Year : 2010  |  Volume : 13  |  Issue : 1  |  Page : 22--27

Postoperative management of pulmonary endarterectomy and outcome


Ramakrishna M Narayana Iyengar, Deviprasad Hegde, Binoy Chattuparambil, Ratan Gupta, Lakshmi Patil 
 Narayana Hrudayalaya Institute of Medical Sciences (Current affiliation: Sagar Hospitals), Bangalore, India

Correspondence Address:
Ramakrishna M Narayana Iyengar
MN, #77,4th Cross, Duo Heights Layout, Devarachikkanahalli, Begur Post, Bangalore
India

Abstract

Pulmonary artery thromboendarterectomy (PTE) has been regarded as a promising, potentially curative surgical procedure. However, PTE is associated with specific postoperative complications, such as reperfusion pulmonary edema and right heart failure leading to a considerable mortality of 7-24%. Despite its limitations PTE is a better surgical alternative to lung transplantation which carries high morbidity and mortality. The aim of the study is to analyze the efficacy, safety, morbidity and survival associated in the postoperative period and quality of life after six months of PTE in Indian patients. Forty-one patients with surgically correctable chronic thromboembolic pulmonary hypertension underwent pulmonary endarterectomy. All patients were in New York Heart Association (NYHA) Class II, III or IV. Preoperative mean pulmonary artery pressure was 40.98 ± 9.29 mmHg and mean pulmonary vascular resistance was 418.39 ± 95.88 dynes/sec/cm -5 . All patients were followed up to six months and a telephonic survey was conducted using a standard questionnaire. They were assessed and classified as per NYHA grading. There was a significant reduction in the mean pulmonary artery pressure (from 40.98 ± 9.29 mmHg to 24.13 ± 7.36 mmHg, P < 0.001) and pulmonary vascular resistance (from 418.39 ± 95.88 dynes/sec/cm -5 to 142.45 ± 36.27 dynes/sec/cm -5 , P < 0.001) with a concomitant increase in the cardiac index (from 1.99 ± 0.20 L/min/m 2 to 3.28 ± 0.56 L/min/m 2 , P < 0.001) during the postoperative period. The mortality rate in our study was 12.19% (five patients). Ninety per cent of the patients reported a significant improvement in the quality of life and exercise tolerance after surgery compared to the preoperative state. Pulmonary endarterectomy is an effective and potentially curative surgical treatment for patients with severe chronic thromboembolic pulmonary hypertension. The current techniques of operation make the procedure relatively safe and long-term survival, NYHA functional status and exercise capacity improve significantly.



How to cite this article:
Narayana Iyengar RM, Hegde D, Chattuparambil B, Gupta R, Patil L. Postoperative management of pulmonary endarterectomy and outcome.Ann Card Anaesth 2010;13:22-27


How to cite this URL:
Narayana Iyengar RM, Hegde D, Chattuparambil B, Gupta R, Patil L. Postoperative management of pulmonary endarterectomy and outcome. Ann Card Anaesth [serial online] 2010 [cited 2019 Sep 22 ];13:22-27
Available from: http://www.annals.in/text.asp?2010/13/1/22/58830


Full Text

 Introduction



Chronic thromboembolic pulmonary hypertension is an insidious and often unrecognized disease that has been ignored for a long time. Diagnosis is often delayed or overlooked. Chronic thromboembolic pulmonary hypertension is associated with considerable morbidity and mortality. In general, prognosis is poor: the five-year survival in patients with a mean pulmonary artery pressure (mPAP) of more than 40 mmHg is only 30% and that in patients with mPAP exceeding 50 mmHg is only 10%. [1],[2],[3],[4]

Important advances in diagnosis such as computerized tomographic pulmonary angiography, magnetic resonance imaging, radionuclide ventilation/perfusion lung scan, surgical techniques such as adequate cerebral protection strategies, endarterectomy of segmental and lobar branches, and postoperative management such as elective ventilation, aggressive diuresis, low-dose inhaled nitric oxide therapy, use of prostacyclins, and other modalities have greatly improved the prognosis of this debilitating disease.

Although pulmonary transplantation is still used in some centers for patients with thromboembolic disease, complications outweigh the benefits. The pulmonary artery thromboendarterectomy (PTE) operation performed by an experienced surgeon carries a lower operative mortality rate than lung transplantation. The operation can be performed electively without waiting for a donor, and the long-term problems associated with rejection and immunosuppressive drugs are eliminated. In addition, the mortality rate for transplantation (and especially double lung transplantation) as a therapeutic strategy should include patients on the waiting list and is therefore much higher than is generally reported. [4]

PTE is an established curative surgical therapy for patients with chronic thromboembolic pulmonary hypertension. It includes a bilateral endarterectomy made via a median sternotomy under total cardiopulmonary bypass and deep hypothermia ( of an average 35 min duration in order to manage the bleeding from the systemic to pulmonary artery circulation. [4]

Patients suffering from chronic thromboembolic pulmonary hypertension have severe limitations during exercise, and sometimes even at rest, mainly because of a ventilation/perfusion mismatch and pulmonary hypertension leading to chronic right heart failure. [5] Therefore, PTE has been regarded as a promising, potentially curative surgical procedure since its introduction approximately 30 years ago. [6],[7] However, PTE is associated with specific postoperative complications, such as reperfusion pulmonary edema and right heart failure, leading to considerable mortality of 7-24%. [8],[9],[10] Reperfusion pulmonary edema (RPE) is characterized by sustained arterial hypoxemia caused by focal pulmonary infiltrates in regions distal to the vessels subjected to endarterectomy. [11] RPE after PTE requires prolonged postoperative mechanical ventilation (MV) (>72 h) and intensive care treatment with its potential risks and side-effects. [12],[13]

The aim of the study is to analyze the efficacy, safety, morbidity and survival associated in the postoperative period and quality of life after six months of PTE in Indian patients.

 Materials and Methods



Between January '08 and January '09, a total of 41 consecutive patients undergoing PTE were included. All the data were collected prospectively. Study was approved by the hospital ethical committee and an informed consent was taken from all patients. Patients accepted for surgery included those with pulmonary artery hypertension and evidence of thromboembolic disease which was confirmed on computerized tomograghic pulmonary angiography. All patients were subjected to echocardiogram and coronary angiogram.

Preoperative pulmonary artery pressure, cardiac index and pulmonary vascular resistance were measured prior to surgical incision. In the postoperative period the same values were compared after 24 h.

All the operations were performed by one surgeon with the standardized technique using extracorporeal circulation and intermittent periods of circulatory arrest under deep hypothermia.

Postoperative care was protocol-based, which included elective mechanical ventilation for a minimum of 48 h with a maximal inspiratory pressure maintained below 30 cm of water and fractional inspired oxygen level is kept below 0.5 ensuring oxygen saturation of over 90% and aggressive diueresis along with other standard care followed for open heart surgeries.

Anticoagulation was reinitiated within 6-8 h postoperatively in all the patients. All patients were started on sildenafil citrate 25 mg three times daily from first operative day onwards.

Standard monitoring consisted of invasive arterial blood pressure, Swan-Ganz catheter for pulmonary artery pressure and continuous cardiac output monitoring, once daily chest X-ray, 2D-Echo and arterial blood gases.

Weaning was initiated with spontaneous breathing trial after achieving stable hemodynamics with minimal ionotropic supports. The spontaneous breathing trial was continued for 4-6 h. Based on the hemodynamic parameters and extubation criteria patients were either extubated or continued on mechanical ventilation.

Three weaning trials were given every day for patients who did not meet extubation criteria, to be labelled as weaning failure and those patients were subjected to tracheostomy. The predictors of prolonged mechanical ventilation in the postoperative period were postoperative severe pulmonary artery hypertension, neurological complication, pulmonary hemorrhage and RPE.

The hemodynamic data, ICU stay, morbidity and survival were analyzed. All patients were followed up to six months and a telephonic survey was conducted using a standard questionnaire [Annexure 1]-[SUPPORTING:1]. They were assessed and classified as per NYHA grading.

Statistical analysis

Values are summarized as mean ± standard deviation or n (%). Paired t test statistical analysis was applied to compare preoperative and postoperative hemodynamic parameters. Values of P Preoperative data

The preoperative baseline characteristics are presented in [Table 1]. Mean age of the patient was 41.33 years with male preponderance. Only 58.53% of patients gave previous history of deep venous thrombosis. Signs of right ventricular failure like edema, jaundice, ascites and raised jugular venous pressure were present in 46.34% of patients. Out of 41 patients, seven (17.07%) were tested positive for antiphospholipid antibody, and two (4.87%) were having protein C/S deficiency. These abnormalities were observed predominantly in the younger age group (Intraoperative data

The mean cardiopulmonary bypass time was 245±70.23 min. The mean aortic cross clamp time was 171 ±53.40 min and mean intermittent circulatory arrest time was 25.95±11.59 min.

Among 41 patients, 36 patients underwent PTE and in five, combined tricuspid annuloplasty was performed.

Postoperative data

The mean preoperative mPAP was 40.98±9.29 mmHg; mean cardiac index was 1.99±0.20 L/min/m 2 and mean pulmonary vascular resistance was 418.39±95.88 dynes/sec/cm. [5]

When we analyzed and compared hemodynamic data, it was found that there was a significant reduction in mean PAP, pulmonary vascular resistance and significant improvement in the cardiac index in the postoperative period. [Table 3] presents the mean change between pre and postoperative hemodynamic parameters of PAPs, pulmonary vascular resistance and cardiac index.

Protocol-based mechanical ventilation for minimum of 48 h was followed. In our study the mean duration of mechanical ventilation was 75.16 h. In those patients subjected to elective tracheostomy, the duration of mechanical ventilation prior to tracheostomy was considered .

All patients were initiated with inotropes in the intraoperative period and titrated as per requirement in the postoperative period. The mean duration of requirement of at least one inotrope in our study was 6.28 days.

Intermittent noninvasive ventilation was required in nine patients (25%) after extubation for 24-48 h. A severe form of RPE was seen in two patients (5.55%) and none of the survivors had pulmonary hemorrhage. Of the two patients who had RPE one patient had to be supported with extracorporeal membrane oxygenation (ECMO) in the postoperative period.

Late complications seen were similar to any other major open heart surgery; severe sepsis was seen in five patients (13.88%), nonoliguric acute renal failure in nine patients (25%), of which two patients (5.5%) required renal replacement therapy. A total of five patients (13.88%) were subjected to elective tracheostomy either due to anticipated prolonged MV or weaning difficulty. Post tracheostomy mean duration of MV was 10.8 days.

The mean ICU stay of patients who survived was 11.25 days. The mortality rate in our study was 12.19% (five patients) of which two patients had significant pulmonary hemorrhage in the immediate postoperative period. In our study we encountered two cases of pulmonary hemorrhage and one case of severe RPE. All patients with the above complications required ECMO, but in only one patient ECMO was successfully weaned and two patients with pulmonary hemorrhage died. Other mortalities seen were either due to sepsis associated with multiorgan failure (two) or stroke (one) [Table 4].

Quality of life: [Annexure 1] - [SUPPORTING:1]

Of the 36 survivors, we were able to establish contact with 30. Among these, 27 (90%) had good quality of life, were free of preoperative symptoms and having good exercise tolerance (walking more than 20 min.), three patients (10%) had fair quality of life with minimal limitations in the routine daily activities. None of these patients required readmission related to the surgery/anticoagulation or death .

 Discussion



PTE is a complex surgical procedure, which is performed in a few selected centers in India. It is considered curative with significant and sustained functional hemodynamic improvement in the majority of the patients with chronic thromboembolic pulmonary arterial hypertension. [14] In this regard, our study showed significant reduction in PAP, pulmonary vascular resistance and corresponding improvement in cardiac index [Table 3].

Postoperative management in these patients plays a significant role because of complications such as RPE, pulmonary hemorrhage, ventilation perfusion mismatch etc. [14,15] To overcome these problems, we developed protocol-based postoperative management. These included postoperative MV for more than 48 h, use of low tidal volume and PEEP. The pharmacological adjuncts used were, methylprednisolone for three postoperative days, heparin therapy commencing 6-8 h postoperatively and, oral warfarin thereafter, aggressive diuretic therapy and sildenafil citrate. These measures were improvised gradually as we gained experience in managing these patients. An early tracheostomy was planned whenever the anticipated duration of MV was more than five days. Continuous cardiac output and its derivatives' monitoring, serial echocardiography, serial chest X-rays, acid base gases were the mainstay of postoperative monitoring and based on these values, the postoperative management was fine-tuned.

In patients with chronic pulmonary embolism, a ventilation-perfusion mismatch and concomitant decrease of cardiac output and venous oxygen saturation are the most important reasons for marked hypoxemia. [11],[16] By performing endarterectomy of pulmonary artery branches, perfusion of non-perfused lung areas is re-established and cardiac output is increased [16],[17] This was clearly evident in our study where the majority of our patients had improved cardiac index and pulmonary vascular resistance [Table 3]. The results obtained in our series demonstrated a marked improvement in clinical and hemodynamic parameters in most of the patients after primary successful surgery.

Postoperative management of PTE surgery has its own complications when compared to other open heart surgeries. Most commonly seen in early peri-operative course are RPE and pulmonary hemorrhage. In our study we encountered two cases of pulmonary hemorrhage and one case of severe RPE. All patients with the above complications required ECMO but in only one patient ECMO was successfully weaned. Nine patients (25%) required noninvasive ventilation support for a brief duration due to mild form of RPE .

Late complications encountered in our study were sepsis, acute renal failure; cerebrovascular accident and difficulty in weaning from ventilator. Five patients (13.88%) were subjected to elective tracheostomy due to weaning difficulty. The mean duration of MV post tracheostomy was 10.8 days. Mean ICU stay in the study group was 11.25 days, which was comparable to previous studies.

Mortality in our study group was 12.19% which was marginally higher compared to other international studies with a larger sample size but when compared to smaller studies the results were almost similar [Table 5]. We also attributed the finding to the fact that most of the deaths in our group were encountered in the early part of the study as well as to the smaller sample size. With better surgical experience and improvisation of protocol-based postoperative management, the incidence of mortality reduced significantly.

Quality of life

In view of inadequate follow-up and technical difficulties in performing invasive procedures during the follow-up, we did a six months postoperative follow-up assessment telephonically. We had prepared a questionnaire to collect the information to classify them as per the NYHA grading.

We found that 90% of the patients reported a significant improvement of the quality of life and exercise tolerance after surgery. Before surgery, most patients were in NYHA functional Class II or III; after surgery, more than 90% of them are in Class I and able to resume normal activities.

 Conclusion



Pulmonary endarterectomy is an effective and potentially curative surgical treatment for patients with severe chronic thromboembolic pulmonary hypertension. Based on our experience of a multidisciplinary team, the operative risk and six-month survival has been reduced to an acceptable level , NYHA functional status and exercise capacity improved significantly. Medical therapy for this disease is palliative, and ineffective in prolonging life. If lung transplantation is considered as an option in such patients, the problems of higher mortality, immunosuppression and allograft rejection are likely complications to be expected. Therefore, it should be considered only in patients unfit for pulmonary thrombectomy.[22]

References

1Dartevelle P, Fadel E, Mussot S, Chapelier A, Hervé P, de Perrot M. Chronic thromboembolic pulmonary hypertension. Eur Respir J 2004;23:637-48.
2Cerveri I, D'Armini AM, Viganò M. Pulmonary thromboendarterectomy almost 50 years after the first surgical attempts. Heart 2003;89:369-70.
3Lewczuk J, Piszko P, Jagas J, Porada A, Wójciak S, Sobkowicz B, et al. Prognostic factors in medically treated patients with chronic pulmonar embolism. Chest 2001;119:818-23.
4Jamieson SW, Kapelanski DP, Sakakibara N, Manecke GR, Thistlethwaite PA, Kerr KM, et al. Pulmonary endarterectomy: experience and lessons learned in 1,500 cases. Ann Thorac Surg 2003;76:1457-64.
5Moser KM, Spragg RG, Utley J, Daily PO. Chronic thrombotic obstruction of major pulmonary arteries. Results of thromboendarterectomy in 15 patients. Ann Intern Med 1983;99:299-305.
6Hurwitt ES, Schein CJ, Rifkin H, Lebendiger A. A surgical approach to the problem of chronic pulmonary artery obstruction due to thrombosis or stenosis. Ann Surg 1958;147:157-65.
7Daily PO, Johnston GG, Simmons CJ, Moser KM. Surgical management of chronic pulmonary embolism: surgical treatment and late results. J Thorac Cardiovasc Surg 1980;79:523-31.
8Moser KM, Braunwald NS. Successful surgical intervention in severe chronic thromboembolic pulmonary hypertension. Chest 1973;64:29-35.
9Daily PO, Dembitsky WP, Iversen S, Moser KM, Auger W. Risk factors for pulmonary thromboendarterectomy. J Thorac Cardiovasc Surg 1990;99:670-8.
10Hartz RS, Byrne JG, Levitsky S, Park J, Rich S. Predictors of mortality in pulmonary thromboendarterectomy. Ann Thorac Surg 1996;62:1255-60.
11Mayer E, Dahm M, Hake U, Schmid FX, Pitton M, Kupferwasser I, et al. Mid-term results of pulmonary thromboendarterectomy for chronic thromboembolic pulmonary hypertension. Ann Thorac Surg 1996;61:1788-92.
12Utley JR, Spragg RG, Long WB 3rd, Moser KM. Pulmonary endarterectomy for chronic thromboembolic obstruction: recent surgical experience. Surgery 1982;92:1096-102.
13Levinson RM, Shure D, Moser KM. Reperfusion pulmonary edema after pulmonary artery thromboendarterectomy. Am Rev Respir Dis 1986;134:1241-5.
14Thistlethwaite PA, Kaneko K, Madani MM, Jamieson SW. Technique and outcomes of pulmonary endarterectomy surgery. Ann Thorac Cardiovasc Surg 2008;14:274-82.
15Kapitan KS, Buchbinder M, Wagner PD, Moser KM. Mechanisms of hypoxemia in chronic thromboembolic pulmonary hypertension. Am Rev Respir Dis 1989;139:1149-54.
16Kapitan KS, Clausen JL, Moser KM. Gas exchange in chronic thromboembolism after pulmonary thromboendarterectomy. Chest 1990;98:14-9.
17Brown DL, Bodary AK, Kirby RR. Anesthetic management of pulmonary thromboendarterectomy. Anesthesiology 1984;61:197-200.
18Moser KM, Auger WR, Fedullo PF. Chronic major-vessel thromboembolic pulmonary hypertension. Circulation 1990;81:1735-43.
19Moser KM, Auger WR, Fedullo PF, Jamieson SW. Chronic thromboembolic pulmonary hypertension: clinical picture and surgical treatment. Eur Respir J 1992;5:334-42.
20Jamieson SW, Auger WR, Fedullo PF, Channick RN, Kriett JM, Tarazi RY, et al. Experience and results with 150 pulmonary thromboendarterectomy operations over a 29-month period. J Thorac Cardiovasc Surg 1993;106:116-27.
21Mayer E. Surgical treatment of chronic thromboembolic pulmonary hypertension. Swiss Med Wkly 2006;136:491-7.
22Dartevelle P, Fadel E, Mussot S, Chapelier A, Hervé P, de Perrot M, et al. Chronic thromboembolic pulmonary hypertension. Eur Respir J 2004;23:637-48