“The Heart Sound Quintet”: A Case Report of Right-Sided Heart Failure Due to Free Pulmonary Regurgitation Long After Intracardiac Repair of Tetralogy of Fallot

Background

Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease, accounting for 7–10% of all congenital heart diseases [1]. To date, intracardiac repair of TOF is generally performed during childhood. As a result, both structural and hemodynamic abnormalities are almost completely repaired. On the other hand, the majority of these patients will develop the sequelae long after the initial surgery, including pulmonary regurgitation (PR), right ventricular (RV) outflow tract obstruction, and pulmonary valvular stenosis, which results in significant RV dilation, RV myocardial dysfunction, and ultimately leads to right-sided heart failure [1]. Moreover, these post-operative sequelae are associated with significant morbidity and mortality for patients after intracardiac repair of TOF [2]. For these patients, high-technology imaging modalities, including cardiac computed tomography (CT), cardiac magnetic resonance imaging (MRI), and cardiac catheterization, are generally used for the assessment of structural and hemodynamic abnormalities. However, little is known regarding the utility of physical examination in the assessment of these sequelae.

Here, we present a case of repaired TOF with concomitant de-compensated right-sided heart failure due to severe PR, in which the structural abnormality and hemodynamic derangements were successfully assessed in detailed physical examinations.

Case Report

A 52-year-old man was admitted to a hospital because of sudden-onset palpitation and general fatigue. Electrocardiography revealed ventricular tachycardia with a heart rate of 180 beats/min. His heart rhythm returned to a sinus rhythm after prompt cardioversion and he was then referred to our institution for further investigation. His past medical history included RV outflow tract reconstruction using a homograft and closure of a ventricular septal defect for TOF, which was performed 47 years previously. However, he was lost to follow-up thereafter. Upon referral to our institution, his blood pressure was 116/70 mmHg, heart rate 80 beats/min, and oxygen saturation of 99% (on room air). On inspection of the jugular venous pulsation, a prominent a wave and deep y descent were clearly observed, which were consistent with the increased RV filling pressure and compensated augmentation of RA contraction. Of note, auscultation revealed a harsh diastolic regurgitant murmur in the third left intercostal space, widely split first heart sound (S1), and a single second heart sound (S2), indicating a severely dilated RV due to free PR and the presence of a non-functioning pulmonary valve. Moreover, a third heart sound (S3) was auscultated at the fourth parasternal border, which was consistent with a right-sided S3. The electrocardiogram revealed complete right bundle branch block, with a QRS duration of 200 ms. Chest radiography showed cardiomegaly with dilation of the bilateral pulmonary arteries (Figure 1). Transthoracic echocardiography revealed complete regression of the pulmonary valve, which resulted in free PR and a prominent RV dilation (Figure 2, Videos 1–3). Volumetric assessment of the RV was performed using cardiac MRI, which revealed an RV end-diastolic volume of 428 ml (RV end-diastolic volume index of 240 ml/m2), RV ejection fraction of 36%, and regurgitant fraction of PR of 74% (Figure 3, Video 4). Moreover, multi-detector row CT clearly showed complete regression of the pulmonary valve of the homograft (Figure 4).

The patient underwent catheter examination for further investigation of his hemodynamic state. His RA pressure waveform was particularly notable, consisting of a prominent a wave and deep y descent, which were coincident with the fourth heart sound (S4) and S3 on a phonocardiogram, respectively (Figure 5). Moreover, pulmonary arterial end-diastolic pressure and RV end-diastolic pressure were revealed to be almost identical due to the free PR. Thus the clinical assessment of the “heart sound quintet”, including a harsh diastolic regurgitant murmur, widely split S1, single S2, and the presence of right-sided S3 and S4, was confirmed using multimodal anatomical and hemodynamic evaluation as severe right-sided heart failure concomitant with a significantly dilated RV because of complete regression of the pulmonary valve and resultant free PR.

After pulmonary valve replacement, the “heart sound quintet” had completely resolved.

Discussion

Hemodynamic and structural abnormalities long after intracardiac repair of TOF can result in progressive electrical remodeling of the right side of the heart, and the mechano-electric interaction between QRS duration and RV dilation has been well demonstrated previously [3]. Moreover, it has been reported that RV myocardial stretch engenders areas of inhomogeneous electrical activity, predisposing to the development of life-threatening arrhythmia [3], as observed in our case.

S1 is composed of IM and IT components; thus, a widely split IM-IT interval indicates the delay of the IT component because of the presence of a significantly dilated RV due to hemodynamic load and could indicate a risk of life-threatening arrythmia. In this case, the RV end-diastolic volume index was revealed to be significantly dilated to 240 ml/m2 and the IM-IT interval was extremely prolonged at 150 ms as measured using a phonocardiogram. Thus, a widely split S1 can be used as a non-invasive marker of RV volume overload due to significant PR for patients after intracardiac repair of TOF.

In this case, the pulmonary valve of the homograft had almost completely disappeared due to aging degradation, resulting in free PR. Although S2 is normally composed of IIA and IIP, in this case IIP was not auscultated because of the absence of the pulmonary valve. Therefore, a harsh holo-diastolic murmur with a single S2 strongly suggested not only the presence of severe PR but also its pathogenesis.

S3 is known to be associated with elevated ventricular filling pressure, which is generally auscultated at the apex in patients with left-sided heart failure. However, right-sided S3 is indicated when S3 is heard at the left parasternal border and is enhanced during inspiration, as observed in our case. In fact, in this case, the RV end-diastolic pressure was elevated to 10 mmHg and a prominent y descent was observed in the RA waveform, which was quite compatible with the elevated filling pressure of the right side of the heart.

Finally, S4 is mainly created when the atrial contraction rapidly distends the ventricle in the presence of a non-compliant ventricle. Although the auscultation could not reveal the presence of S4, S4 was clearly exhibited on the phonocardiogram, coincident with a prominent a wave in the RA pressure waveform. When a massively dilated RV undergoes fibrotic remodeling and encounters space constraints due to the pericardium and thoracic cavity [4], a further increase in RV volume during atrial systole requires RA hypercontraction. Therefore, the presence of S4 is an important finding, indicating the presence of a non-compliant RV concomitant with elevated RV enddiastolic pressure.

Conclusions

We encountered a case of “heart sound quintet” that was composed of a widely split S1, single S2 with a harsh diastolic regurgitant murmur, and right-sided S3 and S4. Detailed physical examination contributed in the evaluation of not only structural but also hemodynamic derangements in a patient long after intracardiac repair of TOF. Life-long follow-up examinations in repaired TOF patients are important and will improve morbidity and mortality in this patient cohort.