Respiratory mechanics and gas exchange in an ovine model of congenital heart disease with increased pulmonary blood flow and pressure

In a model of congenital heart disease (CHD), we evaluated if chronically increased pulmonary blood flow and pressure were associated with altered respiratory mechanics and gas exchange. Respiratory mechanics and gas exchange were evaluated in 6 shunt, 7 SHAM, and 7 control age-matched lambs. Lambs were anesthetized and mechanically ventilated for 15 min with tidal volume of 10 mL/kg, positive end-expiratory pressure of 5 cmH2O, and inspired oxygen fraction of 0.21. Respiratory system, lung and chest wall compliances (Crs, CL and Ccw, respectively) and resistances (Rrs, RL and Rcw, respectively), and the profile of the elastic pressure-volume curve (%E2) were evaluated. Arterial blood gases and volumetric capnography variables were collected. Comparisons between groups were performed by one-way ANOVA followed by Tukey-Kramer test for normally distributed data and with Kruskal-Wallis test followed by Steel-Dwass test for non-normally distributed data. Average Crs and CL in shunt lambs were 30% and 58% lower than in control, and 56% and 68% lower than in SHAM lambs, respectively. Ccw was 52% and 47% higher and Rcw was 53% and 40% lower in shunt lambs compared to controls and SHAMs, respectively. No difference in %E2 was identified between groups. No difference in respiratory mechanics was observed between control and SHAM lambs. In shunt lambs, Rcw, Crs and CL were decreased and Ccw was increased when compared to control and SHAM lambs. Pulmonary gas exchange did not seem to be impaired in shunt lambs when compared to controls and SHAMs.

Efficacy and safety of propranolol in infants with heart failure due to moderate-to-large ventricular septal defect (VSD-PHF study) - A prospective randomized trial

AIMS

The utility of beta-blocker therapy in infants with heart failure (HF) due to significant left-to-right shunt lesions is not known. The study aimed to assess the efficacy and safety of propranolol in infants with HF due to moderate-to-large ventricular septal defect (VSD).

METHODS

The prospective randomized trial included 80 infants with HF and moderate-to-large VSD, randomly allocated to receive either conventional therapy alone (n = 40) or propranolol plus conventional therapy (n = 40). The primary endpoint was a composite of all-cause mortality, hospitalization for HF and/or chest infection, and referral for surgery. The secondary clinical outcomes were the individual components of the composite endpoint. In addition, the patients were followed up to detect safety outcomes, for example, bronchospasm, bradyarrhythmia, and worsening HF symptoms.

RESULTS

The addition of propranolol therapy to the conventional medications did not result in significant improvement in the primary composite endpoint (32.50% vs. 52.50%; P = 0.07). There was a trend toward improvement, but the study is underpowered for this important question. However, propranolol therapy significantly decreased the risk of hospitalization (12.50% vs. 32.50%; P = 0.03) and worsening of Ross HF class (5.41% vs. 28.21%; P = 0.01) as compared to conventional therapy (estimated number needed to treat = 5). Propranolol did not result in any significant safety concerns in these infants except bronchospasm in an infant.

CONCLUSIONS

Propranolol therapy in infants with significant left-to-right shunt may prevent worsening in HF symptoms and hospitalization and is well tolerated. However, it does not reduce mortality or need for surgery.

Transcatheter occlusion of an anomalous origin of left coronary artery from pulmonary artery in an adult as an alternative to surgery

Anomalous origin of the left coronary artery from the pulmonary artery causes heart failure and death in infancy. In rare adult survivors with well-developed collaterals, surgical left coronary ligation to arrest steal is often combined with bypass grafting. Transcatheter left coronary artery closure in a symptomatic adult as an alternative to surgical ligation resulted in complete resolution of inducible ischaemia on myocardial perfusion imaging.

Isolated systemic arterial supply to normal lung - an unusual cause of extracardiac left-to-right shunt

Isolated systemic arterial supply to a normal lung, a type of bronchopulmonary vascular malformation, is a rare cause of extracardiac left-to-right shunt. We describe such a case that was successfully managed by transcatheter closure of the anomalous arterial supply to otherwise normal lung.

Haemodynamics of an iatrogenic atrial septal defect after MitraClip implantation

BACKGROUND

The MitraClip procedure requires transseptal access of the left atrium with a 24F guiding sheath. We evaluated invasively whether a MitraClip induced iatrogenic atrial septal defect (IASD) leads to development of a relevant interatrial shunt and right ventricular overload.

METHODS

A total of 69 patients who underwent a MitraClip procedure due to a severe mitral valve regurgitation (MVR) were included in the observational, retrospective cohort study. All pressures were directly measured throughout the procedure. Cardiac index (CI), systemic (Qs) and pulmonary (Qp) flow were calculated using the Fick method.

RESULTS

Successful MitraClip implantation increased CI (2.5 ± 0.62 vs 3.05 ± 0.77 L/min/m² ; P < .0001), whereas SVR (1491 ± 474 vs 997 ± 301 dyn s/cm⁵ ; P < .0001), PVR (226 ± 121 vs 188 ± 96 dyn/s/cm⁵ ; P = .04), PCWP (23 ± 6.1 vs 20 ± 4.7 mm Hg; P = .0031), PA pressure (33.6 ± 7.2 vs 31.9 ± 6.6 mm Hg; P = .1437) and LA pressure (21.5 ± 5.4 vs 18.7 ± 4.9 mm Hg; P < .0001) all decreased. The effect on LA pressure was further enhanced by guiding catheter retrieval (14.4 ± 4.6 mm Hg; P < .0001). At the end of the procedure, Qp (6.033 ± 1.3 L/min) exceeded Qs (5.537 ± 1.3 L/min) by 0.496 L/min leading to a Qp:Qs ratio of 1.09 (P = .007). After 6 months, echocardiography revealed no changes in RV diameter (42.96 ± 6.95 mm vs 43.81 ± 7.67 mm; P = .62) and TAPSE (17.13 ± 3.33 mm vs 17.36 ± 3.24 mm; P = .48).

CONCLUSION

Our data show that the MitraClip procedure does not induce a relevant interatrial shunt or right ventricular overload. In fact, future studies will have to show whether the IASD may even be beneficial in selected patient populations by left atrial volume and pressure relief.

Uneventful Follow-Up 2 Years after Endovascular Treatment of a High-Flow Iatrogenic Aortocaval Fistula Causing Pulmonary Hypertension and Right Heart Failure

Iatrogenic aortocaval fistula is an extremely rare pathologic condition that often results in clinically significant left-to-right extracardiac shunt. In slow-progressing cases, chronic right-sided heart failure can occur and, in some patients, may persist for years. We present a patient with a long-standing aortocaval fistula that was causing high-flow left-to-right shunting, tricuspid regurgitation, severe pulmonary hypertension, and right-side heart failure. After undergoing complete endoscopic isolation of the aortocaval fistula, the patient experienced dramatic clinical improvement and continued to have excellent imaging and clinical resolution after 2 years of follow-up.

Atrial septal defects and pulmonary arterial hypertension

Atrial septal defects (ASD) are a common congenital heart defect. The majority of patient with ASDs often follow an uncomplicated course of events. However, a proportion of patients with ASDs, may have their condition complicated by pulmonary hypertension (PH), with a subsequent significant impact on management, morbidity and mortality. The presence of PH, influences the suitability for defect closure. In this review we describe the different types of ASDs, the classification of PH related to congenital heart disease (CHD), when ASD closure is contraindicated and the management of patients who develop pulmonary arterial hypertension (PAH), including the most extreme form, Eisenmenger syndrome (ES).

Atrial Septal Defects Accelerate Pulmonary Hypertension Diagnoses in Premature Infants

Between 4 and 16% of extremely premature infants have late pulmonary hypertension (PH) (onset >30 days of life), and infants with PH have a higher risk of tracheostomy and death. Atrial septal defects (ASD) increase pulmonary blood flow and may promote PH in at-risk infants. The objective of this study was to determine if infants with ASD develop PH sooner than those without ASD. Infants who were born at < 32 weeks' gestation, with an echocardiogram on day of life > 30, and without congenital anomalies were included. Infants with and without ASD were evaluated for the time to PH diagnosis, defined as the day of the first echocardiogram that showed PH. A multivariable model with ASD and significant variables on PH and a Cox proportional hazard model evaluating time to PH was determined. Of the 334 infants with echocardiograms, 57 had an ASD and 26% of these developed PH vs. 12% without ASD (p = 0.006). Infants with PH had lower gestational age (25.2 vs. 26.2 weeks, p = 0.005), smaller birthweight (699 vs. 816 gm, p = 0.001), and more prematurity complications than infants without PH. More PH infants had maternal African-American race (63.9 vs. 36.1%), right ventricular dysfunction (23.9 vs. 3.2%, p < 0.001), right ventricular dilation (52.1 vs. 8.6%, p < 0.001), or right ventricular hypertrophy (51.2 vs. 10.1%, p < 0.001), than infants without PH. At 150 days of life, 78.1% (95% CI 64.6-86.9%) of infants with ASD survived without PH, compared with 90.9% (95% CI 86.7-93.8%) of infants without ASD, and the unadjusted hazard for development of PH for infants with ASD was 2.37 (95% CI 1.29-4.36). When significant clinical variables were controlled, infants with ASD had a 2.44-fold (95% CI 1.27-4.68) increase in PH, compared with infants without ASD. Most PH in infants with or without ASD was diagnosed by day of life 150, but infants with ASD had an over 2-fold increased hazard for PH during their neonatal hospitalization. Premature infants with ASD should be followed closely for PH development and further studies to investigate the optimal timing of closure are needed.

Age is not a good predictor of irreversibility of pulmonary hypertension in congenital cardiac malformations with left-to-right shunt

OBJECTIVE

Congenital cardiac malformations with high pulmonary blood flow and pressure due to left-to-right shunts are usually repaired in early infancy for both the benefits of early relief of heart failure and the fear that the concomitant pulmonary hypertension may become irreversible unless these defects are corrected at an early age. Age, however, has been a poor predictor of irreversibility of pulmonary hypertension in our experience, which is presented here.

DESIGN

A retrospective observational study. We defined "late" as age ≥2 years. We examined clinical, echocardiographic, and hemodynamic data from all patients aged ≥2 years with such malformations referred to us from 2004 untill 2015.

SETTING

Department of Pediatric Cardiology and Cardiac Surgery, University Hospital of Vaud, Lausanne, Switzerland.

PATIENTS

There were 39 patients, aged 2-35 years (median: 5 years), without chromosomal abnormalities. All had malformations amenable to biventricular repair, and all had high systolic right ventricular pressures by echocardiography prior to referral.

INTERVENTIONS

All patients underwent catheterization for assessment of pulmonary hypertension. If this was reversible, surgical correction was offered.

OUTCOME MEASURES

(1) Operability based on reversibility of pulmonary hypertension. (2) When surgery was offered, mortality and evidence of persisting postoperative pulmonary hypertension were examined.

RESULTS

Eighteen patients had no pulmonary hypertension, 5 of variable ages were inoperable due to irreversible pulmonary hypertension, and 16 had reversible pulmonary hypertension. Therefore, 34 patients underwent corrective surgery, with no immediate or late mortality. Pulmonary arterial and right ventricular pressures decreased noticeably in all operated patients. This is sustained to date; they are all asymptomatic with no echocardiographic evidence of pulmonary hypertension at a median follow-up of 7 years (range 2-13 years).

CONCLUSIONS

Pulmonary hypertension may still be reversible in many surprisingly old patients with left-to-right shunt lesions, who may therefore still be operable.

Congenital heart diseases and anaesthesia

Patients with congenital heart diseases (CHDs) are at increased risk of developing complications during anaesthesia. Improvements in medical and surgical management in recent decades have resulted in significantly more children with CHD surviving to adulthood. The aim of this article is to focus on broad classification of CHD and to provide an updated review on the current perioperative anaesthetic management of CHD patients in different settings such as (a) interventional cardiac procedures that have dominated the field, (b) uncorrected patients for non-cardiac surgery and (c) corrected patients for non-cardiac surgery. The complexity of the defects along with a variety of non-cardiac surgery makes it impossible to have one single-anaesthesia technique. Search on Ovid, PubMed, Google Scholar and Medline were done with MeSH terms such as 'congenital heart disease', 'cardiac catheterisation', 'anaesthetic management' and 'non-cardiac surgery' mainly focusing on review articles and controlled studies for preparing the article.

Postcorrective surgery improvement of nocturnal hypoxemia in a case of partial anomalous pulmonary venous connection and aberrant hepatic vein drainage

Partial anomalous pulmonary venous connection (PAPVC) is a rare congenital anomaly that leads to an anatomical left-to-right shunt. Termination of the intrahepatic inferior vena cava (IVC) with its azygos continuation associated with the hepatic venous connection to the left atrium (LA) is also a rare congenital anomaly that results in an anatomical right-to-left shunt. A 65-year-old male presented with severe dyspnea on exertion and pedal edema. He was further diagnosed at our clinic and was found to have both the aforementioned congenital abnormalities, creating a bidirectional shunt. On further investigation, he was found to have nocturnal hypoxemia on overnight oximetry. The patient was successfully treated via surgical corrections of the congenital anomalies leading to symptomatic improvement as well as the resolution of nocturnal hypoxemia.

Relationship between pulmonary arterial resistance and compliance among patients with pulmonary arterial hypertension and congenital heart disease

BACKGROUND

It is unknown whether changes in pulmonary arterial resistance (Rp), pulmonary arterial compliance (Cp), and the product of Rp and Cp (the RC time) in patients with pulmonary arterial hypertension (PAH) are related to an increase in pulmonary blood flow. The aim of this study is to clarify relationships between these parameters before and after corrective surgery among patients with PAH and congenital heart disease.

METHODS

We performed cardiac catheter examinations and compared Rp, Cp, and the RC time before and after corrective surgery in 100 infants (53 boys) with PAH related to ventricular septal defect.

RESULTS

Median age at surgery was 2.9 (0.6-28.5) months. Preoperative values of the ratio of pulmonary to systemic blood flow (Qp/Qs), systolic pulmonary arterial pressure (PAP), Rp, Cp, and the RC time were 3.5 (2.7-4.3), 65 (56-70) mm Hg, 2.18 (1.64-3.19) Wood unit/m(2), 2.67 (2.01-3.38) mL/mm Hg/m(2), and 0.36 (0.31-0.40) seconds, respectively. Postoperative systolic PAP, Cp, and the RC time were significantly decreased to 26 (23-29) mm Hg, 1.96 (1.77-2.26) mL/mm Hg/m(2), and 0.31 (0.26-0.36) seconds, respectively, although Rp remained unchanged at 2.53 (2.06-3.31) Wood unit/m(2). The relationship between Rp and Cp was inversely related before and after surgery, and the Rp-Cp coupling curve was shifted downward after surgery. In addition, lower preoperative Cp (partial regression coefficient = -3.35; P = .001) and preterm delivery (partial regression coefficient = 6.28; P = .02) were independently related to postoperative higher systolic PAP.

CONCLUSIONS

Rp-Cp coupling depends on both the amount of pulmonary blood flow and the condition of the pulmonary vasculature. Lower preoperative Cp is an independent predictive factor to predict higher postoperative pulmonary systolic pressure leading to an increase in right ventricular workload. It is necessary to assess Rp-Cp coupling before surgery among patients with PAH related to congenital heart disease.

Coronary sinus to left atrium communication

Coronary sinus anomalies are rare. They can be associated with other vascular anomalies such as persistent left superior vena cava or can occur in isolation. We present a rare case of an isolated coronary sinus communication to the left atrium. This anomaly may be clinically relevant in the setting of significant left-to-right shunting or when shunt reversal results from right-sided heart failure. It may also be significant in cases of persistent atrial fibrillation after attempted pulmonary vein isolation.