Second heart sound in pulmonary hypertension

Noninvasive evaluation of pulmonary hypertension using the second heart sound parameters collected by a mobile cardiac acoustic monitoring system

Background

Pulmonary hypertension (PH) is linked to higher rates of morbidity and mortality worldwide. Early diagnosis of PH is important for clinical treatment. The estimated pulmonary artery systolic pressure (ePASP ≥ 35 mmHg) measured by echocardiography helps screen PH patients. In this paper, we report a novel PH screening method through a mobile cardiac acoustic monitoring system.

Methods

In the retrospective study, patients admitted to our hospital between January 2022 and April 2023 were classified into PH and control groups using ePASP and compared with acoustic cardiographic parameters. According to ePASP, PH severity was classified as mild, moderate, and severe. We analyzed the first and second heart sound (S1, S2) characteristics, including amplitude (S1A, S2A), energy (S1E, S2E), and frequency (S1F, S2F).

Results

The study included 209 subjects, divided into PH (n = 121) and control (n = 88) groups. Pearson correlation analysis confirmed the positive correlation between S2F and ePASP. The diagnostic performance of S2F as assessed by the area under the ROC curve was 0.775 for PH. The sensitivity and specificity of diagnosing ePASP ≥ 35 mmHg when S2F ≥ 36 Hz were found to be 79.34% and 67.05%, respectively, according to ROC analysis. Severity classification was performed using S2F, the area under the ROC curve was 0.712-0.838 for mild PH, 0.774-0.888 for moderate PH, and 0.826-0.940 for severe PH.

Conclusions

S2F collected by the mobile cardiac acoustic monitoring system offers a convenient method for remote PH screening, potentially improving PH management and outcomes.

Simulation of Acute Pulmonary Hypertension in Beagle Dogs

Acoustic cardiography (AC) combined with heart sound (HS) recording and electrocardiogram (ECG) provides a noninvasive and inexpensive way to understand the electrical mechanical activity of the heart. Pulmonary artery stenosis can cause hemodynamic abnormalities that might lead to pulmonary hypertension (PH). In this paper, we examined the relationships between the acoustic characteristics of the AC and hemodynamic changes in a beagle dog model of PH.Four healthy beagle dogs were injected with the prostaglandin endoperoxide receptor agonist U-44069 to induce acute PH states. AC was employed to analyze the process of pre-PH, intra-PH, and post-PH. Right ventricular blood pressure (RVBP) was measured via right cardiac catheterization, an invasive method performed in parallel for comparative hemodynamic evaluation. As RVBP increased or decreased, the HS features changed accordingly during acute PH occurrence and development. Right ventricular systolic blood pressure (RVSBP) significantly correlated with the minimum of the first HS (S1) amplitude (correlation coefficient (CC) = -0.82), energy of the S1 (CC = 0.86), energy of the second HS (S2) (CC = 0.67), entropy of the S1 (CC = -0.94), and ratio of electromechanical systolic time (EMST) to the cardiac cycle time (CC = 0.81). The two techniques (AC [HSs and ECG] versus right cardiac catheterization [RVBP]) were significantly correlated. Especially, the diastolic filling time (DFT) had a significant relationship with the right ventricular diastolic time (RVDT) (CC = 0.97), perfusion time (PT) (CC = 0.96), and cardiac cycle time (RR) (CC = 0.96). The CCs between the RVDT and the max dp/dt to min dp/dt, the EMST and the Q to min dp/dt, and the electromechanical activation time and the Q to max dp/dt were 0.95, 0.99, and 0.86, respectively. Furthermore, the logistic regression model with different combinations was used to identify the effective features for monitoring hemodynamic and pathophysiologic conditions.AC provided significant insight into mechanical dysfunction in a rapid and noninvasive way that could be used for early screening of PH.

Physical Examination for the Detection of Pulmonary Hypertension: A Systematic Review

We performed a systematic review to determine whether the physical examination can reliably assist in the diagnostic approach for patients suspected of having pulmonary hypertension (PH). Using dual extraction, two investigators independently searched PubMed, Ovid MEDLINE, Cochrane Library, and Embase for studies that compared physical examination findings with a right heart catheterization, from inception until July 10, 2021. We obtained data from four studies that evaluated physical examination findings in patients receiving a right heart catheterization to diagnose PH. Pooled diagnostic odds ratios (DOR) were calculated for right ventricular heave, a loud pulmonic component of the second heart sound (P2), jugular venous pressure (JVP) 3 cm above sternal angle, and a palpable P2. Three physical examination findings had DOR that supports the diagnosis of PH: the JVP > 3 cm above the sternal angle (5.90, 95% CI 2.57, 13.57), a loud P2 (2.91, 95% CI 1.38, 6.10), and a right ventricular heave (2.78, 95% CI 1.12, 6.89). The palpable P2 had a DOR less than one and was not able to be conclusive in diagnosing PH. Our systematic review found a small body of evidence supporting the use of physical examination tests in the diagnostic evaluation of pulmonary hypertension. The JVP > 3 cm above the sternal angle was the most accurate physical examination sign for the diagnosis of PH. Larger cohort studies using a combination of tests may shed more light on the role of the physical examination in the diagnosis and early detection of pulmonary hypertension.

A Prospective Evaluation of the Diagnostic Accuracy of the Physical Examination for Pulmonary Hypertension

BACKGROUND

The usefulness of physical examination findings for pulmonary hypertension (PH) is not well established. The purpose of this study was to evaluate prospectively the diagnostic performance of the physical examination for detecting PH.

METHODS

Consecutive patients undergoing right-sided heart catheterization (n = 116) were examined by an attending physician, medical resident, and medical student in a blinded fashion. Sensitivity, specificity, and positive and negative likelihood ratios (LRs) were calculated for each physical finding. Jugular venous pulsation (JVP) height was compared with right atrial pressure (RAP) by using linear regression. The association between physical findings and PH was assessed using univariate and multivariate logistic regression.

RESULTS

The prevalence of PH was 87%. Only a JVP > 3 cm (positive LR, 2.5; 95% CI, 1.2-5.4) and pulmonic regurgitation murmur (specificity, 100%; 95% CI, 79%-100%) helped rule in PH. The absence of JVP > 3 cm (negative LR, 0.4; 95% CI, 0.3-0.6) and absence of loud pulmonic component of the second heart sound (negative LR, 0.5; 95% CI, 0.3-0.9) had modest usefulness in excluding PH. JVP correlated with RAP (r = 0.59; P < .001) but tended to lead to underestimation of RAP (mean bias, -3.4 cm H₂O; 95% limits of agreement, -14.0 to 7.2). The presence of JVP > 3 cm and a parasternal heave discriminated PH (area under the curve [AUC] = 0.75). The combination of JVP > 3 cm, heave, and peripheral edema discriminated severe PH (mean pulmonary arterial pressure ≥ 45 mm Hg; AUC = 0.82).

CONCLUSIONS

Individual physical examination findings have inadequate diagnostic usefulness for PH. No combination of findings can be used to exclude PH, but the presence of high JVP, peripheral edema, and parasternal heave suggests severe PH.

Usefulness of the second heart sound for predicting pulmonary hypertension in patients with interstitial lung disease

CONTEXT AND OBJECTIVE

P2 hyperphonesis is considered to be a valuable finding in semiological diagnoses of pulmonary hypertension (PH). The aim here was to evaluate the accuracy of the pulmonary component of second heart sounds for predicting PH in patients with interstitial lung disease.

DESIGN AND SETTING

Cross-sectional study at the University of Brasilia and Hospital de Base do Distrito Federal.

METHODS

Heart sounds were acquired using an electronic stethoscope and were analyzed using phonocardiography. Clinical signs suggestive of PH, such as second heart sound (S2) in pulmonary area louder than in aortic area; P2 > A2 in pulmonary area and P2 present in mitral area, were compared with Doppler echocardiographic parameters suggestive of PH. Sensitivity (S), specificity (Sp) and positive (LR+) and negative (LR-) likelihood ratios were evaluated.

RESULTS

There was no significant correlation between S2 or P2 amplitude and PASP (pulmonary artery systolic pressure) (P = 0.185 and 0.115; P= 0.13 and 0.34, respectively). Higher S2 in pulmonary area than in aortic area, compared with all the criteria suggestive of PH, showed S = 60%, Sp= 22%; LR+ = 0.7; LR- = 1.7; while P2> A2 showed S= 57%, Sp = 39%; LR+ = 0.9; LR- = 1.1; and P2 in mitral area showed: S= 68%, Sp = 41%; LR+ = 1.1; LR- = 0.7. All these signals together showed: S= 50%, Sp = 56%.

CONCLUSIONS

The semiological signs indicative of PH presented low sensitivity and specificity levels for clinically diagnosing this comorbidity.

Utility of the physical examination in detecting pulmonary hypertension. A mixed methods study

INTRODUCTION

Patients with pulmonary hypertension (PH) often present with a variety of physical findings reflecting a volume or pressure overloaded right ventricle (RV). However, there is no consensus regarding the diagnostic utility of the physical examination in PH.

METHODS

We conducted a systematic review of publications that evaluated the clinical examination and diagnosis of PH using MEDLINE (1946-2013) and EMBASE (1947-2013). We also prospectively evaluated the diagnostic utility of the physical examination findings. Patients who underwent right cardiac catheterization for any reason were recruited. After informed consent, participants were examined by 6 physicians (3 "specialists" and 3 "generalists") who were unaware of the results of the patient's hemodynamics. Each examiner independently assessed patients for the presence of a RV lift, loud P2, jugular venous distension (JVD), tricuspid insufficiency murmur and right-sided 4th heart sound at rest and during a slow inspiration. A global rating (scale of 1-5) of the likelihood that the patient had pulmonary hypertension was provided by each examiner.

RESULTS

31 articles that assessed the physical examination in PH were included in the final analysis. There was heterogeneity amongst the studies and many did not include control data. The sign most associated with PH in the literature was a loud pulmonic component of the second heart sound (P2). In our prospective study physical examination was performed on 52 subjects (25 met criteria for PH; mPAP ≥ 25 mmHg). The physical sign with the highest likelihood ratio (LR) was a loud P2 on inspiration with a LR +ve 1.9, 95% CrI [1.2, 3.1] when data from all examiners was analyzed together. Results from the specialist examiners had higher diagnostic utility; a loud P2 on inspiration was associated with a positive LR of 3.2, 95% CrI [1.5, 6.2] and a right sided S4 on inspiration had a LR +ve 4.7, 95% CI [1.0, 15.6]. No aspect of the physical exam, could consistently rule out PH (negative LRs 0.7-1.3).

CONCLUSIONS

The presence of a loud P2 or audible right-sided 4th heart sound are associated with PH. However the physical examination is unreliable for determining the presence of PH.

Haemodynamic and structural correlates of the first and second heart sounds in pulmonary arterial hypertension: an acoustic cardiography cohort study

OBJECTIVE

To examine the relationship between acoustic characteristics of the first and second heart sounds (S1 and S2) and underlying cardiac structure and haemodynamics in patients with isolated pulmonary arterial hypertension (PAH) and controls.

DESIGN

Prospective multicentre cohort study.

SETTING

Tertiary referral and community hospitals.

PARTICIPANTS

We prospectively evaluated 40 PAH patients undergoing right-heart catheterisation with contemporaneous digital acoustic cardiography (intensity and complexity) and two-dimensional transthoracic echocardiography. To normalise for differences in body habitus, acoustic variables were also expressed as a ratio (S2/S1). 130 participants (55 also had haemodynamic and/or echocardiographic assessment) without clinical or haemodynamic evidence of PAH or congestive heart failure acted as controls.

RESULTS

Patients with PAH had higher mean pulmonary artery pressure (mPA; 40±13 vs 16±4 mm Hg, p<0.0001) and pulmonary vascular resistance (9±6 vs 1±1 Wood Units, p<0.0001) compared with controls, but cardiac index and mean pulmonary capillary wedge pressure were similar. More PAH patients had evidence of right ventricular (RV) dilation (50% vs 19%) and RV systolic dysfunction (41% vs 9%) in the moderate-severe range (all p<0.05). Compared with controls, the acoustic profiles of PAH patients were characterised by increased S2 complexity, S2/S1 complexity and S2/S1 intensity (all p<0.05). In the PAH cohort, S2 complexity was inversely related to S1 complexity. mPA was the only independent multivariate predictor of S2 complexity. The severity of RV enlargement and systolic impairment had reciprocal effects on the complexity of S2 (increased) and S1 (decreased). Decreased S1 complexity was also related to evidence of a small left ventricular cavity.

CONCLUSIONS

Acoustic characteristics of both S1 and S2 are related to the severity of PAH and are associated with RV enlargement and systolic dysfunction. The reciprocal relationship between S2 and S1 complexity may also reflect the underlying ventricular interaction associated with PAH.

Continuous-wave Doppler echocardiographic detection of pulmonary regurgitation and its application to noninvasive estimation of pulmonary artery pressure

Continuous-wave Doppler echocardiography was used to estimate pulmonary artery pressures by measuring pulmonary regurgitant flow velocity in 21 patients with pulmonary hypertension (mean pulmonary artery pressure greater than or equal to 20 mm Hg) and 24 patients without pulmonary hypertension. The pulmonary regurgitant flow velocity patterns, characterized by a rapid rise in flow velocity immediately after closure of the pulmonary valve and a gradual deceleration until the next pulmonary valve opening, were successfully obtained in 18 of the 21 patients with pulmonary hypertension and in 13 of the 24 patients without pulmonary hypertension. As pulmonary artery pressure increased, pulmonary regurgitant flow velocity became higher; the pulmonary artery-to-right ventricular pressure gradient in diastole (PG) was estimated from the pulmonary regurgitant flow velocity (V) by means of the simplified Bernoulli equation (PG = 4V2). The Doppler-determined pressure gradient at end-diastole correlated well with the catheter measurement of the pressure gradient at end-diastole (r = .94, SEE = 3 mm Hg) and with pulmonary artery end-diastolic pressure (r = .92, SEE = 4 mm Hg). The peak of Doppler-determined pressure gradient during diastole correlated well with mean pulmonary artery pressure (r = .92, SEE = 5 mm Hg). Thus continuous-wave Doppler echocardiography was useful for noninvasive estimation of pulmonary artery pressures.

Noninvasive evaluation of pulmonary hypertension by a pulsed Doppler technique

We used a pulsed Doppler technique to examine the flow velocity pattern in the right ventricular outflow tract in 33 adults. In the patients with normal pulmonary artery pressure (mean pressure less than 20 mm Hg, 16 patients), ejection flow reached a peak level at midsystole (137 +/- 24 msec, mean +/- SD), producing a domelike contour of the flow velocity pattern during systole. In contrast, the flow velocity pattern in patients with pulmonary hypertension (mean pressure greater than or equal to 20 mm Hg, 17 patients) was demonstrated to accelerate rapidly and to reach a peak level sooner (97 +/- 20 msec, p less than .01); in 10 of the pulmonary hypertensive patients a secondary slower rise in flow velocity was observed during a deceleration, resulting in the midsystolic notching. The time to peak flow (acceleration time, AcT) and right ventricular ejection time (RVET) were measured from the flow velocity pattern. Either AcT or AcT/RVET decreased with increase in mean pulmonary artery pressure, and a very high correlation (r = -.90) was found between AcT/RVET and log10 (mean pulmonary artery pressure). The use of this technique permitted the noninvasive estimation of the pulmonary artery pressure.

The cardiovascular effects of acute hypoxemia as a diagnostic aid

Acute hypoxemia produces opposite effects on the pulmonary and systemic vascular resistance. To assess the influence of acute hypoxemia on cardiac murmurs, 36 patients with a single valvular or congenital heart lesion were studied. As expected from these hemodynamic effects, right-sided regurgitant type murmurs increased in intensity during acute hypoxemia, while stenotic type murmurs were reduced. In contrast, left-sided murmurs remained constant or changed in opposite direction to their equivalent type from the right side. Additionally, acute hypoxemia produced a marked reduction of the murmurs due to left-to-right shunts and allowed an adequate differentiation of the murmurs due to ventricular septal defect from those due to mitral incompetence.

Abnormal pulmonic sound during acute massive pulmonary embolism

The findings in two patients with angiographically proven massive pulmonary embolism and with clinical and phonocardiographic evidence of abnormal respiratory movement of the pulmonic sound are reported. One patient with complete right bundle-branch block and another with normal conduction had a wide and fixed split second sound with a loud pulmonic component. Both patients had a moderate degree of pulmonary hypertension. Approximately two weeks after administration of heparin, the pulmonic sound moved normally during respiration in both patients. Thromboembolic pulmonary hypertension regressed in one patient and remained unchanged in the other. Changes in impedance through the large pulmonary arteries are are postulated to be responsible for the abnormal movement of the pulmonic valve during both phases of respiration. Wide expiratory splitting of the second sound should be an important clue in the diag nosis of acute massive pulmonary embolism, and the reappearance of a normal inspiratory splitting could be used at the beside to assess indirectly the rate of resolution of the blood clots.

Diagnosis of severe mitral regurgitation due to non-rheumatic chordal abnormalities

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Mitral stenosis with left-to-right shunt at atrial level. A diagnostic challenge

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