Objectives: To assess the early outcome after elective isolated or concomitant mitral valve replacement (MVR) in patients with pulmonary hypertension (PH). Subjects and methods: The study included patients with baseline systolic pulmonary artery pressure (PAPs) of at least 35 mmHg measured by echo who underwent elective MVR and/or aortic valve replacement (AVR).
Trang 1EVALUATION THE CRITICAL CARE PERIOD RESULTS AFTER
ISOLATED MITRAL VALVE REPLACEMENT OR
SIMULTANEOUS MITRAL AND AORTIC VALVE SURGERY IN
PATIENTS WITH PULMONARY HYPERTENSION
Kieu Van Khuong*; Pham Thi Hong Thi**; Nguyen Quoc Kinh***
SUMMARY
Objectives: To assess the early outcome after elective isolated or concomitant mitral valve replacement (MVR) in patients with pulmonary hypertension (PH) Subjects and methods: The study included patients with baseline systolic pulmonary artery pressure (PAPs) of at least
35 mmHg measured by echo who underwent elective MVR and/or aortic valve replacement (AVR) The systemic and pulmonary hemodynamic changes, arterial and mixed venous blood gas parameters were reported at various time points before and after operation Preoperative and postoperative transthoracic echocardiography was performed Results: Sixty seven patients (15 males and 52 females), arithmetic mean age was 45.51 ± 10.74 years (min - max: 20 - 68) were included in the study The operative mortality rate was 4.5% The receiver operating characteristic curves identified PAPs as a good predictor of operative mortality Postoperatively, there was a significant reduction in left atrial diameter (LAd) The arithmetic mean PAPs and pulmonary artery occlusion pressure (PAOP) decreased significantly after cardiopulmonary bypass (CPB) and persisted throughout the study period Central venous pressure (CVP) decreased after CPB time and remained so to PAC removing time point, postoperatively A decrease in SvO 2 was significant after operation Conclusion: Proper perioperative care and anesthetic techniques resulted in the improvement of LAd, PAPs, PAOP, with acceptable operative mortality in patients with PH who was performed elective isolated MVR or simultaneous mitral and AVR
* Keywords: Pulmonary hypertension; Aortic valve replacement; Mitral valve replacement
INTRODUCTION
All around the world, rheumatic heart
disease remains a major health problem,
although its prevalence in the developed
countries is much reduced Involvement
of the mitral valve and aortic valve results
in stenosis and/or regurgitation heart valve diseases Where surgery is indicated, MVR is usually necessary [1] The development of pulmonary arterial hypertension (PAH) has been considered
a risk factor for poor outcomes in patients undergoing MVR and/or AVR [2] However,
* 103 Military Hospital
** Vietnam National Heart Institute
*** Vietduc Hospital
Corresponding author: Kieu Van Khuong (icudoctor103@gmail.com)
Date received: 10/12/2017 Date accepted: 22/01/2018
Trang 2there is no consensus on the outcome of
patients with PAH after MVR in the
literature; some studies have shown that
severe PAH is associated with poorer
outcome and higher mortality rate [3],
whereas others do not agree that severe
PAH implies a higher risk during corrective
surgery [4, 5, 6, 7]
This study was designed to: Assess
the early clinical, hemodynamic, and
echocardiographic changes after elective
isolated MVR or concomitant MVR and
AVR in patients with PH
SUBJECTS AND METHODS
1 Subjects
Between April, 2017 and November,
2017, 67 consecutive adult patients with a
baseline PAPs of at least 35 mmHg (as
measured by preinduction transthoracic
echocardiography) who had performed
mitral and/or simultaneous AVR at Heart
Center of Hue Center Hospital Patients
with coronary artery disease or idiopathic
PAP were excluded from the study
2 Methods
All preoperative assessments were
carried out by two-dimensional transthoracic
echocardiography A pulmonary artery
catheter (PAC) was placed in the pulmonary
artery to measure PAPs and PAOP
General anesthesia was induced with
fentanyl, 3 - 5 µg/kg All patients were
operated on through a arithmetic mean
sternotomy on CPB with moderate general
hypothermia (28 - 30°C) We used two
kinds of mechanical prosthesis: ATS valve
and St Jude medical bileaflet mechanical
prosthesis The hemodynamic and arterial blood gas parameters were reported at time points: T0: baseline or pre-induction; T1: intubation; T2: immediate post-CPB; T3: at ICU; T4: 6 hour post-ICU; T5:
24 hour post-ICU and Toff: before PAC removing and the hemodynamics had been stabilized postoperatively Hemodynamic parameters that were recorded included mean arterial pressure (MAP), PAPs, PAOP, and central venous pressure (CVP) All data were expressed as mean
± standard deviation, min - max or number and percent as appropriate The preoperative and postoperative echocardiographic parameters, and the hemodynamic and arterial blood gas parameters obtained at various time intervals were compared with the baseline values The receiver operating characteristic (ROC) curves were used to estimate the relationship between sensitivity (proportion
of true positive cases) and 1-specificity (proportion of false-positive cases) of PAPs in the prediction of operative mortality A p-value of 0.05 or less was considered significant
RESULTS
Table 1: Patient’s characteristics
Variables Result Min - max
(22.4/77.6) Body surface area (m2) 1.44 ± 0.11 Body mass index
(kg/m2)
19.8 ± 2.4 15.4 - 25.2
Trang 3Weight (kg) 48.0 ± 6.5 33 - 67
Atrial fibrillation (n, %) 31 (46.3)
Cardiothoracic ratio
> 50% (n, %)
40 (59.7)
The study group was mainly female
(77.6%) at arithmetic mean age of 45.51 ±
10.74 years The patients were classified
as follows: 21 patients (31.3%) in NYHA II
class and 44 patients (65.7%) in NYHA III
class and 2 cases in NYHA class IV
Table 2: Intraoperative and postoperative
clinical outcome variables
Variables Result Min -
Max
CPB time (min),
arithmetic mean
114.2 ± 57.7
54 - 466
ACC time (min),
arithmetic mean
79.8 ± 36.8
31 - 185
Tricuspid repair [n (%)] 15
(22.4%)
LAA exclusion [n (%)] 18 (26.9)
Thromboembolic
removing [n (%)]
11 (16.4)
Time of ventilator (h) 20.9 ±
31.7 Mechanical assist by
IABP [n (%)]
4 (6%)
Operative mortality
[n (%)]
3 (4.5%)
Cardiopulmonary bypass time; IABP:
Intra-aortic balloon pump; ICU: Intensive care unit LAA: Left atrial appendage)
The arithmetic mean CPB time was 114.18 ± 57.71 mins (range: 54 - 466) and the arithmetic mean aortic cross-clamp time was 79.76 ± 36.78 mins (range: 31 - 185) Tricuspid repair was performed in 15 patients (22.39%)
Table 3: Comparison of preoperative
and postoperative echocardiographic variables
Variables T0 T3 Toff
8.19b
42.13 ± 2.30b
43.67 ± 2.88b LVEDD
(mm)
48.28 ± 8.31b
45.92 ± 5.59b
45.45 ± 5.19b LVESD
(mm)
34.66 ± 7.15b
32.61 ± 5.40b
31.87 ± 5.31a
EF (%) 53.49 ± 8.02 53.28 ± 7.38 55.21 ± 8.22
(a: Significant difference < 0.0001; b: Significant difference < 0.05 Abbreviation:
EF: Ejection fraction; Lad: Left atrium diameter; LVEDD: Left ventricular end-diastolic diameter; LVESD: Left ventricular end-systolic diameter; CTR: Cardiothoracic ratio)
There was a significant difference between LAd, LVEDD, LVESD at points time of postoperation and when to remove PAC in comparision with baseline time results but no significant difference in EF
Trang 4Table 4: Early hemodynamic parameter changes
Time points CI (L/min/m 2 ) CVP (mmHg) MAP (mmHg) PAPs (mmHg) PAOP (mmHg)
T0 2.43 ± 0.77a 7.55 ± 4.11b 94.48 ± 12.41a 49.15 ± 17.52a 23.43 ± 9.84a
T4 2.65 ± 0.55a 6.10 ± 2.79b 74.00 ± 11.63a 32.18 ± 11.89a 9.91 ± 5.43a Toff 3.00 ± 0.69a 6.21 ± 3.20b 79.16 ± 10.70a 31.45 ±1 1.99a 9.63 ± 5.06a
(a: Significant difference < 0.0001; b: Significant difference < 0.05 Abbreviation: CI: Cardiac output index; CVP: Central venous pressure; MAP: Mean arterial pressure; POAP: Pulmonary artery occlusion pressure; PAPs: Pulmonary systolic arterial pressure)
There was a significant decrease in PAPs, PAOP after induction, CPB stop, and this change persisted throughout at removing PAC time point postoperatively CVP and MAP decreased, but it kept in normal range CI decreased after induction anesthesia (T1) and increased significantly at T2, T3, Toff time point
Table 5: Arterial and mixed venous blood gas parameter changes
Time points pH PaCO 2 (mmHg) PaO 2 (mmHg) SaO 2 (%) SvO 2 (%)
T1 7.48 ± 0.06a 32.48 ± 5.54a 319.56 ± 80.85a 99.94 ± 0.37b 72.37 ± 8.10
T4 7.39 ± 0.07b 36.29 ± 5.88b 163.98 ± 36.34b 99.14 ± 0.66 63.34 ± 12.43a Toff 7.45 ± 0.07b 39.46 ± 6.19 104.50 ± 36.74a 96.86 ± 2.67a 59.24 ± 11.17a
(a: Significant difference < 0.0001, b: Significant difference < 0.05)
There was a significant difference of blood gas parameters between baseline time point (T0 time point) with other time points, excepted PaCO2 (Toff time point), PaO2 (T2 time point), SaO2 (T2, T3, T4 time point) and SvO2 (T1, T2, T3 time point)
Trang 50 20 40 60 80 100
100-Specificity
Sensitivity: 66.7 Specificity: 85.9 Criterion : >65
Figure 1: The receiver operating characteristic curve of systolic pulmonary arterial
hypertension as a predictor of operative mortality
DISCUSSION
There were 67 patients involved in the
study, the lowest age was 20, the highest
was 68, the mean was 45.51 ± 10.74 years
This finding is consistent with recent studies
in cardiac valve surgery in India and
Vietnam The study by Nirmal Kumar et al
[7] in severe PH patients soon after MVR
had an arithmetic mean age of 32.1 years,
lower than our result This difference was
due to the fact that study only included
patients with mitral valve disease with
severe PH (PAPs > 50 mmHg) and this
feature was more common in acute
rheumatoid arthritis in India [10] Age in
our study was similar to result of Gökhan
Lafçı [4] and two other local authors: Vu
Quynh Nga (44.2 ± 11.5 years), Doan
Duc Hoang (46.69 ± 12.57 years) [1, 2]
The patients were mainly in NYHA III
with 46.3% rhythm dysfunction as atrial
fibrillation (AF) and 59.7% of them
increased cardiothoracic ratio over 50%
Some intraoperative and postoperative
results showed in table 2 The arithmetic
mean CPB time (114.2 ± 57.7 mins) and
the arithmetic mean ACC time (79.7 ±
36.8 mins) was similar to Xiaochun Song’s study (CPB: 119.9 ± 37.4 mins and ACC: 82.5 ± 31.8 mins) [7] Our result was higher than Vu Thuc Phuong’s study (CPB time of group D, using dobutamin: 95.2 ± 35.1 mins; CPB time of group E, using epinephrine: 86.5 ± 24.1 mins ACC time of group D: 73.5 ± 32.4 mins; ACC time of group E 67.2 ± 20.8 mins) It may
be due to their patient groups were mainly replaced one valve surgery (> 60% in both groups) and no preoperative heart failure
A comparison of preoperative and postoperative (T3 time point), removing PAC time point (Toff) echocardiographic variables is presented in table 3 Postoperatively, there was a significant reduction in LAd, LVEDD, LVESD (p < 0.05) The increased left atrial (LA) pressure in mitral valve disease is passively transmitted to the pulmonary vasculature and can lead to an increase in pulmonary vascular resistance (PVR) Some other factors such as reactive pulmonary vasoconstriction and organic changes in pulmonary vasculature are also responsible for this increase in PVR [11] Following mitral valve surgery, LA loading can
Trang 6be adequately decompressed This
decompression is very influential in the
regression of PH [4] LA enlargement is a
pathophysiological response to volume
overload resulting from valvular diseases
which is known as LA remodeling, and
has been shown previously to be associated
with cardioembolic events Following MVR,
the LA may undergo reverse remodeling
characterized by LA volume reduction LA
size reduces with the return of normal
sinus rhythm and a decrease in the
gradient across the mitral valve
Our results showed a significant decrease
in PAPs and PAOP after CPB (T2 time
point), and this change persisted to time
point of PAC removing, postoperatively
(table 4) These findings were in agreement
with some other researchers who have
reported hemodynamic changes in patients
with rheumatic mitral valve disease at
different intervals after MVR, with an
immediate reduction in PAPs In the study
by Kumar [9], the mean PAPs, PAOP, and
pulmonary vascular resistance decreased
significantly soon after CPB in patients
with severe PH The mean PAPs
approached near-normal values (26 ±
5 mmHg) 6 hours and 24 hours,
postoperatively The study by Mubeen et
al [12] showed that the mean PAPs
decreased by 38% from a mean
preoperative level of 59.8 to 37.1 mmHg
immediately following MVR Although it
continued to decrease over the next
24 hour, this further decrease was not
statistically significant In a recent study
by Bayat et al, PAP in patients with severe
PAH showed no significant reduction
immediately after MVR, but it decreased
significantly below the range of severe
PAP over the first 24 hours after operation
The present study showed that MVR could be performed in patients with rheumatic valvular disease and severe
PH with an acceptable operative mortality
of 10% The study by Mubeen et al [12] showed that the operative mortality was 5.5% in patients with subsystemic PAP, with a mean of 58.1 mmHg and 28.5% in patients with a suprasystemic PAP of 83.2 mmHg The operative mortality rate
in our study was 4.5% (table 2) The ROC curves (figure 1) identified PAPs as a good predictor of operative mortality (area under the ROC curve: 0.794; p < 0.05), and the value greater than 65 mmHg has the highest specificity (85.9%) and sensitivity (66.7%) for the risk of operative mortality in those patients Similarly, the recent study by Corciova et al identified PAPs value greater than 65 mmHg to have the highest specificity and sensitivity for the risk of perioperative death in mitral regurgitation patients (area under the ROC curve: 0.782; p < 0.001)
SvO2 did not change at T1, T2 time point (table 5) but it decreased significantly after operation even when hemodynamic
in stable (at Toff time point) SvO2 can be used to assess the adequacy of tissue perfusion and oxygenation When analyzing
in conjunction with other hemodynamic parameters, following trends in the SvO2
does offer insight into cardiac performance and tissue oxygen delivery In the postoperative cardiac surgical patient, a fall in SvO2 generally reflects decreased oxygen delivery or increased oxygen extraction by tissues and is suggestive of
a reduction in cardiac output However, other constantly changing factors that affect oxygen supply and demand may
Trang 7also influence SvO2 and must be taken
into consideration These include shivering,
temperature, anemia, alteration in FiO2,
and the efficiency of alveolar gas exchange
A decresae in SvO2 at T3, T4 time point
(patients in ventilation support) (table 5)
can result from a decrease CO, low
hemoglobin level or an increase in oxygen
consumption SvO2 decreased at Toff
may be relative with a decrease in FiO2
(in room air), fever or anemia It is very
important to take care the patients in this
stage because SvO2 reduction under
threshold leads to the danger of organ
dysfunction that is reason why they come
back to intensive care unit ward
CONCLUSION
Isolated MVR or concomitant MVR and
AVR was safe and effective even in
patients with PH, with acceptable operative
mortality and a significant improvement in
left atrial diameter, pulmonary hemodynamics
(PAPs, PAOP), but a decrease in mixed
venous saturation early after operation
The anesthetic technique and perioperative
care can be useful in improving the
outcome in such patients
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