Case presentation

A 61-year-old woman with severe aortic stenosis was referred for aortic balloon valvuloplasty. She has a complex past medical history including a renal transplant 7 years ago with a baseline creatinine of 2.0 mg/dL, prior coronary bypass graft surgery 10 years earlier, peripheral vascular disease, diabetes, hypertension, ongoing tobacco abuse with chronic obstructive pulmonary disease, and known aortic stenosis. She presented with increasing dyspnea and two- to three-pillow orthopnea punctuated by an episode of paroxysmal nocturnal dyspnea. On examination, her blood pressure was 110/64 with a heart rate of 119 beats/minute. She was in marked respiratory distress with prominent rales, a murmur of severe aortic stenosis, and elevated jugular venous pressure. Her laboratory values were notable for a rise in creatinine from her baseline of 2.0 mg/dL to 3.4 mg/dL. An echocardiogram confirmed severe aortic stenosis with a peak instantaneous gradient of more than 100 mmHg and reduced left ventricular function with an estimated ejection fraction of 35% to 40%. She was placed on 100% non-rebreather face mask, which resulted in adequate oxygenation, and was sent urgently to the cardiac catheterization laboratory.

Cardiac catheterization

Cardiac catheterization consisted only of a hemodynamic study in order to avoid worsening renal function from exposure to iodinated contrast agents. Her baseline hemodynamics revealed severe heart failure with a mean right atrial pressure of 11 mmHg, a pulmonary artery pressure of 53/27 mmHg and a mean pulmonary capillary wedge pressure of 33 mmHg. The cardiac output was 4.8 L/minute. Using a straight wire to cross the aortic valve, the operator placed a dual-lumen pigtail catheter into the left ventricle and measured a baseline peak-to-peak systolic gradient across the aortic valve of 94 mmHg, yielding a calculated valve area of 0.7 cm² (Figure 49-1). An extra-stiff, 0.038 inch Amplatz guidewire was advanced through the pigtail catheter into the left ventricle and the pigtail catheter removed. The originally inserted 6 French arterial sheath was replaced with a 12 French sheath, and a 5 cm long by 18 mm diameter valvuloplasty balloon was advanced and centered across the aortic valve. Using a 30-cc syringe filled with dilute contrast, the balloon was inflated by hand (Figure 49-2 and Video 49-1). The balloon was deflated and removed over the guidewire and replaced with the dual lumen pigtail catheter. The operator noted that the transaortic peak-to-peak systolic pressure gradient only diminished by 20 mmHg. Thus, a 5 cm long by 22 mm diameter balloon was advanced, centered across the aortic valve, and inflated. The transaortic pressure gradient after the second balloon inflation is shown in Figure 49-3, with the peak-to-peak systolic gradient noted to fall to 44 mmHg, yielding a valve area of 1.1 cm².

FIGURE 49-1 These waveforms represent simultaneous left ventricular and central aortic pressure and demonstrate a peak-to-peak systolic pressure gradient of 94 mmHg. Note also the marked elevation of left ventricular end diastolic pressure at 40 mmHg.

FIGURE 49-2 Balloon valvuloplasty was performed with a 20 mm diameter by 5 cm balloon.

FIGURE 49-3 The pressure waveforms were collected after balloon valvuloplasty. The pressure gradient had decreased to 44 mmHg and left ventricular end diastolic pressure had dropped to 20 mmHg.

Postprocedural course

Following the valvuloplasty, she felt symptomatically improved with less respiratory distress and was rapidly weaned to 4 liters of oxygen by nasal cannula. Her renal function returned to baseline over the subsequent days after the procedure. With the improvement in her clinical status and the understanding that a valvuloplasty represented a temporary solution to her aortic stenosis, attention was turned to her potential surgical candidacy. Six days after the valvuloplasty, with her creatinine at baseline, she underwent coronary angiography that demonstrated total occlusion of the circumflex and right coronary arteries and severe stenosis of the proximal left anterior descending artery, with patent vein grafts to the right coronary and circumflex arteries but an occluded left subclavian artery supplying the left internal mammary to the left anterior descending artery. Heavy calcification of the aorta was also noted. Clinically improved, she decided to wait until after the holidays to consider surgery on her aortic valve and was discharged 9 days after the valvuloplasty; however, she was readmitted the next day with severe dypnea and found to be in congestive heart failure with acute renal failure. This time, she required mechanical ventilation and an intraaortic balloon pump was inserted to improve her heart failure. An echocardiogram showed reduced left ventricular function and a peak instantaneous gradient of 80 mmHg. Unfortunately, she was not able to be weaned from the ventilator and dialysis was initiated because of continued deterioration in renal function. Consultation with cardiothoracic surgery was obtained. A reoperation consisting of an aortic valve replacement with correction of the subclavian occlusion supplying the left internal mammary artery in a patient in Class IV heart failure with serious comorbid conditions including excessive aortic calcification and advanced lung and kidney disease was deemed to be of unacceptable risk. After extensive discussions with the patient and her family, her level of care was changed to comfort measures and she expired several days later.

Discussion

Aortic balloon valvuloplasty is an effective method to treat congenital aortic stenosis, but its efficacy in calcific aortic stenosis is limited. Original reports from the 1980s confirmed its role primarily as a palliative procedure. In one series of 170 patients with severe aortic stenosis undergoing balloon valvuloplasty, the peak transaortic gradient fell from about 70 mmHg to 36 mmHg with the valve area increasing from an average of 0.6 to 0.9 cm².¹ Thus, patients are still left with significant aortic stenosis and, although symptoms typically improve, the restenosis rate is very high, with at least 50% of patients experiencing restenosis within 6 to 12 months. Importantly, aortic balloon valvuloplasty does not improve long-term survival, which remains very poor and not different from the expected survival for untreated severe aortic stenosis.^2,3 For these reasons, aortic balloon valvuloplasty is recommended as a Class IIb indication only as a bridge to aortic valve surgery in hemodynamically unstable patients (i.e., severe heart failure or shock) with severe aortic stenosis at high risk for emergency aortic valve surgery or as a palliative procedure in a patient with severe symptomatic aortic stenosis who is not an operative candidate.⁴ The procedure was chosen for the patient presented in this case because she was felt to be unsuitable for an emergent heart operation due to progressive renal failure and refractory pulmonary edema. The goal of the procedure was to improve her hemodynamic status such that her renal failure and heart failure would improve to a point that valve replacement surgery could proceed at a much lower risk. The procedure resulted in the usual and expected degree of hemodynamic improvement and initially, clearly improved her clinical status. Unfortunately, her comorbid illnesses, particularly her renal failure, exacerbated her condition, precluding her candidacy for aortic valve surgery and she succumbed to the disease.

The usual procedural technique is described in this case. The retrograde approach is fairly simple, but requires up to a 12 French sheath; this may be an issue in patients with peripheral vascular disease. An alternative is to position the balloon anterograde across the aortic valve via a transseptal puncture, using an Inoue balloon.⁵ This approach requires a great deal of skill but can reduce the risk of vascular complication. When the retrograde approach is used, it may prove difficult to position the balloon during inflations because of the tendency to “spit” or “watermelon seed.” Brief bursts of rapid ventricular pacing at ventricular rates of 180 to 200 beats per minute can be employed to transiently lower the cardiac output and allow the balloon to inflate without movement.

In the current era, balloon valvuloplasty is being commonly used as an adjunct to percutaneous aortic valve replacement, facilitating passage and positioning of the prosthesis. The safety, efficacy, and role of percutaneous aortic valves are currently under study. Initial reports are promising. Had it been available, this might have been an effective therapy in the patient presented here.