediate postoperative data were compared with the pulmonary to systemic flow ratio and the right ventricular outflow tract gradient determined at cardiac catheterization.

Methods Results

Patients: The records of all patients who underwent repair of tetralogy of Fallot at Children’s Hospital Medical Center, Boston between January 1974 and June 1979 were examined. Of these, we studied 98 patients for whom data existed per- taining to intracardiac shunting or right ventricular outflow tract obstruction, or both, in the early postoperative period and at 1 year postoperative catheterization. Four patients with additional major intracardiac lesions and 25 who required an external conduit for right ventricular outflow tract reconstruction were excluded. In addition, there are 5 patients for whom no early postoperative data are available and 68 patients who have not undergone cardiac catheterization since surgery.

Residual left to right shunts: The immediate postoperative pulmonary to systemic flow ratio, the absolute step-up in oxygen saturation from the right atrium to the pulmonary artery, and the oxygen saturation in the pulmonary artery were compared with the pulmonary to systemic flow ratio at 1 year postoperative catheterization (Fig. 1 and 2). All 3 measurements were highly sensitive in identifying patients with a hemo- dynamically significant left to right shunt. More data were available for analysis with use of pulmonary arterial oxygen saturation alone because of malfunction of

Early postoperative studies: These were performed 18 to 36 hours after surgery. No patient was receiving supple- mental oxygen at a fractional inspired oxygen concentration greater than 0.5. Blood samples were drawn simultaneously from the right atrial, pulmonary arterial, left atrial, and systemic arterial catheters and oxygen saturation measurements were made. Pullback pressure tracings from the pulmonary artery to the right ventricle (or right ventricular pressure tracing alone if the catheter was in the right ventricle) were recorded. The right ventricular outflow tract pressure gradient was determined by subtracting the peak pulmonary artery systolic pressure from the peak right ventricular systolic pressure.

5.0

1 4.oL

One year follow-up studies: At cardiac catheterization, pulmonary to systemic flow ratios were determined by the Fick principle using pulmonary artery, superior vena cava, and systemic arterial oxygen saturations obtained during the rapid pullback of the catheter from pulmonary artery to superior vena cava while measuring oxygen consumption. If there was no step-up in oxygen saturation but left ventricular angiog- raphy revealed a tiny residual ventricular septal defect, the patient was arbitrarily assigned a pulmonary to systemic flow

8 3.0 _ \

& I 2.0_ 2 0

1.0 _

I I I I I a I

55 60 65 70 75 60 85 70

ICU PAO,S (%I

FIGURE 2. Relationship of pulmonary arterial oxygen saturation (PAO$S) in the immediate postoperative period in the intensive care unit (ICU) to the pulmonary to systemic flow ratio (Qp/Qs) at catheterization (Cath) 1 year after surgery in all patients.

0.

Cae QP/OS

>1.5 I 51.5

Sensitivity 66% Specificity 96% Predicti~WusO 67% !+edictive Value@ 96%

Cath QpXk

Smsitwity 661 Specificity 94% Predictive Value 0 60x Predictive Value 0 96%

.

796 October 1982 The American Journal of CARDIOLOGY Volume 50

HEMODYNAMICS AFTER TETRALOGY REPAIR--LANG ET AL.

A. Cath RVOTG

Sensltivlty 42a

Sfxaliclty 98:.

PrediitiveVabO 83‘.

P~edictiveValueO 89””

Cath RVOTG Cath RVQTG

Sermtiwty 50’ Semitwty 25

Specifiaty 93”. Specificity 95

RedictiveValwO 60 Predictive Wue 0 50 Prediitive l&he0 90”. Predictive Value0 86:

FIGURE 3. “Truth” tables relating immediate postoperative data to the right ventricular outflow tract gradient 1 year after surgery in all patients. A, intensive care unit (CU) right ventricular outflow tract gradient (RVOTG) greater than 40 mm Hg as predictive of 1 year postoperative catheterization (Cath) right ventricular outflow tract gradient greater than 40 mm Hg. B. intensive care unit right ventricular pressure (RV,,) greater than 60 mm Hg as predictive of catherization right ventricular outflow tract gradient greater than 40 mm Hg. C, intensive care unit right ventricular to systemic arterial pressure ratio (RV/Ao) greater than 0.65 as predictive of catheterization right ventricular outflow tract gradient greater than 40 mm Hg.

some of the right atria1 catheters. One patient had a right atria1 and pulmonary arterial oxygen saturation of 87% in the immediate postoperative period and a pulmonary to systemic flow ratio of 2.0 at catheterization and was identified as having a significant residual shunt only if the pulmonary artery oxygen saturation alone was evaluated. Table I presents the relevant intensive care unit and catheterization data on the 8 patients with a pulmonary to systemic flow ratio greater than 1.5 at catheterization. With the exception of the 1 patient mentioned (Case 6), all patients could be identified in the intensive care unit by either a pulmonary to systemic flow ratio greater than 1.5, a pulmonary arterial ox_vgen saturation of 80% or greater, or an increase in oxygen saturation of at least 10%.

Residual right ventricular outflow tract obstruction: The immediate postoperative right ventricular outflow tract gradient, the right ventricular

TABLE I Summary of Data on 8 Patients With a Significant Left to Right Shunt (QplQs Greater Than 1.5) at 1 Year Postoperative Catheterization (Cath)

.-_______ _______

ICU ICU 02 Cath PAO*S ICU Step-Up

Patient Qp/Qs (%) QplQs (%) ~___ _~____ 6 2.0 * 1.0 18 1.7 iI* 1.9’ 1:+

z; 3.3 *

::* 3.6’ 26‘

2.2 70 2.5 *

:z* 2:4; 2i;

;3” 1.6 2.1’ 15” 2.1 *

% 1.9’ I

96 4.4 2.0’ z* ___~ ~~_

ICU = intensive care unit; O2 Step-Up = step-up in oxygen saturation from right atrium to pulmonary artery; PAOPS = pulmonary arterial oxygen saturation: Qp/Qs = pulmonary to systemic flow ratio.

1. * Values predictive of residual left to right shunt as shown in Figure

pressure, and the right ventricular to systemic arterial pressure ratio were compared with the right ventricular outflow tract gradient at I year postoperative catheterization (Fig. 3 and 4). None of these variables was highly sensitive in identifying patients with significant late residual obstruction. Table II summarizes the pressure data on the 12 patients with a right ventricular outflow tract gradient greater than 40 mm Hg at follow-up catheterization. Only 6 of these patients had evidence of significant residual right ventricular outflow tract obstruction in the immediate postoperative period.

CATH RVOTG (mmHg)

.

100,

80 _

.

60_ . . l * .

20 40 60 80 100

ICU RVOTG (mmHg)

FIGURE 4. Relationship of the right ventricular outflow tract gradient in the immediate postoperative period (ICU RVOTG) to the right ventricular outflow tract gradient 1 year after surgery (CATH RVOTG) in all patients.


HEMODYNAMICS AFTER TETRALOGY REPAIR-LANG ET AL

Discussion confirmation of shunt size and localization of the defect by cardiac catheterization and left ventricular angiog- raphy. Patients shown to have a pulmonary to systemic flow ratio greater than 1.5 undergo closure of the residual defect. The importance of angiographic localization of residual defects was recently stressed by the demonstration that 14% of infants with tetralogy of Fallot have multiple or complicated ventricular septal defects. i2

Diagnosis of residual postoperative right ventricular obstruction: Our ability to identify patients in the immediate postoperative period who had significant residual right ventricular outflow tract obstruction demonstrated at 1 year postoperative catheterization was not striking. Measurement of the right ventricular outflow tract gradient in the intensive care unit identified only 5 of 12 patients, but with only 1 false-positive result. Measurement of right ventricular pressure or the right ventricular to systemic arterial pressure ratio did not identify significantly more patients but did have a higher rate of false-positive diagnoses. There are several possible explanations for the poor specificity of the measurements. Right ventricular outflow tract gradients measured in the intensive care unit would fail to identify patients with distal pulmonary arterial branch obstruction if the monitoring catheter were in the con- tralateral or main pulmonary artery. However, one would then expect an elevated right ventricular pressure. This was not always the case (Table II). The failure to observe an elevated right ventricular pressure as well as the low right ventricular outflow tract gradient measured in the intensive care unit in patients with significant obstruction 1 year later may indicate that right ventricular outflow tract, gradients increase with time. It is interesting to note that several centers’J employ intraoperative measurement of the right ventricular to systemic arterial pressure ratio as an index of the adequacy of right ventricular outflow tract reconstruction. Our data suggest that this may fail to

The principal aims of surgical repair of tetralogy of Fallot are the abolition of intracardiac shunting and the relief of right ventricular outflow tract and pulmonary arterial obstruction. Failure to adequately close an in- terventricular communication results in left to right shunting if the obstruction to pulmonary blood flow is relieved. The adverse effects of such a shunt after repair of tetralogy of Fallot have been dem0nstrated.l” Al- though the significance of mild to moderate persistent right ventricular outflow tract obstruction has not been clarified, recent evidence suggests that it contributes to ventricular arrhythmias, which in turn have been correlated with late sudden death.”

Diagnosis and management of residual postoperative left to right shunt: The detection of a significant left to right shunt in patients immediately after repair of tetralogy of Fallot is often difficult on clinical examination. Systolic and diastolic mumurs associated with reconstruction of the right ventricular outflow tract and some degree of congestive cardiac failure are almost universal in the early postoperative period. Noninvasive diagnostic techniques such as echocardiography and radionuclide angiocardiography lose specificity in the presence of pulmonary regurgitation. The persistence of congestive failure beyond several months indicates a likelihood of significant hemodynamic defects; earlier recognition followed by repair is possible.

The techniques employed in this study were highly sensitive in identifying patients shown to have a pulmonary to systemic flow ratio greater than 1.5 one year after surgery. All 8 patients with a significant shunt at 1 year postoperative catheterization had a pulmonary arterial oxygen saturation of 80% or greater in the intensive care unit. Such shunting can result from in- complete closure of the malalignment ventricular septal defect of tetralogy of Fallot or from the presence of additional defects. We currently recommend early

TABLE II Summary of Data on 12 Patients With a Significant Right Ventricular Outflow Tract Gradient (Greater Than 40 mm Hg) at 1 Year Postoperative Catheterization (Cath)

Patient

Cath Cath RVOTG RVP

(mm Hg) (mm t-fg)

ICU RVOTG

(mm t-fg)

ICU RVP

(mm Hg)

ICU RV/Ao Ratio

5 10 25 40

t”B 53 62 67 78 a2 96

iA 45 65 48 65 90 107 46’ 41 57 44’

70 46’ 100 14

40 28

t:

E* 52 80”

11

& 65’ 64’

0.41 0.28 0.41 0.43 0.34 0.86” 0.51 0.69’ 0.66’ 0.65’ 0.54 0.54

ICU = intensive care unit; RV/Ao = right ventricular to systemic arterial pressure ratio; RVOTG = right ventricular outflow tract gradient; RVP = right ventricular pressure.

l Values predictive of residual right ventricular outflow tract obstruction as shown in Figure 3.

798 October 1982 The American Journal of CARDIOLOGY Volume 50

HEMODYNAMICS AFTER TETRALOGY REPAIR-LANG ET AL.

identify significant residual obstruction. In addition, otherslZ3 have recently shown that such measurements may be misleadingly high.

Our current recommendations for hemodynamic evaluation of patients after repair of tetralogy of Fall& include (1) measurements of pulmonary arterial oxygen saturation and right ventricular outflow tract gradient in the intensive care unit after surgery, (2) early catheterization of patients with a pulmonary arterial oxygen saturation greater than 80% or a right ventricular outflow tract gradient greater than 40 mm Hg, and (3) catheterization of all patients 1 year after surgery.

1.

2.

3.

References

Poirier RA, McGoon DC, Danielson GK, et al. Late results after repair of tetralogy of Fallot. J Thorac Cardiovasc Surg 1977;73:900-908. Castaneda AR, Freed MD, Williams FIG, Norwood WI. Repair of tetralogy of Fallot in infancy. Early and late results. J Thorac Cardiovasc Surg 1977;74:372-381. Kirklin JW, Blackstone EH, Pacific0 AD, Brown RN, Bargeron LM. Routine primary vs two-stage repair of tetralogy of Fallot. Circulation 1979;60: 373-386.

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Murphy JD, Freed MD, Keane JF, Norwood WI, Caslaneda AR, Nadas AS. Hemodynamic results after intracardiac repair of tetralogy of Fallot by deep hypothermia and cardiopulmonary bypass. Circulation 1980;62: Suppl I: I-168-174 Borow K. Green LH. Castaneda AR. Keane JF. Left ventricular function after repair of tetralogy of Fallot and’its relationship to age at repair. Cir- culation 1960;61:1150-1158. Calder AL, Barratt-Boyes BG, Brandt PWT, Neutze JM. Postoperative evaluation of oatients with tetraloav of Fallot reoaired in infancv. J Thorac Cardiovasc S&g 1979;77:704-7%.

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Sunderland CO, Matarazzo RG, Lees MH, et al. Total correction of tetralogy of Fallot in infancy. Postoperative hemodynamic evaluation. Circulation 1973;48:398-405. Ruzyllo W, Nihill MR, Mullins CE, McNamara DG. Hemodynamic evaluation of 22 1 patients after intracardiac repair of tetralogy of F&lot. Am J Cardiol 1974:34:565-576. Rocchini AP, Rosenthal A, Freed M, Castaneda AR. Nadas AS. Chronic congestive heart failure after repair of tetralogy of Fallot. Circulation 1977:56:305-310. Rocchini AP, Keane JF, Freed MD, Castaneda AR, Nadas AS. Left ventricular function following attempted surgical repair of tetralogy of Fallot. Circulation i978;57:798-802. Garson A, Gillette PC, Gutgesell HP, McNamara DG. Stress-induced ventricular arrhythmia after repair of tetralogy of Fallot. Am J Cardiol 1960;46:1006-1012. Fellows KE, Smith J, Keane JF. Preoperative angiocardiography of infants with tetrad of Fallot. Am J Cardiol 1961;47:1279-1285. Goor DA, Smolinsky A, Mohr R, Caspi J, Shem-Tov A. The 24 hour drop of residual right ventricular pressure after conservative infundibulectomy in repalr of tetralogy of Fallot. J Thorac Cardiovasc Surg 1981;61:697- 909.


early assessment of hemodynamic status after repair of tetralogy of fallot: a comparison of 24 hour...

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