Balloon aortic valvuloplasty as a bridge to aortic valve replacement in a patient with severe calcific aortic stenosis

This case report describes a patient with severe calcific aortic stenosis who was initially considered inoperable because of a very poor left ventricular function and severe pulmonary hypertension. After balloon aortic valvuloplasty, the clinical and haemodynamic status of the patient improved to such an extent that subsequent aortic valve replacement was considered possible and eventually proved to be successful. Balloon aortic valvuloplasty has value as a potential bridge to aortic valve replacement when the risks for surgery are considered to be too high.     

Umbilical cord compression produces pulmonary hypertension in newborn lambs: a model to study the pathophysiology of persistent pulmonary hypertension in the newborn

We investigated the effects of chronic intrauterine hypoxaemia produced by prolonged partial umbilical cord compression on the circulation shortly after birth in lambs. Vascular catheters were inserted in 10 fetal sheep at 120 to 130 days gestation to measure descending aortic blood gases, arterial pH, and arterial O2 saturation. An inflatable silicone rubber balloon cuff was also placed around the umbilical cord. After recovery and the return of descending aortic blood gases to the normal range, the balloon was gradually inflated, decreasing the PaO2 from 21.2 +/- 3.6 to 17.5 +/- 1.3 mm Hg and the arterial O2 saturation from 57.1 +/- 9.2% to 37.2% +/- 5.2. After 14.3 +/- 3.7 days of partial umbilical cord compression, the lambs were delivered by Caesarean section, instrumented to measure systemic and pulmonary arterial, right atrial and pulmonary arterial wedge pressures, pulmonary and systemic blood flows, and mechanically ventilated. Five normal lambs were also studied. From 60 to 120 min after delivery, when compared to normal lambs, the umbilical compression lambs had an increased pulmonary arterial pressure (P less than 0.05) pulmonary vascular resistance (P less than 0.05), and right atrial pressure (P less than 0.05) with similar arterial blood gases. In both groups, hypoxic ventilation produced an increase in pulmonary arterial pressure (P less than 0.05) which on return to room air ventilation decreased to baseline in the normal lambs but not in the umbilical cord compression lambs (P less than 0.05). Prolonged partial umbilical cord compression produces chronic fetal hypoxaemia and pulmonary arterial hypertension after birth. This may represent a model to study the pathophysiology of persistent pulmonary hypertension syndrome.     

Modified heart-lung preparation for the evaluation of systolic and diastolic coronary flow in rats

A modified heart-lung preparation of the rat, which permits measuring systolic and diastolic coronary flow separately and enables coronary compliance to be evaluated, is described. The systemic circulation was substituted by a shunt circuit, and the elastic properties of the arterial tree were mimicked by a rubber balloon. Systolic and diastolic coronary flow was evaluated from the pulmonary and aortic flow signal. Integrated phasic pulmonary flow represented right ventricular stroke volume. Integrated phasic systolic aortic flow represented left ventricular stroke volume minus that volume flowing into the coronary arteries during systole, because the aortic flow probe had to be inserted distal to the origin of the coronary vessels. Because right and left ventricular stroke volume was identical under steady-state conditions, the difference between systolic pulmonary and systolic aortic flow resulted in systolic coronary flow. Diastolic coronary flow was measured by means of the retrograde flow through the aortic flow probe. Coronary compliance was calculated according to Frank's windkessel model from coronary resistance and from central diastolic aortic pressure, which decayed exponentially after switching out the rubber balloon and the shunt circuit. It could be shown that the proportion of systolic to diastolic coronary flow depends on coronary compliance.     

Pulmonary hypertension induced with an intra-arterial balloon: an alternate mechanism

The Laks catheter is a triple-lumen balloon catheter used to distend the canine main pulmonary artery while recording right ventricular pressure and the arterial pressure distal to the balloon. A rise in arterial pressure reported to occur during distension has been attributed to vasoconstriction rather than passive obstruction by the balloon. We tested this in six anesthetized dogs by inflating the Laks catheter-balloon while recording pressure distal to the balloon from the Laks catheter as well as from additional catheters in right and left pulmonary arteries placed retrogradely through lobar branches following thoracotomy. We found that balloon inflation increased pressures in the arterial port of the Laks catheter and in the left pulmonary artery catheter but reduced it in the right pulmonary artery. Tightening a snare around the right pulmonary artery had the same effects on pressures. Similar results were obtained while cardiac output was controlled by left ventricular bypass perfusion in four dogs. We conclude that the Laks catheter-balloon obstructs flow to the right lung and that the arterial pressure rise recorded in it during balloon inflation cannot be distinguished from that caused by occlusion of the right pulmonary artery.     

Effects of spinal anesthesia on response to main pulmonary arterial distension

Nonocclusive main pulmonary arterial distension produces peripheral pulmonary hypertension. The mechanism of this response is unknown. The effects of total spinal anesthesia on the response were studied in halothane-anesthetized dogs. Before total spinal anesthesia, main pulmonary arterial balloon inflation increased pulmonary arterial pressure and resistance without affecting systemic hemodynamic variables. Both right and left pulmonary arterial pressures were monitored to exclude unilateral obstruction with main pulmonary arterial balloon inflation. Total spinal anesthesia decreased cardiac output and systemic arterial pressures. After total spinal anesthesia, main pulmonary arterial distension still increased pulmonary arterial pressure and resistance. Right atrial pacing, discontinuation of halothane anesthesia, and norepinephrine infusion during total spinal anesthesia partially reversed the hemodynamic changes caused by total spinal anesthesia. The percent increase in pulmonary vascular resistance due to main pulmonary arterial distension was similar before total spinal anesthesia and during all experimental conditions during total spinal anesthesia. The pulmonary hypertensive response is therefore not dependent on central synaptic connections.     

The Role of Rubella in the Etiology of Supravalvular Aortic Stenosis

The possibility of an etiological relationship between rubella embryopathy and sporadic forms of supravalvular aortic stenosis is considered. A case is presented of a patient with rubella embryopathy and supravalvular aortic stenosis associated with pulmonary valvular and peripheral pulmonary artery stenosis, bicuspid aortic valve, aortic valve stenosis and subendothelial myocardial fibrosis. A review of the literature revealed many clinical and pathological features common to both syndromes. The hypothesis that rubella virus produced germ-cell mutation and subsequent persistence of rubella in the zygote produced further fetal damage is presented to explain these observations.     

Bedside evaluation of the resistance of large and medium pulmonary veins in various lung diseases.

To evaluate the contribution of large and medium pulmonary veins to the total pulmonary vascular resistance in various human lung diseases, we compared in 64 patients the pulmonary arterial proximal wedge pressure (Ppw), obtained when the balloon of a 7F pulmonary artery catheter was inflated with 1.5 ml air, with the distal wedge pressure (Pdw), obtained after the tip of the catheter was advanced until wedged in a small artery without balloon inflation. Ppw, reflecting the pressure in a large pulmonary vein, approximates the left atrial pressure, whereas Pdw reflects the pressure in a smaller pulmonary vein. Pdw was greater than Ppw in all 64 patients. The Pdw-Ppw gradient was 1.1 +/- 0.5 mmHg in nine patients with normal lungs and was significantly higher in 13 patients with chronic congestive heart failure (3.8 +/- 0.8 mmHg, P less than 0.01) and in 22 patients with adult respiratory distress syndrome (3.8 +/- 0.8 mmHg; P less than 0.01), but not in 20 patients with chronic obstructive pulmonary disease (1.8 +/- 0.7 mmHg). The distribution of the pulmonary vascular resistance was clearly different among the four groups. The fraction of the total pulmonary vascular resistance attributable to large and medium pulmonary veins was significantly increased (P less than 0.01) in adult respiratory distress syndrome (27.5 +/- 12%) and cardiac patients (27.5 +/- 9%) compared with patients with chronic obstructive pulmonary disease (13 +/- 5%) and normal lungs (13.5 +/- 6%).(ABSTRACT TRUNCATED AT 250 WORDS)     

Successful percutaneous balloon valvuloplasty in a preterm infant weighing 1500 g with critical pulmonary valve stenosis

We describe a successful cardiac intervention in an infant, born at 32 weeks of gestation, with a birth weight of 1040 g, who had a critical pulmonary valve stenosis with the right ventricular pressure twice the systemic pressure. Continuous prostaglandin E infusion kept the arterial duct open and at the age of four weeks and a weight of 1500 g a balloon valvuloplasty was performed, which reduced the systolic right ventricular pressure to below the systemic pressure. Two weeks later the procedure was repeated because of increasing right ventricular pressure. At two months of age the mean systolic transpulmonary Doppler gradient was 30 mmHg with an adequate right ventricular volume. The neurological status of the infant was normal and the femoral vein was patent. Timely interventional heart catheterisation is a successful method of treatment in critical pulmonary valve stenosis in infants with a low birth weight. (Neth Heart J 2008;16:264-6.)     

Balloon dilatation of the aortic valve for inoperable aortic stenosis.

The place of balloon dilatation of the aortic valve in the treatment of calcific aortic stenosis is controversial. Thirty two patients (mean age 76) in whom valve replacement was contraindicated were followed up for three to 24 months (mean 8); 25 were in functional class III or IV according to the New York Heart Association''s classification. Major complications of the procedure occurred in four patients. Echocardiography and Doppler studies were performed before operation and before discharge in 28 patients, and the area of the valve was measured again six to 50 (mean 23) weeks after operation in 11 patients. The peak to peak aortic pressure gradient fell from a mean of 65 (SD 24) to 46 (20) mm Hg, but the area of the aortic valve, measured by Doppler echocardiography, in 18 patients showed a modest but significant increase, from 0.61 (0.16) to 0.74 (0.23) cm2. One month after dilatation, 29 patients were alive, of whom 17 had improved symptoms. Only two had lasting clinical benefit. Sixteen patients died, 12 of a cardiac cause. The estimated one year survival rate was 49%. Six patients underwent or required valve replacement because of persisting symptoms. In view of its limited long term efficacy balloon dilatation of the aortic valve should be used only for patients with severe symptoms whose life expectancy is limited by other disease or who are considered to be unsuitable for valve replacement. It may have a role in improving the condition of patients who present with cardiogenic shock or pulmonary oedema before valve replacement is undertaken.     

New Concept in Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA)

The world-wide impact of traumatic injury and associated hemorrhage on human health and well-being is significant. Methods to manage bleeding from sites within the torso, referred to as non-compressible torso hemorrhage (NCTH), remain largely limited to the use of conventional operative techniques. The overall mortality rate of patients with NCTH is approximately 50%. Studies from the wars in Afghanistan and Iraq have suggested that up to 80% of potentially survivable patients die as a result of uncontrolled exsanguinating hemorrhage. The commercially available resuscitative endovascular balloon occlusion of the aorta (REBOA) is a percutaneous device for the rapid control of torso hemorrhage in trauma. A compliant balloon is inserted via the femoral artery and inflated in the thoracic or abdominal aorta, providing inflow control of the abdomen, pelvis, or groin/lower extremities. Recent studies indicate that REBOA carries an inherent risk of aortic injury due to over-inflation and possible risk of aortic or iliac artery rupture. A new approach isto resolve the issue of balloon sizing and over-inflation. We propose a novel concept to be used in trauma facility for arterial occlusion to eliminate arterial injury and the risk of vascular rupture through real time balloon diameter profile measurements to ensure proper inflation. The proposed concept, called Smart Resuscitative Endovascular Balloon Occlusion (SREBO) will be novel in the following aspects: 1) It will have electrical conductance-based navigation technology to target the desired site of balloon deployment in the aorta, 2) The balloon can determine the time of proper inflation using electrical conductance catheter technology. This technology would eliminate the risk of arterial rupture and simplify the procedure in the trauma facility or medical clinics without significant training. The results can be displayed on a handheld device. This novel device has the potential to save civilians in trauma or soldiers injured on the battlefield.     

The evolution of the treatment of isolated pulmonary valve stenosis

In the course of studies covering 40 years, 1913 to 1953, leading to the development of cardiopulmonary bypass, many ingenious blind instrumental or digital intrusions were made into the heart chambers to treat lesions therein. Limits were defined for the arrest of circulation through part or all of the heart to permit a brief glimpse of the lesion and effect at least a partial correction. The often remarkably good results of operations performed under less than ideal operating conditions for lesions such as isolated pulmonary stenosis encouraged the interventional cardiologist and radiologist, working together, to adapt the cardiac catheter, used previously for exploration of the vascular system and diagnosing intravascular lesions, to therapeutic purposes. They positioned a catheter with uninflated balloon attached in the pulmonary artery, then either by inflating the balloon beyond the constricted orifice and pulling it through or by rapidly and precisely inflating the balloon lying across the orifice were able to disrupt the stricture and relieve the stenosis. Results matched those of early non-visual operations. Recently the cardiologist has expanded the approach to relieve other constricted orifices in the heart and great vessels and to close abnormal openings. In isolated pulmonary stenosis, the nearly complete relief of obstruction and the tolerance of the circulation to blunt disruption of valvular stenosis bodies well for the long-term success of balloon valvuloplasty in this congenital malformation of the heart.     

良性中心气道狭窄支气管镜介入治疗术后近远期再狭窄相关因素分析

目的探讨良性中心气道狭窄支气管镜介入治疗术后近远期再狭窄相关因素。方法对2011年2月~2015年2月我院收治的60例良性中心气道狭窄患者经支气管镜下介入治疗,治疗方式包括高频电刀、冷冻、球囊扩张、金属覆膜支架置入等。治疗后对患者的治疗时机、局部感染情况、治疗方法、气道狭窄病因、年龄、性别、基础疾病等情况进行分析,随访观察评估术后疗效、出现再狭窄的时间,探讨近远期再狭窄的危险因素。结果 Cox回归分析表明,患有基础疾病(高血压、糖尿病)、球囊扩张、支架置入、治疗时机不当(溃疡坏死增值阶段)、局部感染是良性气管狭窄支气管镜下腔内介入治疗术后近期再狭窄的相关危险因素,其对再狭窄影响的风险比(OR值)依次为6.715、2.197、5.820、6.914、5.345。支架置入和治疗时机不当(溃疡坏死增值阶段)是良性气管狭窄支气管镜下腔内介入治疗术后远期再狭窄的相关危险因素,其对再狭窄影响的风险比(OR值)分别为6.706,7.154。结论良性中心气道狭窄患者支气管镜下腔内介入治疗术后近期再狭窄的危险因素是基础疾病、球囊扩张、支架置入、局部感染、治疗时机不当,远期再狭窄危险因素是支架置入和治疗时机不当。     

A ventricular-vascular coupling model in presence of aortic stenosis

In patients with aortic stenosis, the left ventricular afterload is determined by the degree of valvular obstruction and the systemic arterial system. We developed an explicit mathematical model formulated with a limited number of independent parameters that describes the interaction among the left ventricle, an aortic stenosis, and the arterial system. This ventricular-valvular-vascular (V(3)) model consists of the combination of the time-varying elastance model for the left ventricle, the instantaneous transvalvular pressure-flow relationship for the aortic valve, and the three-element windkessel representation of the vascular system. The objective of this study was to validate the V(3) model by using pressure-volume loop data obtained in six patients with severe aortic stenosis before and after aortic valve replacement. There was very good agreement between the estimated and the measured left ventricular and aortic pressure waveforms. The total relative error between estimated and measured pressures was on average (standard deviation) 7.5% (SD 2.3) and the equation of the corresponding regression line was y = 0.99x - 2.36 with a coefficient of determination r(2) = 0.98. There was also very good agreement between estimated and measured stroke volumes (y = 1.03x + 2.2, r(2) = 0.96, SEE = 2.8 ml). Hence, this mathematical V(3) model can be used to describe the hemodynamic interaction among the left ventricle, the aortic valve, and the systemic arterial system.     

INSERTION OF AN INTRAAORTIC BALLOON THROUGH A LIMB OF AN AORTOFEMORAL GRAFT AFTER AORTIC VALVE REPLACEMENT, DOUBLE CORONARY ARTERY BYPASS, AND RESECTION OF AN ABDOMINAL AORTIC ANEURYSM

This case report describes a useful and unusual route for insertion of an intraaortic balloon in 63-year-old man who was operated upon for calcific aortic stenosis, coronary atherosclerosis involving the left anterior descending and right coronary arteries, and a large abdominal aortic aneurysm. Aortic valve replacement was accomplished with a porcine heterograft prosthesis. Bypasses to the left anterior descending and right coronary arteries were constructed with reversed saphenous vein grafts, and the abdominal aneurysm was resected and repaired with a bifurcated woven Dacron vascular graft. An electively placed intraaortic balloon was inserted through the right limb of the aortic graft prosthesis and used to assist the patient during the immediate postoperative period. Uneventful recovery ensued.     

Pulmonary arterial distension does not cause pulmonary vasoconstriction

Distension of the main pulmonary artery or its major branches with an intraluminal balloon has been reported to cause pulmonary vasoconstriction by an unknown mechanism. This study was an attempt to confirm the pressor response and explore its cause. Several balloon distension methods were tried and discarded because they caused unintentional obstruction. Ultimately, I inflated a balloon placed retrogradely and confined to the left main pulmonary artery of six anesthetized open-chest dogs after ligating left lobar arterial branches. Blood flow and systemic gas composition were controlled by interposing an external pump oxygenator between the left ventricle and aorta. Pressures in the aorta, main pulmonary artery, and left atrium were recorded. Alveolar hypoxia was used as an independent test of pulmonary vasoreactivity. Although hypoxic pressor responses occurred, challenges with arterial distension did not change lung perfusion pressure. Silicone rubber casts were made of the arteries of six dogs used in pilot experiments. These revealed the limited lengths in which distenders can be placed without unintentional encroachment on flow. I could not support the conclusion that arterial distension causes vasoconstriction and am suspicious that the perfusion pressure increases reported by others may have been caused by undetected obstruction of a major arterial branch.     

Effect of thoracic duct drainage on hydrostatic pulmonary edema and pleural effusion in sheep

Positive end-expiratory pressure (PEEP) increases central venous pressure, which in turn impedes return of systemic and pulmonary lymph, thereby favoring formation of pulmonary edema with increased microvascular pressure. In these experiments we examined the effect of thoracic duct drainage on pulmonary edema and hydrothorax associated with PEEP and increased left atrial pressure in unanesthetized sheep. The sheep were connected via a tracheostomy to a ventilator that supplied 20 Torr PEEP. By inflation of a previously inserted intracardiac balloon, left atrial pressure was increased to 35 mmHg for 3 h. Pulmonary arterial, systemic arterial, and central venous pressure as well as thoracic duct lymph flow rate were continuously monitored, and the findings were compared with those in sheep without thoracic duct cannulation (controls). At the end of the experiment we determined the severity of pulmonary edema and the volume of pleural effusion. With PEEP and left atrial balloon insufflation, central venous and pulmonary arterial pressure were increased approximately threefold (P less than 0.05). In sheep with a thoracic duct fistula, pulmonary edema was less (extra-vascular fluid-to-blood-free dry weight ratio 4.8 +/- 1.0 vs. 6.1 +/- 1.0; P less than 0.05), and the volume of pleural effusion was reduced (2.0 +/- 2.9 vs. 11.3 +/- 9.6 ml; P less than 0.05). Our data signify that, in the presence of increased pulmonary microvascular pressure and PEEP, thoracic duct drainage reduces pulmonary edema and hydrothorax.     

A mechanical device for aortic compliance modulation: in vitro simulation of aortic dissection treatment

Stanford type A aortic dissection often rapidly leads to death from aortic rupture. We considered the possibility of introducing a passive counterpulsating damper into the dissected aorta in order to limit the physical stress associated with ventricular ejection and increase the diastolic aorto-ventricular pressure gradient. We conceived a damping device comprising an intravascular balloon connected to an adjustable external reservoir to regulate the air pressure inside the balloon, and performed a simulation study using a mechanical model of the cardiovascular system, mimicking aortic dissection. When the balloon was completely deflated, the behavior of the aortic pressure signal was typical of low-compliance aortic dissection, as characterized by an augmented maximum systolic value, accentuated diastolic decay, and a very low end-diastolic value. Balloon inflation (at incremental steps to 90 mmHg) progressively restored the aorto-ventricular pressure gradient and reduced peak systolic pressure values, leading to progressive improvements in the characteristics of the aortic pressure curve in terms of reduction in the maximum systolic value and slower diastolic decay. The proposed mechanism might exert beneficial effects at two levels: (1) directly, by reducing mechanical stress on the arterial wall; (2) indirectly, by allowing safer use of pharmaceutical agents (beta-blockers etc.). In vivo animal simulation studies are warranted to verify the effects of the device and optimize balloon shape and volume in a realistic pathophysiological setting.     

YC-1, a benzyl indazole derivative, stimulates vascular cGMP and inhibits neointima formation

The pathobiologic process of arterial stenosis following balloon angioplasty continues to be an enigmatic problem in clinical settings. This research project investigates the ability of YC-1, a benzyl indazole derivative that sensitizes sGC/cGMP, to stimulate endogenous cGMP and attenuate balloon injury-induced neointima (NI) formation in the rat carotid artery. Northern and Western blot analyses revealed enhanced acute expression of iNOS and inducible heme oxygenase (HO-1) mRNA and protein in the injured artery. The contralateral uninjured artery also demonstrated acute HO-1 mRNA and protein induction without detectable iNOS expression. Perivascular application of YC-1 immediately following injury significantly stimulated acute vessel wall cGMP compared to untreated controls. YC-1 treated sections demonstrated significant reduction in NI area (-74%), NI area/medial wall area (-72%), and NI thickness (-76%) 2 weeks post-injury. These results directly implicate YC-1 as a potent new therapeutic agent capable of reducing post-angioplasty stenosis through endogenous CO- and/or NO-mediated, cGMP-dependent processes.     

经隐动脉建立糖尿病兔股动脉血管狭窄模型

目的探讨建立糖尿病兔股动脉损伤后血管狭窄的模型方法。方法采用四氧嘧啶静脉注射建立糖尿病兔模型。建模成功后分为手术组、对照组,手术组接受了经隐动脉途径行球囊损伤股动脉术,对照组不行球囊损伤。术后均给予普食喂养,4周处死,行HE染色后观察血管狭窄情况。结果所有兔均完成了手术,24只存活至实验结束,平均手术时间（26±7）min,成功造成糖尿病兔股动脉狭窄模型,平均相关狭窄达（88.11±1.9）%。结论成功建立了糖尿病兔股动脉损伤后狭窄的实验模型,手术成功率高,操作时间少,存活率高,模型稳定,重复性好,为糖尿病外周血管病变的实验研究提供了借鉴方法。