Pulmonary arterial V waves in mitral regurgitation: clinical and experimental observations

An Era of Digital Healthcare-A Comprehensive Review of Sensor Technologies and Telehealth Advancements in Chronic Heart Failure Management

Heart failure (HF) is a multi-faceted, complex clinical syndrome characterized by significant morbidity, high mortality rate, reduced quality of life, and rapidly increasing healthcare costs. A larger proportion of these costs comprise both ambulatory and emergency department visits, as well as hospital admissions. Despite the methods used by telehealth (TH) to improve self-care and quality of life, patient outcomes remain poor. HF management is associated with numerous challenges, such as conflicting evidence from clinical trials, heterogeneity of TH devices, variability in patient inclusion and exclusion criteria, and discrepancies between healthcare systems. A growing body of evidence suggests there is an unmet need for increased individualization of in-hospital management, continuous remote monitoring of patients pre and post-hospital admission, and continuation of treatment post-discharge in order to reduce re-hospitalizations and improve long-term outcomes. This review summarizes the current state-of-the-art for HF and associated novel technologies and advancements in the most frequently used types of TH (implantable sensors), categorizing devices in their preclinical and clinical stage, bench-to-bedside implementation challenges, and future perspectives on remote HF management to improve long-term outcomes of HF patients. The Review also highlights recent advancements in non-invasive remote monitoring technologies demonstrated by a few pilot observational prospective cohort studies.

A 3-Year Single Center Experience With Left Atrial Pressure Remote Monitoring: The Long and Winding Road

Background

Despite continuous advancement in the field, heart failure (HF) remains the leading cause of hospitalization among the elderly and the overall first cause of hospital readmission in developed countries. Implantable hemodynamic monitoring is being tested to anticipate the clinical exacerbation onset, potentially preventing an emergent acute decompensation. To date, only pulmonary artery pressure (PAP) sensor received the approval to be implanted in symptomatic heart failure patients with reduced ejection fraction. However, PAP's indirect estimation of left ventricular filling pressure can be inaccurate in some contexts.

Methods

The VECTOR-HF study (NCT03775161) is examining the safety, usability and performance of the V-LAP system, a latest-generation device capable of continuously monitoring left atrial pressure (LAP). In our center, five advanced HF patients have been enrolled. After confirmation of the transmitted data reliability, LAP trends and waveforms have guided therapy optimization. The aim of this work is to share clinical insights from our center preliminary experience with V-LAP application.

Results

Over a median follow-up time of 18 months, LAP–based therapy optimization managed to reduce intracardiac pressure over time and no hospital readmission occurred. This result was paralleled by an improvement in both functional capacity (6MWT distance 352.5 ± 86.2 meters at baseline to 441.2 ± 125.2 meters at last follow-up) and quality of life indicators (KCCQ overall score 63.82 ± 16.36 vs. 81.92 ± 9.63; clinical score 68.47 ± 19.48 vs. 83.70 ± 15.58).

Conclusion

Preliminary evidence from V-LAP application at our institution support a promising efficacy. However, further study is needed to confirm the technical reliability of the device and to exploit the clinical benefit of left-sided hemodynamic remote monitoring.

Cardiorenal Syndrome Triggered by Slowly Progressive Drugs Toxicity-Induced Renal Failure along with Minimal Mitral Disease: A Case Report

BACKGROUND

We report the case of a 93-year-old patient with normal left ventricular function and severe mitral annulus calcification, with mild mitral steno-insufficiency.

CASE PRESENTATION

She had developed creeping drugs-induced renal toxicity that is generally totally overlooked, due mainly to statins, a proton pump inhibitor, and aspirin. The Na and fluid retention, along with hypertension that ensued, although not severe, caused acute heart failure (sub-pulmonary edema) by worsening the mitral insufficiency. This occurred due to a less efficient calcific mitral annulus contraction during systole and an increasing mitral transvalvular gradient, as the transvalvular mitral gradient has an exponential relation to flow. After the suspension of the nephrotoxic drugs and starting intravenous furosemide, she rapidly improved. At 6 months follow-up, she is stable, in an NYHA 1-2 functional class, despite the only partial recovery of the renal function.

CONCLUSION

Progressive renal failure can functionally worsen even minimal mitral valvulopathy. Drug-induced nephrotoxicity can always be suspected in case of renal failure of unknown etiology. The suspension of the culprit drugs can improve renal function and dramatically improve the clinical symptoms even in a nonagenarian.

The V-LAP System for Remote Left Atrial Pressure Monitoring of Patients with Heart Failure: Remote Left Atrial Pressure Monitoring

OBJECTIVE

Patients with heart failure (HF) are at an increased risk of hospital admissions. The aim of this report is to describe the feasibility, safety and accuracy of a novel wireless left atrial pressure (LAP) monitoring system in HF patients.

METHODS

The V-LAP Left Atrium Monitoring systEm for Patients With Chronic sysTOlic & Diastolic Congestive heart Failure (VECTOR-HF) study is a prospective, multicenter, single-arm, open-label, first-in human clinical trial to assess the safety, performance and usability of the V-LAP system (Vectorious Medical Technologies, Ltd) in NYHA Class III HF patients. The device was implanted in the inter-atrial septum via a percutaneous, trans-septal approach, guided by fluoroscopy and echocardiography. Primary endpoints included the successful deployment of the implant, ability to perform initial pressure measurements and safety outcomes.

RESULTS

To date, 24 patients were implanted with the LAP monitoring device. No device-related complications have occurred. LAP was reported accurately, agreeing well with wedge pressure at 3 months (Lin's CCC=0.850). After 6 months, NYHA class improved in 40% of the patients (95% CI =16.4%-63.5%), while 6-minute walk test distance had not changed significantly (313.9 ± 144.9 vs. 232.5 ± 129.9 meters, p=0.076).

CONCLUSION

The V-LAP left atrium monitoring system appears to be safe and accurate.

Pulmonary Hypertension in Left Heart Disease

Pulmonary hypertension is common in left heart disease and is related most commonly to passive back transmission of elevated left atrial pressures. Some patients, however, may develop pulmonary vascular remodeling superimposed on their left-sided heart disease. This review provides a contemporary appraisal of existing criteria to diagnose a precapillary component to pulmonary hypertension in left heart disease as well as discusses etiologies, management issues, and future directions.

Fluid-structure interaction in a fully coupled three-dimensional mitral-atrium-pulmonary model

This paper aims to investigate detailed mechanical interactions between the pulmonary haemodynamics and left heart function in pathophysiological situations (e.g. atrial fibrillation and acute mitral regurgitation). This is achieved by developing a complex computational framework for a coupled pulmonary circulation, left atrium and mitral valve model. The left atrium and mitral valve are modelled with physiologically realistic three-dimensional geometries, fibre-reinforced hyperelastic materials and fluid–structure interaction, and the pulmonary vessels are modelled as one-dimensional network ended with structured trees, with specified vessel geometries and wall material properties. This new coupled model reveals some interesting results which could be of diagnostic values. For example, the wave propagation through the pulmonary vasculature can lead to different arrival times for the second systolic flow wave (S2 wave) among the pulmonary veins, forming vortex rings inside the left atrium. In the case of acute mitral regurgitation, the left atrium experiences an increased energy dissipation and pressure elevation. The pulmonary veins can experience increased wave intensities, reversal flow during systole and increased early-diastolic flow wave (D wave), which in turn causes an additional flow wave across the mitral valve (L wave), as well as a reversal flow at the left atrial appendage orifice. In the case of atrial fibrillation, we show that the loss of active contraction is associated with a slower flow inside the left atrial appendage and disappearances of the late-diastole atrial reversal wave (AR wave) and the first systolic wave (S1 wave) in pulmonary veins. The haemodynamic changes along the pulmonary vessel trees on different scales from microscopic vessels to the main pulmonary artery can all be captured in this model. The work promises a potential in quantifying disease progression and medical treatments of various pulmonary diseases such as the pulmonary hypertension due to a left heart dysfunction.

The Effects of Inhaled Sodium Nitrite on Pulmonary Vascular Impedance in Patients With Pulmonary Hypertension Associated with Heart Failure With Preserved Ejection Fraction

BACKGROUND

The severity of pulmonary hypertension (PH) is monitored by measuring pulmonary vascular resistance, which is a steady-state measurement and ignores the pulsatile load encountered by the right ventricle (RV). Pulmonary vascular impedance (PVZ) can depict both steady-state and pulsatile forces, and thus may better predict clinical outcomes. We sought to calculate PVZ in patients with PH associated with heart failure with preserved ejection fraction who were administered inhaled sodium nitrite to better understand the acute effects on afterload.

METHODS AND RESULTS

Fourteen patients with PH associated with heart failure with preserved ejection fraction underwent right heart catherization and were administered inhaled sodium nitrite. A Fourier transform was used to calculate PVZ for both before and after nitrite for comparison. Inhaled sodium nitrite decreased characteristic impedance (inversely related to proximal pulmonary artery compliance) and total work performed by the RV. RV efficiency improved, defined by a reduction in the total work divided by cardiac output. There was a mild decrease in pulmonary steady-state resistance after the administration of inhaled sodium nitrite, but this effect was not significant.

CONCLUSIONS

PVZ analysis showed administration of inhaled sodium nitrite was associated with an improvement in pulmonary vascular compliance via a decrease in characteristic impedance, more so than pulmonary steady-state resistance. This effect was associated with improved RV efficiency and total work.

Urgent mechanical circulatory support and transcatheter mitral valve repair for refractory hemodynamic compromise

Patients presenting with hemodynamic instability attributable to left ventricular systolic dysfunction and concomitant severe mitral regurgitation (MR) are increasingly recognized and pose complex management challenges. Surgical therapy is typically precluded owing to prohibitive mortality. The role of percutaneous mechanical circulatory support in such cases is well established; however, such interventions may be neither sufficient to achieve optimal stability nor prove definitive. The advent of novel catheter-based mitral repair modalities now offers primary decisive therapeutic intervention. Three cases of cardiogenic shock with severe MR illustrate the salutary hemodynamic and clinical responses to percutaneous mechanical support and valve repair by mitral clip.

Implantable Hemodynamic Monitoring for Heart Failure Patients

Rates of heart failure hospitalization remain unacceptably high. Such hospitalizations are associated with substantial patient, caregiver, and economic costs. Randomized controlled trials of noninvasive telemedical systems have failed to demonstrate reduced rates of hospitalization. The failure of these technologies may be due to the limitations of the signals measured. Intracardiac and pulmonary artery pressure-guided management has become a focus of hospitalization reduction in heart failure. Early studies using implantable hemodynamic monitors demonstrated the potential of pressure-based heart failure management, whereas subsequent studies confirmed the clinical utility of this approach. One large pivotal trial proved the safety and efficacy of pulmonary artery pressure-guided heart failure management, showing a marked reduction in heart failure hospitalizations in patients randomized to active pressure-guided management. "Next-generation" implantable hemodynamic monitors are in development, and novel approaches for the use of this data promise to expand the use of pressure-guided heart failure management.

Mitral regurgitation

Mitral regurgitation affects more than 2 million people in the USA. The main causes are classified as degenerative (with valve prolapse) and ischaemic (ie, due to consequences of coronary disease) in developed countries, or rheumatic (in developing countries). This disorder generally progresses insidiously, because the heart compensates for increasing regurgitant volume by left-atrial enlargement, causes left-ventricular overload and dysfunction, and yields poor outcome when it becomes severe. Doppler-echocardiographic methods can be used to quantify the severity of mitral regurgitation. Yearly mortality rates with medical treatment in patients aged 50 years or older are about 3% for moderate organic regurgitation and about 6% for severe organic regurgitation. Surgery is the only treatment proven to improve symptoms and prevent heart failure. Valve repair improves outcome compared with valve replacement and reduces mortality of patient with severe organic mitral regurgitation by about 70%. The best short-term and long-term results are obtained in asymptomatic patients operated on in advanced repair centres with low operative mortality (<1%) and high repair rates (>/=80-90%). These results emphasise the importance of early detection and assessment of mitral regurgitation.

Contrasting effect of similar effective regurgitant orifice area in mitral and tricuspid regurgitation: a quantitative Doppler echocardiographic study

We compared the effect of similar effective regurgitant orifice (ERO) areas in tricuspid regurgitation (TR) and mitral regurgitation (MR) on hemodynamics and volume overload, and examined the impact on grading of TR and MR severity. In a prospective study, 95 patients with TR in sinus rhythm were compared with 95 patients with MR in sinus rhythm matched for ERO area, age, and body surface area. We found that similar ERO area was associated with decreased volume overload in TR compared with MR. There were more women with TR than with MR, but comparison stratified by sex confirmed that regurgitant volume (RVol) was smaller in TR than in MR for similar ERO area. However, patients with systolic venous flow reversal (hepatic for TR and pulmonary for MR) had lower RVol but similar ERO area in TR compared with MR. Therefore, optimal diagnostic thresholds for severe regurgitation (maximum sum of sensitivity and specificity) in TR and MR were different for RVol (45 and 60 mL/beat, respectively) but similar for ERO area (40 mm(2)). We conclude that similar ERO areas induce less RVol in TR than in MR because of the decreased driving force in TR, but have similar consequences with regard to venous flow reversal. Therefore, a similar ERO area grading scheme can be used, and an ERO area of 40 mm(2) or greater is consistent with severe regurgitation in both TR and MR.

Myocardial bridging as a cause of acute transient left heart dysfunction

The significance of myocardial bridging is still a matter of debate, and although several reports have underlined its pathologic potential, myocardial bridging is often considered to be a benign phenomenon. We present here the case of a 63-year-old woman with a history of acute left heart failure and ECG evidence of ischemia, and whose primary abnormality on extensive workup was myocardial bridging. This case further underlines that myocardial bridging can lead to significant cardiac events.

Rapid estimation of regurgitant volume by the proximal isovelocity surface area method in mitral regurgitation: Can continuous-wave Doppler echocardiography be omitted?

The proximal isovelocity surface area (PISA) method is accurate for quantitating mitral regurgitation but requires recording both mitral maximal and integrated jet velocities using the same continuous-wave Doppler jet signal. In 272 consecutive patients with isolated mitral regurgitation, the mean ratio of maximal to integral of velocity had a narrow range of variation (mean +/- SD, 3.25 +/- 0.47). The estimated regurgitant volume, calculated as regurgitant flow/3.25, showed an excellent correlation with reference regurgitant volumes (r = 0.96 and r = 0.97; standard error of the estimate, 11 ml; both p < 0.0001), with limited overestimation and high sensitivity and specificity for severe mitral regurgitation. The estimated regurgitant volume is a useful measurement in patients in whom the continuous-wave Doppler signal of mitral regurgitation cannot be obtained.

Relationship between pulmonary capillary wedge V wave and transmitral and pulmonary venous flow velocity patterns in various heart diseases

BACKGROUND

A large V wave in a pulmonary capillary wedge pressure (PCWP) tracing is characteristic of mitral regurgitation. However, the V wave is often increased in patients without or with no significant mitral regurgitation.

METHODS AND RESULTS

The V wave was in the PCWP tracing investigated in 65 patients using transmitral flow (TMF) and pulmonary venous flow (PVF) velocity patterns obtained by transesophageal pulsed Doppler echocardiography. A large V wave was defined if the peak V wave minus the mean PCWP (V-mPCWP) was greater than 7 mmHg. Three study groups were formed: 15 patients with large V waves and significant mitral regurgitation, 15 patients with large V waves with no significant mitral regurgitation, and 35 patients with small V waves. The mPCWP and left ventricular end-diastolic pressure were greatest in the group with large V waves and no significant mitral regurgitation. Peak early diastolic TMF and PVF velocities were significantly greater in the two groups with large V waves. The peak second systolic PVF velocity was lowest in the group with large V waves and significant mitral regurgitation, followed by the group with large V waves and no significant mitral regurgitation. The V-mPCWP was positively correlated with the peak early diastolic TMF and PVF velocities and negatively correlated with the peak second systolic PVF velocities. Additionally, mitral regurgitation severity in patients with large V waves and significant mitral regurgitation was positively correlated with the peak early diastolic TMF and PVF velocities and negatively correlated with the peak second systolic PVF velocity.

CONCLUSIONS

These results suggest that large V waves in PCWP tracings appear not only in severe mitral regurgitation, but also in any condition with markedly elevated left ventricular end-diastolic pressure. Combined analysis of the TMF and PVF velocity patterns is helpful in determining the etiology of these hemodynamic abnormalities.

Value of systolic pulmonary venous flow reversal and color Doppler jet measurements assessed with transesophageal echocardiography in recognizing severe pure mitral regurgitation

We evaluated the value of color and pulsed Doppler transesophageal echocardiographic parameters and of V waves in estimating the severity of mitral regurgitation (MR) in 62 consecutive patients (38 men and 24 women, aged 39 to 80 years) with angiographically proven chronic pure MR (15 grade I/II, 47 grade III/IV). Twenty patients were examined before cardiac surgery under general anesthesia. Sensitivity, specificity, and positive and negative predictive values of systolic pulmonary venous flow reversal for the presence of grade III/IV MR were 87%, 93%, 98%, and 64%, respectively, these were for jet areas > or = 8.0 cm2--66%, 100%, 100%, and 48%, for jet lengths > or = 50 mm--70%, 87%, 94%, and 48%, for enlarged V waves--86%, 38%, 83%, and 43%, and for either flow reversal or a jet area > or = 8.0 cm2--96%, 93%, 98%, and 88%. We conclude that a combination of measurements improved the negative predictive value considerably, which is of importance in a population with a high pretest probability of severe MR. Enlarged V waves are not reliable in predicting severe MR. The optimal cutoff value for jet area and jet length was lower in anesthesized patients than in conscious patients; in anesthesized patients, sensitivity, specificity, and positive and negative predictive values of jet area > or = 5.0 CM2 for grade III/IV MR were 67%, 100%, 100%, and 50%, respectively; these were 87%, 100%, 100%, and 71% for flow reversal. Because the results of mitral repair are often evaluated with transesophageal echocardiography during surgery, our findings have clinical implications for evaluation of severe MR in anesthesized patients: pulmonary venous flow direction is the first-choice measure; jet area can be used when a low cutoff point is chosen.

Significance of diastolic pulmonary artery pressure peaks

We describe a patient undergoing elective surgery for treatment of an abdominal aortic aneurysm in whom an abrupt change in the contour of the pulmonary artery pressure (PAP) trace indicated the development of an intermediate (20 mm Hg) V wave in the pulmonary artery wedge pressure (PAWP) trace. As the PAP trace is displayed continuously, attention to its contour may allow for early detection of changes to the underlying PAWP trace.

Beyond the wedge: clinical physiology and the Swan-Ganz catheter

The Swan-Ganz catheter was introduced into general clinical medicine in 1970 and quickly gained widespread use in the management of critically ill patients. The device offers highly sophisticated physiologic information; however, in many instances, only the wedge pressure and the cardiac output are utilized when managing acutely ill patients. The purpose of this review is to illustrate and explain the array of physiologic data available from the Swan-Ganz catheter in most circumstances. A basic understanding of the information that can be obtained with the Swan-Ganz catheter is quite useful in the diagnosis and management of a variety of cardiovascular disorders. In addition, the Swan-Ganz catheter can be a helpful tool for teaching cardiovascular pathophysiology.