đánh giá sức cản động mạch phổi (pvr) bằng phương pháp siêu âm- doppler tim ở bệnh nhân hẹp hai lá (hhl) khít trước và sau nong van bằng bóng bản tóm tắt tiếng anh

POSITION OF THE PROBLEM 1- Importance of the problem: Mitral stenosis (MS) is the situation that occurs when the mitral commissures are sticked together inducing diastolic narrowing of the mitral opening surface, impeding thus blood flow from the left atrium (LA) into the left ventricle (LV), hence increasing left atrial pressure, and in the long term, increasing pulmonary capillary pressure due to swollen pulmonary veins, then increasing pulmonary pressure (PP), and pulmonary vascular resistance (PVR), leading to right ventricular overload, finally right ventricular failure. Percutaneous transmitral commissurotomy (PTMC) is an effective method of non surgical enlargement of the mitral opening surface. World literature showed an important role of PVR in the pathophysiology of MS, that contributes to the assessment, follow-up of treatment and prognosis, being the most sensitive indice of assessment of the diseased pulmonary artery. Some studies found the reversibility of PVR, but PVR might remain fixed though surgery or PTMC have been carried out, and the prognosis in those patients was worse than in those with reversible PVR. In the contrary, quite a few number of patients have seen their PVR and pulmonary artery pressure (PAP) notably decreased after successful procedures, surgical or with PTMC. Cardiac catheterization was the only method of assessment of PVR, but the procedure is invasive that could not be performed in any Health center, and repeated several times on the patient. Since 1980, non invasive assessment of PVR with cardiac Doppler ultrasound has been carried out, but in Vietnam so far, such a method 1 has not been studied, in patients with tight MS as well as the follow- up of post PTMC. Our work: “Assessment of pulmonary resistance with cardiac Doppler ultrasound in patients with tight mitral stenosis pre and post PTMC” has been carried out with the following objectives: 1. To study the PVR in patients with tight MS with Doppler cardiography (with head to head comparison with the PVR as in cardiac catheterization) and with a number of factors related to PVR. 2. To study changes of PVR post PTMC and a number of influencing factors. 2- Contributions of this thesis This is the first scientific work ever with a systematic study of PVR with Doppler cardiography in patients with tight MS treated with PTMC. This is a simple procedure, easy to perform, and susceptible to contribute to assessing post PTMC results in patients with tight MS. The results may broaden the use of Doppler cardiography in provincial polyclinics having their department of Cardiology. PRESENTATION OF THE THESIS The thesis comprises 115 pages in size A4, repartitioned in 4 chapters, dealing with 2 pages for Position of the problem, 30 pages for the Overview, 17 pages for the Material and Method, 32 pages for the Study results, 32 pages for the Discussion, 1 page for the Conclusions, and 1 page for the Recommendations. 2 CHAPTER I OVERVIEW 1.3. Pathophysiology of MS Pathophysiological changes vary following the severity of MS: 1.3.1. Increased transmitral gradient 1.3.2. Decreased transmitral blood flow and decreased cardiac output This decrease is mainly due to mechanical cause following severe MS, and not LV failure. 1.3.3. Increased PVR and PP LA pressure is usually not markedly increased with mild or moderate MS. The mean LA pressure (mLAP) is usually>10mmHg, sometimes 15-20 mmHg with tight MS. When the mitral stenosis is important, the increased LAP wil be followed by increased pulmonary veins and capillaries, and increased PAP (reactionary pulmonary hypertension, or post capillary pulmonary hypertension). The ever increase of PAP will induce retraction at the level of pulmonary arterioles, a reaction to pulmonary hypertension, thus induce increased PVR, and increased PP (this is now mixed pulmonary hypertension, both pre and post capillary). Pre capillary pulmonary hypertension is related to pulmonary arteriolar lesions, a consequence of reactionary retraction of pulmonary arterioles to the increase of LA and pulmonary pressures. The prolonged retraction will have deleterious consequences on the pulmonary arterioles and alveolar arterioles, leading to restructuring and fibrosis of the arteriolar walls, hence irreversible lesions at this level. The final result is, a second barrage from pulmonary arterioles is formed in 3 addition to the impeded LA-LV blood flow due to MS, that is called “the second barrage” or “the second stenosis”. Former belief was that any intervention would exert little impact on the outcome of MS at this stage, but clinical findings and a number of studies have shown improvement with time following the procedures on MS 1.3.4. Changes in the stress test Only severe MS present with major changes in the stress test. 1.3.5. Changes in the LA Prolonged increased LA pressure induces dilated LA, structural changes in the LA wall, that favours atrial fibrillation, and the formation of thrombus, a cause of stystemic embolization. 1.3.6. Changes in the RV The RV increases contractions for ensuring necessary blood supply for the body when the pulmonary pressure and resistance are elevated, resulting in RV hypertrophy, RV dilatation, tricuspid regurgitation induced by dilatation of the tricuspid ring (TR). 1.3.7. Changes in the LV Around 25-30% of patients present with slight decrease of LV function, probably due to long term decrease of blood flow into the LV. 1.5. MS manifestations in the clinic and laboratory 1.5.1. Clinical manifestations: Dyspnea, cardiac asthma and acute pulmonary edema, hemoptisis. 1.5.2. Laboratory 1.5.2.1. EKG: Possible LA hypertrophy, righ axis deviation, RV hypertrophy, atrial fibrillation is fairly common. 4 1.5.2.2. Chest Xray: Prominent cardiac left border with presence of 4 arches, pulmonary vascular congestion, presence of esophageal compression at inferior 1/3 rd with barium ingestion. 1.5.2.3. Cardiac Doppler ultrasound: A very important exploration. a. TM mode: In most cases of tight MS, the EF diastolic slope is < 15mm/sec. b. 2D mode : Allows direct assessment of mitral orifice, commonly used as the result is close to the mitral anatomy. c. Trans Esophageal Echography (TEE): Allows detect intraatrial and intra appendage thrombus more easily, and favours more accurate assessment of valvular and subvalvular lesions. d. Doppler ultrasound : Of particular importance in the assessment of the severity of MS - Assessment of mitral valve area with pressure half time (PHT). - Assessment of the MS severity with transmitral pressure gradient. e. Ultrasound stress test The test is indicated in case of symptoms present but tight MS is not found with echo at rest, or symptoms absent but tight MS is found with echo. - Asessment of valve and subvalvular anatomy in MS: Wilkins score (Table 1.2). For isolated MS, the optimal Wilkins score for indicating PTMC is ≤ 8. The procedure should be discarded if Wilkins ≥ 11, for the patient’s safety. 1.6. Treatment for MS: Medical, surgical, and PTMC. 5 1.7. Methods of assessing PVR 1.7.1. Catheterization PVR is calculated as follows: PVR = (PAPm – LAPm)/Qp (Woods Units – WU) PAPm:mean pressure of PA (mmHg), LAPm:mean pressure of LA (mmHg), Qp: pulmonary blood flow (l/min). In case of no intracardiac shunt, Qp is considered equal to systemic output. Two often used methods of assessment of cardiac output : Thermal dilution and Fick’s method. 1.7.2. Cardiac Doppler ultrsound A host of studies have been carried out for assessing PVR with cardiac Doppler ultrasound; in 2003, in the USA, Abbas AE et al gave the following formula as the result of their study: PVR = TRV / TVIrvot x 10 + 0.16 PVR: Pulmonary vascular resistance – in Woods units TRV: Maximal velocity of tricuspid regurgitant jet – in m/sec TVIrvot: integral of time velocity at the right venticular outflow tract – in cm. The formula has been included into Harvey Feigenbaum’s 2005 teaching program of ultrasound, and has been used by several authors in the assessement, follow-up of results of treatment of pulmonary hypertension, of capability to strain of MS patients, as well as in patients with organ grafting. 1.8. Relationship between PVR and involved parameters In 1997, Kim et al found a correlation between PVR and mitral orifice surface (r = -0.54) and the level of dyspnea NYHA. The 6 authors did not find any correlation between PVR and age, gender, and pre PTMC of mitral valves regurgitation. In 1999, Gamra et al found that in elderly patients, AF, high Wilkins’scoring, are risk factors having negative impact on the return to normal of PVR. CHAPTER 2 MATERIAL AND METHOD 2.1. Material 204 patients with tight MS have been PTMCed with Inoue balloon at Viet Nam Heart Institute (VNHI), and the control group of 116 normal adults with similar repartition in age range, and gender. Duration of study: 7/2006 – 8/2008. 2.1.1. Selection criteria - Tight MS (MVA < 1.5cm 2 ) and symptoms present (NYHA ≥ II). - Wilkins score ≤ 10. - Absence of LA thrombus on transthoracic echo (in patients on sinus rhythm) or TEE (in AF or high risk of having thrombus). - Isolate tight MS or tight MS with mild Mitral regurgitation (MR) or mild Aortic regurgitation (AR). 2.1.2. Exclusion criteria - Heavily diseased mitral valve and sub- valvular tissue (heavily thickened valves, important calcification, serious morphological changes, quite shortened chordae tendinae…) with Wilkins score >10. - LA thrombus. - Anamnesis of embolization within 3 months, even without echo findings. 7 - Concomitant respiratory diseases (bronchial asthma, COPD), Systemic diseases…and other diseases inducing pulmonary hypertension. - Concomitant Tricuspid stenosis - Absence of TR or very mild TR not allowing the measurement of regurgitant spectrum maximal velocity. - MVA < 1.5cm 2 after PTMC. 2.2. Method of study 2.2.1. How to devise the study: Longitudinal, cross-sectional study. 2.2.2. Steps undertaken All individuals involved in the study have been scrutinized clinically and laboratory data with transthoracic echo according to prepared file. TEE is added for all cases with AF to ascertain/ rule out the presence of LA thrombus. - All cases with an indication for PTMC have been chosen after consultation at VNHI. - Clinical examination and cardiac ultrasound re-checked 24hrs before PTMC. - All cases have been PTMCed with Inoue balloon at VNHI cathlab. - 34 patients with tight MS have been catheterized prior to PTMC. - Clinical and cardiac Doppler ultrasound rechecks: Post PTMC: 24 hours, 3 months, 6 months, 1 year. 2.2.3. How to carry out cardiac Doppler ultrasound - The examination has been carried out at VNHI echo lab.on ALOKA 5000, 2 transducers: 2.5 and 5MHz, M, 2D, Doppler (pulsed, continuous, colour coded). 8 Cardiac Doppler ultrasound parameters: M mode: Parameters related to cardiac morphology and function (ACC criteria). 2D mode: Assessment of the morphology of valves, subvalvular area, valvular commissures. Assessment of MVA (left side of sternum, short axis) Cardiac Doppler ultrasound: MVA: PHT method. Pressure gradients: Max and Mean Assessment of MR : 3 levels of severity. Assessment of TR : 3 levels of severity. Assessment of Pulmonary pressure (PP) based on 4 chamber axis with continuous Doppler ultrasound transducer from the cardiac apex. PAPs = (TRV) 2 + RAPs PAPs = pulmonary systolic pressure (mmHg) RAPs = RA systolic pressure TRV = Maximal velocity of TR spectrum (m/sec) As RAPs is estimated 10mmHg, then PAPs = (TRV) 2 + 10 (mmHg) Based on the pulmonary systolic pressure, we have 3 levels of Pulmonary hypertension (PH) (fig 2.6). - PH as by measuring the maximal velocity of the TR spectrum (Fig. 2.7). - PH as by assessing the time integral velocity of blood flow at the RVOT (TVIrvot): Location: left side of sternum, short axis, using pulsed Doppler. • Assessment of PVR with cardiac Doppler ultrasound: Using the Abbas Amr E : PVR = TRV/TVIrvot x 10 + 0.16 9 2.3. Data processing a. Medical statistical method using software SPSS 15.0 b. The results are presented as the mean ± standard deviation (for variants) or % (with logic variants) c. Paired t test used for comparing pre and post PTMC results. Statistical significance when p<0.05 d. r is the correlation coefficient : - │r│< 0.3 : Weak correlation - 0.3 < │r│< 0.5 : Moderate correlation - 0.5 < │r│< 0.7 : Strong correlation - │r│> 0.7 : Very strong correlation CHAPTER 3 RESULTS 3.1. General features of the material of study From 7/2006 to 8/2008, 320 individuals pertaining to similar age range, and gender, and belonging to 2 groups: Patients’ group comprising 204 patients with tight MS, being PTMCed at VNHI and Control group with 116 healthy individuals. 3.1.1. Demographics of the Patients’ group (MS) Table 3.8. Demographics of the tight MS group Parameters Value ( X ± SD) or n (%) Age (years) 39.44 ± 10.79 (15 – 76) Gender F/M 165/39 Past history of commissurotomy (Surg/PTMC) 34 (16.7%) Stroke in the anamnesis 13 (6.3%) Rheumatic fever 31 (15.2%) Heart pulse (c/min) 91.79 ± 16.90 Sinus rhythm 120 (58.8%) Atrial fibrillation 84 (41.%) 3.1.1.1. Age range and gender 10 [...]... Changes of functional symptoms and Doppler echocardiography with time 3.5.1 Changes of functional symptoms (Table 3.32) Most cases improved their NYHA into level I, only 0.5% remain at NYHA IV 3.5.2 Changes of Doppler echocardiography parameters with time (Table 3.33) Table 3.33 Doppler echocardiography pre and post PTMC, with follow-up time Remarks : During consecutive months to PTMC, MVA, LALV maximal... Doppler is 3.29 ± 0.97 WU, while with catheterization, the value is 3.73 ± 1.02 WU, and there is no statistical meaning as p = 0.07 The correlation between the 2 methods is very strong (r = 0.92) (Fig 3.3) Similar results have been found with other authors 4.3 Doppler echocardiography results 4.3.1 Features of Doppler echocardiography in the MS group versus the control group It has been the first time... Ventricular Hypertrophy (RVH) 3.1.2.5 Some common Doppler echocardiography features Table 3.15 Doppler echocardiography in the MS group (n = 204) Parameters Value ( X ± SD) or n (%) Mean of Wilkins scoring 7.8 ± 0.88 (6 – 10) Wilkins ≤ 8 166 (81.4%) Wilkins > 8 38 (18.6%) Concomitant mild MR 155 (75.9%) Concomitant mild AR 36 ( 17.6%) 3.2 Head to head comparison of Doppler echocardiography versus catheterization... gender proportion control group, the following conclusions are given: 1 Pulmonary resistance (PVR) as assessed with Doppler echocardiography in MS cases is 3.23 ± 1.33 WU (Wood units), markedly elevated as compared to 1.52 ± 0.22 WU (p< 0.001) in the normal group • There is strong correlation between PVR with Doppler echocardiography or with catheterization (r = 0.92) • There is inverse linear correlation... parameters in cardiac Doppler ultrasound right after PTMC (24 hours, particularly PVR) 3.4.3.2 Changes in MR (Table 3.30) 13 Most patients showed increased MR as compared to pre PTMC, but their MR was within acceptable limits (mild or moderate) 3.4.3.3 Changes in TR Serious TR decreased notably right after PTMC, increasing thus cases with mild TR (p . by assessing the time integral velocity of blood flow at the RVOT (TVIrvot): Location: left side of sternum, short axis, using pulsed Doppler. • Assessment of PVR with cardiac Doppler ultrasound:. symptoms and Doppler echocardiography with time 3.5.1. Changes of functional symptoms (Table 3.32) Most cases improved their NYHA into level I, only 0.5% remain at NYHA IV 3.5.2. Changes of Doppler. Changes of Doppler echocardiography parameters with time (Table 3.33) Table 3.33. Doppler echocardiography pre and post PTMC, with follow-up time Remarks : During consecutive months to PTMC, MVA,